Phosphonate-stannylene coupling in the reactions of the anion [Mn2{μ-OP(OEt)2}{μ-P(OEt)2}(CO)6]2- with SnR2Cl2 (R = Bu, Ph)

Reaction of Na-2[Mn-2{U-OP(OEt)(2)}{mu-P(OEt)(2)}(CO)(6)] with SnR2Cl2 (R = Bu, Ph) in tetrahydrofuran leads finally to the stannyl-bridged heptacarbonyl compounds [Mn-2{mu-Sn: Sn,P-SnR2OP(OEt)(2)}{mu-P(OEt)(2)}(CO)(7)] or, in the presence of PR'(3) (R' = Ph, p-tol, Cy, Pr-i), to the corresponding hexacarbonyl complexes [Mn-2{mu-Sn:Sn,P-SnR2OP(OEt)(2)}{mu-P(OEt)(2)}(CO)(6)(PR'(3))]. Several intermediates are involved in these reactions, which include the expected initial stannylene product [Mn-2(mu-SnR2){mu-OP(OEt)(2)}{mu-P(OEt)(2)}(CO)(6)], detected when R = Bu, and unstable solvent adducts. The products isolated all display a one-electron-donor stannyl bridging group derived from the O-Sn coupling between the phosphonate and stannylene ligands present in the initial intermediate, as confirmed by an X-ray study on [Mn-2{mu-Sn:Sn,P-SnPh2OP(OEt)(2)}(CO)(6)((PPr3)-Pr-i)] and the spectroscopic (IR, H-1 and P-31 NMR) analysis of the new complexes.