Field‐Induced Single‐Ion Magnetic Behavior in Two Mononuclear Cobalt(II) Complexes

The employment of a new rigid N‐tridentate ligand, bis(1‐chloroimidazo[1,5‐a]pyridin‐3‐yl)pyridine (bcpp), in the construction of cobalt(II) single‐ion magnets is reported. Two cobalt(II) complexes, [Co(bcpp)Cl₂] ( 1 ) and [Co(bcpp)Br₂] ( 2 ), have been prepared and characterized. Single‐crystal XRD analyses reveal that complexes 1 and 2 are isostructural. They are pentacoordinated mononuclear cobalt(II) compounds with expected trigonal bipyramidal geometry. Both analysis of the magnetic data and ab initio calculations reveal easy‐plane magnetic anisotropy (D>0) for 1 and 2 . Detailed alternating current magnetic susceptibility measurements reveal the occurrence of slow magnetic relaxation behavior for the cobalt(II) centers of 1 and 2 ; thus indicating that both complexes are field‐induced single‐ion magnets.     

2‐Amino‐5‐(2‐pyridyl)‐thiadiazole as Bidentate Ligand

The amino substituted bidentate chelating ligand 2‐amino‐5‐(2‐pyridyl)‐1,3,4‐thiadiazole (H₂ L ) was used to prepare 3:1‐type coordination compounds of iron(II), cobalt(II) and nickel(II). In the iron(II) perchlorate complex [Fe^II(H₂ L )₃](ClO₄)₂·0.6MeOH·0.9H₂O a 1:1 mixture of mer and fac isomers is present whereas [Fe^II(H₂ L )₃](BF₄)₂·MeOH·H₂O, [Co^II(H₂ L )₃](ClO₄)₂·2H₂O and [Ni^II(H₂ L )₃](ClO₄)₂·MeOH·H₂O feature merely mer derivatives. Moessbauer spectroscopy and variable temperature magnetic measurements revealed the [Fe^II(H₂ L )₃]²⁺ complex core to exist in the low‐spin state, whereas the [Co^II(H₂ L )₃]²⁺ complex core resides in its high‐spin state, even at very low temperatures.     

Iron(II) and Nickel(II) Complexes of N‐Alkylimidazoles and 1‐Methyl‐1H‐1, 2, 4‐Triazole: X‐ray Studies,Magnetic Characterization,and DFT Calculations

Using the ligands N‐methylimidazole ( MeIm ), N‐ethylimidazole ( EtIm ), N‐propylimidazole ( PrIm ), and 1‐methyl‐1H‐1, 2, 4‐triazole ( MeTz ) three series with a total of 13 iron(II) complexes were isolated. The series comprise of the following complexes: (a) [Fe( MeIm )₆](ClO₄)₂ ( 1 ), [Fe( EtIm )₆](ClO₄)₂ ( 2 ), [Fe( PrIm )₆](ClO₄)₂( 3 ), [Fe( MeTz )₆](ClO₄)₂ ( 4 ), [Fe( MeIm )₆](MeSO₃)₂ ( 5 ), [Fe( EtIm )₆](MeSO₃)₂ ( 6 ), and [Fe( MeTz )₆](BF₄)₂ ( 10 ); (b) [Fe( MeIm )₄(MeSO₃)₂]( 7 ), [Fe( EtIm )₄(MeSO₃)₂] ( 8 ), and [Fe( PrIm )₄(MeSO₃)₂] ( 9 ); (c) [Fe( MeIm )₄(NCS)₂] ( 15 ), [Fe( EtIm )₄(NCS)₂] ( 16 ), and [Fe( MeTz )₄(NCS)₂] ( 17 ). Single crystal X‐ray diffraction studies were performed on 7 – 10 and 15 – 17 . Temperature dependent magnetic susceptibility measurements were performed on selective examples of all series, and confirmed them to be in the HS state over the range 6–300 K. DFT calculations were performed at BP86/def‐SV(P) and TPSSh/def2‐TZVPP level on all [Fe L ₆]²⁺ complex cations and the neutral complexes 7 – 9 and 15 – 17 . Additionally the four homoleptic nickel(II) complexes [Ni L ₆](ClO₄)₂ ( 11 : L = MeIm ; 12 : L = EtIm ; 13 : L = PrIm ; 14 : L = MeTz ) were synthesized and compounds 11 – 13 structurally characterized. UV/Vis/NIR spectroscopic measurements were carried out on all homoleptic iron(II) and nickel(II) complexes. The 10Dq values were determined to be in the range of 11547–11574 and 10471–10834 cm^–1 for the iron(II) and nickel(II) complexes, respectively.     

