SCHEDULED MAINTENANCE
Synthetic, spectroscopic and structural studies on phosphine-stabilised [PPh3, Ph2PCH2PPh2, Ph2P(CH2)4PPh2, (Ph2P)C5H4N] main group element–iron–silicon chain complexes
Abstract
The reaction between K[Fe(CO)3(PPh3){Si(OMe)3}] and InX3(X = Cl or Br) gave complexes of the type Fe–In(µ-X)2In–Fe. The chloride-bridged complexes easily form adducts with two-electron donors such as pyridine or O![[double bond, length half m-dash]](https://www.rsc.org/images/entities/char_e006.gif)
PPh3. The structure of the chlorobenzene solvate of mer-[(Ph3P)(OC)3Fe{µ-Si(OMe)2([graphic omitted]nCl2(OPPh3)] 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 1H NMR study. The reaction of 2 equivalents of K[Fe(CO)3(PPh3){Si(OMe)3}] with InCl3 gave the trinuclear complex mer-[graphic omitted]Me)]}2] which reacts with OPPh3 to yield mer-[InCl(OPPh3){Fe(CO)3(PPh3)[Si(OMe)3]}2]. With GaCl3 and K[(CO)3{Si(OMe)3}(dppm-P)](dppm = Ph2PCH2PPh2) the complex mer-[{(MeO)3Si}(OC)3Fe(µ-dppm)GaCl2] was formed, in which the Fe–Ga bond is stabilised by a bridging dppm ligand. The corresponding complex mer-[{(MeO)3Si}(OC)3Fe(µ-dppm)InCl2] was used in the synthesis of trimetallic complexes of the type mer-[{(MeO)3Si}(OC)3Fe(µ-dppm)InCl(M′)][M′= Mo(C5H4Me)(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 [SnCl2Ph2] yielded the trimetallic complexes mer-[SnPh2{Fe(CO)3[Si(OMe)3](dppm-P)}2] and mer,cis-[Fe(CO)3(dppm)(SnClPh2)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 1J(P–Sn) couplings detected by 31P-{1H} NMR spectroscopy. This result Contrasts with the long P–Sn distance of 3.140 Å 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}{(Ph2P)C5H4N}] the new bimetallic complexes mer-[{[(MeO)3Si](OC)3Fe[µ-(Ph2P)C5H4N]Zn(µ-Cl)}2] and mer-[{(MeO)3Si}(OC)3Fe{µ-(Ph2P)C5H4N}MCl2](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(PPh3){Si(OMe)3}] to give the trimetallic chain complex [Zn{Fe(CO)3[Si(OMe)3][µ-(Ph2P)C5H4N]}2] which transforms into an ionic species mer-[{(MeO)3Si}(OC)3Fe{µ-(Ph2P)C5H4N}Zn][Fe(CO)3{Si(OMe)3}{(Ph2P)C5H4N}] in donor solvents like tetrahydrofuran. Complexes containing the cyanometalate (C5H4Me) Mn(CO)2(CN) are also described.
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