Studies on two cadmium(II) and two zinc(II) complexes of 4′-chloro-2,2′ : 6′,2″-terpyridine with 1 : 1 or 1 : 2 ratio of metal and ligand

The reaction between 4′-chloro-2,2′ : 6′,2″-terpyridine (tpyCl) with d¹⁰ transition-metal ions produced two cadmium(II) and two zinc(II) metal complexes, formulated as [Cd(tpyCl-κ ³ N,N′,N″)(NO₃-κ ² O,O′)(NO₃-κO)(H₂O-κO)] (1), [Cd(tpyCl-κ ³ N,N′,N″)₂](ClO₄)₂ (2), [Zn(tpyCl-κ ³ N,N′,N″)₂](ClO₄)₂ (3), and [Zn(tpyCl-κ ³ N,N′,N″)₂](BF₄)₂ (4). Supramolecular interactions include coordinative bonding, O–H ··· O, O–H ··· Cl, C–H ··· F, and C–H ··· Cl hydrogen bonding and π–π stacking, all of which play essential roles in forming different frameworks of 1–4.     

Melamine-mediated self-assembly of a Cu(II)–methylmalonate complex assisted by π+–π+ and anti-electrostatic H-bonding interactions

A Cu(II)-methylmalonate complex, (C₃H₇N₆)₄[Cu(II)(C₄H₄O₄)₂](H₂O)₄Cl₂ (1) (where C₃H₇N₆ = protonated melamine, C₄H₄O₄ = methylmalonic acid), has been synthesized from aqueous media and its crystal structure was determined by single-crystal X-ray diffraction. The anionic Cu(II)-methylmalonate complex mediated formation of interesting supramolecular assemblies in the solid state by means of ionic interactions with protonated melamine. Moreover, other forces such as antielectrostatic H-bonding and π⁺–π⁺ interactions also play a crucial role in defining the final 3-D architecture of 1. An interesting stacking among protonated melamine molecules is studied by DFT calculations. Lattice water molecules and chlorides form various hydrogen bonds to take part in the self-assembly processes.     

Bimetallic bis(diphenylphosphino)acetylene bridged copper(I) complexes with 1,10-phenanthroline derivatives: synthesis,crystal structure,and spectroscopic characterization

A new series of bimetallic bis(diphenylphosphino)acetylene-bridged copper(I) 1,10-phenanthroline complexes, [Cu₂(dppa)₂(L)₂](BF₄)₂; L?=?1,10-phenanthroline (1); 4-methyl-1,10-phenanthroline (2); 4,7-dimethyl-1,10-phenanthroline (3); and 2,9-dimethyl-1,10-phenanthroline (4), have been prepared and characterized by spectroscopic methods. The X-ray structures of 1 and 4 were determined. The structures consist of centrosymmetric bimetallic 10-membered chair-like dimetallacycles. In 1, intermolecular C–H?π interactions result in bending of the phenanthroline ligand and sterically induced lengthening of one Cu–P bond. In 1–4, the ³¹P NMR downfield coordination shift, relative to the free ligand, correlates with the basic strength of the 1,10-phenanthroline ligands.     

Tris(1,10‐phenanthroline‐κ2N,N′)iron(II) bis(2,4,5‐tricarboxybenzoate) monohydrate and tris(2,2′‐bipyridine‐κ2N,N′)iron(II) 2,5‐dicarboxybenzene‐1,4‐dicarboxylate–benzene‐1,2,4,5‐tetracarboxylic acid–water (1/1/2)

The title compounds, tris(1,10‐phenanthroline‐κ²N,N′)iron(II) bis(2,4,5‐tricarboxybenzoate) monohydrate, [Fe(C₁₂H₈N₂)₃](C₁₀H₅O₈)₂·H₂O, (I), and tris(2,2′‐bipyridine‐κ²N,N′)iron(II) 2,5‐dicarboxybenzene‐1,4‐dicarboxylate–benzene‐1,2,4,5‐tetracarboxylic acid–water (1/1/2), [Fe(C₁₀H₈N₂)₃](C₁₀H₄O₈)·C₁₀H₆O₈·2H₂O, (II), were obtained during an attempt to synthesize a mixed‐ligand complex of Fe^II with an N‐containing ligand and benzene‐1,2,4,5‐tetracarboxylic acid via a solvothermal reaction. In both mononuclear complexes, each Fe^II metal ion is six‐coordinated in a distorted octahedral manner by six N atoms from three chelating 1,10‐phenanthroline or 2,2′‐bipyridine ligands. In compound (I), the Fe^II atom lies on a twofold axis in the space group C2/c, whereas (II) crystallizes in the space group P2₁/n. In both compounds, the uncoordinated carboxylate anions and water molecules are linked by typical O—H...O hydrogen bonds, generating extensive three‐dimensional hydrogen‐bond networks which surround the cations.     

