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, Ph(2)PfcC(E) NMe2 (E = O (2), S (3); fc = ferrocene-1,1'-diyl). These compounds as well as their analogues, Ph(2)PfcC(O) NHMe (4) and Ph(2)PfcC(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-kappa O-2, P)(2)][BF4]. Similar products, [Ag(L-kappa O-2, 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-kappa O)](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-kappa P)], 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-kappa O-2, P)(5-kappa P)(CHCl3-kappa Cl)][BF4], which was isolated serendipitously during an attempted crystallisation of [Cu(5-kappa O-2, 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.