One-Pot Self-Assembly of Dinuclear, Tetranuclear, and H-Bonding-Directed Polynuclear Cobalt(II), Cobalt(III), and Mixed-Valence Co(II)/Co(III) Complexes of Schiff Base Ligands with Incomplete Double Cubane Core

The reaction of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and tris(hydroxymethyl)aminomethane (THMAM) was investigated in the presence of Cobalt(II) salts, (X = ClO4−, CH3CO2−, Cl−, NO3−), sodium azide (NaN3), and triethylamine (TEA). In one pot, the variation in Cobalt(II) salt results in the self-assembly of dinuclear, tetranuclear, and H-bonding-directed polynuclear coordination complexes of Cobalt(III), Cobalt(II), and mixed-valence CoIICoIII: [Co2III(H2L−1)2(AP−1)(N3)](ClO4)2 (1), [Co4(H2L−1)2(µ3-1,1,1-N3)2(µ-1,1-N3)2Cl2(CH3OH)2]·4CH3OH (2), [Co2IICo2III(HL−2)2(µ-CH3CO2)2(µ3-OH)2](NO3)2·2CH3CH2OH (3), and [Co2IICo2III (H2L12−)2(THMAM−1)2](NO3)4 (4). In 1, two cobalt(III) ions are connected via three single atom bridges; two from deprotonated ethanolic oxygen atoms in the side arms of the ligands and one from the1-amino-2-propanol moiety forming a dinuclear unit with a very short (2.5430(11) Å) Co-Co intermetallic separation with a coordination number of 7, a rare feature for cobalt(III). In 2, two cobalt(II) ions in a dinuclear unit are bridged through phenoxide O and μ3-1,1,1-N3 azido bridges, and the two dinuclear units are interconnected by two μ-1,1-N3 and two μ3-1,1,1-N3 azido bridges generating tetranuclear cationic [Co4(H2L−1)2(µ3-1,1,1-N3)2(µ-1,1-N3)2Cl2(CH3OH)2]2+ units with an incomplete double cubane core, which grow into polynuclear 1D-single chains along the a-axis through H-bonding. In 3, HL2− holds mixed-valent Co(II)/Co(III) ions in a dinuclear unit bridged via phenoxide O, μ-1,3-CH3CO2−, and μ3-OH− bridges, and the dinuclear units are interconnected through two deprotonated ethanolic O in the side arms of the ligands and two μ3-OH− bridges generating cationic tetranuclear [Co2IICo2III(HL−2)2(µ-CH3CO2)2(µ3-OH)2]2+ units with an incomplete double cubane core. In 4, H2L1−2 holds mixed-valent Co(II)/Co(III) ions in dinuclear units which dimerize through two ethanolic O (μ-RO−) in the side arms of the ligands and two ethanolic O (μ3-RO−) of THMAM bridges producing centrosymmetric cationic tetranuclear [Co2IICo2III (H2L1−2)2(THMAM−1)2]4+ units which grow into 2D-sheets along the bc-axis through a network of H-bonding. Bulk magnetization measurements on 2 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Co(II) ions.

Diaquabis{μ-1,5-bis[(pyridin-2-yl)methylidene]carbonohydrazide(1–)}di-μ-chlorido-tetrachloridotetrazinc(II)

A tetranuclear ZnII complex, [Zn4(C13H11N6O)2Cl6(H2O)2] or {[Zn2(HL)(H2O)(Cl2)](μCl)2[Zn2(HL)(H2O)(Cl)]}2, was synthesized by mixing an equimolar amount of a methanol solution containing ZnCl2 and a methanol solution containing the ligand H2 L [1,5-bis(pyridin-2-ylmethylene)carbonohydrazide]. In the tetranuclear complex, each of the two ligand molecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one ZnII cation is pentacoordinated in a N2OCl2 in a distorted square-pyramidal geometry, while the other ZnII cation is hexacoordinated in a N3OCl2 environment with a distorted octahedral geometry. The basal plane around the pentacoordinated ZnII cation is formed by one chloride anion, one oxygen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical position occupied by a chloride anion. The basal plane of the hexacoordinated ZnII cation is formed by one chloride anion, one hydrazinyl nitrogen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetranuclear complex. A series of intramolecular C—H...Cl hydrogen bonds is observed in each tetranuclear unit. In the crystal, the tetranuclear units are connected by intermolecular C—H...Cl, C—H...O and N—H...O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.

A new co-crystal dinuclear/trinuclear ZnII–ZnII/ZnII–SmIII–ZnII complex with a salen-type Schiff base ligand

In the pentanuclear title complex, [SmZn2(C22H18N2O4)2(NCS)2(C3H7NO)2][Zn2(C22H18N2O4)(NCS)3]·C3H7NO·0.32H2O, namely bis{μ2-6,6′-dimethoxy-2,2′-[phenylene-1,2-diylbis(nitrilomethanylylidene)]diphenolato}-1κ4 O,N,N′,O′:2κ3 O,O′,O 6;2κ3 O,O′,O 6:3κ4 O,N,N′,O′-bis(dimethylformamide-2κO)dithiocyanato-1κN,3κN-2-samarium(III)-1,3-dizinc(II) {μ2-6,6′-dimethoxy-2,2′-[phenylene-1,2-diylbis(nitrilomethanylylidene)]diphenolato-1κ4 O,N,N′,O′:2κ2 O,O′}trithiocyanato-1κN;2κ2 N,N-dizinc(II) dimethylformamide monosolvate 1.32-hydrate, a dinuclear unit and a trinuclear unit co-exist. One of the ZnII centers in the dinuclear unit as well as the two ZnII centers in the trinuclear unit are located in the inner N2O2 cavity of the ligand and are coordinated to the nitrogen atom of one thiocyanate moiety, giving rise to a square-pyramidal geometry. The second ZnII center in the dinuclear unit is coordinated to the two phenolate oxygen atoms of the ligand and to two thiocyanate groups via the nitrogen atom in a tetrahedral geometry. The SmIII ion is eight-coordinated by four phenolate O atoms from the two ligand molecules, two methoxy O atoms from the two ligand molecules and two O atoms from the DFM solvent molecule. In the dinuclear unit, the two methoxy oxygen atoms remain uncoordinated while in the trinuclear unit, for each ligand one methoxy oxygen is coordinated and the other one remains uncoordinated. In the crystal, the trinuclear cationic units and dinuclear anionic units are assembled into infinite layers. These layers are held together via electrostatic interactions, forming a three-dimensional structure. In the dinuclear unit, the C and S atoms of one of the thiocyanate groups are disordered over two sets of sites in a 0.680 (4)(4):0.320 (4) ratio.