Cobalt(II) and cobalt(III) complexes with 4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine

4′‐Cyanophenyl‐2,2′:6′,2′′‐terpyridine (cptpy) was employed as an N,N′,N′′‐tridentate ligand to synthesize the compounds bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(II) bis(tetrafluoridoborate) nitromethane solvate, [Co^II(C₂₂H₁₄N₄)₂](BF₄)₂·CH₃NO₂, (I), and bis[4′‐(4‐cyanophenyl)‐2,2′:6′,2′′‐terpyridine]cobalt(III) tris(tetrafluoridoborate) nitromethane sesquisolvate, [Co^III(C₂₂H₁₄N₄)₂](BF₄)₃·1.5CH₃NO₂, (II). In both complexes, the cobalt ions occupy a distorted octahedral geometry with two cptpy ligands in a meridional configuration. A greater distortion from octahedral geometry is observed in (I), which indicates a different steric consequence of the constrained ligand bite on the Co^II and Co^III ions. The crystal structure of (I) features an interlocked sheet motif, which differs from the one‐dimensional chain packing style present in (II). The lower dimensionality in (II) can be explained by the disturbance caused by the larger number of anions and solvent molecules involved in the crystal structure of (II). All atoms in (I) are on general positions, and the F atoms of one BF₄⁻ anion are disordered. In (II), one B atom is on an inversion center, necessitating disorder of the four attached F atoms, another B atom is on a twofold axis with ordered F atoms, and the C and N atoms of one nitromethane solvent molecule are on a twofold axis, causing disorder of the methyl H atoms. This relatively uncommon study of analogous Co^II and Co^III complexes provides a better understanding of the effects of different oxidation states on coordination geometry and crystal packing.     

Cobalt(II) complexes of the 2-aminopicolineN-oxides and 2-amino-4, 6-lutidineN-oxide

Summary Cobalt(II) complexes of the four 2-aminopicolineN-oxides and 2-amino-4, 6-lutidineN-oxide were prepared from Co(BF₄)₂ and CoCl₂, and characterized by partial elemental analyses, magnetic moments, molar conductivities, thermal analyses, and by plasma desorption mass, i.r., electronic, and e.s.r. spectroscopy. The compounds derived from CoCl₂ are 4-coordinate, tetrahedral, molecular solids with CoO₂Cl₂ chromophores. Dq values range from 332 to 382 cm^–1 and those of B from 758 to 813 cm^–1 for the five solids. Three of the compounds prepared from Co(BF₄)₂ are octahedral with the following stoichiometry: [CoL₆](BF₄)₂ where L=2-amino-4-picolineN-oxide and [CoL₅(H₂O)] (BF₄)₂ where L is either 2-amino-3-or 2-amino-5-picolineN-oxide. Both 2-amino-6-picolineN-oxide and 2-amino-4, 6-lutidineN-oxide gave square planar [CoL ₄ ²⁺ ] complex ions. While numerous square planar cobalt(II) centers are known, those described here are probably the first examples with monodentate ligands and a CoO₄ center. They have weak e.s.r. spectra, magnetic moments between 2 and 3 BM and characteristic d-d spectra.     

