Platinum(II) Mixed Ligand Complexes with Thiourea Derivatives,Dimethyl Sulphoxide and Chloride: Syntheses,Molecular Structures,and ESCA Data

The platinum(II) mixed ligand complexes [PtCl(L^1‐6)(dmso)] with six differently substituted thiourea derivatives HL, R₂NC(S)NHC(O)R′ (R = Et, R′ = p‐O₂N‐Ph: HL¹; R = Ph, R′ = p‐O₂N‐Ph: HL²; R = R′ = Ph: HL³; R = Et, R′ = o‐Cl‐Ph: HL⁴; R₂N = EtOC(O)N(CH₂CH₂)₂N, R′ = Ph: HL⁵) and Et₂NC(S)N=CNH‐1‐Naph (HL⁶), as well as the bis(benzoylthioureato‐κO, κS)‐platinum(II) complexes [Pt(L^{1, 2})₂] have been synthesized and characterized by elemental analysis, IR, FAB(+)‐MS, ¹H‐NMR, ¹³C‐NMR, as well as X‐ray structure analysis ([PtCl(L¹)(dmso)] and [PtCl(L^{3, 4})(dmso)]) and ESCA ([PtCl(L^{1, 2})(dmso)] and [Pt(L^{1, 2})₂]). The mixed ligand complexes [PtCl(L)(dmso)] have a nearly square‐planar coordination at the platinum atoms. After deprotonation, the thiourea derivatives coordinate bidentately via O and S, DMSO bonds monodentately to the Pt^II atom via S atom in a cis arrangement with respect to the thiocarbonyl sulphur atom. The Pt—S‐bonds to the DMSO are significant shorter than those to the thiocarbonyl‐S atom. In comparison with the unsubstituted case, electron withdrawing substituents at the phenyl group of the benzoyl moiety of the thioureate (p‐NO₂, o‐Cl) cause a significant elongation of the Pt—S(dmso)‐bond trans arranged to the benzoyl‐O—Pt‐bond. The ESCA data confirm the found coordination and bonding conditions. The Pt 4f_7/2 electron binding energies of the complexes [PtCl(L^{1, 2})(dmso)] are higher than those of the bis(benzoylthioureato)‐complexes [Pt(L^{1, 2})₂]. This may indicate a withdrawal of electron density from platinum(II) caused by the DMSO ligands.     

Kinetic Studies of Oxidative Addition Reaction of Arylplatinum(II) Complex Containing 4,4′‐Bipyridine and Calculation of Activation Parameters

New complexes of arylplatinum(II) and arylplatinum(IV) containing a bridging ligand, 4,4′‐bipyridine, were synthesized by the reaction of starting material of platinum(II) including para‐tolyl groups,[(p‐MeC₆H₄)₂Pt(SMe₂)₂], with the 4,4′‐bipyridine ligand in 1:1 molar stoichiometry. In the synthesized complexes, the ligand was bonded to the platinum center through the nitrogen donor atoms. To investigate the kinetic reaction of the platinum(II) complex with iodomethane (CH₃‐I) as a reagent, the oxidative addition reaction of this reagent with Pt(II) was performed in dichloromethane and a Pt(IV) complex with the octahedral geometry was formed. The synthesized complexes have been characterized by different spectroscopic methods such as FT‐IR, ¹H NMR, UV–vis, and elemental analysis. Moreover, the conductivity measurements showed nonelectrolyte characteristics for these complexes. The obtained data showed that the complexes have 1:1 metal‐to‐ligand molar ratio. Also, the oxidative addition reaction of CH₃I with the arylplatinum(II) complex at different temperatures was used for obtaining kinetic parameters such as rate constants, activation energy, entropy, and enthalpy of activation using the Microsoft Excel solver. From the acquired data, an S_N2 mechanism was suggested for the oxidative addition reaction.     

Synthesis,Structural Characterization and Reactivity of a Bis(phosphine)(silyl) Platinum(II) Complex

Treatment of 1,2‐C₆H₄(SiH₃)(SiH₃) ( 1 ) with Pt(dmpe)(PEt₃)₂ (dmpe=Me₂PCH₂CH₂PMe₂) in the ratio of 1:1 leads to the complex {1,2‐C₆H₄(SiH₂)(SiH₂)}Pt^II (dmpe) ( 2 ), which can react with proton organic reagent bearing hydroxy group with low steric hindrance to form a tetra‐alkoxy substituted silyl platinum(II) compound ( 3 ). Compounds 2 and 3 are the very rare examples of silyl transition‐metal complexes derived from this chelating hydrosilane ligand. To the best of our knowledge, there are only 6 examples of silyl metal complexes prepared from this ligand with such structural features registered in the Cambridge Structural Database, among them, only one silyl platinum(II) compound is presented. The structures of complexes 2 and 3 were unambiguously determined by multinuclear NMR spectroscopic studies and single crystal X‐ray analysis.     

Hydrogen‐bonded chains in three cis‐dichloridoplatinum(II) complexes bearing piperidine and amine ligands

The crystal structures of cis‐dichlorido(ethylamine‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₂H₇N)(C₅H₁₁N)], (I), cis‐dichlorido(3‐methoxyaniline‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₇H₉NO)], (II), and cis‐dichlorido(piperidine‐κN)(quinoline‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₉H₇N)], (III), have been determined at 100 K in order to verify the influence of the nonpiperidine ligand on the geometry and crystal packing. The crystal packing is characterized by N—H...Cl hydrogen bonding, resulting in the formation of chains of molecules connected in a head‐to‐tail fashion. Hydrogen‐bonding interactions play a major role in the packing of (I), where the chains further aggregate into planes, but less so in the case of (II) and (III), where π–π stacking interactions are of greater importance.     

Pseudohalide‐directed Assembly of Two Zinc(II) Coordination Polymers with a 3,4‐Bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole Tecton

The zinc(II) pseudohalide complexes {[Zn(L³³⁴)(SCN)₂(H₂O)](H₂O)₂}_n ( 1 ) and [Zn(L³³⁴)(dca)₂]_n ( 2 ) were synthesized and characterized using the ligand 3,4‐bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole (L³³⁴) and ZnCl₂ in presence of thiocyanate (SCN^–) and dicynamide [dca, N(CN)₂^–] respectively. Single‐crystal X‐ray structural analysis revealed that the central Zn^II atoms in both complexes have similar octahedral arrangement. Compound 1 has a 2D sheet structure bridged by bidentate L³³⁴ and double μ_N,S‐thiocyanate anions, whereas complex 2 , incorporating with two monodentate dicynamide anions, displays a two‐dimensional coordination framework bridged by tetradentate L³³⁴ ligand. Structural analysis demonstrated that the influence of pseudohalide anions plays an important role in determining the resultant structure. Both complexes were characterized by IR spectroscopy, microanalysis, and powder X‐ray diffraction techniques. In addition, the solid fluorescence and thermal stability properties of both complexes were investigated.     

Synthesis and Structural Characterization of Some Potassium Complexes of Some Bis(phenolate) Ligands and Some Novel Heterobimetallic Binuclear Arrays Formed with Trivalent Lanthanoid Ions

The structural characterizations of the potassium complexes of a pair of dianionic bis(phenolate) ligands, {L^R = [^?OC₆H₂(2,4‐Bu^t)(6‐CH₂)]₂NCH₂CH₂R} R = NMe₂, OMe, crystallized from 1,2,‐dimethoxyethane (DME) are recorded, showing them to take the binuclear form [K₂L^R(DME)₃]. A pair of neutral binuclear heterobimetallic isotypic complexes are defined with ytterbium(III), with phenol, as sodium salts, of the form [Yb(L^R)(OPh)₂Na(DME)(HOPh)], and a further array with samarium(III), of the (partially protonated) form [Sm(L^OMe)₂Na(OH₂)]. A further complex, [Na(DME)₃][Yb(*L^py)₂], results from an unusual ligand reduction by an ytterbium(II) species to give a new dianionic Schiff base ligand which is coordinated to ytterbium(III) {*L^py = ^?OC₆H₂(2,4‐Bu^t)(6‐CH=N‐CH‐2‐C₆H₄N)}.     

Heteronuclear complexes of oxorhenium(V) with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO2(VI) and their biological activities

Heteronuclear complexes containing oxorhenium(V), with Fe(III), Co(II), Ni(II), Cu(II), Cd(II) and UO₂(VI) ions were prepared by the reaction of the complex ligands [ReO(HL¹)(PPh₃)(OH₂)Cl]Cl (a) and/or [ReO(H₂L²)(PPh₃)(OH₂)Cl]Cl (b), where H₂L¹?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(5,6-diphenyl-1,2,4-triazine-3-ylhydrazone) and H₃L²?=?1-(2-hydroxyphenyl)butane-1,3-dione-3-(1H-benzimidazol-2-ylhydrazone), with transition and actinide salts. Heterodinuclear complexes of ReO(V) with Fe(III), Co(II), Ni(II), Cu(II) and Cd(II) were obtained using a 1?:?1 mole ratio of the complex ligand and the metal salt. Heterotrinuclear complexes were obtained containing ReO(V) with UO₂(VI) and Cu(II) using 2?:?1 mole ratios of the complex ligand and the metal salts. The complex ligands a and b coordinate with the heterometal ion via a nitrogen of the heterocyclic ring and the nitrogen atom of the C=N⁷ group. All transition metal cations in the heteronuclear complexes have octahedral configurations, while UO₂(VI)?complexes have distorted dodecahedral geometry. The structures of the complexes were elucidated by IR, ESR, electronic and ¹H NMR spectra, magnetic moments, conductance and TG-DSC measurements. The antifungal activities of the complex ligands and their heteronuclear complexes towards Alternaria alternata and Aspergillus niger showed comparable behavior with some well-known antibiotics.     

Synthesis,characterization, and biological and anticancer studies of mixed ligand complexes with Schiff base and 2,2′‐bipyridine

New mixed ligand complexes of transition metals were synthesized from a Schiff base (L¹) obtained by the condensation reaction of oxamide and furfural as primary ligand and 2,2′‐bipyridine (L²) as secondary ligand. The ligands and their metal complexes were studied using various spectroscopic methods. Also thermal analyses were conducted. The mixed ligand complexes were found to have formulae [M(L¹)(L²)]Cl_m ⋅n H₂O (M = Cr(III) and Fe(III): m  = 3, n  = 0; M = Cu(II) and Cd(II): m  = 2, n  = 1; M = Mn(II), Co(II), Ni(II) and Zn(II): m  = 2, n  = 0). The resultant data revealed that the metal complexes have octahedral structure. Also, the mixed ligand complexes are electrolytic. The biological and anticancer activities of the new compounds were tested against breast cancer (MCF‐7) and colon cancer (HCT‐116) cell lines. The results showed high activity for the synthesized compounds.     

Toxicology and antitumour activity of ferrocenylamines and platinum derivatives

Toxicity, antitumour, platinum distribution, hepatotoxicity and histology data are presented for a series of ferrocenylamines: [(η‐C₅H₄(CH₂)_nNH₂)FeCp] (n = 0,1) ( 1 , 2 ); [(η‐C₅H₄CH₂NHPh)FeCp] ( 3 ); [(η‐C₅H₄CH₂NMe₂)FeCp] ( 4 ); {[η‐C₅H₄CH(Me)NMe₂]FeCp} ( 5 ); [η‐C₅H₄CH₂NMe₂)₂Fe] ( 6 ); {[1,2η‐C₅H₃(CHMeNMe₂)(PPh₂)]FeCp} ( 7 ); {[1,2η‐C₅H₃(CHMeNMe₂)(PPh₂)]Fe[η‐C₅H₄PPh₂]} ( 8 ); and their complexes cis‐PtCl₂L₂ ( 9 ); trans ‐ Pt(L)(dmso)X₂ ( 10 ); [σ ‐ (L)Pt(dmso)X] ( 11 , 12 ) {σ‐(L)[Pt(dmso)X]₂} ( 13 ); [σ‐(L)PtP(OPh)₃Cl] ( 14 ) (L = ferrocenylamine). The toxicity order is 1 – 3 ≫ 4 – 8 for the ferrocenylamines; the lower toxicity of tertiary amines may be due to protonation in vivo. Pt(II) complexes all show increased toxicity over the ligand. Liver, not kidney, damage is the norm from i.p. injection of 1 – 14 and detailed platinum distribution, blood serum and histology studies with 9 and 11 show that the platinum distribution does not correlate with liver dysfunction. Complexes 9 – 14 , but not 1 – 8 , were active against P‐388 mouse leukaemia tumour and cisplatin‐resistant sarcoma, but inactive against L‐1210 mouse leukaemia and B‐16 melanoma. Copyright © 1999 John Wiley & Sons, Ltd.     

Structural and spectroscopic characterization of two new blue luminescent pyridylbenzimidazole zinc(II) complexes

Luminescent metal complexes are used in photooptical devices. Zinc(II) complexes are of interest because of the ability to tune their color, their high thermal stability and their favorable carrier transport character. In particular, some zinc(II) complexes with aryl diimine and/or heterocyclic ligands have been shown to emit brightly in the blue region of the spectrum. Zinc(II) complexes bearing derivatized imidazoles have been explored for possible optoelectronic applications. The structures of two zinc(II) complexes of 5,6‐dimethyl‐2‐(pyridin‐2‐yl)‐1‐[(pyridin‐2‐yl)methyl]‐1H‐benzimidazole (L), namely dichlorido(dimethylformamide‐κO){5,6‐dimethyl‐2‐(pyridin‐2‐yl‐κN)‐1‐[(pyridin‐2‐yl)methyl]‐1H‐benzimidazole‐κN³}zinc(II) dimethylformamide monosolvate, [ZnCl₂(C₂₀H₁₈N₄)(C₃H₇NO)]·C₃H₇NO, (I), and bis(acetato‐κ²O,O′){5,6‐dimethyl‐2‐(pyridin‐2‐yl‐κN)‐1‐[(pyridin‐2‐yl)methyl]‐1H‐benzimidazole‐κN³}zinc(II) ethanol monosolvate, [Zn(C₂H₃O₂)₂(C₂₀H₁₈N₄)]·C₂H₅OH, (II), are reported. Complex (I) crystallized as a dimethylformamide solvate and exhibits a distorted trigonal bipyramidal coordination geometry. The coordination sphere consists of a bidentate L ligand spanning axial to equatorial sites, two chloride ligands in equatorial sites, and an O‐bound dimethylformamide ligand in the remaining axial site. The other complex, (II), crystallized as an ethanol solvate. The Zn^II atom has a distorted trigonal prismatic coordination geometry, with two bidentate acetate ligands occupying two edges and a bidentate L ligand occupying the third edge of the prism. Complexes (I) and (II) emit in the blue region of the spectrum. The results of density functional theory (DFT) calculations suggest that the luminescence of L results from π*←π transitions and that the luminescence of the complexes results from interligand charge‐transfer transitions. The orientation of the 2‐(pyridin‐2‐yl) substituent with respect to the benzimidazole system was found to have an impact on the calculated HOMO–LUMO gap (HOMO is highest occupied molecular orbital and LUMO is lowest unoccupied molecular orbital).     

Synthesis and crystal structure of an M4L6 tetrahedral cage with outward‐facing pockets from a substituted pyrazolyl–pyridine ligand

The self‐assembly of metal–polydentate ligands to give supramolecular tetrahedral complexes is of considerable current interest. A new ligand, 4‐benzyl‐2‐[1‐(2‐{[3‐(4‐benzylpyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]methyl}benzyl)‐1H‐pyrazol‐3‐yl]pyridine (L), with chelating pyrazolyl–pyridine units substituted on the 4‐position of the pyridyl ring with benzyl units, has been synthesized and fully characterized. The self‐assembly of L with cobalt(II) gave rise to a tetrahedral cage (hexakis{μ‐4‐benzyl‐2‐[1‐(2‐{[3‐(4‐benzylpyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]methyl}benzyl)‐1H‐pyrazol‐3‐yl]pyridine}perchloratotetracobalt(II) octakis(perchlorate) acetonitrile undecasolvate, [Co₄(ClO₄)(C₃₈H₃₂N₆)₆](ClO₄)₇·11CH₃CN) with approximate T symmetry. The X‐ray crystal structure of the cage, i.e. [Co₄L₆ClO₄](ClO₄)₇, shows that the substituted benzyl groups are oriented away from the centres of their respective ligands towards the Co^II vertices, making small outward‐facing pockets from three benzyl rings at the corners of the tetrahedron.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.     

Syntheses and Structures of Nitridorhenium(V) and Nitridotechnetium(V) Complexes with N,N‐[(Dialkylamino)(thiocarbonyl)]‐N′‐(2‐hydroxyphenyl)benzamidines

[MNCl₂(PPh₃)₂] complexes (M = Re, Tc) react with N‐[(dialkylamino)(thiocarbonyl)]‐N′‐(2‐hydroxyphenyl)benzamidines (H₂L¹) with formation of neutral, five‐coordinate nitrido complexes of the composition [MN(L¹)(PPh₃)]. The products have distorted square‐pyramidal coordination spheres with each a tridentate, double‐deprotonated benzamidine and a PPh₃ ligand in their basal planes.     

Killing two birds with one stone: 2D+2D→3D parallel stacking and 3D self‐penetrating structures in one reaction and their crystal‐to‐crystal transformation

Reaction of the flexible phenolic carboxylate ligand 2‐(3,5‐dicarboxylbenzyloxy)benzoic acid (H₃L) with nickel salts in the presence of 1,2‐bis(pyridin‐4‐yl)ethylene (bpe) leads to the generation of a mixture of the two complexes under solvolthermal conditions, namely poly[[aqua[μ‐1,2‐bis(pyridin‐4‐yl)ethylene‐κ²N:N′]{μ‐5‐[(2‐carboxyphenoxy)methyl]benzene‐1,3‐dicarboxylato‐κ³O¹,O^1′:O³}nickel(II)] dimethylformamide hemisolvate monohydrate], {[Ni(C₁₆H₁₀O₇)(C₁₂H₁₀N₂)(H₂O)]·0.5C₃H₇NO·H₂O}_n or {[Ni(HL)(bpe)(H₂O)]·0.5DMF·H₂O}_n, 1 , and poly[[diaquatris[μ‐1,2‐bis(pyridin‐4‐yl)ethylene‐κ²N:N′]bis{μ‐5‐[(2‐carboxyphenoxy)methyl]benzene‐1,3‐dicarboxylato‐κ²O¹:O⁵}nickel(II)] dimethylformamide disolvate hexahydrate], {[Ni₂(C₁₆H₁₀O₇)₂(C₁₂H₁₀N₂)₃(H₂O)₂]·2C₃H₇NO·6H₂O}_n or {[Ni₂(HL)₂(bpe)₃(H₂O)₂]·2DMF·6H₂O}_n, 2 . In complex 1 , the Ni^II centres are connected by the carboxylate and bpe ligands to form two‐dimensional (2D) 4‐connected (4,4) layers, which are extended into a 2D+2D→3D (3D is three‐dimensional) supramolecular framework. In complex 2 , bpe ligands connect to Ni^II centres to form 2D layers with Ni₆(bpe)₆ metallmacrocycles. Interestingly, 2D+2D→3D inclined polycatenation was observed between these layers. The final 5‐connected 3D self‐penetrating structure was generated through further connection of Ni–carboxylate chains with these inclined motifs. Both complexes were fully characterized by single‐crystal analysis, powder X‐ray diffraction analysis, FT–IR spectra, elemental analyses, thermal analysis and UV–Vis spectra. Notably, an interesting metal/ligand‐induced crystal‐to‐crystal transformation was observed between the two complexes.     

The trans influence of the pyridine ligand on ruthenium(II)–porphyrin–carbene complexes

In the two ruthenium(II)–porphyrin–carbene complexes ­(di­benzoyl­carbenyl‐κC)(pyridine‐κN)(5,10,15,20‐tetra‐p‐tolyl­porphyrinato‐κ⁴N)­ruthenium(II), [Ru(C₁₅H₁₀O₂)(C₅H₅N)(C₄₈H₃₆N₄)], (I), and (pyridine‐κN)(5,10,15,20‐tetra‐p‐tolyl­porphyrinato‐κ⁴N)[bis(3‐tri­fluoro­methyl­phenyl)­carbenyl‐κC]­ruthenium(II), [Ru(C₁₅H₈F₆)(C₅H₅N)(C₄₈H₃₆N₄)], (II), the pyridine ligand coordinates to the octahedral Ru atom trans with respect to the carbene ligand. The C(carbene)—Ru—N(pyridine) bonds in (I) coincide with a crystallographic twofold axis. The Ru—C bond lengths of 1.877 (8) and 1.868 (3) Å in (I) and (II), respectively, are slightly longer than those of other ruthenium(II)–porphyrin–carbene complexes, owing to the trans influence of the pyridine ligands.     

Synthesis,Crystal Structures,and Properties of Copper(II), Zinc(II), and Cadmium(II) Coordination Polymers Based on 5‐Nitro‐isophthalate and 1,2‐(2‐Pyridyl)‐1,2,4‐triazole

Three coordination polymers, namely {[Cu(5‐nipa)(L²²)](H₂O)₂}_n ( 1 ), [Zn(5‐nipa)(L²²)(H₂O)]_n ( 2 ), and {[Cd₂(5‐nipa)₂(L²²)(H₂O)₃](H₂O)_3.6}_n ( 3 ), were prepared under similar synthetic method based on 1,2‐(2‐pyridyl)‐1,2,4‐triazole (L²²) and ancillary ligand 5‐nitro‐isophthalic acid (5‐H₂nipa) with Cu^II, Zn^II, and Cd^II perchlorate, respectively. All the complexes were characterized by IR spectroscopy, elemental analysis, and powder X‐ray diffraction (PXRD) patterns. Single‐crystal X‐ray diffraction indicates that complexes 1 and 2 show similar 1D chain structures, whereas complex 3 exhibits the 2D coordination network with hcb topology. The central metal atoms show distinct coordination arrangements ranging from distorted square‐pyramid for Cu^II in 1 , octahedron for Zn^II in 2 , to pentagonal‐bipyramid for Cd^II in 3 . The L²² ligand adopts the same (η³,μ₂) coordination fashion in complexes 1 – 3 , while the carboxyl groups of co‐ligand 5‐nipa^2– adopt monodentate fashion in 1 and 2 and bidentate chelating mode in 3 . These results indicate that the choice of metal ions exerts a significant influence on governing the target complexes. Furthermore, thermal stabilities of complexes 1 – 3 and photoluminescent properties of 2 and 3 were also studied in the solid state.     

Four NiII complexes with the new cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane

Although it has not proved possible to crystallize the newly prepared cyclam–methylimidazole ligand 1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane (L^Im1), the trans and cis isomers of an Ni^II complex, namely trans‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) monohydrate, [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂·H₂O, (1), and cis‐aqua{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate), [Ni(C₁₅H₃₀N₆)(H₂O)](ClO₄)₂, (2), have been prepared and structurally characterized. At different stages of the crystallization and thermal treatment from which (1) and (2) were obtained, a further two compounds were isolated in crystalline form and their structures also analysed, namely trans‐{1‐[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}(perchlorato)nickel(II) perchlorate, [Ni(ClO₄)(C₁₅H₃₀N₆)]ClO₄, (3), and cis‐{1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane}nickel(II) bis(perchlorate) 0.24‐hydrate, [Ni(C₂₀H₃₆N₆)](ClO₄)₂·0.24H₂O, (4); the 1,8‐bis[(1‐methyl‐1H‐imidazol‐2‐yl)methyl]‐1,4,8,11‐tetraazacyclotetradecane ligand is a minor side product, probably formed in trace amounts in the synthesis of L^Im1. The configurations of the cyclam macrocycles in the complexes have been analysed and the structures are compared with analogues from the literature.     

Synthesis,spectral characterization,electrochemistry and catalytic activities of Cu(II) complexes of bifunctional tridentate Schiff bases containing O?N?O donors

Paramagnetic copper(II) complexes of the type [Cu(PPh₃)(L)] (where L = bifunctional tridentate Schiff bases) were synthesized from the reaction of anthranillic acid with salicylaldehyde (H₂L¹), 2‐hydroxy‐1‐naphthaldehyde (H₂L²), o‐hydroxyacetophenone (H₂L³) and o‐vanillin (H₂L⁴) with monomeric metal precursor [CuCl₂(PPh₃)₂]. The obtained complexes were characterized by elemental analysis, magnetic susceptility and spectroscopic methods (FT‐IR, UV–vis and EPR and cyclic voltammetry). EPR and redox potential studies have been carried out to elucidate the electronic structure, nature of metal–ligand bonding and electrochemical features. EPR spectra exhibit a four line pattern with nitrogen super‐hyperfine couplings originating from imine nitrogen atom. These planar complexes possess a significant amount of tetrahedral distortion leading to a pseudo‐square planar geometry, as is evidenced from EPR properties. Cyclic voltammograms of all the complexes display quasireversible oxidations, Cu(III)? Cu(II), in the range 0.31–0.45 V and reduction peaks, Cu(II)? Cu(I),in the range ?0.29 to ?0.36 V, involving a large geometrical change and irreversible. The observed redox potentials vary with respect to the size of the chelate ring of the Schiff base ligands. Further, the catalytic activity of all the complexes has been found to be high towards the oxidation of alcohols into aldehydes and ketones in the presence of N‐methylmorpholine‐N‐oxide as co‐oxidant. The formation of high valent Cu^IV?O oxo species as a catalytic intermediate is proposed for the catalytic process. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis,characterization, and biological investigation of new mixed-ligand complexes

