REACTIONS OF HETERODINUCLEAR FE-PT AND FE-PD COMPLEXES WITH CYCLIC BIS(AMINO)GERMYLENES AND BIS(AMINO)STANNYLENES - A BRIDGING METAL(II) AMIDE UNIT BETWEEN 2 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 t he 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 subs titution of the bridging carbonyl ligand and yields the stannylene- an d germylene-bridged complexes uSiMe(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; 2 c, 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)Bu SiMe(2)N(t)Bu} (mu-dppm)Pt {GeN(t)BuSiMe(2)N(t)Bu}](Fe-Pt) (4) was for med, 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 -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-me mbered Fe-Si-O-E-M ring. The expected insertion of the amides EN(t)BuS iMe(2)N(t)Bu into the M-Me bond was not observed. The dynamic behavior of these intramolecularly base-stabilized trimetallic germylene and s tannylene complexes, which is due to a rapid exchange of the methoxy g roups coordinated an E, was investigated by variable-temperature IH-NM R spectroscopy. All complexes were characterized by multinuclear NMR s pectroscopy, and the solid-state structure of 7 was determined by X-ra y diffraction.