Diazabutadiene cobalt(II) complexes

Summary Studies on the chelates of cobalt(II) with the bidentate ligands 1,4-diphenyl(2,3-dimethyl-1,4-diazabutadiene) (PMB) and 1,4-di(p-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadiene (MPMB) have been carried out. On the basis of elemental analyses, the complexes are [Co(PMB)Cl₂], [Co(PMB)₂(C1O₄)₂], [Co(MPMB)Cl₂] and [Co(MPMB)₂(ClO₄)₂].Both ligands are bidentatevia nitrogen atoms in all the complexes. The magnetic susceptibility and i.r. and u.v.-visible spectra are reported and discussed. The chloro-compounds involving two chlorine ligands and, in the perchlorate compounds, the ClO ₄ ^– groups are bound to the cobalt(II) centre.     

Metallkomplexe mit N2O2S2‐Koordinationssphäre. Synthese und Charakterisierung der Cobalt(II)‐, Nickel(II)‐ und Kupfer(II)‐Komplexe eines 15‐ und eines 16‐gliedrigen N,N′‐bis(2‐hydroxyethyl)‐funktionalisierten makrocyclischen Liganden

Metal Complexes with N₂O₂S₂ Donor Set. Synthesis and Characterization of the Cobalt(II), Nickel(II), and Copper(II) Complexes of a 15‐ and a 16‐Membered Bis(2‐hydroxyethyl) Pendant Macrocyclic Ligand The macrocyclic ligands 6, 10‐bis(2‐hydroxyethyl)‐7, 8, 9, 11, 17, 18‐hexahydro‐dibenzo‐[e, n][1, 4, 8, 12]‐dithiadiaza‐cyclopentadecine ( 1 ) (L¹) and 5, 13‐bis(2‐hydroxyethyl)‐7, 8, 9, 10, 16, 17, 18, 19, 20‐nonahydro‐dibenzo‐[g, o][1, 9, 5, 13]‐dithiadiaza‐cyclohexadecine (L⁴) have been prepared. They form the stable complexes [CoL¹(‐H)CoL¹](ClO₄)₃ ( 2 ), [NiL¹](ClO₄)₂·MeOH ( 3 ), Λ‐[CuL¹](ClO₄)₂·MeOH ( 4a ) and rac‐[CuL¹](ClO₄)₂·MeOH ( 4b ), [NiL⁴](ClO₄)₂ ( 5 ), and [CuL⁴](ClO₄)₂ ( 6 ). The compounds 1 to 6 have been characterized by standard methods and single‐crystal X‐ray diffraction. In the complexes 2 to 6 the metal atoms are octahedrally coordinated by the N₂O₂S₂ donor set of the ligands. L¹ and L⁴ are folded herein along the N···M···S‐ and the N···M···N′‐axes, respectively. This results at the metal atom in a all‐cis‐configuration for the complexes of L¹ and a trans‐N₂‐cis‐O₂‐cis‐S₂‐configuration for the complexes of L⁴. The cobalt(II) complex 2 is a dimer, bridged by a rather short hydrogen bridge of 2.402(12)Å length. The copper(II) complexes of L¹ and L⁴ differ with respect to the Jahn‐Teller‐distortion.     

