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.     

Influence of the Coordination of Donor Solvent Molecules to 1,4,7,10-Tetramethyl-1,4,7,10- tetraazacyclododecanenickel(II) and Analogous Nickel(II) Complexes on Their Steric Factors

Coordination equilibrium constants (K _NiS) of some donor solvent molecules to 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecanenickel(II) ([Ni(Me₄[12]aneN₄)]²⁺) were determined in nitrobenzene (a noncoordinating bulk solvent). The first (K _NiS1) and second stepwise coordination equilibrium constants (K _NiS2) for 1,4,7,10-tetraazacyclododecanenickel(II) ([Ni([12]aneN₄)]²⁺), 1,4,8,11-tetraazac yclotetradecane- nickel(II) ([Ni([14] aneN₄)]²⁺), 1,4,8,11-tetrathiacyclotetra-decanenickel(II) ([Ni([14]aneS₄)]²⁺) were also reinvestigated. The K _NiS values for [Ni(Me₄[12]aneN₄)]²⁺ were compared to those of [Ni([12]aneN₄)]²⁺, (1R,4S, 8R,11S)-1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecanenickel(II) (R,S,R,S-[Ni(Me₄[14]aneN₄)]²⁺), R,R,S,S-[Ni(Me₄[14]aneN₄)]²⁺, [Ni([14]aneN₄)]²⁺, and [Ni([14]aneS₄)]²⁺. Coordination of pyridine (Py), N,N,N′,N′-tetramethylurea (TMU), and N,N-dimethylacetamide (DMA) to [Ni(Me₄[12]aneN₄)]²⁺ was observed, although these donor solvent molecules did not coordinate to R,S,R,S-[Ni(Me₄[14]aneN₄)]²⁺. The K _NiS values for Py, TMU, and DMA are 7.9, 2.8, and 9.0 dm³⋅mol⁻¹, respectively. Some hydrogen-bonding waters were coordinated to R,S,R,S-[Ni(Me₄[14]aneN₄)]²⁺, but such waters did not coordinate to [Ni(Me₄[12] aneN₄)]²⁺. Also, the K _NiS2 values were larger than the corresponding K _NiS1 values for [Ni([14]aneS₄)]²⁺. Furthermore, the K _NiS1 values for [Ni([12]aneN₄)]²⁺ were the largest among these nickel(II) complex cations. The K _NiS, K _NiS1, and K _NiS2 values are discussed in terms of properties of the donor solvents and steric strains of these nickel(II) complex cations.     

Synthesis, characterization and catalytic oxidation of cyclohexene with molecular oxygen over host (zeolite-Y)/guest (nickel(II) complexes of R2[12]1,3-dieneN2O2 and R2[13]1,4-dieneN2O2; R = H, Me, Ph) nanocatalyst (HGN)

12- and 13-Membered diaza dioxa Schiff-base nickel(II) complexes were successfully prepared in a nanoscale microreactor by the template condensation of (1,8-diamino-3,6-dioxaoctane)nickel(II) complex with bifunctional diketones within the nanodimensional pores of zeolite Y. The host–guest nanocatalyst (HGN); ([Ni((R₂[12]1,3-dieneN₂O₂)]²⁺-NaY, [Ni(R₂[13]1,4-dieneN₂O₂)]²⁺-NaY; R = H, Me and Ph) is catalytically very efficient as compared to other neat complexes for oxidation of cyclohexene with molecular oxygen as oxidant in the absence of solvent at 70 °C, affording 2-cyclohexene-1-ol and 2-cyclohexene-1-one.     

Structure and Highly Stereoselective Formation of 1:2 Metal-to-Ligand complexes with triamine 2,6-bis(pyrolidin-2-yl)pyridine. meso-[2,6-bis(pyrrolidin-2yl)pyridine]nickel(II) (meso-[Ni(bpp)2]2+), a Metal Complex with S4 Symmetry

