Binuclear Molecules Research Articles

Cobalt(II) Paddle-Wheel Complex with 3,5-Di(tert-butyl)-4-hydroxybenzoate Bridges: DFT and ab initio Calculations, Magnetic Dilution, and Magnetic Properties

A new binuclear "paddle-wheel" complex, [Co2(bhbz)4(EtOH)2]·4EtOH (1, Hbhbz-3,5-di(tert-butyl)-4-hydroxybenzoic acid); an isostructural zinc complex (2); a and magnetically diluted sample of [Zn1.93Co0.07(bhbz)4(EtOH)2]·4EtOH (3) were obtained. Molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction. DFT calculations for 1 indicate strong Co-Co antiferromagnetic exchange interactions in the binuclear fragment. It was shown that when one paramagnetic ion in the binuclear molecule is replaced by a diamagnetic zinc(II) ion, the remaining cobalt(II) ion can be considered as an isolated center with magnetic anisotropy, the parameters of which are determined by ab initio calculations. Magnetic properties for samples 1 and 3 were investigated and analyzed in detail.

Complexes of Silver 1,1,1,5,5,6,6,6-Octafluorohexane-2,4-dionate with π-Donor Ligands: Synthesis, Structure, and Thermal Properties

Two new Ag(I) complexes with 1,1,1,5,5,6,6,6-octafluorohexane-2,4-dionate ion (Ofhac) and π‑donor neutral ligands, vinyltriethylsilane (VTES) or cycloocta-1,5-diene (COD), were synthesized with the goal to expand the library of silver precursors for chemical vapor deposition. The products were characterized by elemental analysis and IR and NMR spectroscopy. The complex [Ag(VTES)(Ofhac)] (I) was liquid under standard conditions; the temperature of its crystallization was below –20°C. Treatment of I with benzene gave rise to crystals of [Ag4(C6H6)2(Ofhac)4]∞ (II), which was confirmed by NMR and X-ray diffraction (CCDC no. 2232810). The structure of [Ag(COD)(Ofhac)]2 (III) was established by X-ray diffraction (CCDC no. 2232809). The binuclear molecules are formed due to the μ2-κ1(O):κ1(O') function of the Ofhac ligands (Ag–O, 2.458(2)–2.461(2) Å), while COD is κ2-η2:η2-coordinated (Ag–C, 2.420(17)–2.684(11) Å). The thermal properties of I and III in comparison with analogues containing 1,1,1,5,5,5-hexafluoropentane-2,4-dionate ion (Hfac) were studied by thermogravimetry.

A New Structural Type of Bismuth(III) Dithiocarbamato-Chlorido Complexes: Preparation, Structural Organization, and Thermal Behavior of Binuclear Compounds [Bi2{S2CN(CH2)6}4(μ2-Cl)2] and [Bi2{S2CN(CH2)6}4(μ2-Cl)2]·2CH2Cl2

Heteroleptic compounds of bismuth(III) adopting a new binuclear structural type: hexamethylenedithiocarbamato(HmDtc)-chloride of [Bi2(S2CNHm)4(μ2-Cl)2] (I) and its solvated form [Bi2(S2CNHm)4(μ2-Cl)2]·2CH2Cl2 (II) have been isolated and studied by X-ray diffraction, IR spectroscopy, and simultaneous thermal analysis. Despite the identical chemical composition, the structure of binuclear molecules in I and II differs significantly. In the first case, the noncentrosymmetric molecule includes two nonequivalent moieties of [Bi(S2CNHm)2Cl], which are combined by μ2-Cl ligands to form the [Bi–(μ2-Cl)2–Bi] metallocycle in the butterfly conformation: Bi(1)–Bi(2) 4.0785(5) Å, Cl(1)–Cl(2) 3.936(2) Å. On the contrary, in the solvated form II, the complex is centrosymmetric and four-membered [Bi2Cl2] ring is stabilized in a rhombic configuration: Bi(1)–Bi(1)a 3.9592(9) Å and Cl(1)–Cl(1)a 4.540(4) Å. According to the microprobe method, the main residual substance after the thermolysis of the complexes is microcrystalline Bi2S3 with inclusions of metallic bismuth particles.

