Complex CoCl2 Research Articles

Synthesis of 12-vertex mixed ligand closo-cobaltacarborane complexes and molecular structure of [3,3-(Ph2P(CH2)2PPh2)-3-Cl-closo-3,1,2-CoC2B9H11

A reaction of complexes CoCl2(dppe) (dppe is the 1,2-bis(diphenylphosphino)ethane) or CoCl2(dppp) (dppp is the 1,3-bis(diphenylphosphino)propane) with [K][7,8-nido-C2B9H12] upon reflux in benzene led to the mixed ligand closo-cobaltacarboranes [3,3-(Ph2P(CH2)nPPh2)-3-Cl-closo-3,1,2-CoIIIC2B9H11] (n = 2 and 3, respectively) in moderate yields (34 and 16%). The structure of the 18-electron complexes in solution and the solid state was studied by NMR and IR spectroscopy, the structure in the case of the closo-complex with dppe-ligand was confirmed by X-ray crystallography.

Peculiarities of molecular structure of 1-vinylimidazole: High resolution NMR study

The peculiarities of molecular structure of 1-vinylimidazoles were studied using 1Н and 13С NMR spectra of its complexes. Mechanisms of delocalization of unpaired electron spin density in the complex CoCl2⋅4(1-vinylimidazole) were revealed. Characteristic features of 1-vinylimidazole coordination with (C2H5)3SnCl were established. Unlike paramagnetic cobalt complex, the structure of VIM diamagnetic complex with triethylhalogenstananne R represents a trigonal bipyramid. The Sn atom in this complex has sp3d-hybridization and three alkyl moieties trend towards coplanarity interacting with sp2-orbitals of tin. The long-range spin–spin interaction between protons of 1-vinylimidazole and the vinyl group coupled with the pyrrole nitrogen N1, typical for coplanar arrangement the imidazole cycle and vinyl moiety was found.

Metallosupramolecular Chemistry of Novel Chiral closo-o-Carboranylalcohol Pyridine and Quinoline Ligands: Syntheses, Characterization, and Properties of Cobalt Complexes

The cobalt(II) complexes CoCl2(LOH)2 (LOH = 1-[R(hydroxy)methyl]-2-R′-1,2-dicarba-closo-dodecaborane (R′ = H or Me; R = 2-pyridyl 3a or 4a, 3-pyridyl 3b or 4b, 4-pyridyl 3c or 4c, 2-quinolyl 3d or 4d, 4-quinolyl 3e or 4e)) and CoCl2(LOH)4 (5, R′ = H; R = 4-pyridyl) were synthesized and characterized. Deprotonation of alcohol in 3a afforded the square-planar complex CoII(LO)2 (6) that oxidized slowly in solution and under air to give the cobaltacarborane complex CoIII{(η5-C2B9H10)(CHOH)(η1-NC5H4)}(η2-NC5H4COO) (7). Crystal structures for 3a, 3a·2MeOH, 3b, 3e, 4c, 4e, 5, 6, and 7 have been determined by X-ray diffraction (XRD). Molecular structures show octahedral (3a, 3a·2MeOH, 5), tetrahedral (3b, 3e, 4c, 4e), and square-planar (6) coordination around CoII centers, whereas 2-pyridyl and quinolyl ligands favor a bidentate N,O-coordination mode and 3- and 4-pyridyl and quinolyl ligands favor a monodentate N-coordination. The supramolecular structures are dominated by intermolecular O–H···Cl/O hydrogen bonds...

Synthesis and molecular structure of cobalt(II) complex with 1-(1-silatranylmethyl)-1,2,4-triazole

Reaction of cobalt chloride with 1-(1-silatranylmethyl)-1,2,4-triazole in benzene afforded complex CoCl2·2L (L = 1-(1-silatranylmethyl)-1,2,4-triazole). It was isolated as the solvate [CoCl2·2L]·CH2Cl2 (1) by recrystallization from dichloromethane and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P21/m with a = 6.798(2) E, b = 20.326(5) E, c = 11.005(3) E, and Z = 4. The cobalt atom is in slightly distorted square-planar environment, coordinated to two nitrogen atoms from two ligands and two chloride ions.

CoII and RhI complexes with C 2-symmetric chiral diamines of the dioxolane series

The reaction of di-μ-chlorobis(1,5-cyclooctadiene)dirhodium with (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane (1) gave the complex [Rh(cod)(1)]Cl (cod is 1,5-cyclooctadiene). The composition of the complexes CoCl2 · L2 and [Rh(cod)(L2)]X (L2 = 1, (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane; X = Cl, TfO) was studied using IR and 1H NMR spectroscopy. In the RhI cyclooctadienediamine complexes, the diene molecule forms a stronger bond with the metal atom than that in the cyclooctadienediphosphine analogs.

Borohydride reduction of acetophenone and esters of dehydrocarboxylic acids in the presence of chiral cobalt(II) diamine complexes

The catalytic reduction of acetophenone, methyl α-acetamidocinnamate, and dimethyl itaconate with alcohol-modified sodium borohydride was studied in the presence of complexes CoCl2·L2 (L2 are chiral C2-symmetric diamines: (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(diphenylaminomethyl)-1,3-dioxolane). The maximum enantiomeric excess of (S)-1-phenylethanol was 24%, that of dimethyl α-methylsuccinate was 38%.

