Role Of Metal Center And Coordination Environment In M-(Z)-N-((E)-Pyridin-2-Ylmethylene)Isonicotinohydrazonate (M = La-Iii, Zn-Ii, Cd-Ii Or Hgii) Catalyzed Cyanosilylation Of Aldehydes

A series of known metal complexes, [LaL2(NO3)(H2O)(2)]center dot 5H(2)O (1), [Zn(mu-L)(NO3)(H2O)](n) (2), {[Cd-2(mu-HL)(mu-L) (NO3)(3)(H2O)]center dot H2O}(n) (3) and [Hg(mu-L)(N-3)]n center dot nH(2)O (4), were synthesized from the corresponding metal salts and 2-pyridinecarboxaldehyde isonicotinoylhydrazone (HL), and demonstrated high activity and selectivity in the cyanosilylation of aldehydes. Although all the complexes are derived from the same HL hydrazone ligand, the catalytic activity of 1-4 is different and relates to the metal center and coordination environment, whereas complex 1 being the most effective homogeneous Lewis acid-base catalyst towards the synthesis of cyanohydrin trimethylsilyl ethers from both aliphatic and aromatic aldehydes with yields up to 96.3 % in 6 h in methanol solution and at room temperature. According to the proposed mechanism, both coordination and noncovalent interactions (hydrogen and tetrel bonds) play a significant role and account for the higher catalytic activity of complex 1.