Isonitrile μ2-carbido complexes

Abstract

The μ-carbido complex [WPt(μ-C)Br(CO)₂(PPh₃)₂(Tp*)] (Tp = hydrotris(dimethylpyrazolyl)borate) undergoes substitution of one phosphine ligand with isonitriles to afford complexes [WPt(μ-C)Br(CNR)(CO)₂(PPh₃)(Tp*)] (R = ^tBu, C₆H₃Me₂-2,6, C₆H₂Me₃-2,4,6). For aryl but not alkyl isocyanides disubstitution follows to afford [WPt(μ-C)Br(CNR)₂(CO)₂(Tp*)] (R = C₆H₂Me₂-2,6, C₆H₂Me₃-2,4,6). The bis(isonitrile) derivatives, including [WPt(μ-C)Br(CN^tBu)₂(CO)₂(Tp*)], may also be prepared from the reactions of triangulo-[Pt₃(CNR)₆] with [W(CBr)(CO)₂(Tp*)]. Bis- and tris(dimethylpyrazolyl)borate pro-ligand salts replace the bromide and one phosphine in [WPt(μ-C)Br(CNC₆H₂Me₃)(CO)₂(PPh₃)(Tp*)] or the bromide and one isonitrile in [WPt(μ-C)Br(CNC₆H₂Me₃)₂(CO)₂(Tp*)] to afford [WPt(μ-C)(CNC₆H₂Me₃)(CO)₂(Tp*)(L)] (L = κ²-Tp*, dihydrobis(pyrazolyl)borate). Structural, spectroscopic and computational data for the complexes are discussed to interrogate the nature of the WC–Pt carbido bridge by analogy with a range of other sp-C₁ and sp-B₁ ligands (CN, CCH, CP, CAs, CSb, CNO, BO, BNH and BCH₂).