Aluminum halide-cobalt halide polynuclear complexes active in low-temperature conversion of alkanes: Formation, molecular structures, and IR spectra

Shilina,Bakharev,Smirnov

, p. 2251 - 2260 (2008)

Low-temperature FT-IR studies of products of co-condensation of aluminum chloride and cobalt chloride in hydrocarbon matrices were carried out in the temperature range 80-250 K. DFT quantum mechanical calculations of the geometry and vibrational frequenci

Allan, J. R.,Paton, A. D.,Turvey, K.,Gerrard, D. L.,Hoey, S.

, p. 291 - 300 (1989)

New complexes of 4-[(4-fluorophenyl)amino]-4-oxobut-2-enoic acid with selected transition metal ions: Synthesis, thermal, and magnetic properties

Ferenc,Sadowski,Tarasiuk,Cristóv?o,Osypiuk,Sarzyński

, p. 2719 - 2727 (2017)

Complexes of 4-[(4-fluorophenyl)amino]-4-oxobut-2-enoic acid, HL, with Mn(II), Co(II), Ni(II), Cu(II), Nd(III), Gd(III), and Er(III) were synthesized and characterized by various physico-chemical methods: elemental analysis, FT-IR, TG, DTG, DSC, TG/FT-IR, XRF, XRD, and magnetic measurements using the Gouy’s method and a SQUID-VSM magnetometer. The complexes were found to be hydrates (except Er(III) complex) containing 1 to 4 molecules of water. The carboxylate groups acted as bidentate ligands.

Mixed-Ligand Cobalt(III) Complexes of a Naturally Occurring Coumarin and Phenanthroline Bases as Mitochondria-Targeted Dual-Purpose Photochemotherapeutics

Hussain, Akhtar,Kumar, Arun,Sahoo, Somarupa,Sarkar, Tukki

, p. 6649 - 6662 (2021)

The bioessential nature of cobalt and the rich photochemistry of its coordination complexes can be exploited to develop potential next-generation photochemotherapeutics. A series of six novel mixed-ligand cobalt(III) complexes of the formulation [Co(B)2(L)]ClO4 (1-6), where B is an N,N-donor phenanthroline base, namely, 1,10-phenanthroline (phen in 1 and 4), dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq in 2 and 5), and dipyrido[3,2-a:2′,3′-c]phenazine (dppz in 3 and 6), and L is an O,O-donor dianionic ligand derived from catechol (1,2-dihydroxybenzene, cat2-, in 1-3) or esculetin (6,7-dihydoxycoumarin, esc2-, in 4-6), have been prepared and characterized, and their light-triggered cytotoxicity has been studied in cancer cells. The single-crystal X-ray diffraction structures of complexes 1 (as PF6- salt, 1a) and 2 show distorted octahedral geometries around the cobalt(III) center formed by the set of N4O2 donor atoms. The low-spin and 1:1 electrolytic complexes 1-6 display a d-d transition around 700 nm. Complexes 4-6 with a coordinated esc2- ligand additionally display a π→ π? intraligand transition centered at 403 nm. Complexes 4-6 possessing a naturally occurring and photoactive esc2- ligand show high visible-light-triggered cytotoxicity against HeLa and MCF-7 cancer cells, yielding remarkably low micromolar IC50 values while being much less toxic under dark conditions. Control complexes 1-3 possessing the photoinactive cat2- ligand show significantly less cytotoxicity either in the presence of light or in the dark. The complex-induced cell death is apoptotic in nature caused by the formation of reactive oxygen species via a type 1 photoredox pathway. Fluorescence microscopy of HeLa cells treated with complex 6 reveals mitochondrial localization of the complex. A significant decrease in the dark toxicity of free esculetin and dppz base is observed upon coordination to cobalt(III). Complexes bind to calf-thymus DNA with significant affinity, but 6 binds with the greatest affinity. Complex 6 efficiently photocleaves supercoiled DNA to its nicked circular form when irradiated with visible light via a photoredox type 1 pathway involving hydroxyl radicals (HO?). Thus, complex 6 showing remarkable visible-light-triggered cytotoxicity but negligible toxicity in the dark is a good candidate for cancer photochemotherapy applications.

Synthesis, molecular, and crystal structures of 3d transition metal cyanocyclopentadienides [M(MeOH)n(H2O)4-n{C5(CN)4X}2] (M=Mn, Fe, Co, Ni, Cu, Zn; X=H, CN, NH2, NO

Sünkel, Karlheinz,Reimann, Dietmar,Nimax, Patrick

, p. 109 - 118 (2019)

The reaction of the 3d transition metal dichlorides MCl2 (M=Mn, Fe, Co, Ni, Cu, Zn) with the silver salts of substituted tetracyanocyclopentadienides Ag+ [C5(CN)4X]- (X=CN, H, NH2 NO2

Jasim, Fahdil,Hamid, Khalida

, p. 189 - 194 (1989)

Molecular complexes of cobalt(II) and Zinc(II) chlorides and bromides with 1-piperidinyl dimethylcarbamodithioate (L): Crystal structures of L and [ZnLBr2]

Seifullina,Khitrich,Vologzhanina

, p. 184 - 189 (2011)

Complexes of MX2(M = Co, Zn; X = Cl, Br) with 1-piperidinyl dimethylcarbamodithioate (L) of composition [MLX2] have been synthesized. The compounds have been studied by elemental analysis; X-ray diffraction; thermogravimetry; conductometry; magnetochemistry; and IR, 1H NMR, and electronic absorption spectroscopy. The ligand molecule is coordinated to the metal atoms in a bidentate chelating mode through the thione sulfur atom and the sulfenamide nitrogen atom to form a five-membered chelate ring. The structures of L and [ZnLBr2] have been determined by X-ray crystallography.