Synthesis, characterization, crystal structures and thermochemical properties of five lanthanide complexes with mononuclear and binuclear structures

Five new lanthanide complexes were synthesized by two different experimental methods: two mononuclear complexes and three binuclear complexes. Their chemical formula is: [Gd(2-Cl-4-FBA)3(terpy)H2O]1.5H2O(1); [Dy(2-Cl-4-FBA)3(terpy)H2O]·0.5H2O(2)) (2-Cl-4-FBA = 2-chloro- 4-fluorobenzoate,terpy = 2,2′:6′,2″-terpyridine); [Ln(3,4-DFBA)3(5,5′-DM-2,2′-bipy)(H2O)]2(Ln = Pr(3),Er(4);[Ln(3,4-DFBA)3(5,5′-DM-2,2′-bipy)]2(Ln = Ho(5)) (3,4-DFBA = 3, 4-difluorobenzoate,5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridine). A series of characterization and properties of the complexes were studied, such as elemental analysis, single crystal X-ray diffraction, thermogravimetric analysis, fluorescence properties and so on. The coordination number of complexes 1–2 is 9, showing a muffin geometry. The results show that complex 1–5 crystallized in the triclinic system and space group Pī. Complexes 1 and 2 are isostructural except for the number of free water molecules. Complexes 3–5 are binuclear molecules with different structures. Although the structures of the five complexes are different, they all form one and two-dimensional supramolecular structures along a chain and a plane. The thermal decomposition mechanism of complexes 1–5 was studied by synchronous thermal analyzer infrared spectroscopy (TG/DSC-FTIR). The results show that the coordination water, neutral ligand and acidic ligand are lost in turn when the complex undergoes thermal decomposition. And the three-dimensional infrared images of gas escaping during the thermogravimetric process were analyzed. In addition, the solid state fluorescence spectra of complex 2 was measured and the results showed that the characteristic fluorescence of Dy(III) ion was emitted.

Окисление трис(2-метокси-5-бромфенил)сурьмы трет-бутилгидропероксидом в присутствии соединений, содержащих подвижный атом водорода

Oxidation of tris(2-methoxy-5-bromophenyl)antimony with tertiary butylhydroperoxide in the presence of water, benzoic acid, 2,6-dihydroxybenzoic acid and 2-chloro-4-fluorophenol in diethyl ether leads to formation of tris(2-methoxy-5-bromophenyl)antimony oxide (1), tris(2-methoxy-5-bromophenyl)antimony dibenzoate (2), -oxo[hexakis(2-methoxy-5-bromophenyl)-bis(2,6-dihydroxybenzoato)diantimony] (3), -oxo[hexakis(2-methoxy-5-bromophenyl)-bis(2-chloro-4-fluorophenoxo)diantimony] (4), respectively. The compounds have been identified by X-ray diffraction analysis. According to the X-ray diffraction data, the crystal of solvate 1 with chloroform consists of centrosymmetric binuclear molecules containing the Sb2O2 cycle with tetragonal coordination of the antimony atoms (the Sb–O bond lengths are 1.961(4) and 2.041(5) Å, the Sb–C distances are 2.114(6)–2.153(6) Å). In solvate 2 with benzene the antimony atoms have a distorted trigonal-bipyramidal coordination with the oxygen atoms of carboxylate ligands in axial positions (Sb–O 2.075(4), 2.105(4) Å), the carbonyl oxygen atoms are coordinated with the central metal atom (Sb∙∙∙O=C 3.023(6), 3.077(8) Å), the Sb–C bond lengths (2.104(5)–2.112(5) Å) are significantly less than in 1. The ranges of variation in the Sb–C bond lengths in the practically linear binuclear molecule of solvate 3 with acetonitrile are 2.101(5)–2.106(5) and 2.100(5)–2.104(5) Å (the SbOSb angle equals 178.05(18)). The bond lengths of antimony atoms with the bridging oxygen atom (1.925(4), 1.936(4) Å) are less than the sum of the covalent radii of antimony and oxygen, as well as the distances between the antimony atom and the terminal carboxyl ligand (Sb–O 2.263(4), 2.214(4) Å). The carbonyl oxygen atoms are coordinated with the central metal atom (Sb∙∙∙O=C 3.484(8), 3.512(9) Å) to a lesser extent than in 2. The crystal of solvate 4 with benzene contains two types of crystallographically independent corner molecules (the SbOSb angles are 163.75(18), 164.27(19)), the difference in lengths of the Sb–Obridge (1.939(11)–1.981(13) Å) and Sb–Oterm (2.096(11)–2.208(11) Å) is not as sharp as in the case of complex 3. Complete tables of atom coordinates, bond lengths and valence angles are deposited at the Cambridge Crystallographic Data Center (No. 2070383 (1); No. 2074511 (2); No. 1970910 (3); No. 2064392 (4); deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/data_request/cif).

