A cobalt(III) compound of a 13‐membered cyclic tetra­amine: trans‐(12,12‐dimethyl‐1,4,7,10‐tetra­aza­cyclo­tetra­decane)diisothio­cyanato­cobalt(III) tetra­isothio­cyanato­zinc(II) ethanol solvate

The title compound, [Co(NCS)₂(C₁₁H₂₆N₄)]₂[Zn(NCS)₄]·C₂H₅OH, has two similar cations with the Co^III atom coordinated in a planar fashion by the 13‐membered cyclic tetra­amine, in the 1R,4S,7R,10S configuration, and with trans isothio­cyanate ligands. The six‐membered chelate ring is in a chair conformation, with one axially and one equatorially oriented methyl substituent [mean Co—N = 1.948 (2) Å]. The `opposite' chelate ring (N<sup>4</sup> and N<sup>7</sup>) is in an eclipsed conformation [mean Co—N = 1.928 (2) Å], and the `side' chelate rings have gauche conformations. The mean Co—N_NCS distance is 1.928 (2) Å. Both cations have one Co—N—C group nearly linear and the other appreciably bent, with mean Co—N—C angles of 178.7 (1) and 160.4 (1)°, respectively. The [Zn(NCS)₄]²⁻ anion is approximately tetra­hedral, with Zn—N = 1.951 (1)–1.986 (1) Å, N—Zn—N = 104.5 (1)–111.9 (1)° and Zn—N—C = 152.5 (1)–179.4 (1)°. One NH group is hydrogen bonded to the ethanol O atom and the other NH groups are bonded to thio­cyanate S atoms, forming a network.     

[N,N′‐Bis­(salicyl­idene)‐1,2‐di­phenyl‐(RS,SR)‐1,2‐ethane­di­amin­ato]­nickel(II)

In crystals of the title compound, [Ni(C₂₈H₂₂N₂O₂)], the coordination geometry around the Ni atom is square planar with a slight tetrahedral distortion. The five‐membered N,N′‐chelate ring adopts a distorted gauche conformation with the two phenyl groups in axial and equatorial orientations.     

Two ethyl 2-deoxy-α-d-hexo-3,7-pyranoso-3-octulosonate derivatives

In each of the two pyran­oid sugars, ethyl 2-deoxy-4,5,6,8-tetra-O-acetyl-α-d -gluco-3,7-pyran­oso-3-octulosonate, C₁₈H₂₆O₁₂, and ethyl 2-deoxy-4,5,6,8-tetra-O-benzyl-α-d -galacto-3,7-pyranoso-3-octulosonate, C₃₈H₄₂O₈, the anomeric configuration is α. The acetoxy­methyl substituent on the hexo­pyran­ose ring of the former compound and the ethoxy­carbonyl­methyl substituents in both sugars all have the gauche–trans conformation, while the benzyl­oxy­methyl substituent of the galacto­pyran­ose sugar has the trans–gauche conformation. In each structure, the anomeric hydroxy group forms an intramolecular hydrogen bond with the carbonyl O atom of the ethoxy­carbonyl­methyl substituent.     

[1,2‐Di­phenyl‐N,N′‐bis­(salicyl­idene)‐(RR,SS)‐1,2‐ethane­diyl­diamin­ato]­nitrido­manganese(V)

The title compound, [MnN(C₂₈H₂₂N₂O₂)], has a distorted square‐pyramidal coordination with an Mn[triple‐bond]N bond length of 1.516 (2) Å at the apical position. The five‐membered chelate ring adopts a gauche conformation with the two phenyl groups in equatorial orientations.     

Studies on the Metal Amide Bond 21. Metal Complexes of Chiral Phenyl-Substituted Bis-Picolinamide Tetradentates

Abstract

Two new C-phenyl bis-picolinamide tetradentates, N', N,'-bis(2-pyridinecarboxamide)-1,2-diphenyIethane (bpstienH₂) and N,N'-bis(2-pyridinecarboxamide)phenylethane (bpstyenH₂) together with their deproto-nated complexes of bivalent Cu, Ni and Pd have been prepared and characterised. A crystallographic analysis of the two copper(II) complexes is reported, with the S-bpstyenH₂ ligand found to be susceptible to racemisation under the warm basic conditions used in the syntheses.