Complexes of copper(II) with diazabutadienes

Summary Studies on the chelate complexes of copper(II) with the bidentate ligands, 1,4-diphenyl-2,3-dimethyl-1,4-diazabutadiene (PMB) and 1,4-di(p-methoxyphenyl)-2,3-dimethyl-1,4-diazabutadiene (MPMB), have been carried out. On the basis of the elemental analysis and molar conductivity, the complexes have been characterized as [Cu(PMB)Cl₂], [Cu(PMB)₂](ClO₄)₂, [Cu(MPMB)Cl₂] and [Cu(MPMB)₂](ClO₄)₂. Both diazabutadienes are bidentate via nitrogen atoms. The temperature dependence of the magnetic susceptibility and the electron paramagnetic resonance, i.r. and u.v.-vis spectra are reported. All compounds appear to be monomers.     

Spectral and Structural Studies of Transition Metal Complexes of 2‐Pyridineformamide N(4)‐ethylthiosemicarbazone

The reduction of 2‐cyanopyridine in the presence of N(4)‐ethylthiosemicarbazide produces 2‐pyridineformamide N(4)‐ethylthiosemicarbazone, HAm4E. Complexes with cobalt(III), nickel(II), copper(II), palladium(II) and platinum(II) have been prepared and characterized by molar conductivity, magnetic susceptibility and spectroscopic techniques. In addition, the crystal structures of HAm4E, [Co(Am4E)₂](ClO₄), [Ni(HAm4E)₂](ClO₄)₂, and [Ni(HAm4E)₂]Cl(OAc)·AcOH·H₂O have been obtained. Coordination occurs through the pyridyl nitrogen, imine nitrogen and either the thione or thiolato sulphur atom when coordinating as the neutral or anionic ligand, respectively. Extensive hydrogen bonding occurs in both HAm4E and its metal complexes, with the amide hydrogen atoms being significant contributors.     

Synthesis, spectroscopic characterization, and antimicrobial activity of cobalt(II) complexes of acetone-N(4)-phenylsemicarbazone: crystal structure of [Co(HL)2(MeOH)2](NO3)2

Four Co(II) complexes, [Co(HL)₂](OAc)₂, [Co(HL)₂Cl₂], [Co(HL)₂(MeOH)₂](NO₃)₂, and [Co₂(HL)₄(SO₄)₂] (HL = acetone-N(4)-phenylsemicarbazone) were synthesized and characterized by physicochemical and spectroscopic methods. The magnetic susceptibility measurements indicate that the complexes are paramagnetic with three unpaired electrons. In all the complexes, the semicarbazone is coordinated as a neutral bidentate ligand. The structure of [Co(HL)₂(MeOH)₂](NO₃)₂ was confirmed by single crystal X-ray crystallography. The ligand is neutral and bidentate, being coordinated to the cobalt atom through the carbonyl oxygen and the azomethine nitrogen. Intermolecular hydrogen bonding and C–H···π interactions combine to stabilize the crystal structure. The ligand and its two complexes [Co(HL)₂Cl₂] and [Co(HL)₂(MeOH)₂](NO₃)₂ were screened for their antibacterial and antifungal activities using disk diffusion methods.     

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and its Complexes with Copper(II) Chloride and Copper(II) Perchlorate

1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole (hnt), prepared by alkylation of 3‐nitro‐1, 2, 4‐triazole with 2‐chloroethanol, was found to react with copper(II) chloride and copper(II) perchlorate in acetonitrile/ethanol solutions giving complexes [Cu₂(hnt)₂Cl₄(H₂O)₂] and[Cu(hnt)₂(H₂O)₃](ClO₄)₂, respectively. They are the first examples of coordination compounds with a neutral N‐substituted 3‐nitro‐1, 2, 4‐triazole ligand. 1‐(2‐Hydroxyethyl)‐3‐nitro‐1, 2, 4‐triazole and the obtained complexes were characterized by NMR and IR spectroscopy, X‐ray, and thermal analyses. [Cu₂(hnt)₂Cl₄(H₂O)₂] presents a dinuclear chlorido‐bridged complex in which hnt acts as a chelating bidentate ligand, coordinated to the metal by a nitrogen atom of the triazole ring and an oxygen atom of the nitro group, and the copper atoms are inconsiderably distorted octahedral coordination. [Cu(hnt)₂(H₂O)₃](ClO₄)₂comprises a mononuclear complex cation, in which two nitrogen atoms of two hnt ligands in trans configuration and three water oxygen atoms form a square pyramidal environment around the copper atom, which is completed to an distorted octahedron with a bifurcated vertex due to two additional elongated Cu–O bonds with two nitro groups. In both complexes, Cu–O bonds with the nitro groups may be considered as semi‐coordinated.     