The X-Ray structures of the 1:1 copper(II) complexes with racemic and opticall active (+)-(R,R)-(2,6-bis(pyrrolidin-2-yl)pyridine ((+)-bpp; (+)- I ) were determined. Whereas the perchlorate 1 of racemic complex contains the monomeric units with perfect C₂ symmetry, the sulfate of the optically active compound crystallizes as a coordination polymer composed of sequences of three different five-coordinate units linked by sulfate bridges around a threefold screw axis (see 2 ). Formation of the 1:2 complexes of nickel( II ) with (±)-bpp is shown to be highly stereoselective. Acidimetric titrations and CD measurements indicate that the equilibrium mixture contains 99% of the meso-complex 3 belonging to the point group S₄ and only 0.5% of each enantiomer of the C₂-symmetric optically active forms. The S₄ symmetry of meso-[Ni{(+)-bpp}{(?)-bpp}]ClO₄)₂ ( 3 ) was confirmed by X-ray analysis. The formation of binary complexes of cobalt(II), zinc(II), and cadmium(II) with (±)-bpp shows an excess of 28, 34, and 8%, respectively, of the meso-form over the statistical amount. CD and UV/VIS measurement show a pH-dependent high spin/low spin equilibrium between the octahedral [Ni(bpp)(H₂O)₃]²⁺ and the square-planar [Ni(bpp)OH]⁺ in aqueous solution.     

A novel hydrogen‐bonded microporous framework constructed from two different metal complexes

A hydrogen‐bonded coordination supramol­ecule, (meso‐5,7,­7,­12,14,14‐hexa­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane‐κ⁴N)­nickel(II) [N,N‐o‐phenylenebis­(oxamato)­‐κ⁴O,N,N′,O′]nickelate(II) dihydrate, [Ni(C₁₆H₃₆N₄)][Ni(C₁₀H₄N₂O₆)]·2H₂O or [Ni(meso‐cth)]­[Ni(opba)]·2H₂O, has been prepared and characterized by X‐ray crystallographic analysis. The two complex ions, i.e. [Ni(meso‐cth)]²⁺ and [Ni(opba)]^2?, are hydrogen bonded to each other, resulting in two‐dimensional neutral supramolecular sheets. The sheets stack along the a direction to produce a three‐dimensional architecture with one‐dimensional channels in which hydrogen‐bonded chains of water mol­ecules are included.     

A chemical oscillating reaction in NaBrO3-pyruvic acid-H2SP4--[Ni(Me2[14]1,3-diene N4)]2+ system

In this paper we report a chemical oscillation catalyzed by [Ni(Me₂[14]l,3-diene N₄)]²⁺ (Me₂[14]1,3-diene N₄ denotes 2,3-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,3-diene) in BrO₃-pyruvic acid-H₂SO₄ system. The domain of the existence of the oscillation waa obtained. The effect of initial concentration of the components on the oscillation were studied. The features of the oscillations were described in detail. We also examined the effects of Ag⁺, Hg²⁺, CCl₄, free radical inhibitors, etc. on the oscillations.     

Metal Complexes with Macrocyclic Ligands. Part XXXIX. Mono- and binuclear copper(II) complexes of a bridging bis[1, 4, 7-triazacyclononane]

The new bis-macrocycle 1, 1′-[(1H-pyrazol-3], 5-diyl)bis(methylene)bis[1, 4, 7-triazacyclononane] ( 1 ) was synthesized and its complexation with Cu²⁺ studied. Potentiometric and spectrophotometric titrations indicate that, in addition to the mononuclear species [Cu(LH₂)]⁴⁺, [Cu(LH)]³⁺, [CuL]²⁺, and [Cu(LH_?1)]⁺, binuclear complexes such as [Cu₂L]⁴⁺, [Cu₂(LH_?1)]³⁺, and [Cu₂(LH_-2)]²⁺ are also formed in solution. The stability constants and spectral properties of these are reported. The binuclear species [Cu₂(LH_?1)]³⁺ specifically reacts with an azide ion to give a ternary complex [Cu₂(LH_?1)(N₃)]²⁺, the stability and structure of which were determined spectrophotometrically and by X-ray diffraction, respectively. The two Cu²⁺ ions are in a square-pyramidal coordination geometry. The axial ligand is one of the N-atoms of the 1, 4, 7-triazacyclononane ring, whereas at the base of the square pyramid, one finds the other two N-atoms of the macrocycle, one N-atom of the pyrazolide and one of the azide, both of which are bridging the two metal centres. In [Cu₂(LH_?1)(N₃)]²⁺, a strong antiferromagnetic coupling is present, thus resulting in a species with a low magnetic moment of 1.36 B.M. at room temperature.     

