Safety Moment TYLER LAB GROUP MEETING
1 Safety Moment TYLER LAB GROUP MEETING
2 Metal Hydrides: Benchtop vs. Box Hydride = :H- Hydrides are powerful Lewis bases and reducing agent ◦ Exothermically form H2 (this should scare you) ◦ Heating leads to faster reactivity ◦ H evolution leads to rapid increase in pressure2 ◦ Uncontrolled reactions easily cause runaway exotherm, class D fire, explosion, and death/unemployment LiAlH is the #1 chemical cause of fatality in chemical4 industry
3 Metal Hydrides: “I want to commit the murder I was imprisoned for†.”
LiAlH4 ◦ Insanely irritating (serious safety hazard) ◦ Extremely moisture sensitive (don’t leave out for >2 minutes) ◦ Ethereal mixtures are pyrophoric! DiBuAl-H ◦ Pyrophoric – it will explode upon exposure to oxygen
NaEt3BH ◦ Pyrophoric in solution LiH and NaH ◦ Can be handled on the benchtop (not >2 minutes) ◦ Parrafin oil dispersions much safer KH ◦ Pyrophoric if not in a dispersion ◦ Handle with extreme care!
† Sirius Black, Harry Potter and the Prisoner of Azkaban 4 Metal Hydrides: “I want to commit the murder I was imprisoned for†.”
CaH2 ◦ Very safe to handle on the benchtop Pt-H, Pd-H, Ni-H ◦ All very pyrophoric
NaBH4 ◦ Very safe in general Other hydrides ◦ Treat as pyrophoric ◦ Transition metal hydrides vary in hydridic strength ◦ General rule of thumb: if it does hydrogenations, it is probably pyrophoric ◦ If they’re in organics of any kind, they are probably pyrophoric
† Sirius Black, Harry Potter and the Prisoner of Azkaban 5 Organometallic Chemistry BASIC PRINCIPLES, APPLICATIONS, AND A FEW CASE STUDIES
KENDALL, A. J.; TYLER, D. R. LAB GROUP MEETING; 2015/10/14 In Chemiae Veritas: Outline Existential Motivation History of organometallics Fundamental principles of: ◦ 18 e- rule ◦ Crystal field theory ◦ Molecular orbital theory ◦ Metal-carbon bonding Applications to catalysis ◦ Fundamental mechanisms ◦ Case studies
7 What’s the big deal? Principles of organic chemistry Principles of inorganic chemistry Oh, East is East and West is West, and never the twain shall meet, Till Earth and Sky stand presently at God's great Judgment Seat; But there is neither East nor West, Border, nor Breed, nor Birth, When two strong men stand face to face, though they come from the ends of the earth!
-Excerpt from: The Ballad of East and West by Rudyard Kipling, 1889
8 I. History of Organometallic Chemistry The first complexes (1760-1827): ◦ Cadet (1760) ◦ First O/M
◦ Zeise (1827) ◦ First π-complex
Seyferth, D. Organometallics 2001, 20, 1488–1498. Zeise, W. C. Annalen der Physik und Chemie 1831, 97, 497. 9 I. History of Organometallic Chemistry The first complexes (1849-1864) ◦ Frankland (1849-1860) ◦ Air-sensitive O/M
“When (Et2Zn is) dropped into oxygen, however, it bursts into brilliant white flame, attended with slight explosion.” - E. Frankland, 1864
E. Frankland, Prof. and B. F. Duppa, Esq. J. Chem. Soc., 1864, 17, 29-36. 10 I. History of Organometallic Chemistry Main group advances ◦ Friedel and Crafts (1863) ◦ Organosilanes
◦ Schützenberger (1868) ◦ First metal-carbonyls
◦ Mond (1890) ◦ First binary metal-carbonyls
Organosilicon Chemistry S. Pawlenko Walter de Gruyter, New York, 1986. Wisniak, J. Educación Química 2015, 26, 57-65. 11 Liptrot, G. F. (1983). Modern Inorganic Chemistry (4th ed.). Unwin Hyman. p. 386. I. History of Organometallic Chemistry Main group advances ◦ Friedel and Crafts (1863) ◦ Organosilanes
◦ Schützenberger (1868) ◦ First metal-carbonyls
◦ Mond (1890) ◦ First binary metal-carbonyls
Organosilicon Chemistry S. Pawlenko Walter de Gruyter, New York, 1986. Wisniak, J. Educación Química 2015, 26, 57-65. 12 Liptrot, G. F. (1983). Modern Inorganic Chemistry (4th ed.). Unwin Hyman. p. 386. I. History of Organometallic Chemistry Where is organic chemistry during all of this? ◦ Sir. William H. Perkin discovers mauveine by accident ◦ Attempting to make Quinine