{[N,N'-Bis(2-pyridinecarboxamido)-S',S-1,2-diphenylethane]copper(II)}, C₂₆H₂₀N₄O₂Cu is mono-clinic, spacegroup P2₁ (No. 4), with a = 11.170(3), b = 10.853(4), c = 18.570(7) Å, β = 103.74(3)°, Z = 4, with two molecules in the asymmetric unit. The structure was refined to R = 0.039 for 2519 reflexions. Each molecule is five coordinate with the fifth position occupied by an amide oxygen atom of a neighbouring molecule. These Cu-O(amide) distances are 2.554(7) and 2.757(6) Å. The stereochemistry of molecule 1 closely resembles a square-based pyramid, whereas that for molecule 2 approximates a distorted trigonal bipyramid. In each case the central five-membered chelate ring has a γ conformation with the two phenyl substituents occupying the axial positions in a rare configuration.

{Aqua[N,N'-bis(2-pyridinecarboxamido)phenylethane]-copper(II)}-sesquihydrate, C₂₀H₂₁N₄O₄₅Cu, is monoclinic, space group P2₁/c (No. 14), with a= 12.122(4), b= 10.691(2), c= 15.952(4)Å, β = 110.76(2)°, Z = 4. The structure was refined to R = 0.046 for 1939 reflexions. The stereochemistry of the five-coordinate copper atom approximates a square pyramid with the copper atom displaced 0.26 Å towards the apical water molecule (Cu-O 2.251(5) Å). In the enantiomer containing S-bpstyen the central five-membered chelate ring has a Δ conformation with the phenyl substituent occupying an equatorial position.

In solution the palladium(II) and nickel(II) deprotonated metal complexes of the S,S- and S- ligand forms are shown by ¹H NMR analysis, in conjunction with their chiroptical properties, to each have a X gauche central chelate ring conformation with the phenyl substituent(s) occupying axial positions.     

Steric and electronic evaluations of P(o‐tol)R2, where R is phenyl or cyclohexyl: crystal structures of SeP(o‐tol)R2

The crystal structures of SeP(o‐tol)R₂, where o‐tol is ortho‐tolyl (2‐methylphenyl) and R is Ph (phenyl), namely (2‐methylphenyl)diphenylphosphane selenide, C₁₉H₁₇PSe, or Cy (cyclohexyl), namely dicyclohexyl(2‐methylphenyl)phosphane selenide, C₁₉H₂₉PSe, were determined to aid in the evaluation of the steric and electronic behaviour of these analogous phosphane compounds. The compounds crystallized in similar monoclinic crystal systems, but are differentiated in their unit cells by a doubling of the number of independent molecules for R = Cy (Z′ = 2) and the choice of glide plane by convention. The preferred orientation for the o‐tolyl substituent obtained from the X‐ray structural analysis is gauche for R = Ph and anti for R = Cy (using the Se—P—C_ipso—C_ortho torsion angles as reference). Density functional theory (DFT) calculations showed both conformations to be equally probable and indicate that the preferred solid‐state conformer is probably due to the minimization of repulsion energies, resulting in a packing arrangement primarily featuring weak C—H…Se interactions and additional C—H…π interactions in the R = Ph structure. A detailed electronic and steric analysis was conducted on both phosphanes using Se—P bond lengths, multinuclear NMR ¹J_Se–P coupling constants, theoretical topological evaluation and crystallographic and solid‐angle calculations, and compared to selected literature examples. The results indicate that the use of the o‐tolyl substituent increases both the electron‐donating capability and the steric size, but is also dependent on whether the o‐tolyl group adopts a gauche or anti conformation. The single‐crystal geometrical data are unable to detect electronic differences between these two structures due to the somewhat large displacement parameters observed for the Se atom in the R = Cy structure.     

