Halogen-Dependent Diversity and Weak Interactions in the Heterometallic Ni/Cd Complex Solids: Structural and Theoretical Investigation.

Three novel heterometallic Ni/Cd coordination compounds [Ni(en)3][CdCl4]∙3dmso (1), [Ni(en)2(dmf)2][CdBr4] (2), and [Ni(en)3]2[CdI4](I)2 (3) have been synthesized through the self-assembly process in a one-pot reaction of cadmium oxide, nickel salt (or nickel powder), NH4X (X = Cl, Br, I), and ethylenediamine in non-aqueous solvents dmso (for 1) or dmf (for 2 and 3). Formation of the one- (1) or three-dimensional (2 and 3) hydrogen-bonded frameworks has been observed depending on the nature of the [CdX4]2- counter-anion, as well as on the nature of the solvent. The electronic structures of [Ni(en)3]2+ and [Ni(en)2(dmf)2]2+ cations were studied at the DFT and CASSCF levels, including the ab initio ligand field theory (AILFT) calculations. The non-covalent intermolecular contacts between the cationic nickel and anionic cadmium blocks in the solid state were investigated by the QTAIM analysis. The mechanism of ligand substitution at the nickel center in [Ni(en)2(dmf)2]2+ was theoretically investigated at the ωB97X-D4/ma-def2-TZVP//DLPNO-CCSD(T)/ma-def2-TZVPP level. The results demonstrate that thermodynamic factors are structure-determining ones due to low energy barriers of the rotation of dmf ligands in [Ni(en)2(dmf)2]2+ (below 3 kcal mol-1) and the reversible transformation of [Ni(en)2(dmf)2]2+ into [Ni(en)3]2+ (below 20 kcal mol-1).

Supramolecular Diversity, Theoretical Investigation and Antibacterial Activity of Cu, Co and Cd Complexes Based on the Tridentate N,N,O-Schiff Base Ligand Formed In Situ.

The four new complexes, [Cu(HL1)(L2)Cl] (1), [Cu(HL1)(L1)]∙Cl∙2H2O (2), [Co(L1)2]∙Cl (3) and [Cd(HL1)I2]∙dmso (4), have been prepared by one-pot reactions of the respective chloride or iodide metal salt with a non-aqueous solution of the polydentate Schiff base, HL1, resulted from in situ condensation of benzhydrazide and 2-pyridinecarboxaldehyde, while a ligand HL2, in case of 1, has been formed due to the oxidation of 2-pyridinecarboxaldehyde under reaction conditions. The crystallographic analysis revealed that the molecular building units in 1-4 are linked together into complex structures by hydrogen bonding, resulting in 1D, 2D and 3D supramolecular architectures for 1, 2 and 4, respectively, and the supramolecular trimer for 3. The electronic structures of 1-4 were investigated by the DFT theoretical calculations. The non-covalent interactions in the crystal structures of 1-4 were studied by means of the Hirshfeld surface analysis and the QTAIM theory with a special focus on the C-H⋯Cl bonding. From the DFT/DLPNO-CCSD(T) calculations, using a series of charged model {R3C-H}0⋯Cl- assemblies, we propose linear regressions for assessment of the interaction enthalpy (ΔH, kcal mol-1) and the binding energy (BE, kcal mol-1) between {R3C-H}0 and Cl- sites starting from the electron density at the bond critical point (ρ(rBCP), a.u.): ΔH = -678 × ρ(r) + 3 and BE = -726 × ρ(r) + 4. It was also has been found that compounds 1, 3 and 4 during in vitro screening showed an antibacterial activity toward the nine bacteria species, comprising both Gram-positive and Gram-negative, with MIC values ranging from 156.2 to 625 mg/L. The best results have been obtained against Acinetobacter baumannii MßL.

Crystal structure of {2-[({2-[(2-amino-eth-yl)amino]-eth-yl}imino)-meth-yl]pheno-lato}aqua-copper(II) bromide.

In the mononuclear copper(II) title complex, [Cu(C11H16N3O)(H2O)]Br, the Cu(II) atom is coordinated by one O and three N atoms of the Schiff base ligand that forms together with one water mol-ecule a slightly distorted [CuN3O2] square-pyramidal polyhedron. The deviation of the Cu(II) atom from the mean equatorial plane is 0.182 (2) Å. The equatorial plane is nearly coplanar to the aromatic ring of the ligand [angle between planes = 10.4 (1)°], and the water molecule is situated in the apical site. All coordinating atoms (except the imine nitro-gen) and the bromide ion contribute to the formation of the N-H⋯Br, O-H⋯Br and O-H⋯O hydrogen bonds, which link mol-ecules into chains along [01-1].

catena-Poly[[manganese(III)-bis-{µ-2-[(2-hy-droxy-eth-yl)imino-meth-yl]-6-meth-oxy-phenolato-κ(3) O (1),N:O (2);κ(3) O (2):N,O (1)}] iodide].

