Gold(I) complexes with P=O and P-OH functionalised phosphorus ligands

P-coordination of anionic phosphonite [((RO)-O-2)(RPO)-P-1](-) or phosphite [(RO)(2)PO](-) ligands to (triorganophosphine)gold(I) units leads to neutral molecules with an unsymmetrical P-Au-P' axis and a P=O function. A general synthetic route starts from (R3P)AuMe precursors and the corresponding primary phosphonites ((RO)-O-2)(RP)-P-1(O)H or secondary phosphites (RO)(2)P(O)H, respectively. The gold(I) phosphonites (R3P)AuP(O)R-1(OR2) (1a-d) undergo a ligand redistribution in solution, establishing equilibria that involve ionic isomers of the type [(R3P)(2)Au](+)[Au{P(O)R-1(OR2)}(2)](-) as demonstrated by NMR spectroscopy. In the complexes Ph2P(OH)AuCl (2), Ph2P(OH)AuGeCl3 (3), [Ph2P(OH)](2)Au+X-, with X- = ClO4- (4a), SbF6- (4b), BF4- (4c), TfO- (4d) and (MeO)(2)P(OH)AuCl (5) the phosphinous acid and the phosphorous acid diester, respectively, are coordinated to gold(I) as neutral ligands with a P-OH function, respectively. The combination of the anionic phosphite and neutral ester ligands in the same molecule leads to the formation of compounds [(RO)(2)P(OH)AuP(O)(OR)(2)](n) (6a-c), which oligomerise via cooperative action of hydrogen and aurophilic bonding as determined by single-crystal X-ray diffraction and NMR measurements. The degree of oligomerisation depends largely on the steric effect of the R groups. Compound 6b is a dimer, while compound 6a is a polymer. The crystal structure of the phosphite complex [(Me3P)AuP(O)(OMe)(2)](n). (7) contains a chain of neutral monomeric units associated solely via aurophilic contacts. (C) 2000 Elsevier Science S.A. All rights reserved.