Cyano­cobalt(III) complexes of penta‐ and tetra­dentate‐coordinated macrocyclic hexa­amines

The pendent‐arm macrocyclic hexa­amine trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diamine (L) may coordinate in tetra‐, penta‐ or hexa­dentate modes, depending on the metal ion and the synthetic procedure. We report here the crystal structures of two pseudo‐octa­hedral cobalt(III) complexes of L, namely sodium trans‐cyano­(trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diamine)cobalt(III) triperchlorate, Na[Co(CN)(C₁₃H₃₀N₆)](ClO₄)₃ or Na{trans‐[CoL(CN)]}(ClO₄)₃, (I), where L is coordinated as a penta­dentate ligand, and trans‐dicyano­(trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diamine)cobalt(III) trans‐dicyano­(trans‐6,13‐dimethyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐6,13‐diaminium)cobalt(III) tetra­perchlorate tetra­hydrate, [Co(CN)₂(C₁₄H₃₂N₆)][Co(CN)₂(C₁₄H₃₀N₆)](ClO₄)₄·4H₂O or trans‐[CoL(CN)₂]trans‐[Co(H₂L)(CN)₂](ClO₄)₄·4H₂O, (II), where the ligand binds in a tetra­dentate mode, with the remaining coordination sites being filled by C‐­bound cyano ligands. In (I), the secondary amine Co—N bond lengths lie within the range 1.944 (3)–1.969 (3) Å, while the trans influence of the cyano ligand lengthens the Co—N bond length of the coordinated primary amine [Co—N = 1.986 (3) Å]. The Co—CN bond length is 1.899 (3) Å. The complex cations in (II) are each located on centres of symmetry. The Co—N bond lengths in both cations are somewhat longer than in (I) and span a narrow range [1.972 (3)–1.982 (3) Å]. The two independent Co—CN bond lengths are similar [1.918 (4) and 1.926 (4) Å] but significantly longer than in the structure of (I), again a consequence of the trans influence of each cyano ligand.     

Heterodinuclear Ruthenium(II) Complexes of the Bridging Ligand 1,6,7,12‐Tetraazaperylene with Iron(II), Cobalt(II), Nickel(II), as well as Palladium(II) and Platinum(II)

The first heterodinuclear ruthenium(II) complexes of the 1,6,7,12‐tetraazaperylene (tape) bridging ligand with iron(II), cobalt(II), and nickel(II) were synthesized and characterized. The metal coordination sphere in this complexes is filled by the tetradentate N,N′‐dimethyl‐2,11‐diaza[3.3](2,6)‐pyridinophane (L‐N₄Me₂) ligand, yielding complexes of the general formula [(L‐N₄Me₂)Ru(µ‐tape)M(L‐N₄Me₂)](ClO₄)₂(PF₆)₂ with M = Fe {[ 2 ](ClO₄)₂(PF₆)₂}, Co {[ 3 ](ClO₄)₂(PF₆)₂}, and Ni {[ 4 ](ClO₄)₂(PF₆)₂}. Furthermore, the heterodinuclear tape ruthenium(II) complexes with palladium(II)‐ and platinum(II)‐dichloride [(bpy)₂Ru(μ‐tape)PdCl₂](PF₆)₂ {[ 5 ](PF₆)₂} and [(dmbpy)₂Ru(μ‐tape)PtCl₂](PF₆)₂ {[ 6 ](PF₆)₂}, respectively were also prepared. The molecular structures of the complex cations [ 2 ]⁴⁺ and [ 4 ]⁴⁺ were discussed on the basis of the X‐ray structures of [ 2 ](ClO₄)₄ · MeCN and [ 4 ](ClO₄)₄ · MeCN. The electrochemical behavior and the UV/Vis absorption spectra of the heterodinuclear tape ruthenium(II) complexes were explored and compared with the data of the analogous mono‐ and homodinuclear ruthenium(II) complexes of the tape bridging ligand.     