Crystal structure of poly[diaqua(μ-2-carboxyacetato-κ3O,O′:O′′)(2-carboxyacetato-κO)di-μ-chlorido-dicobalt(II)]

The asymmetric unit of the title polymer, [Co2(C3H3O4)2Cl2(H2O)2]n, comprises one CoIIatom, one water molecule, one singly deprotonated malonic acid molecule (HMal−; systematic name 2-carboxyacetate) and one Cl−anion. The CoIIatom is octahedrally coordinated by the O atom of a water molecule, by one terminally bound carboxylate O atom of an HMal−anion and by two O atoms of a chelating HMal−anion, as well as by two Cl−anions. The Cl−anions bridge two CoIIatoms, forming a centrosymmetric Co2Cl2core. Each malonate ligand is involved in the formation of six-membered chelate rings involving one CoIIatom of the dinuclear unit and at the same time is coordinating to another CoIIatom of a neighbouring dinuclear unit in a bridging mode. The combination of chelating and bridging coordination modes leads to the formation of a two-dimensional coordination polymer extending parallel to (001). Within a layer, O—Hwater...Cl and O—Hwater...O hydrogen bonds are present. Adjacent layers are linked through O—H...O=C hydrogen bonds involving the carboxylic acid OH and carbonyl groups.

Poly[bis(μ-2-amino-4-nitrobenzoato)di-μ-aqua-dirubidium]

In the structure of the title salt, [Rb2(C7H5N2O4)2(H2O)2]n, the asymmetric unit comprises two independent and different seven-coordinate Rb+cations, one forming an RbO7polyhedron, the other a RbO6N polyhedron, each of which is considerably distorted. The RbO7polyhedron comprises bridging O-atom donors from two water molecules, three carboxylate groups, and two nitro groups. The RbO6N polyhedron comprises the two bridging water molecules, one monodentate amine N-atom donor, one carboxyl O-atom donor and three O-atom donors from nitro groups (one from the chelate bridge). The extension of the dinuclear unit gives a three-dimensional polymeric structure which is stabilized by both intra- and intermolecular amine N—H...O and water O—H...O hydrogen bonds to carboxyl and water O-atom acceptors, as well as a number of inter-ring π–π interactions [minimum centroid–centroid separation = 3.364 (2) Å]. The title salt is isostructural with the analogous caesium salt.

Poly[[μ-chlorido-μ-[2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)propan-2-ol-κ2N4:N4′]-zinc] chloride dihydrate]

The title compound, {[ZnCl(C13H12F2N6O)2]Cl·2H2O}n, is a two-dimensional coordination polymer. The ZnIIatom is six-coordinated by four N atoms from four 2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)propan-2-ol (HFlu) ligands and by two Cl atoms in a distorted octahedral geometry. Two Cl atoms bridge two ZnIIatoms, forming a centrosymmetric dinuclear unit. The HFlu ligands connect the dinuclear units into a 44net parallel to (001) when the dinuclear unit is considered as a node. O—H...O and O—H...Cl hydrogen bonds link the cationic layer, free chloride anions and lattice water molecules. Intralayer π–π interactions between the triazole rings are observed [centroid–centroid distance = 3.716 (6) Å].

Di-μ-iodido-bis[(dimethyl 2,2′-biquinoline-4,4′-dicarboxylate-κ2 N,N′)copper(I)]

In the centrosymmetric dinuclear title complex, [Cu2I2(C22H16N2O4)2], the CuI atom is coordinated in a distorted tetrahedral geometry by an N,N′-bidentate dimethyl 2,2′-biquinoline-4,4′-dicarboxylate ligand and two symmetry-related I atoms, which act as bridges to a symmetry-related CuI atom. The distance between the CuI atoms within the dinuclear unit is 2.6723 (11) Å.

Bis[μ-2-(2-carboxylatophenyl)acetato]-κ3O1,O1′:O2;κ3O2:O1,O1′-bis[aqua(1,10-phenanthroline-κ2N,N′)nickel(II)]

The title compound, [Ni2(C9H6O4)2(C12H8N2)2(H2O)2], is isostructural with the ZnIIanalogue. Each NiIIatom is coordinated in a distorted octahedral geometry by three O atoms from two homophthalate anions, one aqua O atom and two 1,10-phenanthroline N atoms. The two NiIIatoms are linked by two bridging homophthalate dianions into a centrosymmetric dinuclear unit. The dinuclear units are linked into one-dimensional ladder-like chains along [100] by O—H...O hydrogen bonds between the coordinated water molecules and one of the O atoms of the carboxylatomethyl group.