RESUMO
The mononuclear complex [Ni(pydc)(pydm)]·H2O, pyridine-2,6-dicarboxylato-2,6-bis(hydroxymethyl)pyridine nickel(ii) monohydrate, features a highly axially compressed pseudo-octahedral chromophore with significant rhombic contribution that is responsible for the sizable magnetic anisotropy of the Ni(ii) ion, D/hc≈-14 cm(-1). This complex displays superparamagnetic behaviour in an applied external field that culminates at BDC = 0.2 T. Two relaxation processes are evidenced; the faster can be analyzed in terms of the Orbach, direct, and Raman processes yielding U/kB = 21.2 (±1.3) K and τ0 = 3.83 (±1.21) × 10(-7) s. This is the first example of a field-induced single-molecule magnet in the class of hexacoordinate Ni(ii) complexes.
RESUMO
Complex [Co(PPh3)2Br2] possesses intermediate magnetic anisotropy, D/hc = -13 cm(-1). It displays superparamagnetic behavior either in the absence of the magnetic field or in fields of Bdc = 0.05, 0.1, 0.15, and 0.2 T. At Bdc = 0.1 T, the barrier to spin reversal U/kB = 37 K and the extrapolated relaxation time τ0 = 9.4 × 10(-11) s confirm its classification as a single-molecule magnet. At Bdc = 0.2 T, two relaxation processes are evidenced.
RESUMO
The asymmetric unit of the title compound, [Co(C(8)H(6)NO(2))(2)(H(2)O)(4)], contains one half-mol-ecule. The Co(II) atom lies on an inversion centre and is coordinated by two N atoms of the pyridine rings of 3-(3-pyrid-yl)acrylate anions and four O atoms of water mol-ecules in a distorted octa-hedral coordination geometry. In the crystal structure, inter-molecular O-Hâ¯O hydrogen bonds link the mol-ecules, forming a three-dimensional network.
RESUMO
In the title compound, [Cu(C(2)H(2)ClO(2))(2)(C(8)H(7)NO)(2)(CH(4)O)], the Cu(2+) ion has a highly distorted square-bipyramidal (4 + 1 + 1) coordination environment and is bonded to three carboxyl-ate O atoms of two chloro-acetate anions (monodentate and asymmetrically bidentate), two pyridine N atoms of 2-methyl-furo[3,2-c]pyridine and one methanol O atom. There is an intra-molecular O-Hâ¯O hydrogen bond. Inter-molecular C-Hâ¯O hydrogen bonds result in the formation of a three-dimensional network and π-π stacking inter-actions [3.44-3.83â Å] are observed between symmetry-related rings of 2-methyl-furo[3,2-c]pyridine. Further inter-actions in the crystal structure are a short Clâ¯Cl inter-action [3.384â (2)Å] and C-Hâ¯π inter-actions between 2-methyl-furo[3,2-c]pyridine rings.
RESUMO
The crystal structure of the title compound, [Co(C(7)H(6)NO(2)S)(2)(H(2)O)(4)], is a polymorph of the structure first reported by Du, Zhao & Wang [(2004). Dalton Trans, pp. 2065-2072]. The asymmetric unit of the title compound contains one half-mol-ecule; the Co(II) atom lies on an inversion centre in a distorted octa-hedral geometry coordinated by two N atoms of the pyridine rings of the 4-pyridylthio-acetate anions and four O atoms of water mol-ecules. In the crystal structure, inter-molecular O-Hâ¯O hydrogen bonds link the mol-ecules, forming a three-dimensional network.
RESUMO
Pyridine fused with a furan ring (fupy), and its dimethyl derivative, have been used for the first time as ligands to synthesize potentially new Werner clathrates. The extended aromatic system of pyridine-like ligands influences considerably the molecular structure of prepared nickel complexes. The molecular structure of tetrakis(furo[3,2-c]pyridine)bis(isothiocyanato)nickel(II) tetrahydrofuran (THF) solvate, [Ni(NCS)(2)(C(7)H(5)NO)(4)].C(4)H(8)O or [Ni(NCS)(2)(fupy)(4)].THF, (I), reveals a 'four-blade propeller' arrangement of ligands, with the angles between the fupy planes and the basal octahedron plane spanning the range 38.7-55.3 degrees. These angles are much larger (69.9-78.8 degrees ) in the centrosymmetric complex tetrakis(2,3-dimethylfuro[3,2-c]pyridine)bis(isothiocyanato)nickel(II) 6.6-hydrate, [Ni(NCS)(2)(C(9)H(9)NO)(4)].6.6H(2)O or [Ni(NCS)(2)(Me(2)fupy)(4)].6.6H(2)O, (II), in which crystallographically imposed inversion symmetry is present.
