Hydrogen-Bonded Networks Based on Cobalt(II), Nickel(II), and Zinc(II) Complexes of N,N'-Diethylurea

N,N'-diethylurea (DEU) was employed as a ligand to form the octahedral complexes [M(DEU)6]2+ (M=Co, Ni and Zn). Compounds [Co(DEU)6](BF4)2 (1), [Co(DEU)6](CIO4)2 (2), [Ni(DEU)6](CIO4)2 (3), and [Zn(DMU)6](CIO4)2 (4) have been prepared from the reactions of DEU and the appropriate hydrated metal(II) salts in EtOH in the presence of 2,2-dimethoxypropane. Crystal structure determinations demonstrate the existence of [M(DEU)6]2+ cations and CIO4− (in 2–4) or BF4− (in 1) counterions. The [M(DEU)6]2+ cations in the solid state are stabilized by a pseudochelate effect due to the existence of six strong intracationic N-H ⋯ O(DEU) hydrogen bonds. The [M(DEU)6]2+ cations and counterions self-assemble to form hydrogen-bonded 2D architectures in 2–4 that conform to the kgd (kagome dual) network, and a 3D hydrogen-bonded rtl (rutile) network in 1. The nature of the resulting supramolecular structures is influenced by the nature of the counter-ion. The complexes were also characterized by vibrational spectroscopy (IR)

A Mononuclear and a Mixed-Valence Chain Polymer Arising from Copper(II) Halide Chemistry and the Use of 2,2′-Pyridil

Reactions of 2,2′-pyridil (pyCOCOpy) with CuCl2 · 2H2O and CuBr2 in EtOH yielded the mononuclear complex [Cu(pyCOOEt)2Cl2] · H2O (1) and the one-dimensional, mixed-valence complex [Cu2ICuII(pyCOOEt)2Br4]n (2), respectively. Both complexes crystallize in the triclinic space group P 1¯. The lattice constants are a = 8.382(2), b = 9.778(2), c = 7.814(2), α = 101.17(1), β = 114.55(1), γ = 94.14(1)° for 1 and a = 8.738(1), b = 9.375(2), c = 7.966(1), α = 79.09(1), β = 64.25(1), γ = 81.78(1)° for 2. 2,2′-pyridil undergoes a metal-assisted alcoholysis and oxidation leading to decomposition and yielding the ethyl picolinate (pyCOOEt) ligand. The autoredox process associated with the reduction of copper(II) to copper(I) in the case of complex 2 is discussed in terms of the increased redox activity of the copper(II) bromide system relative to the copper(II) chloride system

A Mononuclear and a Mixed-Valence Chain Polymer Arising from Copper(II) Halide Chemistry and the Use of 2,2'-Pyridil

Reactions of 2, 2 -pyridil (pyCOCOpy) with (2) , respectively. Both complexes crystallize in the triclinic space group P 1. The lattice constants are a = 8.382(2), b = 9.778(2), c = 7.814(2), α = 101.17(1), β = 114.55(1), γ = 94.14(1) • for 1 and a = 8.738(1), b = 9.375(2), c = 7.966(1), α = 79.09(1), β = 64.25(1), γ = 81.7

A general synthetic route for the preparation of high-spin molecules: Replacement of bridging hydroxo ligands in molecular clusters by end-on azido ligands

Abstract A general method of increasing the ground-state total spin value of a polynuclear 3d-metal complex is illustrated through selected examples from cobalt(II) and nickel(II) cluster chemistry that involves the dianion of the gem-diol form of di-2-pyridyl ketone and carboxylate ions as organic ligands. The approach is based on the replacement of hydroxo bridges, that most often propagate antiferromagnetic exchange interactions, by the end-on azido ligand, which is a ferromagnetic coupler

Hydrogen-Bonded Networks Based on Cobalt(II), Nickel(II), and Zinc(II) Complexes of N,N-Diethylurea

