Cu[sub 3](μ[sup 2]-Cl)[sub 3] and Ag[sub 3](μ[sup 2]-Cl)[sub 3] Complexes Supported by Tetradentate Trisphosphino-stibine and -bismuthine Ligands: Structural Evidence for Triply Bridging Heavy Pnictines.

The tetradentate stibine and bismuthine ligands (o-([sup i]Pr[sub 2]P)C[sub 6]H[sub 4])[sub 3]Sb (L[sup P3][sub Sb]) and (o-([sup i]Pr[sub 2]P)C[sub 6]H[sub 4])[sub 3]Bi (L[sup P3][sub Bi]) react with CuCl and AgCl in THF at room temperature to afford (o-([sup i]Pr[sub 2]P)C[sub 6]H[sub 4])[sub 3]SbCu[sub 3](μ[sub 2]-Cl)[sub 3] (1), (o-([sup i]Pr[sub 2]P)C[sub 6]H[sub 4])[sub 3]SbAg[sub 3](μ[sub 2]-Cl)[sub 3] (2), (o-([sup i]Pr[sub 2]P)C[sub 6]H[sub 4])[sub 3]BiCu[sub 3](μ[sub 2]-Cl)3 (3), and (o-([sup i]Pr[sub 2]P)C[sub 6]H[sub 4])[sub 3]BiAg[sub 3](μ[sub 2]-Cl)[sub 3] (4), respectively. These complexes, which have been fully characterised, feature a central M[sub 3](μ[sub 2]-Cl)[sub 3] cluster (M = Cu or Ag) supported by coordination of a L[sup P3][sub Sb]- or LL[sup P3][sub Bi]-phosphino group to each group 11 metal ion. The heavy pnictogen atom (Pn) interacts simultaneously with the three group 11 metal ions of the M[sub 3](μ[sub 2]-Cl)3 cluster leading to formation of a tetrahedral PnM[sub 3] core. Bonding analysis using the Natural Bond Orbital method indicates the presence of a four-centre two-electron Pn → M[sub 3] interaction whose strength is the highest in 1 and the lowest in 4. The triply bridging bonding mode of the stibine and bismuthine ligands observed in these complexes is, to our knowledge, unprecedented. We also note that the central M[sub 3](μ[sub 2]-Cl)[sub 3] clusters found in these complexes are related to the cyclo-trimers observed in vapours of CuCl and AgCl. [ABSTRACT FROM AUTHOR]