Cadmium complexes bearing Me2N^E^O− (E = S, Se) organochalcogenoalkoxides and their zinc and mercury analogues

International audienceHeteroleptic zinc and cadmium complexes of the type [{N^E^O}M-Nu] (M = Zn, Cd; E = S, Se; R = CH, CF; Nu = N(SiMe), I, Cl; n = 1-2) were prepared by reacting the alcohol proteo-ligands {N^E^O}H with [M(N(SiMe))] (M = Zn, Cd) or [XMN(SiMe)] (M = Zn, X = Cl; M = Cd, X = I) in an equimolar ratio. These group 12 metal complexes were characterised in solution by multinuclear NMR spectroscopy and their solid-state structures were determined by X-ray diffractometry. The ligands {N^E^O} bearing CH groups in α position to the alkoxide behave as κ-O,E-bidentate moieties (E = S, Se) and form centro-symmetric dinuclear O-bridged heteroleptic alkoxo-amido complexes both with zinc and cadmium, with four-coordinate metal centres resting in tetrahedral environments. By contrast, complexes supported by the CF-substituted {N^E^O} crystallise as tetrahedral mononuclear species, with tridentate κ-N,O,E-coordinated ligands. These structural differences resulting from changes in the ligand skeleton and in the electron-donating properties of the alkoxide were also observed in solution. Attempts to prepare congeneric heteroleptic mercury complexes from [Hg(N(SiMe))] unexpectedly only afforded homoleptic bis(alkoxide)s such as [{N^S^O}Hg]. Owing to the strong Hg-C bond, treatment of [PhHgN(SiMe)] with {N^S^O}H afforded the heteroleptic, T-shaped [{N^S^O}HgPh] mercuric alkoxide upon elimination of hexamethyldisilazane. [{N^S^O}Hg] and [{N^S^O}HgPh] constitute very rare examples of structurally characterised mercuric alkoxides