In the title one-dimensional coordination polymer, {[Mn(C10H12NO3)2]I} n , the potentially tetra-dentate (O,O,O,N) 2-[(2-hy-droxy-eth-yl)imino-meth-yl]-6-meth-oxy-phenol (H2 L) ligands are mono-deprotonated (as HL (-)) and coordinated by the metal ions in a tridentate chelate-bridging fashion [2.0111112]. The Mn(III) atom possesses a distorted trans-MnO4N2 octa-hedral coordination environment. The bridging ligands lead to [010]-chain polymeric cations {[Mn(HL)2](+)} n in the crystal. The charge-balancing iodide ions are disordered over two sites in a 0.690 (2):0.310 (2) ratio and a weak O-H⋯I hydrogen bond occurs. The crystal studied was found to be a racemic twin.

Tris(2,2'-bipyridine-κN,N')cobalt(III) tris-(oxalato-κO,O)ferrate(III) mono-hydrate.

The title compound, [Co(C(10)H(8)N(2))(3)][Fe(C(2)O(4))(3)]·H(2)O, con-sists of two discrete tris-(chelate) metal ions (Co(III)N(6) and Fe(III)O(6) chromophores) and a water mol-ecule. The structure is highly symmetrical; the Co(III) and Fe(III) ions occupy positions with site symmetry 3.2. The coordination polyhedra of the metal atoms have a nearly octa-hedral geometry with noticeable trigonal distortions. The Co-N and Fe-O bond lengths are equal by symmetry, viz. 1.981 (2) and 1.998 (4) Å, respectively. The cations and anions are arranged alternately along their threefold rotation axes parallel to [001], forming chains that are packed in a hexa-gonal manner. The water mol-ecules occupy voids between the chains. The crystal under investigation was an inversion twin.

Bis(2-hy-droxy-imino-methyl-6-meth-oxy-phenolato-κ(2)N,O(1))copper(II).

In the title compound, [Cu(C(8)H(8)NO(3))(2)], the nearly planar mol-ecule (r.m.s. deviation = 0.037 Å) is centrosymmetric with the Cu(II) atom lying on an inversion center. The Cu(II) atom is tetra-coordinated, displaying a slightly distorted square-planar geometry. The main deviation from the ideal geometry is seen in the differences in the Cu-O [1.8833 (10) Å] and Cu-N [1.9405 (13) Å] bond lengths, while angular deviations are less than 3°. Intra-molecular O-H⋯O and inter-molecular Csp(2)-H⋯O hydrogen bonds form S(5) and R(2) (2)(8) ring motifs, respectively. The latter inter-action results in chains of mol-ecules along [100].

Hexa-kis-(dimethyl-formamide-κO)manganese(II) µ-oxido-bis-[trichlorido-ferrate(III)].

The title compound, [Mn(C(3)H(7)NO)(6)][Fe(2)Cl(6)O], was obtained unintentionally as a product of an attempted synthesis of heterometallic complexes with Schiff base ligands using manganese powder and FeCl(3)·6H(2)O as starting materials. In the [Fe(2)OCl(6)](2-) anion, the O atom and the Fe atom occupy positions with site symmetry [Formula: see text] and 3, respectively, resulting in a linear Fe-O-Fe angle and a staggered conformation. The octa-hedrally surrounded cation (site symmetry [Formula: see text]) and the [Fe(2)Cl(6)O](2-) anion are alternately stacked along [001].

Crystal structure of imidazo[1,5-a]pyridinium-based hybrid salt (C13H12N3)2[MnCl4].

A new organic-inorganic hybrid salt [L]2[MnCl4] (I) where L + is the 2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridinium cation, is built of discrete organic cations and tetra-chlorido-manganate(II) anions. The L + cation was formed in situ in the oxidative cyclo-condensation of 2-pyridine-carbaldehyde and CH3NH2·HCl in methanol. The structure was refined as a two-component twin using PLATON (Spek, 2020 ▸) to de-twin the data. The twin law (-1 0 0 0 - 1 0 0.5 0 1) was applied in the refinement where the twin component fraction refined to 0.155 (1). The compound crystallizes in the space group P21/c with two crystallographically non-equivalent cations in the asymmetric unit, which possess similar structural conformations. The fused pyridinium and imidazolium rings of the cations are virtually coplanar [dihedral angles are 0.89 (18) and 0.78 (17)°]; the pendant pyridyl rings are twisted by 36.83 (14) and 36.14 (13)° with respect to the planes of the remaining atoms of the cations. The tetra-hedral MnCl4 2- anion is slightly distorted with the Mn-Cl distances falling in the range 2.3469 (10)-2.3941 (9) Å. The distortion value of 0.044 relative to the ideal tetra-hedron was obtained by continuous shape measurement (CShM) analysis. In the crystal, the cations and anions form separate stacks propagating along the a-axis direction. The organic cations display weak π-π stacking. The anions, which are stacked identically one above the other, demonstrate loose packing; the minimum Mn⋯Mn separation in the cation stack is approximately 7.49 Å. The investigation of the fluorescent properties of a powdered sample of (I) showed no emission. X-band EPR data for (I) at 293 and 77 K revealed broad fine structure signals, indicating moderate zero-field splitting.

