cis-Di­chloro­bis­(triethyl­arsine)­platinum(II) and cis-di­chloro­bis­(triethyl­phosphine)­platinum(II)

The crystal structure of cis-[PtCl₂(C₆H₁₅As)₂], (I), is isostructural with a previously reported structure of cis-[PtCl₂(C₆H₁₅P)₂], (II). A new polymorph of (II) is also reported here. Selected geometrical parameters in the arsine complex are Pt—Cl 2.3412 (12) and 2.3498 (13), Pt—As 2.3563 (6) and 2.3630 (6) Å, Cl—Pt—Cl 88.74 (5), As—Pt—As 97.85 (2), and Cl—Pt—As 171.37 (4) and 177.45 (4)°. Corresponding parameters in the phosphine complex are Pt—Cl 2.364 (2) and 2.374 (2), Pt—P 2.264 (2) and 2.262 (2) Å, Cl—Pt—Cl 85.66 (9), P—Pt—P 98.39 (7), and Cl—Pt—P 170.26 (7) and 176.82 (8)°.     

cis-Bis[N1,N2-bis(trimethylsilyl)benz­amidinato-κ2N1,N2]chloro(4-tolyl­imido-κN)vanadium(V)

The title complex, [V(C₇H₇N)(C₁₃H₂₃N₂Si₂)₂Cl], consists of a V metal centre coordinated to five N atoms and a Cl⁻ ion in a pseudo-octahedral arrangement. The N atoms of the benzamidinate ligands form two four-membered chelate rings to V, with bite angles of 63.59 (8) and 64.36 (8)°, whilst the fifth N atom is from a p-tolyl­imido ligand [V—N—C 172.2 (2)°] located cis with respect to the Cl⁻ ion [Cl—V—N_imido 96.96 (8)°].     

N,N′-(1,2-phenylene)bis­(pyridine-2-carboxamide) and N,N′-(1,2-cyclohexanediyl)bis(pyridine-2-carbox­amide) toluene hemisolvate

The crystal structures of N,N′-(1,2-phenyl­ene)­bis­(pyridine-2-carbox­amide), C₁₈H₁₄N₄O₂, (I), and N,N′-(1,2-cyclo­hexane­diyl)­bis­(pyridine-2-carbox­amide) have been determined, the latter compound as the toluene hemisolvate, C₁₈H₂₀N₄O₂·0.5C₇H₈, (II). In (I), the benzene ring is nearly coplanar with one of the pyridine rings and forms a dihedral angle of 59.4 (1)° with the other. However, in (II), the dihedral angle of the two pyridine rings is 70.0 (1)°.     

Di­bromo{N-[2-(di­phenyl­phosphino)­benzyl­idene]-2,6-diiso­propyl­aniline-κ2N,P}nickel

In the title compound, [NiBr₂(C₃₁H₃₂NP)], (I), the second reported example of a nickel–imino­phosphine N,P-chelate in which the Ni atom has tetrahedral coordination, the Ni coordination is distorted as a consequence of the N—Ni—P chelate bite angle of 91.07 (6)° compensated by the Br—­Ni—­Br angle of 126.385 (18)°. In (I) and its analogue, viz. dichloro{[2-(4-isobutyloxazol-2-yl)phenyl]diphenylphos­phine-N,P}nickel(II), the Ni—N and Ni—P distances are greater and the N—Ni—P ligand bite angles smaller than those observed in a series of related complexes with square-planar nickel.     

Aquabis(3,5-dimethyl-1H-pyrazole-κN2)(malonato-κ2O,O′)copper(II) ­dihydrate

In the neutral title complex, [Cu(C₃H₂O₄)(C₅H₈N₂)₂(H₂O)]·2H₂O or [Cu(mal)(dmp)₂(H₂O)]·2H₂O (mal is malon­ate and dmp is 3,5-di­methyl-1H-pyrazole), the Cu^II ion, in a slightly distorted square-pyramidal geometry, is coordinated by two O atoms of the bidentate malonate, the O atom of the water ligand and two N atoms from the two 3,5-di­methyl­pyrazole ligands. The mean Cu—N bond length is 2.007 (6) Å, longer than the Cu—O_mal bonds [1.950 (5) Å]. The apical position is occupied by a relatively strongly coordinated water mol­ecule [Cu—O_water 2.288 (5) Å]. The crystal structure is characterized by the layer motif of a hydrogen-bonded network.     