N,N’-diethylurea (DEU) was employed as a ligand to form the octahedral complexes [M(DEU)(6)](2+) (M=Co, Ni and Zn). Compounds [Co(DEU)(6)](BF4)(2) (1), [Co(DEU)(6)](CIO4)(2) (2), [Ni(DEU)(6)](CIO4)(2) (3), and [Zn(DMU)(6)](CIO4)(2) (4) have been prepared from the reactions of DEU and the appropriate hydrated metal(II) salts in EtOH in the presence of 2,2-dimethoxypropane. Crystal structure determinations demonstrate the existence of [M(DEU) 6] 2+ cations and CIO4- (in 2-4) or BF4- (in 1) counterions. The [M(DEU)(6)](2+) cations in the solid state are stabilized by a pseudochelate effect due to the existence of six strong intracationic N-H center dot center dot center dot O-(DEU) hydrogen bonds. The [M(DEU)(6)](2+) cations and counterions self-assemble to form hydrogen-bonded 2D architectures in 2-4 that conformto the kgd (kagome dual) network, and a 3D hydrogen-bonded rtl (rutile) network in 1. The nature of the resulting supramolecular structures is influenced by the nature of the counter-ion. The complexes were also characterized by vibrational spectroscopy (IR)

Methanolysis as a route to gallium(III) clusters: Synthesis and structural characterization of a decanuclear molecular wheel

Treatment of a methanolic solution of gallium( III) nitrate with lithium hydroxide in the presence of benzilic acid resulted in the decanuclear cluster [ Ga( OMe)(2) O2CC( OH) Ph-2](10) ( 1). The metal and the organic components have assembled to form a cyclic molecule that adopts the structure of a wheel. The 10 Ga-III ions are approximately coplanar and are coordinated in a distorted octahedral manner by six oxygen atoms. The integrity of the molecular wheel is retained in solution, as evidenced by the (NMR)-N-1 spectrum of 1 in DMSO-d(6), while no signal in the Ga-71 NMR could be detected

Preparation, crystal structure and spectroscopic characterization of [Ga(OH)(SO4)(terpy)(H2O)]center dot H2O (terpy=2,2 ‘: 6 ‘,2-terpyridine): The first characterized gallium(III) sulfato complex

The reaction of Ga-2(SO4)(3).18H(2)O and excess 2,2’:6’,2”-terpyridine (terpy) in MeOH / H2O leads to [Ga(OH)(SO4)(terpy)(H2O)].H2O (1.H2O] in good yield. The structure of the complex has been determined by single-crystal X-ray crystallography. The Ga-III atom in 1.H2O is 6-coordinate and ligation is provided by one terdentate terpy molecule, one monodentate sulfate, one terminal hydroxide and one terminal H2O molecule; the coodination polyhedron about the metal is described as a distorted octahedron. There is an extensive hydrogen-bonding network in the crystal structure which generates corrugated layers parallel to bc. The new complex was characterized by IR and H-1 NMR spectroscopy. The spectroscopic data are discussed in terms of the nature of bonding

Synthetic analogue approach to metallobleomycins: syntheses, structure and properties of mononuclear and tetranuclear gallium(III) complexes of a ligand that resembles the metal-binding site of bleomycin

As part of our interest into the bioinorganic chemistry of gallium, gallium(III) complexes of the peptide ligand N-(2-(4-imidazolyl)ethyl)pyridine-2-carboxamide (pypepH(2)) resembling a fragment of the metal-binding domain of bleomycins (BLMs), have been isolated. Reaction of pypepH2 with (Et4N)[GaCl4] and Ga(acac)(3) [acac(-) is the acetylacetonate(-1) ion] affords the mononuclear complex [Ga(pypepH)(2)]Cl . 2H(2)O (1) and the tetranuclear complex [Ga-4(acac)(4)(pypeP)(4)] . 4.4H(2)O (2), respectively. Both complexes were characterized by single-crystal X-ray crystallography, IR spectroscopy and thermal decomposition data. The pypepH(-) ion in 1 behaves as a N(pyridyl), N(deprotonated amide), N(pyridine-type imidazole) chelating ligand. The doubly deprotonated pypep(2-) ion in 2 behaves as a N(pyridyl), N(deprotonated amide), N(imidazolate), N’(imidazolate) mu(2) ligand and binds to one Gain atom at its pyridyl, amide and one of the imidazolate nitrogens, and to a second metal ion at the other imidazolate nitrogen; a chelating acac- ligand completes six coordination at each Ga-III centre. The IR data are discussed in terms of the nature of bonding and known structures. The H-1 NMR spectrum of I suggests that the cation of the complex maintains its integrity in dimethylsulfoxide (DMSO) solution. Complexes 1 and 2 are the first synthetic analogues of metallobleomycins with gallium(III). (C) 2004 Elsevier Inc. All rights reserved