LANTHANIDE CHELATES of FLUORINATED A-Oiketones

Home , Metal acetylacetonates

LANTHANIDE CHELATES OF FLUORINATED a-oIKETONES

A thesis submitted to the

Faculty of Science

in candidacy for the degree of

Master of Science

Andrew McPherson Hamer,

BSc (Melb. J

Supervisor: Professor Stanley E. Livingstone

School of Chemistry,

The University of New South Wales ~.arch 1984 To my parents

It is hereby declared that this thesis has not been submitted, in part or in full, to any other University or Institution for any degree whatsoever.

(Andrew M. Hamer) TABLE OF CONTENTS

Page No.

ABSTRACT V

ACK..~OWLEDGEMENTS vi

INTRODUCTION 1

PART ONE

PREPARATION OF THE LANTHANIDE CHELATES

I. Preparation of Fluorinated B-Diketone Ligands 4

II. Preparation and Analyses of Lanthanide Chelates 7

III. Determination of Associated Waters 8

IV. Experimental 15

PART TWO

CRYSTAL STRUCTURE OF DIAQUOTRIS(4,4,4-TRIFLUORO

l-(3'-METHYLPHENYL)-l,3-BUTANEDIONATO)ERBIUM(III) HYDRATE

I. Background •.• 18

II. Experimental 21

III. Results and Discussion 25

IV. Programs Used 35

PART THREE

VISIBLE SPECTRA OF THE

LANTHANIDE CHELATES

I. Background ... 37

II. Results and Discussion 39

III. Experimental 69

,... , , PART FOUR

MAGNETIC PROPERTIES OF THE

LANTHANIDE CHELATES Page No.

I. Background 70

II. Results and Discussion 72

III. Experimental ••• 95

PART FIVE

MASS SPECTRA OF THE LANTHANIDE CHELATES

I. Background 105

II. Results and Discussion 110

III. Experimental ••. 136

APPENDIX A. Detailed Magnetic Data .•• 137

APPENDIX B. Detailed Mass Spectra 143

APPENDIX C. Atomic Positions and Thermal Parameters of Crystal Structure .. 160

PUBLICATIONS .•• 162

GLOSSARY. Conventions of Mass Spectrometric Notation 163

ABBREVIATIONS 164

REFERENCES 165

iv ABSTRACT

Seventy lanthanide complexes of S-diketones have been prepared under carefully controlled conditions. They have been characterised by carbon, hydrogen, and metal analyses.

The crystal structure of diaquotris(4,4,4-trifluoro-l-(3'-methyl phenyl)-1,3-butanedionato)erbium(III) hydrate was determined.

Visible spectra were obtained for most complexes exhibiting

-1 absorptions in the range 13000 to 30000 cm The main features observed were:

1. The visible spectra change minimally with chelation.

2. Hypersensitive absorptions were found for complexes of

neodymium, holmium and erbium.

The variation of the magnetic properties of selected complexes with

temperature was observed. All except samarium and europium gave a Curie-

Weiss dependence, and all conformed with previous experimental results

for lanthanide compounds.

Mass spectra were obtained for all the complexes. The most

interesting features were:

1. All the lanthanide chelates gave essentially similar mass spectra.

2. Fluorine migration to the metal occurred with all the lanthanide

complexes.

3. Valency change from 3 to 2 occurred with samarium (4£5), europium

(4£6), thulium (4£12) and ytterbium (4£13).

4. Valency change from 3 to 4 occurred with cerium (4f1), but not

with terbium (4£8).

V ACKNOWLEDGEMENTS

The author gratefully acknowledges the assistance of the following people:

Professor S.E. Livingstone, for the opportunity to undertake the degree, his guidance, understanding, and supervision in preparing this tbesis.

Mr. A.T. Baker, for much assistance in the solution and refinement of the crystal structure, his discussion on all areas of the thesis, and his support in the laboratory.

Mr. D.C. Craig for the collection of the X-ray diffraction data.

Dr. J.J. Brophy for persisting with the numerous mass spectra that he obtained.

Dr. H.P. Pham, for the many microanalyses.

Miss N.J. Ferguson, Mr. M. Antolovich, and all other members of the inorganic research laboratory for making the time enjoyable as well as rewarding.

Mrs. G. Ferris and Mrs. N. Ravey for typing this thesis.

vi INTRODUCTION

With the first complexes being prepared in 1887, complexes of

S-diketones are amongst the most widely studied coordination compounds.

The capacity of the S-diketones to form inner coordination compounds with a large variety of metals has provided inorganic chemists with what were

rare examples of electro-positive metal ions in combinations displaying

characteristics of covalent compounds, i.e., solubility in organic

solvents and volatility. These characteristics have been exploited in

solvent extraction and gas-liquid chromatographic techniques. Metal

complexes of B-diketones are also used as contact shift reagents for

better resolution of nuclear magnetic resonance spectra of a variety of

complex organic molecules, in laser technology and in the polymer

industry.

S-Diketones, of which a large variety may be synthesised by Claisen

condensation, are capable of keto-enol tautomerism. The hydrogen atom

of the CH2 group is activated by the adjacent C=O groups and a conjugated system can arise by prototropic shift. The proportion of the enol

tautomers generally increases when there is an electron withdrawing group

such as an aromatic ring or fluorinated substituent is present in the

ligand. 60 •72 The enolic hydrogen atom of the ligand can be replaced by

a metal cation to produce a six membered chelate ring.

The lanthanides (or rare earths) are the fourteen elements that

follow lanthanum in the periodic table and in which fourteen 4f electrons

are added successively to the electronic configuration of lanthanum.

The 4£ electrons are relatively uninvolved in bonding, so the whole

series has a remarkably similar chemistry, for which the Sd16s2

1 2

outer electronic configuration of lanthanum is the prototype.

All the lanthanides are highly electropositive and readily form tervalent ions. Although the tervalent state is always the most stable, certain ions are known to display variable valency. Cerium (4f1) and terbium (4f8) are known to exist as quadrivalentions, and samarium (4f5), 6 13 europium (4f) and ytterbium (4f ) form the bivalent ion. The reason for the existence of thesequadrivalentand bivalent states has been ascribed to the approach of formation of empty, half-full or full 4f orbitals.

The shielding of one 4f electron by another is imperfect owing to the shapes of the f orbitals. For each successive lanthanide the effective nuclear charge experienced by each 4f electron increases, causing a reduction in size of the entire 4f shell. The accumulation of each successive contraction is the total lanthanide contraction. As a result tervalent lanthanum has a radius of 1.061 Acompared to 0.848 A for tervalent lutetium. 84 Yttrium has a similar outer shell electronic configuration and has many properties very similar to those of the lanthanides, especially erbium. This is because tervalent yttrium has a radius of 0.893 A compared to 0.881 A for tervalent erbium. For this reason yttrium, though not strictly a lanthanide, has been included in

the scope of this work.

The lanthanides exist in the natural state together, thus due to

the similarity of their chemistry, separation of the lanthanides has been

of some difficulty. The ions that show variable valency may be separated

easily, but the remainder require special techniques.

The most stable and common complexes of the lanthanides are those

with chelating oxygen ligands. Water-soluble complexes of EDTA have

been used in ion exchange separations. Due to the volatility of 3

complexes of S-diketones containing large organic groups or fluorine, various attempts have been made to separate the lanthanides by gas 28 81 chromatography. ' The volatility of these complexes is utilised in

this work to obtain the mass spectra of the complexes.

The coordination number either of a given lanthanide ion or for a

series of lanthanide ions of the same charge appears to be determined

more by spatial accommodation of the ligands than by the bonding charac

teristics of the ligands.66 The coordination number in solution commonly

differs from the coordination number in a crystal,given the same ligand

and same lanthanide ion. The water molecule has a strong affinity for

the lanthanide ion, and thus effectively competes for coordination sites.

The coordination numbers of the complexes are rarely six,and higher

coordination numbers (with coordinated waters) appear to be the rule.

One of the first investigators of lanthanide complexes of

S-diketones was Urbain (1886 to 1889). He prepared the hydrated

tris(acetylacetonates) of lanthanum, yttrium and gadolinium. Interest

in complexes of the lanthanides was greatly increased in the 1940's with

the need to separate fission products. PART ONE

PREPARATION OF THE LANTHANIDE CHELATES

I. Preparation of Fluorinated 8-Diketone Ligands

The preparation of the fluorinated 8-diketones was conducted as 35 described by Ho and Livingstone. The method is an example of a crossed Claisen condensation where a hydrogen ion is abstracted from the appropri ate 1 y sub stitute. d acetop h enone b y means o f met h oxi"d e ions.. 58,60

The abstraction is selective for hydrogens adjacent to the carbonyl group. The resultant powerfully nucleophilic carbanion attacks the carbonyl carbon of ethyl trifluoroacetate to displace an ethoxide ion, yielding the desired fluorinated 8-diketone. The hydrogen ion abstraction may be carried out in the presence of the ethyltrifluoro acetate as it contains no hydrogens adjacent to the carbonyl group. The mechanism for the reaction is given in Figure 1.1.

Purification of the fluorinated 8-diketone was done by complexation with copper(!!) ions. The 8-diketone was regenerated by hydrogen sulfide gas.

The colour, melting point, and analytical data for the four fluorinated 8-diketones prepared are given in Table 1.1. Also included is 4,4,4-trifluoro-l-(2'-thienyl)-1,3-butanedione (obtained from Aldrich

Chemicals) and l,l,l-trifluoro-5,5-dimethyl-2,4-hexanedione (obtained from

PCR Research Chemicals). 22 In 1974 Das reported the preparation of several of the fluorinated

8-diketones used in this work. He prepared 4,4,4-trifluoro-l-(3'-methyl-

phenyl)-1,3-butanedione, 4,4,4-trifluoro-1-(2'-methylphenyl)-l,3-butane- 5

R /CH CF3 R /CH2 /CF3 'c "c ~/I "'cII II ~<-~-- II 0 /0 0 0 \ /H

of B-diketone formation. Figure 1.1. Mechanism 6

Table 1.1

Analytical Data for Fluorinated 6-Diketones RC(O)CH 2C(O)CF 3

R Yield Colour m.p.* or b.p. Found (Cale.) (%) at 760 mm Hg %C %H (literature)

42* 43.2 2.3 cream (lit.60 43) (43.3) (2. 3)

57* 40.6 2.4 40 yellow (lit. 25 56) ( 40. 7) (2.1) m-BrC6H4 35 yellow 36* 40.9 2.3 (lit.25 39) ( 40. 7) (2.1)

246 57.4 4.1 yellow m-CHf6H4 45 (lit.22 244) (57 .4) (3.9)

250 57.6 4.2 o-CHf6H4 55 orange (lit.22 255) (57 .4) (3.9)

b 142 49.1 5.9 C(CH3) 3 colourless (lit.60 140) ( 49. 0) (5. 7)

a Aldrich Chemicals b PCR research chemicals. 7

dione and 4,4,4-trifluoro-1-(4'-bromophenyl)-l,3-butanedione, all of which were new. No lanthanide complexes of these ligands have been made before.

II. Preparation and Analyses of the Lanthanide Chelates

The preparations of the lanthanide chelates of the various fluorin ated S-diketones were conducted in a similar manner to that described by

Livingstone and Zimmermann,56 which in turn was a modification of the method used by Stites et ai. 82 in the preparation of the trisacetylaceton- ates of the lanthanides. The method gave a reasonably high yield of

60-85%; an alternative method used by Melby et ai.62 for diaquotris

(4,4,4-trifluoro-l-(2'-thienyl)-1,3-butanedionato)europium(III) had a reported yield of only 15%.

The fluorinated S-diketones coordinate to the lanthanide ions by loss of a proton from either of their enol forms, to form water-insoluble tris-chelates.

Experimentally, the deprotonation was carried out by the addition of an equimolar amount of dilute ammonia. The deprotonated fluorinated

S-diketone was edded slowly to an excess of the appropriate lanthanide salt (usually the nitrate) dissolved in aqueous ethanol. During t:he addition the pH was maintained in the range 6.0-6.5 to prevent reproton ation of the ligand or precipitation of the lanthanide hydroxide. The complex was precipitated by the addition of watPr.

Purification of lanthanide chelates was achieved by recrystallisation 81 33,19 from dichloromethane or water/alcohol. For the g~owth of crystals

~ dichloromethane was superior, but recrystallisations were only done

when the analyses were unsatisfactory because the yield of purified

comµound was low (approximately 30%). 8

Attempts to prepare complexes of 4,4,4-trifluoro-l-(3'-oromotihenyl) l,3-butanedione did not yield the pure products, a trace of a nitrogen impurity being present in the microanalyses even after several recrystallisations. Presumably complete coordination with the lanthanide ions did not occur, so traces of the ammonium salt of the ligand remained.

The preparation of the ortho-bromo substituted ligand 4,4,4-trifluoro-

1-(2'-bromophenyl)-1,3-butanedione was attempted; however, upon purification by chelation with copper(II) ions, no product was obtained.

The bulky bromine in the ortho position on the phenyl ring either sterically hinders the coordination to the copper(II) ions, or prevents the initial formation of the ligand.

Despite the inability to synthesise the ortho-bromo substituted ligand no difficulty was found in preparing complexes of the ortho-methyl substituted ligand 4,4,4-trifluoro-1-(2'-methylphenyl)-1,3-butanedione, although the methyl group occupies nearly the same volume as a bromine atom.

In all, five fluorinated B-diketones were chelated to the fourteen

lanthanides available, yielding a total of seventy complexes. The

analytical data of the complexes are listed in Tables 1.2 to 1.6.

Several of the chelates of 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedione

and 1,1,l-trifluoro-5,5-dimethyl~2,4-hexanedione have been reported

previously.. 24 ' 62 ' 89

Metal analysis were done by the complexiometric titration method

of Lyle and Rahman 57 as described by Livingstone and Zimmermann.56

III. Determination of Associated Waters

There is some variation in the number of coordinated and hydrogen

bonded waters in lanthanide S-diketone complexes. Misra. 63,64,65 h as 9

Table 1.2

•.Analytical Data for Lanthanide Chelates of

4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedione L = C4H3SC(O)=CHCOF3

Complex Yield Colour Found (Calculated) (%) %C %H %Met

YL 3.2H20 75 cream 36.8 2.4 11.2 (36.6) (2.1) (11.3)

LaL3.2H20 80 pale yellow 34.9 2.4 16.2 (34.4) (1.9) (16.6)

CeL3.2H20 70 orange 34.6 1.9 16.8 (34.3) (1. 9) ( 16. 7)

PrL3.2H20 85 light green 34.4 2.3 16.6 (34 .4) (1.9) (16.8)

NdL3.2H20 85 pale blue 33.6 2.3 17.5 (34.2) (1.9) (17.1)

SmL3.2H2o 75 pale green 34.2 2.2 17.8 (33.9) (1.9) (17. 7)

EuL3.2H20* colourless 33.7 2.2 18.0 (33.9) (1.9) (17.9)

GdL 3.2H20 80 cream 33.8 2.2 18.4 (33.6) (1.9) (18.4)

TbL3 .2H20* pale cream 33.2 2.1 19.3 (33.6) (1.9) (18.5)

DyL3.2H20 65 pale green 33.7 2.2 18.7 (33.4) (1.9) (18 .9)

HoL 3.2H2o 70 cream 33.2 2.2 19 .2 . (33.3) (1.9) (19.1)

ErL 3.2H20 85 pink 33.3 2.0 19.4 (33.3) (1. 9) (19 .3)

TmL 3.2H2o 90 colourless 32.8 2.2 19.9 (33.2) (1.9) (19.S)

YbL 3.2H2o 75 colourless 33.1 1.8 19.8 (33.0) (1.9) (19.8)

*Prepared by the Eastman Kodak Company. 10

Table 1. 3

Analytical Data for Lanthanide Chelates of

4,4,4-trifluoro-l-(4'-bromophenyl)-1,2-butanedione

Complex Yield Colour Found (Calculated) (%) %C %H %Met

YL3.2H20 90 cream 36.2 1.9 8.7 (35. 8) (1.9) (8.8)

LaL3 .2H20 80 cream 34.4 1.8 12.9 (34.1) (1.8) (13.1)

CeL3.2H20 70 orange/brown 34.7 1.9 12.8 (34 .1) (1.8) (13.1)

PrL3.2H20 75 light green 33.8 2.2 13.4 (34.0) (1.8) (13.2)

NdL3.2H20 80 light blue 33.6 2.2 13.4 (33.9) (1.8) (13.6)

SmL3.2H20 75 cream 33.2 2.1 14.0 (33. 7) (1.8) (14.1)

EuL3.2H2o 70 pale yellow/ 33.1 2.1 14.4 green (33.7) (1.8) (14.2)

GdL 3.2H20 90 cream 33.9 2.0 14.2 (33.5) (1.8) (14.6)

TbL3. 2H20 85 pale yellow 33.3 2.0 15.0 (33.5) (1.8) (14.8)

DyL3.2H20 80 pale yellow/ 33.9 1.9 14.9 green (33.3) (1.8) (15.0)

HoL3.2H2o 75 cream 33.2 1.9 15.1 (33.3) (1.8) (15.2)

ErL3.2H20 75 light pink 33.4 2.0 15.2 (33.2) (1.8) (15.4)

TmL 3. 2H20 70 pale yellow/ 32.9 1.9 15.1 green (33.2) (1.8) (15.S)

YbL3.2H2o 85 off white 32.7 2.0 15.9 (33.0) (1.8) (15.9) 11

Table 1.4

Analytical Data for Lanthanide Chelates of 4,4,4-trifluoro-l-(3'-methylphenyl)-l,3-butanedione L = m-CH3C6H4C(O)=CHCOCF 3

Complex Yield Colour Found (Calculated) (%) %C %H %Met

YL 3.2H20 85 colourless 48.5 3.8 11. 2 (48.8) (3.5) (10.9)

LaL3.2H20 75 colourless 45.7 3.3 16.0 (46.0) (3.3) (16.1)

CeL3.2H20 70 orange/brown 46.0 3.0 16.0 (45.9) (3.3) (16.2)

PrL3.3H20 80 pale green 45.3 3.7 15.8 (44.9) (3.4) (16.0)

NdL 3.3H20 85 light blue 44.8 3.7 16.4 ( 44. 8) (3.4) (16.3)

SmL3.3H20 70 cream 44.6 3.2 16.9 ( 44. 4) (3.4) (16.9)

EuL3.2H20 75 colourless 45.1 3.2 17.2 ( 45. 3) (3.2) (17.4)

GdL 3.3H2o 90 colourless 43.7 3.6 17.4 (44.1) (3. 4) (17.5)

TbL3.3H 2o 75 pale yellow/ 43.8 3.2 17.7 green (44.0) (3.4) (17.7)

DyL 3.3H20 70 v pale green 44.0 3.2 18.2 ( 43. 8) (3. 3) (18.0)

HoL 3.3H20 80 cream 44.0 3.2 18.1 ( 43. 7) (3.3) (18.2)

ErL 3.3H20 85 pale pink 43.8 3.1 18.3 (43.6) (3.3) (18.4)

TmL 3.3H20 85 v pale green 43.2 3.2 18.8 (43.5) (3.3) (18.6)

YbL 3.3H20 80 cream 43.4 3.2 19.1 ( 43. 3) (3.3) (18.9) 12

Table 1.5

Analytical Data for Lanthanide Chelates of 4,4,4-trifluoro-1-(2'-methylphenyl)-1,3-butanedione L = o-CH3C6H4C(O)=CHCOCF 3

Complex Yield Colour Found (Calculated (%) %C %H %Met

YL 3.2H2o 40 cream 48.4 3.4 11.2 (48.8) (3.5) (10.9)

LaL3.2H20 65 cream 46.2 3.3 15.6 ( 46. 0) (3.3) (16.1)

CeL3.2H20 25 brown 46.1 3.0 15.8 ( 45. 9) (3.3) (16.2)

PrL3.2H20 70 light green 46.3 3.2 16.1 (45.9) (3.3) (16.3)

NdL 3.2H20 60 light blue 45.9 3.3 16 .3 ( 45. 7) (3.3) (16.6)

SmL3.2H2o so cream 45.8 3.2 16 .8 (45.4) (3. 2) (17.2)

EuL3 .2H20 65 cream 45.7 3.3 17.0 ( 45. 3) (3.2) (17.4)

GdL 3.2H20 30 cream 45.3 3.2 18.4 (45.0) (3.2) (17.9)

TbL3.2H20 75 pale yellow/ 44.6 3.1 18.2 green (44.9) (3.2) (18.0)

DyL3.2H20 SS cream 45.0 3.7 18.4 ( 44. 7) (3.2) (18.3)

HoL 3.2H20 so pale yellow 44.9 3.1 18.4 (44.6) (3.2) (18.6)

ErL 3.2tt2o 65 light orange 44.9 3.2 18.S (44.S) (3. 2) (18.8)

TmL 3. 2H20 65 cream 44.S 3.2 18.8 (44.4) (3.2) (18.9)

YbL 3.2H20 40 pale yellow 44.8 3.1 19.2 ( 44. 2) (3. 2) (18.9) 13

Table 1.6

Analytical Data for Lanthanide Chelates of 1,1,1-trifluoro-S,S-dimethyl-2,4-hexanedione

L = (CH3) 3CC(O)=CHCOCF 3

Complex Yield Colour Found (Calculated) (%) %C %H %Met

YL3.2H20 30 colourless 40.4 4.7 12.3 (40.6) (4 .8) (12.S)

LaL3.2H20 65 colourless 37.8 4.6 18.S (37.9) (4.5) (18.3)

CeL3.2H20 85 orange/brown 38.3 4.4 18.4 (37.9) (4.5) (18.4)

PrL3.2H20 70 pale green 38.0 4.6 18.8 (37.8) (4.5) (18.S)

NdL 3.2H20 65 lilac 36.9 4.4 19.1 (37.6) (4.5) (18.8)

SmL 3.2H20 75 colourless 37.3 4.4 19.3 (37.4) (4.4) (19.S)

EuL3.2H20 45 cream 37.6 4.5 20.1 (37.3) (4.4) (19. 7)

GdL 3.2H2o so colourless 37.2 4.2 20.3 (37.0) ( 4.4) (20.2)

TbL3.2H20 30 colourless 36.7 4.5 20.1 (36.9) (4.4) (20.4)

DyL3.2H20 35 colourless 36.7 4.4 20.8 (36.8) (4.4) (20. 7)

HoL 3.2H20 so pale orange 37.1 4.3 21.3 (36. 7) (4.4) (21.0)

ErL3.2H20 so pale pink 36.9 4.2 20.8 (36.6) (4.3) (21. 2)

TmL 3.2H2o SS colourless 36.9 4.2 21. 7 (36.5) (4.3) (21.4)

YbL 3.2tt2o 60 colourless 36.3 4.2 21.8 (36. 3) (4.3) (21.8) 14

reported the preparation of several lanthanide tris chelates of 4,4,4- trifluoro-1-(2l-thienyl)-l,2-butanedione and other fluorinated B-diketones 19,21,73,89 2 in the anhydrous form. One or two waters have been found by X-ray crystal structure to be coordinated in various lanthanide chelates of 2,4-pentanedione. Also found in some complexes with two coordinated waters was a third hydrogen bonded water. 1 , 20

Initially complexes prepared in this work gave variable carbon and hydrogen analyses that could correspond to oµe, two, or three associated waters. When the freshly prepared complexes were desiccated under vacuum for two hours over silica gel at room temperature, excellent agreement between the experimental analyses (including metal) and the calculated values for two waters was found in most cases.

As a confirmation it was attempted to determine the number of waters in complexes of 4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedione. The complexes were heated at 78°c under vacuum over silica gel or P2 0 5 • The weight loss was variable, ranging from 4 to 6%, which indicates the loss of two or three waters. There was, however, decomposition of some of the complexes so these results cannot be regarded as definitive. Chelates of neodymium and erbium were observed to change colour, from light blue to light green, and pink to light orange, respectively. This is presumably due to a change in coordination number due to the removal of the waters

(Part Three).

The structure of diaquotris(4,4,4-trifluoro-l-(3'-methylphenyl)-l,3- butanedione)erbium(III) hydrate prepared in this work was found by X-ray

crystal analysis (Part Two) to have two coordinated waters and a third

hydrogen bonded water. The recrystallisation from dichloromethane was

not done under dehydrating conditions and the crystals were not desiccated.

Although the structure indicates three waters, the third water is easily 15

removed to give two coordinated waters onlY. as indicated for the desiccated products by carbon, hydrogen and metal analyses.

IV. Experimental

Preparation of fluorinated 8-diketones

Sodium metal (3g) was reacted with methanol (25 mL), and the resultant sodium methoxide was suspended in dry diethyl ether (100 mL).

Ethyl trifluoroacetate (14.4g, 0.1 mol) was added slowly, with mechanical stirring, to the suspension. The appropriately substituted acetophenone

(0.1 mol) was added and the mixture was allowed to stand overnight at room temperature, in which time it turned red. The mixture was adjusted to approximately pH 6 by the addition of a saturated aqueous potassium hydrogen sulfate solution. A saturated aqueous solution of copper(II) acetate (200 mL) was then added with stirring. The diethyl ether was removed by heating on a steam bath. The green copper(II) chelate was

filtered off and washed with 95% ethanol (20 mL). The complex was

suspended in diethyl ether and hydrogen sulfide gas was passed for 30 min.

The copper sulfide produced was filtered off with the aid of cellulose

powder. The filtrate was dried over anhydrous sodium sulfate for 1 hr.

then evaporated to a small volume (30 mL) on a steam bath. Absolute

ethanol (25 mL) was added and the mixture was again evaporated down to

a small volume (25 mL). When the mixture had been cooled in ice,

crystals of the fluorinated 8-diketone separated out (approx. 30% yield).

Preparation of lanthanide chelates

The 8-diketone (1.0 g) was dissolved in 95% ethanol (30 mL), then

the stoichiometric quantity of 0.5 M aUDnonia was added slowly (5 min.).

A 50% excess of lanthanide salt hexahydrate (nitrate or chloride) was 16

dissolved in water (40 mL), then 95% ethanol (60 mL) was added. Dilute ammonia (0.2M) was added until the pH reached 5. The 8-diketone solution was then added dropwise (1-2 mL/min.) to the lanthanide salt solution with rapid magnetic stirring. During the addition of the 8-diketone the pH was maintained in the range 6.0 to 6.5 by the addition of dilute aI1U11onia or hydrochloric acid. The solution was filtered, cooled in ice, and the complex was precipitated by the dropwise addition of demineralized water

(100 mL). The microcrystalline product was collected on a sintered glass crucible, washed with demineralized water (100 mL), and dried in a vacuum desiccator over silica gel.

Two methods of recrystallisation were used:

(a) The complex was dissolved in alcohol (methanol or 95% ethanol)

and heated to boiling on a steam bath. Hot water was added

slowly till the solution just remained cloudy. It was then

allowed to cool, giving crystals of the complex (approx. 20%

yield).

(b) The complex was dissolved in the minimum amount of boiling

dichloromethane. As the solution cooled crystals of the

complex separated out (approx. 30% yield).

Analyses

Carbon and hydrogen analyses were carried out by Dr. Pham of the

Microanalytical Laboratory, University of New South Wales.

