Phosphine exchange reactions involving cis-[Pt(PPh_3)_2(Bcat)_2] (cat = 1, 2-O_2C_6H_4) and the oxidative addition of 1, 2-B_2Cl(NMe_2)_2 to Pt~0

摘要

The reaction between the platinum (II) bis (boryl) complex cis-[Pt(PPh_3)_2(Bcat)_2] (cat = 1, 2-O_2C_6H_4) and the tertiary phosphine PMe_3, PEt_3, PMe_2Ph, PMePH_2 and dcpe [1, 2-bis (dicyclohexylphosphino) ethane] and the phosphite P(OEt)_3 afforded the new complexes cis-[Pt(PR_3)_2(Bcat)_2] (PR_3=PMe_3, PEt_3, PMe_2Ph or PMePH_2), cis-[Pt(dcpe)(Bcat)_2] and cis-[Pt{P(OEt)_3}_2(Bcat)_2]. With PCy_3 the mixed phosphine species cis-[Pt(PCy_3)(PPh_3)(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(dppm)_2(Bcat)_4] but two binuclear products were isolated as minor products, namely [Pt(PPh_3)(#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 Bcat groups. The reaction between [Pt(PPh_3)_2(#eta#-C_2H_4)] and the diborane (4) compound 1, 2-B_2Cl_2 (NMe_2)_2 is also described which results in B-B bond oxidative addition yielding cis-[Pt(PPh_3)_2{BCl(NMe_2)}_2] and a complex to which this bis (boryl) subsequently rearranges, namely trans-[PtCl(PPh_3)_2{BCl(NMe_2)}]. Both of these complexes were characterised by X-ray crystallography and have geometries typical of cis-bis(boryl) and trans-boryl chloride complexes respectively.