Synthesis and characterization of new complexes of some divalent transition metals with 2-acetyl-pyridyl-isonicotinoylhydrazone

Ten new mononuclear complexes having general formulae [ML₂](ClO₄)₂, M = Cu(II), Co(II), Ni(II), Mn(II) and Zn(II), [ML₂](SO₄), M = Co(II), Ni(II) and [ML₂(H₂O)₂](SO₄), M = Cu(II), Mn(II) and Zn(II), L = 2-acetyl-pyridyl-isonicotinoylhydrazone have been synthesized and characterized based on elemental analyses, IR spectroscopy, UV–Vis–NIR, EPR, as well as thermal analysis and determination of molar conductivity and magnetic moments. The structures of [CoL₂](ClO₄)₂ are accomplished by single crystal X-ray diffraction. The coordination sphere is formed by two N, N, O tridentates 2-acetyl-pyridyl-isonicotinoylhydrazone ligands, or by two N, O bidentate 2-acetyl-pyridyl-isonicotinoylhydrazone and two water molecules. Biological activity studies reveal a moderate activity of complexes against gram-negative and gram-positive bacteria.     

Cobalt(II,III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine

A new series of cobalt(II, III) and copper(II) complexes of 3-(2-furylidene) hydrazino-5,6-diphenyl-1,2,4-triazine (L) having formulae LM^IIX₂, L₂M^IIX₂ and LCo^IIIX₃, (X = Cl, OAc or ClO₄; M^II = Co^II or Cu^II) were isolated and characterized by elemental analyses, molar conductances, magnetic moments and i.r., electronic and e.s.r. spectral measurements. The i.r. spectra indicated that the ligand, L, behaves as a neutral bidentate towards divalent metal ions via a triazine-N, and azomethine-N, and acts as a tridentate towards cobalt(III) via the same two nitrogen atoms and the furan-O. The magnetic moments and electronic spectral data suggest a pseudo-tetrahedral geometry for [L₂Co]Cl₂, a diamagnetic tetragonally distorted octahedral geometry for [LCoCl₃], [LCo(OAc)₃] · 4H₂O and [LCo(H₂O)₃](ClO₄)₃ and a dimeric square pyramidal geometry for both [LCuCl₂] and [LCu(OAc)₂] · 2H₂O through bridged chloro and acetato ligands, respectively. The ligand field parameters (B, 10Dq and ) were evaluated from the electronic spectral data and magnetic moments and related to the bonding of the complexes. The X-band e.s.r. spectra showed three g values with large magnetic anisotropy for [L₂Co]Cl₂ in accordance with pseudo-tetrahedral Co^II complexes; axial pattern for [LCuCl₂], [LCu(OAc)₂] · 2H₂O and [L₂Cu(H₂O)₂](ClO₄)₂ with two g values and a signal due to M _s = ±2 transition for both chloro and acetato copper(II) complexes.     

Two 2,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazo­le–metal complexes (M = Cu and Ni)

The reaction of the diazine ligand 3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazole (pod, C₁₂H₈N₄O), with Cu(CF₃SO₃)₂ or Ni(ClO₄)₂ afforded the title complexes di­aqua­bis­[3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazole‐N²,N³]copper(II) bis­(tri­fluoro­methane­sul­fon­ate), [Cu(pod)₂(H₂O)₂](CF₃SO₃)₂, and di­aqua­bis­[3,5‐bis(2‐pyridinyl)‐1,3,4‐oxa­diazo­le‐N²,N³]­nickel(II) diperchlorate, [Ni(pod)₂(H₂O)₂](ClO₄)₂. Both complexes present a crystallographically centrosymmetric mononuclear cation structure which consists of a six‐coordinated Cu^II or Ni^II ion with two pod mol­ecules acting as bidentate ligands and two axially coordinated water mol­ecules.     

