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

Abstract

The phosphine chalcogenides Fe[η-C ₅ H ₄ P(E)Ph ₂ ] ₂ (L) [E = nothing (dppf), S (dptpf) or Se (dpspf)] reacted readily with [Cu(MeCN) ₄ ]X (X = BF ₄ , PF ₆ or ClO ₄ ) in CH ₂ Cl ₂ to give quantitatively the monomeric two-co-ordinated complexes [CuL]BF ₄ (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 ¹ H, ³¹ P-{ ¹ H} and ¹⁹ F 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 ^I ₄ 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)°. The Cu–S bond distances [2.144(5) and 2.140(5) Å] 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°) and staggered by 16.1°.