Synthese optisch aktiver Nickel-Komplexe mit porphinoidem Ligandsystem

Synthesis of Optically Active Porphine-type Nickel Complexes Both enantiomers of [1-methyl-8 H-HDP]nickel-perchlorate

1 For nomenclature see footnote 5 in this paper.

( 2a and 2b , respectively) have been synthesized by the following reaction sequence: (a) base induced addition of (?)-( R )-2-octanol to 1 , (b) separation of the two diastereomeric monoadducts 4a and 4b , (c) reaction with methyl magnesium iodide containing an excess of methyl iodide, (d) acid induced elimination of 2-octanol from the diadducts 6a and 6b . By a similar procedure both enantiomers of [1-butyl-8 H-HDP] nickel-perchlorate ( 3a and 3b , respectively) have been prepared. The reaction of 3a with butyl lithium yields in a kinetically controlled addition predominantly the optically active cis -1, 11-dibutyl adduct 8 and in minor quantity the meso - cis -1, 11-dibutyl adduct 9 .     

Experimental and computational studies of the macrocyclic effect of an auxiliary ligand on electron and proton transfers within ternary copper(II)-Histidine complexes

The dissociation of [Cu^II(L)His]^•2+ complexes [L=diethylenetriamine (dien) or 1,4,7-triazacyclononane (9-aneN₃)] bears a strong resemblance to the previously reported behavior of [Cu^II(L)GGH]^•2+ complexes. We have used low-energy collision-induced dissociation experiments and density functional theory (DFT) calculations at the B3LYP/6-31+G(d) level to study the macrocyclic effect of the auxiliary ligands on the formation of His^•+ from prototypical [Cu^II(L)His]^•2+ systems. DFT revealed that the relative energy barriers of the same electron-transfer (ET) dissociation pathways of [Cu^II(9-aneN₃)His]^•2+ and [Cu^II(dien)His]^•2+ are very similar, with the ET reactions of [Cu^II(9-aneN₃)His]^•2+ leading to the generation of two distinct His^•+ species; in contrast, the proton transfer (PT) dissociation pathways of [Cu^II(9-aneN₃)His]^•2+ and [Cu^II(dien)His]^•2+ differ considerably. The PT reactions of [Cu^II(9-aneN₃)His]^•2+ are associated with substantially higher barriers (>13 kcal/mol) than those of [Cu^II(dien)His]^•2+. Thus, the sterically encumbered auxiliary 9-aneN₃ ligand facilitates ET reactions while moderating PT reactions, allowing the formation of hitherto nonobservable histidine radical cations.     

Copper(II), nickel(II) and cobalt(III) complexes of the macrocyclic ligand C-meso-7,14-diphenyl-5,6-butano-12,13-butano-1,4,8,11-tetraazacyclotetradeca-4,11-diene

Summary Metal complexes of the macrocyclic tetraaza ligand C-meso-7,14-diphenyl-5,6-butano-12,13-butano-1,4,8,11-tetraazacyclotetradeca-4,11-diene (L) are described. The copper(II) and nickel(II) complexes, isolated as their perchlorate salts, are 4-coordinate species. Several cobalt(III) complexes,trans-[CoLX₂]⁺(X = Cl^–, Br^–, NO ₂ ^– or N ₃ ^– have also been characterised. The most probable stereochemistry of the ligand in the metal complexes is the C-meso-N-meso arrangements of the chiral centres. The N-meso stereochemistry leads to the bulky phenyl groups lying in equatorial positions. I.r. and d-d spectra are reported for the various complexes described.     

