Reactions of heterodinuclear Fe-Pt and Fe-Pd complexes with cyclic bis(amino)germylenes and -stannylenes: A bridging metal(II) amide unit between two different transition metal centers and donor stabilization of terminal germylene and stannylene ligands by Si(OMe)(3)

Reaction of the cyclic amides EN(t)BuSiMe(2)N(t)Bu (E = Ge, Sn) with the heterobimetallic complexes [(OC)(3)Fe(mu-CO)(mu-Ph(2)PXPPh(2))Pt(PR(3))](Fe-Pt) (X = CH2, NH; R = phenyl, p-tolyl) occurs by selective substitution of the bridging carbonyl ligand and yields the stannylene- and germylene-bridged complexes [(OC)(3)Fe{mu-EN(t)BuSiMe(2)N(t)Bu}(mu-Ph(2)PXPPh(2))Pt(PR(3))](Fe-Pt) (2a, X = CH2, E = Sn, R = Ph; 2b, X = NH, E = Sn, R = Ph; 2c, X = CH2, E = Sn, R p-tol; 3a, X = CH2, E = Ge, R = Ph; 3b, X = NH, E = Ge, R = Ph). When GeN(t)BuSiMe(2)N(t)Bu was added in excess to the germylene complex 3a, the tetranuclear complex [(OC)(3)Fe{mu-GeN(t)BuSiMe(2)N(t)Bu} (mu-dppm)Pt {GeN(t)BuSiMe(2)N(t)Bu}](Fe-Pt) (4) was formed, which is in equilibrium with 3a. The heterobimetallic Si(OMe)(3)-substituted complexes mer-[(OC)(3)Fe{mu-Si(OMe)(2)(OMe)} (mu-dppm)M(Me)](Fe-M) (M = Pd, Pt) react with EN(t)BuSiMe(2)N(t)Bu (E = Ge, Sn) by opening of the four-membered Fe-Si-O-M ring to give the complexes mer-[(OC)(3)Fe{mu-Si(OMe)(2)(OMe)}{EN(t)BuSiMe(2)N(t)Bu}{mu-dppm)M} (Me)](Fe-M) (5, M = Pt, E = Sn; 6, M = Pd, E = Sn; 7, M = Pd, E = Ge) which contain a five-membered Fe-Si-O-E-M ring. The expected insertion of the amides EN(t)BuSiMe(2)N(t)Bu into the M-Me bond was not observed. The dynamic behavior of these intramolecularly base-stabilized trimetallic germylene and stannylene complexes, which is due to a rapid exchange of the methoxy groups coordinated an E, was investigated by variable-temperature IH-NMR spectroscopy. All complexes were characterized by multinuclear NMR spectroscopy, and the solid-state structure of 7 was determined by X-ray diffraction.