[Cu(phen)2(μ‐IDA)Cu(phen)](ClO4)2·CH3OH: tridentate and monodentate binding to two copper(II) species by a bridging ligand

The stoichiometric reaction of 1,10‐phenanthroline (phen), imino­di­acetic acid (IDA‐H₂) and Cu(ClO₄)₂ in a H₂O–CH₃OH (2:1) solution yields μ‐imino­diacetato‐2:1κ⁴O,N,O′:O′′‐tris(1,10‐phenanthroline)‐1κ⁴N,N′;2κ²N,N′‐dicopper(II) diperchlorate methanol solvate, [Cu₂(C₄H₅NO₄)(C₁₂H₈N₂)₃](ClO₄)₂·CH₃OH. The IDA ligand bridges the two Cu^II ions via a carboxyl­ate group and uses one further N and an O atom of the second carboxylate group to complete a fac‐tridentate coordination at one Cu centre. A phen ligand completes a distorted square‐pyramidal coordination at this metal atom, although there is weak coordination by a perchlorate O atom at a sixth position. The second Cu centre has a distorted trigonal–bipyramidal coordination to two phen moieties and a carboxyl­ate O atom.     

Synthesis and structures of pyridoannelated 1,2,3,4-tetrazine 1,3-dioxides

Treatment of 2- and 4-amino-3-(tert-butyl-NNO-azoxy)pyridines with nitrating agents (N₂O₅or NO₂BF₄) afforded the first representatives of pyridoannelated 1,2,3,4-tetrazine di-N-oxides, viz., pyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (9), 7-nitropyrido[2,3-e][1,2,3,4]tetrazine 1,3-dioxide (10), and pyrido[3,4-e][1,2,3,4]tetrazine 2,4-dioxide (11). These compounds were studied by ¹H, ¹³C, and ¹⁴N NMR spectroscopy. The 1:1 complex of compound 10 with benzene was studied by X-ray diffraction analysis.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2471–2477, November, 2004.     

Two nickel complexes stabilized by nitrate counter‐ions

Two new nickel nitrates, di­aqua­bis(3,4,7,8‐tetra­methyl‐1,10‐phenanthroline‐κ²N,N′)­nickel(II) dinitrate methanol solvate, [Ni(C₁₆H₁₆N₂)₂(H₂O)₂](NO₃)₂·CH₄O, (I), and tri­aqua­[2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine‐κ³N¹,N²,N⁶]nickel(II) di­ni­trate trihydrate, [Ni(C₁₈H₁₂N₆)(H₂O)₃](NO₃)₂·3H₂O, (II), are reported. In both structures, the cation is octahedrally coordinated, to two bidentate 3,4,7,8‐tetra­methyl‐1,10‐phenanthroline (tmp) and two water mol­ecules in (I), and to one tridentate 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tpt) and three water mol­ecules in (II). Both structures are stabilized by extensive hydrogen‐bonding interactions.     

Two cobalt(III) mono‐dimethylglyoximates isolated from one reaction

The reaction of cobalt(II) nitrate hexahydrate with dimethylglyoxime (DMGH₂) and 1,10‐phenanthroline (phen) in a 1:1:2 molar ratio results in two Co^III mono‐dimethylglyoximates having two chelating phen ligands in cis positions and the Co^III atom coordinated by six N atoms in a distorted octahedral coordination geometry. The isolated products differ in the deprotonation state of the DMGH₂ ligand. In [μ‐hydrogen bis(N,N′‐dioxidobutane‐2,3‐diimine)]tetrakis(1,10‐phenanthroline)cobalt(III) trinitrate ethanol disolvate 1.87‐hydrate, [Co₂(C₄H₆N₂O₂)(C₄H₇N₂O₂)(C₁₂H₈N₂)₄](NO₃)₃·2C₂H₆O·1.87H₂O, (I), the C₂‐symmetric cation is formed with the coordination [Co(DMG)(phen)₂]⁺ cations aggregating via a very strong O⁻...H⁺...O⁻ hydrogen bond with an O...O distance of 2.409 (4) Å. Crystals of (I) exhibit extensive disorder of the solvent molecules, the nitrate anions and one of the phen ligands. Compound (I) is a kinetic product, not isolated previously from similar systems, that transforms slowly into (N‐hydroxy‐N′‐oxidobutane‐2,3‐diimine)bis(1,10‐phenanthroline)cobalt(III) dinitrate ethanol monosolvate 0.4‐hydrate, [Co(C₄H₇N₂O₂)(C₁₂H₈N₂)₂](NO₃)₂·C₂H₆O·0.40H₂O, (II), with the DMGH⁻ ligand hydrogen bonded to one of the nitrate anions. In (II), the solvent molecules and one of the nitrate anions are disordered.     