Synthesis, Reactions, Spectral (IR and Visible) and Magnetic Studies of Bimetallic Alkoxides Containing Co(μ-OR)3M (M=Nb or Ta) Bridging Units

Dubey, Raj Kumar,Singh, Anirudh,Mehrotra, Ram Charan

, p. 983 - 988 (1988)

Interactions of CoCl2 with Ki)6> in 1:2 molar ratio in PriOH and C6H6 result in products with the composition i)6>b42> (M=Nb or Ta) in quantitative yields.Interchange reactions of these isopropoxi

Ingier-Stocka, E.

, p. 107 - 120 (1990)

Li-Min, Zheng,Wei-Hua, Zhang,Xin-Quan, Xin

, p. 273 - 278 (1993)

-

Tewksbury,Haendler

, p. 2336 (1949)

-

Synthesis, characterization and thermal behavior of cobalt(II) 5-chloro-piridylamides complexes

Lima, Cicero B.A.,Espínola, José G.P.,De Oliveira, Severino F.,Arakaki, Luiza N.H.,Fonseca, Maria G.,Airoldi, Claudio

, p. 117 - 120 (2003)

Purple cobalt(II) complexes containing 5-chloro-2-aminepyridylacetamide (CPA), 5-chloro-2-aminepyridylpropionamide (CPP) and 5-chloro-2-aminepyridylbutyramide (CPB) ligands were prepared from ethanolic solutions. The general stoichiometry CoL2Cl2 (L = ligand) was determined from elemental analysis data. Infrared results show monodentate CPA and CPP ligands through the aromatic nitrogen atom, CPB is bidentate through the aromatic nitrogen atom and carboxyl group. Thermogravimetric curves under nitrogen showed in the final stage all complexes presented a mixture of cobalt(II) chloride and metallic cobalt as residue. The complexes containing CPA and CPP ligands decomposed in various stages with integral loss of ligand or partial loss of the chloride. Only two steps of decomposition are seen for CPB compound.

Partington, J. R.,Towndrow, R. P.

, p. 156 - 156 (1937)

Rasines, I.,Setien, J. I. Morales de

, p. 239 - 246 (1980)

House, J. E. Jr.,Kemper, K. A.,Fogel, H. M.

, p. 263 - 268 (1988)

Catalytic electroreduction of oxygen on products of pyrolysis of heterobimetallic complexes of zinc

Pirskii,Kublanovskii,Shevchenko,Kokozei

, p. 1964 - 1968 (2006)

Electrocatalysts for reduction of oxygen were synthesized from AG-3 activated carbon promoted with pyrolized heterobimetallic complexes [CoLCl 2] [ZnDMFACl3] and [ML][ZnCl4] (M = Cu 2+, Ni2+; L = 4,6,

Fogel, H. M.,House, J. E., Jr.

, p. 231 - 238 (1988)

Cryosynthesis, structure, and spectroscopic properties of aluminum chloride-cobalt(II) chloride complexes: Experiment and calculations

Shilina,Bakharev,Kuramshina,Smirnov

, p. 297 - 305 (2004)

Products of co-condensation of aluminum chloride and cobalt(II) chloride vapors were studied by low-temperature (80-200 K) IR spectroscopy. In addition to 2:1 complexes, previously unknown equimolar associates were found and their IR spectra were investigated. Quantum-mechanical calculations were carried out including electron correlation with the use of the B3LYP and PBE density functionals. The geometric structures were optimized and harmonic vibrational frequencies of the molecules of aluminum chloride, cobalt chloride, and their complexes with different compositions were calculated. Under conditions of limited molecular mobility, the (AlCl3)2·CoCl 2 complexes can be stabilized in structures containing the Co atom in a tetrahedral or distorted octahedral environment. Their thermal stability limits were determined. It was found that labile ionic species are generated in the reactions of aluminum chloride complexes with cobalt chloride with different compositions at 120-170 K.

Thermal decomposition studies on cobalt(II) complexes of 4-N-(4′-antipyrylmethylidene)aminoantipyrine with varying counter ions

Madhu,Radhakrishnan,Williams, Edna,Linert

, p. 157 - 161 (2005)

The phenomenological, kinetic and mechanistic aspects of the nitrate, chloride, bromide and iodide complexes of cobalt(II) with 4-N-(4′- antipyrylmethylidene)aminoantipyrine (AA) have been studied by TG and DTG techniques. The kinetic parameters such as a

Vitulli, G.,Porri, L.,Segre, A. L.