(2‐Aminoethanethiolato‐N,S)bis(ethylenediamine‐N,N′)cobalt(III) dinitrate

In the title compound, [Co(C₂H₆NS)(C₂H₈N₂)₂](NO₃)₂, the Co^III atom has a slightly distorted octahedral geometry, coordinated by one 2‐amino­ethane­thiol­ate and two ethyl­enedi­amine ligands. The three five‐membered chelate rings adopt a gauche conformation with the unfavoured (lel)₂(ob) form, which is ascribed to hydrogen bonds between the amine groups in the complex cation and the nitrate counter‐anions [N?O 2.900 (3)–3.378 (3) Å].     

trans‐[N,N′‐Bis­(salicyl­idene)­cyclo­hexane‐1,2‐diaminato]­nickel(II)–chloro­form (1/1)

In the title complex, trans‐{2,2′‐[cyclo­hexane‐1,2‐diyl­bis­(ni­t­rilo­methyl­idyne)]­di­phenol­ato‐κ⁴O,N,N′,O′}­nickel(II)–chloro­form (1/1), [Ni(C₂₀H₂₀N₂O₂)]·CHCl₃, the Ni atom has a square‐planar geometry, slightly tetrahedrally distorted. The Ni—N and Ni—O bonding distances are within the expected ranges for Ni–Schiff base derivatives. The di­imine bridge has a gauche conformation with the cyclo­hexyl ring almost coplanar with the NiN₂O₂ plane. The complex mol­ecules pack in dimers with an Ni?Ni distance of 3.59 (1) Å and form a three‐dimensional structure displaying a herring‐bone configuration. Channels are occupied by solvent mol­ecules, which are involved in C—H?O hydrogen bonds with the ligand O atoms.     

Weak C—H...Cl—Pd interactions toward conformational polymorphism in trans‐dichloridobis(triphenylphosphane)palladium(II)

A new triclinic polymorph of the title compound, [PdCl₂(C₁₈H₁₅P)₂], has two independent molecules in the unit cell, with the Pd atoms located on inversion centres. One molecule has an eclipsed conformation, whereas the second molecule adopts a gauche conformation. The molecules with a gauche conformation are involved in weak intermolecular C—H...Cl—Pd interactions with symmetry‐related molecules. It is suggested that C—H...Cl—Pd interactions are mainly responsible for the existence of conformational differences, which contribute to the polymorph formation. In the crystal, there are layers of eclipsed and gauche molecules separated by normal van der Waals interactions.     

Molecular structure and conformational analysis of chirai (−)-3-(4-bromobenzylidene)-1-isopropyl-2-methoxy-4-methylcyclohexene

(–)-3-(4-Bromobenzylidene)-1-isopropyl-2-methoxy-4-methylcyclohexene, capable of inducing spiral supramolecular ordering when introduced to nematic and some smectic mesophases, has been studied by an X-ray structural analysis. The crystals are orthorhombic; at 20 °Ca = 6.055(1),b = 13.282(3),c=20.734(4) Å,V=1668(1) ų,d _calc = 1.380 g cm^–3, space groupP2 ₁2₁2₁ Z=4. The cyclohexene ring has a conformation intermediate between a sofa and a half-chair. The methyl and methoxyl groups are in asyn orientation with respect to the mean plane of the cycle. The angle between the plane of the aryl substituent and the exocyclic double bond is 33°. The observed distortions of bond angles at unsaturated carbon atoms are typical of derivatives of benzylidenecyclohexene. Molecular mechanics calculations demonstrated that the conformation observed in the crystalline state is not the most favorable, and this conformation is stabilized through intermolecular interactions upon stacking in crystals. It was shown that the relative orientation of the methyl and methoxyl groups as well as the orientation of the aryl substituent substantially affect the conformation of the cyclohexene ring.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2437–2442, December, 1995.     

