Cyanide-bridged Complexes Research Articles

A serial of cyanide-bridged CrIII/I[sbnd]CuII complexes from 0D cluster to 2D network: Synthesis, crystal structure and magnetic property

One cyanide-bridged heterometallic achiral complex and two pairs of enantiomers {[Cu(Chxn)2Cr(bpb)(CN)2]ClO4}·CH3OH·H2O (1), {[Cu(S,S/R,R-Chxn)2Cr(CN)5(NO)]2[Cu(S,S/R,R-Chxn)2(H2O)2]}n·3nH2O (2, 3) {[Cu(S,S/R,R-Chxn)2]3[Cr(CN)5(NO)]2}n·5nH2O (4, 5). (bpb = bis(2-benzimidazolyl)pyridine dianion, Chxn = 1,2-diaminocyclohexane) have been assembled from two cyano containing Cr(I) or Cr(III) building blocks, K[Cr(bpb)(CN)2] and K3[Cr(CN)5(NO)], and racemic or chiral copper(II) compounds under the different reaction conditions. The complexes have been characterized by element analysis, IR spectra, the circular dichroism (CD) spectrum, powder and single crystal X-ray diffraction. X-ray structural analyses revealed that the divers structure types of complexes 1–5 ranging from discrete polynuclear entity (1), 1D coordination polymer (CP) anionic chain (2, 3) to neutral 2D CP network (4, 5), indicating clearly the important role of the building block and preparation method on tuning the structure of the target cyanide-bridged complexes. The magnetic properties for the reported complexes have been experimentally studied and theoretically simulated, disclosing the ferromagnetic coupling between the Cr(III) ion and Cu(II) ion and the rare antiferromagnetic interaction within Cr(ICu(II) unit through the cyanide bridge, respectively. Furthermore, the magnetic coupling nature has been analyzed based-on the magneto-structural correlation.

Influence of the electronic effect of an ancillary ligand on MMCT and LMCT in localized cyanide-bridged complexes containing non-innocent ligands.

Mixed-valence (MV) complexes containing non-innocent ligands are excellent models for the investigation of the electron-transfer process. A series of twelve bimetallic cyanide-bridged complexes [CpMen(dppe)RuCNFeLx][A] (A = PF6- or I-, CpMen = alkyl cyclopentadienyl, dppe = 1,2-bis (diphenylphosphino)ethane, and LX = pentane-2,4-dione-bis (S-alkylisothiosemi-carbazonato); n = 0, x = Methyl (Me), Ethyl (Et), n-Propyl (Pr) and n-Butyl (Bu), and A = PF6-, 1Me[PF6], 1Et[PF6], 1Pr[PF6], and 1Bu[PF6]; n = 1, x = Me, Et, Pr, and Bu, and A = PF6-, 2Me[PF6], 2Et[PF6], 2Pr[PF6], and 2Bu[PF6]; n = 5, x = Me, Et, Pr, and Bu, and A = I-, 3Me[I], 3Et[I], 3Pr[I], and 3Bu[I]) have been synthesized and well characterized. The investigations demonstrate that all the cations of the complexes could be described with the basic electronic configuration , in which the fragment could be regarded as being delocalized. The ligand to metal charge transfer (LMCT) transition in the fragment and the low-spin RuII to the intermediate-spin FeIII charge transfer (MMCT) transition have been investigated. The UV-vis-NIR spectral analysis results suggest that the energy of the LMCT transition is lower than that of the MMCT transition due to electron delocalization between the non-innocent ligand and the FeIII ion, which is strongly supported by TDDFT calculations. Furthermore, the RuII → FeIII MMCT energy decreases and the LMCT energy increases with the increasing electron donating ability of the ancillary ligands from Cp, CpMe to CpMe5, but slightly changes with the variation of the ligand Lx from Me, Et, Pr to Bu. Compared to the MMCT energy change, however, the energy of the LMCT from to FeIII in the delocalized moiety is less influenced by the electronic effect of the ancillary ligand or the CpMen(dppe)RuIICN (n = 0, 1 and 5) fragment.