Versatile coordination behaviour of the chloro-tetrazine-picolylamine ligand: mixed-valence binuclear Cu(i)/Cu(ii) complexes.

The 3-Cl-6-amino-(2'-picolyl)-1,2,4,5-tetrazine ligand HL1 has been synthesized and structurally characterized. Its versatile coordination behavior has been evidenced through reactions with Cu(Hfac)2 and Cu(triflate)2 precursors, which provided mixed-valence bimetallic Cu1.5Cu1.5 complexes [Cu2(µ-Cl)(L1)2] 2 and [Cu2(µ-triflate)(L1)2] 5. Changing the Cu(ii) precursor and the solvent leads to the formation of mononuclear octahedral Cu(ii) complexes [CuCl2(HL1)2]·2CH3CN 3 and [Cu(Hfac)2(HL1)] 4, in which only the amino-pyridine unit is involved in the coordination of the metal center. In contrast, in complexes 2 and 5, the ligands are deprotonated and bridge the metal centers as pyridine-amido-tetrazine fragments, while a bridging chloride or triflate ligand completes the coordination sphere of the metal ions. The Cu-Cu distances of 2.4313(4) Å in 2 and 2.5198(10) Å in 5 lie among the shorter values within mixed-valence bimetallic Cu complexes. Mixed-valence character is strongly supported by DFT calculations, showing the equal repartition of the unpaired electron between the two metal centers.

Co-existence of ferro- and antiferromagnetic interactions in a hexanuclear mixed-valence CoMnMn cluster sustained by a multidentate Schiff base ligand.

The successful utilization of the "direct synthesis" approach yielded the unprecedented hexanuclear complex of formula [Co2MnMn(L1)4Cl2(µ3-O)2(dmf)4]·2dmf (1) (H3L is the Schiff base derived from the condensation of salicylaldehyde and 3-aminopropane-1,2-diol). Single crystal X-ray analysis revealed that 1 crystallizes in the monoclinic system P21/c and it contains a rare mixed-valence {CoMnMn(µ2-O)8(µ3-O)2} core where all metal ions are linked through the phenolato and alkoxo groups of the L3- ligand. Besides the charge balance resulting from the X-ray structure, the oxidation state of the metal ions has been confirmed by XPS spectroscopy. Cryomagnetic studies indicate the coexistence of ferro- (MnIV-MnII, J2 = +1.10(3) cm-1, J3 = +2.19(3) cm-1; MnII-MnII, j = +0.283(3) cm-1) and antiferromagnetic interactions (MnIV-MnIV, J1 = -17.31(4) cm-1), with the six-coordinate CoIII ions being diamagnetic. DFT type calculations were carried out to substantiate these values. The energy diagram for the different spin states using the best-fit parameters shows the occurrence of six low-lying spin states (S = 0-5) which are close in energy but clearly separated from the remaining ones, with the ground spin state being S = 5. Complex 1 is found to be the first example where weak ferromagnetic exchange between MnII ions through the long -O-MnIV-O- pathway takes place.

Details make the difference: a family of tetranuclear CuIIMnIII complexes with cube-like and double open cube-like cores.

The "direct synthesis" approach, namely one-pot reaction of metal powders and ammonium salt with a methanol solution of a polydentate Schiff base (H2L) formed in situ from salicylaldehyde and ethanolamine, has been successfully used for the preparation of the new heterometallic compounds [Cu3Mn(L)4(CH3OH)3]I3 (1), [Cu3Mn(L)4(CH3OH)3(H2O)]NCS·H2O (2), [Cu3Mn(L)4(CH3OH)(H2O)2.55]Br·0.45H2O (3) and [Cu3Mn(L)4(H2O)3.4]BF4·0.6H2O (4). Crystallographic analysis revealed that 1-4 are based on the tetranuclear core {CuMnIII(µ3-O)4} where the metal centres are joined by the oxygen bridges of Schiff base ligands forming a cube-like arrangement. The novel heterometallic compound [Cu3Mn(L)4(CH3OH)3]2[Mn(NCS)4]·2CH3OH (5) has been obtained by the "building block" approach using the reaction of [Cu(HL)2] with manganese acetate and NH4NCS in methanol. The crystal structure of 5 revealed the {CuMnIII(µ-O)2(µ3-O)2} metal core which can be viewed as a double open cube. In spite of a similar {Cu3MnO4} atom set in the cores of 1-5, the complexes show rather different molecular structures and significantly differ by the number and combinations of coordinated CH3OH/H2O solvent molecules. Variable-temperature (2-300 K) magnetic susceptibility along with variable-field magnetization measurements of 1-5 showed a decrease of the effective magnetic moment value at low temperature, indicative of the antiferromagnetic coupling of medium size (-55 to -22 cm-1). For these systems resembling a compressed prism the coupling constant in walls J4 correlates with the averaged bonding angles in walls α: J4vs. α develops approximately according to a straight line.