Synthesis and circular dichroism studies of some cobalt(III) complexes containing 2,2′ bipyridine, 1,10 phenanthroline,and some optically active amino acids

Two series of cobalt(III) complexes were synthesized and spectrally analyzed, [Co(2,2′-bipyridyl)₂(aa)]I₂ and [Co(1,10-phenanthroline)₂(aa)]I₂ (where the letters aa refer to an optically active, bidentate amino acid). The following amino acids were used: l-alanine, glycine, l-leucine, l-phenylalanine, and l-proline.This research is an analogue to the chemical systems studied by Mason et al.^1,2 They investigated complexes such as [Co(phen)₃]³⁺, [Co(dipy)₃]³⁺, [Co(phen)₂(dipy)]³⁺, [Co(dipy)₂(phen)]³⁺, [Co(phen)₂(ox)]²⁺, and [Co(dipy)₂(ox)]²⁺. The series of [Co(dipy)₂(na)]²⁺ and [Co(phen)₂(na)]²⁺ complexes, where the letters na refer to a non-optically active, bidentate ligand, have exhibited exciton-splitting. We used optically active amino acids to ascertain whether or not the exciton-splitting phenomenon would occur when a non-optically active ligand was substituted by an optically active amino acid. In addition, a series of optically active amino acids was selected with the intention of determining whether small differences among the amino acid ligands would affect the circular dichroism (CD) spectra of the different complexes and if the formation of these complex ions would be steroselective.     

Molecular Structure of the Macrocyclic Ligand Complex (5, 7, 12, 14-Tetraethyl-7, 14-Dimethyl-1, 4, 8, 11-Tetraazacyclotetra Decane) Nickel (II) Perchlorate

The structure of macrocyclic ligand complex, (5, 7, 12, 14-tetraethyl-7, 14-dimethyl-1, 4, 8, 11-tetraazacyclotetra decane)·Ni^II·(ClO₄)₂ has been determined by X-ray diffraction with three dimensional counter data. This compound, C₂₀H₄₄N₄Ni^II·(ClO₄)₂, crystallizes in orthorhombic space group Pbca, with cell parameters a=14.369, b=11.752, c=16.207 A, V=2736.8 A³, determined from Syntex Pl autodiffractomter. The formula weight (598.21) and a measured density of 1.45 gm cm^?3 (by flotation) indicate the presence of four molecules per unit cell (D_c=1.452 gm cm^?3). The structure was solved, using Patterson and Fourier methods and refined by full-matrix least-squares techniques to a reliability index, R(F) of 0.09, based on 1480 independent observed data corrected for absorption, L-p factors. In this molecule, in addition to the usual covalent and ionic bonds, there exist two hydrogen bonds between the perchlorate ions and the amine groups. The Ni and the four N atoms are coplanar. The six membered ring subtends a larger angle (93.5(3)°) over the Ni atom than the five membered ring (86.5(3)°) does. The former belongs to the chair form and the latter pertains to the gauche form.     

Thermodynamic Studies on the Complexation Reactions of copper(II) Macrocyclic Tetramine Complexes with Monodentate Ligands: I. RAC-5, 7, 7, 12, 14, 14-Hexamethyl-l, 4, 8, 11-Tetraazacyclotetradecane-Copper(II) (Blue) with-Halide Ions

The possibility of a trigonal bipyramidal structure for [Cu(tet b)X]⁺ (blue) (where X=Cl, Br, I) is supported by the observation of two distinct d-d bands, which are assigned as and d, d_xy→d and d_xz, d_yz→d transitions respectively. The stability constants for the formation of [Cu(tet b)X]⁺ (blue) from [Cu(tet b)]^z+ (blue) and X^? were determined by spectrophotometric method at 25°, 35° and 45°C. The corresponding δH° and δS° values were obtained from the variations of the stability constants between 25° and 45°C     

Octapalladium Strings Trap C60 and C70 Fullerenes Affording Metal-Chain-Wired Bucky Balls

