Yasunori Muranishi

Aqua­bis­(quinoline-2-carboxyl­ato-κ2N,O)­zinc(II)

In the title compound, [Zn(C10H7NO3)2(H2O)], the Zn atom is pentacoordinated and has a square pyramidal geometry. The Zn atom is coordinated by two N and two O atoms of the two organic ligands, forming the square plane. One aqua O atom occupies the vertex of the square pyramid. The N and O atoms of the ligands lie in trans positions with respect to each other.

8-Hydroxyquinaldinic acid and its nickel(II) complex

The molecules of 8-hydroxyquinolinium-2-carboxylate, C(10)H(7)NO(3), have a planar structure, in which the carboxyl group is ionized and the ring N atom is protonated. The derived nickel(II) complex, bis(8-hydroxyquinoline-2-carboxylato-kappa(3)O(2),N,O(8))nickel(II) trihydrate, [Ni(C(10)H(6)NO(3))(2)].3H(2)O, contains an octahedral central Ni(II) ion coordinated by the hydroxyl O atom, the ring N atom and the carboxylate O atom of each of the two tridentate ligands, with a perpendicular orientation of the quinoline rings.

Cobalt(II), nickel(II) and copper(II) complexes of isoquinoline-3-carboxylate.

The crystal structures of the title complexes, namely trans-bis(isoquinoline-3-carboxylato-kappa2N,O)bis(methanol-kappaO)cobalt(II), [Co(C10H6NO2)2(CH3OH)2], and the corresponding nickel(II) and copper(II) complexes, [Ni(C10H6NO2)2(CH3OH)2] and [Cu(C10H6NO2)2(CH3OH)2], are isomorphous and contain metal ions at centres of inversion. The three compounds have the same distorted octahedral coordination geometry, and each metal ion is bonded by two quinoline N atoms, two carboxylate O atoms and two methanol O atoms. Two isoquinoline-3-carboxylate ligands lie in trans positions, forming the equatorial plane, and the two methanol ligands occupy the axial positions. The complex molecules are linked together by O-H...O hydrogen bonds between the methanol ligands and neighbouring carboxylate groups.

Cobalt(II) and nickel(II) complexes of quinoline-2-carboxylate.

The title complexes, trans-diaquabis(quinoline-2-carboxylato-kappa(2)N,O)cobalt(II)-water-methanol (1/2/2), [Co(C(10)H(6)NO(2))(2)(H(2)O)(2)].2CH(4)O.2H(2)O, and trans-diaquabis(quinoline-2-carboxylato-kappa(2)N,O)nickel(II)-water-methanol (1/2/2), [Ni(C(10)H(6)NO(2))(2)(H(2)O)(2)].2CH(4)O.2H(2)O, are isomorphous and contain Co(II) and Ni(II) ions at centers of inversion. Both complexes have the same distorted octahedral coordination geometry, and each metal ion is coordinated by two quinoline N atoms, two carboxylate O atoms and two water O atoms. The quinoline-2-carboxylate ligands lie in trans positions with respect to one another, forming the equatorial plane, with the two water ligands occupying the axial positions. The complex molecules are linked together by hydrogen bonding involving a series of ring patterns which include the uncoordinated water and methanol molecules.

5-n-Butylpyridine-2-carboxylate-copper(II) and -iron(III) complexes.

In trans-bis(5-n-butylpyridine-2-carboxylato-kappa(2)N,O)bis(methanol-kappaO)copper(II), [Cu(C(10)H(12)NO(2))(2)(CH(4)O)(2)], the Cu atom lies on a centre of symmetry and has a distorted octahedral coordination. The Cu-O(methanol) bond length in the axial direction is 2.596 (3) A, which is much longer than the Cu-O(carboxylate) and Cu-N distances in the equatorial plane [1.952 (2) and 1.977 (2) A, respectively]. In mer-tris(5-n-butylpyridine-2-carboxylato-kappa(2)N,O)iron(III), [Fe(C(10)H(12)NO(2))(3)], the Fe atom also has a distorted octahedral geometry, with Fe-O and Fe-N bond-length ranges of 1.949 (4)-1.970 (4) and 2.116 (5)-2.161 (5) A, respectively. Both crystals are stabilized by stacking interactions of the 5-n-butylpyridine-2-carboxylate ligand, although hydrogen bonds also contribute to the stabilization of the copper(II) complex.

(1,2‐Benzene­diolato‐κ2O,O′)(1,10‐phenanthroline‐κ2N,N′)­palladium(II) dihydrate

In the mononuclear catecholate complex, [Pd(C6H4O2)(C12H8N2)]·2H2O, the PdII has a distorted cis square-planar four-coordinate geometry. It is bonded to two O atoms of a bidentate catecholate dianion and two N atoms of the bidentate phenanthroline. The overall conformation of the complex including catechol and phenanthroline rings is almost planar.

Cobalt(II) and nickel(II) complexes of isoquinoline-1-carboxylate

trans-Diaquabis(isoquinoline-1-carboxylato-kappa(2)N,O)cobalt(II) dihydrate, [Co(C(10)H(6)NO(2))(2)(H(2)O)(2)].2H(2)O, and trans-diaquabis(isoquinoline-1-carboxylato-kappa(2)N,O)nickel(II) dihydrate, [Ni(C(10)H(6)NO(2))(2)(H(2)O)(2)].2H(2)O, contain the same isoquinoline ligand, with both metal atoms residing on a centre of symmetry and having the same distorted octahedral coordination. In the former complex, the Co-O(water) bond length in the axial direction is 2.167 (2) A, which is longer than the Co-O(carboxylate) and Co-N bond lengths in the equatorial plane [2.055 (2) and 2.096 (2) A, respectively]. In the latter complex, the corresponding bond lengths for Ni-O(water), Ni-O(carboxylate) and Ni-N are 2.127 (2), 2.036 (2) and 2.039 (3) A, respectively. Both crystals are stabilized by similar stacking interactions of the ligand, and also by hydrogen bonds between the hydrate and coordinated water molecules.