Metal analyses were carried out by the complexiometric titration method of Lyle and Rahman, 57 after digestion of the metal complexes (0.lg) with concentrated nitric (2 mL) and sulfuric (3 mL) acids. The resultant metal sulfates were dissolved in water and neutralized to pH 6 by the addition of aqueous aI1U11onia (SM). Sodium acetate (2 g)/acetic acid (SM, 1 mL) 17

was used as a buffer and the pH was adjusted to 5.8 by addition of dilute ammonia or acetic acid. EDTA (0.005M) was used as titrant with xylenol orange as indicator. The EDTA was standardized against A.R. zinc, also 88 with xylenol orange as indicator. PART TWO

CRYSTAL STRUCTURE OF DIAQUOTRIS(4,4,4-TRIFLUORO-l

(3'-METHYLPHENYL)-1,3-BUTANEDIONATO)ERBIUM(III) HYDRATE

I. Background

As well as many complexes of other metals, the structures of several 20 lanthanide 8-diketonates have been determined. In 1966 Cunningham et aZ. solved the structure of diaquotris (2,4-pentanedionato)yttrium(III) hydrate.

Each yttrium is bonded to eight oxygen atoms, contributed by three bidentate

8-diketonate groups and two water molecules (Figure 2.1). The average yttrium to 8-diketonate oxygen distance is somewhat shorter (2.37 A) than the average distance to the oxygen of the coordinated waters (2.41 !).

This distorts slightly the square antiprismatic coordination polyhedron

(Figure 2.2). The third water associated with the molecule is hydrogen bonded to one of the coordinated waters and links the molecules in pairs.

Phillips et aZ. 73 showed,that diaquotris(2,4-pentanedionato)lanthanum(III) has a virtually identical structure without the hydrogen bonded water of crystallisation. The structures of other lanthanide 2,4-pentanedionates 2 39 1 have been determined. For the neodymium, europium, and holmium complexes the structures were also found to be square anti-prismatic with eight coordinated oxygen atoms as in the yttrium complex.

The lanthanides, however, display variable coordination, and there are various examples of septacoordination. The coordination polyhedron for aquotris(2,4-pentanedionato)ytterbium(III) 21 was found to be a distorted capped trigonal prism, while aquotris(l-phenyl-l,3-butanedionato)yttrium(III) 18

(Figure 2.3) and aquotris(l,3-diphenyl-l,3-propanedionato)holmium(III) 92 had capped octahedral coordination polyhedra. The plane of the phenyl rings

1R 19

Figure 2.1. _Structure of diaquotris(2,4-pentanedionato) yttriwn(III) hydrate.

Figure 2.2. Square Antiprism of Coordinated Oxygens Surrounding the Europium Atom. 20

@=Y Q =O Q =C

Figure 2.3. Structure of aquotis-(1-phenyl-1,3-butanedionato) yttrium(III)

/I /c \~/ )c ,P--c, Plane 1 ,' C

Figure 2.4. Folding along 0-0 line in chelated ligands. 21

was not the same as that of the remainder of the ligand, the phenyl ring being rotated by'between 10 and 25 degrees. In all the structures cited there is folding along the 0-0 line of each chelating ligand (Figure 2.4). 18 89 The dihedral angle between the planes varies from 4.4 to 23 degrees.

The structure of one of the complexes used in this work was reported in 1975. 89 Diaquotris(4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedionato)- europium(III) was found to be eight-coordinate around the europium with two coordinated waters. The crystals decomposed, so only a general outline of the molecular geometry was obtained. The eight oxygen atoms form a square antiprism as shown in Figure 2-2. It may be considered as a cube with relative rotation of opposite faces by 45 degrees. The shaded lines connect two oxygen atoms of the same B-diketonate. Ligands A and B have their two coordinated oxygens on different squares, while Chas them both on the same square. This means that all the 8-diketonates are not identical ligands. A and B fold along the 0-0 line by 20 and 23 degrees, respectively, while the europium is almost coplanar with the other five atoms in the

B-diketonate ring of ligand C. Ligands A and B lie approximately in one plane; the angle between this plane and the plane of group C was 80 degrees.

The thienyl groups rotate so that each of the sulfur atoms is adjacent to the nearest coordinated oxygen of the same group.

II. Experimental

Crystal data: formula c33H30ErF9o9 microanalysis Found: 43.5% C, 3.2% H

Calculated for 3H 2o: 43.6% C, 3.3% H. molecular weight 908.8 5 monoclinic P2/c (C 2h, No. 14)

0 a 11.641(2), b 16.479(3), c 18.967(a) A 22

B 91. 80(1)0

03 V,3637(1) A -3 p 1.654, p (Z =4) 1.660 g cm m C µ(Mo Ka) 24.3 cm-l

recrystallised from dichloromethane

Data collection, solution and refinement of the structure

The data were collected using an Enraf Nonius CAD4 automatic four circle diffractometer (Mo Ka radiation, graphite monochromated); the prismatic crystal measured 0.23 by 0.25 by 0.17 mm. Of 5050 unique reflections, 4136 were considered observed with I> 3.0cr(I) and were used for the structure refinement. The data were corrected for absorption.

The position of the metal atom was located by heavy atom (Patterson) methods. The remaining non-hydrogen atoms were located by Fourier syntheses. No extinction correction was necessary. Scattering factors for neutral atoms were used. 38

The structure was refined by the block-diagonal least-squares method.

Initially isotropic temperature factors were used for all atoms and all data were included in the refinement. The value of R (Equation 2.1) dropped from 0.185 to 0.099 in one cycle of refinement.

R = Equation 2.1 F rl 0

At this stage, anisotropic thermal parameterisation was applied to all

52 non-hydrogen atoms and after a cycle of refinement the R factor was 0.089.

It was expected that the improved modelling of the thermal motion would

cause a larger decrease in the R factor than was observed. Inspection of

a difference Fourier map showed that large peaks of residual electron 23

density were associated with the fluorine atoms of each -cF3 group.

Obviously the -CF3 groups were disordered. Disorder has been observed in 6 19 structures of similar compounds, ' and no attempt was made to model the disorder in those cases. Another discernible, geometrically reasonable orientation of each -cF3 group was found, and each fluorine atom was replaced by two half occupancy atoms: one at the original position and one at the location of the peak in the difference map. The atoms at the new fluorine positions were assigned an estimated value of isotropic thermal. parameter. An attempt to refine occupancies and isotropic thennal parameters was unsuccessful, probably because of correlation between parameters of such closely separated atom fragments in the model structure. For subsequent cycles of least-squares refinement, the occupancies of each fluorine site was held at 0.5, and the thermal parameters and positions were not refined.

After a cycle of refinement using only high-angle data ((Sin 0/A) >

0.3), a difference Fourier map, based on these data (R=0.049), revealed the positions of several hydrogen atoms which were added to the model.

Unfortunately not all the methyl hydrogens could be unequivocally located so they were not included. A further attempt to refine manually the thermal parameters of the fluorine atoms was unsuccessful.

After further refinement using all data, the final values of Rand R w (Equation 2.2) were 0.059 and 0.091, respectively, for 4136 data. In the

final cycle, the maximum parameter shift/standard deviation was 0.90. A -3 final difference Fourier map showed peaks of approximately 1 electron A around the fluorine positions but no other significant peaks.

R Equation 2.2 w

The atomic positions and thermal parameters obtained are listed in

A·.,)Pn~-4v f' 24

Figure 2.5. Structure of diaquotris (4,4,4-trifluoro-1-(2'-methylphenyl) 1,3-butanedione)erbium(III) hydrate. 25

III. Results and Discussion

The molecular complex was found to be eight coordinate. All three S-diketonates act as bidentates. The remaining two sites in the coordination sphere are occupied by water molecules. A third water molecule was found to be hydrogen bonded to one of the coordinated water molecules. This water is readily lost under vacuum over silica gel at room temperature to leave only the two coordinated waters. A view of the molecule is shown in Figure 2.5. Each atom is represented by an ellipsoid with the relative size and orientation consistent with the thermal parameters at a 50% probability level.

There are two commonly observed geometries of eight coordination -

square antiprismatic or dodecahedral. Often the observed structure is between these two extremes and the choice of nearest geometry is not obvious. This is particularly so in mixed-ligand complexes, so the

designation must be based on the overall approximation to the ideal.

The two possible configurations for the molecule are shown in Figure 2.6.

The atoms OlA, 02A, OlC and 02C are planar, and this plane is almost

parallel to the plane formed by the atoms OlB, 02B, OD and OE (the angle

between the two planes is 2°). The distortion observed may be

attributed to the presence of chemically different ligands bonded to the

same metal atom.

The presence of two waters on one side of a 'square' distorts it

asymmetrically; the corners are distorted by as much as 6° from 90°.

The other plane containing ligands A and C is distorted into a rhombus

with the angles an average of 4° from 90°. The lengths and angles are

given in Tables 2.1 and 2.2 The two squares are rotated by approximately

45° as required for a square antiprism. This can be seen in Figure 2.5. 26

square antiprism

dodecahedron

Figure 2.6. Idealised square antiprismatic and dodecahedral coordination polyhedra for the complex. 27

Table 2.1

Oxygen to Oxygen Interatomic Distances in the

Distorted Square Antiprism

0 OlA - 02A 2.13 A 01B - 02B 2.75 A 02A - 02C 2.84 02B - OD 2.95

02C - OlC 2.73 OD - OE 2. 72

OlC - OlA 2.79 OE - 01B 2.64

OlA - OD 2.87 02C - 01B 2.85 OD - 02A 2.98 01B - OlC 3.14

02A - OE 3.08 OlC - 02B 2.83

OE - 02C 2.93 02B - OlA 2.88

Table 2.2

Angles arol.llld the square faces of the distorted

square antiprism

01A - 02A - 02C 93.1° 01B - 02B - OD 83. 7° 02A - 02C - OlC 85.3 02B - OD - OE 89.6

02C - OlC - OlA 94 .2 OD - OE - 01B 90.4 OlC - 01A - 02A 86.3 OE - 01B - 02B 95.7 28

Although inconclusive in this example, Lippard and Russ55 give a possible means of determining whether the geometry is square antiprismatic or dodecahedral. They suggest:

(a) compute the trapezoidal best planes for a supposed

dodecahedron;

(b) calculate the value for the angle of intersection between

these assumed planes;

idealized dodecahedron and 77.4° for the idealized square

antiprism.

The angle obtained between the planes: 02A, OlB, 02B and 02C; and OlA

OlC, OD and OE; is 84.6~ indicating the coordination polyhedron is midway between dodecahedral and square antiprismatic. Considerable deviation from the 'best planes' was observed, which makes this value less significant. The coordination geometry is observed to best approximate a distorted square antiprism.

There is some variation of the erbium to oxygen atom distances.

The erbium to oxygen distances are approximately 0.04 A greater for ligand B than for the respective bonds in ligands A and C. The distances in ligands A and Care virtually identical (Table 2.3). Each ligand bonds asymmetricall~ with the Er-02 bond being about 0.02 A longer than the Er-01 in each case. Such variations have been observed before for

2,4-pentanedionate complexes, 1 ' 2 ' 20 ' 73 ' 92 which are non-fluorinated, so the asymmetrical bond lengths are presumable due to steric effects between the ligands, and not to the electron withdrawing nature of the

-cF 3 group. Ligand Bis in the same 'square' as the two coordinated waters, so the Er-0 bonds in ligand B have 'stretched' to a similar

length to the Er-0 in the coordinated waters, presumably to minimize 29

Table 2.3

Erbium to Oxygen Atom Interatomic Distances

0 0 Er - OlA 2.286(8) A Er - 02A 2.310(7) A Er - 01B 2. 328(8) Er - 02B 2.355(8) Er OlC 2.286(7) Er 02C 2. 325(7) Er - OD 2. 388(7) Er - ow 2. 352 (7)

Table 2.4

Angles around the Erbium Atom

OlA - Er - 02A 72. 9 ° 01B - Er - OlC 85.7°

01B 146.6 02C 75.3

02B 76. 8 OD 107.5

OlC 75.2 OE 68.8

02C 122.5 02B - Er - OlC 75.3

OD 75.9 02C 135.3

OE 138.4 OD 77.0

02A - Er - 01B 140.3 OE 116.3

02B 146.2 OlC - Er - 02C 72. 7

OlC 110.5 OD 143.5

02C 75.5 OE 144.8

OD 81.3 02C - Er - OD 142.9

OE 79.0 OE 77.5

OlB - Er - 02B 71.9 OD - Er - OE 70.0

N.B. All errors 0.3° 30

distortion. Due to the longer bond lengths ligand B also has a slightly reduced 0-Er-0 angle at 71.9° compared with 72.9° and 72.7° for groups

A and C. The angles are listed in Table 2.4.

The atoms 01, 02, Cl, C2, C3, C4 and CS are co-planar (plane 1) for all three chelating ligands. In each case the entire chelate ring is not planar, as the metal atom is considerably out of the plane.

This can be interpreted as folding along the 0-0 line (Fig. 2.4).

Ligands A, Band Care folded by 10.4°, 27.7° and 19.2°, respectively.

Both ligands A and C, which are ais to one another on the same 'square' face of the distorted square antiprism fold away from each other.

Ligand B folds away from the two coordinated waters, presumably due to the greater steric influence of the coordinated waters, compared with that of the other two chelating ligands (Table 2.5). The angle between plane 1 of both of the chelating ligands A and C is 54.0°. This is markedly reduced from the angle between the planes Er, 0lA, 02A; and Er,

0lC, 02C which is 82.2°. The observed difference in these angles represents the folding of the ligands away from each other. Plane 1 of ligand Bis only 14.5° from plane 1 of ligand A, and 39.5° from plane 1 of ligand C. This occurs as ligand Bis 'opposite' ligand A (Fig. 2.7), and both groups Band C fold towards each other. This is similar to what was found by Cunningham et ai. 20 for diaquotris(2,4-pentanedionato) yttrium hydrate.

Each m-methylphenyl group is co-planar (plane 2) and is rotated out of the plane of the rest of the ligand. For ligands A, Band C the rotation is 29.7°, 21.2° and 10.4°, respectively. The rotation observed for ligand C is less than for A or Bas it is sandwiched between

them. The methylphenyl group of ligand Bis close to the methylphenyl

group of ligand C, which may reduce the rotation in comparison with 31

Figure 2.7. Diagranunatical representation of molecule. 32

ligand A (Fig. 2.7).

The interatomic distances and angles of the three chelating ligands are summarized in Tables 2.5 and 2.6. All the angles are identical within the experimental error. Figure 2.8 shows the numbering system of the B-diketonates. The bonds that are predicted to show aromatic character, in the phenyl ring and B-diketonate ring, are observed to have shorter bond lengths than bonds which are predicted to be non-aromatic

(C4-C5, Cl-C6, C8-C12).

The third, hydrogen-bonded, water in the molecule, OW, was

2.62(1) A from coordinated water OE, with an Er-OE-OW angle of 131.2(5) 0 •

Cunningham et aZ. found that, in the similar yttrium 2,4-pentanedionate complex, the third non-coordinated water was hydrogen-bonded to the equivalent water in the next molecule; thus the molecules were linked in pairs. The distance between the two hydrogen-bonded non-coordinated

0 waters in the complex was 2.90 A. For the same bond in this structure the length was 3.48 A, which seems too long for hydrogen bonding to occur. The hydrogen-bonded water was, however, 2.94 and 3.05 A from 02C and 02A, respectively, in the next molecule, so some association between them may have occurred. The hydrogen atoms of the waters were not located so unequivocal indications of their bonding could not be obtained.

There are 17 isomers for eight-coordination of three bidentates 46 and two monodentates. This structure has the same isomerism as the

2 , 4 -pentane di one c h e 1 ates o f yttrium,. 20 l ant h anum, 73 an d neo d ymium.. 2

A diagram of the isomer is given in Figure 2.7. The complex diaquo-

tris(4,4,4-trifluoro-l-(2'-thienyl)-1,3-butanedionato)europium(III)

is a different isomer. 89 The two waters are on the same 'square' face

as for the other isomer, but instead of being adjacent they are at

opposite corners of the square. Two of the chelating ligands bridge 33

Table 2.5

Interatomic Distances in Chelating Ligands

A B C

0 0 0 01 - Cl 1.23(1) A 1.23(1) A 1.24(1) A Cl - C2 1.40(2) 1.46(2) 1.45(2) C2 - CJ 1.32(2) 1.30(2) 1.31(2) C3 - 02 1.29(1) 1.27(1) 1.28(1) Cl - CS 1.48(2) 1.52(2) 1.50(2) CJ - C4 1.56(2) 1.55(2) 1.55(2) CS - C6 1.38(2) 1.36(2) 1.35(2) C6 - C7 1.45(2) 1.45(2) 1.41(2) C7 - CS 1.44(2) 1.39(2) 1.39(2) CS - C9 1.33(2) 1.35(2) 1.35(2) C9 - ClO 1.51(2) 1.45(2) 1.40(2) ClO- CS 1.39(2) 1.36(2) 1.40(2) C7 - Cll 1.46(2) 1.48(2) 1.48(2)

C11

C7I C6/I " ci /CS C9 /01-C1"/ " C10 / Er C2 "'-02-c3/ "'C4

Figure 2.8. Numbering system used for the 8-diketones. 34

Table 2.6

Angles Around the Chelating Ligands

A B C

Er - 01 - Cl 138° 134° 138°

01 - Cl - C2 122 122 121

Cl - C2 - C3 124 122 122

C2 - C3 - 02 130 131 131

C3 - 02 - Er 131 125 129

C4 - C3 - 02 112 113 112

C4 - C3 - C2 119 117 117

CS - Cl - 01 117 117 119

CS - Cl - C2 121 121 121

Cl - CS - C6 119 119 118

Cl - CS - ClO 120 121 123

CS - C6 - C7 124 124 124

C6 - C7 - CS 114 113 115

C7 - CS - C9 125 125 123

CB - C9 - ClO 120 119 121

C9 - ClO - CS 117 118 118

ClO - CS - C6 121 121 119

Cll - C7 - C6 122 121 122

Cll - C7 - CS 124 127 124

N.B. All errors 1°. 35

the 'square' faces, and the remaining chelate bonds on the same 'square'.

A representation is given in Figure 2.2.

A manifestation of the lanthanide contraction may also be observed by a comparison of the lanthanide-oxygen interatomic distances for various chelates. The average bond lengths are found to decrease in the order: La> Nd> Eu > Y >Ho> Yb. This conforms exactly to the order of decreasing radii of the tervalent ions due to the lanthanide contraction. The bond lengths are found to vary from 2.38 X for the lanthanum chelate to 2.23 ! for the ytterbium chelate. 1 , 2, 20 , 73 , 89 The result obtained in this work for erbium (2.32 A) comes between holmium (2.33 A) and ytterbium (2.24 A). Yttrium (2.38 A) is slightly longer than holmium.

IV. Programs Used

FOURIN - Written by D.C. Craig, U.N.S.W. to calculate Patterson

and Fourier syntheses.

STRFAC - Written by D.C. Craig to calculate structure factors.

EXFFT - A program to calculate fast Fourier transform. Part 59 of the MULTAN80 package.

SEARCH - A program to find peaks in electron density maps. Part

of the MULTAN80 package.

BLOCKLS-Adapted by D.C. Craig from ORFLS 8 for full-matrix or

block diagonal least squares refinement.

FANDEB - Adapted by D.C. Craig from ORFFE9 to calculate

molecular geometry. The errors were calculated from

the inverse matrix of the last cycle of least squares

refinement. 36

PLANES - Adapted by D.C. Craig for calculating best least

squares planes using the method of Schomaker et az. 79 41 ORTEP - Written by C.K. Johnson to illustrate crystal struc-

tures including a representation of thermal motion. PART THREE

VISIBLE SPECTRA OF THE LANTHANIDE CHELATES

I. Background

Compounds of tervalent lanthanides are either very pale or colourless.

The ions La3+ (4fO) and Lu3+ (4f14) possess closed-shell electronic configurations and display no absorption bands. The ions Ce3+, Gd 3+ and 3+ Yb absorb entirely in the ultraviolet region and display no absorption

-1 bands in the visible region (12000 to 30000 cm ). The remaining tervalent ions absorb partially in the visible region. The narrow, low intensity absorption bands of these ions have been studied by a number of workers,10, 27 , 4o, 43 , 44 , 67 , 7l,9l and most of the electronic transitions have been assigned. These line-like absorption bands result from inner 4f transitions of a predominantly electric dipole character that for a free ion are Laporte forbidden, but are allowed by interactions produced by externa1 ligan d fi e ld s tath mi x i n states o f opposite. pari·t y. 42,71,90

The energies of the bands in the spectra of lanthanide compounds are affected only to minor extents when the chemical environment is changed; this can be explained in terms of the effective shielding of the 4f electrons by the outer 5s2 and 5p6 shells. When spectra of lanthanide complexes are compared with those of the aquated lanthanide ions, three changes are observed, all of which are related to alterations in the

strength and symmetry of the ligand field. These changes are:

(a) small shifts usually towards lower frequencies;

(b) splitting of certain bands into several small maxima;

37 38

Those bands that are particularly susceptible to splitting and intensity changes are ter~ed "hypersensitive11 • 42 , 44 , 45 , 66 , 67

Although these effects are useful in determining the synmetries of complex species in solution, and thus suggesting coordination numbers and molecular structures, they are far from definitive for the lanthanide ions, since the order of perturbation is: crystal field< spin-orbit coupling< inter-electron repulsion. The hypersensitive transitions that are observed in the electronic spectra of neodymium, holmium, and erbium have been studied both theoretically and experimentally. The variations are attributed to the action of an inhomogeta:>uselectromagnetic field from the medium. 51 The intensities of normally weak quadrupole transitions increase as a result of the inhomogeneous field. Judd43 has also suggested that the hypersensitive transitions are strongly affected by changes in the symmetry of the ligand field acting on the lanthanide ion. 44 45 . Karraker ' has confirmed the theory experimentally. The hypersensitive transitions have been correlated with coordination numbers 6, 7, and 8 for a- diketonates o f N d 3+ , H o 3+ , an d Er 3+ •

Henrie et al. 34 attributed the hypersensitive transitions to metal- ligand covalency via charge transfer. They made three generalisations concerning the intensities of the transitions:

(a) An increasing basic character of the coordinating ligand

results in increasing absorption intensity.

(b) Decreasing metal-ligand bond distances result in intensity

enhancement.

the greater the enhancement of intensity.

The experimental criterion for the existence of a hypersensitive transition

is if I~J I < z. 42 39

II. Results and Discussion

The visible spectra of 36 lanthanide chelates of the fluorinated S-

diketones in 95% ethanol have been measured. The extinction coefficients

-1 obtained over the range 13000 to 30000 cm for LnL3 .2H2o (Ln = Pr, Sm, Eu,

Tb, Dy, and Tm; L = TTB, m-MPB, and DMH) and all 15 complexes of neodymium, holmium, and erbium are listed in Tables 3.1 to 3.9. The

calculated electronic energy levels for the free ion, the experimental results for the terpositive lanthanide ions obtained by Carnall et az. 11- 14

and the experimental results for the lanthanide nitrates in water, obtained

in this work, are included for comparison.

The four fluorinated S-diketones that are substituted with an

aromatic ring as R, R = 2'-thienyl, p-bromophenyl, m-methylphenyl, and

o-methylphenyl, have a large ligand absorption, so that when they were

chelated to the lanthanides no bands due to the lanthanide absorptions

-1 could be detected above approximately 24000 cm For complexes of 1,1,1-

trifluoro-5,5-dimethyl-2,4-hexanedione, which have a non-aromatic tertiary

butyl R group, ligand absorptions do not obscure the lanthanide absorptions

-1 till about 28000 cm , so many more lanthanide absorptions could be

observed.

The observed frequencies of the line-like spectra of the complexes

are very close to the calculated frequencies listed by Carnall et aZ.,

and the experimental results obtained for the nitrates. The intensities

of the absorptions were essentially the same for the nitrate and complexes

of the same lanthanide. Variations in the intensities occurred when:

(a) the lanthanide absorptions occurred in the 'tail' of the

ligand absorption, where they were observed as shoulders

or small peaks on the ligand absorption curve;

(b) when hypersensitive bands were involved. ~

(1.28)

(0.82)

(0.18)

(3.84)

(6.13)

(7.96)

thanol

)

95%

16560 16860 20660 17060wsh(cl.0) 17480

21190

Pr(DMH)~.2H20

22520wsh(c6.5) E(cm-

22320

88)

(cl.2) (0.25)

(0.91) (1.57)

(11. (3.94) (10.74)

(7.89)

Ethanol

Chelates

95%

22500sh

22260

16570sh 16860 17060wsh 20620 17470

Pr(m-MPB).2H20

21190

E(cm-1)

.11)

(1.17) (0.30)

(11.40)

(c0.9) (1.64)

(4.38) (13

(9.08)

Praseodymium

3.1

Ethanol

the

95%

22570sh

16860 17130sh 20660 22350 17510

21250

Table

Pr(TTB)2.2H

E(cm-1)

r6560wsh

)

79)

31)

Spectra

H2o

.6H

(1.

(5.45) (0.85)

(5.23)

(11.

)

demin.

Visible

Pr(N0 16970 20700

21270

E(cm-1)

{16810sh

(aq)

22520 22570

21500

exptl. 21300

Pr 16840 20750 E(cm-1)

(aq)

22535

21500

Pr 16840

calculated 21330

20706 E(cm-1)

4 2

Electronic

Transition 41

Table 3.2

Visible Spectra of the Neodymium Chelates

3 3 11 Electronic Nd +(aq)11 Nd + (aq) Nd(N0 3)3.6HzO Nd(TTB).2H2o Transition calculated experimental in demin. H2o in 95% ethanol E(cm-1) E(cm-1) E (cm-1) E E(cm-1) e:

4 4 13460 13500 13500 (6. 9) 13390 (6 .3) 19/2 -+ F7 /2 4 13565 13650 (4.2) 13610sh (5.0) 53/2 13500

(1.6) 4 {14660 F9/2 14854 14700 14730 (0.5) 14810 (1.6)

2 Hll/2 16026 15870

li70~0sh (34) 4G5/2 17167 17300 17330sh (5. 8) 7150 (41) 7229sh (39)

2 {17330 (20) G7/2 17333 17460 17390 (7.3) 17480 (27)

2 K13/2 19018

(9.8) 4 { 19170 (4.7) {18970 G7/2 19103 19160 19040 (8.1) 19230sh (4.1) -

4 { 19570 (l.8)1 G9/2 19544 19550 19500 (4.5) 19640sh (1.5) 2 K15/2 21016 21000 21050 (0. 8) 20960 (2.8)

2K (2.4) 9/2 21171 21300 21320 (0.9) 21270 4 Gll/2 21563 21650 21640 (0.7) 21740 (2.7) 2 pl/2 23140 23259 23360 (1.1) 23310 (5 .1) 42

Table 3.2 - Continued

Nd(m-MPB) ~~-2Hr° Nd(o-MPB) 3.2H 7 0 Nd(p-BPB).2H2o Nd(DMH)~.2H 2o in 95% et ano in 95% etiianoI in 95% ethanol in 95% ~thanol E(cm- 1) e: E(cm- 1) e: E(cm-1) e: E(cm-1) e:

13330 (6.0) } 13380 (4.2) 13400 (5. 4) 13380 (3. 9) 13570 (5 .4)

14640 (2.0) 14610 (0 .5) { 14640 (0.5) 14670 (0.5) 14790 (2.0) 14760 (0.5) J . 14770 (0.5) 15940 (0.3) 15990sh (0.6) 15940 (0.4)

16750wsh (10) 16760wsh (9) 17040sh (30) 17020sh (26) 17010wsh (29) 17040sh (24) 17130 (37) 17110 (32) 17140 (38) 17130 (28) 17220sh (39) 17180 (35) l 7210sh (31) 17210 (27)

17330 (19) 17360 (15) 17340 (20) 17360 (14)

17470 (30) 17450 (28) 17480 (28) 17480 (24)

18950 (10) 18830wsh (4.5) 18960 (8.5) 18940 (6.4) 19010wsh (8.3) { 18910 (7.0) f 19060 (8.8) 19020wsh (5.4) 19060wsh (7.1) 19020wsh (5. 6) 19090sh (4.3) 19080sh (4 .5)

19440 (5. 2) 19460 (2.6) 19480 (4.8) 19450 (2. 7)

20930 (3. 7) 20940 (1.0) 20910 (3. 8) 20870 (1.1)

21240 (0.9) 21230 (3.5) 21280sh (3.9) 21270 (2.4)

21680 (0. 7) 21740 (0. 9)

23260 (6.6) 23190 (2. 9) 23280 (8 .0) 23190 (1. 6)

~ ~

w w

23) 23)

28) 28)

27) 27)

E E

1.15) 1.15)

(1. (1.

