Synthesis of complexes of ReV, RuII, OsII, RhI, IrI and IrIII. Crystal and molecular structures of [ReO(OH)(SC6H4 SiPh3-2)2(PPh3)], [ReH4(SC6H4SiPh3-2)(PPh3)3] and [IrH(SC6H4SiPh3-2)2(PMePh2)3]
Abstract
The rhenium(V) precursors [ReOX3(PPh3)2](X = Cl or Br) reacted with 2-triphenylsilylbenzenethiol in methanol in the presence of base to give [ReO(Cl)(SC6H4SiPh3-2)2(PPh3)]1 and [ReO(OH)(SC6H4SiPh3-2)2(PPh3)]2 respectively. In the presence of NaBH4 and no base the blue thiolate polyhydride [ReH4(SC6H4SiPh3-2)(PPh3)3]3 was formed in high yield. The crystal structures of 2 and 3 were determined and showed 2 to be monomeric with distorted trigonal-bipyramidal geometry and the oxide and hydroxide ligands in equatorial sites. The thiolate and phosphine ligands of 3 are in a tetrahedral array with the hydride ligands assumed to be in capping sites on the tetrahedral faces. Reaction of the thiol with [IrCl3(PMePh2)3] in methanol in the presence of NEt3 gave [IrH(SC6H4SiPh3-2)2(PMePh2)3]4 in good yield. Its crystal structure revealed the geometry about the Ir to be pseudo-octahedral with mer phosphine ligands and cis thiolates, and the hydride presumed to be in a vacant site trans to a thiolate ligand. The complex [IrCl(CO)(PPh3)2] reacted under similar conditions to give monomeric [Ir(SC6H4SiPh3-2)(CO)(PPh3)2]6 whereas [RhCl(CO)(PPh3)2] gave [Rh2(µ-SC6H4SiPh3-2)2(CO)2(PPh3)2]5; [OsH(Cl)(PPh3)3] gave [OsH(SC6H4SiPh3-2)(CO)(PPh3)3]7 whereas [RuH(Cl)(PPh3)2] formed [Ru(SC6H4SiPh3-2)(CO)(PPh3)2]8. The potentially bidentate thiol SiPh2(C6H4SH-2)2 gave a series of products with the same precursors which proved difficult to characterise unequivocally in the absence of X-ray structural data. The geometry adopted by the SC6H4SiPh3-2 ligand was analysed in some detail and contrasted with symmetrically 2,6-disubstituted aromatic thiolates.
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