Reactions of Pd₈ strings supported by meso-Ph₂PCH₂P(Ph)CH₂P(Ph)CH₂PPh₂ (meso-dpmppm) ligands, [Pd₈(meso-dpmppm)₄(L)₂]⁴⁺ (L=CH₃CN ( 1 ), XylNC ( 2 )) with C₆₀ resulted in the exclusive formation of unprecedented metal-chain-wired C₆₀ bucky balls, [{Pd₄(meso-dpmppm)₂(L)}₂(C₆₀)]⁴⁺ (L=CH₃CN ( 11 ), XylNC ( 12 )), in which a C₆₀ fullerene is trapped in the central Pd–Pd junction, as unambiguously established by spectroscopic, X-ray crystallographic, and theoretical techniques. The similar reaction of Pd₈ strings supported by rac-dpmppm, [Pd₈(rac-dpmppm)₄(CH₃CN)₂]⁴⁺ ( 3 ) also afforded a racemic mixture of [{Pd₄((R*,R*)-dpmppm)₂(CH₃CN)}₂(C₆₀)]⁴⁺ ( 13 ) without scrambling the Pd₄ fragments with (R,R)- and (S,S)-dpmppm ligands. Consequently, those of enantiopure chiral Pd₈ strings, [Pd₈((R*,R*)-dpmppm)₄(CH₃CN)₂]⁴⁺, certainly afforded chiral bucky balls of [{Pd₄((R*,R*)-dpmppm)₂(CH₃CN)}₂(C₆₀)]⁴⁺ ( 13 _RR and 13 _SS ), that exhibit mirror-image circular dichroism spectra. The reactions of 1 and 2 were also applied for trapping a C₇₀ fullerene to give 2 : 1 adducts of [{Pd₄(meso-dpmppm)₂(L)}₂(C₇₀)]⁴⁺ (L=CH₃CN ( 21 ), XylNC ( 22 )). These results provide useful information for creating a platform to develop dimensionally and chirality controlled metal–carbon nanocomposite materials.     

Aggregate, Polymer and Cluster Formation from Metal-Imino Carboxylate Complexes

Reaction of tris-(2-aminoethyl)amine (tren) andthe sodium salt of an -ketocarboxylic acid, typically sodium pyruvate, affordsin the presence of a lanthanide ion aseries of complexes and aggregates includingmononuclear, cyclic tetranuclear and polymerspecies of [L¹]^3- ([L¹]^3-=N[CH₂CH₂N=C(CH₃)COO^-]³).The aggregation of these and related d-block elementcomplexes with Na⁺ ions leadsto the formation of polymeric materials, and thefactors influencing the formation and controlof these various aggregation states are discussed.Metal cations also template the aggregationof the fragment [Ni(L²)] ([L²]^2- =CH₂[CH₂N = C(CH₃)COO^-]₂)to give, in high yield, the polynuclearaggregates {[Ni(L²)]₆M}^x+(M = Nd, Pr, Ce, La, x = 3; M = Sr, Ba, x = 2). The structures of{[Ni(L²)]₆M}^x+ show aninterstitial twelve co-ordinate, icosahedralcation M^x+ encapsulated by six [Ni(L²)]fragments. In the presence ofNa⁺, aggregation of [Ni(L²)] fragments affords {[Ni(L²)]₉Na₄(H₂O)(MeOH)(ClO₄)}³⁺ thestructure of whichshows four Na⁺ ions templating the formation ofa distorted tricapped trigonal prismatic[Ni(L²)]₉ cage. Thus, control overconstruction of various polynuclear cages viaself-assembly at octahedral junctions can beachieved using main group, transition metaland lanthanide ion templates.     

An economical synthesis of dibenzocyclamnickel(II) and a metal-free macrocycle with tetramethyl substituents

The cationic dibenzocyclamnickel(II) complex, [Ni(Me₄Bzo₂[14]aneN₄)]²⁺, was obtained in good yield by Fe/HCl reduction of the corresponding tetraazaannulene complex [Ni(Me₄taa)], (1) {Me₄Bzo₂[14]aneN₄ = 5,7,12,14-tetramethyldibenzo[b,i]-1,4,8,11-tetraazacyclotetradecane; Me₄taa = 5,7,12,14-tetramethyldibenzo[b,i]-1,4,8,11-tetraazaannulene(2-)}. The orange–red product was isolated as the chloride (2) and perchlorate (3) salts. Analogous reduction with Zn/HCl yielded a diprotonated silky-white product [Ni(Me₄Bzo₂[14]aneN₄-H₂)][ZnCl₄]₂, (4). In the dry state, complex (4) is stable only under an HCl atmosphere and readily dissociates to give a solution of (2) when dissolved in polar solvents. Complexes (2) and (3), upon treatment with an excess of aqueous NaCN, undergo facile demetallation yielding the metal free macrocycle Me₄Bzo₂[14]aneN₄, (5). These compounds were characterized using a combination of i.r., u.v.–vis., ¹H-n.m.r., mass spectroscopy and voltammetry techniques. Unlike the parent tetraazaannulene complex (1), the reduced macrocycle complex, [Ni(Me₄Bzo₂[14]aneN₄)]²⁺ exhibits mild catalytic activity towards electro-reduction of CO₂ in MeCN solution.     