(0.64) (0.64)

(0.58) (0.58)

(1.29) (1.29)

(1.13) (1.13)

( ( (1.21) (1.21)

(0.79) (0.79) (1. (1.

(1. (1.

(4.30) (4.30)

Ethanol Ethanol

) )

95% 95%

20860 20860

20060sh 20060sh

21140 21140

20570sh 20570sh

18770sh 18770sh 22220 22220

20380 20380

21620 21620

in in

23920 23920

22680sh 22680sh

18960 18960

E(cm-

Sm(DMH)3.2H20 Sm(DMH)3.2H20

E E

27) 27)

71) 71)

(0.12) (0.12)

(0.73) (0.73)

(0.64) (0.64)

(1. (1.

(0.88) (0.88)

(0.27) (0.27)

(0.76) (0.76)

(7. (7. (0.17) (0.17)

(0.78) (0.78)

Ethanol Ethanol

95% 95%

18810sh 18810sh

20370 20370

21570 21570

20080sh 20080sh

in in

21190 21190

20900 20900

20620sh 20620sh

18930 18930

22200sh 22200sh

23830 23830

Sm(m-MPB).2H20 Sm(m-MPB).2H20

E(cm-1) E(cm-1)

Chelates Chelates

1) 1)

71) 71)

41) 41)

37) 37)

E E

(1.20) (1.20)

(cl. (cl.

(1. (1.

(0. (0.

(0.27) (0.27)

(2.16) (2.16) (1.14) (1.14)

(12.47) (12.47)

Ethanol Ethanol

Samarium Samarium

95% 95%

3.3 3.3

20900sh 20900sh

20620wsh 20620wsh

22270sh 22270sh 20410 20410

21620 21620 20080wsh(c0.5) 20080wsh(c0.5)

in in

21320sh 21320sh 23870 23870

18940 18940

18820sh 18820sh

the the

Sm(TTB)2-2H20 Sm(TTB)2-2H20

E(cm-1) E(cm-1)

of of

Table Table

0 0

E E

.61) .61)

H2o H2o

.6H

(0.03) (0.03)

(0.56) (0.56) (0.05) (0.05)

(0.46) (0.46)

(0.43) (0.43) (0.01) (0.01)

(0 (0

(0.03) (0.03)

(0.19) (0.19)

Spectra Spectra

)

demin. demin.

22620 22620 20870 20870

18900 18900 22220 22220

17860 17860

in in

24100 24100

23950sh 23950sh

Sm(N0

E(cm-1) E(cm-1)

Visible Visible

11 11

(aq) (aq)

3+ 3+

22700 22700

18900 18900

21600 21600 21600 20050 20050 20040

21100 21100

24050 24050

20800 20800

22200 22200

exptl. exptl.

Sm Sm

E(cm-1) E(cm-1)

11 11

) )

(aq) (aq)

+ +

18832 18832

17924 17924 17900

20014 20014 21650 21650

21096 21096

24101 24101

22706 22706 20627 20627

22098 22098

20526 20526

E(cm-

calculated calculated

11/2 11/2

13/2 13/2

P)S/2 P)S/2

5/2 5/2

F3/2 F3/2

4 4

FS/2 FS/2

G9/2 G9/2

G7/2 G7/2

T9/2 T9/2

M15/2 M15/2

4 4

4G 4G

4 4

4 4 4 4

4 4

P, P,

6 6

-+ -+

I I

5/2 5/2

4H 4H

Electronic Electronic Transition Transition ,I:'- ,I:'-

52)

(c4.8)

(7.52)

(13.0)

(7.

thanol

95%

in 24810

24570wsh

26670

27550 E(cm-1)

Sm(DMH)i.2H

(11.5)

Ethanol

included.

95%

in 24800

E(cm-1) Sm(m-MPB).2H2O

not

are

Ethanol

95%

E(cm-1) Sm(TTB)2.2H2O

experimentally,

continued

82)

73)

H2o

3.3

(

(0.58)

(0.24) (0.

(0.68)

observed

in.

)3.6H

Table

not

24600 E(cm-1) Sm(NO 24880

25640

26740

27550

but

)

+(aq)

24570 sm E(cm- exptl. 24950

26750

25650 27700

calculated,

were

(aq)

that

24562 Sm calculated E(cm-1) 24999

26660

25638 27714

L13/2

L15/2 p3/2

p7/2

D3/2

6 4

Transitions

5/2

Electronic

Transition

N.B.

411 Table 3.4

Visible Spectra of the Europium Chelates

3+ 3+ Electronic Eu (aq) Eu (aq) Eu(N03)3.6H o Eu(TTB) 3.2H20 Eu(m-MPB)f 2Hf0 Eu (DMH) 3. 2H20 Transition calculated exptl. in demin H20 in 95% Ethanol in 95\ Et ano in 95% Ethanol E(cm- 1) E(cm-1) E(cm- 1) E E(cm-1) E E(cm-1) E E(cm-1) E

7F -+ SF 16936 16920 16950 (0.02) 1 0

7F -+ 5D 17286 17277 17240 (0.26) 17230 (0.21) 0 0 - 17260 (0.39) 7 5 (0.41) 18530sh (0.35) 18550 (0.56) F -+ D e 18676 18691 18730 (0 .02) u8530sh 1 1 18710 (0.66) 18700 (0.56) 18730 (0.85) 7 5 F -+ D e 19026 19028 19060 (0.15) 19020 (0.48) 19020 (0. 31) 19010 (0.58) ~ 0 1 VI 20610sh (0.53) 20630sh (0.48) 20590sh (0.68)

7F -+ 5D 1 2 21149 21164 - 21250 (0.83) 21280sh (0.72) 21210sh (0 .81)

7 F -►5D 21499 21519 21570 (0.09) 21460 (4,97) 21440 (4 .91) 21530 (4 .65) 0 2 7 S F1 -+ l)J 24040 24038 24120 (0.04)

7F -+ 5D 24389 24408 0 3 7F -+ SL 25025 25000 1 6

7F SL 25400 25430 (2.78) 25410 (16.7) 0 -+ 6 25375 .i:-

(0.86)

(5.05)

Ethanol

)

95%

(crn-

20530

26550sh E

Tb(DMH)3.2Hz0

(1.09)

Ethanol

)

95}

(cm-

20530

Tb(rn-MPB)3.2Hp

Chelates

(1.67)

.2Hz0

Ethanol

3.5

Terbium

95%

the

20590

E(cm-1)

Tb(TTB)

Table

04)

27)

H2o

(0.

Spectra

dernin

26510 E(crn-1)

Tb(N03)3.6HzO

Visible

(aq)

exptl.

20500 20560

Tb 26500 E(cm-1)

(aq)

E(cm-1) calculated

20545

26336

Tb3+ 26425

c;6

SI)

6 4

Electronic

Transition ~

......

37)

59)

(0.56) (0.99) (0.24) (1.

(1. (1.45)

(c2.2)

(3.50)

(7.83)

Ethanol

95%

21230sh 12500 in 13190

E(cm-1) 22030 22170sh

Dy(DMH)3.2H20 23500sh

25050wsh

25810

27400

29)

36)

.61)

(0.14)

(0 (1.

(2.

(2.65)

(3.06)

Ethanol

95%

12510

13170

Dy(m-MPB)3.2H20 21190sh

E(cm-1) 22030 22140sh

23510sh

Chelates

23)

(0.

(0.68) (cl.

(2.17)

(2.55)

(c3.0)

3.6

Ethanol

Dysprosium

95%

the

Table

in 13200

Dy(TTB)3.2H20 21180wsh 12350 E(cm-1)

22220sh

23530wsh

{22080

20)

.10)

H2o

(0.07)

(0.02) (0.26)

(0.10)

(0. (0.81)

Spectra (1.89) (0.

demin

12410

13200 Dy(N03)3.2H20

Visible E(cm-1)

21140 23410

22220

25250 25840

27400 26310

)

+(aq)

12400

exptl. 13250 Dy

E(cm-

21100

22100

23400

25800

26400 25800

27400

(aq)

Dy3+ 12432 E(cm-1) 13212

13760

calculated

21144

22293

25754

23321 26341 27254 26365 25919 27219

27503

3/2

15/2

13/2

FS/2

F3/2

Fl/2 F9/2

F7/2 K17/2

P, p5/2

Gll/2

M21/2

M19/2

4 4 4 4 4 4 4

(

Electronic

Transition

15/2-+

6 6 48

Table 3.7

Visible Spectra of the Holmium Chelates

3+( ) 11 3 11 Electronic Ho aq Ho +(aq) Ho(N03) 3 .6H20 Ho (TTB J.3· 2H20 Transition calculated experimental in demin. H2o in 95% ethanol E (cm- 1) E(cm-1) E(cm-1) E E(cm-1) E 15220 (1. 13) 15200 (1.13) 15519 15500 { 15310 (cl.2) 15300wsh(cl. 2) 15620 (2.40) 15630 (2.40)

{ 18210sh (c2 .1) 18400wsh(c2.1) 18354 18500 18400 (~2.9) 18520wsh(c2.9)

18612 18500 18620 (5.60) 18660 (3.95)

20410sh (0. 41) 20330wsh(c0.9) 20673 20600 { 20620 (2 .15) 20580 (1.85) 20700wsg(cl.2} 20700sh (1.57) 20880 (0.57) 21010sh (1.99)} 21130 21100 21140 (0.95) { 21190 (2.02)

21370 (6.48) 21308 21370 21410 (0. 95) · { 21470 (6. 38)

21690 ( 44 .6) 22094 22100 22120 (4.67) { 22150 (106. 9)

22375 22220 (4.71) 22780 (2.23)

23040sh (2.62) 23700 (0.99) 23280wsh(c4.1) 23887 23950 { 24040 (2.98) t23580 (7.36) 23700sh (7.19) 23810 (6 .65)

25826 25800 25710 (0.37)

3K 26117 26200 25970 (0 .58) 7

(5G,3H)5 27653 27700 27620 (2.64) 3I-l, 27675 27700 \) 49

Table 3.7 - Continued

Ho (p-BPB) 3. 2Hr° Ho(m-MPB)~.2Hr° Ho(o-BPB~2H20 Ho(DMH) 3 .2H20 in 95% ethane in 95% et ano in 95% et anol in 95% ethanol E(cm-1) e: E(cm-1) e: E(cm-1) e: E(cm-1) e: 15520sh (1.11) 15520sh (0. 98) 15160sh (0.96) 15200sh (1.13) 15310 (cl.3) 15610 (2.49) 15620 (2.26) 15630 (2.20) 15650 (2.64)

18340 (cl.6) 18330wsh (cl. 9) 18340sh (1.69) 18380wsh (c3.2) 18480wsh(c2.6) 18500wsh (c2.5)

18640 (3.40) 18640 (3. 24) 18600 (3.22) 18610 (4.76)

20310 (cl.0) 20300wsh (c0.3) 20310wsh (c3. 2) 20580 (4.45) 20590 (1.75) 20570 (1.61) 20590 (4.05) 20700sh (4.25) 20680sh (1.47) 20650sh (1. 31) 20680sh (3.82)

21140sh (5.43) 21140 (1.80) 21120 (1.61) 21150 ( 4. 20)

21370 (6. 48) 21360 (2.37) 21320 (2.12) 21360 ( 4. 68) 21470 (6.38) 21460sh (2.16) 21430sh (1. 86) 21490sh (4.47)

21690 (41.0) 21690 (29.0) 21670 (28.7) 21690 (25.4) 22170 (105. 5) 22170 ( 77. 2) 22140 (74.7) 22170 (60. 0)

2300wsh (c2.0) 23470 (14.1) 23260wsh (c3.5) 23250wsh (c4 .9) 23580sh (14.7) 23660sh (5. 65) 23580wsh (cS. 3) 23620wsh (c6.3) 23750sh (15.1) 23750 (5. 77) 23740wsh (c6.2) 23810wsh (c6.9) 23870 (15.4) 23920 (5. 78) 23900 (6. 82) 23900 (7.12)

25870 (7.61)

26150 (8.20)

27700 (42.2) 50

Table 3.8

Visible Spectra of the Erbium Chelates

3 3 11 Electronic Er + (aq) 11 Er + (aq) Er(N03)3.6H20 Er(TTB) 3.2H20 Transition calculated exptl. in dimin. H20 in 95% ethanol E(cm- 1) E (cm-1) E(cm-1) e: E (cm-1) £

(0.57) 1500wsh 4 +4 15245 15250 {15020sh (cO. 7) 115/2 F9/2 15340 (2.06) 15310 (2.36)

4 18350 (0.22) 18410 53/2 18462 {1s;so (1.18) 18500 (0. 71) 18480 (1.11)

2 {19010sh (10.6) Hll/2 19256 19150 19160 (3.52) 19120 (29. 2) 19270 (52.1)

4 (0 .93) F7/2 20422 20450 {20410 l 20490 (2.78) 20580 (2 .11)

(0. 41) 21980sh (1.45) 4 22074 {22120 F5/2 22100 22270 (0.93) 22229 (1. 97) 4 F3/2 22422 22500 22680 (0.45) 22620 (1.60)

(2G '4Ft (0.57) 23505 24550 {24630 2H)9/12 24750 (0.77)

4 Gll/2 26496 26400 26460 (6. 94)

4 G9/2 27478 27400 27550 (2.08) 2 KlS/2 27801 27820 (0.41) 2 G7/2 27979 28000 28070 (0.92) 51

Table 3.8 - Continued

Er(p-BPB)3.2H20 Er(m-MPB) 3.2H20 Er(o-MPB)3.2H20 Er(DMH)3.2H20 in 95% ethanol in 95% ethanol in 95% ethanol in 95% ethanol E(cm-1) E E(cm-1) E E(cm-1) E E (cm-1) E r4960sh (I. 11) 15020wsh (0.5) 14940sh (c0.4) 14950wsh (cO .4) 15220sh (2.49) 15080wsh (c0.6) 15330 (3.86) 15280 (2.3) 15300 (1.68) 15300 (1.63)

18070wsh(c2.6) 18230wsh (c0.5) 18340 (3.43) 18320 (1.02) 18380 (0.91) 18390 (1.06) 18430 (3.43) 18420 (0. 95) 18460 (0.81) 18460 (1.05)

18870 (9.43) 18900sh (8 .67) 18870 (8.17) 18910 (6.82) 19060 (21. 2) 19060 (23.2) 19080 (21.0) 19140 (18.2) 19210 (29.2) 19210 (41.0) 19210 (38.0) 19260 (31. 7) f20170wsh(c6.8)J 20470 20460 (9.52) 20450 (2.04) [20470 (2.03) (1. 96-) 20690wsh(cl. 0) 20690 20590 (8.23) (0. 92)

21980sh (1.02) 22020sh (0.98) 21990sh (0.81) 22170 (14.8) 22170 (1. 42) 22170 (1.44) 22180 (1.17)

22550 (1.26) 22580 (1. 35) 22620 (0.86)

24390 (3.43) 24530 (2.06) 24570sh (3.31) 24680sh (2.05)

26000wsh (c28) 26240 (55.6) 26430 (96. 4)

27430 (10.0)

27680wsh (c9 .9) 27872sh (11.2)

27980 (12.4) N

2 22)

92)

·•

(1 (0.31)

(2.54) (2.60) (0. (1.23) (2.73)

thanol

)

95%

in 15110sh

14620 21230 21550 12640 26470 19230

E(cm-

Tm(DMH)~.2H

anol

(3.21) (0.50)

(4.48) (2.59) (2.16) (0.93)

95%

12620 in

14589 21130

15120sh

19190 21520 E(cm-1)

Tm(m-MPBi2H

71) 27)

(1.98)

(3. (3.07) (0.35)

(0.

(2.46)

Chelates

Ethanol

95%

3.9

12630

14600

E(cm-1) 15110 19210 21160 21530

Thulium Tm(TTB)3.2H20

{

the

Table

.3)

(0.86)

(0.89)}

(0.23)

(2.58)

( 4 (

.6H

demin.H

Spectra

12850

14370

E(cm-1) 15170

14640

21550 TmCI

{

Visible

+(aq)

12700 exptl. 14500

E(cm-1)

15100

28000 28090

21350

(aq)

12720

14510

calc. E(cm-1)

15116

21374

28032

3 4

lG 3F

Electronic

Transition

3H 53

The spectra of the lanthanide chelates of 4,4,4-trifluoro-1-(2'-thienyl) l,3-butanedione, and the nitrates of neodymium, holmium, and erbium, are shown in Figures 3.1 to 3.12.

The visible spectrum of each lanthanide is unique, and the chelates with B-diketones are essentially similar for each lanthanide ion. The known hypersensitive transitions of the lanthanides are listed in

Table 3.10. The hypersensitive transitions that are particularly apparent in the lanthanide chelates prepared in this work are:

(a) neodymium:

(b) europium:

(d) erbium:

Because of the particularly large extinction coefficients of the neodymium, holmium and erbium chelates, the spectra of all 15 chelates prepared were obtained. It is observed that there is variation in the intensities of any particular hypersensitive transition, which is dependent upon the R group. The extinction coefficients are greatest for complexes of 4,4,4- trifluoro-l-(2'-thienyl)-1,3-butanedione (R = 2'-thienyl) and decreases in the order of R: 2'-thienyl > 4'-bromophenyl > 3'-methylphenyl >

2'-methylphenyl > tert. butyl. Henrie et ai. 34 give the order of decreasing hypersensitivity for various B-diketone complexes. They list:

Rl = R2 = phenyl > Rl = 2'-thienyl, R2 = CF 3 > Rl = phenyl, R2 = CH 3; Rl R2 C(CH ) > Rl = R2 CH > Rl CF , R2 CH > Rl = R2 = CF . = = 3 3 = 3 = 3 = 3 3 This reflects the ligand basicity when associated with a highly polarising

+3 ion, but not necessarily the pK values, particularly with conjugated a Or aromatic Systems. 45,51,61 Al t h oug h nova 1 ues are ava1·1 a bl e f or t h e

.i:--

V, V,

) )

3 3

I> I>

,c10 ,c10

~ ~

I I

(cm-

E E

' '

15 15

\. \.

L', L',

"=-7-

I I

20 20

(4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedionato) (4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedionato)

Ethanol. Ethanol.

95% 95%

diaquotris diaquotris

in in

I I

of of

25 25

spectrum spectrum

Praseodymium(III) Praseodymium(III)

Visible Visible

3.1. 3.1.

, ,

Figure Figure

~ ~

30 30

O O

5 5

10 10 E E V1

)

---

E(cm-1x10

water.

I \

nitrate

Neodymium

spectrum

Visible

3.2.

Figure

•

3 6

E V,

)

B x

(cm-

I \

8 i

I I ,

(4,4,4-trifluoro-l-(2'-thienyl)-1,3-butanedionato)

Ethanol.

diaquotris

95%

spectrum

Visible Neodyrniurn(III)

3.3.

Figure

Scale

-t-6 30 J-e

Scale u, --.J

}

E(cm-1x10

-thienyl)-l,3-butanedionato)

----s

(4,4,4-trifluoro-1-(2

··•

Ethanol.

diaquotris

of 95%

spectrum

Samarium(III)

Visible

3.4.

Figure

Scale

0-+---~~----r----.----...---..------r-----.-----,------,.------il--~

10+1

Scale

(X) (X)

V, V,

) )

x x

1 1

~ ~

E(cm-

i i

15 15

B B

• •

:=:: :=::

A A

20 20

• • I

i i

I I

A A

I I

111\ 111\

(4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedionato)

Ethanol. Ethanol.

diaquotris diaquotris

95% 95%

of of

I I

25 25

in in

spectrum spectrum

europium(III) europium(III)

Visible Visible

B B

3.5. 3.5.

Scale Scale

Figure Figure

0.4 0.4

0.6 0.6

I I

+0.2 +0.2

j j

30 30

0 0

3 3

1 1

4+0.8 4+0.8

2-+ 2-+

A A Scale Scale

V, V,

'° '°

) )

3 3

><10 ><10

1 1

E(cm-

15 15

20 20

Ethanol. Ethanol.

diaquotris(4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedionato)

of of

95% 95%

in in

25 25

spectrum spectrum

terbium(III) terbium(III)

Visible Visible

3.6. 3.6.

Figure Figure

30 30

1 1

2 2

3 3

5 5

4 4

OL_~~~~~ OL_~~~~~ £ £ 0

)

x10

cm-

Ethanol.

diquotris(4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedionato)

95%

spectrum

dysprosiurn(III)

Visible

3.7.

Figure

Q\ Q\

......

> >

r'° r'°

15 15

( (

) )

x10

~ ~

(cm-

E E

r-60 r-60

I I

L L

I I

20 20

Water. Water.

\ \

in in

I I

Nitrate Nitrate

1 1

I I

Holmium Holmium

\ \

0f 0f

L L

I I

25 25

» »

spectrum spectrum

1 1

Visible Visible

I I

\ \

3.8. 3.8.

I I

Figure Figure

I I

30 30

1 1

2 2

3 3

4 4

0 0 E E

N N

°' °'

) )

x10

E(cm-

15 15

l\ l\

'---B '---B

l l

_r-..,.,.___ _r-..,.,.___

I I

...-

. .

20 20

\ \

(4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedionato) (4,4,4-trifluoro-1-(2'-thienyl)-l,3-butanedionato)

.,,.'"'---. .,,.'"'---.

I I

\I\Y\ \I\Y\

I I

J J

111 111

U U

Ethanol. Ethanol.

diaquotris diaquotris

B B

of of

95% 95%

__ __

in in

" "

\ \

A A

I I

spectrum spectrum

25 25

Visible Visible

Holmium(l11) Holmium(l11)

3.9. 3.9.

B B

Figure Figure

2 2

3 3

Scale Scale

5 5

1 1

I I I I

I I

~ ~

+-4 +-4

30 30

0 0

80i 80i

20 20

60 60

40 40 ScaleA~ ScaleA~

°' °'

w w

) )

3 3

cm-1x10 cm-1x10

E ( ( E

15 15

1152 1152

water. water.

in in

20 20

nitrate nitrate

erbium erbium

of of

spectrum spectrum

25 25

694 694

Visible Visible

I I

3.10. 3.10.

Figure Figure

30 30

0 0

2.0 2.0

1.0 1.0

1.5 1.5 0.5 0.5 £ £

~ ~

(1\ (1\

> >

, ,

) )

j j

x10

, ,

cm-

E ( ( E

l l

B B

15 15

, , ,

-thienyl)-1,3-butanedionato) -thienyl)-1,3-butanedionato)

~ ~

B B

t t

, ,

20 20

(4,4,4-trifluoro-1-(2

diaquotris diaquotris

Ethanol. Ethanol.

of of

~ ~

95% 95%

B B

in in

A A

spectrum spectrum

25 25

erbium(l11) erbium(l11)

Visible Visible

3.11. 3.11.

B B

Figure Figure

, , ,

Scale Scale

2 2

3 3

·1 ·1

I I

30 30

A A

0 0

30 30

20 20

40 40

10 10

E E Scale Scale

VI VI

°' °'

) )

x10

E(cm-

15 15

20 20

(4,4,4-trifluoro-l,3-butanedionato) (4,4,4-trifluoro-l,3-butanedionato)

Ethanol. Ethanol.

diaquotris diaquotris

of of

95% 95%

25 25

in in

spectrum spectrum

Visible Visible Thulium(III) Thulium(III)

3.12. 3.12.

Figure Figure

30 30

7 7

6 6

5 5

8 8

0 0 1 1

4 4

3 3

2 2 E E 66

ligand basicity of the 8-diketones with substituted phenyl rings, it may be speculated that the order of increasing basicity (when coordinated to a highly polarising +3 ion) is reflected by the increasing intensities of the hypersensitive transitions. For 8-diketones that are not coordinated the basicity would be expected to increase for R in the order: C(CH3) 3 < 2'-thienyl < 2'-methylphenyl < 3'-methylphenyl < 4'-bromophenyl. The difference (particularly with the aromatic compounds) is presumably due to the effects of coordination to the +3 ion. The intensity enhancement in comparison to the nitrates can be observed in

Figures 3,2, 3.3, 3.8-3.11.

As each lanthanide ion has a unique absorption spectrum they will be discussed individually.

Praseodymium(III): the transitions 3H,. + 1D and 3H + 3p ~ 2' Ii 2 (Table 3.1) have previously been observed to show hypersensitive behaviour (Table 3.11). A change in extinction coefficient or splitting of peaks is expected. No intensity enhancement is observed for the complexes in comparison with the nitrate but the transition to 1D is 2 split into four maxima (two are shoulders).

Neodymium: 4f3 , has three hypersensitive transitions, reasonably close in energy, that are in the range measured (Table 3.11). For the

3 tiI 9 ; 2 + lic 712 , K13 / 2 intensity enhancement of the chelates was approxi mately seven times the extinction coefficient of the nitrate. The transition to tiG 7 / 2 was enhanced only twice. Significant splitting of the transitions occurred (Figure 3.3).

5 -1 Samarium(III): 4f, has a hypersensitive transition at 26600 cm

Due to ligand absorption the transition is only observed for the 1,1,1- trifluoro-5,5-dimethyl-2,4-hexanedione chelate. The intensity of the absorptions for all transitions are somewhat misleading as all maxima 67

Table 3 .10 Hypersensitive Transitions of the Lanthanide Ions

Ion ( +3) Electronic Transition

Pr 17.0

22.5

Nd 17.3

+ 19.2

Sm 6.2

26.6

Eu 21.5

Dy 23.4

Ho 22.2

28.0

Er 4I + 2H 19.2 15/2 11/2 4 + 4 26.5 115/2 Gll/2

Tm 12.6 68

occur as shoulders or small peaks on the ligand absorption curve (Figure

3.4).

6 7 Europium(III): 4f , has the ground state F0 and the next state

7 F1 is appreciably occupied also. Transitions from both occur (Table 3.4).

7 5 The transition F0 + D2 is hypersensitive and significant intensity enhancement occurs (50 times). The trend observed for the variation of extinction coefficient with the ligand was followed (Table 3.4).

Terbium(III): 4f8 , has extremely simple visible spectra for all complexes measured. There are no hypersensitive transitions.

Dysprosium(III): 4f,9 has a hypersensitive transition at

-1 23400 cm A maximum occurs but no hypersensitivity of the transition was found. The increased extinction coefficients are due to the 'tail' of the ligand absorption.

Holmium(III): 4f10, contains two hypersensitive transitions in the visible range. Only one is observed for all complexes except those of 1,l,1-trifluoro-5,5-dimethyl-2,4-hexanedione. transition enhancement in the extinction coefficient is approximately 20 times, and splitting of the absorption occurs. is enhanced 17 times but no splitting occurs.

Erbium(III): 4f11, also has two hypersensitive transitions, one of which is obscured by the ligand absorptions for all complexes except

those of 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione. The

4 2 1 15 ; 2 + H11 ; 2 transition is enhanced by approximately ten times,

4 4 depending upon the ligand. The 1 15 / 2 + G11 / 2 transition is enhanced 15 times.

The orange colour of the chelates of cerium(III) is due to the

tail of an intense charge-transfer in the ultraviolet. 69

III. Experimental

Absorption spectra were measured on a Cary Model 17 spectrophotometer with stoppered quartz cells, over the range 13000 to 30000 cm -1 •

The concentrations of solutions used were in the range 0.01 to 0.06M, depending upon the predicted extinction coefficient of the absorptions.

The solutions were prepared in 5 mL volumetric flasks, with 95% ethanol for the complexes, and demineralized water for the nitrates, as the solvent. The solutions were filtered prior to the recording of

the spectra. Extinction coefficients were calculated using the Beer

Lambert law. PART FOUR

MAGNETIC PROPERTIES OF THE

LANTHANIDE CHELATES

I. Background

The 4f electrons of the lanthanide ions are very effectively shielded from the influence of external forces by the overlying Ss2 and

Sp6 shells, which means that the lanthanide ions are relatively unaffected by the chemical environment. As a result, the states arising from the various 4fn configurations are practically invariant for a given ion in all its compounds.

A useful approximation to the states of the 4fn configurations is given by the Russell-Saunders coupling scheme. The spin-orbit coupling -1 constants, of the order of 1000 cm , are quite large so that, with only two exceptions, the lanthanide ions in a compound act in the same way as the free ion. Except for the ions sm3+ (4f5) and Eu3+ (4f6) the lanthanide ions have ground states with a single well-defined value of the total angular momentum, J, with the next J state at energies many times kT above, hence virtually unpopulated. The magnetic moments of these ions have been calculated by Hund29 , 37 for the free ion with the use of

Equation 4. 1.

µeff = g [J(J+l)]~ Equation 4.1

Equation 4.1, however, fails to account for the magnetic behaviour of the ions Sm3+ and Eu3+, and the non zero values of the Weiss constants (8) 3+ for all the ions except Gd . The experimentally determined magnetic 3+ 3+ moments of Sm and Eu vary considerably with temperature, for these two

70 71

ions the first excited J state is sufficiently close in energy to the ground state - and in the case of Eu3+, even the second and third excited states - to be appreciably populated at room temperature. Since these excited states have higher J values than the ground state, the actual magnetic moments are higher than those calculated by means of Equation 4.1 and the value of J for the ground state.

Equation 4.1 provides no mechanism for the variation of magnetic moment with temperature which is apparent due to the finite value of the

Weiss constant. A refinement of equation 4.1, proposed by Van Vleck and 86 Frank, taking into account the second-order Zeeman effect and any population of higher states; it gives a much better approximation to the experimental results, particularly for samarium(III) and europium(III).

It also predicts that the moment will be temperature dependent, i.e., with nonzero Weiss constants, although less than is actually found experimentally.

Spin-orbit coupling in the lanthanide ions is so large that the ligand field splitting is usually negligible compared with the separation between adjacent states, but each state may be split by an amount of

-1 ~ 100 cm • The splitting patterns for f configurations are complicated by: (a) interaction of the f orbitals and the ligand field, and (b) the synunetry of eight coordination around the metal ion.

Equation 4.1 contains no quantity that varies with the chemical environment of the ion, hence it predicts that the magnetic properties of the lanthanides should be independent of the compound in which they are studied.

Various workers have determined the magnetic moments of lanthanide 7 30 80 compounds over a variable temperature range. ' ' The values obtained. are all fairly close to those predicted by Van Vleck and Frank;86 and variation was found to be minimal between different compounds. All the 72

compounds, except those of samarium and europium, obey the Curie-Weiss law.

II. Results and Discussion

The magnetic susceptibilities of thirty lanthanide chelates of fluorinated 8-diketones have been determined over the temperature range of 99 to 304K. All the complexes, except those of samarium(III) and europium(III), obey the Curie-Weiss law (Equation 4.2), where C is the ' Curie constant and XM the corrected molar magnetic susceptibility.

C = Equation 4.2 T + 8

It should be noted that in this work the values of the Weiss constant,

8, although listed as positive, are the negative of the intercept on the ' Taxis of the plot of 1/xM versus T; i.e., the intercept occurs below zero degrees Kelvin. The values of µeff at 298K are calculated by the

Curie law, i.e. by use of equation 4.3, while those of µeff * are calculated 70 by the use of Equation 4.4.

= 2.828 (X~ T)~ Equation 4.3

* µeff 2.828 (X~ (T + 8))~ Equation 4.4

The susceptibilities of the ten chelates of samarium(III) and

europium(III) were found not to obey the Curie-Weiss law (Equation 4.2).

I I The values obtained for XM, 1/XM, and µeff are given in Tables 4.1 to

4.4. The magnetic moments are found to vary considerably with temperature. 73

Table 4.1

Magnetic Data for the Samarium Chelates of 6-Diketones with R = 2'-Thienyl, p-Bromophenyl, and m-Methylphenyl.

Sm(TTB) 3 .2H20 Sm(p-BPB) 3 .2H20 Sm(m-MPB) 3 .2H20

1/X I Temp. 106xM' M µ eff 106x.M I 1/xM' µeff 1cf>xM' 1/XM µeff

89.1 1708 585 1.10

98.9 1273 785 1.00 1602 624 1.13 1074 831 0.93

113. 2 1230 813 1.05 1517 659 1.17 1105 905 1.00

127.6 1213 824 1.11 1453 688 1.22 1074 931 1.05

142.0 1187 842 1.16 1411 709 1.27 982 1019 1.06

156.5 1170 855 1.21 1379 725 1.31 1028 973 1.14

171.3 1161 861 1.26 1283 779 1.33 982 1019 1.16

186.1 1135 881 1.30 1230 813 1.35 982 1019 1.21

200.8 1084 923 1.32 1187 842 1.38 966 1035 1.25

215.6 1092 916 1.37 1177 850 1.42 1012 988 1.33

230.3 1084 923 1.41 1123 890 1.44 982 1019 1.35

244.9 1118 894 1.48 1145 874 1.50 966 1035 1.38

259.9 1084 923 1.50 1166 858 1.56 1028 973 1.47

275.0 1075 930 1.54 1155 866 1.59 966 1035 1.46

289.8 1101 908 1.60 1177 850 1.65 966 1035 1.50

304.4 1177 850 1.69 966 1035 1.54

318.2 982 1019 1.59

333.2 1028 973 1.66

-1 N.B. Units T(K), 1/xM ( cgs ), 74

Table 4.2

Magnetic Data for the Samarium Chelates of S-Oiketones with R = o-Methyl, and Tert. B~tyl.

S.m(o-MPB)_:;,21-/2 0 Sm(DMH) 3. 2H20 Temp 6 6 10 Xt.1 1/'Xt.f µ eff 10 Xt.t 11xM µeff (K) (cgs) (cgs-1) (B.M) (cgs) (cgs-1) (B.M)

98.9 1517 659 1.10 1403 713 1.05

113.2 1455 687 1.15 1324 755 1.09

127.6 1393 718 1.19 1324 755 1.16

142.0 1393 718 1.26 1199 834 1.17

156.5 1405 712 1.33 1177 850 1.21

171.3 1368 731 1.37 1109 902 1.23

186.1 1330 752 1.41 1120 893 1.29

200.8 1318 759 1.45 1075 930 1.31

215.6 1293 773 1.49 1052 950 1.35

230.3 1268 789 1.53 1052 950 1.39

244.9 1255 797 1.57 1052 950 1.44

259.9 1255 797 1.62 1063 940 1.49

275.0 1268 789 1.67 1041 961 1.51

289.8 1255 797 1. 71 1041 961 1.55

304.4 1280 781 1. 77 1086 921 1.63

318.2 1343 745 1.85 1063 940 1.65

333.2 1097 911 1. 71 75

Table 4.3

Ma~etic Data for the Europium Chelates of 6-Diketones with R = 2'-Thienyl, p-Bromophenyl, and m-Methylphenyl.

Eu(TTB)3.2H20 Eu(p-BPB) 3 .2H20 Eu(m-BPB) 3 .2H20 Temp 106X,1 1/Xt.i 106x I 11xM lO~X.', 1/Xt.i .-t µeff :,1 µeff .1 µe!ff

89.0 5879 170 2.05

98.9 5908 169 2.16 5866 170 2.15 6101 164 2.20

113.2 5831 172 2.29 5734 174 2.28 5987 167 2.33

127.6 5715 175 2.41 5641 177 2.40 6025 166 2.48

142.0 5663 177 2.53 5575 179 2.52 5924 169 2.59

156.5 5586 179 2.64 5482 182 2.62 5924 169 2. 72

171.3 5483 182 2.74 5349 187 2. 71 5784 173 2.82

186.1 5328 188 2.82 5257 190 2.80 5633 178 2.90

200.8 5238 191 2.90 5151 194 2.88 5519 181 2.98

215.6 5070 197 2.96 5045 198 2.95 5405 185 3.05

230.3 4980 201 3.03 4872 205 3.00 5228 191 3.10

244.9 4748 211 3.05 4806 208 3.07 5063 198 3.15

259.9 4710 212 3.13 4714 212 3.13 5051 198 3.24

275.0 4555 220 3.17 4608 217 3.18 4937 203 3.30

289.8 4503 222 3.23 4502 222 3.23 4823 207 3.35

304.4 4413 227 3.28 4422 226 3.28 4684 214 3.38

318.2 4271 234 3.30 4303 232 3.31

333.2 4207 238 3.35 4197 238 3.34

348.2 4181 239 3.41

-1 N.B. Units T(K). 106 I (cgs), XM 1/xM (cgs ) ' \.leff(B.M) 76

Table 4.4

Magnetic Data for the Europium Chelates of S-Diketones with R = o-Methyl, and Tert Butyl.

Eu(p-BPB) 3.2H20 Eu(DMH) 3.2H2o Temp 106x' 6 M 1/x' M )Jeff 10 Xt.'.t 11xM )Jeff (K) (cgs) (cgs-1) (B.M) (cgs) (cgs-1) (B .M)

98.9 7700 130 2.47 6343 158 2.24

127.6 7479 134 2.76 5985 167 2.47

156.5 7179 139 3.00 5817 172 2.70

186.1 6808 147 3.18 5570 180 2.88

215.6 6447 155 3.33 5290 189 3.02

244.9 6026 166 3.44 4999 200 3 .13

275.0 5835 171 3.58 4753 210 3.23

304.4 5594 179 3.69 4697 213 3.38 77

For the samarium chelate of 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedione µeff varied from 1.00 at 99K to 1.60 at 288K. Plots of µeff versus Tare given for the samarium chelates in Figures 4.1 to 4.5. Due to the low magnetic moment of the samarium ions, a significant error becomes inherent from the weighings used in the Guoy method. Error bars have been included in the plots for this reason, but are only calculated for the errors involved in the weighings. Although there are some anomalies, the plots of µeff against Tare approximately linear; this agrees well with the calculated variation of µeff with T determined by I Van Vleck (Figure 4.6). The plots of 1/xM against Tare not linear and I in fact the value of 1/xM begins to decrease at temperatures in excess of

250K, as shown in Figures 4.7 to 4.9.

Although the lowest temperature obtainable was 90K, a marked decrease in the magnetic moment of the europium chelates was observed.

For the europium chelate of 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedione it varies from 2.16 at 99K to 3.41 B.M. at 348K. The plots of µeff against T for the complexes (Figures 4.10 to 4.14) show a distinct curve with each extreme becoming linear. As for the samarium chelates this is as predicted by Van Vleck, as shown in Figure 4.6. Included for comparison are the plots of the samarium(!!!) and europium(III) chelates of 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedione. Although the experimental results are below the calculated curves, they are closer than the examp 1 es g i ven b y Figgis. · an d Lewis, · 29 b ot h in. magnetic. moment and s h ape.

Error bars were again calculated but due to the larger magnetic suscepti bility of the europium chelates they were too small to be shown. The

I plots of 1/XM versus T for the europium chelates were curves as shown in

Figures 4.15 to 4.17...... 00

T(K)

300

200

diaquotris(4,4,4-trifluoro-1-(2'-thienyl)-

for

against

1,3-butanedionato)samarium(III)

100

µeff

Plot

4.1.

Figure

1.5

1.0

~eff

(BM)

......

'° '°

T(K) T(K)

300 300

200 200

diaquotris(4,4,4-trifluoro-1-(4'-bromophenyl)-

for for

T T

1,3-butanedionato)samarium(III) 1,3-butanedionato)samarium(III)

against against

100 100

µeff µeff

of of

Plot Plot

4.2. 4.2.

Figure Figure

1.0 1.0

1.5 1.5

~eff ~eff (BM) (BM) 00

T(K)

300

200

diaquotris(4,4,4-trifluoro-1-(3'-methylphenyl)-

1,3-butanedionato)samarium(III)

for

against

100

µeff

Plot

4.3.

Figure

1.0

1.5

~eff

(BM) 00

I-'

T(K)

300

200

diaquotris(4,4,4-trifluoro-1-(2'-methylphenyl)-

for

1,3-butanedionato)samarium(III)

against

100

µeff

Plot

4.4.

Figure

1.0

µeff

(BM) N

T(I<)

300

200

diaquotris(l,1,1-trifluoro-S,S-dimethyl-

for

2,4-hexanedionato)samarium(III)

against

100

µeff

Plot

4.5.

Figure

1.0-,

1.5

Ueff BM)

( 83

µeff lBM) - .... --- .... -- -.... -- .,,,. ... - .,,,. - 3 .,,,. .,,,. ,,, .,,,. ., / Eu ( TTBJ3. 2H20 / / / / / / / / 2 -.... .,,- - ... .. --- .,,------_... --Sm(TTB)T2H o ...... - 2 1 .,. --

100 200 300 T(K)

Figure 4. 6. Calculated µ for the Configurations fs and f6 as a Function of T. Experimental Results for the Samarium and Europium Chelates of 4,4,4-trifluoro-1-(2'-thienyl)- 1,3-butanedione are Included for Comparison (Dashed Lines). 1000 1

X'M

(cg s-1)

00 ~

sooL----r------:!::-----~;--~~--:? 0 100 200 300 T(K)

Figure 4.7. Plot of 1/xM against T for diaquotris (4,4,4-trifluoro-1-(2'-thienyl) l,3-butanedionato) samarium(III).

V, V,

00 00

o o

T(K} T(K}

.2H

-methylphenyl)

300 300

4,4,4-trifluoro-l

Sm(p-BPBl:3 Sm(p-BPBl:3

of of

Chelates Chelates

4,4,4-trifluoro-1-(3

and and

l,3-butanedione l,3-butanedione

200 200

Samarium Samarium

the the

for for

T T

against against

0 0

.2H

1/xM 1/xM

100 100

of of

(4'-bromophenyl)-l,3-butanedione (4'-bromophenyl)-l,3-butanedione

Plots Plots

Sm(m-MPB)

4.8. 4.8.

Figure Figure

0 0

500 500

1000 1000

-1, -1,

s s

1 1

x~ x~ (cg (cg 1000

1 x/ Sm(DMH)3. 2H20 M (cgs-1)

· I Sm~-MPBl3• 2H2 ~o 00a,

sonL------,------~------=-r=--~~----;:, 0 100 200 300 T(K)

Figure 4.9. Plot of 1/xM against T for the Samarium Chelates of 4,4,4-trifluoro-1- (2'-methylphenyl)-l,3-butanedione and 1,1,1-trifluoro-5,5-dimethyl-2,4-he:xanedione. 4

Pett (BMl

00 ......

2~------~ 0 100 200 300 T(K)

Figure 4.10. Plot of µeff against T for diaquotris(4,4,4-trifluoro-1-(2'-thienyl)-l,3- butanedionato)europiurn(III) 4

µeff

( BM)

00 00

2+------.------~ 0 100 200 300 T(K)

Figure 4.11. Plot of µeff against T for diaquotris(4,4,4-trifluoro-1-(4'-bromophenyl) l,3-butanedionato)europium(III).

00 00

\0 \0

T(K) T(K)

300 300

200 200

diaquotris(4,4,4-trifluoro-1-(3'-methylphenyl)

for for

T T

l,3-butanedionato)europium(III). l,3-butanedionato)europium(III).

against against

100 100

µeff µeff

of of

Plot Plot

4.12. 4.12.

0 0

Figure Figure

3 3

2 2

4 4

µeff µeff

BM) BM) ( (

1.0 1.0

0 0

T(K) T(K)

D D

300 300

D D

□ □

200 200

□ □

diaquotris(4,4,4-trifluoro-l-(2'-methylphenyl)-

□ □

for for

□ □

T T

1,3-butanedionato)europium(III). 1,3-butanedionato)europium(III).

□ □

against against

100 100

µeff µeff

of of

Plot Plot

4.13. 4.13.

0 0

Figure Figure

2+------.~------T"------~ 2+------.~------T"------~

3 3

4 4

Pett Pett (BMJ (BMJ

I-' I-'

'° '°

T(K) T(K)

300 300

200 200

~ ~

europium(III). europium(III).

diaquotris(l,1,1-trifluoro-S,5-dimethyl-2,4-hexanedionato) diaquotris(l,1,1-trifluoro-S,5-dimethyl-2,4-hexanedionato)

for for

T T

against against

100 100

µeff µeff

of of

Plot Plot

4.14. 4.14.

0 0

Figure Figure

4 4

3 3

2-1------~------r------~ 2-1------~------r------~

µeff µeff {BM) {BM)

N N

1.0 1.0

T(K) T(K)

0 0

300 300

.2H

4,4,4-trifluoro-1-

of of

Eu(o-MPB)

Chelates Chelates

4,4,4-trifluoro-1-(2'-methylphenyl)-

Europium Europium

200 200

and and

1,3-butanedione. 1,3-butanedione.

the the

for for

T T

2H20 2H20

• •

against against

(TTB)

1/XM 1/XM

Eu Eu

100 100

of of

(2'-thienyl)-1,3-butanedione (2'-thienyl)-1,3-butanedione

Plot Plot

4.1~. 4.1~.

Figure Figure

0 0

--t------r------.------r-----~ --t------r------.------r-----~

200 200

150 150

M M

s-1) s-1)

1 1

X' X' (cg (cg

w w

'° '°

T(K) T(K)

300 300

europium(III). europium(III).

200 200

diaquotris(4,4,4-trifluoro-1-

for for

T T

against against

1/xM 1/xM

100 100

of of

(4'-bromophenyl)-l,3-butanedionato) (4'-bromophenyl)-l,3-butanedionato)

Plot Plot

4.16. 4.16.

Figure Figure

150-' 150-'

200-1 200-1

_,l _,l

1 1

x~ x~

cgs cgs ( (

.p. .p.

1.0 1.0

T(K) T(K)

0 0

2 300 300

1,1,1-trifluoro-

4,4,4-trifluoro-

,2H

and and of of

DMH)

o o

( (

Chelates Chelates

Eu Eu

. .

PB)

Europium Europium

200 200

(m-M (m-M

the the

Eu Eu

for for

T T

against against

5,5-dimethyl-2,4-hexanedione. 5,5-dimethyl-2,4-hexanedione.

1/XM 1/XM

100 100

of of

1-(3'-methylphenyl)-methylphenyl)-l,3-butanedione 1-(3'-methylphenyl)-methylphenyl)-l,3-butanedione

Plot Plot

4.17. 4.17.

Figure Figure

150~0------;;;------=:------..------==--

200 200

250 250

) )

M M

1 1

X' X' (cg (cg 95

The results obtained for the complexes that obeyed the Curie-Weiss

law are summarised in Tables 4.5 to 4.9. The values of the Weiss

constant, 0, except for the cerium complex are relatively small. The

complexes all gave excellent correlation with a straight line, as shown

for the complexes containing 4,4,4-trifluoro-l-(2'-thienyl)-l,3-butane-

I I dione in Figures 4.18 to 4.20. The values for XM' 1/xM, and µeff for all complexes that were found to obey the Curie-Weiss law are listed in

Appendix A. The values obtained for µeff * were calculated at 298K by means of the Curie-Weiss law; it should be noted that this may give a

significantly different value from µeff (Curie law) if 0 is large. The values obtained in this work are within the experimental range given by

Figgis and Lewis29 for lanthanides, as listed in Tables 4.5 to 4.9.

The high magnetic moment of the lanthanides gadolinium to terbium may result in contact between the Gouy tube and the interior of the

cryostat during the weighings in the magnetic field. If this occurs for

a particular measurement, it reduces the pull, and hence gives an increased

I 1/XM (Fig. 4.20).

III. Experimental

The magnetic data were collected over a temperature range of 9O-35OK

by means of the Gouy method. A 10 cm glass tube, calibrated for its

diamagnetic corrections at various temperatures and magnetic field

strengths, was packed as uniformly as possible with the sample. The

measurements were made on a Newport variable-temperature Cbuy balance,

calibrated by a platinum resistance thermometer and indirect methods with

known compounds. Liquid nitrogen was used as coolant. Diamagnetic 69 corrections for the ligands were calculated from Pascal's constants. 96

Table 4.5

Magnetic Data for Cerium, Praseodymium and Neodymium Chelates

µeff * e (B.M) (OC)

2 Cerium(III): F5/2 Calculated values: Hund37 2.54

Van Vleck85 2.56 Experimental range 29 2.25-2.45 17-210

Ce(TTB)3.2H20 2.82 104

Ce(m-MPB) 3.2H20 2.21 45

3H Praseodymium(III): 4 Calculated values: Hund 37 3.58 85 Van Vleck 3.62

Experimental range29 3.4-3.9 22-63

J:>r(TTB) 3.2H20 3.57 39

Pr(o-MPB) 3.2H20 3.68 62

Neodymiurn(III): 4 19/2 Calculated values: Hund37 3.62

Van Vleck 85 3.68 29 Experimental range 3.1-3.5 18-57

Nd(TTB) 3. 211:P 3.62 41 Nd(DMH) 3.2H20 3.91 64

* Calculated in this work by eqn. 4.4. 97

Table 4.6

Magnetic Data for the non-Curie-Weiss Dependent Samarium and Europium Chelates.

Samarium(III): 6H2} Calculated by Hund37 0.84

Van Vleck85 I\, 1.6

.Eicperimental range29 1.4-1.7

Sm(TTB) 3.2H20 1.63 Sm(p-BPB)3.2H20 1.67

Sm(m-MPB) 3.2H20 1.52

Sm(o-MPB) 3.2H20 1.75 Sm(DMH)3.2H20 1.62

Europium(III):

Calculated by Hund 37 0

Van Vleck 85 'v 3 .5

Experimental range 29 'v 3.4

Eu(TTB) 3 .2H20 3.22

Eu(p-BPB) 3.2H20

Eu(m-MPB) 3.2H20 3.27

Eu(o-MPB) 3.2H20 3.37

Eu(CMH) 3.2H 20 3.37

* Calculated by use of eqn. 4.3. 98

Table 4.7

Magnetic Data for Gadolinium, Terbium and Dysprosium Chelates

µefl 8 (B.M) (°C)

Gadolinium(III): 8s712 Calculat-d values: Hund 37 7.94 85 Van Vleck 7.94

Experimental range 29 'v7. 9 '\, 0

Gd(TTB) 3 .2H20 8.05 2

Gd(m-MPB) 3.2H20 7.80 0

Terbium(III):

Calculated values: Hund37 9. 72

Van Vleck 85 9.7 29 Experimental range 'v9 .5 "- 10

Tb(TTB) 3.2H 20 9.82 8

Tb(o-MPB) 2.2H20 9.73 10

6 Dysprosium(III): H15'/2 Calculated values: Hund 10.63

Van Vl~ck 10.6

Experimental range 29 9.8-10.5 5-21

Dy(TTB) 3.2H20 10.69 4

Dy(p-BPB) 3.2H20 10. 40 13 99

Table 4.8

. Magnetic Data for Holmium, Erbium and

Thulium Chelates

µeff * e (B.M) (OC)

Holmium(III): SI 8 Calculated values: Hund 37 10.60

Van Vleck85 10.6

Experimental Range 29 'vl0.4 NlO

Ho(ITB)3.2H20 10.36 5

Ho(o-MPB)3.2H20 10.25 7

Erbium(III): 4 115/2 Calculated values: Hund37 9.57

Van Vleck85 9.4

Experimental range29 9.2-10.1 5-28

Er(ITB) 3.2H20 9.57 11

Er(DMH) 3.2H20 9.21 0

Thulium(III): 3H 6 Calculated values: Hund37 7.63

Van Vleck85 7.6

Experimental range29 "'7.1 6-42

Tm(ITB) 3.2tt2o 7.38 9

Tm(m-MPB) 3.2H 20 7.63 18 100

Table 4.9

· Magnetic Data for Ytterbium Chelates

e (B.M) (OC)

Ytterbium(III):

Calculated values: Hund37 4.50

Van Vleck85 4.5

Experimental range 29 3.8-4.9 64-104

Yb(TTB) 3.2H20 4.50 29

Yb(p-BPB) 3.2H20 4.89 46 101

1/x'M 500

400

300

200

100 •

T(K) 0 100 200 300 400

200

100

Pr(TTB) 3.2H20

0 100 200 300 400

200

100 Nd(TTB) 3.2H20

0 100 200 300 400 Figure 4 .18. Plots of 1/X' against T for the Cerium, M Praseodymium and Neodymium Chelates of 4,4,4-trifluoro-1-(2'-thienyl)-1 3-butanedione. 102

1/x'M so

10 Gd(TTB) 3.2tt2o

T(K) 0 100 200 300 400 so

20 Tb(TTB) 3.2tt2o 10

0 100 200 300 400 so

10· Dy(TTB) 3 .2H20

0 100 200' 300 400

Figure 4.19. Plots of 1/xM against T for the Gadolinium, Terbium, and Dysprosium Chelates of 4,4,4-trifluoro-1- (2'-thienyl)-1,3-butanedione. 103

1/x' M

10 Ho(TTB) 3.2H2O 5

T(K) 0 100 200 300 400

15 Er(TTB) .2H 0 10 3 2

0 100 200 300 400

20 Tm(TTB) 3 .2H20 10

0 100 200 300 400

Figure 4.20. Plots of 1/XM against T for the Holmium, Erbium, and Thulium Chelates of 4,4,4-trifluoro- 1-(2'-thienyl)-1,3-butanedione. 104

I The line of best fit for the plots of 1/XM versus T for the complexes that displayed a Curie-Weiss dependence was calculated by the method of least squares. PART FIVE

MASS SPECTRA OF THE

LANTHANIDE CHELA.TES

I. Background

In 1966 MacDonald and Shannon 58 reported the mass spectra of a variety of metal acetylacetonates; included in the study was the spectrum

of tris(2,4-pentanedionato)lanthanum(III), the first reported mass

spectrum of a lanthanide chelate. It was included as lanthanum is

known to form only the tervalent ion, and was compared with the mass

spectra of complexes of metals that were known to display variable valency.

The changes of valency were found to be important in the fragmentation of

many of the chelates studied. Odd-electron ions could be changed to

even-electron ions and vice versa, by change of valency of the metal atom

in the ions. So with nearly all the complexes studied peaks due to the

loss of even-electron neutral fragments from the molecular ion were small

in comparison with those due to the loss of odd-electron neutral fragments.