Crystal structure of catena-poly[calcium-di-µ3-benzoato-κ(6) O,O':O-µ2-(dimethyl sulfoxide)-κ(2) O:O].

In the title complex, [Ca(C7H5O2)2(C2H6OS)] n , the Ca(2+) ion (site symmetry m..) is surrounded by eight O atoms, six from two bridging-chelating tridentate benzoate carboxyl groups and two from a bridging dimethyl sulfoxide mol-ecule (point group symmetry m..), giving an irregular coordination geometry [Ca-O bond length range = 2.345 (2)-2.524 (2) Å]. One-dimensional coordination complex chains extending parallel to c are generated in which the triply µ2-O-bridged Ca(2+) cations are separated by 3.6401 (5) Å. In the crystal, weak intra-chain C-H⋯π hydrogen bonds are present between the methyl H atoms of the dimethyl sulfoxide mol-ecules as donors and the aromatic rings as acceptors [C-H⋯Cg = 3.790 (4) Å].

Structural, magnetic, high-frequency and high-field EPR investigation of double-stranded heterometallic [{Ni(en)2}2(micro-NCS)4Cd(NCS)2](n).nCH3CN polymer self-assembled from cadmium oxide, nickel thiocyanate and ethylenediamine.

A novel heterometallic 1D coordination polymer [{Ni(en)2}2(micro-NCS)4Cd(NCS)2](n) x nCH3CN (en = ethylenediamine) has been prepared using the self-assembly process in a one-pot reaction of cadmium oxide, nickel and ammonium thiocyanates with an acetonitrile solution of ethylenediamine. The complex consists of an uncommon cis-Cd(SCN)4(NCS)2(4-) fragment and a rare combination of cis-Ni(en)2(2+) and trans-Ni(en)2(2+) building blocks linked by micro(1,3)-NCS bridges into a double-stranded zigzag chain structure. Each chain is comprised of [Ni2Cd2(micro-NCS-N,S)4)] macrocycles with chair-like and rectangular-like shapes arrayed alternately. The shortest intrachain CdCd separations are 9.535(1) and 10.868(2) A, while the nearest NiNi distances are 5.418(1) and 6.612(2) A. A network of weak N-HS hydrogen bonds, involving the terminal NCS ligands and NH2-groups of en, links the infinite chains and results in the formation of an extended supramolecular three-dimensional framework. Variable-temperature (1.8-300 K) magnetic susceptibilities show a slight change of the micro(B) value at low temperature, indicative of weak antiferromagnetic interactions (J = 1.55 cm-1) between magnetic canters. High-field, high-frequency (100-400 GHz) EPR spectra were simulated using S = 1 ground state for separate Ni2+ ions with the spin Hamiltonian parameters g = 2.165, D = 0.45 cm-1 and E = 0.03 cm(-1). According to DFT calculations, the D and E parameters are -0.35 cm(-1) and 0.049 cm-1 for the cis arrangement of Ni2+ and 0.58 cm(-1) and 0.012 cm(-1) for trans.

A three-dimensional framework of bis[tris(ethylenediamine)zinc] tetraiodocadmate diiodide assisted by N-H...I hydrogen bonds.

The title salt, [Zn(C(2)N(2)H(8))(3)](2)[CdI(4)]I(2), conventionally abbreviated [Zn(en)(3)](2)[CdI(4)]I(2), where en is ethylenediamine, contains discrete [Zn(en)(3)](2+) cations and [CdI(4)](2-) anions with distorted octahedral and nearly tetrahedral geometries, respectively, as well as uncoordinated I(-) ions. The cation and the free I(-) anion lie on twofold rotation axes and the [CdI(4)](2-) anion lies on a -4 axis in the space group I-42d. The structure exhibits numerous weak inter-ionic hydrogen bonds of two types, viz. N-H...I(-)(free ion) and N-H...I([CdI(4)](2-)), which support the resulting three-dimensional framework.