Rhodium (I)-katalysierte Reaktionen der [2+4]-Cycloaddukte aus 3,4-Dimethoxyfuran und Acetylendicarbonsäure-estern

[2+4]-Cycloaddition Products of 3,4-Dimethoxyfuran with Acetylenedicarboxylates and Their Transformations under the Influence of Rhodium(I) Catalysts 3,4-Dimethoxyfuran ( 1 ) readily reacts with acetylenedicarboxylates ( 2 ) at room temperature in a [2+4]-cycloaddition to give a mono-( 3 ) and several di-addition products. 90% of the latter consists of the endo-exo compound 4 . Under the influence of catalytic amounts of [Rh(CO)₂Cl]₂ the mixture of mono- and di-adducts in methanolic solution is smoothly transformed into endo-5,5,6-trimethoxy-7-oxabicyclo [2.2.1]hept-2-ene-2,3-dicarboxylate

1 Alle Verbindungen sind racemisch. Die Formeln stellen jeweils nur ein Enantiomeres dar.

(5) , 3-hydroxy-4,5-dimethoxyphthalate ( 6 ) and (I R *, 2 S *, 4 R *, 5 R *, 7 R *, 11 R *, 12 R *) -5,8,8,9,12-pentamethoxy-3,6-dioxatetracyclo [5.3.1.1 ^2,5 . 0 ^4,11 ]dodec-9-ene-1,11-dicarboxylate ( 7 ).     

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.     

Unexpected formation of chiral single crystals of {NH(n-C3H7)3[MnIICrIII(C2O4)3]}, A 2D oxalate-based material

In an attempt to obtain chiral single crystals of a two-dimensional (2D) bimetallic oxalate-based material by enantioselective auto-assembling of Mn²⁺ and (rac)-[Cr(C₂O₄)₃]^3? templated by the optically active complex (+)-(Rp)-[1-CH₂(n-C₃H₇)₃-2-CH₃(C₅H₃)Fe(C₅H₅)]⁺, we obtained the unexpected 2D network species {NH(n-C₃H₇)₃[MnCr(C₂O₄)₃]}. X-ray diffraction determination of the structure reveals that the complex crystallizes in the enantiomorphous space group P6₃. The interlayer spacing of 7.93?Å?is the lowest found so far for 2D, bimetallic, oxalate-bridged compounds.     

Room Temperature Synthesis of New Thiostannates by Slow Interdiffusion of Different Solvents

The new compounds [Ni(L₁)][Ni(L₁)Sn₂S₆]_n · 2H₂O ( I ) and [Ni(L₂)]₂[Sn₂S₆] · 4H₂O ( II ) containing the macrocyclic ligands L₁ (L₁ = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane) and L₂ (L₂ = 1,8-diethyl-1,3,6,8,10,13-hexaazacyclotetradecane) were prepared at room temperature by overlaying an aqueous solution of Na₄SnS₄ · 14H₂O with the [Ni(L₁)](ClO₄)₂ complex dissolved in CH₃CN ( I ) or by overlaying a solution of the [Ni(L₂)](ClO₄)₂ complex dissolved in DMSO with an aqueous solution of Na₄SnS₄ · 14H₂O ( II ). The slow interdiffusion of the two solvents guarantees supersaturation in the interface region of the solvents so that crystallization of the compounds occurs. In the structure of I one Ni²⁺ cation has bonds to S^2– anions of the thiostannate anion thus generating chains along [100]. This cation is in an octahedral environment of four N atoms of L₁ and two S atoms of the [Sn₂S₆]^4– anion. The second [Ni(L₁)]²⁺ complex exhibits a square-planar coordination geometry. These [Ni(L₁)]²⁺ complexes and water molecules are located between the chains. In the structure of II isolated [Sn₂S₆]^4– anions and [Ni(L₂)]²⁺ cations are observed. The Ni²⁺ cations are fourfold coordinated by N atoms of the L₂ ligand and feature also a square planar environment.