Variable coordination modes for 1,1′-bis(diphenylphosphino)ferrocene (dppf) mono- and di-chalcogenides or -oxides (dppfE and dppfE2;: E = O, S or Se) in copper(I) complexes.: Crystal structure of [{Cu(dppf)}2(μ-dppfS2)](BF4)2 and [Cu(dppfSe)2]BF4

Reaction of [Cu(MeCN)(4)]BF4 with the phosphine Fe[eta(5)-C5H4PPh2](2) (dppf) and its disulfide (dppfS(2)) sequentially in chlorinated solvents led to the dinuclear tricoordinate complex [{Cu(dppf-P,P')}(2)(mu-dppfS(2)-S,S')] (BF4)(2) (1), whereas reaction of the copper reagent with dppf and its diselenide (dppfSe(2)) gave the bis-chelate dppf-monoselenide compound [Cu(dppfSe-P,Se)(2)] BF4 (2). Similarly, the E = O or S relevant complexes [Cu(dppfE-P,E)(2)] BF4 were obtained by reaction of the copper(I) precursor with the dppf-monoderivatives [eta(5)C(5)H(4)PPh(2)] Fe[eta(5)-C5H4P(E) Ph-2] (dppfE). The complexes have been characterized by H-1 and P-31 NMR spectroscopy. Single-crystal X-ray structure determinations were performed for complexes 1 and 2. Complex 1 crystallizes as CHCl3, (1a) or CHBr3, (Ib) monosolvates. The cation of 1 is exactly centrosymmetric and shows a distorted trigonal planar coordination at copper with a P-Cu-P angle of 115.7(1)degrees and the S-Cu-P angles of 138.6(1) and 104.3(6)degrees, as mean values from la and Ib, in complex 2 the coordination geometry around the metal atom is markedly distorted tetrahedral with the two dppfSe moieties acting as chelating ligands with bite angles of 111.5(2) and 116,8(2)degrees, The Se (1)-Cu-Se(2) angle (103.4(2)degrees) approaches the value for tetrahedral geometry, while the remaining angles differ significantly from the ideal value ranging from 96.1(2) to 121.9(3)degrees. The Cu-Se-P angles (124.5(2) and 132.9(2)degrees) point towards a substantially sp(2) hybridization of the selenium atom. (C) 1998 Elsevier Science S.A. All rights reserved.