Two structural types of dithiocarbamato-chlorido complexes of mercury(II): Preparation, supramolecular self-assembly, solid-state 13C and 15N NMR characterisation and thermal behaviour of pseudo-polymeric compounds of [Hg2(S2CNBu2)2Cl2] and [Hg4(S2CNiBu2)6][Hg2Cl6

Two new crystalline dithiocarbamato-chlorido complexes of mercury(II), [Hg2{S2CN(C4H9)2}2Cl2] (1) and [Hg4{S2CN(iso-C4H9)2}6][Hg2Cl6] (2), have been prepared and chemically identified by solution (1H, 13C) NMR and solid-state (13C, 15N) CP-MAS NMR and FT-IR spectroscopy. The crystal, molecular and supramolecular structures of these compounds were established using single-crystal X-ray diffraction (XRD) analysis. The obtained complexes reveal two principally different types of structural organisation. In the structure of the former neutral complex, there are two isomeric doubly-bridged binuclear molecules [Hg2(S2CNBu2)2Cl2] (‘A’ and ‘B’), whereas the latter compound comprises two ionic structural moieties: the tetranuclear cation [Hg4(S2CNiBu2)6]2+ and the binuclear anion [Hg2Cl6]2−. In both ionic units, pairs of iBu2Dtc or chloride ligands, which perform a bridging structural function, combine with neighbouring mercury atoms. In turn, intermolecular/interionic secondary interactions Hg···S/Hg···Cl are involved in the formation of supramolecular structures of complexes 1/2, yielding pseudo-polymeric chains of (···‘A’···‘B’···)n/(···[Hg4(S2CNiBu2)6]···[Hg2Cl6]···)n, which exhibit alternation of isomeric molecules of 1/ionic moieties of 2 along their lengths. Despite the significant structural difference between the above complexes, we established, using simultaneous thermal analysis (STA), that both exhibit very similar thermal behaviour. Moreover, during the thermal transformations of both compounds 1 and 2, the same two substances are generated: HgCl2 and HgS.

Synthesis and structural characterization of lanthanide metal complexes by 2-fluorobenzoic acid with 2,2′:6′,2″-terpyridine, and their fluorescence properties

Three new lanthanide complexes were synthesized by conventional solution synthesis at room temperature with the formula of [Ln(2-FBA)2(terpy)(NO3)(H2O)]·(terpy)·H2O(Ln=Dy(1)), [Ln(2-FBA)3terpy]2·2(2-FHBA)·2H2O(Ln=Pr(2),Tb(3)), (2-FBA=2-fuorobenzoate, terpy=2,2′:6′,2″-terpyridine). The complexes were characterized by elemental analysis, X-ray single crystal diffraction and infrared spectroscopy. The coordination number of complexes 1–3 is 9, showing a muffin geometry. Complex 1 is mononuclear, crystallized in the monoclinic system and space group P21/c . Complexes 2 and 3 are binuclear molecules of isomorphous, and their adjacent structural units form 1D chain and 2D sheets structure through C-H···F hydrogen bonding and π-π stacking interactions. In addition, the solid state fluorescence spectra of complexes 1 and 3 were measured. The test shows that complex 3 emits strong green light. The thermal decomposition mechanism of the complexes was studied by synchronous thermal analyzer infrared spectroscopy TG-DSC/FTIR and the 3D stacked plots of the escape gases were analyzed.

