Synthesis and structural characterization of scandium SALEN complexes

摘要

A series of heteroleptic scandium SALEN complexes, [(SALEN)Sc(mu-Cl)](2) and (SALEN)Sc[N(SiHMe2)(2)] is obtained via amine elimination reactions using [Sc(N'Pr-2)(2)(mu-Cl)(THF)](2) and Sc[N(SiHMe2)(2)](3)(THF) as metal precursors, respectively. H(2)SALEN ligand precursors comprising H(2)Salen [(1,2-ethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H(2)Salpren [(2,2-dimethylpropanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenoll] H(2)Salcyc [((1R,2R)-(-)-1,2-cyclohexanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] and H(2)Salphen [((1S,2S)-(-)-1,2diphenylethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] are selected according to solubility and ligand backbone variation (''=N-(R)-N='' bite angle) criteria. Consideration is given to the feasibility of [Cl -> NR2] and [N(SiHMe2)(2) -> OSiR3] secondary ligand exchange reactions. X-ray crystal structure analyses of donor-free (Salpren)Sc(N'Pr-2), (R,R)-(Salcyc)Sc[N(SiHMe2)(2)], (Salen)Sc(OSi'BuPh2) and (Salphen)Sc(OSiH'Bu-2) reveal (i) a very short Sc-N bond distance of 2.000(3) (A) over circle, (ii) weak beta(Si-H)amido agostic interactions and (iii) an exclusive intramolecularly tetradentate and intrinsically bent coordination mode of the SALEN ligands with <(Ph,Ph) dihedral angle's and Sc-[N2O2] distances in the 124.27(9)-127.7(3)degrees and 0.638(1)-0.688(1) (A) over circle range, respectively.