Cyanide Bridged Platinum-Iron Complexes as Cisplatin Prodrug Systems: Design and Computational Study.

The potential role of cyanide-bridged platinum-iron complexes as an anti-cancer Pt(IV) prodrug is studied. We present design principles of a dual-function prodrug that can upon reduction dissociate and release concurrently six cisplatin units and a ferricyanide anion per prodrug unit. The prodrug molecule is a unique complex of hepta metal centers consisting of a ferricyanide core with six Pt(IV) centers each bonded to the Fe(III) core through a cyano ligand. The functionality of the prodrug is addressed through density functional theory (DFT) calculations.

Bimetallic and trimetallic chains of Fe-CN-Ln complexes: Synthesis, structural characterization, and magnetic properties

Two new one-dimensional cyanide-bridged complexes, [Gd (DMF)4(H2O)2{Fe(CN)6}]·H2O (1) and [{CuL}Gd(H2O)3{Fe(CN)6}]·3H2O (2) (H2L = N,N'-(2-Hydroxy-propane-1,3-diyl)bis(3-methoxysalicylaldiimine) were obtained in the attempt of constructing heterotrimetallic 3d-3d′-4f systems with these reaction precursors. Interestingly, the two complexes show rather comparable structures with a chain-like skeleton, although one features a typical bimetallic structure while the other behaves as a trimetallic system. To the best of our knowledge, the complexes are new in the Fe-CN-Ln family, which is especially suitable for magnetic study of the role of the third metal ions in the system. X-ray diffraction results clearly indicated the formation of the interesting chain structures of these complexes, which were further confirmed by magnetic investigation.

Manipulating Slow Magnetic Relaxation by Light in a Charge Transfer {Fe2 Co} Complex.

Some cyanide-bridged complexes are known for exhibiting slow magnetic relaxation behavior in a light-induced metastable state. Herein, an unexpected reverse effect is observed for the first time in the S= {FeII LS -CoIII LS -FeIII LS } (HS=high spin, LS=low spin) ground state of a novel V-shaped trinuclear cyanide-bridged {Fe2 Co} complex. In this complex, light-switchable iron-cobalt charge transfer with repeatable off/on switching of slow magnetic relaxation is discovered upon alternating laser irradiation at 785 and 560 nm. An important characteristic of the present compound is that the S= ground state exhibits slow magnetic relaxation before irradiation, whereas this is accelerated after irradiation. This is different from the typical behavior, where the light-induced metastable state exhibits slow magnetic relaxation.

Heterobimetallic complexes from 0D clusters to 3D networks based on various polycyanometallates and [Cu(dmpn)2]2+ (dmpn = 2,2-dimethyl-1,3-diaminopropane): synthesis, crystal structures and magnetic properties

Six new cyanide-bridged complexes (0–3D) have been assembled by employing one copper compound and six cyano precursors. Investigation of the magnetic properties revealed the ferro- or antiferromagnetic coupling between FeIII/CrI ion and CuII ion.

Three Cyanide-Bridged Fe <sup>II</sup>-M <sup>II</sup> (M = Fe, Co and Mn) Complexes: Synthesis, Crystal Structures and Magnetic Properties

Three dinuclear cyanide-bridged complexes Fe II (PY 5 OMe 2 )CNM II (PY 5 OMe 2 )[OTf] 3 (M = Fe 1 , Co 2 , Mn 3 ; PY 5 OMe 2 = 2,6-bis-((2-pyridyl)methoxymethane)pyridine OTf = CF 3 SO 3- ) have been synthesized and characterized. Single-crystal diffraction analyses show these three dinuclear compounds are very similar in structure. And the M-N (M = Fe, Co and Mn) bond lengths for complexes 1 - 3 indicate that 2 and 3 are typical of a high spin (HS) complexes and 1 is evident a low spin (LS) Fe (II) complex at room temperature, confirmed by the temperature dependence of magnetic susceptibilities of complexes 1-3 . The different magnetic behaviors of complexes 1 - 3 reveal that in the three complexes all the cyanide-carbon coordinated Fe (II) are low-spin, and Co (II) for 2 and Mn (II) for 3 are both in a high-spin state through 2-400 K but the cyanide-nitrogen coordinated Fe (II) for complex 1 begins to occur a spin crossover (SCO) transition from 300 K.

Experimental and theoretical studies on the molecular structures and vibrational spectra of cyanide complexes with 1,2-dimethylimidazole: [M(dmi)2Ni(μ-CN)4]n (M = Cu, Zn or Cd)

A new Cu(II)/Ni(II) heterometallic cyanide-bridged complex of 1,2-dimethylimidazole (dmi), [Cu(dmi)2Ni(μ-CN)4]n was synthesized and its structure was characterized by FT-IR, Raman, single-crystal X-ray diffraction (SC-XRD) and thermal/elemental analysis techniques. In our previous study, we reported cyanide-bridged zinc(II) and cadmium(II) complexes with 1,2-dimethylimidazole (dmi), [M(dmi)2Ni(μ-CN)4]n (M(II) = Zn or Cd), and determined their structures, experimentally. The crystallographic analyses reveal that the complexes have polymeric 2D networks. In the complexes, four cyanide groups of [Ni(CN)4]2- coordinated to the adjacent M(II) ions and distorted octahedral geometries of the complexes are completed by two nitrogen atoms of trans dmi ligands. The structures of the complexes similar and linked via intermolecular hydrogen bonding, C–H⋅⋅⋅Ni interactions to give rise to 3D networks. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the complexes were examined by means of the density functional theory (DFT) method, the Becke-3-Lee-Yang-Parr (B3LYP) functional and the LANL2DZ basis set. Additionally, the optimized geometries were investigated with time depended density functional theory (TD-DFT) method and the LANL2DZ basis set on the singlet and triplet states in order to obtain electronic transitions. These results were provided the electronic behaviors during the excitations on the complexes and dmi.

Cyanide-bridged polynuclear heterobimetallic complexes: synthesis, crystal structures, and magnetic properties

The reactions of [MnIII(3-EtOSalen)(H2O)2]ClO4 (Salen=N,N-ethylenebis(salicylideneaminato)dianion) with K3[M(CN)8] (M=Mo, W) have been investigated, from which cyanide-bridged hexanuclear Mo–Mn and binuclear W–Mn complexes formulated as {[Mn(3-EtOSalen)(H2O)]4[Mn(3-EtOSalen)(CH3OH)][MoCN8]}(CN)2·CH3CN·H2O (1) and {[Mn(3-EtOSalen)(H2O)2][Mn(3-EtOSalen)(H2O)(EtOH][MnIII(3-EtOSalen)(H2O) W(CN)8]}·0.5CH3OH (2), respectively, were obtained and characterized by elemental analysis, IR spectroscopy and X-ray crystal structure determination. X-ray diffraction analysis for complex 1 shows that it has a cyanide-bridged cationic hexanuclear Mn5Mo structure in which two free and disordered CN− ions from the cyanide precursor are present as balance anions, while the [Mo(CN)8]3− ion acting as a pentadentate ligand connects five Schiff base manganese(III) units. In complex 2, the [W(CN)8]3− ion is coordinated with a single Schiff base manganese unit by one of its cyanide groups, so forming a cyanide-bridged anionic binuclear structure whose dinegative charge is balanced by two free Schiff base manganese cations. Both of these cyanide-bridged complexes can be considered as self-complementary, such that the coordinated aqua ligand from one complex and the O4 compartment from the Schiff base ligand of the neighboring complex form a supramolecular two-dimensional network and a one-dimensional ladder-like double-chain structure, respectively. Investigation of the magnetic properties of these complexes reveals antiferromagnetic interactions within the cyanide-bridged Mn–Mo/W units. The magnetic susceptibilities of both complexes have been modeled.