Characterization of Copper(II), nickel(II), cobalt(II) and palladium(II) complexes of vicinal oxime-imine ligands; induced chelate isomerism in the same molecule of the nickel(II) complex

Summary Metal complexes of the title ligands were characterized in order to determine the factors influencing the stability of chelate isomerism in the same molecule. The ligands were prepared by 1:1 condensation of isonitrosoacetylacetone (Hiso) with eithero-aminophenol (H₂ isoaph),p-aminophenol (H₂ isopph), or aniline (Hisoanil). The following complexes have been synthesized: [(isoaph)Cu]₄, (Hisoaph)₂Co, (Hisopph)₂ M·nH₂O (M=Ni(II), n=2;M=Pd(II), n=0;M=Co(II), n=2), [(isopph) Cu·H₂O]₂, and (isoanil)₂ M (M=Ni(II), Cu(II), Co(II), or Pd(II)). Both chelate rings in these metal complexes are five-membered. Transimination of one –C=N–C₆H₅ group to –C=NH in (isoanil)₂Ni produced a six-membered chelate ring in (isoim)Ni(isoanil). The induced chelate isomerism is ascribed to intermolecular hydrogen bonding of the imino-hydrogen and the basic nitrogen of the same six-membered chelate ring of an adjacent square planar molecule. Other types of hydrogen bondings with the oximato oxygen (intra- or intermolecular) favour the formation of five-membered chelate rings. Analytical, spectroscopic, and magnetic moment data are in accordance with the suggested formulations.Part of the Ph.D. thesis of Sana M. Imam     

2‐Amino‐8‐(2‐deoxy‐2‐fluoro‐β‐d‐arabinofuranosyl)imidazo[1,2‐a][1,3,5]triazin‐4(8H)‐one monohydrate,a 2′‐deoxyguanosine analogue with an altered Watson–Crick recognition site

The title compound, C₁₀H₁₂FN₅O₄·H₂O, shows an anti glycosyl orientation [χ = −123.1 (2)°]. The 2‐deoxy‐2‐fluoroarabinofuranosyl moiety exhibits a major C2′‐endo sugar puckering (S‐type, C2′‐endo–C1′‐exo, ²T₁), with P = 156.9 (2)° and τ_m = 36.8 (1)°, while in solution a predominantly N conformation of the sugar moiety is observed. The conformation around the exocyclic C4′—C5′ bond is −sc (trans, gauche), with γ = −78.3 (2)°. Both nucleoside and solvent molecules participate in the formation of a three‐dimensional hydrogen‐bonding pattern via intermolecular N—H...O and O—H...O hydrogen bonds; the N atoms of the heterocyclic moiety and the F substituent do not take part in hydrogen bonding.     

Crystal and Molecular Structure of the Macrocyclic Nickel (II) Complex Ni(C22H22H4): Dibenzo[b,i][5, 7, 12, 14] Tetramethyl [1, 4, 8, 11] Tetraazacyclotetradeca-2, 4, 7, 9, 12, 14-Hexaeneatonickel (II)

The crystal and molecular structure of the four-coordinate complex Ni(C₂₂H₂₂N₄) containing the tetramethyldibenzotetraaza[14] annulene ligand has been determined from three-dimensional X-ray diffraction data. The complex crystallized in the monoclinic space group C_2h⁵-P2₁/n with cell dimensions a=14.7967(10), b=11.2169(6), c=11.4510(6) Å, and β=98.467(5)° with Z=4. The final agreement indices from the least-square refinement of 245 variables with 3111 observations F>3σ(F), are R=0.050, R_w=0.037. The structure has a pronounced saddle-shaped conformation with Ni atom at the saddle point coordinated to four nitrogen atoms. The average Ni-N distance is 1.866(3) Å. The delocalized propane-1,3-diiminato chelate rings and the benzene rings are linked by nominally single C-N bonds.     

