Synthesis and characterisation of penta- and hexa-platinum cluster compounds

Abstract

The reactions of the pentaplatinum cluster compounds [Pt₅(µ-SO₂)_x(µ-CNC₈H₉)_3–x(CNC₈H₉)₇](x= 0, 2 or 3) with SO₂ and CNC₈H₉(CNC₈H₉= 2,6-dimethylphenyl isocyanide) have been studied. The cluster compound [Pt₅(µ-CNC₈H₉)₃(CNC₈H₉)₇]1 was initially synthesised from the reduction of [Pt(CNC₈H₉)₂Cl₂] with cobaltocene. It reacts with SO₂ to give [Pt₅(µ-SO₂)₃(CNC₈H₉)₇]2. The reaction of CNC₈H₉ with 2 results in the formation of [Pt₆(µ-SO₂)₂(µ-CNC₈H₉)(CNC₈H₉)₇]3. The structures of 2 and 3 have been solved using single-crystal X-ray crystallography and both are based on an edge-bridged tetrahedral metal core. They are unusual, both containing only three bridging and seven terminal ligands. In the reaction of 1 with SO₂ a small amount of [Pt₆(µ-SO₂)₃(CNC₈H₉)₉] was isolated. This compound was characterised on the basis of IR, ¹H NMR spectroscopy and fast atom bombardment mass spectrometry The metal framework geometry is thought to be related to an edge-bridged trigonal bipyramid.