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.