Hubner, K. Chemie in unserer Zeit. 2006, 40, 274–275. 13 I. History of Organometallic Chemistry Where is organic chemistry during all of this? ◦ Sir. William H. Perkin discovers mauveine by accident ◦ Attempting to make Quinine ◦ Considered the first chemical industry “Mauveine”
Hubner, K. Chemie in unserer Zeit. 2006, 40, 274–275. 14 I. History of Organometallic Chemistry Where is organic chemistry during all of this? ◦ Sir. William H. Perkin discovers mauveine by accident ◦ Attempting to make Quinine ◦ Considered the first chemical industry “Mauveine”
Hubner, K. Chemie in unserer Zeit. 2006, 40, 274–275. 15 I. History of Organometallic Chemistry Alfred Werner ◦ The father of coordination chemistry
Nobel Prize for Chemistry (1913) Alfred Werner c.a. 1900 ◦ First Nobel Prize for inorganic chemistry ◦ ‘‘in recognition of his work on the linkage of atoms in molecules by which he has thrown new light on earlier investigations and opened up new fields of research especially in inorganic chemistry’’ Kauffman, G. B. Bull. Hist. Chem. 1997, 20, 50-59. Constable, E. C. and Housecroft , C. E. Chem. Soc. Rev., 2013, 42, 1429-1439 16 I. History of Organometallic Chemistry Alfred Werner ◦ The father of coordination chemistry
Listen, old man; take my advice. Give me the cobalt in a thrice. Though Hell and Devil say me nay, I shall resolve cobalt today Nobel Prize-Student Christmasfor Chemistry Play “Rotating and(1913) Resolving,” 1911 Alfred Werner c.a. 1900 ◦ First Nobel Prize for inorganic chemistry ◦ ‘‘in recognition of his work on the linkage of atoms in molecules by which he has thrown new light on earlier investigations and opened up new fields of research especially in inorganic chemistry’’ Kauffman, G. B. Bull. Hist. Chem. 1997, 20, 50-59. Constable, E. C. and Housecroft , C. E. Chem. Soc. Rev., 2013, 42, 1429-1439 17 I. History of Organometallic Chemistry Early 20th century seminal developments ◦ Barbier (1899) ◦ First “coupling” reaction ◦ Grignard (1900) ◦ Nobel Prize 1912 ◦ Pope (1909) ◦ First metal-alkyl complex ◦ Hein (1919) ◦ First “sandwich” complex ◦ Reilhen (1930) ◦ First diene-complex
◦ Hieber (1931) Barbier, P. Compt. Rend. 1899, 128, 110. Grignard, V. Compt. Rend. 1900, 130, 1322–1325. ◦ First hydride complex Pope, W. J.; Peachey, S. J. J. Chem. Soc, Trans. 1909, 95, 571. Hein, F. Berichte Deut. Chem. Gesellschaft, 1919, 52, 195 – 196. Organometallic Chemistry and Catalysis Didier Astruc, Heidelberg, 2007. 18 I. History of Organometallic Chemistry Early 20th century catalysis ◦ Sabatier and Senderens (19011) ◦ Heterogenous Ni catalysis ◦ Nobel Prize 1912
◦ Fischer and Tropsch (1922) ◦ Heterogenous Co catalysis
◦ Roelen (1938) ◦ Homogenous hydroformylation
◦ Reppe (1948) ◦ Homogenous cyclo-oligomerization
◦ Ziegler-Natta (1955) ◦ Homogenous stereo-regular polymerization ◦ Nobel Prize 1963
H. Schulz, Advance Catalysis, Volume 186, 3-12. Cornils, B.; Herrmann, W. A.; Rasch, M. Angew. Chem. Int. Ed. 1994, 33, 2144–2163. 19 Neue Entwicklungen auf dem Gebiet der Chemie des Acetylen und Kohlenoxyds. Springer Berlin, Göttingen, Heidelberg. 1949. I. History of Organometallic Chemistry Ferrocene ◦ Kealy and Pauson (1951) ◦ bis σ-Fe complex ◦ “10 electron” ◦ E. O. Fischer, G. Wilkinson, and R. B. Woodward ◦ Properly I.D. sandwich complex ◦ No net dipole and single C-H stretch by IR ◦ Aromatic characteristics ◦ Nobel Prize 1973 (E. O. Fischer and G. Wilkinson)
