Novel octahedral nickel(II) dithiocarbamates with bi- or tetradentate N-donor ligands: X-ray structures of [Ni(Bzppzdtc)(phen)2]ClO4 · CHCl3 and [Ni(Bz2dtc)2(cyclam)]

A series of novel octahedral nickel(II) dithiocarbamate complexes involving bidentate nitrogen-donor ligands (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) or a tetradentate ligand (cyclam = 1,4,8,11-tetraazacycloteradecane) of the composition [Ni(BzMetdtc)(phen)₂]ClO₄ (1), [Ni(Pe₂dtc)(phen)₂]ClO₄ (2), [Ni(Bzppzdtc)(phen)₂]ClO₄ · CHCl₃ (3), [Ni(Bzppzdtc)(phen)₂](SCN) (4), [Ni(BzMetdtc)(bpy)₂]ClO₄ · 2H₂O (5), [Ni(Pe₂dtc)(cyclam)]ClO₄ (6), [Ni(BzMetdtc)₂(cyclam)] (7), [Ni(Bz₂dtc)₂(cyclam)] (8) and [Ni(Bz₂dtc)₂(phen)] (9) (BzMetdtc = N,N-benzyl-methyldithiocarbamate(1-) anion, Pe₂dtc = N,N-dipentyldithiocarbamate(1-) anion, Bz₂dtc = N,N-dibenzyldithiocarbamate(1-) anion, Bzppzdtc = 4-benzylpiperazinedithiocarbamate(1-) anion), have been synthesized. Spectroscopic (electronic and infrared), magnetic moment and molar conductivity data, and thermal behaviour of the complexes are discussed. Single crystal X-ray analysis of 3 and 8 confirmed a distorted octahedral arrangement in the vicinity of the nickel atom with a N₄S₂ donor set. They represent the first X-ray structures of such type complexes. The catalytic influence of complexes 2, 3, 6, and 7 on graphite oxidation was studied and discussed.     

Synthesis,structure and properties of some copper(II) complexes containing an ONO donor Schiff base and substituted imidazole ligands

Five new mixed ligand coper(II) complexes, viz. [Cu(SAA)(H₂O)] (1), [Cu(SAA)(MeImH)] (2), [Cu(SAA)(EtImH)] (3), [Cu(SAA)(BenzImH)] (4) and [Cu(SAA)(MebenzImH)] (5), where SAA = salicylideneanthranilic acid, MeImH = 2-methylimidazole, EtImH = 2-ethylimidazole, BenzImH = benzimidazole, MebenzImH = 2-methylbenzimidazole, have been synthesized and characterized by means of elemental analysis, FAB mass spectrometry, magnetic susceptibility, X-band EPR, electronic spectroscopy, IR and cyclic voltammetry. The frozen solution EPR spectra of the complexes have shown axial features. Single crystal X-ray analysis of 2 and 3 has revealed the presence of a distorted square planar geometry (N₂O₂) in the complexes. The superoxide dismutase (SOD) activity of the present complexes has also been measured and discussed.     

Synthesis,crystal structures and magnetic properties of three Ni(II) complexes having NiN4 core with argentocyanide,terephthalate and dicyanamide ions: From discrete molecule to a helical network

This work describes the synthesis and X-ray crystallographic characterization of three nickel(II) complexes [Ni(3,2,3-tet){Ag(CN)₂}₂] (1), [Ni(3,2,3-tet)(μ-tp)]_n · 1.5nH₂O (2) and {[Ni(3,2,3-tet)(μ_1,5-dca)](ClO₄)}_n (3) where 3,2,3-tet = N,N′-bis(3-aminopropyl)-1,2-ethylenediamine, tp = terephthalate and dca = dicyanamide. Compound 1 is a heterotrinuclear discrete distorted octahedral molecule whereas compound 2 forms a 1D polymeric network and an extended 2D network is formed by intermolecular hydrogen bonding. Interestingly, two adjacent 1D chains execute a novel double-helical network constructed by Ni(II) and the bridging dca ligand in compound 3. The variable temperature magnetic susceptibility measurements for compounds 2 and 3 were also carried out.     

