Synthesis and characterisation of isomeric cycloaurated complexes derived from the iminophosphorane Ph 3P [dbnd]NC(O)Ph

Abstract

Using different organomercury substrates, two isomeric cycloaurated complexes derived from the stabilised iminophosphorane Ph 3P NC(O)Ph were prepared. Reaction of Ph 3P NC(O)Ph with PhCH 2Mn(CO) 5 gave the manganated precursor (CO) 4Mn(2-C 6H 4C(O)N PPh 3), metallated on the C(O)Ph substituent, which yielded the organomercury complex ClHg(2-C 6H 4C(O)N PPh 3) by reaction with HgCl 2 in methanol. Transmetallation of the mercurated derivative with Me 4N[AuCl 4] gave the cycloaurated iminophosphorane AuCl 2(2-C 6H 4C(O)N PPh 3) with an exo PPh 3 substituent. The endo isomer AuCl 2(2-C 6H 4Ph 2P NC(O)Ph) [aurated on a PPh 3 ring] was obtained by an independent reaction sequence, involving reaction of the diarylmercury precursor Hg(2-C 6H 4P( NC(O)Ph)Ph 2) 2 [prepared from the known compound Hg(2-C 6H 4PPh 2) 2 and PhC(O)N 3] with Me 4N[AuCl 4]. Both of the isomeric iminophosphorane derivatives were structurally characterised, together with the precursors (2-HgClC 6H 4)C(O)N PPh 3 and (CO) 4Mn(2-C 6H 4C(O)N PPh 3). The utility of 31P NMR spectroscopy in monitoring reaction chemistry in this system is described.