T. J. Kealy, P. L. Pauson Nature 1951, 168, 1039. Zydowsky, T. The Chemical Intelligencer, Springer-Verlag, New York, 2000. 20 “The noticeHistory in the Times of of Organometallic the award of this year’s Chemistry Nobel Prize in Chemistry leaves me no choice but to letFerrocene you know, most respectfully, that you have – ◦inadvertently,Kealy and I am Pauson sure – committed(1951) a grave injustice…◦ bis Indeed,σ-Fe whencomplex I, as a gesture to a friend and junior colleague◦ “10 electron” interested in organometallic chemistry, invited◦ E. O.Professor Fischer, Wilkinson G. Wilkinson, to join me and and my colleaguesR. inB. the Woodward simple experiments which verified my structural proposal, his reaction to my views was close ◦ Properly I.D. sandwich complex to derision… But in the event, he had second thoughts ◦ No net dipole and single C-H stretch aboutby his IR initial scoffing view to my structural proposal and its consequences, and altogether we ◦ Nobel Prize 1973 (E. O. Fischer and publishedG. the Wilkinson) initial seminal communication that was written by me.” -T.R. J. B. Kealy, Woodward P. L. Pauson to theNature Nobel 1951 Committee,, 168, 1039. 1973 Zydowsky, T. The Chemical Intelligencer, Springer-Verlag, New York, 2000. 21 I. History of Organometallic Chemistry Where is organic chemistry these days? ◦ Mechanistic understanding ◦ Ingold discovered SN2 and SN1 mechanisms (1934) ◦ Natural products ◦ Robinson ◦ Tropinone (1917) ◦ R. B. Woodward ◦ Quinine (1944) ◦ Cholesterol (1952) ◦ Cortisone (1951) Vitamin B12 ◦ Strychnine (1954) ◦ Lysergic acid (1956) ◦ Reserpine (1958) ◦ Chlorophyll (1960) ◦ Vitamin B12 (1972) ◦ Nobel Prize (1965) Ingold, Christopher K. Chem. Rev. 1934, 15, 238–274. Organometallic Chemistry and Catalysis Didier Astruc, Heidelberg, 2007 22 In Chemiae Veritas: Outline Existential Motivation History of organometallics Fundamental principles of: ◦ 18 e- rule ◦ Crystal field theory ◦ Ligand field theory ◦ Metal-carbon bonding Applications to catalysis ◦ Fundamental mechanisms ◦ Case studies
23 II. Fundamental Principles of Organometallics
Ligands ◦ L-type
◦ X-type
◦ Cationic
24 II. Fundamental Principles of Organometallics Interactions
◦ σM→L or σL→M
◦ πM→L or πL→M
◦ δ
25 II. Fundamental Principles of Organometallics Coordination modes ◦ μ – metal centers coordinated to the same atom ◦ η – hapticity, ligand atoms coordinated to metal ◦ κ – polydentate ligands, denotes ligating atoms
26 II. Fundamental Principles of Organometallics 18 e- rule ◦ Metals go up to 6-coordinate ◦ Valence orbitals on the metal ◦ 9 orbitals (5d, 3p, 1s) ◦ Empirically derived ◦ Valid: ◦ Oh with large field splitting (Δo) ◦ Ligands are strong σ-donors or π-acceptors ◦ Not as valid: ◦ Weak field ligands (> 18e-) ◦ π-donor ligands (< 18e-) ◦ Square planar (16e- rule)
27 II. Fundamental Principles of Organometallics Crystal field theory
28 II. Fundamental Principles of Organometallics Ligand field theory
29 II. Fundamental Principles of Organometallics
Ligand field theory ◦ Ligand spectrochemical series ◦ Small Δ to large Δ ◦ Stems from a mix of σ- and π- interactions ◦ Metal spectrochemical series ◦ Δ increases with oxidation state Mn2+ < Ni2+ < Co2+ < Fe2+ < V2+ < Fe3+ < Cr3+ < V3+ < Co3+ ◦ Δ increases from 1st to 3rd row
30 II. Fundamental Principles of Organometallics
Dewar-Chatt-Duncanson ◦ Zeitse’s salt
31 II. Fundamental Principles of Organometallics
Dewar-Chatt-Duncanson
◦ HOMOPt(II)sp to LUMOC2H4
32 II. Fundamental Principles of Organometallics
Dewar-Chatt-Duncanson
◦ HOMOC2H4 to LUMOPt(II)sp
33 In Chemiae Veritas: Outline Existential Motivation History of organometallics Fundamental principles of: ◦ 18 e- rule ◦ Crystal field theory ◦ Ligand field theory ◦ Metal-carbon bonding Applications to catalysis ◦ Fundamental mechanisms ◦ Case studies
34 III. Applications to Catalysis: Mechanisms Ligand substitution ◦ Associative ◦ < 18e- ◦ Dissociative ◦ 18e- ◦ Interchange
http://chemwiki.ucdavis.edu/Inorganic_Chemistry/ 35 III. Applications to Catalysis: Mechanisms Oxidative addition ◦ Non-polar ◦ Concerted ◦ Polar ◦ Either concerted or step ◦ Can be radical ◦ More e- on metal promotes O/A ◦ e- poor R ◦ Less steric hindrance promotes O/A
Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. 36 III. Applications to Catalysis: Mechanisms Reductive Eliminations ◦ Non-polar bonds ◦ Tend to be easier ◦ Polar bonds ◦ More difficult for very electronegative groups (F, CN, etc.) ◦ Microscopic reverse of O/A ◦ Less e- on metal promotes R/E ◦ e- rich R and X ◦ More steric hindrance promotes R/E
Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. 37 III. Applications to Catalysis: Mechanisms Migratory Insertion ◦ No redox chemistry at the metal
http://chemwiki.ucdavis.edu/Inorganic_Chemistry/ Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. 38 III. Applications to Catalysis: Mechanisms Migratory Insertion ◦ No redox chemistry at the metal ◦ Stereochemical control
http://chemwiki.ucdavis.edu/Inorganic_Chemistry/ Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. 39 III. Applications to Catalysis: Mechanisms Elimination Reaction ◦ Often in equilibrium with E1 insertion
◦ Driving force is M-X E2 bond or Le Châtelier
http://chemwiki.ucdavis.edu/Inorganic_Chemistry/ 40 Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. III. Applications to Catalysis: Mechanisms Alkene/Alkyne Metathesis ◦ Nobel Prize 2005 ◦ Cross-metathesis ◦ Ring opening ◦ Ring closing ◦ Equilibrium reaction ◦ Driving force is thermodynamics
http://chemwiki.ucdavis.edu/Inorganic_Chemistry/ Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. 41 III. Applications to Catalysis: Mechanisms Alkene/Alkyne Metathesis ◦ Nobel Prize 2005 ◦ Cross-metathesis ◦ Ring opening ◦ Ring closing ◦ Equilibrium reaction ◦ Driving force is thermodynamics
http://chemwiki.ucdavis.edu/Inorganic_Chemistry/ Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. 42 III. Applications to Catalysis: Catalysis Principles of catalysis ◦ A substance which increases the rate of a reaction without being consumed (Otswald, 1894) ◦ Stabilize the transition state O/M has “extra mechanisms” ◦ Stereochemical control ◦ Isomerization equilibria Thermodynamically downhill ◦ At a given T and P Transition metal mediated ◦ Open coordination (16 or 14e-)
Crabtree, R. H. Chem. Rev. 2015, 115, 127-150. Astruc, D. Organometallic Chemistry and Catalysis; Springer: Berlin, Germany, 2007. 43 Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. III. Applications to Catalysis: Case Study Hydrogenation of alkenes ◦ Wilkinson- Osborn catalyst (1964)
Astruc, D. Organometallic Chemistry and Catalysis; Springer: Berlin, Germany, 2007. 44 III. Applications to Catalysis: Case Study Olefin isomerization (migration)
Astruc, D. Organometallic Chemistry and Catalysis; Springer: Berlin, Germany, 2007. 45 III. Applications to Catalysis: Case Study Monsanto acetic acid process
Astruc, D. Organometallic Chemistry and Catalysis; Springer: Berlin, Germany, 2007. 46 III. Applications to Catalysis: Case Study Wacker Process (1953)
Astruc, D. Organometallic Chemistry and Catalysis; Springer: Berlin, Germany, 2007. 47 III. Applications to Catalysis: Outlook Examples of heterogenous catalysis
Crabtree, R. H. Chem. Rev. 2015, 115, 127-150. Astruc, D. Organometallic Chemistry and Catalysis; Springer: Berlin, Germany, 2007. 48 Hartwig, J. Organotransition Metal Chemistry; University Science Books: Sausalito, CA, 2010. Summary Organometallics marries organic principles and inorganic principles to a “hybrid” field Inorganic mechanisms are unique and therefore can catalytically control an organic reaction very precisely Most reactivity can be rationalized by first principles Designing better catalysts can be done from first principles You need open coordination sites to do catalysis Good catalysts change the world
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