Synthesis and characterization of some novel cadmium(II) complexes with 3-hydroxypicolinic acid (3-OHpicH): Crystal and molecular structures of [CdI(3-OHpic)(3-OHpicH)(H2O)]2, [Cd(3-OHpic)2(H2O)2] and [Cd(3-OHpic)2]n

Cadmium(II) complexes of 3-hydroxypicolinic acid, namely [CdI(3-OHpic)(3-OHpicH)(H₂O)]₂ (1), [Cd(3-OHpic)₂(H₂O)₂] (2) and [Cd(3-OHpic)₂]_n (3) were prepared and characterized by spectroscopic methods (IR, NMR) and their molecular and crystal structures were determined by X-ray crystal structure analysis. Complexes 1 and 2 were prepared in similar reaction conditions using different cadmium(II) salts: cadmium(II) iodide and cadmium(II) acetate dihydrate, respectively, while 3 was prepared by recrystallization of 2 from N,N-dimethylformamide solution. Various coordination modes of 3-OHpicH in 1–3 were established in the solid state: bidentate N,O-chelated mode in 1 and 2, monodentate mode through the carboxylate O atom from zwitterionic ligand in 1 and bidentate N,O-chelated and bridging mode in 3. In the DMF solution of all prepared complexes, only monodentate mode of 3-OHpicH binding to cadmium(II) through the carboxylate O atom was established by ¹H, ¹³C, ¹⁵N and ¹¹³Cd NMR spectroscopy.     

Structural diversity in pseudohalide complexes of cadmium(II) with N-methylthiourea (Metu): Polymeric [Cd(Metu)2(NCS)2]n versus monomeric [Cd(Metu)2(CN)2]

Cadmium(II) complexes, catena-poly[bis(thiocyanato-κN)bis(N-methylthiourea)cadmium(II)], [Cd(Metu)₂(NCS)₂]_n (1) and dicyanidobis(N-methylthiourea)cadmium(II), [Cd(Metu)₂(CN)₂] (2) were prepared and their structures were determined by single crystal X-ray analysis. In 1, the cadmium(II) ion is bound to four sulfur atoms of bridging Metu ligands and two nitrogen atoms of thiocyanate adopting a distorted octahedral environment. In 2, the geometry around cadmium is distorted tetrahedral attained by two cyanide ions and two methylthiourea molecules bound through the sulfur atoms. The crystal structures of both complexes show intra and intermolecular hydrogen bonding interactions. The complexes were also characterized by IR and NMR spectroscopy and the spectroscopic data were discussed in terms of the nature of bonding.     

Predictable Electronic Tuning By Choice of Azine Substituent in Five Iron(II) Triazoles: Redox Properties and DFT Calculations

Five new mononuclear iron(II) tris‐ligand complexes, and four solvatomorphs, have been made from the azine‐substituted 1,2,4‐triazole ligands ( L^azine ): [Fe^II( L^pyridazine )₃](BF₄)₂ ( 1 ), [Fe^II( L^pyrazine )₃](BF₄)₂ ( 2 ), [Fe^II( L^pyridine )₃](BF₄)₂ ( 3 ), [Fe^II( L^2pyrimidine )₃](BF₄)₂ ( 4 ), and [Fe^II( L^4pyrimidine )₃](BF₄)₂ ( 5 ). Single‐crystal XRD and solid‐state magnetometry reveal that all of them are low‐spin (LS) iron(II), except for solvatomorph 5 ?4 H₂O. Evans method NMR studies in CD₂Cl₂, (CD₃)₂CO and CD₃CN show that all are LS in these solvents, except 5 in CD₂Cl₂ (consistent with L^4pyrimidine imposing the weakest field). Cyclic voltammetry in CH₃CN vs. Ag/0.01 m AgNO₃ reveals an, at best quasi‐reversible, Fe^III/II redox process, with E_pa increasing from 0.69 to 0.99 V as the azine changes: pyridine< pyridazine<2‐pyrimidine<4‐pyrimidine< pyrazine. The observed E_pa values correlate linearly with the DFT calculated HOMO energies for the LS complexes.     