Crystal structure and Hirshfeld surface analysis of di-μ-chlorido-bis-[(aceto-nitrile-κN)chlorido-(ethyl 5-methyl-1H-pyrazole-3-carboxyl-ate-κ2 N 2,O)copper(II)

The title compound, [Cu2Cl4(C5H10N2O2)2(CH3CN)2] or [Cu2(μ2-Cl)2(CH3-Pz-COOCH2CH3)2Cl2(CH3CN)2], was synthesized using a one-pot reaction of copper powder, copper(II) chloride dihydrate and ethyl 5-methyl-1H-pyrazole-3-carboxyl-ate (CH3-Pz-COOCH2CH3) in aceto-nitrile under ambient conditions. This complex consists of discrete binuclear mol-ecules with a {Cu2(μ2-Cl)2} core, in which the Cu⋯Cu distance is 3.8002 (7) Å. The pyrazole-based ligands are bidentate coordinated, leading to the formation of two five-membered chelate rings. The coordination geometry of both copper atoms (ON2Cl3) can be described as distorted octa-hedral on account of the aceto-nitrile coordination. A Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H⋯H (40%), H⋯Cl/Cl⋯H (24.3%), H⋯O/O⋯H (11.8%), H⋯C/C⋯H (9.2%) and H⋯N/N⋯H (8.3%) inter-actions.

BONDING FEATURES BETWEEN 2-PHENYLPYRIDINE AND 3d METAL IONS IN POLYNUCLEAR PIVALATES

The effect of a bulky phenyl substituent on the formation and stability of pivalate complexes of 3d transition metals is studied on the example of 2-phenylpyridine (phpy). Quantum chemical calculations in the B3LYP/Def2-TZVP approximation are used to optimize binuclear molecules of [M2(μ-piv)4L2] complexes, where M = Co, Ni, Cu, $$\text{piv} = \text{Me}_3\text{CCO}^-_2$$ , L = 2,3-lutidine (lut) for which the analyzed compounds are known, phpy, and 7,8-benzoquinoline (bquin). The calculated energy characteristics indicate a significant stability of lut complexes and suggest that similar compounds with phpy can be prepared. The accuracy of theoretical calculations is confirmed by the successful synthesis of complex [Cu2(piv)4(phpy)2] (3). The computational simulation of binuclear coordination compounds with bquin suggests that there is a theoretical possibility of their formation; however, the fact that such structures have lower stabilization energies than those of reference complexes ([M2(piv)4(DMF)2]) indicates that their preparative isolation is hindered. Molecular structures of novel molecular complexes [Ni9(OH)6(piv)12(Hpiv)2(phpy)]·C6H6 (2) and [Li2Co2(piv)6(phpy)2] (4) are isolated and determined.

Bi(III) Complexes Containing Dithiocarbamate Ligands: Synthesis, Structure Elucidation by X‐ray Diffraction, Solid‐State 13C/15N NMR, and DFT Calculations