Room-temperature monoclinic and low-temperature triclinic phase-transition structures of meso-octa­methyl­calix­[4]­pyrrole–di­methyl sulfoxide (1/1)

Crystals of the title complex, C₂₈H₃₆N₄·C₂H₆OS, undergo a phase transition between room temperature and 198 K, as determined by X-ray diffraction techniques. A monoclinic form is observed at room temperature, while a triclinic modification is found at 198 K, with Z′ changing from 1 to 2. Differential scanning calorimetry (DSC) of the calix­pyrrole–di­methyl sulfoxide complex revealed a series of phase changes between 273 and 243 K. The transition from the room-temperature monoclinic form to the low-temperature triclinic form is reversible, as determined by changes in the cell dimensions from remeasuring selected reflections at room temperature and at temperatures below 223 K. The uncomplexed calix­[4]­pyrrole mol­ecule shows no phase changes occurring between room temperature and 233 K, the low-temperature limit of the DSC.     

[Phthalocyaninato(2–)]­antimony(III) chloride

The title antimony(III) complex, [Sb(C₃₂H₁₆N₈)]Cl or [SbPc]Cl (where Pc = C₃₂H₁₆N₈²⁻), has been obtained from the reaction of pure powdered antimony with 1,2-di­cyano­benzene under a stream of ICl vapour. The asymmetric unit of this complex consists of an [SbPc]⁺ cation and a Cl⁻ anion. The phthalocyaninate residue [SbPc]⁺ is not planar. The Sb atom lies 1.057 (3) Å from the plane defined by the four iso­indole N atoms. A combination of ionic and donor–acceptor interactions links the [SbPc]Cl mol­ecules to form centrosymmetric [(SbPc)Cl]₂ pseudo-dimers in the crystal. The Sb—Cl distances in the pseudo-dimer are not equivalent [3.043 (2) and 3.201 (2) Å]. The pseudo-dimers are weakly linked through Cl⃛H—C_benzo interactions to form a three-dimensional network. As a result of these interactions, the four Sn—N_isoindole bond lengths in the [SbPc]⁺ residue are not equivalent and the symmetry of the Sb—N core is only close to C_s.     

5,6-Bis(2-pyridyl)-2,3-pyrazine­dicarbo­nitrile

The crystal structure of the title compound, C₁₆H₈N₆, contains two independent mol­ecules with no significant difference in their structures. The pyrazine ring makes dihedral angles of 36.7 (2) and 36.5 (3)° with the two pyridine rings in one mol­ecule, and 43.1 (2) and 38.4 (1)° in the other. The dihedral angles between the two pyridine rings are 58.2 (2) and 56.0 (2)°, respectively. The favoured orientation of the pyridine rings is such that their N atoms face each other.     

Pyridinium tetrakis(nitrato-κ2O,O′)(2,2′:6′,2′′-terpyridine-κ3N)cerate(III) pyridine solvate and bis(methanol-κO)tris(nitrato-κ2O,O′)(2,2′:6′,2′′-terpyridine-κ3N)cerium(III)

The title complexes, (C₅H₆N)[Ce(NO₃)₄(C₁₅H₁₁N₃)]·C₅H₅N or (Hpy)­[Ce(NO₃)₄(terpy)]·py, (I) (py is pyridine, C₅H₅N, and terpy is ter­pyridine, C₁₅H₁₁N₃), and [Ce(NO₃)₃­(C₁₅H₁₁N₃)(CH₄O)₂] or [Ce(NO₃)₃(terpy)(OHCH₃)₂], (II), are 11-coordinate. The coordination polyhedron of the Ce atom in (I) is irregular, while that in (II) can be described as an icosahedron with two vertices replaced by one.     

Di­methyl (1R,8R)-1,11,11-tri­methyl-2,3-di­aza­tri­cyclo­[6.2.1.02,6]­undeca-3,5-diene-4,5-di­carboxyl­ate,a chiral mol­ecule with an approximate centrosymmetric crystal structure

The crystal structure of the title compound, C₁₆H₂₂N₂O₄, has two independent chiral mol­ecules related by a pseudo-inversion centre. 14 of the 22 non-H atoms have a centrosymmetric counterpart within a tolerance of 0.17 Å. A search of the Cambridge Structural Database [Spring 2000; Allen & Kennard (1993). Chem. Des. Autom. News, 8 , 1, 31–37] shows at least 10% of the crystal structures reported in the literature with space group P2₁ and Z = 4 to be chiral compounds with a pseudo-P2₁/c packing.     

trans-Bis(2-amino­pyridine-N)bis(O,O′-diiso­propyl di­thio­phosphato-S,S′)nickel(II)

In the title compound, [Ni(C₆H₁₄O₂PS₂)₂(C₅H₆N₂)₂], the coordination around the Ni atom, which lies on a crystallographic centre of symmetry, is octahedral with the S atoms from the di­thio­phosphate ligands occupying the equatorial positions, while the axial positions are occupied by the ring N atoms of the 2-amino­pyridine ligands. The mol­ecules form layers in the bc plane which are stacked in the direction of the a axis.     

Di­chloro­bis(4-methyl­pentan-2-onato-C4,O)­tin(IV) and bis(4-methyl­pentan-2-onato-C4,O)(2-thio­xo-1,3-di­thiole-4,5-di­thiol­ato-S,S′)­tin(IV) at 150 K

The structures of the ketotins determined here, [SnCl₂(C₆H₁₁O)₂] and [Sn(C₃S₅)(C₆H₁₁O)₂], respectively, along with that previously reported for [MeC(O)CH₂CMe₂]₂SnI₂, are compared with the structures of the analogous estertins [MeOC(O)CH₂CH₂]₂SnX₂. Pairwise comparison of the mean ketotin [estertin] Sn—X and Sn—O distances as Sn—X 2.4422 (4) [2.4054 (7) Å], 2.4970 (4) [2.471 (2) Å] and 2.8463 (4) [2.7788 (8) Å] and Sn—O 2.4926 (12) [2.528 (1) Å], 2.6110 (11) [2.629 (7) Å] and 2.435 (3) [2.525 (4) Å] (for X = Cl, S and I, respectively) clearly demonstrates the superior donor ability of the ketotin O atom in chelate formation.     

Spin crossover studies in tris(N,N′-dialkyldithiocarbamato)iron(III) complexes

A series of fifteen complexes of the type [Fe(RRNCS₂)₃] with symmetric (R=R=n- C₆H₁₃, n-C₈H₁₇, CH₂–CH=;CH₂, C₆H₅, C₆H₁₁ and C₆H₅CH₂), unsymmetric (R = CH₃; R = n-C₄H₉, C₆H₁₁, C₆H₅ and R = C₂H₅; R = n-C₄H₉, C₆H₁₁, C₆H₅ and i-C₃H₇) and ring substituents (RNR=pyrrolidyl and piperidyl) have been synthesized and their magnetic moments and Mössbauer spectra recorded from room temperature (RT) to liquid nitrogen temperature (LNT). Room temperature Mössbauer spectra of all the complexes exhibit an asymmetric doublet, which could be resolved into two doublets, each corresponding to low and high spin states in equilibrium. The crystal structure of tris(N, N-diallyldithiocarbamato)iron(III) shows it to be monoclinic with trigonally distorted octahedral geometry and space group C2/c. Fe–S stretching vibrations in the far i.r. region also show equilibria, HS LS. Depending on the nature of the alkyl group substituent, variable temperature magnetic moment and Mössbauer spectral studies, all the complexes may be divided into three groups; high spin complexes exhibiting spin-crossover (⁶A_1g ²T_2g), high spin complexes exhibiting spin transition (⁶A_1g ⁴T_1g) and intermediate spin complexes showing spin transition (⁴A_1g ²T_2g). On the basis of areas of the two doublets corresponding to high and low spin states, their percent contributions were calculated. Furthermore, magnetic moments of the equilibrium mixture calculated on the basis of respective areas compare well with the experimentally determined _eff values. E_Q values for both high and low spin states show linear decrease with increasing temperature.     

Reduction of carbon dioxide by tris(2,2′-bipyridine)cobalt(I)

Preliminary stoichiometric and kinetic results bearing on the mechanism of the reduction of HCO₃⁻ to CO by tris(2,2′-bipyridine)cobalt(I) in aqueous media are reported. The results indicate that CO (not formate) is the dominant carbon product and that it is scavenged by Co(bpy)₃⁺ to give insoluble [Co(bpy)(CO)₂]₂. At pH ∼ 9, bicarbonate reduction occurs in competition with H₂O reduction. Both processes are inhibited by bpy and promoted by H⁺, suggesting the common intermediate Co(bpy)₂(H₂O)H²⁺. The bicarbonate reaction itself branches to give H₂ and CO in ∼ 3:1 ratio.     

Silver(I) perchlorate complexes of N,N ′-bis(trans-cinnamaldehyde)ethylenediimine (ca2en)

Three silver(I) complexes, [Ag(ca₂en)(PPh₃)]ClO₄ (1), [Ag(ca₂en)(PPh₃)₂]ClO₄ (2) and [Ag(ca₂en)₂]ClO₄ (3), where ca₂en?=?N,N′-bis(trans-cinnamaldehyde)ethylenediimine, have been synthesized and characterized spectroscopically. The crystal structure of (1) was determined by X-ray diffraction methods. Crystal data for 1: C₃₈H₃₅AgClN₂O₄P, triclinic, P 1, a?=?12.086(2), b?=?18.204(2), c?=?8.550(2) Å, α?=?102.69(1), β?=?105.85(1), γ?=?91.47(1)°, V?=?1758.0(5) ų, Z?=?2, R(F)?=?0.070, wR (F)?=?0.064, T?=?296?K. The coordination geometry of the Ag atom is distorted trigonal involving two N atoms of ca₂en and one P atom of triphenylphosphine (PPh₃).     

Bis(O,O′-diiso­propyl di­thio­phosphato-S,S′)(1,10-phenanthroline-N,N′)metal(II) complexes with cadmium(II) and iron(II)

The two title compounds, [M(C₆H₁₄O₂PS₂)₂(C₁₂H₈N₂)], where M = Cd^II and Fe^II, are isomorphous. Each compound has a crystallographic twofold axis of symmetry through the metal atom and the 1,10-phenanthroline mol­ecule. The central metal atom is coordinated to four S atoms from the two dithiophos­phate groups and two N atoms from the 1,10-phenanthroline ligand. The environment of the metal atom is a distorted octahedron.     

Dinuclear rhenium(I) carbonyl complexes based on π-conjugated polypyridyl ligands with tetrathiafulvalenes: Syntheses, crystal structures, properties and DFT calculations

A series of tetrathiafulvalene-substituted 2,3-di(2-pyridyl)quinoxaline (dpq) ligands, 2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-6,7-di(pyridin-2-yl)- [1,3]dithiolo[4,5-g]quinoxaline (L₁), dimethyl-2-(6,7-di(pyridin-2-yl)-[1,3]dithiolo[4,5-g]quinoxalin-2-ylidene)-1,3-dithiole-4,5-dicarboxylate (L₂), and 2-(5,6-dihydro-[1,3]dithiolo[4,5-b] [1,4]dithiin-2-ylidene)-6,7-di(pyridin-2-yl)-[1,3]dithiolo[4,5-g]quinoxaline (L₃), have been prepared. Reactions of these ligands with Re(CO)₅Cl afford the corresponding dinuclear rhenium(I) carbonyl complexes, Re₂(L)(CO)₆Cl₂ (L = L₁, 5a; L = L₂, 5b; L = L₃, 5c). All new compounds are fully characterized by ¹H NMR, IR and mass spectroscopies. The crystal structures of 5a and 5b have been studied. Optimized conformations and molecular orbital diagrams of 5a−5c have been calculated with density functional theory (DFT). The spin-allowed singlet−singlet electronic transitions of all complexes have been calculated with time-dependent DFT (TDDFT), and the UV-Vis−NIR spectra are discussed based on the theoretical calculations.     

Synthesis and characterization of chloro-bis(quinoline-2-carboxylato-κ2N,O)gallium(III)

The preparation and characterization of a new gallium(III) complex with quinoline-2-carboxylate, of formula [Ga(quin-2-c)₂Cl], are described. The crystal structure of the complex has been determined by X-ray diffraction, crystallizing in monoclinic space group P2₁/n with Ga(III) adopting a distorted tetragonal pyramid. Gallium(III) coordinates two quinoline-2-carboxylates and one chloride with a Cl,N₂,O₂ donor set. In the crystal the 2-D supramolecular structure is generated by weak intermolecular interactions, C–H?···?O, C–H?···?Cl, and C–H?···?π. The cytotoxicity assays against several human cancer cell lines (Du145, A549, MCF-7, A498, HT-29) and against mouse fibroblasts (BALB/3T3) revealed moderate antiproliferative activity of the complex.     

STRUCTURES OF COPPER(I) AND ZINC(II) COMPLEXES WITH N,N′-BIS(2-PYRIDINYL)THIOUREA (BPT)

Abstract

Copper(I) and zinc(II) complexes with N,N′-bis(2-pyridinyl)thiourea (BPT), [Cu(BPT)₂]ClO₄ (1) and [Zn(BPT)₂](ClO₄)₂ (2) were synthesized by reaction of M(ClO₄)₂ (M = Cu, Zn) with BPT in methanol solution. The crystal structures of complexes (1) and (2) were characterized by X-ray diffraction: (1) is triclinic, space group P, with a = 10.162(2), b=14.483(6), c = 9.496(2) Å, α = 105.80(2)°, β = 106.94(2)°, γ = 82.71(3)°, V = 1284.4(7) ų, Z = 2, and final R = 0.047, R _w = 0.061; (2) is monoclinic, space group C2/c, with a = 15.15(1), b = 6.299(3), c = 30.16(1)Å, β = 93.49(7)°, V = 2872(2)ų, Z=4, and final R = 0.049, R_w = 0.070. Both of the complexes exhibit novel structures. Two N atoms and two S atoms from two BPT groups coordinate to one M atom. The M atom shows distorted tetrahedral geometry. IR spectra and ther-moanalyses of BPT and its complexes (1) and (2) are briefly discussed.