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(μ-CO)(μ-Ph 2 PXPPh 2 )Pt(PR 3 )]( Fe − Pt ) (X = CH 2, 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{μ-EN t BuSiMe 2 N t Bu}(μ-Ph 2 PXPPh 2 )Pt(PR 3 )]( Fe − Pt ) ( 2a, X = CH 2, E = Sn, R = Ph; 2b, X = NH, E = Sn, R = Ph; 2c, X = CH 2, E = Sn, R = p -tol; 3a, X = CH 2, 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{μ-GeN t BuSiMe 2 N t Bu}(μ-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{μ-Si(OMe) 2 (OMe)}(μ-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 me r-[(OC) 3 Fe{μ-Si(OMe) 2 (OMe)}{EN t BuSiMe 2 N t Bu}{μ-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 on E, was investigated by variable-temperature 1 H-NMR spectroscopy. All complexes were characterized by multinuclear NMR spectroscopy, and the solid-state structure of 7 was determined by X-ray diffraction.