A novel series of mixed-ligand complexes of 5,5′-{(1E,1E′)-1,4-phenelynebis(diazene-2,1-diyl)}bis(quinolin-8-ol) (H₂L₁) as a primary ligand and 4-aminoantipyrine(L₂) as a secondary ligand with Mn(II) ion were prepared using two general formulae: [Mn₂(H₂L₁)₂(L₂)₂X₄].4Cl (X = OH₂( 1 ), ONO₂⁻( 2 ), Cl=nil; OAc( 3 ), Cl = nil) and [Mn₂(H₂L₁)(L₂)₂(O₂SO₂)₂]( 4 ). Free ligands and their complexes were characterized. Electronic absorption spectra of the mixed-ligand complexes indicate a distorted octahedral geometry around the central metal ion, and the anions X⁻ are in the axial positions for all compounds. The ligands behave in a neutral bidentate manner, through nitrogen atoms and oxygen atoms of the carbonyl group (L₂), whereas H₂L₁ coordinated through nitrogen and OH groups as a neutral bidentate ligand. All complexes do not contain coordinated water molecules, but complex ( 1 ) contains four water molecules. The water molecules are removed in a single step. The complexes exhibited magnetic susceptibility corresponding to five unpaired electrons. The antimicrobial activity of the Mn(II) mixed-ligand complexes ( 1–4 ) against two gram-positive bacteria, three local gram-negative bacteria, and three fungi species was tested. Mn(II) mixed-ligand complex ( 2 ) exhibited significant antibacterial activity against Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas sp. Mixed-ligand complex ( 2 ) exhibited a high potential cytotoxicity against the growth of human lung cancer cells.     

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η2‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC1)platinum(II)]

Crystallization experiments with the dinuclear chelate ring complex di‐μ‐chlorido‐bis[(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)platinum(II)], [Pt₂(C₁₅H₁₉O₄)₂Cl₂], containing a derivative of the natural compound eugenol as ligand, have been performed. Using five different sets of crystallization conditions resulted in four different complexes which can be further used as starting compounds for the synthesis of Pt complexes with promising anticancer activities. In the case of vapour diffusion with the binary chloroform–diethyl ether or methylene chloride–diethyl ether systems, no change of the molecular structure was observed. Using evaporation from acetonitrile (at room temperature), dimethylformamide (DMF, at 313 K) or dimethyl sulfoxide (DMSO, at 313 K), however, resulted in the displacement of a chloride ligand by the solvent, giving, respectively, the mononuclear complexes (acetonitrile‐κN)(η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chloridoplatinum(II) monohydrate, [Pt(C₁₅H₁₉O₄)Cl(CH₃CN)]·H₂O, (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethylformamide‐κO)platinum(II), [Pt(C₁₅H₁₉O₄)Cl(C₂H₇NO)], and (η²‐2‐allyl‐4‐methoxy‐5‐{[(propan‐2‐yloxy)carbonyl]methoxy}phenyl‐κC¹)chlorido(dimethyl sulfoxide‐κS)platinum(II), determined as the analogue {η²‐2‐allyl‐4‐methoxy‐5‐[(ethoxycarbonyl)methoxy]phenyl‐κC¹}chlorido(dimethyl sulfoxide‐κS)platinum(II), [Pt(C₁₄H₁₇O₄)Cl(C₂H₆OS)]. The crystal structures confirm that acetonitrile interacts with the Pt^II atom via its N atom, while for DMSO, the S atom is the coordinating atom. For the replacement, the longest of the two Pt—Cl bonds is cleaved, leading to a cis position of the solvent ligand with respect to the allyl group. The crystal packing of the complexes is characterized by dimer formation via C—H…O and C—H…π interactions, but no π–π interactions are observed despite the presence of the aromatic ring.