Copper(I) and silver(I) tertiary phosphines complexes: Synthesis, X-ray structures and spectroscopic characterization Muhammad Altaf * , Helen Stoeckli-Evans Institute of Physics, University of Neuchâtel, rue Emile-Argand 11, CH-2009 Neuchâtel, Switzerland article info Article history: Received 24 October 2009 Received in revised form 6 April 2010 Accepted 18 April 2010 Available online 28 April 2010 Keywords: Tertiary phosphines Copper(I) and silver(I) complexes NMR spectroscopy X-ray structure Phosphorous donor ligand abstract Six new complexes, [Cu 4 I 4 (PPh 2 Cy) 4 ]2H 2 O(1), [CuI(PPhCy 2 ) 2 ](2), [CuCl(PPhCy 2 ) 2 ](3), and [CuBr(PPh 3 ) 3 ] CH 3 CN (4), [Ag(PPhCy 2 ) 2 (NO 3 )] (5), [Ag(PCy 3 )(NO 3 )] 2 (6) [where Ph = phenyl, Cy = cyclohexyl], have been synthesized and structurally characterized by X-ray diffraction, IR absorption spectra and NMR spectro- scopic studies (except complex 4). The X-ray diffraction analysis of complex (1), pseudo polymorph of complex [Cu 4 I 4 (PPh 2 Cy) 4 ], reveals a stella quadrangula structure. The four corners of the cube are occu- pied by copper(I) atoms and four I atoms are present at the alternative corners of the cube, further more the copper(I) atoms are coordinated to a monodentate tertiary phosphine. Complexes (2) and (3) are iso- structural with trigonal planar geometry around the copper(I) atom. The crystal structure of complex (4) is a pseudo polymorph of complex [CuBr(PPh 3 ) 3 ] and the geometrical environment around the copper(I) centre is distorted tetrahedral. In the Ag I complexes (5) and (6), the central metal atoms have pseudo tet- rahedral and trigonal planar geometry, respectively. Spectroscopic and microanalysis results are consis- tent with the single crystal X-ray diffraction studies. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction Our interest in the Cu I and Ag I compounds with monodentate tertiary phosphine ligands; is to explore the structural chemistry of these complexes and their mixed ligand multi-dimensional complexes of versatile architectures. Reaction of coin metal(I) salts with monodentate tertiary phosphine bases yielded an array of two, three, and four coordinated complexes with diverse structural properties that are determined by the specific choice of the phos- phine ligand and to a lesser extent, by the choice of counter ions [1]. Neutral phosphine and amine ligands form mono- or multi-nu- clear complexes with copper(I) and copper(II) salts, in which the coordination number ranges from two to four [2–10]. The greatest range of structural types has been found for the case of tertiary phosphines, of which the most extensively studied is triphenyl phosphine and to a lesser extent tricyclohexyl phosphine [11–16]. The geometry around the copper(I) atom in complexes with ter- tiary phosphine ligands depends on the stoichiometric ratio of the metal salt and ligand used, as well as the solvent of crystallization. Thus for a compound of 1:1 stoichiometry monomer, dimer and tetramer complexes are possible with general formulae of [MX(PR 3 )], [M 2 X 2 (PR 3 ) 2 ] and [M 4 X 4 (PR 3 ) 4 ] (where M = Ag and Cu. R = phenyl, alkyl, aryl or cyclohexyl groups) [1,17–20]. Whereas, the compounds with stoichiometry 1:1.5 are dimers [15,16], and compounds with stoichiometry 1:2 and 1:3 are monomers and dimers with tetrahedral and trigonal planar geometries, respec- tively, around the metal centre [11,22–24]. The complexes of gen- eral formula [M 4 X 4 (PR 3 ) 4 ] (X = Cl, Br or I) have pseudo cubane-like structures [10,25,26]. These types of structures can be described as two interpenetrating tetrahedra of four metals (M) and four triply bridging halides (anions) situated on alternative corners of a dis- torted cube with each metal atom being further coordinated to one terminal monodentate ligand [17]. Frequently a non-system- atic deviation of the cubane core from the idealized tetrahedral geometry is observed for cubane-like metal clusters [27–29]. Tertiary phosphine complexes of silver(I) of the type [AgXL n ], where L = tertiary phosphine; n = 1–4; X = coordinating or non- coordinating anion, were first prepared as early as 1937 [30–38]. The reaction of silver(I) salts with monodentate tertiary phosphines in a 1:2 stoichiometric ratio generally results in the formation of either monomeric [AgX(PR 3 ) 2 ]/[Ag(PR 3 ) 2 ]X [39–51], or dimeric complexes [AgX(PR 3 ) 2 ] 2 [51–54], depending on the donor proper- ties of the phosphine ligand, the bulkiness of this ligand, and the do- nor properties of the anion. These complexes show a diversity of structural types and several reviews on this topic have been pub- lished [31–38]. The metal centre in the majority of the neutral [AgX(PR 3 ) 2 ] and [AgX(PR 3 ) 2 ] 2 complexes are predominantly four coordinate, with the anion acting as either a bi-dentate chelating li- gand or as a bridging ligand. Two or three coordination have been found only in circumstances where the anion is a weak donor or the substituents on the phosphine ligand are bulky [43,46–51]. 0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ica.2010.04.031 * Corresponding author. Tel.: +41 32 718 24 00; fax: +41 32 718 25 11. E-mail address: muhammad.altaf@unine.ch (M. Altaf). Inorganica Chimica Acta 363 (2010) 2567–2573 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica