Synthesis,Structure and Properties of Some 3d-Element Complexes with 2-[2-(Hydroxybenzylidene)-amino]-2-hydoxymethylpropane-1,3-diol

2-[2-(Hydroxybenzylidene)-amino]-2-hydoxymethylpropane-1,3-diol (HL) reacts with cobalt, nickel, copper and zinc chlorides, bromides and acetates in water–ethanol solutions and gives MLX · nH₂O and ML₂ · nH₂O complexes (M = Co, Ni, Cu, Zn; X = Cl, Br; n = 0–5). Single crystals of CuLBr were grown, and its crystal structure was determined by X-ray diffraction analysis. The crystals are tetragonal, a = 17.024(2), c = 8.720(2) Å, space group P 2₁ c, Z = 8, R ₁ = 0.0349. In the structure of this complex, the copper atom coordinates the deprotonated HL molecule. The coordination polyhedron of the central atom is an elongated tetragonal pyramid. Its base is built of the imine nitrogen atom, phenolic and alcoholic oxygen atoms, and bromine atom. The apex of the pyramid is occupied by the bromine atom of the adjacent complex connected with the initial complex by the plane of sliding reflection. Thus, the crystal contains infinite chains of complexes running along the c axis, the complexes being united by both bridging bromine atoms and O–H···O hydrogen bonds. The conclusions on the compositions and structures of the remaining compounds were made on the basis of elemental and combined thermal analyses, IR spectroscopy, and magnetic chemistry data. The copper halide complexes were found to have dimeric, and the other metal complexes monomeric, structures. In the synthesized complexes, the azomethine HL can function as a bidentate or tridentate ligand. The thermolysis of the coordination compounds proceeds through the stages of elimination of crystal water molecules (75–90°C) or inner-sphere water molecules (145–155°C) and complete thermal destruction (485–550°C).     

Synthesis,Spectral, Cyclic Voltammetric Studies,and Single Crystal X‐Ray Structure Determination of the Planar NiS2P2, NiS2PN,and NiS2PC Chromophores

Synthesis, spectral and cyclic voltammetric characterization of [Ni(dedtc)(4‐MP)₂](ClO₄) ( 1 ), [Ni(dedtc)(4‐MP)(NCS)]( 2 ), [Ni(dedtc)(PPh₃)(NCS)] ( 3 ) and [Ni(dedtc)(PPh₃)(CN)] ( 4 ) (dedtc = diethyldithiocarbamate, 4‐MP = tri(4‐methylphenyl)phosphine, PPh₃ = triphenylphophine) are reported. IR spectra of complexes 1‐4 show the characteristic thioureide (C‐N) bands at higher wave numbers compared to that of the parent dithiocarbamate complex [Ni(dedtc)₂]. The d‐d transitions are observed in the region 452—482 nm. The CV studies clearly show the presence of reduced electron density on the nickel ions in mixed ligand complexes 1‐4 compared to the parent dithiocarbamate. Single crystal X‐ray structure studies show all the complexes to containplanar NiS₂P₂, NiS₂PN, and NiS₂PC chromophores in keeping with the observed diamagnetism. In all the complexes the Ni‐S distances are asymmetric. The thioureide C‐N distance of the complexes 1‐4 are less thanthe C‐N distance observed in the parent [Ni(dedtc)₂].     

Catalytic efficacy of Schiff-base copper(II) complexes: Synthesis,X-ray structure and olefin oxidation

Three copper(II) Schiff-base complexes, [Cu(L¹)(H₂O)](ClO₄) (1), [Cu(L²)] (2) and [Cu(L³)] (3) have been synthesized and characterized [where HL¹ = 1-(N-ortho-hydroxy-acetophenimine)-2-methyl-pyridine], H₂L² = N,N′-(2-hydroxy-propane-1,3-diyl)-bis-salicylideneimine and H₂L³ = N,N′-(2,2-dimethyl-propane-1,3-diyl)-bis-salicylideneimine]. The structure of complex 1 has been determined by single crystal X-ray diffraction analysis. In complex 1, the copper(II) ion is coordinated to one oxygen atom and two nitrogen atoms of the tridentate Schiff-base ligand, HL¹. The fourth coordination site of the central metal ion is occupied by the oxygen atom from a water molecule. All the complexes exhibit high catalytic activity in the oxidation reactions of a variety of olefins with tert-butyl-hydroperoxide in acetonitrile. The catalytic efficacy of the copper(II) complexes towards olefin oxidation reactions has been studied in different solvent media.     

X-ray structural investigation of paramagnetic molecular compound of 2,5,9,12-tetramethyl-1,8-cis-1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) diperchlorate,trans-diaquo-2,5,9,12-eramehyl-1,8-trans-1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) diperchlorate,and water 2[cis-C14H28N4Ni](ClO4)2·[trans-C14H28N4Ni· 2H2O](ClO4)2·2H2O

The structure of molecular compoundI (2IA·IB·2H₂O), whereIA is a square-planar 2(e),5,9(a),12-tetramethyl-1,8-cis-1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) diperchlorate andIB is an octahedraltrans-diaquo-2(e),5,9(e),12-tetramethyl-1,8-trans-1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) diperchlorate has been investigated by X-ray diffractometric methods. Compound I crystallizes in an orthorhombic system, space groupPbca, Z=12,a=26.321(3),b=19.919(2),c=13.306(1) Å. The structure was solved by the heavy-atom method followed by a series of Fourier syntheses and refined by full-matrix least-squares to giveR=0.060 (for 3757 independent reflections). Conformations were ascribed to chelate rings and to the macrocyclic rings ofIA andIB, and the results were compared with those of some known 1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) complexes. The relative configurations were found 1RS,2SR,8RS,9RS (a racemate) forIA and 1R,2S,8S,9R (ameso-form) forIB. They differ each from the other by configuration on one nitrogen centre (N-epimeric compounds).     