Clobes et az. 16 in 1971 published results for various fluorinated 8-diketone complexes of aluminium(III), chromium(III), iron(III), and

cobalt(III). They found that in the fragmentation of the 8-diketones

there was competition between the different radical substituents:7 In

l,l,1-trifluoro-2,4-pentanedione either a CF 3 or a CH 3 radical may be lost. By the quasi-equilibrium theory, the process with the largest rate constant

is the one with the lowest appearance potential for decomposition from a

given ion by similar modes. Thus, for the competing reactions of CF 3 versus R, the enthalpy change for the total reaction determines the

relative intensities of the daughter ions if further decomposition is

105 106

-C F.2

\\ �a /F F +c-9" f\\\ / � MetL /C-H E-<--Metl YCH "'- + "o-c o-c�Rot. "

"'R R

-HF

[MetLRt

Figure 5.1. Mechanism of R Group Migration to the Metal 107

minimal. The loss of R becomes predominant as the radical stability of

R increases. H~wever, CF 3 is lost to a greater degree than would be expected by radical stability alone, due to lower ionisation potential of the less fluorinated species relative to the ionisation potential of the more highly fluorinated species.

In the mass spectrum of tris(4,4,4-trifluoro-l-(2'-thienyl)-l,3- butanedionato)iron(III) most of the fragmentation was as predicted by

MacDonald and Shannon, and in addition, thienyl migration to the metal was observed. Phenyl migrations have been observed before, but such a migration has not been observed with chelates of the lanthanides, 54 ' 60 t except when R =Bu. Such migrations of the R group from the ion [FeL2 ]+ to form [FeLR] + was supposed to proceed by loss of the neutral fragments

CF2 , HF, and c 3o2 • Elimination of HF was only observed for ions that already had a fluorine attached to the metal, so it appeared that such a fluorine was the source in HF. The hydrogen in the HF was found to come from they position of the ligand, so the mechanism given in Figure 5.1 was postulated. Also observed in the case of the iron(III) chelate was the loss of CO from the ion [FeL2-cF3]~ The mechanism (Fig. 5.2) does not dictate whether the loss is two rapid elementary processes, the loss of O then CO, or the loss of a molecule of co2. If the metal is unable to undergo a valence change, then after the . 16. 76 initial loss of one odd-electron,neutral fragments are not easily lost. · 75, 76 This allows the loss of even-electron fragments. Reichert et al. ·

found that there was loss of CF2 and CF 3COCHCO for several fluorinated B diketone chelates of the d-transition metals. 54 Lacey and Shannon have reviewed the mass spectra of the metal

chelates of 6-diketones and their dependence on the ability or lack of

ability of the metal ions to change valence. 108

R / L-Met-o-c ) II O==C!..._ C "-H

+ L-Met-C=C L-Met ~o I I ~<-- H R H-C~ J c+II ~ o "'R + Fig. 5. 2. Mechanism of co2 Loss from the [MetL2-cF3] Ion.

Das and Livingstone24 studied samarium(III), europium(III), sadolinium(III), and terbium(III) chelates of 4,4,4-trifluoro-1-(2'- thienyl)-1,3-butanedione in 1975. In 1976 Livingstone and Zimmermann56 studied the lanthanide chelates of three fluorinated 6-diketones p-methyl, p-methoxy, and unsubstituted phenyl rings as the R groups.

They found that the mass spectra were essentially similar for all of

the lanthanides. Fluorine migration was found to occur with the con-

comitant loss of CF2. Valency change from 3 to 2 was found to occur for chelates containing samarium, europium, or ytterbium. · Complexes of

cerium(III) and thulium(III) were not prepared. These valence changes 110

are within the known chemistry of the lanthanides.

More recently Khomenko et az.47- 50 , 83 have continued work on lanthanide chelates of B-diketones. In 1979 they reported the mass spectrum of the tris 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedionato chelate of europium49 and the neodymium chelate in 1981.50 They have also studied the lanthanide chelates of 1,1,1-trifluoro-5,5-dimethyl-

2,4-hexanedione. They found that fluorine migration occurred, as reported for many previous lanthanide chelates, but also observed migration of the tertiary butyl R-group to the metal. They also found 48,49,83 cleavage of CF 3, c4H9, and c4H6 groups. 15 Cea Olivares et al. reported the mass spectra of the europium(III) chelates of fluorinated B-diketones substituted with methyl, ethyl, iso-propyl, and iso-butyl (R group). For these chelates there was the loss of both the R group and CF 3 from the molecular ion; a 11 t e h oth er f ragmentations. are as given. b y L.ivingstone . e t a~..., 24, 56

(Figure 5.3).

II. Results and Discussion

The mass spectra of sixty lanthanide chelates have been obtained.

In all cases the molecular ion was found to be due to the anhydrous tris chelate, even though the hydrated compounds were placed in the mass spectrometer. The coordinated waters were removed by the very low pressures obtained in the mass spectrometer.

The high molecular weight, and the relatively low volatility of the

complexes made the mass spectra difficult to obtain. Complexes of 1,1,1-

trifluoro-5,5-dimethyl-2,4-hexanedione gave the best mass spectra with

high intensities of the metal-containing peaks. The mass spectra of

complexes of 4,4,4-trifluoro-1-(4'-bromophenyl)-l,3-butanedione, which

have the highest molecular weight of all the complexes prepared, were of R""'/C=O -•CF3 J -CH CO r+ --~. H2 C --2 -~> R -C =O \+ C=O 1-co

M-CF I + 3 R M

0 0 II II C C Rj "'-cH II+ C H 11~--RH~ I ".rye CH 0 II 0

M-CF 3-RH

Figure 5.4. Mechanism for the fragmentation of the B-diketones 111

very low intensity, if they could be obtained at all. The remaining complexes gave·variable spectra, which were usually of medium intensity.

The mass spectra of the ligands are superimposed on to the mass spectra of the complexes. The mass spectra of the fluorinated 8- diketones 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedione, 23 4,4,4- trifluoro-1-(4'-bromophenyl)-1,3-outanedione23 and 1,1,1-trifluoro-5,5- dimethyl-2,4-hexanedione31 have been·reported. The ligands fragment in essentially the same manner. The molecular ion, HL~ fragments to give

M-CF 3, RCO~ R~ and m/e 69 as the major peaks. It was found that the mass spectra of 4,4,4-trifluoro-1-(3'-methylphenyl)-1,3-butanedione and

4,4,4-trifluoro-1-(2'-methylphenyl)-1,3-butanedione were virtually identical with the mass spectrum of the 4'-methylphenyl substituted

8-diketone obtained by Das and Livingstone. 23 The mechanism for the fragmentation of the fluorinated 8-diketones is given in Figure 5.4.

The peak observed at m/e 69 may be due to either of the ions CF; or

The ligand peaks are easily distinguishable from the metal containing peaks in most cases, as many lanthanides have a large distribution of natural isotopes. The mass spectra of sixty lanthanide chelates and the metastables observed are listed in Tables 5.1 to 5.9. The relative intensities are calculated in relation to the largest metal- containing peak (100%). The relative intensity takes into account the isotopic distribution of each ion; this is more accurate than selecting a particular isotope and measuring only it for the whole spectrum. Even so, the relative intensities are not accurate enough to indicate anything more than general trends, as each spectrum takes about thirty seconds to run for the whole molecular weight range. The isotopic distribution observed deviates less than 5% from the calculated distribution in most cases. The isotopic distribution of each lanthanide and the tris chelates

N N

I-' I-'

8 8

7 7

5 5

6 6 5 5

21 21 76 76

11 11

58 58 21 21

34 34

Yb Yb

41 41 19 19

11 11

100 100

Chelates Chelates

3 3 2 2

1 1

7 7

1 1

6 6

16 16

81 81

12 12

13 13

67 67

Tm Tm

100 100

3 3 2

8 8

8 8 1

Metal Metal

24 24

80 80

55 55

Er Er

16 16

41 41

33 33 14 14

32 32

31 31 59 59

100 100

the the

1 1

- 3 3

4 4

5 5

35 35

20 20 59 59

16 16

of of

25 25

Ho Ho

13 13

21 21

44 44

100 100

4 4 1

4 4 5 5

8 8

21 21

Dy Dy

54 54

26 26

37 37

13 13

63 63 21 21

50 50

16 16

100 100

Spectra Spectra

7 7

8 8

- 19 19

10 10

17 17

28 28

17 17

12 12

33 33

Tb Tb

100 100

Mass Mass

the the

19 19 32 32

52 52

15 15

13 13

35 35

12 12

13 13

55 55

84 84

Gd Gd

100 100

in in

9 9

5.1 5.1

39 39

Eu Eu

32 32

39 39

23 23 65 65

23 23 32 32

48 48

Ions Ions

100 100

2 2

29 29

95 95

Sm Sm 51 51

48 48

Table Table

39 39

97 97

55 55

42 42

11 11

14 14

35 35

100 100

72 72

26 26

16 16

46 46

73 73

Nd Nd

33 33

44 44

59 59

58 58

100 100

8 8

Pr Pr

33 33

16 16 91 91

24 24

Metal-containing Metal-containing

37 37 -

30 30

58 58

80 80 57 57

100 100

1 1

3 3

8 8

6 6

18 18

20 20

51 51

17 17

25 25

Ce Ce

30 30

97 97

10 10

63 63

Major Major

100 100

of of

7 7

La La

12 12

20 20 40 40

12 12

61 61

35 35

99 99

38 38

67 67

100 100

2 2 2

4 4

8 8

4 4

8 8

22 22

13 13

y y

42 42

66 66

14 14

36 36

11 11

10 10

100 100

Intensities Intensities

2 2

4,4,4-trifluoro-l-(2'-thienyl)-l,3-butanedione 4,4,4-trifluoro-l-(2'-thienyl)-l,3-butanedione

(MetF2) (MetF2)

-co

of of

Relative Relative

(MetF) (MetF)

2 2

3 3

Ion Ion

M M

M-RCOF

M-CF

M-L+F M-L+F

M-L-CO M-L-CO

M-L M-L

M-L-CF

M-L+F-CF M-L+F-CF

M-L-CFz-CO M-L-CFz-CO

M-321 M-321

M-2L+2F M-2L+2F

M-L-RCO-F M-L-RCO-F

M-2L+F M-2L+F

M-2L+F-CF2 M-2L+F-CF2

M-2L+F-CO M-2L+F-CO

M-2L+F-CF

Met-3L+F Met-3L+F Met-3L+2F Met-3L+2F

......

l,.) l,.)

Yb Yb

/ /

Tm Tm

/ /

./ ./

.// .//

Er Er

/ /

// //

/ /

// //

the the

Ho Ho

/ /

of of

Dy Dy

/ /

./ ./

/ /

../ ../

Tb Tb

/ /

Spectra Spectra

Gd Gd

/ /

./ ./

../ ../

Mass Mass

5.2 5.2

the the -

- Eu Eu

in in

Table Table

Sm Sm

/ /

✓ ✓

/ /

4,4,4-trifluoro-l-(2'-thienyl)-

of of

- -

Nd Nd

Observed Observed

Pr Pr

✓ ✓

/ / / /

Peaks Peaks

Chelates Chelates

Ce Ce

/ /

✓ ✓

,/ ,/

/ /

La La

- -

/ /

./ ./

/ /

./ ./

Lanthanide Lanthanide 1,3-butanedione 1,3-butanedione

Metastable Metastable

y y

/ /

./ ./ / /

/ /

MetFz MetFz

+ +

M-2L+F M-2L+F

M-2L+F-CFz M-2L+F-CFz

M-2L+F M-2L+F

M-2L+F-CO M-2L+F-CO

3 3

-+ -+

+M-L +M-L

M-L-CO M-L-CO

M-L-RCOF M-L-RCOF

-+ -+

3 3

M-CF

M-L+F M-L+F

M-L M-L

-+ -+

+ +

M-2L+F-CFz-COz M-2L+F-CFz-COz

M M

M-2L+F-CFz-+ M-2L+F-CFz-+

M M M-2L+F-CFz M-2L+F-CFz

M-2L+F-+ M-2L+F-+

M M

M-CF

M-L M-L

M-L-CO M-L-CO

M-L-CF M-2L+F-+ M-2L+F-+ 114

Table 5.3 Relative Intensities of Major Metal Containing Ions in the Mass Spectra of the Lanthanide Chelates of 4,4,4-trifluoro-l-(4'-bromophenyl)-1,3-butanedione

yA Ce Pr8 Eu Dy Ho8 Er TmA Yb 8

M 100 47 100 18 96 100 100 72 100 M-CF 2 3 M-CF 3 57 25 8 46 58 59 41 47 M-86 33 12 2 100 27 - 100 14 M-L+F 10 100 M-L 38 10 56 20 43 31 26 30 18 M-L-CO 5 4 7 4 12 9 7 8 5 M-L-CF 2 57 11 20 12 31 32 26 31 17 M-L-RCOF 76 9 23 17 4 1 1 1 M-2L+2F 10 M-2L+F 61 43 so 34 ? 19 12 15 6 M-2L 12 M-2L+F-CO 19 13 13 10 7 3 3 M-2L-CF 2 10 M-2L+F-CF 2 95 37 43 45 ? 49 29 37 17 M-2L+F-CF 2-co2 38 13 6 MetF 2 81 100 32 24 28 19 18 19 2 MetF 100 0 0 0 0 1

A.metastable observed for M + M-CF 3

B.metastables observed for M + M-CF 3 and M-CF 3 + M-L I-'

I-' V,

7 3

5 4

9 4 1

16 85 19

100

the

36 98

Tm 38 29 91

100

91 28 Spectra 39 Er 16

17 25

Mass

3 4 4

3 6 7 4

9 4

16 57 21

100 100 the

3 9

6 5

Dy 26 13

35 11 11

100

Ions

5 4

42 17 Tb 33 26 15

100

5.4

Containing

5 5 4

Gd 22 46

14 21 38

100

Table

Metal

- 4 - -

- -

Eu 49 19 51

15 43 49

63 48

100

Major

4,4,4-trifluoro-1-(3'-methylphenyl)-1,3-butanedione.

4 - -

of Sm 16

58 64

33 14

40 20 76

100 of

4 - -

72 45

Nd 18

20 40 25

61 30

100

Chelates

Intensities

----

- 37

10 54 18 16

29 11

100

Lanthanide Relative 78

- 38 -

- 18

Ce 4

38 24

31 90

44 88 71

100

4 -

- 3 -

99 26

11 17

28 25

100

Ion

M-CF

M M-CF3 M-RCOF2

M-L M-L+F M-L-CO

M-L+F-CF

M-L-CF2 M-L-RCOF M-329 M-2L+2F M-2L+F M-2L M-2L+F-CO M-2L+2F-CF M-2L+F-CF2-C02 M-2L+F-CF2 MetF MetF I-' I-'

/ -

Yb /

/ ✓ ./

Chelates

./ ../

Ho --

-- -

Lanthanide

-- -

Tb -

the

- Gd -

5.5

- / Eu ✓ - --

Spectra

3-butanedione.

Table - ✓ /

Mass

- /

../ /

the

- Pr

- -

- - -

✓

Ce - - -

Observed

✓ ./_

Peaks

4-trifluoro-l·J'(-methylphenyl)-1,

4, 4, 4,

Metastable

MetF

M-2L+F-CFz-COz

M-L-CFz-CO

M-2L+F-CF

M-L

M-L-RCOF

M-CF

M-L

M M-L M-CF3

M-L-CFz M-2L+F-CFz M-2L+F

M-2L+F-CFz-COz 117

Table 5.6

Rel.ative Intensities of Major Metal Containing Ions in the Mass Spectra of the Lanthanide details of 4,4,4-trifluoro-l-(2'-methylphenyl)-l,3-butanedione.

y Ce Pr Sm Eu Gd Tb Dy Yb

M 10 100 11 5 6 7 9 8 17

M-HF 70 73 58 4 100 100 81 100

M-2HF 8 6 13 2 10 10 51 14

M-CF 5 1 3 4 2 7 6 5 7 3 M-R 1 6 4

M-RCDF 2 7 2 20 13 4 13 10 12 6

M-HF-RCOF 2(?) 4 5 5 6 5 5 4 M-L+F 2

M-L 5 5 21 13 100 10 14 52 4

M-HL-HF(?) 100 33 100 100 6 78 97 100 67

M-L-CO 7 3 10 14 7 10 10 7 5

M-HL- 2HF(?) 18 2 18 19 18 16 27 17

M-L-CF 2 19 6 27 15 15 15 19 15 14

M-HL-CF 2-HF 8 1 4 6 2 5 5 13 6 M-2L+F 37 20 83 30 30 24 35 13 13

M-2L 91

M-2L+F-CO 15 7 32 12 10 4

M-2L+F-CF 2 95 17 92 41 40 38 SS 13 26

M-2L-CF 2 15

M-2L+F-CFf=02 60 3 20 17 10 17 29 15 15

MetF 2 73 11 90 29 2 17 20 11 4 MetF 6 19 4 118

Table 5.7 Metastable Peaks Observed in the Mass Spectra of the Lanthanide Chelates of 4,4,4-trifuloro-1-(2'-methylphenyl)-1,3-butanedione.

y Ce Pr Sm Eu Gd Tb Dy Yb

M-+- M-HF - ✓ ✓ ✓ / ✓ ✓ ✓ ✓

M-+- M-L ✓ ✓ M-HF-+- M-2HF ./ ./ ✓ I ✓ ✓ M-HF-+- M-HL-HF ./ ./ M-CF 3 -+- M-L ../ ./

M-L-+- M-HL-HF ✓ ✓ ✓ ./ ✓ ✓ M-L-+- M-L-CO ./

M-L-CF 2 -+- M-2L+F ./ ✓ M-2L+F-+- M-2L+F-CO ./ ./ M-2L+F-CF 2 -+- M-2L+F-CF 2-co 2 / ./ .....

..... '-0

4 2 2

1 2

77 26 13 Yb

100

Lanthanide

67 38 (0.2) Tm

100

the

5 9 7 2

1 2 3

57 17

100

7 5 5 9

3 2 3

3 1 2

17 79

29 Ho

Spectra

8 6

Dy 11

Mass 10 54 26

100 100

the

9 9 2 1 2

3 3

41 Tb 26

100

9 8

Ions

Gd 11 26 45 12 11

100

5.8

6 8

9 9 2 4 5 4

22 40

12 14

100

Table

7 Containing

5 -

5 8

34 21 10

21 12

100

Metal

7 1 4 -

5 -

Nd 13

14 16

100

Major

6 8

1 -

27 10

100

9 7 --

100

2 1 9

1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione.

12 15 41

100

Intensities

3 --- 6 5 5 - 3 7 -

21 y

92 12

35 10

100

Relative

Chelates

M-R

M-L

M-L-CF M-L-CO MetF

MetF M-2L+F M-L-RCOF M-2L

M-2L+F-CO

M-2L-CO M-2L-CF M-2L+F-CF N

I-'.

✓

./ ./ ✓

✓

../

- -

✓

- -

Ho -

- -

✓

Dq -

✓

/ ,/

✓

1,1,1-

✓

- -

Chelates

✓

✓✓

✓

✓✓

✓

Lanthanide

✓

✓ ./

✓

the

Table

✓

✓ ./

✓ ✓

Spectra

✓

Mass

the

-HF

Observed

M-2L+F-CF

M-2L+F

Peaks

2 M-L-CO-CF

M-2L+F-CO

M-2L+F-CF

M-2L+F

M-L-CO

M-L-CF

M-L

M-L-RCOF

M-R

M-L

M-+

M-L-+

M-L

M-R-+

M-L-CO-+

M-+

M-L-+

M-2L+F-+

M-2L+F-CF

M-L-CF

M-2L+F

M-L-CO-+

~ctastable

:rifluoro-5,5-dimethyl-2,4-hexanedione 121

it forms are given in Table 5.10, The molecular weight of each isotope may be obtained by adding the number at the top of each column to the molecular weight of the lowest significant isotope. Complexes of 4,4,4- trifluoro-l-(4'-bromophenyl)-1,3-butanedione have a larger distribution as bromine has two isotopes 79Br and 81Br, which are present in approximately equal amounts. This property is useful in analysing the mass spectra of the complexes as it gives a definite indication as to how many bromines are present. To calculate the isotopic distributions a BASIC program was written; a listing of the relevant section for the calculations is given in Appendix B.

In contrast to the d-transition elements, which vary considerably for each metal, 3 , 4 , 6 , 25 , 54 , 74 , 60 the mass spectra of each series of lanthanide

Chelates are essen t ia. 11 y simi. ·1 ar. 24,52,56,77,78 There is some dependence upon the way the fluorinated B-diketone is substituted, but nearly all metal-containing peaks can be accommodated by the mechanisms proposed by

Das an d Livingstone. · 24 f or t h e samarium,· europium,. gad o 1·inium . and terb' ium

chelates of 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedione. The mechanism

of fragmentation is given in Figure 5.3. These mechanisms, and slight

modifications of them, give reactions which produce most of the ions observed

in the mass spectra of all complexes studied in this work. The odd-electron

molecular ion, M, begins fragmenting by loss of a •CF3 radical to give a more stable even-electron species. This reaction is confirmed by metastable

peaks for most complexes. For complexes of 1,1,1-trifluoro-5,5-dimethyl-

2,4-hexanedione loss of the •C(CH3) 3 radical is more predominant; this is

as expected due to the higher stability of the •C(CH3) 3 radical in relation

to the •CF3 radical. The loss of •Rand the subsequent loss of

C(0)CHC(0)CF3 has a similar mechanism to •CF 3 loss as given in Figure 5.3.

This has been observed for various europium chelates for R = methyl, ethyl, 122

Table 5.10 Calculated Relative Isotopic Distribution of the Molecular Ions of the Lanthanide Chelates.

Ion (M. W) + 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Ce (140) 100 0 13

Ce(TTB) 3 (803) 100 29 30 8 3 1

Ce(MPB)3(827) 100 37 19 5 1

Ce(BPB)3(1019) 29 12 91 34 100 35 43 14 6 1

Ce (DMH) 3 (725) 100 27 16 4

Nd (142) 100 45 88 31 65 0 21 0 21

Nd(TTB) 3(805) 84 63 100 58 78 24 29 8 21 6 3 1

Nd(MPB) 3(829) 90 74 100 60 74 24 23 8 20 7 2

Nd(BPB) 3(1021) 14 12 58 45 100 66 97 50 62 24 31 10 13 4 1

Nd (DMH) 3 (727) 97 69 100 54 74 18 23 6 21 5 1

Sm (144) 12 0 0 56 42 52 28 0 100 0 85

Sm(TTB) 3 (807) 11 3 2 53 55 69 49 18 100 29 96 27 15 3

Sm(MPB) 3(831) 12 4 1 55 61 69 49 14 100 36 90 32 6

Sm(BPB) 3(1023) 2 0 4 9 11 39 39 63 70 55 96 41 100 35 61 7

Sm(DMH) 3 (729) 12 3 1 5 57 64 43 9 100 27 87 23 3

Eu (151) 92 0 100

Eu(TTB)3(814) 79 23 100 29 16 4 1

Eu(MPB) 3(839) 86 32 100 36 3

Eu(BPB) 3(1030) 16 6 64 25 100 36 70 23 20 6 2

Eu(DMH) 3(738) 89 24 100 26 2

Gd (154) 9 59 82 63 100 0 88

Gd(TTB) 3(817) 6 46 75 72 100 33 81 23 12 3 1

Gd(MPB) 3(842) 6 46 81 75 100 32 74 26 5 1 Gd(BPB) 3(1033) 1 8 14 35 57 65 100 64 97 39 53 17 13 4 1 123

Table 5.1 - Continued

Ion (M.W) + 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Dy (160) 8 67 91 89 100

Dy(TTB) 3(823) 6 48 77 88 100 34 15 4 1

Dy(MPB) 3 (847) 6 50 83 91 100 31 5 1

Dy(BPB) 3 (1039) 1 9 19 44 67 82 100 74 69 31 19 5 1

Dy(DMH) 3 (745) 6 54 91 100 24 3

Er (164) 5 0 100 69 81 0 45

Er(TTB) 3 (827) 4 1 85 83 100 34 53 15 7

Er(MPB) 3 (851) 4 2 89 93 100 31 45 15 3

Er(BPB) 3(1043) 1 0 17 17 62 53 100 63 84 36 38 12 8 2

Er(DMH) 3 (749) 5 1 97 93 100 24 46 12 2

Yb (170) 10 45 69 51 100 0 40

Yb(TTB) 3 (833) 7 37 65 61 100 32 47 13 6 1

Yb(MPB) 3 (857) 8 39 69 64 100 33 38 13 2

Yb(BPB) 3 (1049) 1 7 17 34 61 63 100 62 86 35 38 12 8 1

Yb(DMH) 3 (755) 8 41 70 61 100 25 38 10 1

Met 100 Met (TTB) i +663) 100 29 17 4 1

Met(BPB)3(+687) 100 37 14 5 1 Met (BPB) i +882) 32 13 37 100 34 36 11 4 1

Met (OMH)3 ( +585) 100 27 7 2

Met= Y(89), La(l39), Pr(141), Tb(159), Ho(165), and Tm(169). 124

Figure S.S. Mechanism for Loss of CO from M-L .

• -RCO )

+ HC--C==CF2 I I Met 0 ✓

Figure 5.6. Mechanism for Loss of RCO and F from M-L. 125

15 and other alkyl groups, by Cea Olivares et ai. The loss of •CF3 is facilitated by the three electron withdrawing fluorine atoms which weaken the C-cF3 bond. The ion M-L arises from M-CF 3 by loss of the neutral fragment RC(O)CHCO for which metastable peaks were often observed.

Notably for the chelates of cerium, no (or small) M-CF 3 (or M-R) peaks were observed. This is due to the ability of the cerium to form the +4 ion, so direct loss of a ligand moiety (for which metastables were observed) becomes possible. The cerium chelate of 4,4,4-trifluoro-1-(3'-methylphenyl)-1,3-butanedione loses the :CF2 fragment from the molecular ion. This is again due to the ability of cerium to form the +4 ion and the mechanism is analogous to the loss of :CF2 from M-L for chelates of the other lanthanides. The ion M-CF 2 then loses the fragment RC(O)CHCO to give M-L+F. It seems likely that the other cerium chelates follow a similar mechanism to give M-L+F which was observed in all spectra, despite the absence of the peak M-CF 2 in them. The ion M-L can fragment in three ways:

(a) By loss of the thermodynamically stable CO moiety to yield the ion M-L-CO. The mechanism is given in Figure 5.5. Metastables were observed for many of the complexes of l,l,l-trifluoro-5,5-dimethyl-2,4- hexanedione (Table 5. 9) , but not for any other complexes.

(b) By loss of the fragment RCOF. A metastable corresponding to this transition is often observed. Das and Livingstone. . 24 h ave proposed t h e mechanism shown in Figure 5.6.

M-L-CF 2 with concomitant fluorine migration to the metal atom (Figure 5.3). No metastables have been found, either in this work or any previous work, corresponding to this transition. The reaction presumably occurs due to

the attraction of the positive charge on the metal atom for the electro negative fluorine. 126

The ion M-L-CF2 then loses another RC(O)CHCO (analogous to the loss of the same fragment from M-CF3) to give the ion M-2L+F. Metastables were observed for the 4,4,4-trifluoro-1-(2'-thienyl)-1,3-butanedione complexes (Table 5.3). The M-2L+F can undergo two fragmentation pathways: loss of CO; and loss of :CF2 (Figure 5.3). Both these fragmentations are similar to the loss of the same fragment from the M-L ion.

The ion M-2L+F-CF2 is observed by a limited number of metastables to lose co2. This is presumably by the mechanism given in Figure 5.2, which is different to the mechanism proposed by Das and Livingstone (Figure 5.3), which occurs in two separate steps. Also observed were some metastables + for the loss of RC(O)CHCO to give the MetF; ion. The MetF2 ion was also observed to be formed from the ion M-2L+F-CF2-co2 by loss of RC(O)CH. Metastables for these transitions have not been observed before.

The lanthanides samarium, europium, thulium and ytterbium may exist in the bivalent state as well as the more stable tervalent state. For + chelates of these lanthanides the ion MetF was also observed. It could conceivably arise from either of the ions M-2L+F-CF2 or M-2L+F-CF2-co2, but it seems most likely to arise from the ion MetF2 via a change in metal valency followed by loss of a fluorine radical •F.

III 7+ Met F2 -+ -+

The ions MetF for samarium, thulium and ytterbium, and the ions M-21,

M-2L~cF2, and several other peaks for europium, were the only indications of the formation of the bivalent state in the mass spectrometer. The ion M-2L

which is observed in the mass spectra of the europium(III) chelates

probably arises from the ion M-2L+F by valency change of the europium + followed by the loss of a fluorine radical as for the ion MetF2 . 127

The lanthanides cerium and terbium are known, in addition to the

tervalent state, to exist in the quadrivalent state. The mass spectra of

the terbium chelates showed no indication of formation of the quadrivalent state. The mass spectra of the cerium chelates showed many peaks which contained cerium in the quadrivalent state. The fragmentation pathway

for a typical tervalent only lanthanide is shown in Figure 5.7. By comparison with Figure 5.8, which shows the fragmentation pathway for the

cerium chelates, it can be seen that there are significant variations.

Initially there is no loss of •CF3 (or •R) radicals from the molecular ion, but either the loss of :CF2 or a complete ligand moiety. This is consistent with the ability of cerium to form the quadrivalent ion. The ion M-CF2

then loses the fragment RC(O)CHCO as for the M-L-CF2 ions of the other lanthanides, as shown in Figure 5.9. The cerium(IV) ion M-L+F then under-

goes a series of fragmentations without reducing to the cerium(III) state.

The fragmentations are analogous to the fragmentation of the ion M-L for

the other lanthanide chelates.

The R group generally seems to have little effect upon the mass

spectra.

The methylphenyl

substituted ligands could be expected to have virtually identical spectra

due to rearrangement of the R group into the more stable tropylium ion.

The mass spectra of some of the complexes that display variable valence

in the mass spectrometer and 'typical' examples of complexes of each ligand

are shown in Figures 5.10 to 5.12.

The similarity of the spectra of the para- and meta-methyl substituted

B-diketone complexes is as expected. The mass spectra of complexes of

4,4,4-trifluoro-l-(2'-methylphenyl)-l,3-butanedione, however, are signifi

cantly different (Table 5.9). The methyl group is in the ortho position 128

M 1 M-R M-CF. 3 M-RCOF2 l M-L l M-LrF2 M-L-CO M-L-RCOF M-2L+F

M-2L+F-CO

M-2L+F-CF.2 - 2 CO ~

Figure 5.7. Fragmentation Pathway for Typical Tervalent Chelates. 129

M-L4-F l M-L+rCF2

M-2L+2F M-2L+F j M-2L+2F-CF2 M-2L+F-CO M-2L+ F-CF 2 l M-2L+F-CF.· 2 - 2 CO

Figure 5.8. Fragmentation Pathway for Cerium Chelates. 130

(M- L+F)

Figure 5.9. Mechanism for Fragmentation of Cerium Chelates. 131

100 M- 2L +F

80 (A)

70 M-2L+F-CF2 60 M so M-2L+F-CO ; 40

30 / M-L-RCO-F M-L M-2L+f-CF M-L+F 20 2 M-L-CF 2 -C0 2 M-2L M-L+F -M-L-CO 10 +2F -CF , 2 .. f .. - M-CF3 I I - SOO 600 700 800 - 100 200 300 400

MF· 2 M-2L+F 100

90 ( B)

70 M-2L+F-CF2 M-L 60

M-2L+F-CO so / M 40 ✓ M-L-RCO-F 30 M-L-CO M-L-CF2 I 20 M-2L+f-CF -co 2 I M-CF 3 10 2 M-RCOF 2 I I I I I -... 100 200 300 400 SOO 600 700 800

Figure 5.10. Mass Spectra of Chelates of 4,4,4-trifluoro-1- (2'-thienyl)-1,3-butanedione (A) Cerium chelate (B) Lanthanum Chelate 132

M 100 1 I 90 1 IU

(,ti M

lll l+l '" MetF2 M-2L•F 10

lt1U !OU 3l'U 400 Soll (100 7Utl HIIII 9011 ltJIIU 111111

n1/i:

100 M-2~F-C~ 90 MetF2 M-2L•F 80 M-HF 70 (B) 60

•o

20 ~-L M 10 I I I I I ,' 100 200 300 ,oo sou 600 700 800 90n 1000 ll00 •I•

M I"" ... M-L ( C)

'" M-L-C~ '"

~ el '" I I I ' \1111 .inn ... nn ,,nn -:"011 flflll 91111 I l"lllrl I lflfl ~1,

Figure 5 .1) . (A) Ho(p-BPB) 3 'B, \. J Pr(o-MPB) 3

100

10 (A)

60 so

40 MetF 30 M-2L 20 M-2L-CFi ~ )4-2L-C0 10 ~

100 200 300 400 SOO 600 700 100

100

90 80 ( B) 70

60 so

30.

100 200 300 400 SOO 600 700 800

Fi~ure 5.12. Mass Spectra of Chelates of 1,1,1-trifluoro-5,S dimethyl-2,4-hexanedione (A) Europium chelate (8) Gadolinium Chelate 134

?igure 5.13. Possible orientation of 8-diketone so that - CH3 and CF3 groups are close.

0 0

Figure 5.14. Rearrangement to form Tropylium ion. 135

and the loss of the neutral fragment HF, for which metastable peaks are often observed, must be related to it. It is possible that the odd-electron molecular ion can rearrange so that a fluorine of the -CF3 group and a hydrogen of the ortho -CH3 group are in close proximity. The approach would not be as close for the meta and para substituted analogues

(Figure 5.IJ:). This reaction would be expected to occur in the ligand alone as it is an internal reaction. The mass spectrum of the ligand showed no peak whatsoever for the loss of 20 a.m.u. so it may be postulated

that the loss of HF is due to an inter ligand reaction in the chelate, by a similar mechanism. The crystal structure of the meta-methyl substituted analogue (Figure 2.5) showed the methyl group to be rotated away from the

-CF3 group. If a similar rotation is true for the ortho-methyl substituted

complex, then the methyl group would be in closer proximity to the -cF3 groups of an adjacent ligand moiety. The odd-electron and the positive

charge are probably delocalised throughout most of the molecule so that a

full mechanism is not able to be derived. There is, however, a two-

electron shift from the -CH3 group to form a bond with the adjacent fluorine + of the -cF3 group, which leaves a positive charge on the -CH2 group which rearranges with the phenyl ring to form the tropylium ion (Figure 5.14).

The stability of this ion is presumably the driving force of the reaction.

The loss of 2HF would occur from this reaction occurring for two of the

ligand moieties. The loss of HF is also observed from several other ions

in the spectra (Table 5.9).

The mass spectra of all complexes of 4,4,4-trifluoro-1-(2'-thienyl)

l,3-butanedione and l,l,l-trifluoro-5,5-dimethyl-2,4-hexanedione are given

in Appendix Bin the isotopically corrected form. 136

IV. Experimental

The mass spectra were obtained on an AEI MS12 mass spectrometer at

70 eV. The source temperature was 200°C and the probe temperature was varied for each sample. The accelerating voltage was 8000V for all samples except complexes of 4,4,4-trifluoro-1-(4'-bromophenyl)-1,3- butanedione which were run at 6000V. 137

APPENDIX A

Detailed Magnetic Data 138

Table A.1

Magnetic Data for Two Cerium Chelates and

Two Praseodymium Chelates

Ce(TTB)3.2H20 Pr(TTB)3.2H20

Temp 6 1/x I 106 I 10 xr.1 M µB XM 11xr.1 µB (K) (cgs) (cgs-1) (B.M) (cgs) (cgs-1) (B .M)

98.9 5026 199 1.99 11498 87 3.02

127.6 4324 231 2.10 9609 104 3.13

156.5 3773 265 2.17 8193 122 3.20

186.1 3370 297 2.22 7073 141 3.22

215.6 3057 327 2.30 6277 159 3.29

244.9 2878 348 2.37 5575 179 3.30

275.0 2654 377 2.42 5090 196 3.35

304.4 2445 409 2.44 4631 216 3.36

Ce(m-MPB) 3 .2H20 Pr(o-MPB).2H20

91.0 4664 214 1.84

98.9 10680 94 2.91 127.6 3501 286 1.89 8998 111 3.03

186.1 2584 387 1.96 6795 147 3.18

244.9 2064 484 2.01 5455 183 3.27

304.4 1777 563 2.08 4682 214 3.38 139

Table A.2

Magnetic Data for Two Neodymium Chelates and Two Gadolinium Chelates

Nd(TTB) 3 .2H2o Gd(TTB) 3 .2H2o Temp. 106xM 1/xM µB 103xa 1/xM µB

(K) (cgs) (cgs-1) (B.M) (cgs) (cgs-1) (B.M)

09.9 11806 85 3.06 77 .8 12.9 7.85

127.6 9730 103 3.15 62.6 16.0 7.99

156.5 8190 122 3.20 51.9 19.3 8.06

186.1 7224 138 3.25 43.6 22.9 8.05

215.6 6341 158 3.31 37.4 26.7 8.03

244.9 5745 174 3.35 32.8 30.4 8.02

275.0 5169 193 3.37 29.1 34.3 8.01

304.4 4738 211 3.40 26.4 37.9 8.01

Nd(DMH)3.2H20 Gd(m-MPB)3.2H20

89.1 12340 81 2.97

98.9 77.5 12.9 7.83

127.6 10210 98 3.23 60.2 16.6 7.84

156.5 47.3 21.1 7.70

186.1 7653 131 3.38 40.9 24.4 7.81

215.6 35.4 28.3 7.81

244.9 6129 163 3.46 31.0 32.3 7.79

275.0 27.8 36.0 7.81

304.4 5232 191 3.56 24.9 40.1 7.79 140

Table A.3

Magnetic Data for Two Terbium and

Two Dysprosium Chelates

Tb(TTB) 3 .2H20 Dy(TTB)3.2H2o Temp. rn3x• 1/x' 103x 1 M M µeff M 1/Xr.i µeff (cgs) (cgs-1) (B.M) (cgs) (cgs-1) (B.M)

98.9 114 8.7 9.51 136 7.3 10.38

127.6 89 11. 2 9.54 109 9.2 10.55

156.5 73 13.7 9.55 89 11.3 10.54

186.1 61 16.4 9.52 76 13.2 10.61

215.6 55 18.4 9.69 65 15.4 10.59

244.9 48 20.9 9.68 57 17.5 10.60

275.0 43 23.5 9.68 51 19.6 10.60

304.4 39 25.9 9.69 46 21.6 10 .61

Tb(o-MPB) 3 .2H20 Dy(p-BPB) 3 .2H20

98.9 112 8.9 9.43 112 8.9 9.42

127.6 85 11. 7 9.34 99 10.1

69 14.4 10.16

215.6 51 19.6 9.37 61 16.4 10.27

244.9 53 19.0 10.17

275.0 40 24.9 9.40 47 21.2 10.18

304.4 37 27.0 9.49 42 24.0 10.06 141

Table A.4

Magnetic Data for Two Holmium Chelates and Two Erbium Chelates

Temp 1/ Xr.f ~ 103 Xr.f 1/Xt.'t ~ (K) (cgs) (cgs-1) (B .M) (cgs) (cgs-1) (B.M)

98.9 128 7.8 10.07 105 9.5 9.12

127.6 101 9.9 10.16 82 12.2 9.14

156.5 83 12.0 10.21 68 14.7 9.22

186.1 71 14.2 10.26 49 20.6

215.6 61 16.4 10.27 51 19.8 9.34

244.9 54 18.6 10.27 45 22.4 9.36

275.0 48 20.9 10.26 36 28.0

304.4 43 23.1 10.27 36 27.5 9.40

Ho(o-MPB) 3.2H20 Er(DMH) 3.2H2o

98.9 123 8.2 9.85 104 9.6 9.07

127.6 98 10.3 9.98

156.0 68 14.8 9.20

186.1 68 14.7 10.07

215.6 51 19.7 9.36

244.9 52 19.2 10.11

275.0 40 25.0 9.39

304.4 42 23.8 10 .11 34 29.8 9.04 142

Table A.5

Magnetic Data for Two Thulium Chelates and Two Ytterbium Chelates

Tm(TTB) 3 . 2H20 Yb(TTB) 3 .2H20

3 Temp 1/xM µ8 10 xM 1/xM µa -1 (K) (cgs) (cgs-1) (B.M) (cgs) (cgs ) B.M)

98.9 63.0 15.9 7.06 20.1: 49.8 3.99

1276 51.6 19.4 7.26 16.2 61.8 4.06

156.5 41.0 24.4 7.16 13.6 73.4 4.13

186.1 34.8 28.7 7.15 11.7 85.2 4.15

215.6 30.2 33.1 7.22 10.4 96.3 4.23

244.9 26.8 37.3 7.25 9.2 108.6 4.25

275.0 24.1 41.5 7.28 8.4 119.6 4.29

304.4 21.9 45.8 7.29 7.6 131.2 4.31

Tm(m-MPB) 3 .2H20 Yb(p-BPB) 3 . 2H20

98.9 63.1 15.9 7.06 21.1 47.5 4.08

127.6 49.3 20.3 7.09 17.2 57.9 4.20

156.0 42.0 23.8 7.25 14.7 68.1 4.29

186.1 35.8 28.0 7.30 12.9 77 .8 4.37

215.6 31.3 31.9 7.35 11.4 87.7 4.44

244.9 27.8 36.0 7.38 10.3 97.4 4.48

275.0 24.9 40.2 7.40 9.3 107 .2 4.53

304 .4 22.5 44.4 7.40 8.6 116 .2 4.58 143

APPENDIX B

Detailed Mass Spectra 144

... IO

10 70 y

20 II I. ,_ 100 200 - - SOO 600 700 100 - 1100

100 IO

IO La ..70 so

40 JO

i I . I ~ F 100 200 )00 400 SOO 600 700 100 900 1000 1100

100

IO 10 Ce 70

10 I I L I 100 :?00 )00 coo 500 ♦00 70~ 100 oou JOOI) 1100

Figure 8.1. Mass Spectra of the Yttrium,Lanthanum and Cerium Chelates of 4,4,4-trifluoro-l-(2'-thienyl)-l,3-butanedione. 145

IIO •.. ,. .. Pr 40

II I I . r 100 JOO - 11111 ... 70D 100 - uoo

100 •.. ..,. .. Nd •• JO

I L r 100 JOO JOO •oo 600 IOU - IOIIU IIUO

1D0 • IO ,. .. Sm so •o JO

10 l I . I r 100 zoo JOO - 700 - - 1000 1100

Figure B.2. Mass Spectra of the Praseodymium, Neodymium and Samarium Chelates of 4,4,4-trifluoro-l-(2'-thienyl)-l,3-butane

IIO '° IO

IO Eu '° JO a

I ~ , IIO JOO IOO 7IO IOO 900 1000 1100 - - -'•

IIO

IO 50 . Gd

40 so

900 1000 1100 100 200 SOO 400 500 600 700 100 ■ fc

IIO IO

60 Tb

40 so

:IO

100 200 700 100 too 1000 1100

Figure 8.3. Mass Spectra of the Europium, Gadolinium and Terbium Chelates of 4,4,4-trifluoro-l-(2'-thienyl)-1,3-butanedione. 147

11111 ,a

Ill

711 '° Dy IO •o JO {'-:t JO

10 I. I I I I I ' 1ono 100 son 61111 7on ion .,.

110

Ill

711

IO Ho '° JO

100 200 JOO 700 100 900 1000 1100 ale

100

60 so Er ,o

10 I I I II I 100 :nn ~00 fl.Otl ~00 1111n a.'r

Figure B.4. Mass Spectra of the Dysprosium, Holmium and Erbium Chelates of 4,4,4-trifluoro-l-(2'-thienyl)-l,3-butanedione. 148

100

70 .. Tm .. JO

1100 100 200 300 •oo 500 600 700 IOO IOO IOOII

100

IO .

70 .. Yb so ~o JO ' 20

10 I I I ·rl r I ~ w 100 zoo JOO JOO 600 100 IOO 900 1000 1100

Figure B.S. Mass Spectra of the Thulium and Ytterbium Chelates of 4,4,4-trifluoro-l-(2'-thienyl)-l,3-butanedione. 149

..,. -,. • ..• • •.. -I - I -I - .. I .. I ,. - ,.

..,. •.. • ao.

100 ,... ..'JO ..so JO

100 200 JOO ,oo SOD 600 700 IOO 900 1100 al•

-i:~ure B. 6. Mass Spectra of the Yttrium, Lanthanum and Cerium Chelates of l,1,l-trifluoro-5,5-dimethyl-2,4-hexanedione. 150

100 " IO

70 '° so Pr •o JO

10 100 200 SOO SOO - 700 IOO - 1000 1100

100 " IO

IO so Nd

~ JO

10 100 200 - 700 IOO - 1000 1100

100 '° IO

70 '° so Sm •o so

10 MetF

100 100 SOD 500 700 100 ,00 1000 1100 - ale

Figure 8.7. Mass Spectra of the Praseodymium, Neodymium and Samarium Chelates of 1,1,1-trifluoro-S,S-dimethyl-2,4-hexanedione. 151

100 '°.. 70 '° .. Eu HetF H-2L 211 ~2L-CFz .. ~ -2L-C0 100 200 ·"" "4W 700 Ill(, SOO 100D llotl - - al•

100 '° IO

70 '° so Gd •o

JO.

100 zoo JOO SOO 600 700 IOO 1000 IIDD - •I•

100

ICI so Tb

10 I 1 11.I I I I 100 200 SOO SOO ICIO 7DO 100 - 1000 .,.

Figure B.8. Mass Spectra of the Europium, Gadolinium and Terbium Chelates of 1,1,1-trifluoro-S,S-dimethyl-2,4-hexanedione. 152

11111 to

60 ..IO Dy JO

10 I I I I I I 100 200 .SOO SOO 600 700 ICICI 900 1000 UDO a/•

lDO ..to ,. '° ..IO Ho JO

100 200 .SOO 400 SOO 600 700 100 900 1000 11DO al•

1DO to

60 so Er ,o

100 200 JOO SOO 600 100 100 ,oo 1000 11no

Figure B.9. Mass Spectra of the Dysprosium, Holmium and Erbium Chelates of 1,1,1-trifluoro-5,S-dimethyl-2,4-hexanedione. 153

100

60 ..so Tm JO

ID Met~

100 200 JOO :' ~00 SOO 700 100 ,00 1000 11on - al•

100 ,0.. ,. '° ..so Yb JO

10 MetF I . I I • I .I 100 21111 JOO SOO 600 700 100 . too lDOO 1100 ale

Figure B.10. Mass Spectra of the Thulium and Ytterbium Chelates of 1,1,1-trifluoro-S,S-dimethyl-2,4-hexanedione. 154

Calculation of Isotopic Distributions

The program used had data files which stored the natural isotopic

distribution for the lanthanides and other elements. This reduced the amount of input required from the operator.

The natural isotopic distribution of the lanthanides was stored in

the array '1', i.e. for cerium: 1(1) = 0.8848

1(2) = 0.0000

1(3) = 0.1107

1(1) is the lowest significant isotope.

The isotopic distributions due to each of the different elements

(carbon, sulfur, bromine, etc.) were calculated separately. For each

element involved the isotopic distribution was obtained and stored in the

variables 'I' 'Il' and 'I2', i.e. for carbon: I= 0.9889

I1 = 0.0111

12 = 0.0000

Also required is the number of atoms of each element, 'N'. The BASIC sub-

routine below then runs for each element involved (other than the lanthanide)

then requires fresh values of 'I', 'Il', 'I2' and 'N' for any other elements

involved.

200 Rem Subroutine Distribute 210 for x=l to N 220 T(1)=1(1)*I 230 T(2)=1(2)*I+L(l)*Il 240 for y=3 to D 250 T(y)=1(y)*I+1(y-l)*Il+L(y-2)*I2 260 next y 270 for y=l to D 280 L(y)=T(y) 290 next y 300 next x 310 return 155

This gave the isotopic distribution in the array 'L'. When the program had been run for all elements contained in the complex, the array was printed. It was found more useful to print the array as relative abundance, by dividing by the isotope with the highest abundance in the complex.

The variable 'D' in the program indicates the number of isotopes to be calculated. · It was present to reduce the number of steps done by the

~omputer if the lanthanide distribution was small. The program works by taking the natural isotopic distribution of the appropriate lanthanide and individually adjusting for the isotopic distribution of each of the other atoms (carbon, bromine, etc.). The temporary array, 'T', was necessary to avoid calculations using the redistributed values of the following isotopes. The temporary array then replaced array 'L'; the process was repeated until all atoms of one kind had been distributed. For each new type of atom it was necessary to input its isotopic distribution. Expected page number is not in the original print copy.(Page 156-159) 160

APPENDIX C

Atomic Positions and Thermal

Parameters of Crystal Structure 161

Dt&ouoTAISl•44•TAlrLUOAO-l•C3'•METHYLPHEHYL1•l•~-8UTANDIONATOIEA8lUMIJIIIHYDAATE ATOMlC P,AAAM[T[RS AND STANOAAO OEViATlONS 2 Tttt ui1soiRo,1c T£MPEAATUAE ,acfo11 is·u,;-cla~1 • ic 2H2 • L Ill·• 2HIC81Z • 2HLl13 • ZICL82lll . 1/A YII ZIC Ill uz. 833 112 11~ 823 ·

DI ,3016101 ,1051101 ,4550COI 00042 COi o0029COI oOCJllCOI -.000210, .ooooco, .oouco, OU o.624?161 ,133115_1 ,5411141 ,00601?1 o0046C41 ,0023131 -.00011 ♦ 1 •00001 llt ,0003 Ill ozi .,ltllC61 ,0929151 ,!5!63161 ,0051111 ,0046141 ,0021131 -.00011 ♦ 1 ,0001 llt .0002121 Cli ,UOIII0I ,1211111 06139161 ·.001s11u _o00l.2CSI .• 0021 C4t •,0007161 -.ooo4cs, -',0001131 Cli ,33401101 ,0913(11 ,6!515C6t' .oo•~i101 ,0046161 ,0016 Ill -.0001161 .•.0006151 ~,0003C41 C3A ,ZlOICUI ,0892111 ,6~21 C61 ,0011 UZI ,0033151 ,0019141 -.0001111 .00101s1 ... 0002131 c•i ,12121111 .ou11iot .,10,111 .oossuot .. ~084191 .,0030141 •,0015 CBI -.0001151 •• 0003151 CSi ,54.11191 ,1343C1t' ,1502111 ,00!58191 ,0036151 ,0020131 -,0004161 -.0001151 •oOOOICll c,, ,H14Cl01 ,1164CII .,200161 ,00!511101 .00•1151 ,0029141 •,0009161 •,00031!51 • 0003 141 c,, .,?3661111 ,1991111 ,6412111 ,OOT9Clll ,0034161 ,0041161 -.0002161 ·-.0005111 •• 0011151 CIA ,?'34(121 ,15'9191 ,T!15lll 000721121 ,OOTO Ill 00034151 ,0004111 -.0021111 •00020 est-. Cti ,HZlCUI ,1042(101 ,1424111 ,00!31141 ,0085110) ·.ooz4 C4t ,Q008191 •,0009161 .00011s1 ·cUi ,5?3211U ,09l3CII .1111111 oOOTOUU ,006lcr1 ,0024141 .oou11, -.000~151 •• 0005141 cli, ,11661121 ,25451111 -•~4ec~u ,00801131 ,006!19) ,0016191 •• oci29c91 •,0009191 •00000(11 '1i ,0?13 •,0114 ·015~6 .ouo ... .., ,0046 •• 00~9 .001~ ... 0000 n, ,15?5 ,0595 ,T!62 ,0101 _,0126 ,0023 •,0024 ,0015 .0010 n;, ,0500 .1210 ,6617 ,0096 ,0107 ,0072 .oo~J .00~1 .0022 .oli _,2?521?> ,IU3C51 ollZIC41 ,0019111 ,OOUC41 .0011121 -.ooose ♦, ,0006141 -~0000121 OIi ,1'.'131161 ,0971(41 ,404tC4t o0054111 ,0036131 ,0032131 •• 00001•1 ,001~141 .oooacl1 CII .,32951111 .1211111 ,2134161 · • OO!I·, 121 00026151 .,0024141 .oooac,i 00017161 ,000lC41 c2i _,45UCIU el4HC91 o2910C11 ,007~ 1121 ,OOSlCTI . ,0034151 -.0002111 .000~1•1 .oou 151 C31 .,5121110> ,1316(71 ol~IOCTI ,00!591101 ,0033151 ,0034151 -.0001161 ,0014161 .·0001 •• , · c•• ...1,1121 •1513CII 03467191 ,OU2Cl41' ,0024151 ,0063171 -.0014111 ,0046181 .0000151 cti ,26411111 ,137'11'1 ,Zl33C61 ,00951121 ,003!5151 -,0011131 -.0002111 ,00031!51 -•• 0001141 c.. , 1150 Clll ...... , ,2034111 ,01191151 ,0057111 . ,0024161 .oo~TCII -.0005161 ·,0009141 c:,a ,09601161 ,0955191 ,1311 Ill ,0160Clll ,0050171 ,0028151 ,0013191 :..0010111 .0001151 Cl8 ,14511111 ,l42?11U .08~9111 ,OZZ31251 ,0070191 ,00201!51 .oo~ ♦ eu1 •00021191 .•• 0000161 C91 ,23931161 ,1899191 .ono111 ,020TC2ll .0041 en ,00341!51 ,0004C10t •0000619) .-0001151 ClOI ,30511161 ,1841 C91 .1101111 ,01101191 ,0046161 ,0022141 ,0021191 00012111 .0010151 Clil •,00?61151 .ouoci21 .1~971101 ,01231111 ,00931111 ,0053111 -.oouu21 •000321101 00003181 ,., ,101' ,0965 .,3106 ,0093 ,0091 ,0101 .0012 .oooa ,0035 '21 ,H50 .2221 ,3271 ,0116 ,0091 ,0126 -,0035 •,0005 oOOlo ,31 ,6164 ,1196 ,21?5 00180 00194 .ooee •00010 ,0042 -,0025 OIC ,3553161 ,2376141 ,43191•1 ,0061161 ,002,1131 ,0030,31 .0001141 •■ 0002 Ill .0001121 ozc ,1349161 ,1801151 .43~0141 ,0056161 ,0035 Cll ,0034131 .0002141 oooos1J1 .0007 Ill Clc: ,31591111 ,3002171 ,4106161 .00••1121 ,00l4C!51 .,0017131 -,0005(6) .0001 (51 ;ooo 11•> C2c ,19101101 ,3034191 ,3!!36111 ,0062UOI 00052111 ,0037151 ,0006111 -.0001111 .,0015 CSI CJc ,1229191 ,2469111 ,3918(61 .oo~r191 ,00421!51 ,0026141 ,0003161 •00006151 .00011•1 c:•c •,00241121 ,25911101 ,3695110~ ,0083Clll .,oos2c11 ,0014181 -.0011191 . •00007191 .0034111 C5c ,39311101 ,3721111 ,4037161 .oonnu ,0030151 .,0023141 .,0013161 ,0006151 -.00011•1 C6C ,50361111 ,36!57181 ,4215111 ,OOIZC121 o.0033151 ,0030141 •oOciooc,i .000~1•1 .0001141 C!C ,58551121 04289191 04261111 .01011131 .000161 ,0033151 •,0021 Ill .000111, ••0003151 CIC ,54351151 ,!5018191 03~93191 ,01~1Cl91 -~0•1111 ,0046161 -.00•01101 ,00111191 ... 0003161 ctc ,U ♦ 5Cl61 ,!5106181 .31441101 ,01761201 ,0025161 ,0065181 -,0009191 .oozsuu ,0019161 cioc ,35551121 ,4468181 ,3T69C11 ,o 101 Clll ,0043161 ,0034151 -. 0008181 -.0001161 .ooo,1s1 Clic • 10511151 ,41121131 ,4526ClU ,00911161 .00021121 ,0069191 -,00321111 •o 00071101 ~0013111 ,1c -.0210 ,3241 ,33!1 .ou2 ,0014 ,0088 .0001 •00039 ,0050 nc •,0487 ,1913 ,3492 ,OlOO ,0092 00101 -.0009 --. 0036 .. 0001 nc •,06!59 ,2T!5l .4~19 ,0103 .0111 ,OOIT ,0046 -.ooo• ,0016 00 ,3700161 •00244151 0492!5141 ,0061161 00031131 ,0030131 -.oooz 141 •00004131 ~000S131 OE • 168!5111 00046151 04206141 0007~111 00041141 •0021131 -.0016141 •0000111•1 .00003131 011 .011111101 •00986171 ,49!51 Ill o0111UZI .00121·11 •0092111 •• 001,cii oOO•T181 0002•151 ,1a• ,0!540 ,0351 065~1 ,Olh .0083 ,0063 o.ocioo .0003 0.0000 r2A• ,0194 , 1629 ,6823 ,0166 00013 ,0063 0.0000 ,0003 0.0000 '3a• .11,1 00161 ,131!5 ,0166 00013 ,0063 OoOOOO .oool OoOOOO '11• .,no .un 02126 00166 00083 ,0063 o.oo·oo .oool OoOOOo ,21• ,6694 ,1932 03978 ,0166 ,0083 ,0063 OoOOOO ,0003 OoOOOO '3i• ,6592 ,0792 03271 ,0166 00083 ,0063 0.0000 ,0003 OoOOOO ~le• •,OIOI 02279 ,4016 ,OlH ,0013 ,0063 OoOOOO ,0003 0.0000 nc• -.0221 ,3510 ,3636 ,0166 ,0013 ,0063 0.0000 .ooo~ OoOOOO nc• -.0251 02071 o312i .01•~ ,0013 •0063 0.0000 .ooo~ OoOOOo ., .. Y/8 ZIC 8 XIA Y/8· ZIC 8

