The Coordination Behaviour of Ferrocene-based Pyridylphosphine Ligands towards AgI and AuI

The reaction of the P,N-ligands [Fe(C5H4-PPh2)(C5H4-2-py)] (1) (2-py = pyrid-2-yl), [Fe(C5H4-PPh2)(C5H4-CH2-2-py)] (2) and [Fe(C5H4-PPh2)(C5H4-3-py)] (3) (3-py = pyrid-3-yl) with Ag[BF4] in a 1:1 stoichiometric ratio afforded complexes of the type [Ag(L)][BF4] (L = 1-3), which were structurally characterised by X-ray diffraction. Two structure types were observed in the solid state, viz. coordination polymer (L = 1, 2) and cyclic dimer (L = 2, 3). The reaction of 1-3 with one equivalent of [AuCl(tht)] (tht = tetrahydrothiophene) afforded complexes of the type [AuCl(L-kappa P)] (L = 1-3), whose crystal structures were determined by X-ray diffraction. Their reactions with one equivalent of Ag[BF4] gave products of the general composition [Au(L)][BF4]; of these the cyclic dimer {[Au(mu-1)][BF4]}(2) was structurally characterised by X-ray diffraction. The P,N,P-ligand C5H3N-2,6-(fcPPh(2))(2) (4, fc = 1,1'-ferrocenediyl) was synthesised by Negishi cross-coupling of Ph(2)PfcZnCl with 2,6-dibromopyridine. Its crystal structure was determined by X-ray diffraction. The reaction of 4 with two equivalents of [AuCl(tht)] afforded the dinuclear gold(I) complex [(AuCl)(2)(mu-4-kappa P-2,P)]. The mononuclear gold(I) complex [Au(4-kappa P-2,P)][SbF6] was obtained in a one-pot reaction of 4 with one equivalent of [AuCl(tht)] and subsequently with one equivalent of Ag[SbF6]; it contains 4 in a trans-chelating binding mode, as revealed by a crystal structure determination.