Stereochemistry of rings. XI. Cyclohexane derivatives. Part 4. Structure of 1-oxocyclohexane-2,6-dione-4-spiro cyclopentane

The structure of the title compound was examined to elucidate the changes in the ring conformation of 1,3-cyclohexanedione derivatives when a heteroatom is introduced. The compound is orthorhombic, witha=17.540(3),b=7.457(2),c=6.661(2) Å and space groupP2₁2₁2₁. The structure was solved by direct methods and refined to a finalR of 0.072 for 527 observed reflections. The two mean ring planes form a dihedral angle of 88.9°.For Communication X see Bocelliet al. (1982a).For Part 3 see Bocelliet al. (1982b).     

X-ray structural investigation of two optically active 1N-epimers of 2,5,7,10,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) diperchlorate. A novel conformation of the macrocyclic ligand

The structures oftrans-1NH,8NH- (I) andcis-1NH,8NH-(II)-2,5,7,10,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel(II) diperchlorates have been investigated by X-ray diffractometric methods. CompoundI crystallizes in a monoclinic system, space groupP2₁,Z=4,a=11.225(1),b=13.710(1),c=15.898(2) Å,=109.22(1)°. CompoundII crystallizes in an orthorhombic system, space groupP2₁2₁2₁,Z=4,a=15.529(2),b=14.129(2),c=10.621(1) Å. The structures were solved by the heavy-atom method followed by a series of Fourier syntheses, and refined by full-matrix least squares to give forI andII R=0.051 (for 3787 independent reflections) andR=0.048 (for 1494 reflections), respectively. Conformational analysis of chelate rings and of the macrocyclic ring was performed forI andII, and the results were compared with those of some known 1,4,8,11-tetraazacyclotetradeca-4,11-dienenickel (II) complexes. A novel conformation of the macrocycle was found in cationI. Conformations of the methyl groups are forI andII 2(a),7(e),10(a),14(e) and 2(a),7(e),10(a),14(a), respectively, with a 1,3-syn-axial interaction of the 2,14-methyl groups inII. The absolute configuration of cationI is 1N(S), 2(R), 7(R), 8N(S), 10(R), 14(S), and differs from that of cationII by 1N(R) exclusively (1N-epimeric compounds).     

Crystal and molecular structure of inner-chelatecis-1,7-dioxa-4,10-diazacyclododecane-4,10-diacetatocopper(II) dihydrate

cis-1,7-Dioxa-4,10-diazacyclododecane-4,10-diacetato-copper(II) dihydrate crystallizes in the monoclinic space groupP2₁/n witha=11.318(2),b=12.129(2),c=12.160(2) Å,=110.09(1)°, andZ=4. The structure was solved by the heavy-atom technique, followed by full-matrix least-squares refinement with anisotropic thermal parameters for non-H atoms. The Cu(II) atom is in a very distorted octahedral environment, with two nitrogen and two oxygen atoms located approximately coplanar with Cu(II), and the two remaining oxygen atoms in apical positions forming an angle of about 147° at Cu(II). The 12-membered ring has noncrystallographicmm2 symmetry. Two five-membered rings containing acetato groups are located in acis arrangement relative to the macrocyclic ring.     

Amino­pyrimidine–carboxyl­(ate) interactions in trimethoprim maleate,an antifolate drug

In the title cocrystal, trimethoprim maleate [2,4‐di­amino‐5‐(3,4,5‐tri­methoxy­benzyl)­pyrimidin‐1‐ium maleate], C₁₄H₁₉­N₄O₃⁺·­C₄H₃O₄^?, the trimethoprim mol­ecule is protonated at N1. The carboxyl group of the maleate ion makes a specific double hydrogen bond of type N—H?O with the 2‐amino group and the protonated N1 atom of the trimethoprim cation which is similar to the carboxyl­ate–trimethoprim cation interaction observed in the complex of di­hydro­folate reductase with trimethoprim. The pyrimidine moieties of trimethoprim cations are centrosymmetrically paired through a pair of N—H?N hydrogen bonds involving the 4‐amino group and the pyridinium N3 atom of a symmetry‐related molecule. One of the O atoms at the maleate carboxyl­ate group bridges the 2‐­amino and 4‐amino groups on either side of the paired trimethoprim cations. The other O atom of the carboxyl­ate group forms an intramolecular O—H?O hydrogen bond with the carboxyl group. These characteristic hydrogen bonds result in infinite two‐dimensional aggregation of rings into a supramolecular ladder, which is further crosslinked through weak C—H?O interactions with methoxy groups of neighbouring trimethoprim mol­ecules to form a layered structure.