Analyse Conformationnelle par RMN du Proton des Oxo-2 Oxathiazannes-1,2,3 (Sulfinamates Cycliques) Diversement Substitués en 3, 4 et 6

In this study, carried out with 16 compounds, the chair form with an axial S?O group (CA) is found, in the absence of C-4, C-5 and C-6 substituents, to be the most stable (ΔG>8,4 kJ mole^?1), as previously reported for analogous cyclic sulfites. When methyl or tert-butyl substituents are present on the 4 and 6 carbon atoms, the conformation of the ring depends on their respective orientation towards the S?O group, and on the nature of the substituent of the nitrogen atom. For the trans isomers, the conformation remains anancomeric chair (CA) except when important gauche interactions exist: thus the strong Me/tBu gauche interaction in the 3-tert-butyl-4-t-methyl-2-r-oxo-1,2,3-oxathiazan induces a twist form with a 3,6-axis and an axial S?O group (CNA). When the 4- or 6-substituent is cis, the conformation of the sulfinamate may be either a chair form with an axial S?O group (CA), if the 4-substituent is a methyl, (even with a tert-butyl group in the 3-position which would be in the axial orientation) or a twist form with a 1,4-axis and an axial S?O group (COA) if the 4-substituent is a tert-butyl. Unlike cyclic sulfites, the equatorial SO chair form (CE) and the twist forms with a 2,3-axis and an isoclinal S?O group (CS, CS′) are rarely involved.     

Compounds of nickel(II) with 5SR,7RS,12SR,14SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradecane, rmL: The structures of [Ni(rmL)](ClO4)2 · 0.5H2O and cis-[Ni(rmL)(acac)]ClO4

The imine functions of [Ni(mL¹)](ClO₄)₂ (mL¹ = meso-7RS,14SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) are reduced by using NaBH₄ in acetonitrile/methanol to form the meso–meso and rac–meso isomeric cyclic tetramine complex cations [Ni(mmL²)]²⁺ and [Ni(rmL²)]²⁺ (mml² = 5RS,7RS,12SR,14SR- and rmL² = 5SR,7RS,12SR,14SR-5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradecane) in ca. 8:1 proportions. [Ni(rmL²)]²⁺ is also prepared from rmL², formed in <1% yield by the reduction of mL¹ by NaBH₄ in ethanol. Square planar singlet ground state (S = 1) salts [Ni(rmL²)](ClO₄)₂ and [Ni(rmL²)][ZnCl₄] and triplet ground state (S = 3) trans-di-ligand octahedral compounds trans-[Ni(rmL²)X₂] ,μ-Y-trans-[Ni(rmL²)Y] and folded macrocycle compounds cis-[Ni(rmL²)(acac)]CIO₄ (acac⁻ = pentane-2,4-dionato), cis-[{Ni(rmL²)}₂(C₂O₄)](ClO₄)₂, cis-[Ni(rmL²)(H₂O)₂](ClO₄)₂ and cis-[Ni(rmL²)X₂], X⁻ = Cl⁻, Br⁻, are described. The S = 1 salt 1SR,4SR,5SR,7RS,8RS,11RS,12SR,14SR-[Ni(rmL²)](ClO₄)₂ · 0.5H₂O has a disordered structure with Ni(II) in square planar coordination by the nitrogen atoms of the macrocycle, in N-configuration III, with Ni–N_mean = 1.96(2) Å. The six-membered chelate rings both have chair conformations, with the phenyl substituents equatorially oriented and with the methyl substituents disordered over axial and equatorial orientations. The S = 3 compound cis-1SR,4SR,5SR,7RS,8SR,11SR,12SR,14SR-[Ni(rmL²)(acac)]ClO₄ has N-configuration V. The macrocycle is folded along N¹–Ni–N⁸, adjacent to the phenyl substituents {N1–Ni–N8 = 176.45(6), N4–Ni–N11 = 98.16(6)°}, with mean Ni–N = 2.09(2) Å and mean Ni–O = 2.121(5) Å. Both six-membered chelate rings have chair conformations with the methyl substituents equatorially oriented, while one has the phenyl substituent equatorially and the other has it axially oriented. The structures of the isomeric [M(rmL²)(acac)]ClO₄, [M(rrL²)(acac)]CIO₄ and [M(mmL²)(acac)]ClO₄ compounds are compared.     