, (1971)

Ingier-Stocka, E.,Bogacz, A.

, p. 1373 - 1386 (1989)

Thermal and structural studies of amide complexes of transition metal(II) chlorides. I: Stoichiometry

Nelwamondo, Aubrey N.,Eve, Desmond J.,Watkins, Gareth M.,Brown, Michael E.

, p. 165 - 175 (1998)

A series of aliphatic amide complexes of nickel(II), cobalt(II) and copper(II) chlorides has been prepared. These complexes have the general formulae: NiL2Cl2·2H2O, NiL2Cl2, Ni3L2Cl6, Ni3LCl6, CoL2Cl2 and CuL2Cl2, where L is the amide ligand. Ligands ranging from formamide to butyramide, both with and without N-methyl and N-ethyl substituents, were used. The complexes were found, from the absorption spectra, to be octahedral or distorted-octahedral, except for some of the cobalt complexes with dimethyl substituted ligands which are tetrahedral. Infrared spectra confirm that coordination to the metal ion is through the carbonyl oxygen. The effects of the structure and the nature of the different amide ligands on the thermal stabilities of the complexes have been investigated by thermal analysis. As indicators of the stability of the metal-amide binding, thermal decomposition onset temperatures (Te), peak temperatures (Tmax) and enthalpies (ΔHL) were compared for complexes with similar composition, geometrical structure and decomposition stoichiometry. Results do not support the enhancement of thermal quantities with increasing basicity of the amides. Instead, steric factors appear to play a more important role in determining the magnitudes of ΔHL, Te and Tmax.

Thermochemistry of the complexes of some microelements and histidine

Chen,Gao,Yang,Hu,Shi

, p. 967 - 975 (2003)

Solid complexes of M(His)2Cl2·nH2O (M=Mn, Co, Ni, Cu) of MnCl2·6H2O, CoCl 2·6H2O, NiCl2·6H2O, CuCl2·2H2O and L-α-histidine (His) have been prepared in 95% ethanol solution and characterized by elemental analyses, chemical analyses, IR and TG-DTG. The constant-volume combustion energies of the complexes have been determined by a rotating-bomb calorimeter. The standard enthalpies of formation of the complexes have been calculated as well.

Wolford, Thomas L.,Musker, W. Kenneth

, p. 19 - 24 (1991)

Weiss,Huebel

, p. 42,44, 50 (1959)

Bis(dinitrogen)cobalt(-1) Complexes with NHC Ligation: Synthesis, Characterization, and Their Dinitrogen Functionalization Reactions Affording Side-on Bound Diazene Complexes

Gao, Yafei,Li, Guangyu,Deng, Liang

, p. 2239 - 2250 (2018/02/19)

Late-transition-metal-based catalysts are widely used in N2 fixation reactions, but the reactivity of late-transition-metal N2 complexes, besides iron N2 complexes, has remained poorly understood as their N2 complexes were thought to be labile and hard to functionalize. By employing a monodentate N-heterocyclic carbene (NHC), 1,3-dicyclohexylimidazol-2-ylidene (ICy) as ligand, the cobalt(0)- and cobalt(-1)-N2 complexes, [(ICy)3Co(N2)] (1) and [(ICy)2Co(N2)2M]n (M = K, 2a; Rb, 2b; Cs, 2c), respectively, were synthesized from the stepwise reduction of (ICy)3CoCl by the corresponding alkaline metals under a N2 atmosphere. Complexes 2a-c in their solid states adopt polymeric structures. The N-N distances (1.145(6)-1.162(5) ?) and small N-N infrared stretchings (ca. 1800 and 1900 cm-1) suggest the strong N2 activation of the end-on N2 ligands in 2a-c. One electron oxidation of 1 by [Cp2Fe][BF4] gave the cobalt(I) complex devoid of N2 ligand [(ICy)3Co][BF4] (3). The bis(dinitrogen)cobalt(-1) complexes 2a-c undergo protonation reaction with triflic acid to give N2H4 in 24-30% yields (relative to cobalt). Complexes 2a-c could also react with silyl halides to afford diazene complexes [(ICy)2Co(η2-R3SiNNSiR3)] (R = Me, 6a; Et, 6b) that are the first diazene complexes of late transition metals prepared from N2 functionalization. Characterization data, in combination with calculation results, suggest the electronic structures of the diazene complexes as low-spin cobalt(II) complexes containing dianionic ligand [η2-R3SiNNSiR3]2-. Complexes 1, 2a-c, 6a, 6b, and (ICy)2CoCl2 proved to be effective catalysts for the reductive silylation of N2 to afford N(SiMe3)3. These NHC-cobalt catalysts display comparable turnover numbers (ca. 120) that exceed the reported 3d metal catalysts. The fine performance of the NHC-cobalt complexes in the stoichiometric and catalytic N2-functionalization reactions points out the utility of low-valent low-coordinate group 9 metal species for N2 fixation.