Syntheses and structures of two new uranyl complexes [UO2(DPDPU)2(NO3)2](C6H5CH3) and [UO2(PMBP)2(DPDPU)](CH3C6H4CH3)0.5

Two new uranyl complexes [UO₂(DPDPU)₂(NO₃)₂](C₆H₅CH₃) (1) and [UO₂(PMBP)₂ (DPDPU)](CH₃C₆H₄CH₃)_0.5 (2), (DPDPU?=?N,N′-dipropyl-N,N′-diphenylurea, HPMBP?= 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5) were synthesized and characterized. The coordination geometry of the uranyl atom in 1 is distorted hexagonal bipyramidal, coordinated by two oxygen atoms of two DPDPU molecules and four oxygen atoms of two bidentate nitrate groups. The coordination geometry of the uranyl atom in 2 is distorted pentagonal bipyramidal, coordinated by one oxygen atom of one DPDPU molecule and four oxygen atoms of two chelating PMBP molecules.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine. Part 4. The 3-piperidinyl derivative

Summary Metal ion complexes of the thiosemicarbazone, 3-piperidinyl-3-thiocarboxylic acid-2-[1-(2-pyridyl)ethylidene]hydrazide (HLpip) have been prepared and spectrally characterized. HLpip coordinates both as the deprotonated ligand (i.e., pyridylN, azomethineN, and thione sulphur) and the neutral ligand (i.e., pyridylN and azomethineN) with the sulphur possibly weakly coordinating in [Ni(HLpip)₂](BF₄)₂. All three preparative cobalt(II) salts yielded cobalt(III) cationic complexes. The nickel(II) and copper(II) chloride salts gave [M(Lpip)Cl] solids while complexes involving the neutral ligand were prepared with the corresponding bromide salts. Significant differences in the spectral properties of the various complexes are observed when compared to other thiosemicarbazones prepared from 2-acetylpyridine.     

Synthesis and selected reactions of pentakis ( t -octylisocyanide)cobalt(II) complexes

The ligand 1,1,3,3-tetramethylbutylisocyanide, CNCMe₂CH₂CMe₃, i.e. t-octylisocyanide, with Co(ClO₄)₂ · 6H₂O or Co(BF₄)₂ · 6H₂O in ethanol, produces pentakis(alkylisocyanide)cobalt(II) complexes, [Co(CNC₈H₁₇-t)₅](ClO₄)₂ (1) and [Co(CNC₈H₁₇-t)₅](BF₄)₂ · 2.0H₂O (2). These Co(II) complexes undergo reduction/substitution upon reaction with trialkylphosphine ligands to produce [Co(CNC₈H₁₇-t)₃{P(C₄H₉-n)₃}₂]ClO₄ (3), [Co(CNC₈H₁₇-t)₃{P(C₄H₉-n)₃}₂]BF₄ (4), and [Co(CNC₈H₁₇-t)₃{P(C₃H₇-n)₃}₂]ClO₄ (5). Complex 3 is oxidized with AgClO₄ to produce [Co(CNC₈H₁₇-t)₃{P(C₄H₉-n)₃}₂](ClO₄)₂ (6). Complex 1 yields [Co(CNC₈H₁₇-t)₄py₂](ClO₄)₂ (7) upon dissolving in pyridine. Reactions with triarylphosphine and triphenylarsine ligands were unsatisfactory. The chemistry of 1 and 2 is therefore more similar to that of Co(II) complexes with CNCMe₃ than with CNCHMe₂, other alkylisocyanides, or arylisocyanides, but shows some behavior dissimilar to any known Co(II) complexes of alkylisocyanides or arylisocyanides. Infrared and electronic spectra, magnetic susceptibility, molar conductivities, and cyclic voltammetry are reported and compared with known complexes. ¹H, ¹³C, and ³¹P NMR data were also measured for the diamagnetic complexes 3, 4, and 5.     

