Bonding ability of 1,1'-bis(diphenylthiophosphoryl)ferrocene (dptpf) and its selenium analogue towards copper(I). Crystal structure of [Cu(dptpf)]BF4

The phosphine chalcogenides Fe[eta-C5H4P(E)Ph(2)](2) (L) [E = nothing (dppf), S (dptpf) or Se (dpspf)] reacted readily with [Cu(MeCN)(4)]X (X = BF4, PF6 or ClO4) in CH2Cl2 to give quantitatively the monomeric two-co ordinated complexes [CuL]BF4 (E = S 1 or Se 2) or polynuclear three-co-ordinated derivatives analysing as [CuL(1.5)]X (E = S 3 or Se 4), depending on the ligand to copper molar ratio. The complexes have been characterized by multinuclear NMR spectroscopy. Complexes 3 and 4 reversibly dissociate in solution, as was evident from the concentration- and temperature-dependent NMR spectra. The low-temperature H-1, P-31-{H-1} and F-19 NMR spectra are interpreted in terms of a tetranuclear structure in which each copper atom is trigonally bonded by bridging L ligands and one anion molecule is trapped inside the tetrahedral Cu-4(I) cage. Single-crystal X-ray structure determinations were performed for the two diphosphine chalcogenides and complex 1. The structure of 1 shows a slightly distorted linear two-co-ordination geometry around the copper atom with an S(1)-Cu-S(2) angle of 171.5(2)degrees. The Cu-S bond distances [2.144(5) and 2.140(5) Angstrom] and the Cu-S-P angles [100.8(2) and 105.5(2)] point towards a substantially sp(3) hybridization of the sulfur atoms. In the ferrocene moiety the cyclopentadienyl rings are virtually parallel (dihedral angle between the two planes 6.5 degrees) and staggered by 16.1 degrees.