The title compound, poly[aquacadmium-bis(#-nicotinato-mN:~O,t~O')], [Cd(C6H4NO2)2(H20)], consists of a polymeric network in which each nicotinate acts as a bidentate chelating ligand towards one Cd atom through its carboxylate group while simultaneously binding to a second Cd atom through its pyridine N atom. Cd has approximate pentagonal bipyramidal coordination geometry. Water acts as a ligand; it is also involved in hydrogen bonding to nearby carboxylate O atoms, contributing further to the polymeric network interactions.
CommentThe structure of the title compound, (I), was determined as part of an investigation of the structural chemistry of carboxylate complexes of Group 12 metals. It is polymeric, with the nicotinate ligands binding through their N atoms and carboxylate functional groups. Each Cd atom is coordinated by four different nicotinate ligands, two through their N atoms and two in a chelating fashion through their carboxylate groups. Both these carboxylates are bound asymmetrically, with one Cd--O bond considerably longer than the other. The presence of one water ligand makes each Cd atom seven-coordinate. The coordination geometry can best be described as approximately pentagonal bipyramidal, with the carboxylates and one N atom in the equatorial plane (r.m.s. deviation for the five ligating atoms = 0.101 A; deviation of Cd from the mean plane = 0.163 A), and with the second N atom and the water ligand in axial positions.
(I)The two crystallographically independent nicotinate ligands both show deviations from planarity, consisting mainly of a twist in the carboxylate group about the C--C bond out of the aromatic ring plane. The dihedral
(C7HsN2S2)2 [Pt(C4N2S2)2] AND [(C7I"LICIN2S2)2CI][Pt(C4N2 S2)2]Acta Cryst. (1994 ÷ cation is antibonding with respect to both the S--N and S--S bonds; consequently, charge-transfer interactions between the anions and cations in these stacked structures take place at the expense of S--N and S--S bonding within the cations. These S--N and S--S bonds are observed to be longer than in salts without such interactions, for example [PhCNSSlq][AsF6] (Scholz, Roesky, Schimkowiak & Noltemeyer, 1989). However, in some salts, such as the chloride, interactions in the plane of the cation are found ; these involve a higher-energy molecular orbital of different symmetry, resulting in a shortening of the cation bonds through a net three-centre bonding interaction.As an extension of this work, we have examined other salts containing soft anions, with the aim of enhancing these structurally influential secondary interactions. We report here structures containing [Pt(mnt)2] n-anions (n = 2 and 1) with formal Pt n and Pt m oxidation states, respectively.The asymmetric unit of (1) consists of a complete cation, the Pt and one ligand of the anion. The asymmetric unit of (2) (2)]. In the anions, the PtS4 unit is strictly planar in (1) and in some of the anions of (2), with Pt on an inversion centre; the crystallographically unconstrained anion in (2) has an r.m.s. deviation of 0.039 A, for the PtS4 atoms from their mean plane. The r.m.s, deviations for the complete anions are 0.064 ~, in (1) and 0.092, 0.041 and 0.030 A, in (2).In each complex anion the coordination geometry of Pt is essentially undistorted square planar, with SwPt--S angles deviating by less than 1 ° from the ideal 90 °. The
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.