Chelatkomplexe LM/n von Übergangsmetallen mit Iminophosphin-säureamidato-Liganden R2P(NR′)2– (= L)

Chelate Complexes LM/n of Transition Metals with Phosphinoimidic Amidato Ligands R₂P(NR′)₂^– (= L) Reaction of LLi with metal halides or metal halide complexes affords chelate complexes LM/n (L = R₂P(NR′)₂^–; M = Cr⁺⁺⁺, Co⁺⁺, Ni⁺⁺, Zn⁺⁺). With the bulky ligand t-Bu₂P(NSiMe₃)₂^– and Ni(PPh₃)₂Cl₂ or Ni(dme)Br₂ (dme = dimethoxyethane) only halide bridged chelates [LNiHal]₂ (Hal = Cl, Br) containing tetrahedral chromophors NiN₂Hal₂ were obtained. Main objects of investigation were the bischelates L₂Ni 2 . 2 a (R = i-Pr, R′ = Me) and 2 c (R = Ph, R′ = Et) are planar, 2 b (R = i-Pr, R′ = Et) and 2 d–g (R, R′ = i-Pr, i-Pr; Ph, i-Pr; Et, SiMe₃; Ph, SiMe₃) tetrahedral. In solutions of 2 b and 2 c a conformational equilibrium planar (diamagnetic) tetrahedral (paramagnetic) exists that is shifted to the right with increasing temperature and is dominated by the tetrahedral ( 2 b ) or planar conformer ( 2 c ) at room temperature. As is the case with the isovalence electronic compounds [R₂P(S)NR′]₂Ni small substituents R′ apparently favour the planar state and in contrast to some complexes [R₂P(O)NR′]₂Ni no paramagnetic planar species 2 have yet been observed. These findings that are derived from the results of magnetic measurements and of UV/VIS as well as NMR spectroscopy are confirmed by crystal structure determinations: 2 a was found to be planar (orthorhombic; a = 3382.8(11), b = 1124.0(4), c = 8874(3); P2₁2₁2; Z = 6), and 2 g to be tetrahedral (monocline; a = 1268.4(2), b = 1806.8(2), c = 1971.6(2), P2₁/n; Z = 4). The bite angle NNiN of the chelate ligand in 2 a (ca. 77°) is similar to those in paramagnetic planar complexes [R₂P(O)NR′]₂Ni (NNiO 74–77°) and shows that a small chelate bite does not necessarily imply paramagnetism of planar Ni(II) complexes.     

The synthesis,crystal structures and antimicrobial studies of C‐methyl‐substituted hexaaza macrocycle of Cu(II) having aromatic pendant arm

Cu(II) complexes of 14‐membered hexaaza macrocyclic ligand with C‐methyl substituent of the type [CuL](X)₂ (where L = 3,10‐bisbenzyl‐6,13‐dimethyl‐1,3,5,8,10,12‐hexaazacyclotetradecane, and X = ClO₄⁻, PF₆⁻) were synthesized by tandem reaction. They were characterized by spectral and single‐crystal X‐ray diffraction techniques. The complexes show distorted octahedral geometry and the counter ions are weakly coordinated to the metal ion at the axial positions. The macrocyclic ring adopts the trans‐III configuration with six‐ and five‐membered chelate rings in chair and gauche conformation, respectively. It was observed that in the solid state the arrangement of the coordination sphere is distorted octahedral whereas, in solution, a square‐planar structure is predominant. The molar conductance of the complexes indicates that the axially bonded anions are almost dissociated in acetonitrile solution. The Electron Paramagnetic Resonance (EPR) spectrum of complex 1 is axial and consistent with a d_x² − _y² ground state. The [CuL](ClO₄)₂ was found to be active against the tested microorganism. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis,characterization and crystal structures of Nickel(II) complexes containing sterically hindering Benzimidazole ligands

