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Synthesis, Structure and Solution Studies on Mixed Aryl/Alkyl Lithium Zincates
Author(s) -
Roberts Andrew J.,
Kennedy Alan R.,
McLellan Ross,
Robertson Stuart D.,
Hevia Eva
Publication year - 2016
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.201601020
Subject(s) - chemistry , homoleptic , aryl , reagent , tetramethylethylenediamine , lithium (medication) , alkyl , monomer , yield (engineering) , toluene , benzene , medicinal chemistry , crystallography , organic chemistry , metal , polymer , medicine , endocrinology , materials science , metallurgy
Novel homo‐ and heteroleptic lithium zincates have been prepared by cocomplexation reactions of Zn(CH 2 SiMe 3 ) 2 and PhLi in low‐polarity hydrocarbon solvents. X‐ray crystallographic studies of products obtained by reacting the organometallic reagents in benzene or toluene yield the novel solvent‐free solid‐state arrangement [Li 4 Zn 3 Ph 5 (CH 2 SiMe 3 ) 5 ] ⋡ ( 1 ). Combining Zn(CH 2 SiMe 3 ) 2 and PhLi in hexane in the presence of the polydentate N‐donors PMDETA ( N , N , N′ , N′′,N′′ ‐pentamethyldiethylenetriamine) or TMEDA ( N , N , N′ , N′ ‐tetramethylethylenediamine) reveals monomeric heteroleptic [(PMDETA)LiZn(CH 2 SiMe 3 ) 2 Ph] ( 2 ) and homoleptic [(TMEDA)LiZn(CH 2 SiMe 3 ) 3 ] ( 3 ), the result of a disproportionation process, respectively. NMR spectroscopic studies suggest that 2 and 3 retain their discrete contacted ion‐pair solid‐state structures in benzene solution. Variable‐temperature NMR spectroscopic studies of 2 in [D 8 ]THF reveal a complex equilibrium also including [LiZn(CH 2 SiMe 3 ) 3 ], [LiZn(CH 2 SiMe 3 )Ph 2 ] and [LiZnPh 3 ], an equilibrium process analogous to that of 1 in THF. This study further highlights the complexity of these reactions, which at first would appear simple.