Synthesis of phosphinoferrocene amides and thioamides from carbamoyl chlorides and the structural chemistry of Group 11 metal complexes with these mixed-donor ligands

Abstract

The reaction of in situ generated 1′-(diphenylphosphino)-1-lithioferrocene with carbamoyl chlorides, ClC(E)NMe₂, affords the corresponding (thio)amides, Ph₂PfcC(E)NMe₂ (E = O (2), S (3); fc = ferrocene-1,1′-diyl). These compounds as well as their analogues, Ph₂PfcC(O)NHMe (4) and Ph₂PfcC(O)NH₂ (5), prepared from 1′-(diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) were studied as ligands for the Group 11 metal ions. In the reactions with [Cu(MeCN)₄][BF₄], the amides give rise to bis-chelate complexes of the type [Cu(L-κ²O,P)₂][BF₄]. Similar products, [Ag(L-κ²O,P)₂]ClO₄, are obtained from silver(I) perchlorate and 2, 4 or 5. In contrast, the reaction of AgClO₄ with 3 produces a unique molecular dimer [Ag(3)(ClO₄-κO)]₂, where the metal centres are bridged by the sulfur atoms of the P,S-chelating thioamides. The reactions of 2–5 with [AuCl(tht)] (tht = tetrahydrothiophene) afford the expected gold(I)–phosphine complexes, [AuCl(L-κP)], containing uncoordinated (thio)amide moieties. Hemilabile coordination of the phosphinoamide ligands in complexes with the soft Group 11 metal ions is established by the crystal structure of a solvento complex, [Cu(5-κ²O,P)(5-κP)(CHCl₃-κCl)][BF₄], which was isolated serendipitously during an attempted crystallisation of [Cu(5-κ²O,P)₂][BF₄]. All of the compounds are characterised by spectroscopic methods, and the structures of several representatives of both the free phosphinoamides and their complexes are determined by X-ray diffraction analysis and further studied by DFT calculations and cyclic voltammetry.