Cluster core controlled reactions of substitution of terminal bromide ligands by triphenylphosphine in octahedral rhenium chalcobromide complexes

Reactions of rhenium chalcobromides Cs-4[{Re-6(mu(3)-S)(8)}Br-6]center dot 2H(2)O, Cs-3[{Re-6(mu(3)-Se)(8)}Br-6]center dot 2H(2)O, Cs-3[{Re-6(mu(3)-Q)(7)(mu(3)-Br)}Br-6]center dot H2O (Q = S, Se), and K-2[{Re-6(mu(3)-S)(6)(mu(3)-Br)(2)}Br-6] with molten triphenylphosphine (PPh3) have resulted in a family of novel molecular hybrid inorganic-organic cluster compounds. Six octahedral rhenium cluster complexes containing PPh3 ligands with general formula [{Re-6(mu(3)-Q)(8-n)(mu(3)-Br)(n)}(PPh3)(4-n)Brn+2] (Q = S, n = 0, 1, 2; Q = Se, n = 0, 1) have been synthesized and characterized by X-ray single-crystal diffraction and elemental analyses, P-31{H-1} NMR, luminescent measurements, and quantum-chemical calculations. It was found that the number of terminal PPh3 ligands in the complexes is controlled by the composition and consequently by the charge of the cluster core {Re(6)Q(8-n)Br(n)}(n+2). In crystal structures of the complexes with mixed chalcogen/bromine ligands in the cluster core all positions of a cube [Q(8-n)Br(n)] are ordered and occupied exclusively by Q or Br atoms. Luminescence characteristics of the compounds trans-[{Re(6)Q(8)}(PPh3)(4)Br-2] and fac-[{Re6Se7Br}(PPh3)(3)Br-3] (Q = S, Se) have been investigated in CH2Cl2 solution and the broad emission spectra in the range of 600-850 nm were observed.