Synthesis and X-ray Structure of CoCl2(PiPrPh2)2. A New Highly Active and Stereospecific Catalyst for 1,2 Polymerization of Conjugated Dienes When Used in Association with MAO

The new cobalt (II) phosphine complex CoCl2(PiPrPh2)2 was synthesized by reacting CoCl2 with isopropyldiphenylphosphine in ethyl alcohol as solvent. The molecular structure of the complex was determined by the X-ray diffraction method. CoCl2(PiPrPh2)2 was then used in combination with methylaluminoxane for the polymerization of 1,3-butadiene: it was found to be highly active and stereospecific for the preparation of 1,2 syndiotactic polybutadiene. The same system was also able to polymerize substituted butadienes giving highly stereoregular 1,2 polymers from E-1,3-pentadiene, 1,3-hexadiene, and 3-methyl-1,3-pentadiene. Some of these polymers are completely new and were never prepared before.

Synthesis, structures and thermal properties of three crystalline polymorphs of the bis(n-phenylmethylbenzimidazole-n) dichloro cobalt(II) complex CoCl2(C7H5N2CH2Ph)2

Three polymorphic, crystalline specimens of the bis(N-phenylmethylbenzimidazole-N)dichloro cobalt(II) complex CoCl2(C7H5N2CH2Ph)2 have been obtained from different solvents and their structures determined by X-ray diffraction. X-ray analysis revealed that the three compounds have the same composition; however, details of their molecular structure differ significantly. The α-form is triclinic, space group , with lattice parameters a = 10.396(2), b = 10.439(2), c = 13.665(3) Å, α = 90.13(3), β = 110.15(3), γ = 110.46(3)°; both the β- and γ-forms crystallize in the monoclinic space group P21/c, with lattice parameters a = 12.884(3), b = 9.612(2), c = 21.761(7) Å, β = 108.02(3)° for the β-form and a = 7.357(2), b = 18.337(4), c = 19.572(5) Å, β = 107.46(3)° for the γ-form. In all three cases, the asymmetric unit consists of [CoCl2(C7H5N2CH2Ph)2] molecules. The geometry of their CoCl2N2 chromophore is a distorted tetrahedron. Thermogravimetric analysis (TGA) indicates that they have different thermal stabilities and give rise to different resting residues. The electronic and IR spectra were also investigated. Analysis of the extent to which the stereochemistry of the constituent molecules in polymorphs A, B and C differ was examined using the program MATCHIT. There are major differences in the atomic positions of chemically related atoms that are not related to space group differences. The differences are caused by significant torsional motions of the flexible groups that seem to be caused by changes in the solvent media from which the crystals were obtained. Thus, the solvent cage of the parent solutions seems to be, at least partially, responsible for the incidence of crystalline polymorphism.

First Sphere Coordination Chemistry of Modified Cyclodextrins: TheBis-CoCl2andBis-CuBr2Complexes of 6A,6B,6D,6E-Tetra-O-Nicotinoyl-α-Cyclodextrin

Abstract Substitution of the primary hydroxyl groups of α-cyclodextrin by nicotinate groups in an ABDE conformation yields a molecule having two pairs of pyridyl ligands. The compound complexes CoCl2 and CuBr2 in methanol or acetone to yield 1:2 complexes which are soluble in chloroform. The electronic spectrum of the blue CoCl2 complex is almost identical to that of Co(Py)2Cl2, implying a molecular complex with a tetrahedral geometry. The molecular graphics study of this complex shows the two CoCl2 groups positioned over and outside of the rim of unoccupied α-cyclodextrin.

Synthesis and Characterization of Dipyrazolylalkanes, and Some of Their Complexes With CoCl2

The reaction of dipyrazol-1-yl ketone with appropriate ketonic compounds is catalyzed by the presence of CoCl2, to yield dipyrazolylalkanes (C3H3N2)2CRR′, (a) where R = R′ = CH3, CD3, C2H5; (b) where R = H, R′ = CH3, C6H5; (c) where R = CH3, R′ = C2H5; and 1,1-dipyrazolylcycloalkanes derived from cyclobutanone, pentanone, hexanone, 3-methyl and 4-methylhexanone. Cobalt(II) chloride reacts with dipyrazol-1-yl ketone, in tetrahydrofuran, to yield the complex CoCl2(C3H3N2)2CO, and in acetone or acetone-d6 to yield CoCl2(C3H3N2)2C(CH3)2 or CoCl2(C3H3N2)2C(CD3)2.

Complexes of Bi- and ter-valent nickel with olefinic ditertiary arsines

Cobalt(II) salts react with 1,2-bis(dimethylarsino)ethylene (edas)(ca. 90%trans, 10%cis) under u.v. irradiation to give complexes of cis-edas in good yield. The intermediate complexes of trans-edas are generally unstable, but a black compound Col2(trans-edas)2 with one unpaired electron can be isolated; this probably contains bridging ligand groups in a polymeric structure. The cobalt(II) complexes CoX2(cis-edas)2(X = Cl, Br, I, or NO3), which have one unpaired electron, are probably five-co-ordinate in solution and tetragonally distorted octahedral in the solid state. The complex CoCl2(cis-edas) appears to consist of the planar cation [Co(cis-edas)2]2+ and the tetrahedral anion [CoCl4]2– in the solid state, but attempts to prepare [Co(cis-edas)3]2+ give only the tervalent derivative [Co(cis-edas)3]3+. The cobalt(II) halogeno-complexes of cis-edas are readily oxidised to cobalt(III) complexes of the type [CoX2(cis-edas)2]Y [X = Cl or Br; Y = Cl, Br, or PF6; X = NCS, Y = PF6 or Co(SCN)4] The chemical and physical properties of the cobalt–cis-edas complexes are generally very like those of the analogous complexes of o-phenylenebis(dimethylarsine).