Chloro­(hist­amine)(1,10‐phenanthro­line)copper(II) chloride monohydrate

In the cationic complex present in the title compound, chloro­[2‐(4‐imidazolyl‐κN¹)­ethyl­amine‐κN](1,10‐phenanthroline‐κ²N,N′)copper(II) chloride monohydrate, [CuCl(C₅H₉­N₃)­(C₁₂H₈N₂)]Cl·H₂O, the metal centre adopts a five‐coordinate geometry, ligated by the two phenanthroline N atoms, two amine N atoms of the hist­amine ligand (one aliphatic and one from the imidazole ring) and a chloro ligand. The geometry around the Cu atom is a distorted compressed trigonal bipyramid, with one phenanthroline N and one imidazole N atom in the axial positions, and the other phenanthroline N atom, the histamine amine N atom and the chloro ligand in the equatorial positions. The structure includes an uncoordinated water mol­ecule, and a Cl⁻ ion to complete the charge. The water mol­ecule is hydrogen bonded to both Cl⁻ ions (coordinated and uncoordinated), and exhibits a close Cu⋯H contact in the equatorial plane of the bipyramid.     

Two novel bis­(2,9‐dimeth­yl‐1,10‐phenanthroline)copper(I) complexes: [Cu(dmp)2]2(PF6)2·0.5(bpmh)·CH3CN and [Cu(dmp)2][N(CN)2]

Two new salts of the cation [Cu^I(dmp)₂]⁺ (dmp is 2,9‐dimeth­yl‐1,10‐phenanthroline, C₁₄H₁₂N₂), namely bis­[bis­(2,9‐dimeth­yl‐1,10‐phenanthroline‐κ²N,N′)copper(I)] bis­(hexa­fluorophos­phate) hemi[bis­(4‐pyridylmethyl­idene)hydrazine] acetonitrile solvate, [Cu(C₁₄H₁₂N₂)₂]₂(PF₆)₂·0.5C₁₂H₁₀N₄·C₂H₃N or [Cu(dmp)₂]₂(PF₆)₂·0.5(bpmh)·CH₃CN [bpmh is bis­(4‐pyridylmethyl­idene)hydrazine, C₁₂H₁₀N₄], (I), and bis­(2,9‐dimeth­yl‐1,10‐phenanthroline‐κ²N,N′)copper(I) dicyanamide, [Cu(C₁₄H₁₂N₂)₂](C₂N₃) or [Cu(dmp)₂][N(CN)₂], (II), are reported. The Cu—N bond lengths and the distortion from idealized tetra­hedral geometry of the dmp ligands are discussed and compared with related compounds. The bpmh molecule in (I) is π–π stacked with a dmp ligand at a distance of 3.4 Å, rather than coordinated to the metal atom. The molecule lies across an inversion center in the crystal. In (II), the normally coordinated dicyanamide mol­ecule is present as an uncoordinated counter‐ion.     

Tetrahedral complexes of zinc(II) chloride with N- and O-containing organic ligands: Synthesis and crystal structures of [ZnCl2(C12H12N2O)] and [ZnCl2(H2O)2](Me4Pyz)2

New complex chlorides [ZnCl₂(ODA)] (I) (ODA=oxydianiline, C₁₂H₁₂N₂O) and [ZnCl₂(H₂O)₂](Me₄Pyz)₂ (II) (Me₄Pyz = 2,3,5,6-tetramethylpyrazine) were synthesized and crystallographically characterized. Crystals of I are monoclinic, space group C2/c, a = 22.682(2) ?, b = 12.646(1) ?, c = 9.951(1) ?, β = 93.23(2)°, V = 2849.7(5) ?³, ρ_calc = 1.569 g/cm³, Z = 8. Structure I contains cyclic fragments consisting of two tetrahedral complexes (ZnCl₂N₂) and two coordinated bridging oxydianiline ligands. Crystals of II are monoclinic, space group P2(1)/c, a = 8.972(2) ?, b = 13.862(3) ?, c = 17.528(4) ?, β = 101.72(3)°, V = 2134.5(7) ?³, ρ_calc = 1.384 g/cm³, Z = 4. In structure II, supramolecular pseudo-metallocycles are formed due to formation of hydrogen bonds O(w)-H…N between coordinated water molecules and noncoordinated nitrogen atoms of tetramethylpyrazine molecules.