Synthesis,Spectral Characterization and Antimicrobial Activity of Some Transition Metal Complexes of 1,3‐Bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane

1,3‐Bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane ( L ) complexes with Fe(NO₃)₃, CoCl₂, Co(NO₃)₂, Ni(NO₃)₂, CuCl₂, Cu(ClO₄)₂, PdCl₂, CdI₂, Hg(NO₃)₂ were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT‐IR, NMR, ESI‐MS, fluorescence spectroscopy. Also, the crystal structure of 1,3‐bis(1H‐benzimidazol‐2‐yl)‐2‐oxapropane]dichlorocobalt(II), [Co( L )Cl₂], complex is reported that it has distorted trigonal bipyramidal geometry. Antibacterial activities of the compounds were evaluated using the disk diffusion method against six bacteria and Candida albicans. The Hg(II) complex shows superior activity toward S. epidermidis and E. coli whereas the other complexes are ineffective except the Co(NO₃)₂ complex: it showed weak activity toward all of the microorganisms.     

Oxamido‐bridged N4 Macrocyclic Complexes CuII/MII/CuII (M = Mn,Co): Synthesis,Crystal Structures and Magnetic Properties

Two new oxamido‐bridged N₄ macrocyclic complexes [(CuL)₂Mn(C₂H₅OH)₂](ClO₄)₂ · 2C₂H₅OH ( 1 ) and [(CuL)₂Co‐(C₂H₅OH)₂](ClO₄)₂ · 2C₂H₅OH ( 2 ) (H₂L = 2,3‐dioxo‐5,6:14,15‐di‐benzo‐7,13‐diphenyl‐1,4,8,12‐tetraazacyclo‐pentadeca‐7,13‐diene) have been synthesized and structurally characterized by X‐ray crystallographic investigations. In the two complexes, all copper(II) ions adopt a slightly distorted square‐planar configuration and the central manganese(II) and cobalt(II) ions are set in a distorted octahedral coordination sphere, connected to the other CuL fragments through exo‐cis oxamido bridges. The analyses of the magnetic properties were carried out by means of the theoretical expression of the magnetic susceptibility deduced from the spin Hamiltonian ? = –2J?₁?₂, leading to J = –14.58 cm^–1 for complex 1 and J = –26.95 cm^–1 for complex 2 , respectively.     

Cobalt(II) chloride adducts with acetonitrile,propan‐2‐ol and tetrahydrofuran: considerations on nuclearity,reactivity and synthetic applications

High‐spin cobalt(II) complexes are considered useful building blocks for the synthesis of single‐molecule magnets (SMM) because of their intrinsic magnetic anisotropy. In this work, three new cobalt(II) chloride adducts with labile ligands have been synthesized from anhydrous CoCl₂, to be subsequently employed as starting materials for heterobimetallic compounds. The products were characterized by elemental, spectroscopic (EPR and FT–IR) and single‐crystal X‐ray diffraction analyses. trans‐Tetrakis(acetonitrile‐κN )bis(tetrahydrofuran‐κO )cobalt(II) bis[(acetonitrile‐κN )trichloridocobaltate(II)], [Co(C₂H₃N)₄(C₄H₈O)₂][CoCl₃(C₂H₃N)]₂, (1), comprises mononuclear ions and contains both acetonitrile and tetrahydrofuran (thf) ligands, The coordination polymer catena‐poly[[tetrakis(propan‐2‐ol‐κO )cobalt(II)]‐μ‐chlorido‐[dichloridocobalt(II)]‐μ‐chlorido], [Co₂Cl₄(C₃H₈O)₄], (2′), was prepared by direct reaction between anhydrous CoCl₂ and propan‐2‐ol in an attempt to rationalize the formation of the CoCl₂–alcohol adduct (2), probably CoCl₂(HOⁱPr)_m . The binuclear complex di‐μ‐chlorido‐1:2κ⁴Cl :Cl‐dichlorido‐2κ²Cl‐tetrakis(tetrahydrofuran‐1κO )dicobalt(II), [Co₂Cl₄(C₄H₈O)₄], (3), was obtained from (2) after recrystallization from tetrahydrofuran. All three products present cobalt(II) centres in both octahedral and tetrahedral environments, the former usually less distorted than the latter, regardless of the nature of the neutral ligand. Product (2′) is stabilized by an intramolecular hydrogen‐bond network that appears to favour a trans arrangement of the chloride ligands in the octahedral moiety; this differs from the cis disposition found in (3). The expected easy displacement of the bound solvent molecules from the metal coordination sphere makes the three compounds good candidates for suitable starting materials in a number of synthetic applications.     

