Synthesis and characterisation of isomeric cycloaurated complexes derived from the iminophosphorane Ph3PNC(O)Ph

Using different organomercury substrates, two isomeric cycloaurated complexes derived from the stabilised iminophosphorane Ph3PNC(O)Ph were prepared. Reaction of Ph3PNC(O)Ph with PhCH2Mn(CO)5 gave the manganated precursor (CO)4Mn(2-C6H4C(O)NPPh3), metallated on the C(O)Ph substituent, which yielded the organomercury complex ClHg(2-C6H4C(O)NPPh3) by reaction with HgCl2 in methanol. Transmetallation of the mercurated derivative with Me4N[AuCl4] gave the cycloaurated iminophosphorane AuCl2(2-C6H4C(O)NPPh3) with an exo PPh3 substituent. The endo isomer AuCl2(2-C6H4Ph2PNC(O)Ph) [aurated on a PPh3 ring] was obtained by an independent reaction sequence, involving reaction of the diarylmercury precursor Hg(2-C6H4P(NC(O)Ph)Ph2)2 [prepared from the known compound Hg(2-C6H4PPh2)2 and PhC(O)N3] with Me4N[AuCl4]. Both of the isomeric iminophosphorane derivatives were structurally characterised, together with the precursors (2-HgClC6H4)C(O)NPPh3 and (CO)4Mn(2-C6H4C(O)NPPh3). The utility of 31P NMR spectroscopy in monitoring reaction chemistry in this system is described.