Silver(I) complexes with aryldithiocarboxylates and triphenylphosphine. Crystal and molecular structure of the dinuclear complex [{Ag(S 2C- p-tolyl)PPh 3} 2] and NMR investigation of the mononuclear compounds [{Ag(S 2CAr)(PPh 3} 2] in solution

Abstract

1H, 13C, 31P NMR spectra are reported for the complexes [Ag(S 2CAr)(PPh 3) 2] (Ar=phenyl, o-tolyl, p-tolyl). In solution at room temperature these species are partially dissociated and the phosphine undergoes fast exchange. 31P NMR parameters were obtained from low temperature spectra, 13C and 1H data from room temperature spectra. Overall examination of the spectra shows that no stable species with more than two triphenylphosphine molecules coordinated to one silver atom is detectable, that in phenyl and p-tolyl derivatives the dithiocarboxylato group prefers to be coplanar with the aromatic ring also in solution and that in the AgS 2CAr bonding the covalent character is rather poor. The monophosphine derivatives [{Ag(S 2CAr)PPh 3} 2] (Ar= o-tolyl, p-tolyl) present incongruent solubility. For the complex with Ar= p-tolyl X-ray diffraction methods show an unusual molecular structure, consisting of centrosymmetric species [{Ag(CS 2- p-tolyl)PPh 3} 2], in which the dithioarylate ligand is tridentate; while S(1) bridges two metal centres (2.631(2) and 2.692(3) Å), S(2) is only bonded to one silver atom (2.657(2) Å). Phosphorus atoms from triphenylphosphine (AgP = 2.392(2) Å) complete the distorted tetrahedral arrangement of the silver atoms. The crystals are triclinic, space group P 1 , with a=11.744(3), b=10.862(2), c=9.831(2) Å, α=106.90(2), β=96.51(2), γ=74.54(2)° and Z=1. A total of 3206 symmetry independent reflections above background was measured at room temperature and the structure, solved by Patterson and Fourier methods, was refined by full matrix least-squares to R=0.050.