SOME STUDIES ON CYCLOPENTADIFNYL AND CARBONYL COMPLEXES OF TRANSITION METALS. A Thesis submitted by JON ARMISTICE McCLEVERTY, B.Sc. for the Degree of Doctor of Philosophy of the University of London. Royal College of Science. May 1963. This Thesis I dedicate to DIANNE. Her love and understanding is a continual inspiration. kit CHAPTER II ic-CYCLOPENTADIENYL METAL HYDRIDES THE DI-n-CYCLOPENTADIENYL HYDRIDES OF TANTALUM MOLYBDENUM. AND TUNGSTEN. The hydride complexes are prepared in high yields by the inter- action of the anhydrous metal chlorides (Noel" 1C16, or TaC15) with a solution of sodium cyclopentadienide in tetrahydrofuran containing an excess of sodium borohydride. Without addition of borohydride to the sodium cyclopentadienide solution only low yields of the hydrides can be obtained since the hydriue ion required must come from the solvent or from traces of excess of cyclopentadiene or cyclopentene present in the reaction mixture. The tantalum hydride, (n-C5H5)2TaH3, is a white crystalline compound which is sensitive to air; the molybdenum and tungsten hydrides, (n-05H5)2MH2, form yellow crystals, the former being more sensitive to air than the latter, which can be handled briefly in air. The tantalum compound is sparingly soluble in light petroleum but it is moderately soluble in benzene; the other hydrides are soluble in light petroleum as well as in other common solvents. Solutions of all three compounds decompose rapidly wren exposed to air. The compounds are soluble in halogenated solvents and in carbon disulphide but react with them quite rapidly, the order of reactivity being Ta Mo ACKNOWLEDGMENTS I would like to express my deep gratitude to Professor G. Wilkinson for his constant encouragement, patience, and guidance during his supervision of this work. I am very grateful to Dr. D. F. Evans, Dr, R. Mason, and particularly Ir. L. Pratt, for their invaluable assistance. I am indebted to my colleagues and friends in the lab. for their continual help and advice, both academic and otherwise. I would also like to thank my mother for helping to ensure that I got as far as this. My thanks are due to Miss C. M. Ross for her care in typing this thesis. The award of a scholarship from the Carnegie Trust for the Universities of Scotland, for the period 1960-3963, is gratefully acknowledged. ABSTRACT The di-I-cyclopentadienyl hydrides of molybdenum, tungsten and tantalum have been prepared. High-resolution proton magnetic resonance and infrared spectra of these compounds and of the trihydride cations of molybdenum and tungsten have been measured. For the trihydride species of tungsten and tantalum the patterns of the high-field lines show that there are two equivalent hydrogen atoms in an A2B grouping. This observation is discussed with reference to the base character and to the molecular configuration of the di-n-cyclopentadienyl metal hydrides. High-resolution proton magnetic resonance spectra of hydrido, methyl and ethyl derivatives of transition-metal carbonyl and %-cyclopentadienyl carbonyl derivatives have been measured, and the data compared with those for non-transition-metal compounds. Infrared spectra of some hydrides and corresponding deuterides are given. An improved preparation of Re2(CO)to is given and the new complexes 7c-05H5Ru(C0)2X (X = H, D, I, CH3 and C2H5) are described. The preparation of some propionyl derivatives of the type II-05H5M(CO)nC0C2H5 (M = Mb, W, Fe, Ru; n = 2, 3) is described. A novel alkyl transfer reaction in 7c-05H5MO(Q0)3C2H51 where the ethyl group migrates from the metal to the cyclopentadienyl ring, is also described. Reaction of n-05H5Rh(C0)2 with CF3I, C2F5I and C3F7I affords the compounds n-05H5Rh(CO)RfI (Rf = perfluoroalkyl radical). Their high-resolution fluorine magnetic resonance spectra are discussed. TABLE OF CONTENTS Chapter Page I Introduction 1 II The Cyclopentadienyl Hydrides 12 III Transition—metal Alkyls and Related Derivatives 32 IV Rhodium Perfluoroalkyl Compounds 50 V Experimental 61 References 79 CHAPTERI INTRODUCTION Metal hydrides can be classified broadly into four main groups. These are: (a) salt-like hydrides of which LiH and CaH, are examples; (b) covalent transition-metal hydrides such as HMn(C0)5, (7C-0 5H5 )2WH2, and (Et3P)2PtHC1; (c) complex hydrides like LiA1H4 and NaBH4; and (d) other hydrides. These include