Five Coordinated Zinc(II) and Tris‐Chelate Cadmium(II) Complexes with 2,2′‐Diamino‐5,5′‐dimethyl‐4,4′‐bithiazole – Syntheses,Spectroscopic Characterization,and Crystal Structure

The new synthesized ligand (DADMBTZ = 2,2′‐diamino‐5,5′‐dimethyl‐4,4′‐bithiazole), which is mentioned in this text, is used for preparing the two new complexes [Zn(DADMBTZ)₃](ClO₄)₂. 0.8MeOH.0.2H₂O ( 1 ) and [Cd(DADMBTZ)₃](ClO₄)₂ ( 2 ). The characterization was done by IR, ¹H, ¹³C NMR spectroscopy, elemental analysis and single crystal X‐ray determination. In reaction with DADMBTZ, zinc(II) and cadmium(II) show different characterization. In 2 , to form a tris‐chelate complex with nearly C₃ symmetry for coordination polyhedron, DADMBTZ acts as a bidentate ligand. In 1 , this difference maybe relevant to small radii of Zn²⁺ which make one of the DADMBTZ ligands act as a monodentate ligand to form the five coordinated Zn²⁺ complex. In both 1 and 2 complexes the anions are symmetrically different. 1 and 2 complexes form 2‐D and 3‐D networks via N‐H···O and N‐H···N hydrogen bonds, respectively.     

Crystal Structure,Thermal Decomposition Behaviors and Sensitivity Properties of a Novel Energetic Compound [Co(DAT)6](ClO4)2

A novel energetic coordination compound [Co(DAT)₆](ClO₄)₂ has been synthesized by using 1,5‐diaminotetrazole (DAT) as a ligand and its structure has been characterized using X‐ray single crystal diffraction, elemental analysis and FT‐IR spectroscopy. The central cobalt(II) cation is coordinated by six N atoms from six DAT molecules to form a six‐coordinated and distorted octahedral structure. Di‐dimension layer structure was formed by the extensive intermolecular hydrogen bonds between DAT ligands and ClO^?₄ anions along a‐axis and b‐axis. Thermal decomposition mechanism of [Co(DAT)₆](ClO₄)₂ was investigated based on differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared (FT‐IR) spectra. The kinetic parameters of the first exothermic process were studied by applying the Kissinger's and Ozawa‐Doyle's methods. Additionally, the sensitivities of this complex were tested. The results of all the studies show that [Co(DAT)₆](ClO₄)₂ has an extreme potential application as an energetic material.     

Synthesis,Crystal Structures and Properties of Tetrametallic Complexes: [M2(phen)4(FCA)2](ClO4)2·(H2O)2 (M=Zn or Co,phen=1,10‐phenanthroline,FCA=anion of 3‐ferrocenyl‐2‐crotonic acid)

Two new complexes [Zn₂(phen)₄(FCA)₂](ClO₄)₂·(H₂O)₂ ( 1 ) and [Co₂(phen)₄ (FCA)₂](ClO₄)₂·(H₂O)₂ (2) (FCA=anion of 3‐ferrocenyl‐2‐crotonic acid, phen=1,10‐phenanthroline) have been synthesized, and characterized by elemental analysis, IR, UV‐Vis spectra, thermal analyses, and single‐crystal X‐ray diffraction. Two M(II) (M=Zn or Co) ions are bridged by two FCA anions with syn‐anti bridging ligands, leading to dimeric cores, [M₂(phen)₄(FCA)₂]²⁺, and each M(II) ion is six‐coordinated in a distorted octahedral geometry by two chelate phen ligands and two μ₂‐carboxylate oxygen atoms from two FCA groups. The M(II)…M(II) intradimer distances are 0.4391 and 0.4462 nm in 1 and 2 , respectively. Electrochemical properties of the complexes have been discussed.