AbstractWe report on syntheses, characterisation by nuclear magnetic resonance (NMR) spectroscopy, X‐ray diffraction (XRD) measurements, and density functional theory (DFT) calculations of electronic/molecular structure and NMR chemical shifts of complexes of Bi(III), having the molecular formulae: [Bi{S2CN(C2H5)2)}3] (1), [Bi{S2CN(C2H5)2)}2(C12H8N2)NO3)] (2), and [Bi2{S2CN(CH2)5}6 H2O] (3). The powder XRD patterns of complexes (1) and (2) resembled the corresponding calculated powder XRD patterns for previously reported single crystal structures. Single crystal XRD structure of complex (3), reported in this work, adopted an orthorhombic system with a space group Pbca with a=10.9956(3) Å, b=27.7733(8) Å, c=35.1229(10) Å and α=β=γ=90°. The experimental solid‐state 13C/15N NMR data of the complexes (1)‐(3) were in accord with their X‐ray single crystal structures. The unit cell of the complex (3) shows a weak supramolecular Bi S interaction leading to the formation of a non‐centrosymmetric binuclear molecule [Bi2{S2CN(CH2)5}6 H2O], which displays structural inequivalence in both 13C/15N NMR, and XRD data. Assignments of resonance lines in solid‐state 13C/15N NMR spectra of complexes (1)‐(3) were assisted by chemical shift calculations using periodic DFT methods. The findings of the present multidisciplinary approach will contribute in designing molecular models and further understanding of the structures and properties of (diamagnetic) metal complexes, including heavy metal ones.

Electro-vibrational Ising-type model for spin crossover in binuclear molecules

A spin crossover in binuclear molecule is investigated using an Ising-type model, including the intramolecular vibrations. The spin transition curve of [Fe(bt)(NCS)2]2bpym complex which presents a two-step transition plateau is well described by the above model. We show that the equilibrium low-spin/high-spin temperature $$ T_{\text{eq}} $$ is independent of the vibration frequencies of the intermediate state (HS–LS or LS–HS) $$ \omega_{\text{LHS}} $$ . In addition, a large values of LS–LS state vibration frequencies $$ \omega_{\text{LLS}} $$ lead to an evident two-step transition plateau.

Multiresponsive Spin Crossover Driven by Rotation of Tetraphenylborate Anion in an Iron(III) Complex

Dynamic molecular materials, which involve mechanical motions in crystals, usually exhibit tunable properties related to conformational polymorphs. Herein, we describe a solvent-free molecular crys...

Syntheses, crystal structures and properties of four metal coordination complexes constructed from aromatic carboxylate and benzimidazole-based ligands

Four metal–organic coordination complexes, namely {[Zn(SIP)(mbi)2]·(Hmbi)·(H2O)2}n (1), {[Cd3(SIP)2(bbhb)3(H2O)4]·(H2O)2}n (2), [Co3(SIP)2(bbhb)4(H2O)2]n (3) and [Zn2(NIPA)2(mbi)2(H2O)3] (4) (H3SIP = 5-sulfoisophthalic acid, mbi = 2-methylbenzimidazole, bbhb = 1,1′-(1,4-butanediyl)bis-1H-benzimidazole and H2NIPA = 5-nitroisophthalic acid), have been hydrothermally synthesized. Single-crystal X-ray analyses show that these complexes have different structural features. In complex 1, the SIP3− anions bridge Zn(II) atoms to form 1D right-handed helical chains, which are further interconnected by hydrogen-bond interactions, forming a 3D supramolecular architecture. In complex 2, the Cd1 and Cd2 atoms are bridged by SIP3− ligands to form 1D chains, which are extended to 2D layer with Cd3 atoms as hinges. The 2D layers are further connected by bbhb ligands to give a 3D framework. The Co(II) atoms in compound 3 are bridged by SIP3− anions to generate 1D ladder-like chain; then, the 1D chains extend to 2D network by the connection of “L”-shaped bbhb ligands. Finally, the 2D networks are bridged by “S”-shaped bbhb ligands to give rise to the formation of 3D framework. In compound 4, the binuclear molecules are connected through hydrogen bonds to generate a 2D layer. The results illustrate that the carboxylate ligands and the versatile conformations of the bbhb ligands contribute to the structural diversity of these complexes. The photoluminescent properties of complexes 1, 2 and 4 are also studied.

A binuclear CuII/CaII thio-cyanate complex with a Schiff base ligand derived from o-vanillin and ammonia.

