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)(PBz 3)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 [Pd 2(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.