The synthesis of new metal complexes containing the keto phosphine ligands R 1 2 PCH 2 C- 2) was obtained (PkO = η 2 (P,O)-chelated ligand). Reaction of 2 with TlPF 6 afforded the cationic compound [Rh(PkO) 2 ][PF 6 ] (3). The X-ray crystal structure determination of 3‚H 2 O shows a distorted-square-planar geometry with the two phosphorus atoms (and oxygen atoms) in cis positions. Treatment of [RhCl(CO)(PPh 3 ) 2 ] with 1 equiv of L gave [RhCl(CO)(P∼O)(PPh 3 )] (5). In the presence of TlPF 6 the cationic complex [Rh(CO)(PkO)(PPh 3 )][PF 6 ] (6) was obtained. The X-ray crystal structure determination of 6 shows a slightly distorted square planar geometry with the two phosphorus atoms in trans positions. The reaction of 5 or 6 with 1 equiv of NaOMe produced the phosphino enolate

reflections. The structure consists of a PF~-anion in a general position and two ferrocenium cations lying on independent crystallographic inversion centres. This imposed symmetry leads to the cyclopentadienyl rings being ideally staggered (twist angle 36 ° from eclipsed conformation).

Reaction of RNHC(S)PPh2NPPh2C(S)NR (HRSNS; R = Me, Et) with M(I) (M = Cu, Ag, Au) salts afforded zwitterionic complexes of the general formula [M(RSNS)] (M = Cu, Ag, Au). The ligand was found in the solid state in S,S-kappa2 and S,N,S-kappa3 coordination fashions. [Cu(RSNS)] and [Ag(RSNS)] can be used as metalloligand building blocks for the assembly of pentanuclear multizwitterionic Cu5, Cu3Ag2 and Ag5 core clusters of the general formula [M'2{M(RSNS)}3]2+ (M = Cu, M' = Cu, Ag; M = M' = Ag) upon reaction with suitable M' salts. The crystal structures of the most significant compounds are reported herein. Compound [Ag2{Ag(RSNS)}2(OTf)2] was also isolated and structurally characterized, representing a model for the intermediate species of the aforementioned assembly.