The new heterometallic complex, aqua-1κO-bis-(μ2-2-imino-methyl-6-meth-oxy-phenolato-1κ2 O 1,O 6:2κ2 O 1,N)bis-(thio-cyanato-1κN)calcium(II)copper(II), [CaCu(C8H8NO2)2(NCS)2(H2O)], has been synthesized using a one-pot reaction of copper powder, calcium oxide, o-vanillin and ammonium thio-cyanate in methanol under ambient conditions. The Schiff base ligand (C8H9NO2) is generated in situ from the condensation of o-vanillin and ammonia, which is released from the initial NH4SCN. The title compound consists of a discrete binuclear mol-ecule with a {Cu(μ-O)2Ca} core, in which the Cu⋯Ca distance is 3.4275 (6) Å. The coordination geometries of the four-coordinate copper atom in the [CuN2O2] chromophore and the seven-coordinate calcium atom in the [CaO5N2] chromophore can be described as distorted square planar and penta-gonal bipyramidal, respectively. In the crystal, O-H⋯S hydrogen bonds between the coordinating water mol-ecules and thio-cyanate groups form a supra-molecular chain with a zigzag-shaped calcium skeleton.

Photosensitive Tin Sulfur Dioxide Complexes with Unexpected Bonding Modes.

Infrared spectra of the matrix-isolated Sn(η2 -O2 S), Sn(η2 -OSO), Sn(η2 -O2 S)(η1 -OSO), Sn(η2 -O2 S)2, OSn2 (η2 -SO), and Sn(μ2 -O2 )SnS molecules were observed following laser-ablated Sn atom reactions with SO2 during condensation in solid argon. The assignments for the major vibrational modes were confirmed by appropriate S18 O2 and 34 SO2 isotopic shifts and density functional vibrational frequency calculations (B3LYP and BPW91). Interestingly, the mononuclear complexes are interconvertible; that is, irradiation induces the isomerization of Sn(η2 -O2 S) and Sn(η2 -O2 S)(η1 -OSO) to Sn(η2 -OSO) and Sn(η2 -O2 S)2 , respectively, and vice versa on annealing. However, there is no evidence of isomerization reaction in between the binuclear molecules OSn2 (η2 -SO) and Sn(μ2 -O2 )SnS. Bonding in these products is discussed, and the electronic structure changes associated with different bonding types are revealed, which is crucial for the observed photochemical reactions.

A new structural motif for cadmium dithiocarbamates: crystal structures and Hirshfeld surface analyses of homoleptic zinc and cadmium morpholine dithiocarbamates

Abstract The crystal and molecular structures of two homoleptic morpholine-derived dithiocarbamates of zinc, binuclear {Zn[S2CN(CH2CH2)2O)2]2}2 (1), and cadmium, one-dimensional coordination polymer {Cd[S2CN(CH2CH2)2O)2]2}2 (2), are described. In 1, a centrosymmetric binuclear molecule is found as there are equal numbers of chelating and bidentate bridging dithiocarbamate ligands; weak transannular Zn···S interactions are found within the resultant eight-membered {···SCSZn}2 ring which has the form of a chair. The resultant 4+1 S5 donor set is highly distorted with the geometry tending towards a square-pyramid. By contrast, a square-planar geometry is found in centrosymmetric 2 defined by symmetrically chelating dithiocarbamate ligands. The presence of Cd···S secondary bonding in the crystal of 2 leads to a distorted 4+2 S6 octahedron and a linear coordination polymer, which is unprecedented in the structural chemistry of cadmium dithiocarbamates. The analyses of the Hirshfeld surfaces for 1 and 2 show the dominance of H···H, S···H/H···S and O···H/H···O contacts to the surface, i.e. contributing around 90 and 80%, respectively.

