Average Ni-N Bond Length Research Articles

Crystal structure of trans-di-aqua-(1,4,8,11-tetra-aza-undeca-ne)nickel(II) bis-(pyridine-2,6-di-carboxyl-ato)nickel(II).

The asymmetric unit of the title compound, trans-di-aqua-(1,4,8,11-tetra-aza-undecane-κ4 N 1,N 4,N 8,N 11)nickel(II) bis-(pyridine-2,6-di-carboxyl-ato-κ3 O 2,N,O 6)nickel(II) {[Ni(L)(H2O)2][Ni(pdc)2] where L = 1,4,8,11-tetra-aza-undecane (C7H20N4) and pdc = the dianion of pyridine-2,6-di-carb-oxy-lic acid (C7H3NO4 2-)} consists of an [Ni(L)(H2O)2]2+ complex cation and a [Ni(pdc)2]2- anion. The metal ion in the cation is coordinated by the four N atoms of the tetra-amine ligand and the mutually trans O atoms of the water mol-ecules in a tetra-gonally elongated octa-hedral geometry with the average equatorial Ni-N bond length slightly shorter than the average axial Ni-O bond [2.087 (4) versus 2.128 (4) Å]. The ligand L adopts its energetically favored conformation with five-membered and six-membered chelate rings in gauche and chair conformations, respectively. In the complex anion, the NiII ion is coordinated by the two tridentate pdc2- ligands via their carboxyl-ate and nitro-gen atom donors in a distorted octa-hedral trans-NiO4N2 geometry with nearly orthogonal orientation of the planes defining the carboxyl-ate rings and the average Ni-N bond length [1.965 (4) Å] shorter than the average Ni-O bond distance [2.113 (7) Å]. In the crystal, the NH donor groups of the tetra-amine, the carb-oxy-lic groups of the pdc2- anion and the coordinated water mol-ecules are involved in numerous N-H⋯O and O-H⋯O hydrogen bonds, leading to electroneutral sheets oriented parallel to the (001) plane.

Crystal structure of [5-n-butyl-10-(2,5-di-meth-oxy-phen-yl)-2,3,7,8,13,12,17,18-octa-ethyl-porphyrin-ato]nickel(II).

The asymmetric unit of the title nickel(II) porphyrin, [Ni(C48H60N4O2)], contains one independent mol-ecule. The average Ni-N bond length is 1.917 (13) Å. The mol-ecules are arranged in a closely spaced lattice structure in which neighbouring porphyrins are oriented in inversion-related dimers. The nickel(II) porphyrin is characterized by a significant degree of a ruffled (B 1u ) conformation with small contributions from saddle (B 2u ) and wave (y) [Eg (y)], as determined using normal structural decomposition. Disorder in the 2,5-di--meth-oxy-phenyl substituent was modelled over two positions with a 60% occupancy for the major moiety. One of the ethyl groups is also disordered over two positions and was modelled with the major moiety being present in 51.3% occupancy.

{rac-5-[Methoxy(phenyl)methyl]-10,20-diphenylporphyrinato}nickel(II)

The title compound, [Ni(C40H28N4O)], was obtained from a Grignard reaction of the respective formyl­porphyrin to yield {5-[hy­droxy(phen­yl)meth­yl]-10,20-diphenyl­porphyrinato}nickel(II), followed by crystallization from methyl­ene chloride/methanol. The mol­ecule exhibits a ruffled macrocycle with an average deviation of the 24 macrocycle atoms from their least-squares plane (Δ24) of 0.26 Å and an average Ni—N bond length of 1.931 (2) Å. In line with the asymmetrical substituent pattern, the degree of distortion is slightly larger at point of attachment of the meth­oxy(phen­yl)methyl residue than at the unsubstituted meso position. The meth­oxy group attached to the chiral C atom is disordered in a 0.534 (4):0.466 (4) ratio.

(5,15-Dianthracen-9-yl-10,20-dihexylporphyrinato)nickel(II): a planar nickel(II) porphyrin

The title compound, [Ni(C60H52N4)], is an example of a meso tetra­substituted nickel(II) porphyrin with both meso aryl and alkyl residues. The mol­ecule exhibits a planar macrocycle with an average deviation of the 24 macrocycle atoms from their least-squares plane (Δ24) of 0.01 Å and an average Ni—N bond length of 1.960 (2) Å. The NiII atom lies on a center of inversion. The structure presents a rare example for a planar nickel(II) porphyrin, as meso-substituted nickel(II) porphyrins with either only meso-aryl or with meso-alkyl residues typically exhibit a ruffled conformation.

Iron(II) and Nickel(II) Complexes of 4,4′-Bithiazole: Spectral, Magnetic and Structural Studies

Iron(II) and nickel(II) complexes of 4,4′-bithiazole (L) have been prepared. Salts of [FeL3]2+ undergo thermally induced spin-state transitions, in the solid state and in solution. The structures of both [FeL3] [ClO4]2 and [NiL3] [ClO4]2 have been determined by single-crystal X-ray diffractometry . The compounds are isomorphous : monoclinic with space group C2/c, with four molecules in a unit cell of dimensions (Fe, Ni): a 17.250(3), 17.379(3); b 9.8168(9), 9.685(1); c 16.867(3), 17.135(3) Ǻ; β 105.943(7), 104.860(7)°. The structures were refined by least-squares methods to residuals of 0.033 (Fe) and 0.033 (Ni) for 1917 (Fe) and 2017 (Ni) observed reflections. The cations have a distorted octahedral structure with the average Ni-N bond length being 0.11 Ǻ longer than the average Fe-N bond length.