the polymeric BeH2 and MgH2, CuH, the transition-metal binary hydrides such as PrH3 and UH3 and the non-stoichiometric compounds like TiE1 .7 and the "Weichfelder Hydrides". The hydrides H2Fe(C0)3 and HCo(C0)41'2 were discovered in 1931 but studies in this field have greatly intensified in the last four years. Now a large number of transition metals, complexed with a variety of ligands, have been shown to form covalent molecular hydrides and Table 1 displays a selection of these. At first it seemed that strong-field ligands such as '3P, CO, CN, or 7-05H5 were necessary to stabiliso the metal-hydrogen bond but recently the existence of hydridic species in systems containing ethylenediamine, ammonia, pyridine or dimethylglyoxime has been 6486 demonstrated. Unusual compounds of rhenium (and technetium), the "rhenohydrides" or "rhenides", have been prepared and their 5051 hydridic nature claimed. They may be analogous to the complex 2. hydrides of group (c) but they are difficult to prepare, purify, and characterise. PREPARATION Transition-metal hydrides can be prepared in a variety of ways. These include: (1) acidification of sodium metal carbonylates, e.g. H3PO4 Re2(C0)10 --> NaRe(C0)5 HRe(C0)5 ,. T.H.F. HC1 t-05H5W(C0)3Na n-05H5W(C0)3H, H2O H3PO4 NaV(C0)5(V3P) mr(co)5(140, (2) sodium borohydride or lithium aluminium hydride reduction of metal halides, e.g. NaBH4 n-05H5Ru(C0)2I > n-05H5Ru(C0)2H, T.H.F. NaBH4. (03P)21An(NO)2Br > (4v3 P)2Mn(NO)2H, T.H.F. LiA1H4 (0'31))3IrliC12 (03P)3IrH3, Et20 NaBH4 [Rh(en)2C12] + [Rh(en)2H2]+9 Et0H (3) by treatment of phosphine or arsine complexes with hypophosphorous acid, e.g. H(H2P02) (Et20As)3RhC13 3 (Et 20AS )3 RhEC12 3 (4)by treatment of phosphine or arsine complexes with hydrazine hydrate in aqueous solution or aqueous ammonia, e.g. trans-(Et3P)2PtC1, N2H trans-(Et3P)2PtHC1, - H 20 (5) by treatment of phosphine or arsine complexes with KOH in ethanol or a polyalooholy e.g. Bt 20 „ KOH (NH4)20sC16 5 (Et2OP)30sC13 (Et20)30s(CO)HC1, • EtoH KOH (0'3P)3RuC13 (V3P)3Ru(CO)HC1, MeOCH2OH (6) by direct synthesis from hydrogen and either the pure, finely divided metal or metal sulphides, e.g. 250 atm. Co + 4C0 2H2 HCo(CO), 180° (7) by sodium borohydride or sodium amalgam reduction of complex metal cyanides in aqueous or ethanolic solution, e.g. 2+ Na/Hg Co + CN > (HCo(CN)03- 1 H2O (8) by protonation in very strong acids, e.g. H2SO4 Fe(C0)5 HFe(C0)5+, BF3,H20 I-05H5W(C0)3H it-05H5W(C0)3H24-1 CF3 COOH HPF6 + (,t-05115)2MoH2 (1-05115)2MoH3 9 H2O HPF6 %-05H5FeMn(C0)7 %-05H5FeMn(C0)7e. H2O 4. TABLE 1 Some Transition-metal Hydrides M.p. i J, Compound Colour 7- H liEl References oc ; c. p.s. cm -05H5)2TiBH4 violet para 1942 55 Ti" 7t-05H5Cr(C0)3H yellow 10 15.46 19,15,18, 87. H2Cr(c0)5 white 9,21,22, 42,53,70. C6H6Cr(C0)3114- yellow soln. 13.55 77 7t-05H5Mo(C0)3H pale yellow 54 15.52 1790 14,19,18, 87. (g-05H5)2MoH2 pale yellow 183-185 18.76 1847 32,69 (n-05R5)2MoH3+ white 16.08 1915 52,69,87 [Mo(C0)6(OH)3H3] yellow 40,41 [n-05H5NO(C0)3]2H+ red brown 30.99 77 soln. ic-05H5W(C0)3H pale yellow 69 17.33 37.7 1845 14,18,19, 87. 7c-05H5W(C0)3H2+ yellow soln. 11.93 77 (n-05H5),WH2 yellow 163-165 22.28 73.2 1896 32,69 (7c-05H5)2WH3+ white 16.08 47.8 1943 52,69,87 16.44 [(I-C15115)jiMo(C0)6De red brown 32.88 77 soln. HMn(00)5 c'less -25 17.50 1728 8,28,29, 44,45. HMn(C0)4(P) yellow 138 1790 82 HMn(N0)2(031))2 yellow 153-154 26.8 32.0 83 H[Mn(C0)4]2P(2 yellow 154-155 84 U2Mn2(C0)9 dark red para 71 06R9Mh(C0)3H orange yellow 88 Mp.. Colour J MH Y References Compound °C c.p.s. cm-1 HTc(C0)5 c'less soln. 79. K2TcH8 white 51. HRe(C0)5 c'less soln. ca. 100 15.66 1820 7,37,38, 87,78. K2ReH8 white 20.05 1846 36,50,51. (it—05H5)2ReH lemon yellow 161-162 22.80 2030 12,26. (7t—05H5)2ReH2+ white 22.90 2055 12,26,87. (933P)3R0H3 red 155 dia. 2000 65. (0'313)4Re113 yellow 147 dia. 2050 66. HaFe(C0)4 yellow —70 21.10 11,17,33. HFe3(C0)11 cherry red 24.90 11,17,33. H2Fe3(C0)12 cherry red '24.90 11,17,33. n—05H5Fe(C0)21-1 yellow liq. —10 21.91 1835 32,87. (n—C5H5)2FeH pale green 11.2 46,31. HFe(C0)54. green soln. 18.15 77. + liFe(C0)403P yellow soln. 17.75 35.31 77. HFe(C0)3(0'313)2+ yellow soln. 18.11 77. En—05H5FeMn(C0)7W orange 38.0 1760 77. [C21-14(Et2P)2]2FeHC1 red 155-156 43.60 1840 48,59. [o—C6H4(Et2P)212FeHC1 red 221 40.50 1870 48,59. [o—C6H4(Et2P)2]2FeH2 c'less 22.9 1726 48,59.