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N Bond Lengths (n + bond_length)
Selected AbstractsAnomeric effect for a 2,5,7-triazabicyclo[2.2.1]heptane derivativeACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2009Amir Taheri A new member of the polyazapolycyclic family of compounds, namely N3,N6,2,5,7-pentaphenyl-2,5,7-triazabicyclo[2.2.1]heptane-3,6-diamine xylene solvate, C34H31N5·C8H10, was synthesized for the first time and the crystal structure is reported. There are no hydrogen bonds joining the molecules. All four chiral C atoms have the same absolute configurations. With regard to the four N,C,N groups, anomeric effects are observed to cause a reduction of C,N bond length and N-atom pyramidality. [source] Isoamylcobalamin,acetone,water (1/0.385/12.650)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2004Christopher B. Perry The title compound, [Co(C5H11)(C62H88N13O14P)]·0.385C3H6O·12.650H2O, contains the isoamyl (3-methylbutyl) anion bonded to the CoIII ion through a C atom. The compound is thus a structural analog of the two biologically important vitamin B12 coenzymes adenosylcobalamin and methylcobalamin. The lower axial Co,N bond length [2.277,(2),Å] is one of the longest ever reported for a cobalamin and reflects the strong ,-donor ability of the isoamyl group. [source] Configuration of Octahedral Metal Compounds , Equilibrium, Crystal and Molecular Structure of Nickel(II) Complexes of Linear N2O4, N4S2 or N6 Donors Set Atoms LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2004Aminou Mohamadou Abstract Two new nickel(II) complexes of symmetric hexadentate mixed-ligand N,O [1,12-bis(2-pyridyl)-5,8-dioxa-2,11-diazadodecane (pydado)] and N,S [1,12-bis(2-pyridyl)-5,8-dithia-2,11-diazadodecane (pydadt)] donor atoms have been synthesised as perchlorate salts and characterised by X-ray crystallography and ligand-field spectroscopy. In both complexes the Ni2+ ion is hexacoordinate. The cation [Ni(pydado)]2+ is pseudo-octahedral with the two pyridyl groups in trans position; all Ni,N and Ni,O bond lengths are practically equivalent. In [Ni(pydadt)]2+ complex, however, the size of the thioether sulfur atoms imposes a C2v symmetry; the pyridyl groups and the sulfur atoms are in trans positions and all Ni,N bond lengths are equivalent. The comparison of these structures with those of octahedral cobalt, copper and zinc complexes with the same ligands shows that their configurations depend not only on the nature of the two central donor atoms of the ligand, but also on the nature of the metallic ion. In aqueous solution, the stability constants of the NiII chelates with these two ligands, determined by potentiometry, show the formation of [Ni(LH)]3+ and [NiL]2+ species in all cases. The chelating power of the pydadt ligand is slightly greater than that of pydado. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] On the precision and accuracy of structural analysis of light-induced metastable statesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2007Vincent Legrand Bragg diffraction data were collected on single crystals of the spin-crossover complex [Fe(phen)2(NCS)2] in its low-spin and light-induced metastable high-spin states. Experimental variables included the temperature (32 and 15,K), the X-ray source (sealed tube and synchrotron), and the time interval between laser light excitation of the sample (, = 647,nm). From a comparison of the structural parameters refined, it is shown that photo-crystallographic measurements suffer significantly and systematically from bias if the probed sample contains residual ground-state species, resulting from an incomplete photo-conversion or a significant metastable- to ground-state relaxation. It follows that a 4% population of species in a different spin state affects the Fe,N bond lengths by more than three standard deviations, and the FeN6 polyhedron volume by as much as seven standard deviations, while the mean atomic position misfit exceeds 0.005,Å. [source] Structural investigations of phosphorus,nitrogen compounds.ACTA CRYSTALLOGRAPHICA SECTION B, Issue 3-2 2002A systematic study is presented on the products of aminolysis of N3P3Cl6 (1) and N3P3Ph2Cl4 (4) with dibenzylamine. Two series of mono- and disubstituted derivatives of compounds (1) and (4), namely N3P3Cl5[N(CH2Ph)2] (2) and N3P3Cl4[N(CH2Ph)2]2 (3) and N3P3Ph2Cl3[N(CH2Ph)2] (5) and N3P3Ph2Cl2[N(CH2Ph)2]2 (6) [where (2), (3), (5) and (6) are new structures], are investigated in order to determine whether steric or electronic effects prevail in the formation of dibenzylamino-substituted cyclophosphazenes. The influence of an electron-releasing group (i.e. phenyl) on the stereochemistry and degree of substitution of the product is analysed by comparison of