Heterometallic cuboidal clusters M3M′Q4 (M = Mo, W; M′= Sn, Pb, As, Sb; Q = S, Se):: From coordination compounds to supramolecular adducts

Reactions of the incomplete cuboidal clusters [M(3)Q(4)(acaC)(3)(PY)(3)](+) (M = Mo, W; Q = S, Se) with group 14 and 15 metal complexes with the S(2)p(0) electronic configuration (AsPh3, SbPh3, SbCl3, Sbl(3), Pbl(3)(-), SnCl3-) led to heterometal incorporation with the formation of cuboidal clusters of the type [M-3(EX3)Q(4)(acac)(3)(py)(3)](n+) (n = 0 for Sn, Pb; n = 1 for As, Sb), whose structures were determined by X-ray diffraction. The cuboidal clusters can be described as complexes of the cluster tridentate ligand [M(3)Q(4)(acac)(3)(PY)(3)](+) (mu(2)-chalcogen atoms as donors) with the EX3, where the E atom attains a distorted octahedral coordination. Analysis based on the bond distances E-Q gives the following sequence of affinity: As < Sb; Pb < Sn approximate to Sb; SbPh3 < Sbl(3) approximate to SbCl3; W3S4 < W3Se4. Interaction energies at the gas phase between [W(3)Q(4)(acac)(3)(py)(3)](+) (Q = S, Se) and SbX3 (X = 1, Ph) were computed at the DFT level (BP86/TZP). The magnitude of the interaction depends strongly on the substituents at Sb, and the replacement of iodine by the phenyl group decreases the interaction energy from -9.21 to -2.70 kcal/mol and from -12.73 to -3.85 kcal/mol for the W3SbS4 and W3SbSe4 cores, respectively.