SYNTHETIC, SPECTROSCOPIC AND STRUCTURAL STUDIES ON PHOSPHINE-STABILIZED [PPH(3),PH(2)PCH(2)PPH(2),PH(2)P(CH2)(4)PPH(2), (PH(2)P)C5H4N] MAIN-GROUP ELEMENT-IRON-SILICON CHAIN COMPLEXES

The reaction between K[Fe(CO)(3)(PPh(3))(Si(OMe)(3))] and InX(3) (X = Cl or Br) gave complexes of the type Fe-In(mu-X)(2)In-Fe. The chloride-bridged complexes easily form adducts with two-electron donors such as pyridine or O=PPh(3). The structure of the chlorobenzene solvate of mer-[(Ph(3)P)(OC)(3)Fe{mu-Si(OMe)(2) (OMe))InCl2(O=PPh(3))] was determined by X-ray diffraction. An oxygen-indium interaction was established which results in a four-membered Fe-Si-O-In ring. This interaction was also evidenced by a variable-temperature H-1 NMR study. The reaction of 2 equivalents of K[Fe(CO)(3)(PPh(3))(Si(O Me)(3)}] with InCl3 gave the trinuclear complex mer-InCl(Fe(CO)3(PPh3)[mu-Si(OMe)(2)(OMe)]}(2)] which reacts with O=PPh(3) to yield mer-[InCl(O=PPh(3)){Fe(CO)(3)(PPh(3))[Si(OMe)(3)]}(2)]. With GaCl3 and K[(CO)(3){Si(OMe)(3)}(dppm-P)] (dppm = Ph(2)PCH(2)PPh(2)) the complex mer-[{(MeO)(3)Si}(OC)(3)Fe(mu- dppm)GaCl2] was formed, in which the Fe-Ga bond is stabilised by a bridging dppm ligand. The corresponding complex mer-[{(MeO)(3)Si}(OC)(3)Fe(mu-dppm)InCl2] was used in the synthesis of trimetallic complexes of the type mer-[{(MeO)(3)Si)(OC)(3)Fe(mu-dppm)InCl(M')] [M' = Mo(C5H4 Me)(CO)(3) or W(C5H5)(CO)(3)]. The structure of the chlorobenzene solvate of the molybdenum complex was determined by X-ray diffraction. Reaction of K[Fe(CO)(3){Si(OMe)(3)}(dppm-P)] and [SnCl(2)Ph(2)] yielded the trimetallic complexes mer-[SnPh(2)(Fe(CO)(3)[Si(OMe)(3)](dppm-P)}(2)] and mer,cis-[Fe(CO)(3)(dppm)(SnClPh(2))(2)]. The structure of the CH2Cl2 solvate of the latter was determined by X-ray diffraction. Bridging by the dppm ligand was deduced from the (1)J(P-Sn) couplings detected by P-31-(H-1) NMR spectroscopy. This result contrasts with the long P-Sn distance of 3.140 Angstrom found in the crystal structure. This complex represents the first Fe-Sn complex containing a bridging dppm ligand. With K[Fe(CO)(3){Si(OMe)(3)}{(Ph(2)P)C5H4N)] the new bimetallic complexes mer-[{[(MeO)(3)Si] (OC)(3)Fe[mu-(Ph(2)P)C5H4N]Zn(mu-Cl)}(2)] and mer-[{(MeO)(3)Si)(OC)(3)Fe{mu-(Ph(2)P)C5H4N)MCl(2)] (M = Ga or In) have been prepared. The reactivity of the first towards donor ligands such as isocyanides or 4-methylpyridine was studied. It also reacts in non-polar solvents with an equivalent of K[Fe(CO)(3)(PPh(3)){Si(OMe)(3)}] to give the trimetallic chain complex [Zn(Fe(CO3- [Si(OMe)(3)][mu-(Ph(2)P)C5H4N]}(2)] which transforms into an ionic species mer-[{(MeO)(3)Si)(OC)(3)Fe{(Ph(2)P)C5H4N}Zn] [Fe(CO)(3){Si(OMe)(3)}{(Ph(2)P)C5H4N}] in donor solvents like tetrahydrofuran. Complexes containing the cyanometalate (C(5)H(4)Me) Mn(CO)(2)(CN) are also described.