Phosphine exchange reactions involving cis-[Pt(PPh3)2(Bcat)2] (cat=1,2-O2C6H4) and the oxidative addition of 1,2-B2Cl2(NMe2)2 to Pt0

The reaction between the platinum(II) bis(boryl) complex cis-[Pt(PPh3)(2)(Bcat)(2)] (cat = 1,2-O2C6H4) and the tertiary phosphines PMe3, PEt3, PMe2Ph, PMePh2 and dcpe [1,2-bis(dicyclohexylphosphino)ethane] and the phosphite P(OEt)(3) afforded the new complexes cis-[Pt(PR3)(2)(Bcat)(2)] (PR3 = PMe3, PEt3, PMe2Ph or PMePh2), cis-[Pt(dcpe)-(Bcat)(2)] and cis-[Pt{P(OEt)(3)}(2)(Bcat)(2)]. With PCy3 the mixed phosphine species cis-[Pt(PCy3)(PPh3) (Bcat)(2)] is the major product and was characterised by X-ray crystallography. With P(OMe)(3) reductive elimination of B-2(cat)(2) and the formation of platinum(0) products occurs exclusively whereas with dmpe [1,2-bis(dimethylphosphino)ethane] the only identifiable product is the platinum(II) species [Pt(dmpe)(2)]Cl-2. With dppm [bis(diphenylphosphino)methane] a reaction occurs to give a product assigned the structure cis-[Pt(dppm)(Bcat)(2)] or [Pt-2(dppm)(2)(Bcat)(4)] but two binuclear products were isolated as minor products, namely [Pt-2(PPh3)(mu-dppm)(2)(Bcat)(mu-Bcat)] and [Pt-2(kappa(1)-dppm)-(mu-dppm)(2)(Bcat)(mu-Bcat)]. Both compounds were characterised by X-ray crystallography and shown to contain unusual semi-bridging Beat groups. The reaction between [Pt(PPh3)(2)(eta-C2H4)] and the diborane(4) compound 1,2-B2Cl2(NMe2)(2) is also described which results in B-B bond oxidative addition yielding cis-[Pt(PPh3)(2){BCl(NMe2)}(2)] and a complex to which this bis(boryl) subsequently rearranges, namely trans-[PtCl(PPh3)(2){BCl(NMe2)}]. Both of these complexes were characterised by X-ray crystallography and have geometries typical of cis-bis(boryl) and trans-boryl chloride complexes respectively.