The synthesis, characterization, and crystal structures of two Ni(II) complexes with N,N-bis[2-(2′-benzimidazolyl)ethyl]amine (bbiea) (1) and N,N-bis[2-(1′-methyl-2′-benzimidazolyl)ethyl]amine (bmbea) (2) are reported. The nickel complex Ni(bbiea)(O₂C₂H₃)(ClO₄) (3) crystallizes in the space group C2/c, with a = 35.830(7), b = 14.130(3), c = 10.756(2)?Å, and β = 103.04(3)°. Compound 4, Ni(bmbea)(NO₃)₂, crystallizes in the space group P2₁/c, with a = 17.024(5), b = 16.516(4), c = 8.692(2)?Å, and β = 91.31(2)°. In 3, the bbiea ligand is coordinated to the Ni(II) ion in a facial conformation, whereas the bmbea ligand in 4 adopts meridonal geometry. Both complexes contain a single benzimidazole chelate and the remaining coordination sites are occupied by solvent molecules and/or counterions. Reactions involving large excesses of ligand-to-metal and different solvents produced only the mono-chelated complexes 3 and 4. No evidence for formation of bis-chelated complexes with Ni(II) was observed by MALDI-TOF and ESI-mass spectroscopy. Ligand field parameters for 3 and 4 were determined to be 9606 and 9862?cm^?1, respectively.     

Synthesis,spectroscopic characterization and electrochemical behaviour of nickel(II) complexes with C-meso-5,5,7,12,12,14-hexamethylcyclotetradecane (Me6[14]aneN4). Crystal structure of {Ni(Me6[14]aneN4)|I2

Summary A series of complexes of formula {Ni(Me₆[14]aneN₄)X₂| (Me₆[14]aneN₄) = C-meso-5,5,7,12,12,14-hexamethyl-1,4,-8,11-tetraazacyclotetradecane and X = N₃ (1), NCO (2), NCS (3), AcO (4) or I (5) has been synthesized. The crystal structure of (5) has been determined by X-ray diffraction methods. The nickel atom is surrounded by a square-planar array of nitrogen atoms, giving a low-spin complex. The macrocyclic ligand shows the most stable conformation, the six-membered rings exhibiting the chair form while the gauche conformation is adopted by the five-membered rings. Spectroscopic and magnetic data for (1)–(4) are consistent with octahedral coordination around the nickel atom, which is achieved by four N atoms of the macrocyclic ligand in a single plane and by two azido-N (1), cyanato-N (2), thiocyanato-N (3) and carboxylato-O (4) groups occupying the axial positions. An electrochemical study of the oxidation of (1)–(5) has been carried out in nonaqueous solvents and the prospects of synthesis of the corresponding nickel(III) species are discussed in the light of the electrochemical data.     

Die Kristallstruktur von Bis(N,N-diethyl-N′ -benzoylselenoureato)nickel(II)

The Crystal Structure of Bis(N,N-diethyl-N′ -benzoylselenoureato)nickel(II) Ni(C₁₂H₁₅N₂OSe)₂ crystallizes in the monoclinic space group P2₁/c. The cell parameters are a = 11.399(3), b = 16.016(4), c = 14.910(6) Å, β = 104.64(3)° and Z = 4. The structure was solved with Patterson and direct methods and was refined to a final R-value of 5.43%. Nickel is coordinated to two N,N-diethyl-N′ -benzoylselenourea molecules to form a bidentally coordinated chelate complex with cis arrangement of the donor atoms. Coordinaton around the nickel atom is planar while the chelate rings diverge from planarity. The ethyl groups of one diethylamino group are disordered. The Ni? Se bond lengths are 2.244(1) and 2.264(1) Å, the Ni? O bond lengths are 1.871(4) and 1.883(4) Å, respectively.