HZ& ,3396 00946 o61~s 3o51 H91 o2T72 .2211 00647 6072 H6A ,6116 ,2064 ,5729 3o99 NlOI ,3903 02220 ,1687 5,16 HIA ,1421 ,1!597 oTlOo 5,44 HZC ,lTIT ,l4lo" ,3637 4080 Hti ,TOOl ,0816 .no5 5,91 H6C ,5297 ,3Z09 04502 4oi4 HlOA ,5211 o01H .1~•· •o64 HIC 051:JO ,5257 o•Ol6 11015 HZI o4!510 olTlO oZ641 •oll N9C o•ooz .5629. 03658 7ol3 H61 01399 00556 oZlZ1 5030 NlOC 02146 o••··· ol5•1 501z "'' ,OHl .1454 oos12 To45 162

PUBLICATIONS 298 A. M. Hamer and S. E. Livingstone Transition Met. Chem. 8, 298-304 (1983)

A. Hamann, W.R. Thies and A. K. Shiemke, J. Am. Chem. Soc., Transition Met. Chem., 3, 239 (1978). - <10> D.S. Polcyn and I. Shain: 103, 4073 (1981) and refs. therein. - 13> F. L. Urbach, in H. Siegel Anal. Chem., 38, 370 (1966). (Ed.), Metal Jons in Biological Systems, Dekker New York and Basel, <11> In order make significant a discussion on formal electrode poten 4 Vol. 13 p. 73 and refs. therein. - <> P. Zanello, P.A. Vigato and G. A. tials in nonaqueous solvents variable diffusion potentials must be Mazzocchin, Transition Met. Chem., 7,291 (1982). - <5> D. E. Fenton, eliminated; this was obtained by adding ferrocene as internal stan S. E. Gayda, U. Casellato, P.A. Vigato and M. Vidali, lnorg. Chim. dard<12>. - <12> R.R. Gagne, C. A. Kowal and G. C. Lisensky, Inorg. Acta, 27, 9 (1978). - <6> M. D. Hawley and S. W. Feldberg, J. Phys. Chem., 19, 2854 (1980). - <13>H. Okawa, V. Kasempimolipom and S. Chem., 70, 3459 (1966). - !7> P. Zanello, A. Cinquantini and G. A. Kida, Bull. Chem. Soc. Jpn., 51, 647 (1978). Mazzocchin, J. Electroanal. Chem., 131,215 (1982). - 18> R. Graziani, M. Vidali, U. Casellato and P.A. Vigato, Transition Met. Chem., 3, 99 (1978). - <9> R. Fraziani, M. Vidali, U. Casellato and P.A. Vigato, (Received April 16th, 1983) TMC 956

The Magnetic Moments and Electronic Spectra of Lanthanide Chelates of 2-Thenoyltrifluoroacetone

Andrew M. Hamer and Stanley E. Livingstone* School of Chemistry, University of New South Wales, Kensington, N.S.W. 2033, Australia

Summary Results and Discussion Magnetic and spectral data are reported for the complexes The lanthanide chelates were prepared by a modification of LnL3 • 2 H2O (Ln = lanthanide; LH = 2-thenoyltrifluoro the method of Stites, McCarty, and Quill,(3) as previously acetone ). The magnetic moments of the samarium and described by Livingstone and Zimmermann<4>. The com europium complexes are strongly temperature-dependent. pounds, which were obtained as dihydrates LnL3 • 2 H2O (LH The values of flett for the other lanthanide chelates are close to = 2-thenoyltrifluoroacetone), are listed with their analyses in those reported for other corresponding lanthanide com Table 1. The analyses agree with the formulation as dihy pounds. The values of the Weiss constant 0 for Ln~ • 2H2O drates; nevertheless an attempt was made to determine the (Ln = Gd, Tb, Dy, Ho, Er or Tm) are quite small(< 12 K), degree of hydration by heating the compounds in vacua over while those for Ln = Ce, Pr, Nd or Yb range from 29-104 K. silica gel for 2 h at 78 °C. This led to a loss in weight ranging The visible spectra of the complexes LnL3 · 2 H2O (Ln = Pr, from 3.8% for the dysprosium complex to 6. 7% for the Nd, Sm, Dy, Ho, Er, and Tm) display the usual line-like gadolinium complex (Calcd. loss of 2 H2O, 4.2% ). Conse absorption bands; hypersensitive transitions of Nd, Ho, Er quently, it appears that some decomposition occurs. It has and Tm complexes were observed with extinction coefficients been demonstrated previously that all acetylacetonates of the many times greater than those found for the aqueous ions. lanthanides contain water so tightly bound that its removal leads to decomposition<5>. A crystal structure determination of tris(acetylace Introduction tonato )lanthanum dihydrate showed that the lanthanum atom The lanthanide elements in their tervalent state form stable is eight-coordinate with a distorted square-antiprismatic con complexes only with strongly chelating ligands containing figuration<6>. It seems likely that the thenoyltrifluoroacetone highly electronegative donor atoms, in particular, oxygen< 1, 2>. complexes have a similar structure. Coordination number 8 is These conditions are fulfilled by ~-diketones, which form common for the tervalent lanthanides, although coordination water-insoluble chelates with the lanthanides under controlled numbers 6, 7, 9, 10 and 12 are known for these ions<2>. conditions. This paper reports magnetic and spectral data for the lanthanide chelates formed by 2-thenoyltrifluoroacetone Magnetic measurements (J), which coordinates to metal ions by loss of a proton from its enol from (2). The magnetic moments of most of the lanthanide ions can be calculated by the use of Equation (1)<7>. Unlike the d elec trons of the transition metal llett = g[J(J + 1)]112 (1) ions, the f electrons of the lanthanide ions are almost unaf (I) ( :! ) fected by the chemical environment and the energy levels are the same as in the free ion, due to the very effective shielding by the overlying 5s2 and 5p6 shells. For most of the lanthanide • Author to whom all correspondence should be directed. ions the ground state is separated by many hundreds of cm- 1

0340-4285/83/05 l 0-0298$02 .50/0 © Verlag Chemie GmbH, D-6940 Weinheim, 1983 fransition Met. Chem. 8, 298-304 (1983) Lanthanide chelate of 2-thenoyltrifluoroacetone 299 fable I. Lanthanide complexes of 2-thenoyltrifluoroacetone (LH). 900

Compound Colour % Found (Calcd.) C H Met

~-2Hi0 cream 36.8 2.4 11.8 ~-" (36.6) (2.1) (11.3) La½· 2H2O pale yellow 34.9 2.4 16.2 800 (34.4) (1.9) (16.6) :::C½ · 2H2O orange 34.7 2.6 16.8 (34.3) (1.9) (16.7) ~r½ · 2H2O light green 34.5 2.3 16.6 (34.3) (1.9) (16.8) ~d½ · 2H2O pale blue 33.6 2.3 17.5 (34.2) (1.9) (17.1) 100 200 300 400 pale green 34.2 2.2 17.8 im½ · 2H2O T(Kl (33.9) (1.9) (17.7) Eu½ · 2H2O colourless 33.7 2.2 18.0 Figure I. Plot of 11XM against T for Sm~· 2H2O (XM in c.g.s. units). (33.85) (1.8) (17.85) 3d½ · 2H2O cream 33.8 2.2 18.4 (33.6) (1.9) (18.35) state - and in the case of Eu3+, even the second and third fb½ · 2H2O pale cream 33.2 2.1 19.3 excited states - to be appreciably populated at room tempera (33.6) (1.9) (18.5) ture. Since these excited states have higher J values than the Dy½· 2H2O pale green 33.7 2.2 18.7 ground state, the actual magnetic moments are higher than (33.4) (1.9) (18.85) those calculated by the use of Equation {l) with the value of J flo½ · 2H2O cream 33.2 2.2 19.2 (33.3) (1.9) (19.1) for the ground state. Er½· 2H2O pink 33.3 2.0 19.4 (33.3) (1.9) (19.3) 250 fm½ · 2H2O colourless 32.8 2.2 19.9 (33.2) (1.9) (19.45) ~½ · 2H2O colourless 33.1 1.8 19.8 (33.0) (1.9) (19.8) ~-H rrom the next higher lying state. Under these conditions the 200 magnetic properties can be taken as those of the ground state alone, making the lanthanide ion in a compound act in the same way as the free ion, as far as the f electrons are con- cerned. However, Equation (1) fails to account for the magnetic behaviour of the ions SmH (f) and Eu3+ (f'), where the experimentally determined magnetic moments vary consider- 100 200 300 400 ably with temperature. For these two ions the first excited J T(KI state is sufficiently close in energy to the ground state for this Figure 2. Plot of 11XM against T for Eu~ · 2H2O (XM in c.g.s. units).

Table 2. Magnetic data for lanthanide complexes of 2-thenolytrifluoroacetone (LH)

Experimental Calculated 3 Ln + Ground LnL3 · 2 H2o•> Lni(SO4)3 · 8 H2Odl Ln(C5H 5)/> Hund0 Van Vleckg) b) c) term µ.ff 298 0(•q µ.ff 29R µ.ffb) µeff 29R 0(•q µeff µ.ff

Lal+ 1S0 0 0 0 0 0 Ce3+ 2Fs12 2.43 104 2.82 2.37 2.46 15 2.54 2.56 pr3+ 3H• 3.35 39 3.57 3.47 3.61 37 3.58 3.62 Nd3+ 4l912 3.39 41 3.62 3.52 3.63 72 3.62 3.68 Pm)+ 51. 2.68 2.83 Sm3+ 6H512 1.67 1.53 1.08 0.84 1.55--1.65 Eu3• 7Fo 3.26 0 3.40-3.51 Gd3+ 8s.r12 8.03 2 8.05 7.81 7.98 0 7.94 7.94 Tul+ 7p6 9.69 8 9.81 9.4 9.7 9.7 Dy3• 6H1512 10.61 4 10.69 10.0 15 10.6 10.6 Ho3• 51s 10.27 5 10.37 10.3 10.6 10.6 Er3• 411512 9.40 11 9.57 9.6 9.45 17 9.6 9.6 Tml+ J~ 7.28 9 7.38 7.6 7.6 Ybl• 2p712 4.30 29 4.50 4.4 4.00 21 4.5 4.5 Lul+ •5o 0 0 0 0

~ This work; bl Eqn. (3); ,, Eqn. (4); dl ref. (11); <) ref. ( 12); 0 ref. (13); s> ref. (14). 300 A. M. Hamer and S. E. Livingstone Transition Met. Chem. 8, 298-304 (1983)

1.8 µ = 2.83 Yx' (T + 0) µ9 (4)

1.6 (µ.,ff = µ/µ9) Table 2 also lists magnetic data for the sulphates< 11> and

1.4 cyclopentadienyl complexes. The values of !lett for the complexes LnL3 • 2 H20 are remarkably close to 1.2 those calculated by Hund< 13>and by Van Vleck and Frank<14>, see Table 2. The plots of against T for the samarium and europium 1.0 llXM complexes are shown in Figures 1 and 2. The values of the magnetic moment for the samarium complex range from 1.05 0-8!-o-----:'.100!,:------"200L------l300'------,..Joo µ9 at 99 K to 1.67 µ8 at 288 K, while those for the europium

T(K) complex range from 2.12 µ8 at 99 K, to 3.46 µ8 at 348 K. The plots ofµ against T for these complexes are shown in Figures 3 Figure 3. Plot of magnetic moment as a function of temperature for and 4. The magnetic behaviour of the samarium and europium Sm~· 2H 0. 2 complexes is similar to what has been found for other com pounds of these f5 and f ions, whose magnetic moments are a 3.5 function of temperatureC7>.

Electronic spectra 3.0 The ions La3+ (4f) and Lu3+(4f14) display no absorption l'tn bands in the range 250-1000 nm (40000-10000 cm-1), since they possess closed-shell electronic configurations. And the 2.5 ions Ce3+, Eu3+, Gd3+, and Tb3+ absorb either entirely or very largely in the ultraviolet region, although some terbium com pounds are pale pink. The remaining tervalent lanthanide ions 2.0 Ln3+ absorb in the visible region. The narrow, low-intensity absorption bands of these lanthanide ions have been studied by a number of workers and most of the electronic transitions 1·50~------::,o~o----.,-J20~0----3..Jo_o______.J,oo have been assigned<1S-19>. These line-like absorption bands

T(K) result from 4f transitions which are Laporte forbidden for the free ion but become allowed by interactions produced by Figure 4. Plot of magnetic moment as a function of temperature for external ligand fields that mix in states of opposite parity. EuL3 • 2H20. The energies of the bands in the spectra of lanthanide com pounds are affected only to minor extents when the chemical environment is changed; this can be explained in terms of the Selbin at al. (S) measured the magnetic moments of the anhy effective shielding of the 4f electrons by the outer electron~c drous lanthanide chelates Ln(dpm)3 (dpmH = dipivaloyl c~re. When spectra of lanthanide complexes are compared methane) and their adducts with pyridine, 2,2-bipyridyl, and wtth those of the aquated lanthanide ions, three changes are 1,10-phenanthroline. Their values for !lett are fairly close to observed, all of which are related to alterations in the strength those predicted by Van Vleck;<9) however, the values found for and symmetry of the ligand field. These changes are: (a) small the Weiss constant range from 152 K for Tm(dpmh to 208 K shifts usually toward lower frequencies; (b) splitting of certain for Ho(d~mh; these values seem much too high. Ansari and bands; (c) alteration of specific absorbtivity of individual Ahmad<' have reported the room-temperature magnetic ~ands. ~ose b_ands which are particularly susceptible to sElit moments for the pyrazine adducts Ln(dpm)3 • Pz. tmg and mtens,ty changes are termed "hypersensitive"<'· 0>. The magnetic susceptibilities of the lanthanide chelates of 2- thenoyltrifluoroacetone were determined over the tempera The visible spectra of the complexes Ln~ • 2 H20 (Ln = Pr, ture range 99-304 K; the data are summarized in Table 2 and Nd, Sm, Dy, Ho, Er, or Tm) were obtained from solutions in 95% ethanol. No bands could be assigned above 24000 cm-1 the detailed data are given in the Experimental Section. The since the ligand absorbs strongly in this region. The spectra of com_plexe~, except_ those of samarium and europium, obey the Cune-Wetss law, 1.e., Equation (2). the lanthanide nitrates were also measured for comparison. The data are listed in Table 3 together with the vapour-phase XM = O(T + 0) (2) spectra of Ln(thd)3 (thdH = 2,2,6,6-tetramethyl-3,5-hep tanedione) reported by Gruen et al. (17). The orange colour of It should be noted that the values of the Weiss constant 0 the cerium complex CeL3 • 2 H2o is due to the tail of an although_ listed as positive, are the negative of the intercept o~ intense charge-transfer band in the ultraviolet. the Taxis of the plot of 1/xM; i.e., the intercept occurs below The frequencies of the line-like spectra of Ln~ • 2 H20 (Ln ~ K. The values of 0, except for the cerium complex, are rela = Pr, Nd, Sm, Dy, Ho, Er or Tm) are very close to those tively small. The values of µ at 298 K are calculated from the reported for Ln3+ ( aq) and to what we found for solutions of Curie law, i.e. by use of Equation (3), while those of !lett are Ln(N03h in water. However, in the case of the "hypersensi calculated by the use of Equation (4). tive" bands - viz., 4G 512 and 2G712 for NdL3, 5G6 for HoL3, 2H 1112 for ErL3 and 3~ for TmL3 - splitting of the bands and a µ = 2.83 VXM X T µ9 (3) marked increase in the molar extinction coefficient E was Transition Met. Chem. 8, 298-304 (1983) Lanthanide chelate of 2-thenoyltrifluoroacetone 301

observed. In addition, the (5G, 3G)5 transition of HoL3 splits Analyses into five components with E = ea. 7 M-1 cm - 1, compared with Analyses for carbon and hydrogen were performed by the a value for E of ea. 3 M-1 cm-1 for Ho(N03h in water. Microanalytical Laboratory, School of Chemistry, University of New South Wales. Experimental Metal analyses were done by the complexometric method of Lyle and Rahman<20 after digestion of the metal complex with Preparation of lanthanide complexes a mixture of concentrated sulphuric and nitric acids. The The method used was a modification of that used for the resulting metal sulphate was dissolved in water and the solu preparation of lanthanide acetylacetonato complexes by Stites tion was neutralized with ammonia until a precipitate was et al., <3> as described by Livingstone and Zimmermann<4>. In about to form. Sodium acetate (2 g) was added and the pH was some instances the product was purified by dissolution in adjusted to and kept at 5.8 by the addition of 0.2 M acetic acid methanol and reprecipitation by the slow addition of water. or 0.2 M ammonia. The solution was heated to 70 °C and 2-Thenoyltrifluoroacetone was obtained from Columbia stirred with a mechanical stirrer while being titrated with 0.005 Organic Chemicals, Columbia, South Carolina. M EDTA with xylenol orange as indicator<22>.

Table 3. Spectral data for lanthanide complexes of 2-thenoyltrifluoroacetone (LH)

Praesodymium (4f2)

Electronic pr3+ (aq)•> Pr(NO3h in waterb) Pr½ in 95% EtOHb) Pr( thd)3 (gaseous y> transition•> E(cm-1) E(cm-1) E(M-1 cm-1) E(cm-1) E(M-1 cm-1) E(cm-1) E(M- 1 cm-1)

3 1 H4 ➔ D2 16840 17100 2.3 16900 1.7 16830 0.3 { 17500 0.3 { 17360 0.1 20700 4.4 3.2 3po 20710 20700 5.2 21200 9.1 20490 4.5 lpl 21330 21300 5.5 22400 13.1 20920 4.4 lpl 22540 22600 11.8 { 22600sh 11.4 22120

Neodymium ( 4f)

Electronic Ndi+(aq)•> Nd(NO3h in waterbl Nd½ in 95% EtOHb) Nd(thd)3 (gaseous)<> transition•> E(cm-1) E(cm-1) E(M-1 cm-1) E(cm-1) E(M-1 cm-1) E(cm-1) E(M- 1 cm-1)

4l912 ➔ 4F712 13500 13500 6.9 13500 6.3 13510 2.9 4S312 13500 13700 4.2 13800 5.0 4F912 14700 14700 0.5 14700 1.6 17060sh 34.0 16560sh 14.8 4Gs12 17300 17300sh 5.8 17150 41.3d) 16880 32.8d) 17220sh 39.3 17330sh 19.5 2G112 17460 17400 7.3 17510 27.3d) 17350 22.2d) 18900sh 0.5 ! 18740 7.6 18900 9.8 4 19160 19200 4.7 G112 { 19100 8.1 18780 8.2 19300 4.2 18870 7.1 4 I I G912 19550 19600 1.9 19500 4.5 2K1s12 21000 21000 0.8 20960 2.8 2G912 21300 21300 0.8 4G1112 21650 21700 0.7 lpl/2 23250 23400 1.1 23300 5.1 23150 8.5 Samarium (4f)

3 Electronic Sm •(aq)'1 Sm(NO3h in waterb> Sm½ in 95% EtOHbl Sm(thd)3 (gaseous)<> transition 11 E(cm-1) E(cm-1) E(M- 1 cm-1) E(cm-1) E(M- 1 cm-1) E(cm-1) E(M- 1 cm-1)

6Hs12 ➔ 4Gs12 17900 17860 0.03 18660 0.03 'F312 18900 18900 0.01 18940 0.37 4G112 20050 20040 0.05 20400 1.14 20410 1.3 4M1s12 20800 20870 0.61 20900sh 1.20 'l1112 21100 21300sh 1.41 21370sh 1.6 'l1312 21600 21600 0.56 21690 1.71 'F512 22200 22220 0.03 22270sh 2.16 22930 3.9 23900 0.43 ( 6P, 'P)i12 24050 23870 12.47 24100 0.46 23810 5.8 302 A. M. Hamer and S. E. Livingstone Transition Met. Chem. 8, 298-304 (1983)

Table 3. Contd.

3 Electronic"> Ho +(aq)"' Ho(NO3) 3 in water HoLi in 95% EtOHb' Ho(thd)i (gaseous)'' transition E(cm-1) E(cm-1) E(M- 1 cm-1) E(cm-1) E(M- 1 cm-1) E(cm-1) E(M-1 cm-1)

Dysprosium (4t9)

Electronic Dy3(aq)•l Dy(NO3h in waterh> DyLi in 95% EtOHh> Dy(thd)3 (gaseous)'> transition•> E(cm-1) E(cm-1) E(M-1 cm-1) E(cm-1) E(M- 1 cm-1) E(cm-1) E(M- 1 cm-1)

6H1s12--+ 4F912 21100 22140 0.10 21280sh 0.97 22080 2.55 4 22100 22220 0.26 22030 2.5 l1s12 { 22220sh 2.17 4Gu12 23400 23410 0.11 23530sh

Holmium (4 10) sis--+ 15220 1.16 15200 1.13 5Fs 15500 15310 1.16 15310 1.24 15340 0.7 15620 3.76 15630 2.40 18210sh 0.45 18350sh 2.06 5 18500 18180sh 0.8 S2 18400 2.05 18480sh 2.94 5F4 18500 l18620 5.60 l18660 3.95 18520 1.2 20410sh 0.41 20330sh 0.85 SF) 20600 20510 1.1 20620 2.15 20580 1.85 5F2 21100 20880 0.57 20700sh 1.57 l 21140 0.95 l 21190 2.02 iKs 21370 21410 0.95 21410 2.86 21740 44.6 21640 48.0 22120 106.9d) 50.2d) sa6 22100 22120 4.67 { 21910 21980sh 48.1 22320 34.6 )FI 22220 4.71 22780 2.23 l 23040sh 2.62 23280sh 4.13 23700 0.99 23580sh 3.5 23580 7.36 (5G, 3G)s 23950 { 24040 2.98 { 23750 4.3 23700 7.19 l23510 6.65 Erbium (4f 11 )

Electronic Er3+(aq)•> Er(NO3) 3 in waterh> ErL3 in 95% EtOHh> Er(thd)3 (gaseous)"l transition•> E(cm-1) E(cm-1) E(M-1 cm-1) E(cm-1) E(M- 1 cm-1) E(cm-1) E(M- 1 cm-1)

4 11s12--+ 4F 15250 15020 0.57 15000sh 0.7 15384 1.6 4 l 15340 2.06 15310 2.36 15527sh 0.9 18250 0.22 18410 1.26 18518sh 1.6 4SJ/l 18350 18500 0.74 18480 1.11 18726 3.8 ! !19120 29.2 ! 2 19150 19160 3.52 19157 25.9d) H1112 19270 52.ld) 4F112 20450 20410 0.93 20491 0.7 20580 2.11 I 20490 2.78 22120 0.41 21980 1.45 4Fs12 22100 { 22270 0.93 { 22220 1.97 4FJ112 22500 22680 0.45 22620 1.60

Thulium ( 4f12 )

3 Electronic Tm +(aq)•> TmCl 3 1in waterh> TmL3 in 95% EtOHb) Tm(thdh (gaseous)') transition• 1 E(cm-1) E(cm-) E(M- 1 cm-1) E(cm-1) E(M-1 cm-1) E(cm-1) E(M- 1 cm-1)

7.0ld) iH,,-+ iH, 12700 12850 0.86 12600 12376 2.8 { 12900 sh 1.35 { 13706 8.8d) 14370sh 0.90 3Fi 14500 14600 2.32 14450 { 14640 2.58 1.0 3F2 15100 15170 0.23 15100 0.26 14792 1.0 21550 21200 2.90 ia. 21550 0.47 { 21276 3.2 21500sh 1.80

•I From ref. ( 18); hl this work; ' 1 from ref. ( I 7); di hypersensitive bands. Transition Met. Chem. 8, 298-304 (1983) Lanthanide chelate of 2-thenoyltrifluoroacetone 303

Magnetic measurements Bailar, H.J. Emeleus, R. S. Nyholm, and A. F. Trotman-Dickenson (Eds.) Comprehensive Inorganic Chemistry, Pergamon, Oxford Magnetic susceptibility measurements were made in an (1973), vol. 4, p. 22. - <3> J. G. Stites, C. N. McCarty and L. L. Quill, atmosphere of nitrogen on a Newport variable-temperature J. Am. Chem. Soc., 70, 3142 (1948). _ <4> S. E. Livingstone and W. A. Gouy balance. The data are listed in Table 4. Zimmermann, Australian J. Chem., 29, 1845 (1976). - <5> G. W. Pope, J. F. Seinbach and W. F. Wagner, J. Inorg. Nuc/. Chem., 20, 304 Visible spectra (1971). -<6> J. Phillips, D. E. Sands and W. F. Wagner, Inorg. Chem., 7, 2295 (1968). - <7> B. N. Figgis and J. Lewis, Technique of Inorganic The visible spectra were obtained at room temperature on a Chemistry, Interscience, 4, 137 (1965). - (Sl J. Selbin, N. Ahmad and Cary 17 spectrophotometer from solutions of the metal che- N. Blacca, Inorg. Chem., JO, 1383 (1971). - <9> J. H. Van Vleck, The lates in 95% ethanol and of the lanthanide nitrates in water. Theory of Electric and Magnetic Susceptibilities, Oxford Univ. Press (1932), Ch. IX. - <10> M. S. Ansari and N. Ahmad, J. Inorg. Nuc/. References Chem., 37, 2099 (1975).

