Synthesis and structural characterisation of the palladium cluster compounds [Pd3(μ-SO2)2(μ-PPh2py)2(PBz3)2] and [Pd4(μ-SO2)2(μ3-S)(CNR)(PBz3)4] (R = tBu, 2,6-dimethylphenyl and cyclohexyl)

Abstract

We have reported previously that the reaction of [Pd₂(dba)₃] (dba = dibenzylideneacetone) with PBz₃ in the presence of SO₂ yields [Pd₂(μ-SO₂)(μ-dba)(PBz₃)₂] (1) and [Pd₃(μ-SO₂)₃(PBz₃)₃] (2) (which can be prepared selectively by varying the concentration of SO₂). Here the reactions of 1 and 2 with PPh₂py (diphenylpyridine phosphine) to yield [Pd₂(μ-SO₂)(μ-PPh₂py)(PBz₃)₂] (4) and [Pd₃(μ-PPh₂py)₂(μ-SO₂)₂(PBz₃)₂] (5), respectively, are reported. Structural characterisation of 5 shows it to be an unusual trimetallic compound. The reaction between the tetrahedral cluster [Pd₄(μ₃-S)(μ-SO₂)₂(CO)(PBz₃)₄] (3) (which is prepared by reacting dimer 1 with COS) and CNR has also been studied. The isostructural clusters [Pd₄(μ₃-S)(μ-SO₂)₂(CNR)(PBz₃)₄] (R = ^tBu, 6; CNCy, 7; CNXyl, 8; CNMe, 9) have been prepared and the structures of three of them are described here.