Syntheses,crystal structures and magnetic properties of three new binuclear Ni(II) complexes derived from tripodal tetradentate (N4) ligands

Three new binuclear Ni(II) complexes [{Ni(L_22py)Cl}₂](ClO₄)₂ (1), [{Ni(L_23py)Cl}₂](ClO₄)₂ (2), and [{Ni(L_33py)Cl}₂](ClO₄)₂ (3), {L_22py = N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,2-diaminoethane, L_23py = N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,3-diaminopropane, L_33py = N-(2-pyridylmethyl)-N-(3-aminopropyl)-1,3-diaminopropane} have been synthesized. Single crystal X-ray structure analysis showed that in each complex two distorted octahedral Ni(II) ions are bridged asymmetrically by a pair of chloride anions. Variable temperature magnetic susceptibility measurements of 1 and 3 revealed dominant ferromagnetic exchange interactions.     

Complexes derived from the general copper(II)/maleamic acid/N,N′,N′′-chelate reaction systems: Synthetic,reactivity, structural and spectroscopic studies

The synthetic investigation of the Cu^II/maleamate(−1) ion (HL⁻)/N,N′,N′′-chelate general reaction system has allowed access to compounds [Cu₂(HL)₂(bppy)₂](ClO₄)₂·H₂O (1·H₂O), [Cu(HL)(bppy)(ClO₄)] (2) and [Cu(HL)(terpy)(H₂O)](ClO₄) (4) (bppy = 2,6-bis(pyrazol-1-yl)pyridine, terpy = 2,2′;6′,2′′-terpyridine). In the absence of externally added hydroxides, compound [Cu₂(L′)₂(bppy)₂](ClO₄)₂ (3) was obtained from MeOH solutions; L′⁻ is the monomethyl maleate(−1) ligand which is formed in situ via the Cu^II-assisted HL⁻ → L′⁻ transformation. In the case of tptz-containing (tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) reaction systems, the Cu^II-assisted hydrolysis of tptz to pyridine-2-carboxamide (L1) afforded complex [Cu(L1)₂(NO₃)₂] (5). The crystal structures of 1–5 are stabilized by intermolecular hydrogen bonding and π–π stacking interactions. Characteristic IR bands of the complexes are discussed in terms of the known structures and the coordination modes of the ligands.     

Synthesis,structure, and electrochemistry of pyridinecarboxamide cobalt(III) complexes; the effect of bridge substituents on the redox properties

Two series of complexes of the types trans-[Co^III(Mebpb)(amine)₂]ClO₄ {Mebpb²⁻ = N,N-bis(pyridine-2-carboxamido)-4-methylbenzene dianion, and amine = pyrrolidine (prldn) (1a), piperidine (pprdn) (2a), morpholine (mrpln) (3a), benzylamine (bzlan) (4a)}, and trans-[Co^III(cbpb)(amine)₂]X {cbpb²⁻ = N,N-bis(pyridine-2-carboxamido)-4-chlorobenzene dianion, and amine = pyrrolidine (prldn), X = PF₆ (1b), piperidine (pprdn), X = PF₆ (2b), morpholine (mrpln), X = ClO₄ (3b), benzylamine (bzlan), X = PF₆ (4b)} have been synthesized and characterized by elemental analyses, IR, UV–Vis, and ¹H NMR spectroscopy. The crystal structure of 1a has been determined by X-ray diffraction. The electrochemical behavior of these complexes, with the goal of evaluating the effect of axial ligation and equatorial substitution on the redox properties, is also reported. The reduction potential of Co^III, ranging from −0.53 V for (1a) to −0.31 V for (3a) and from −0.48 V for (1b) to −0.22 V for (3b) show a relatively good correlation with the σ-donor ability of the axial ligands. The methyl and chloro substituents of the equatorial ligand have a considerable effect on the redox potentials of the central cobalt ion and the ligand-centered redox processes.     

Coordination compounds of N,N′-olefin functionalized imidazolin-2-ylidenes

N-Heterocyclic carbene ligands (NHC) were metalated with Pd(OAc)₂ or [Ni(CH₃CN)₆](BF₄)₂ by in situ deprotonation of imidazolium salts to give the N-olefin functionalized biscarbene complexes [MX₂(NHC)₂] 3-7 (3: M = Pd, X = Br, NHC = 1,3-di(3-butenyl)imidazolin-2-ylidene; 4: M = Pd, X = Br, NHC = 1,3-di(4-pentenyl)imidazolin-2-ylidene; 5: M = Pd, X = I, NHC = 1,3-diallylimidazolin-2-ylidene; 6: M = Ni, X = I, NHC = 1,3-diallylimidazolin-2-ylidene; 7: M = Ni, X = I, NHC = 1-methyl-3-allylimidazolin-2-ylidene). Molecular structure determinations for 4-7 revealed that square-planar complexes with cis (5) or trans (4, 6, 7) coordination geometry at the metal center had been obtained. Reaction of nickelocene with imidazolium bromides afforded the η⁵-cyclopentadienyl (η⁵-Cp) monocarbene nickel complexes [NiBr(η⁵-Cp)(NHC)] 8 and 9 (8: NHC = 1-methyl-3-allylimidazolin-2-ylidene; 9: NHC = 1,3-diallylimidazolin-2-ylidene). The bromine abstraction in complexes 8 and 9 with silver tetrafluoroborate gave complexes [NiBr(η⁵-Cp)(η³-NHC)] 10 and 11. The X-ray structure analysis of 10 and 11 showed a trigonal-pyramidal coordination geometry at the nickel(II) center and coordination of one N-allyl substituent.     

Nucleophilic substitution reactions at the Si-Cl bonds of the dichloro(methyl)silyl ligand in five- and six-coordinate complexes of ruthenium(II) and osmium(II)

Treatment of either RuHCl(CO)(PPh₃)₃ or MPhCl(CO)(PPh₃)₂ with HSiMeCl₂ produces the five-coordinate dichloro(methyl)silyl complexes, M(SiMeCl₂)Cl(CO)(PPh₃)₂ (1a, M = Ru; 1b, M = Os). 1a and 1b react readily with hydroxide ions and with ethanol to give M(SiMe[OH]₂)Cl(CO)(PPh₃)₂ (2a, M = Ru; 2b, M = Os) and M(SiMe[OEt]₂)Cl(CO)(PPh₃)₂ (3a, M = Ru; 3b, M = Os), respectively. 3b adds CO to form the six-coordinate complex, Os(SiMe[OEt]₂)Cl(CO)₂(PPh₃)₂ (4b) and crystal structure determinations of 3b and 4b reveal very different Os-Si distances in the five-coordinate complex (2.3196(11) Å) and in the six-coordinate complex (2.4901(8) Å). Reaction between 1a and 1b and 8-aminoquinoline results in displacement of a triphenylphosphine ligand and formation of the six-coordinate chelate complexes M(SiMeCl₂)Cl(CO)(PPh₃)(κ²(N,N)-NC₉H₆NH₂-8) (5a, M = Ru; 5b, M = Os), respectively. Crystal structure determination of 5a reveals that the amino function of the chelating 8-aminoquinoline ligand is located adjacent to the reactive Si-Cl bonds of the dichloro(methyl)silyl ligand but no reaction between these functions is observed. However, 5a and 5b react readily with ethanol to give ultimately M(SiMe[OEt]₂)Cl(CO)(PPh₃)(κ²(N,N-NC₉H₆NH₂-8) (6a, M = Ru; 6b, M = Os). In the case of ruthenium only, the intermediate ethanolysis product Ru(SiMeCl[OEt])Cl(CO)(PPh₃)(κ²(N,N-NC₉H₆NH₂-8) (6c) was also isolated. The crystal structure of 6c was determined. Reaction between 1b and excess 2-aminopyridine results in condensation between the Si-Cl bonds and the N-H bonds with formation of a novel tridentate “NSiN” ligand in the complex Os(κ³(Si,N,N)-SiMe[NH(2-C₅H₄N)]₂)Cl(CO)(PPh₃) (7b). Crystal structure determination of 7b shows that the “NSiN” ligand coordinates to osmium with a “facial” arrangement and with chloride trans to the silyl ligand.     

