Iridium(III) complexes of diphenylphosphinous acid and secondary phosphites
Abstract
Treating [{IrCl(1,5-C8H12)}2] with PPh2Cl and water gives [IrHCl(1,5-C8H12){(PPh2O)2H}](1). Diene dissociation readily occurs; in the absence of added ligand polymeric materials are probably formed, but in the presence of bidentate ligands, complexes [IrHCl(L–L){(PPh2O)2H}][L–L = Ph2AsCH2CH2AsPh2, PhSCH2CH2SPh, or Ph2PCH2CH2PPh2] are formed. Reaction with BF3 and HBF4 leads to the respective formation of [IrHCl(L–L){(PPh2O)2BF2}](L–L = Ph2AsCH2CH2AsPh2 or PhSCH2CH2SPh) and [IrHCl(L–L){(PPh2(OH)}2]BF4(L–L = Ph2AsCH2CH2AsPh2 or PhSCH2CH2SPh). The latter compounds readily lose HF to give the BF2-capped products. Structural characterisation is by i.r.,1H, and 31P-{1H} n.m.r. spectroscopy. A heterobimetallic compound [PPh3(CH2Ph)][(Et2NCS2)Pt(µ-PPh2S)2IrHCl{(PPh2O)2H}] has been isolated from [PPh3(CH2Ph)][Pt(S2CNEt2)(PPh2S)2] and [IrHCl(1,5-C8H12){(PPh2O)2H}] and heterobimetallic and trimetallic compounds can be prepared by substitution of the phosphinous acid proton by a second metal ion. Consequently, compounds [IrHCl(Ph2AsCH2CH2AsPh2)(µ-PPh2O)2M(acac)](acac = acetylacetonate) and [{IrHCl(Ph2AsCH2CH2AsPh2)(PPh2O)2}2M](M = VO2+ or Co2+) have been isolated. Treating [Ir(MeCN)(CO)(PPh3)2]ClO4 with P(OMe)2(O)H yields [IrH(CO)(PPh3)2{[P(OMe)2O]2H}]ClO4. Finally, solution addition of P(OR)2(O)H (R = Me, Et, or Ph) and PPh2(O)H to [IrCl(CO)(PPh3)2] yields unstable hydrides whose composition and stereochemistry have been deduced in situ using a combination of 1H and 31P-{1H} n.m.r. spectroscopy.