Silver (I) complexes with heterocyclic thiones and tertiary phosphines as ligands part 2. Mononuclear complexes of silver(I) nitrate. The crystal structures of [Ag(PPh3)2(pytH)2]NO3 and [Ag(PPh3)2(pymtH)]NO3

Article abstract of DOI:10.1016/S0020-1693(96)05172-9

The preparation and characterization of mononuclear silver(I) nitrate complexes with various heterocyclic thiones (pytH = pyridine-2-thione, pymtH = pyrimidine-2-thione, quin2tH = quinoline-2-thione, tzdtH = thiazolidine-2-thione, mbzimtH₂ = N-methyl-benzimidazoline-2-thione, pur6tH = purine-6-thione) and triphenylphosphine as ligands are described. The X-ray determination of the crystal structures of [Ag(PPh₃)₂(pytH)₂]NO₃ (I) and [Ag(PPh₃)₂(pymtH)]NO₃ (II) is also reported. Compound I crystallizes in the monoclinic system, space group P2₁/c, with a = 12.588(3), b = 18.234(5), c = 18.527(5) A, β = 96.29(2)°, V = 4227 A³ and Z = 4, while crystals of II are triclinic, space group P1, with a = 10.084(2), b = 13.508(3), c = 14.326(3) A, α = 77.43(2), β = 78.77(2), γ = 79.14(2)°, V = 1846 A₃ and Z = 2. The coordination geometry about the silver atom is distorted tetrahedral in I, with one nitrate ion bridging two adjacent complex molecules via strong hydrogen bonds with the thione NH groups. The structure of II consists of almost trigonal-planar AgP₂S units and strongly distorted nitrate ions hydrogen bonded to the protonated nitrogen atoms of the heterocyclic thione ligands. The electronic factors imposing the above difference in coordinating behavior are investigated by means of semi-empirical molecular orbital considerations.