Synthesis and crystal structure of three new copper(II) complexes with a tridentate amine and its Schiff bases

Three new mononuclear complexes of copper(II), viz. [Cu(L)(N₃)Cl] (1), [Cu(L′)(H₂O)]ClO₄ (2) and [Cu(L″)] (3) where L = N-(3-aminopropyl)-N-methylpropane-1,3-diamine, L′ = 2-(N-{3-[(3-aminopropyl)(methyl)amino]propyl}ethanimidoyl)phenolate ion and L″ = 2,2′-{(methylimino)bis[propane-3,1-diylnitrilo(1E)eth-1-yl-1-ylidene]}diphenolate ion, have been prepared. The synthesis of complex 1 has been achieved by reacting copper chloride with the triamine (L) and sodium azide in a 1:1:1 M ratio. The other two compounds have been synthesized by the reaction of copper perchlorate with the same triamine, L, plus 2-hydroxyacetophenone in a molar ratio of 1:1:1 (for 2) and 1:1:2 (for 3), so that the respective tetradentate and pentadentate Schiff bases HL′ and H₂L″ are formed in situ to bind the copper(II) ions. The complexes have been characterized by microanalytical, spectroscopic and single crystal X-ray diffraction studies. Structural studies reveal that the mononuclear units of all the three complexes adopt a distorted square pyramidal geometry and are held together by either intermolecular H-bonding (in 1 and 2) or C-H?π interactions (in 3) to form supramolecular networks in the solid state.     

Syntheses,crystal structures,and properties of Ni(II) and Co(III) complexes derived from tripod polypyridine ligands containing N7 or N6 donor set atoms

New complexes [Ni^II(pbpaen)](ClO₄)₂ (1) and [Co^III(pbpaen)](ClO₄)₃ (2) (pbpaen = N′-(pyridin-2-ylmethyl)-N,N-bis {2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine) have been synthesized and characterized by IR and UV–Vis spectroscopies. An X-ray structure of the nickel(II) complex shows that [Ni(pbpaen)](ClO₄)₂ (1) crystallizes in the monoclinic space group P2_1/c. The cation [Ni(pbpaen)]²⁺ is pseudo-octahedral with one of the three pyridyl nitrogen atom uncoordinated. The crystal lattice of this complex is stabilized by intra and intermolecular hydrogen bonding systems, giving one-dimensional sheets like arrays. All attempts to obtain nickel or cobalt complexes with protonated forms of the ligand resulted in isolation of only [Co^III(bpaen)](ClO₄)₃ (3) compound in which the tripod pbpaen ligand has lost one of the three pyridylmethyl groups, procuring then bpaen ligand {bpaen = N,N-bis{2-[(pyridin-2-ylmethyl)amino]ethyl}ethane-1,2-diamine}. The X-ray crystal structure reveals that the compound 3 crystallizes in the orthorhombic space group Pna2 with the Co³⁺ ion having a distorted-octahedral environment. These two ligands with strong-field N donor stabilise the +3 oxidation state of the Co center.     

Synthesis, characterization, and norbornene polymerization of η-benzylnickel(II) complexes of N-heterocyclic carbenes

Neutral η¹-benzylnickel carbene complexes, [Ni(η¹-CH₂C₆H₅)(IiPr)(PMe₃)(Cl)] (3) (IiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) and [Ni(η¹-CH₂C₆H₅)(SIiPr)(PMe₃)(Cl)] (4) (SIiPr = 1,3-bis-(2,6-diisopropylphenyl)imidazolin-2-ylidene), were prepared by the reaction between [Ni(η³-CH₂C₆H₅)(PMe₃)(Cl)] and an equivalent amount of the corresponding free N-heterocyclic carbene. The preparation of η³-benzylnickel carbene complexes, [Ni(η³-CH₂C₆H₅)(IiPr)(Cl)] (5) and [Ni(η³-CH₂C₆H₅)(SIiPr)(Cl)] (6) were carried out by the abstraction of PMe₃ from 3 and 4 by the treatment of B(C₆F₅)₃. The treatment of AgX on 5 and 6 produced the anion-exchanged complexes, [Ni(η³-CH₂C₆H₅)(NHC)(X)] (7, NHC = IiPr, X = O₂CCF₃; 8, NHC = IiPr, X = O₃SCF₃; 9, NHC = SIiPr, X = O₂CCF₃; 10, NHC = SIiPr, X = O₃SCF₃). The solid state structures of 3 and 10 were determined by X-ray crystallography. The η³-benzyl complexes of IiPr (5, 7, and 8) alone, in the absence of any activators such as borate and MAO, showed good catalytic activity towards the vinyl-type norbornene polymerization. The catalyst was thermally robust and the activity increases as the temperature rises to 130 °C.     

Synthesis,characterization and antimicrobial activity of Ni(II) and Zn(II) complexes with N′,N′-bis[(1E)-1-(2-pyridyl)ethylidene]propanedihydrazide. Crystal structures of two highly solvated bimetallic complexes of Ni(II)

The bimetallic [Ni₂(H₂L2)₂](ClO₄)₄ (1), [Ni₂(HL2)(H₂L2)](ClO₄)₃ (2) and [Zn₂(H₂L2)₂](BF₄)₄ (3) complexes (H₂L2 = N′,N′²-bis[(1E)-1-(2-pyridyl)ethylidene]propanedihydrazide) were synthesized and characterized. The structure of complexes (1) and (2) was established by X-ray analysis. NMR spectroscopy was used for the characterization of complex (3). The complexes (1) and (2) were obtained from the same synthetic reaction and two crystal types of these complexes have been isolated during the fractional crystallization process.     

Syntheses,characterization and X-ray crystal structures of Ni(II) complexes of tridentate monocondensed and tetradentate dicondensed Schiff bases

Two octahedral complexes [Ni(HL¹)₂](ClO₄)₂ (1) and [Ni(HL²)₂](ClO₄)₂ (2) and a square planar complex [Ni(HL³)]ClO₄ (3) have been prepared, where [HL¹ = 3-(2-amino-ethylimino)-butan-2-one oxime, HL² = 3-(2-amino-propylimino)butan-2-one oxime] and H₂L³ = 3-[2-(3-hydroxy-1-methyl-but-2-enylideneamino)-1-methyl-ethylimino]-butan-2-one oxime. All the complexes have been characterized by elemental analyses, spectral studies and room temperature magnetic moment measurements. The molecular structures of all three compounds were elucidated on the basis of X-ray crystallography; complexes 1 and 2 are seen to be the mer isomers.     

An antiferromagnetically coupled dimeric Ni(II) complex anion and its counter cationic monomeric Ni(II) complex, and some other mononuclear transition metal compounds using some neutral ligands

Synthesis and single crystal X-ray diffraction studies of four transition metal complexes [Mn(L₁)](ClO₄)₂ (1), [Cu(L₁)](ClO₄)₂ (2), [Ni₂(L₂)(NCS)₆][Ni(L₁)] (3) and [Mn(bzpy)(NCS)₂] (4) with neutral ligands [L₁ = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-yl phenylidene)amino]ethyl}amino)ethyl]ethane-1,2diamine, L₂ = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-ylphenylidene)amino]ethyl}piperazine-1yl)ethyl]amine, bzpy = 2-benzoylpyridine] are reported. The trinuclear nickel(II) complex 3 is made of a dinuclear anion and a mononuclear cation. Variable-temperature magnetic susceptibility and variable-field magnetisation studies performed on 3 suggest weak antiferromagnetic coupling (J = −0.7 cm⁻¹) between the two metals of the dinuclear entity, but no magnetic interaction between the anionic and cationic counterparts.     

R-phenyldicarboxyl (R = H, NO2 and COOH) modular effect on Ni(II) coordination polymers incorporated with a versatile connector 1H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole

Based on the versatile ligand 1H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole (3,4′-Hbpt) (1), a series of coordination compounds [Ni(3,4′-Hbpt)(ip)] (2), [Ni(3,4′-Hbpt)₂(tp)(H₂O)₂] (3), [Ni₂(3,4′-Hbpt)(5-NO₂-ip)₂(H₂O)₄] (4) and [Ni(3,4′-Hbpt)(pm)_0.5(H₂O)₃]·2H₂O (5) have been hydrothermally constructed through R-phenyldicarboxyl (R = H, NO₂ and COOH) intervention effect (ip = isophthalic anion, tp = terephthalic anion, 5-NO₂-ip = 5-NO₂-isophthalic anion, pm = pyromellitic anion). Structural analysis reveals that 3,4′-Hbpt adopts μ-N_py, N_py coordination modes in two typical conformations in these target coordination compounds. In cooperation with the auxiliary ligands benzenedicarboxylate connectors, a variety of Ni(II) coordination networks such as 2-D layer with (4, 4) topology (2) 1-D chain (3), honeycomb (4) and 2-D helical chains (5) have been assembled. Theoretical calculation based on density functional theory (DFT) for ligand (1) is also employed to explicate the stability of the different conformations. Moreover, thermal stability of these crystalline materials is explored by TG-DTG.     

Syntheses, structures and ligand conformations of Cu(II), Co(II) and Ag(I) complexes containing the phosphinic amide ligands

The syntheses, structures and ligand conformations of the complexes trans-Cu(L1)₂(ClO₄)₂, (L1 = N-(2-pyrimidinyl)-P,P-diphenyl-phosphinic amide), 1, [trans-Co(L1)₂(CH₃OH)₂](ClO₄)₂·O(C₂H₅)₂, 2, [trans-Co(L2)₂(H₂O)₂](ClO₄)₂·2CH₃OH, (L2 = N-(2-pyridinyl)-P,P-diphenyl-phosphinic amide), 3, [cis-Co(L2)₂(NO₃)](NO₃), 4, and [Ag(L3)(NO₃)(CH₃CN)]_∞, (L3 = N-(6-methyl-2-pyridinyl)-P,P-diphenyl-phosphinic amide), 5, are reported. The L1 and L2 ligands in the monomeric complexes 1-4 chelate the metal centers through the pyrimidyl/pyridyl nitrogen atoms and the phosphinic amide oxygen atoms, whereas the L3 ligands in complex 5 bridge the metal centers, forming a 1-D zigzag chain. The chelating L2 ligands in complexes 3 and 4 adopt cis conformations and the bridging L3 ligand in complex 5 adopts a trans conformation, respectively.     

Copper(II) complexes with neutral Schiff bases: Syntheses, crystal structures and DNA interactions

The synthesis and X-ray structural characterisation of a new Cu(II) complex, [Cu(L¹)Cl](ClO₄)·CH₃OH (1) [L¹ = N,N′-bis((pyridine-2-yl)phenylidene)-1,3-diaminopropan-2-ol], has been described in this work. The structural study reveals that the Cu(II) centre in 1 has a square pyramidal geometry with a trigonality index τ = 0.43, being coordinated by the organic ligand and a chloro group. The interaction of complex 1 and another complex previously reported by our group, [Cu(L²)](ClO₄)₂ (2) [L² = N-(1-pyridin-2-yl-phenylidene)-N′-[2-({2-[(1-pyridin-2-ylphenylidene)amino]ethyl}amino)ethyl]ethane-1,2diamine], with calf thymus DNA (CT-DNA) has been investigated using absorption and emission spectral studies. The binding constant (K_b) and the linear Stern-Volmer quenching constant (K_sv) have been determined.     

