. Can. J. Chem. 53,307 (197.5). "%n Mossbauer spectra have been recorded for eleven tin-nickel compounds of the type CI,Sn [NiLCp],-, (L = CO, PPh3; x = 2, 3) and C13SnNiL2Cp.S (S = solvent molecule). The center shifts are used to distinguish coordinated SnCI, and uncoordinated ionic SnC13-, respectively. In the SnC13-compounds, the Mossbauer parameters indicate that the solvent molecules are not bonded to the Sn atom. In compounds containing Sn-Ni bonds, the center shifts and quadropole splittings show that Ni(PPh3)Cp is the best donor of the first row transition metal moieties, and that the Sn-Ni bond has the highest Sn s character. Ni(C0)Cp is a slightly poorer donor than Ni(PPh,)Cp, and the Sn-Ni bond has a smaller s character. [Traduit par le journal]