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Group 4 Organometallics Supported by Sterically Hindered β ‐Diketonates
Author(s) -
Hopkins Emily J.,
Krajewski Sebastian M.,
Crossman Aaron S.,
Maharaj Franklin D. R.,
Schwanz Logan T.,
Marshak Michael P.
Publication year - 2020
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.202000135
Subject(s) - chemistry , steric effects , reactivity (psychology) , metathesis , ligand (biochemistry) , medicinal chemistry , thermal decomposition , alkyl , migratory insertion , salt metathesis reaction , catalysis , metal , metal carbonyl , stereochemistry , organic chemistry , polymerization , medicine , biochemistry , alternative medicine , receptor , pathology , polymer
The synthesis, characterization, and reactivity of group 4 organometallics supported by β ‐diketonates is reported. Sterically hindered β ‐diketonates, such as 2,6‐dimesitylbenzoyl pinacolone ( L 1 ) and 2,6‐dimesitylbenzoyl acetylmesitylene ( L 2 ), preclude the formation of tetrakis‐ and tris‐chelates, halting at cis ‐octahedrally coordinated M( L n ) 2 Cl 2 (M = Ti, Zr, Hf; L n = L 1 , L 2 ). Metathesis with benzylmagnesium chloride affords M( L n ) 2 Bn 2 (M = Zr, Hf) and the reduced Ti( L 1 ) 2 Bn(THF) species. These are the first structurally‐characterized metal alkyl complexes exclusively supported by β ‐diketonates among the group 4 metals. Thermolysis of Zr( L n ) 2 Bn 2 complexes results in unimolecular migratory insertion reaction, forming an enone by‐product and ZrO 2 . Combined Eyring analyses and computational investigations suggest the bond rearrangements are initiated by an initial benzyl migration reaction to the less hindered carbonyl group on the ligand. Activation of M( L n ) 2 Bn 2 (M = Zr, Hf) in the presence of olefins resulted in similar oxygen abstraction. Implications and prospects for β ‐diketonate‐supported catalysis are discussed.