Transition-metal Schiff-base complexes as ligands in tin chemistry. Part 7. Reactions of organotin(IV) Lewis acids with [M(L)] 2 [M=Ni, Cu and Zn; H 2L= N,N′-bis(3-methoxysalicylidene)benzene-1,3-diamine and its -1,4-diamine analog

Abstract

Dinuclear complexes [M(3MeO-sal- m-phen)(H 2O)] 2 [M=Cu, Ni and Zn; 3MeO–H 2sal- m-phen= N,N′-bis(3-methoxysalicylidene)benzene-1,3-diamine] and [M(3MeO-sal- p-phen)(H 2O)] 2 [M=Cu, Ni and Zn; 3MeO–H 2sal- p-phen= N,N′-bis(3-methoxysalicylidene)benzene-1,4-diamine] were synthesised and reacted with diorganotin(IV) dihalides, dinitrates and dithiocyanates. Only in the case of those reactions involving [M(3MeO-sal- m-phen)(H 2O)] 2 with M=Ni or Zn were adducts obtained as the sole products of reaction; the adducts were all tetranuclear complexes. The tetranuclear adduct {(SnBu n 2).[Ni(3MeO-sal- m-phen)(NCS) 2]} 2· 6MeCN results from salicylaldimine ligands, related by a 2-fold axis, adopting bridging roles by co-ordinating to each of the symmetry related nickel atoms through phenolic oxygen and imine nitrogen atoms, while their phenolic and methoxy oxygen atoms form donor bonds to the tin atoms of symmetry related dibutyltin cations. The salicylaldimine ligands, related by inversion, adopt the same bridging role towards the nickel atoms in the adduct {[SnBz 2(NO 3)]·[Ni(3MeO-sal- m-phen)(NO 3)]} 2.6MeCN (Bz=benzyl), but as a result of the bidentate role of the nitrate co-ordinated to nickel, the arrangement of the phenolic and methoxy oxygens is such that each tin is co-ordinated quite strongly by a bidentate nitrate, a methoxy and two phenolic oxygen atoms while a second methoxy oxygen provides a weak Sn–O interaction, thus resulting in pseudo eight co-ordinate tin. 119Sn Mössbauer parameters indicate that all of the adducts of di- and triorganotin halides are organotin aqua adducts with the donor water engaged in hydrogen bonding with Schiff-base oxygen atoms.