SYNTHESIS AND REACTIVITY OF PHOSPHINE-SUBSTITUTED HYDRIDO SILYL COMPLEXES MER-[FEH(SIR3)(CO)3[PH2P(CH2)NPPH2]] (N = 1 OR 4), MER-[FEH[SI(OME)3](CO)3(PPH2H)] AND MER-[FEH[SI(OME)3](CO)3[PH2PCH2C(O)PH]] - SYNTHESIS OF BIMETALLIC COMPLEXES AND CRYSTAL-STRUCTURE OF MER-[(PH3P)CU(MU-DPPM)FE[SI(OME)3](CO)3]

Phosphine-substituted hydrido silyl complexes [FeH(SiR3)(CO)3L] (L = phosphine) have been prepared by carbonyl substitution in cis-[FeH(SiR3)(CO)4]. The reaction of cis-[FeH{Si(OMe)3}(CO)4] 1a with Ph2PCH2PPh2(dppm) in a 1:1 ratio afforded mer-[FeH{Si(OMe)3}(CO)3(dppm-P)] 2a; mer-[FeH{Si(OEt)3}(CO)3(dppm-P)] 2b was obtained similarly. The reaction of [FeH(SiPh3)(CO)4] with Ph2P(CH2)4PPh2(dppb) afforded mer-[FeH(SiPh3)(CO)3(dppb-P)] 3a and that of 1a with vinylidenebis(diphenylphosphine) (vdpp) afforded under analogous conditions the chelated complex cis-[FeH{Si(OMe)3}(CO)2(vdpp-PP')] 3c. Reaction of 1a with the functional phosphine Ph2PCH2C(O)Ph yielded mer-[FeH{Si(OMe)3}(CO)3{Ph2PCH2C(O)Ph}] 4 and with PPh2H, mer-[FeH{Si(OMe)3}(CO)3(PPh2H)] 5 was obtained. The anionic complexes K[Fe(SiR3)(CO)3(PPh2X)] 6a (R = OMe, X = CH2PPh2), 6b (R = OEt, X = CH2PPh2), 6c [R = Ph, X = (CH2)4PPh2] and 6d [R = OMe, X = CH2C(O)Ph] were generated from the corresponding hydrido complexes by deprotonation with excess of KH in tetrahydrofuran (thf). They were used to prepare metal-metal bonded heterobinuclear complexes mer-[LM(mu-dppm)Fe{Si(OMe)3}(CO)3] 7b (M = Cu, L = PPh3), 7c (M = Cu, L = MeCN), 8a (M = Ag, L = AsPh3), 8b (M = Ag, L = PPh3) and 10 (M = Au, L = PPh3). Complex 8a dissociates AsPh3 in solution with formation of mer-[activated Ag(mu-dppm)Fe{(MeO)Si(OMe)2}(CO)3] 9, which contains an unusual alkoxysilyl bridge resulting in a AgFeSiO four-membered ring. This very labile complex was also obtained from the reaction of 6a with [Ag(MeCN)2]NO3. For comparative purposes, we also prepared mer-[(Ph3P)AuFe{Si(OMe)3}(CO)3(PPh3)] 11. All complexes were characterized by elemental analysis and spectroscopic (IR and H-1 and P-31-{H-1} NMR) methods. The crystal structure of compound 7b has been determined by X-ray diffraction: monoclinic, space group P2(1)/c, with a = 11.542(5), b = 18.567(7), c = 21.830(7) angstrom, beta = 94.67(2)-degrees and Z = 4. The copper atom is trigonally co-ordinated by two phosphorus atoms from the dppm and PPh3 ligands and by the Fe atom [Fe-Cu = 2.540(2) angstrom]. The Fe atom is in an octahedral arrangement determined by three carbon atoms from carbonyl groups, a phosphorus atom of the bridging dppm ligand and by the Si atom of the Si(OMe)3 group.