Synthesis of arene ruthenium triazolato complexes by cycloaddition of the corresponding arene ruthenium azido complexes with activated alkynes or with fumaronitrile

The neutral arene ruthenium azido complexes [(η⁶-p-cymene)Ru(LL)(N₃)], [LL = acetylacetonato (acac) (4), benzoylacetonato (bzac) (5) diphenylbenzoyl methane (dbzm) (6)] undergo [3+2] cycloaddition reaction with a series of activated alkynes and fumaronitrile to produce the arene ruthenium triazolato complexes: [(η⁶-p-cymene)Ru(LL){N₃C₂(CO₂R)₂}] [LL = (acac), R = Me (7); LL = (bzac), R = Me (8); LL = (dbzm), R = Me (9); LL = (acac), R = Et (10); LL = (bzac), R = Et (11); LL = (dbzm), R = Et (12) and [(η⁶-p-cymene)Ru(LL)(N₃C₂HCN)]; LL = acac (13), bzac (14); dbzm (15). However, cationic azido complexes, [(η⁶-p-cymene)Ru(dppe)(N₃)]⁺ and [(η⁶-p-cymene)Ru(dppm)(N₃)]⁺ do not undergo such cycloaddition reactions. The complexes were characterized on the basis of microanalyses, FT-IR and NMR spectroscopic data. Crystal structures of representative complexes were determined by single crystal X-ray diffraction.     

Hetero-metallic frameworks of [Pd(CN)4] and Cu(II) with triamines: A rare example of a tetracyanometallate bridged 2D coordination polymer

Four cyano bridged Cu(II)–Pd(II) heterometallic complexes, [Cu(dpt)Pd(CN)₄]_n (1), {[Cu₂(medpt)₂Pd(CN)₄](ClO₄)₂ · 3H₂O}_n (2), {[Cu₂(dien)₂Pd(CN)₄](ClO₄)₂ · 2CH₃OH}_n (3) and {[Cu₂(iPrdien)₂Pd(CN)₄](ClO₄)₂ · 2H₂O}_n (4) [dpt = 3,3′-iminobispropylamine; medpt = 3,3′-diamino-N-methyldipropylamine; dien = diethylenetriamine and iprdien = N′-isopropyldiethylenetriamine] have been synthesized and characterized by single crystal X-ray diffraction analysis, magnetic measurement and thermal study. Complexes 1, 2 and 3 are 1D coordination polymers, while 4 presents a 2D network. In 1, the cis-directed cyanide ligands of [Pd(CN)₄]²⁻ anions link two Cu(dpt) units to form a neutral coordination polymer, whereas in 2, 3 and 4, all the cyanide groups of [Pd(CN)₄]²⁻ take part in bonding with four adjacent Cu(II) ions, resulting in cationic coordination polymers counterbalanced by perchlorate anions. The structures are compared with those of analogous [Ni(CN)₄]²⁻ derivatives. The magnetic behavior shows antiferromagnetic interactions in all the complexes.     

Co(II), Ni(II) and Zn(II)-orotate complexes with N-methylimidazole: Synthesis, crystal structures and antimicrobial activities

Three Co(II), Ni(II) and Zn(II) complexes of orotate with the N-methylimidazole ligand were synthesized and characterized by means of elemental and thermal analysis, magnetic susceptibilities, IR, UV-Vis spectroscopic and antimicrobial activity studies. The crystal structures of [Co(HOr)(H₂O)₂(Nmeim)₂]₃·H₂O (1), [Ni(HOr)(H₂O)₂(Nmeim)₂] (2) and [Zn(HOr)(H₂O)(Nmeim)₂] (3) were determined by the single crystal X-ray diffraction technique (H₃Or = orotic acid and Nmeim = N-methylimidazole). In complexes 1 and 2, the Co(II) and Ni(II) ions have distorted octahedral geometries with two Nmeim, one orotate and two aqua ligands. Complex 3 has a distorted trigonal bipyramidal geometry with two N-methylimidazole, one orotate and one aqua ligands. In the complexes, the orotate is coordinated to the metal(II) ions through the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group as a bidentate ligand. The complexes form a three-dimensional framework by hydrogen bonding, C-H?π and π?π stacking interactions. The MIC values of the complexes against selected microorganisms were determined to be in range 300-2400 μg/mL.