The Polymeric Structure of Aquacadmium Bisnicotinate

Abstract

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

Syntheses, structures and photoluminescent properties of two metal-organic complexes assembled with a new polycarboxylate ligand

“…Another Cd(II) center (Cd3) is bound by three L 3− ligands through their oxygen atoms, and two water molecules. The distances of Cd1-O are range from 2.168 to 2.662 Å, being comparable to those reported in the related complex [12]. The bond angles of O-Cd-O are in the range of 54.36(14)°to 162.91(14)°(the neighboring atoms range).…”

New thallium(III) chloride complexes with pyridine carboxylic acids: from molecular compounds to supramolecular associations

“…A survey of the reported molecular structure determinations for metal complexes reveals that the O,Nmonometallic biconnective (bidentate) (Scheme 1, structures I and II) is the most usual coordination pattern for the deprotonated form of the picolinic (Hpic) and 3-hydroxypicolinic (H3hpic) acids [1,2,3,4]. Nicotinic (Hnic) and isonicotinic (Hinic) acids were found to coordinate: (i) as unidentate, neutral ligands only through the pyridyl nitrogen atom (Scheme 1, structures IIIa and IVa) [5,6], (ii ) as O,O-bimetallic biconnective (bridging) ligands (Scheme 1, structures IIIb and IVb) [7,8], and (iii ) as O,O; N -bimetallic triconnective (tridentate) groups (Scheme 1, structures IIIc and IVc) [9,10]. The presence of the carboxylate group as substituent in position 2 of the pyridine ring usually leads to O,N -monometallic biconnective (chelate) coordination, while substitution in position 3 or 4 promotes the formation of supramolecular associations through bridging ligands.…”

Crystal Structure and Characterization of the Dinuclear Cd(II) Complex [Cd(H2O)2(ο-HOC6H4COO)2]2

“…The complex has an inversion centre located at the middle of the dimer. [5]. However, both of these carboxylates are bound asymmetrically with one Cd-O bond length somewhat longer than the other [6].…”