Crystal Structure and Luminescence of a Novel Binuclear Zinc(II) Complex with Di-2-Pyridylamine And 4,4′-Sulfonyldibenzoate

A binuclear Zn(II) complex [Zn2(SDBA)2(DPA)2.2H2O] (1) (DPA = di-2-pyridylamine, H2SDBA = 4,4′- sulfonyldibenzoic acid) is synthesized and characterized using single crystal X-ray diffraction, IR spectroscopy, and elemental analysis. The single crystal X-ray diffraction analysis reveals that complex 1 is a binuclear zinc(II) complex. The binuclear molecules are further connected by three types of N–H...O, C–H...O, and O–H...O hydrogen bonds, generating a three-dimensional supramolecular structure. Meanwhile, S–O...π interactions further consolidate the three-dimensional supramolecular framework of 1. In addition, the thermal stability and luminescent properties of the title complex are briefly investigated. The luminescence measurements reveal that complex 1 exhibits fluorescent emission in the solid state at room temperature.

Asymmetric Oxygen Bridged Copper(II) Carboxylate: Synthesis, Complete Characterization, and Crystal Structure

Binuclear centrosymmetric copper(II) complex of the formula bipyCu(L)4Cubipy, where bipy = 2,2′- bipyridine and L = 4-methoxy-2-phenyl acetate, is synthesized and characterized by FT-IR, UV-Visible, ESR and mass spectroscopy, electrochemical, thermogravimetric, and single crystal XRD techniques. The complex contains two differently oriented molecules per unit cell stabilized via intermolecular interactions. Geometry around each Cu(II) was found to be square pyramidal affected by asymmetrically bridging oxygen atoms occupying the apical position of one square pyramid and the axial position of another in the same binuclear molecule. The square base is formed by two oxygen atoms from two carboxylate ligands and two nitrogen atoms from the bipyridine moiety. TGA shows that the complex is stable up to 170 °C followed by stepwise loss of coordinated ligands, which was supported by GC-MS data as well. A broad absorption spectrum indicated 2B1g as the ground state and single electron occupancy of the dx2–y2 orbital, which was confirmed by the ESR spectrum. The electrochemical study gives two oxidation curves corresponding to Cu(II)/Cu(III) and Cu(I)/Cu(II) and a reduction signal corresponding to the Cu(II)/Cu(I) process. The robust complex represents an interesting contribution to the understanding of coordination chemistry.

(μ-Methylenediphosphonato-κ4 O,O':O'',O''')bis[(ethyl-ene-diamine-κ2 N,N')palladium(II)] tetra-hydrate.

The title compound, [Pd2(C2H8N2)2(CH2O6P2)]·4H2O, comprises of a binuclear mol-ecule (point group symmetry 2), with a twofold rotation axis running through the central C atom of the methyl-enedi-phospho-nate (MDP) anion. The PdII atom has a square-planar coordination environment defined by the N atoms of a bidentate ethyl-enedi-amine (en) ligand and two O atoms of the bridging MDP anion. In the crystal structure, metal complexes are arranged in layers parallel (001) and are sandwiched between layers containing disordered water mol-ecules of crystallization. Extensive intra-layer hydrogen bonds of the type N-H⋯O in the metal complex layer and O-H⋯O in the water layer, as well as O-H⋯O hydrogen bonds between the two types of layers, lead to the formation a three-dimensional network structure. The two lattice water mol-ecules are each equally disordered over two positions.

μ2-Chlorido-chlorido(μ2-4-{[2-(diethylamino)ethyl]imino}pent-2-en-2-olato)bis(tetrahydrofuran-κO)cobalt(II)lithium

The crystal structure of the title compound, [CoLi(C11H21N2O)Cl2(C4H8O)2], has monoclinic symmetry and comprises one heterometallic binuclear complex molecule in the asymmetric unit. The Co2+ cation is bonded to one oxygen and two nitrogen atoms of a β-ketoiminato ligand and to two chlorido ligands, leading to a distorted trigonal-bipyramidal coordination sphere. One of the Cl ligands and the oxygen atom of the β-ketoiminato ligand are bridging to a Li+ cation, which is further bonded to oxygen atoms of two THF molecules. The resulting coordination sphere is distorted tetrahedral. In the crystal, weak intermolecular C—H...Cl hydrogen bonds are identified that link the complex molecules into a three-dimensional network structure.