<1> J. Moeller, D. F. Martin, L. C. Thompson, R. Ferrus, G. R. Feistel <11 > J. Zernicke and C. James, J. Am. Chem. Soc., 48, 2827 (1926). - and W. J. Randall, Chem. Rev., 65, 1 (1965). - <2> J. Moeller, in J.C. <12> J. M. Birmingham and G. Wilkinson, J. Am. Chem. Soc., 78, 42

Table 4. Detailed magnetic data•> for the lanthanide complexes (LH = 2-thenoyltrifluoroacetone).

T (K) 1D6Xt,i !Leff T (K) 1Q6 XM fleff T (K) 1Q6 XM fleff

Ce½ · 2H2O Pr½· 2H2O Nd½· 2H2O 98.9 5026 1.99 98.9 11498 3.02 98.9 11806 3.06 127.6 4325 2.10 127.6 9609 3.13 127.6 9731 3.15 156.5 3773 2.17 156.5 8193 3.20 156.5 8190 3.20 183.2 3770 2.22 183.2 7073 3.22 183.2 7224 3.25 215.6 3057 2.30 215.6 6277 3.29 215.6 6341 3.31 244.9 2878 2.37 244.9 5575 3.30 244.9 5745 3.35 275.0 2654 2.42 275.0 5090 3.35 275.0 5169 3.37 304.4 2445 2.44 304.4 4631 3.36 304.4 4738 3.40

Sm½· 2H2O Eu½ · 2H2O Gd½ · 2H2O 98.9 1383 1.04 98.9 6018 2.18 98.9 77838 7.85 112.9 1340 1.10 112.9 5941 2.31 127.6 62613 7.99 127.6 1323 1.16 127.6 5825 2.44 156.5 51931 8.06 141.7 1297 1.21 141.7 5773 2.56 186.1 43591 8.05 156.5 1280 1.26 156.5 5696 2.67 215.6 37439 8.03 171.1 1271 1.32 171.1 5593 2.76 244.9 32849 8.02 186.1 1245 1.36 183.1 5438 2.84 275.0 29147 8.01 200.8 1194 1.38 200.8 5348 2.93 304.4 26378 8.01 215.6 1202 1.44 215.6 5180 2.99 230.1 1194 1.48 230.1 5090 3.06 244.9 1228 1.55 244.9 4858 3.08 259.9 1194 1.58 259.9 4820 3.17 275.0 1185 1.61 275.0 4665 3.20 289.5 1211 1.67 289.5 4613 3.27 304.4 4523 3.32 318.2 4381 3.34 333.2 4317 3.39 348.2 4291 3.46

Tb½· 2H2O Dy½· 2H2O Ho½· 2H2O 98.9 114448 9.51 98.9 136210 10.38 98.9 128155 10.Q7 127.6 89223 9.54 127.6 109008 10.55 127.6 101262 10.17 156.5 72856 9.55 156.5 88853 10.55 156.5 83341 10.21 186.1 60840 9.52 183.1 75620 10.61 183.2 70710 10.26 215.6 54509 9.69 215.6 65023 10.59 215.6 61186 10.27 244.9 47876 9.68 244.9 57335 10.60 244.9 53871 10.27 275.0 42636 9.68 245.0 51115 10.60 275.0 47889 10.27 304.4 38544 9.69 304.4 46233 10.61 304.4 43334 10.27

Er½· 2H2O TmL3 • 2H2O Yb½ · 2H2O 98.9 105253 9.12 98.9 63001 7.06 98.9 20080 3.99 127.4 81941 9.14 127.6 51629 7.26 127.6 16191 4.06 156.5 67974 9.22 156.5 41026 7.17 156.5 13626 4.13 215.6 50660 9.35 183.2 34860 7.15 183.2 11733 4.15 244.9 44703 9.36 215.6 30262 7.22 215.6 10381 4.23 304.4 36323 9.40 244.9 26851 7.25 244.9 9207 4.25 275.0 24096 7.28 275.0 8361 4.29 304.4 21870 7.30 304.4 7615 4.31

' 1xi.t in c.g.s.units 304 M. M. Mostafa and D. X. West Transition Met. Chem. 8, 304-308 (1983)

(1956). - <13J F. Hund, Z. Physik, 33,855 (1925). - 0 4l J. H. Van Vleck Moeller in H.J. Emeleus (Ed.), MTP International Review of Science and A. Frank, Phys. Rev., 34, 1494, 1625 (1929). - osJ B. R. Judd, Inorganic Chemistry Series One, Butterworths, London, 7,275 (1972). Phys. Rev., 127, 750 (1962). - <16l G. S. Ofelt, J. Chem. Phys., 37,511 <21 l S. J. Lyle and M. M. Rahman, Talanta, 10, 1177 (1963). - <22l A. J. (1962). - 07J D. M. Gruen, C. W. De Kock and R. L. McBeth, Adv. Vogel, Textbook of Quantitative Inorganic Analysis, 3rd Edit., p. 443, Chem. Ser., 71, 102 (1967). -

Preparation and Characterization of Divalent Metal Ion Complexes of N-2-picolyl-N' -phenylthiourea

Mohsen M. Mostafa* and Douglas X. West** Department of Chemistry, Illinois State University, Normal, Illinois, 61761, USA

Summary spectral methods. Subsequent reports from this laboratory will involve altering the position of the thiourea function as well as New complexes of J\'.-2-picolyl-N' -phenylthiourea (HPPT) a study of the analogous N-oxides. have been prepared employing a number of different divalent metal ion salts. The resultant Co 11 , Ni 11 , and Cu 11 complexes, which generally involve coordination of HPPT, except for the Results and Discussion Cu11 halides which have a deprotonated ligand, have been All the copper complexes listed in Table 1 are black if undi characterized by partial elemental analysis, molar conductivity luted and the colours listed were obtained by milling these and spectral (i.r., u.v.-vis., and e.s.r.) studies. HPPT is an NN solids with NaBr and/or MgO. All the solids are stable in air bidentate ligand while the deprotonated form serves as an and show little tendency to attract water although they were NNS bridging tridentate ligand. The complexes undergo par maintained in a vacuum desiccator when not in use. Two types tial or total decomposition in the solvents in which they are of complexes have been isolated with Cu11 , [Cu(HPPT)zX2] soluble. The compounds [Cu(HPPT)zX2] have resolved gll fea (X Cl0 , BF or N0 ) and [Cu(PPT)X](H 0) (X Cl or tures in their powder spectra indicating that magnetic dilution = 4 4 3 2 = Br) and repeated attempts to prepare compounds of other has occurred. stoichiometries failed. Complexes of only one stoichiometry were isolated with the perchlorate salts of Co11 and Ni11 , each Introduction having three ligands per metal ion. The solids isolated with the Recently, one of us has reported extensively on the transi halide salts of these two ions have one ligand although a bright tion metal complexes of thiosemicarbazide moieties< 1> while yellow Ni11 which apparently has two ligands per metal ion is the other has been active in the study of the complexes of presently being studied. While the solids are soluble in com substituted pyridine N-oxides<2l. There has been relatively lit mon solvents, their solubility is marked by a colour change tle study of the complexes of 2-substituted pyridine in which an indicating partial or complete decomposition. Also, there is a additional functional group attached to the ring contains a continuous change in the value of their conductivities with sulphur atom<3>, except for thiosemicarbazones(4). Few studies time which again suggests a change in the nature of the com on the corresponding pyridine N-oxides have been reported<5l. plex with dissolution. The values for AM reported in Table 1 Also, the thiourea grouping has been little studied because of were taken immediately after submerging the dip cell. The its relativelti weak coordinating ability to first row transition compounds prepared from the salts of polyatomic anions have metal ions< l_ Therefore, we have embarked on a study of 2- molar conductivities generally consistent with 1 : 2 electrolytes substituted pyridine and pyridine N-oxide ligands in which the while the halide derivatives appear to be non-electrolytes<8>. substituent contains a thiourea centre capable of bonding to The rather high values measured for some of the halides is the metal ions. A further reason for initiating this study is the probably indicative of some dissociation of the complexes. potential of these ligands and/or their metal complexes for Of note is that the ligand is a neutral species in all of the Co11 medicinal use in that they are similar to substances being and Ni 11 solids and the 2 : 1 Cu11 complexes, but is an anion in reported as having significant therapeutic potentia1<7l. the halide complexes of Cu11 and this indicates a difference in In this report we communicate our preparation of some the bonding of the ligand in the two types of complexes. The Co11 , Ni 11 and Cu 11 complexes of N-2-picolyl-N' -phenyl bands most useful in determining the nature of ligand-bonding thiourea (HPPT) and their characterization, primarily by are presented in Table 2 along with the analogous bands for the free ligand. We have included only the complexes pre • On leave from Mansoura University, Mansoura, Egypt. pared from copper(II) perchlorate and chloride as representa • • Author to whom all correspondence should be directed. tive of the two types of ligand bonding.

COMO-TWELVE

INSTITUTE

METAL-ORGANIC

CHEMICAL

CONFERENCE:

AND

Auatrall1

Teamanl1

7005

NATIONAL

Department

AUSTRALIAN

Tea.

ABSTRACTS

0729-2600

Thomaa

DIVISION COORDINATION CONFERENCE ROYAL

Rudi

Hobart EDITOR Chemistry TWELFTH University

ISSN

AND

Tasmania

1984

January

University

22-26

The PROGRAM ~ a

the

53 34

press). in

100

cerium

(in

1845.

and

100

elven

the

ceriUII 29,

display

Ce,

are

100

1983,

the

all

2115.

intensities

1976,

ions

59 Ito

••

while

100

oxidation

that spectrometer 27,

Only

Chem

54 37

63 26

50 21

100

Cl1cm.,

mass

1974,

relative

thenoyltrifluoroacetone

Met.

19 17

bivalent,

100

the

indicating

reduced,

The

52 32 84

35 12 12

Cl:em.,

A1wt.

100

metal-containin&

lanthanides

also

thenoyltrifluoroacetone

32 Eu

65 39

Transition

chelates

100

the

M-2L•2F,

can

major

behaviour

AuaL.

S111

55 35

metals

and

100

metal

Zlmmenn,inn,

quadrivalent.

and

This

72 26 46 Nd

the

100

these

M-L•F,

complexes

W,A,

1.ivingstone,

Yb,

chemistry

can

58 59

100

for

and

a110n1

state.

1.lvingstonc,

Sm,

intensities

SCO•CIIC0CF

S.E.

H 51 18

Ce 20 17

known

100

Eu,

spectra

peaks

and

S.ll.

lanthanide

•

the

- 20·

99 97

extent,

but

100

tundency

and

Relative

mass

show

the

l.ivlngstono

lf;1mcr

with

quadrivalcnt

Das

for

lesser

A.~I.

►

S,ll.

the

Jecreasing

complexes keeping

tervalency,

peaks

much

Table

Ion

TABLE

M-CF

M-L+F

M-L

M-L-CF

1.nF

M-2L+2F LnF z. M-2L•F

M-2L•F-CF

l. llnfrrc11c,1n

fr,

for

is Sm,

and

for

trans

this

excs many

llo,

lanth3n

2033

3nd

has

and

Nd,

µcff

with

three

Dy,

1111,

4 intcnsitios

peaks of

comp

Pll-50

Pr,

this H

pattern

spectr3,

~1-2L+F,

N.S.W. in,licatcs

whcre3s Sm,

last the

the

samarium

Ce,

values m-MeC

strong

Nd,

for

the

11cak pl3ce;

coefficients

La,

the

B-diketones

FLUORINATED

visible

corresponding hypersensitive

indicating

•

state;

Pr,

of The

M-L-CF

similar,

this

only

and taken

(Ln

Ksnsington,

fr3gmentation

SOME

other

~1-L,

p-BrC

lncd ,

h3S

moments,

3 the

extinction

for

ions.

bivalc"t

moments

.zH

fluorinated

bands,

Walas,

obta

occurrence

)

remarkably

M-CF

the

with

complexes

metal

ch~racterized

thu

where

was

The

occurr.:ncll

are

2-thienyl,

South

ions

magnetic the

• the

3queous arc of

reported

m3gnetic

CH~LATES

•.

)

The to

Ne1,J

R •

l.nl') 2

the

absorption

(

The

observed

their

reduced

those

temperature-dependent.

Livingstone•

(LnF

Yb;

for

spectra T11.

complexes,

Ln(RC0•CIICOCF

for

complexes

order:

and

comple~cs

were

arc

fragmented spectra

and

The

the

migration

the

line-like

i.e., peak found

metal

LAtHHANIDE

Tm 2 the

strongly

Yb, obtained.

and

University

chelates

Stanley

prepared

Er,

and

visible

•

Sm,

those arc

are

usual

lanthanide

been

metal.

Er,

fluorine

and

lanthanide•

Ho,

M-JL•2F,

The

l:u, spectra

been

the

for

ion

the

transition than

llo,

•

dccrcaso

have

and that Dy,

SPECTRA

four

p-~1ec

Hamer lanthanide ,

Cl:errri.stry,

for

mass

chel3tes have Nd,

complexes

)

lb,

M. p,·aks

4 and display

greater shows

The The 1t

t",ASS

spectra these reported

Ph which

Gd, other molecular compounds.

the

not

•

L-DIKETONES

THE

Andrew

Scliool

ide

for the itions

that europium ls Eu, times the

aass and peaks been

determined A or o-MeC

M-2L•F-CF GLOSSARY

Conventions of Mass Spectrometric Notation

Throughout this thesis the symbolism and conventions adopted are 58 those of MacDonald and Shannon, viz.:

(1) Electron shifts are indicated by curved arrows with "full" (two-electron shift) and "halved" (one-electron shift) arrowheads.

(2) Met= metal (Met is used to avoid confusion with both the abbreviation for. the methyl group, Me, and the symbol for the molecular ion, M.

(3) The terms odd- and even-electron ion and the symbols+ and +• refer to that part of the ion other than the non-bonding electrons of the metal atom.

(4) M = molecular ion (whether this is an odd- or even-electron +• molecular ion is left undefined); M = odd-electron molecular ion; M+ = even-electron molecular ion.

(5) M-76 eta. indicates an ion of 76 a.m.u. less than the molecular ion, but not necessarily formed by a single-step loss of a neutral fragment or fragments of total 76 a.m.u.

(6) Similarly, M-CF 3 eta. indicates an ion at m/e corresponding to loss of a CF 3 group from the molecular ion but not necessarily formed by a single-step loss of a neutral fragment.

(7) Dative bonds are omitted in structural formulae to avoid possible confusion between the symbol for dative bonds (arrows) and the symbol for "electron-shifts" (curved arrows). 164

ABBREVIATIONS

BPB 4,4,4-trifluoro-l-(X'-bromophenyl)-1,3-butanedione, X = 2, 3 or 4 p-BPB 4,4,4-trifluoro-1-(4'-bromophenyl)-1,3-butanedione

DMH 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione

Ln any lanthanide (including yttrium)

M molecular ion in mass spectra

Met any metal, used to avoid confusion with the molecular ion, M.

MPB 4,4,4-trifluoro-1-(X'-methylphenyl)-1,3-butanedione, X = 2, 3 or 4 o-MPB 4,4,4-trifluoro-l-(2'-methylphenyl)-1,3-butanedione m-MPB 4,4,4-trifluoro-1-(3'-methylphenyl)-l,3-butanedione

TTB 4,4,4-trifluoro-l-(2'-thienyl)-1,3-butanedione 165

REFERENCES

1. L.A. Aslanov, E.F. Korytyni, and M.A. Porai-Koshits,

Zh. Strukt. Khim., 12, 661 (1971).

2. L.A. Aslanov, M.A. Porai-Koshits, and M.O. Dekaprilevich,

Zh. Strukt. Khim., 12, 470 (1971).

3. G.M. Bancroft, C. Reichert, and J.B. Westmore,

Inorg. Criem., J_, 870 (1968).

4. G.M. Bancroft, C. Reichert, J.B. Westmore, and H.D. Gesser,

Inorg. Criem., ~, 474 (1969).

5. R. Belcher, J. Majer, R. Perry, and W.I. Stephen,

J. Inorg. NuoZ. Chem., 31, 471 (1969).

6. M.J. Bennett, F.A. Cotton, P. Legzdins and S.J. Lippard,

Inorg. Criem., J_, 1770 (1968).

7. J.M. Birmingham and G. Wilkinson,

J. Am. Chem. Soo., 78, 42 (1956).

8. W.R. Busing and H.A. Levy, ORFLS, Oak Ridge National Laboratory (1962).

9. W.R. Busing, K.O. Martin and H.A. Levy, ORFFE, Oak Ridge National

Laboratory (1964).

10. W.T. Carnall and P.R. Fields, "Lanthanide/Actinide Chemistry"

Advances in Chemistry Series, No. 71, American Chemical

Society, Washington, D.C., pp 86-101 (1967).

11. W.T. Carnall, P.R. Fields, and K. Rajnak,

J. Criem. Phys., 49, 4424 (1968).

12. W.T. Carnall, P.R. Fields, and K. Rajnak,

J. Chem. Phys., 49, 4443 (1968).

13. W.T. Carnall, P.R. Fields, and K. Rajnak,

J. Chem. Phys., 49, 4447 (1968). 166

14. W.T. Carnall, P.R. Fields, and K. Rajnak,

J. Chem. Phys., 49, 4450 (1968).

15. O. Cea Olivares, J. Gomez-Lara, and E. Cortes,

J. Inorg. Nu.cl. Chem., 42, 1530 (1980).

16. A.L. Clobes, M.L. Morris, and R.D. Koob,

J. Am. Chem. Soa.,91, 3087 (1969). ·

17. A.L. Clobes, M.L. Morris, and R.D. Koob,

Org. Mass Speatrom., i, 633 (1971).

18. F.A. Cotton and P. Legzdins,

Inorg. Chem., J_, 1777 (1968).

19. D.C. Craig, M. Das, S.E. Livingstone, and N.C. Stephenson,

Cryst. Struat. Comm., l, 283 (1974).

20. J.A. Cunningham, D.E. Sands, and W.F. Wagner,

Inorg. Chem.,.§., 499 (1967).

21. J.A. Cunningham, D.E. Sands, W.F. Wagner and M.F. Richardson,

Inorg. Chem.,~' 22 (1969).

22. M. Das, Ph.D. Thesis, University of New South Wales (1974).

23. M. Das and S.E. Livingstone,

Org. Mass Speatrom., 2_, 781 (1974).

24. M. Das and S.E. Livingstone,

Austral. J. Chem., 28, 1513 (1975).

25. M. Das and S.E. Livingstone,

Inorg. Chim. Aata, 14, 267 (1975).

26. M. Das and S.E. Livingstone,

J. Inorg. Nual. Chem., 43, 3412 (1981).

27. N.K. Davidenko, A.G. Goryushko, and K.B. Yatsimirskii,

Stroenic, Svoistva I Primenenic 8-dikenatov Metallov

[Mater. Vses. Semin], 3rd, pp. 58-75 (1977, Pub. 1978),

(Chem. Abstr. 91:150411c). 167

28. K.J. Eisenstraut and R.E. Seivers,

J. Am. Chem. Soa., !I_, 5254 (1965).

29. B.N. Figgis and J. Lewis, "Technique of Inorganic Chemistry",

H.B. Jonassen and A. Weisberger ed., Interscience, New York,

pp. 146-9, 199-203, 240-43 (1965).

30. J.J. Fritz, T. Grenthe, P.E. Field, and W.C. Fernelius,

J. Am. Chem. Soa., 82, 6199 (1960).

31. I.K. Gregor, K.R. Jennings, and D.K. Shan Sharma,

Org. Mass Speatrom., 12, 93 (1977).

32. D.M. Gruen, C.W. DeKock, and R.L. McBeth,

"Lanthanide/Actinide Chemistry", Advances in Chemistry

Series, No. 71, American Chemical Society, Washington, D.C.,

p. 102 (1967).

33. F. Halverson, J.S. Brinen, and J.R. Leto,

J. Chem. Phys., 40, 2790 (1964).

34. D.E. Henrie, R.L. Fellows, and G.R. Choppin,

Coard. Chem. Rev., 18, 199 (1976).

35. R.K.Y. Ho and S.E. Livingstone,

Austral. J. Chem., 21, 1781 (1968).

36. J.L. Hoard and J.L. Silverton,

Inorg. Chem., I, 235 (1963).

37. F. Hund, Z. Physik, 21_, 855 (1925).

38. J.A. Ibers and W.C. Hamilton (eds.), International Tables for

X-Ray Crystallography, Volume IV, Kynock Press, Birmingham

(1974).

39. A.L. Il'inskii, L.A. Aslanov, V.I. Ivanov, A.D. Khalivov, and

0.M. Petrukhin, Zh. Strukt. Khim., 10, 285 (1967). 168

40. T. Isobe and S. Misumi,

BuU: Chem. Soc. Japan, 47, 281 (1974).

41. C.K. Johnson, ORTEP, Oak Ridge National Laboratory (1965).

42. C.K. J,rgensen and B.R. Judd,

MoZ. Phys.,~, 281 (1964).

43. B.R. Judd,

Phys. Rev., 127, 750 (1962).

44. D.G. Karraker,

Inorg. Chem., J_, 473 (1968).

45. D.G. Karraker,

Inorg. Chem., 6, 1863 (1967).

46. D.L. Kepert, "Inorganic Stereochemistry", Springer-Verlag,

Berlin (1982).

47. V.S. Khomenko, A.A. Bondareva, and V.P. Suboch, Vestsi,

Akad. Navuk BSSR, Ser. Khim. Navuk (1), 36 (1978)

(Chem. Abstr. 89:35698y).

48. V.S. Khomenko, T.A. Rasshininia, Zh. Prikl. Spectrosk.

29, 129 (1978) (Chem. Abstr. 89:225515j).

49. V.S. Khomenko, T.A. Rasshininia, and V.M. Suboch, Vestsi,

Akad. Navuk BSSR, Ser. Khim. Navuk (3), 36 (1979)

(Chem. Abstr. 91:100799q).

SO. V.S. Khomenko, T.A. Rasshininia, V.M. Suboch, and N.E. Akimova,

Vestsi, Akad. Navuk BSSR, Ser. Khim. Navuk (4), 54 (1981)

(Chem. Abstr. 95:180007a).

51. L.I. Kononenko, M.A. Tishchenko, and U.N. Drobyazko,

Zh. Anal. Khim., 26, 729 (1971).

52. B.R. Kowalski, T.L. Isenhour, and R.E. Sievers,

Anal. Chem., 41, 998 (1969). 169

53. W.F. Krupke and J.B. Grueber,

Phys. Rev., 139, A2008 (1965).

54. M.D. Lacey and J.S. Shannon,

Org. Mass Speatrom., i, 931 (1972).

55. S.J. Lippard and B.J. Russ,

Incrg. CMm., J_, 1686 (1968).

56. S.E. Livingstone and W.A. Zimmermann,

Austral. J. Chem., 29, 1845 (1976).

57. S.J. Lyle and M.M. Rahman,

Talanta, 10, 1177 (1963).

58. C.G. Macdonald and J.S. Shannon,

Austral. J. Chem., 19, 1545 (1966).

59. P. Main, M.M. Woolson, L. Lessinger, G. Germain, and J.P. Declercq,

MULTAN80, University of New York (1980).

60. R.C. Mehrotra, R. Bohra and D.P. Gaur, "Metal B-diketonates and

Allied Derivatives", Academic Press Inc., London (1978).

61. P.C. Mehta and S.P. Tandon,

J. Chem. Phys., 53, 114 (1973).

62. L.R. Melby, N.J. Rose, E. Abramson, and J.C. Caris,

J. Am. Chem. Soa., 86, 5117 (1964).

63. S.N. Misra,

Indian J. Chem., 19, 1135 (1980).

64. S.N. Misra,

Indian J. Chem., 20, 187 (1981).

65. S.N. Misra, J. Indian Chem. Soa., -22., 99 (1982). 170

66. T. Moeller, "Complexes of the Lanthanides", in MTP International

Review of Science, "Lanthanides and Actinides", Inorganic

Chemistry, Series One, Volume 7, K.W. Bagnall ed.,

Butterworths London, pp. 279-80 (1972).

67. T. Moeller, D.F. Martin, L.C. Thompson, R. Ferrus, G.R. Feistel,

and W.J. Randall,

Chem. Rev., 65, 1 (1965).

68. R.T. Morrison and R.N. Boyd, "Organic Chemistry", Allyn and Bacon,

2nd ed., Boston, pp. 934-936 (1971).

69. L.N. Mulay, "Techniques of Chemistry, Vol. 1. Physical Methods

of Chemistry, Part IV", A. Weissberger and B.W. Rossiter, eds.

Wiley-Interscience, New York, pp. 448-53 (1972).

70. C.J. O'Connor,

f>rog. Inorg. Chem.,~' 203 (1982).

71. G.S. Ofelt,

J. Chem. Phys., 37, 511 (1962).

72. J.D. Park, H.A. Brown and J.R. Lachen,

'J. Am. Chem. Soa., 11, 4753 (1953).

73. T. Phillips, D.E. Sands, and W.F. Wagner,

Inorg. Chem.,]_, 2295 (1968).

74. C. Reichert, G.M. Bancroft, and J.B. Westmore,

Canad. J. Chem., 48, 1362 (1970).

75. C. Reichert and J.B. Westmore,

Inorg. Chem.,~' 1012 (1969).

76. C. Reichert, J.B. Westmore, and H.D. Gesser,

Chem. Commun., 782 (1967).

77. T.H. Risby, P.C. Jurs, F.W. Lampe, and A.L. Yergey,

Anal. Chem., 46, 161 (1974). 171

78. T.H. Risby, P.C. Jurs, F.W. Lampe, and A.L. Yergey,

Ana~. Chem., 46, 726 (1974).

79. V. Schomaker, J. Waser, R.E. Marsh and G. Bergman,

Aata Cryst., 12, 600 (1959).

80. J. Selbin, N. Ahmad, and N. Bhacca,

Inorg. Chem., 10, 1383 (1971).

81. R.E. Sievers, K.J. Eisentraut, and C.S. Springer, Jr.,

"Lanthanide/Actinide Chemistry", Advances in Chenµ.stry

Series, No. 71, American Chemical Society, Washington, D.C.,

pp. 141-54 (1967).

82. J.G. Stites, C.N. McCarty, and L.L. Quill,

J. Am. Chem. Boa., 70, 3142 (1948).

83. V.P. Suboch, V.S. Khomenko, and T.A. Rasshinina, Vestsi,

Ale.ad. Navuk BSSR, Ser. Khim. Navuk (1), 96 (1981)

(Chem. Abstr. 94:184777d).

84. D.R. Templeton and C.H. Dauben,

J. Am. Chem. Boa., !.2.., 5237 (1954).

85. J.H. Van Vleck, "The Theory of Electric and Magnetic Susceptibilities",

Oxford Univ. Press, Ch. IX (1932).

86. J.H. Van Vleck and A. Frank,

Phys. Rev., 34, 1494 (1929).

87. H.S. Verma, S.C. Rastogi, R.C. Saxena, and K.C. Mathur,

Indian J. Chem., 20, 188 (1981).

88. A.I. Vogel, "A Textbook of Quantitative Inorganic Analysis",

Longman, London, 3rd Edn., pp. 443-444 (1961).

89. J.G. White,

Inorg. Chim. Aata, 16, 159 (1976). 172

90. B.G. Wybourne, "Spectroscopic Properties of the Rare Earths",

Joh~ Wiley & Sons, New York (1965).

91. K.B. Yatsimirskii and N.K. Davidenko,

Coord. Chem. Rev., 'l:]_, 223 (1979).

92. A. Zalkin, D.R. Templeton, and D.G. Karraker,

Inorg. Chem.,~, 2680 (1969).