Synthesis and X-ray structural characterization of cobalt(II), copper(II), and silver(I) complexes of triphenylphosphoniopropionate

Four transition-metal carboxylate-like complexes have been synthesized from the reaction of the tertiary phosphine betaine triphenylphosphoniopropionate, Ph3P+(CH2)2CO2−, with Co(ClO4)2· 6H2O, Cu(ClO4)2·6H2O, Cu(BF4)2·xH2O, and AgClO4, respectively, and fully characterized by single-crystal X-ray analysis. [CoPh3P(CH2)2CO24(H2O)2](ClO4)2·2H2O, 1, space groupP¯ l witha=9.195(2),b=13.000(2),c=18.795(3) Å,α=102.52(1),β=90.12(1),γ=109.28(2)° andZ=1; [CuPh3P(CH2)2CO24][Cu2μ -Ph3P(CH2)2CO2 -O,O′4(H2O)2] (ClO4)6· 4H2O, 2, space groupP2l/c witha=14.225(3),b=24.624(6),c=24.297(5) Å,β=94.18(1)°, andZ=2; [CuPh3,P(CH2)2CO2Me2N(CH2)2NMe2(H2O)2](BF4)2,3, space groupP2l/c witha=17.668(2),b=13.454(3),c=15.876(2) Å,β=116.45(1)°, andZ=4; [Ag2Ph3P(CH2)2CO22(ClO4)]2(ClO4)2,4, space groupP¯ l witha=10.925(2),b=13.110(3),c=18.795(3) Å,α=82.93(3),β=87.45(3),γ=67.49(3)°, andZ=2. In complex1, the cobalt(II) atom is located in an inversion center and coordinated by four unidentate betaine ligands and a pair oftrans aqua ligands, and strong hydrogen bonds are formed between the aqua ligands and the pendant oxygen atoms of the betaine ligands. In complex2, mononuclear and dinuclear cations coexist in the asymmetric unit. In the mixed-ligand complex3 the betaine ligand acts in the unidentate coordination mode andN,N,N′,N′-tetramethylethylenediamine (tmen) in the chelate mode. Complex4 contains a discrete centrosymmetric tetranuclear cations in which one pair of betaine ligands act in the bidentate bridging mode and the other in both bidentate and one-atom bridging modes.