the above two series. The difference in unsymmetrically substituted endocyclic P,N bond lengths, ,, is used as a measure of the degree of the electronic contribution, in combination with basicity constants, to quantify the degree of the electron-releasing capacity of the R group. In order to compare geminal versus non-geminal substitution, a difunctional secondary amine was used to form the compound N3P3Cl4[NMe(CH2)3NMe] (7) (a reinvestigation) for inclusion in this study. It is shown that electron-releasing groups have a greater effect on the lengthening of P,Cl bonds as opposed to endocyclic P,N bonds and that this effect is greater in the non-geminal PRCl case than for geminal PCl2. However, steric effects are shown to be dominant in the reactions of dibenzylamine with N3P3 derivatives, with a disposition to a trans stereochemistry in bisdibenzylamino derivatives. [source] Diaquatetrakis(tert -butyl isocyanide)cobalt(II) bis(perchlorate): an example of cobalt(II) coordinated by only four alkyl isocyanide ligandsACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Clifford A. L. Becker The title compound, [Co(C5H9N)4(H2O)2](ClO4)2, crystallizes in the monoclinic space group C2/m. The cation has space-group-imposed 2/m symmetry, while the perchlorate ion is disordered about a mirror plane. The two slightly non-equivalent Co,C bonds [1.900,(3) and 1.911,(3),Å] form a rectangular plane, with a C,Co,C bond angle of 86.83,(11)°, and the linear O,Co,O C2 axis is perpendicular to this plane. The C[triple-bond]N bond lengths are 1.141,(4),Å and the Co,C[triple-bond]N and C[triple-bond]N,C angles average 175.5,(4)°. The perchlorate counter-ions are hydrogen bonded to the water molecules. The title compound is the first example of four alkyl isocyanide ligands coordinating CoII upon initial reaction of Co(ClO4)2·6H2O/EtOH with alkyl isocyanide. In all other known examples, five alkyl isocyanide molecules are coordinated, as in [(RNC)5Co,Co(CNR)5](ClO4)4 (R = Me, Et, CHMe2, CH2Ph, C4H9 - n or C6H11) or [Co(CNC8H17 - t)5](ClO4)2. This complex, therefore, is unique and somewhat unexpected. [source] Bis[S -6-(2,2:6,,2,,-terpyridin-4,-yloxy)hexyl thioacetate]manganese(II) bis(hexafluorophosphate)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Kasper Moth-Poulsen The structure of a manganese(II) complex of terpyridine functionalized with acetylsulfanyl-terminated hexyloxy chains, [Mn(C23H25N3O2S)2](PF6)2, is described. This type of complex is of interest in the study of single-molecule transport properties in open-shell systems. The manganese coordination environment is distorted octahedral but, importantly, with no larger deviations from the idealized geometry than those observed for other metal,terpyridine complexes. The Mn,N bond lengths range from 2.192,(2) to 2.272,(3),Å. The title compound crystallizes with the cation and anions all on general positions, with the hexafluorophosphate anions exhibiting orientational disorder. When compared with other bis-terpyridine complexes, this structure demonstrates that manganese(II) is no more prone to undergo low-symmetry distortions than systems with ligand field stabilization energy contributions. [source] The zwitterion of 4-nitro-2-{(E)-[2-(piperidin-1-yl)ethyl]iminomethyl}phenolACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Rocio J. Santos-Contreras The title Schiff base compound, 4-nitro-1-oxo-2-{(E)-[2-(piperidin-1-yl)ethyl]iminiomethyl}cyclohexadienide, C14H19N3O3, exists as a zwitterion, with the H atom of the phenol group being transferred to the imine N atom. The C=O, CAr,CAr and C,N bond lengths are in agreement with the oxocyclohexadienide,iminium zwitterionic form. The iminium H atom is engaged in a strong intramolecular hydrogen bond with the O atom of the keto group (N+,H...O) to form an S(6) motif. Soft C,H...O interactions in the ac plane lead to the development of hydrogen-bonded tapes, which are ,-stacked through the oxocyclohexadienide ring and iminium group. The significance of this study is in providing crystallographic evidence, supported by NMR and IR data, of the predominance of the oxocyclohexadienide,iminium zwitterion form over the noncharged canonical form in the title Schiff base. [source] Bis(acetone-,O)bis(N,N,-dimethylethylenediamine-,2N,N,)copper(II) diperchlorateACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2004Takashiro Akitsu The title compound, [Cu(C4H12N2)2(C3H6O)2](ClO4)2, is the first structurally characterized CuII complex having acetone as axial ligands. The complex adopts an elongated octahedral trans -[CuN4O2] coordination geometry, with the Cu atom having 222 site symmetry. The axial Cu,O(acetone) and in-plane Cu,N bond lengths are 2.507,(5) and 2.041,(3),Å, respectively. [source] | ||||||||||