Polyazamacrocyclic copper based cyanide-bridged bimetallic sandwich-like complexes: Synthesis, crystal structure and magnetic properties

By employing three dicyanometallates as building blocks, K[Fe(bpb)(CN)2], K[Cr(bpb)(CN)2] (bpb2– = 1,2-bis(pyridine-2-carboxamido)benzenate), K[Fe(bpmb)(CN)2] (bpmb2– = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate) and one 14-membered polyazamacrocycle Cu(II) compound as assembling segment, three cyanide-bridged complexes {[Cu(6,13-Dihydroxylcyclam)][Fe(bpb)(CN)2]2}·2CH3OH·H2O (1), {[Cu(6,13-Dihydroxylcyclam][Cr(bpb)(CN)2]2}·2CH3OH (2) and {[Cu(6,13-Dihydroxylcyclam)][Fe(bpmb)(CN)2]2}·2H2O (3) (6,13-Dihydroxylcyclam = 6,13-Dihydroxyl-1,4,8,11-tetraazacyclotetradecane) have been successfully prepared and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis shows that all the three complexes containing the M2Cu (M = Fe, Cr) core present the neutral trinuclear sandwich-like structures, in which the central Cu(II) ion was coordinated face-to-face to the two Fe or Cr ions of the cyanide precursors functioning as a monodentate ligand through one of its two cyanide groups. Investigation over their magnetic properties reveals the antiferromagneitic and ferromagnetic coupling between the cyanide-bridged Fe(III)—Cu(II) and Cr(III)—Cu(II) ions, respectively.

Influence of ligand substitution at the donor and acceptor center on MMCT in a cyanide-bridged mixed-valence system.

We detail the rational design of bimetallic cyanide-bridged complexes [TpmRu(LD)(μ-CN)Ru(LP)Cp*][PF6]2 (Tpm = Tris(1-pyrazolyl)methane, LD = 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (dbpy), LP = bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)ethane (dppe), Cp* = 1,2,3,4,5-pentamethylcyclopentadiene). The metal-to-metal charge transfer (MMCT) properties of these one-electron oxidized complexes were investigated, suggesting that the substitution of the ancillary ligand provides a strong impetus to systematically tune the MMCT properties. The investigation results indicate that all the mixed-valence complexes belong to Class II mixed-valence complexes, according to the Robin-Day classification.

Synthesis, crystal structure and MMCT of a heterobimetallic cyanide-bridged complex trans-BrRuII(dppe)2(μ-CN)(FeIIIBr3)

The syntheses, crystal structures, IR and electronic absorption spectroscopy of cyanide-bridged complex trans-BrRuII(dppe)2(μ-CN)(FeIIIBr3) (2) and its parent trans-ClRuII(dppe)2(CN) (1) were reported. The crystals crystallized in the monoclinic space group C2/c for 1, and monoclinic space group P21/c for 2. The crystal structural data, MMCT (metal-to-metal charge transfer) in electronic absorption spectra and EPR spectra indicate the existence of some electron delocalization along FeIIINCRuII in complex 2. The magnetic properties of complex 2 were measured and analyzed.

Hydrogen-Bond Directed Cyanide-Bridged Supramolecular 2D and 1D Bimetallic Coordination Polymers: Synthesis, Crystal Structure, and Magnetic Properties

By using K2[Ni(CN)4] as a building block and two Mn(III) compounds containing bicompartimental Schiff-base ligands as assembling segments, two new cyanide-bridged Ni–Mn complexes of the formula {[Mn(L1)(H2O)]4[Ni(CN)4]}[ClO4]2·2CH3CN (1) and {[Mn(L2)(H2O)]2[Ni(CN)4]}·CH3CN H2O (2) (L1 = N,N’-1,2-propylene-bis(3-methoxysalicylideneiminate; L2 = N,N’-1,2-propylene-bis(3-ethoxysalicylideneiminate) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray analysis. Single Xray diffraction analysis revealed the cationic pentanuclear and neutral trinuclear structures for complexes 1 and 2, respectively, and indicated that the structure of the Schiff-base ligand had obvious influence on the structural types of the target cyanide-bridged complexes. Both cyanide-bridged complexes are self-complementary via coordinated aqua ligand from one complex and the free O4 compartment from the neighboring complex, therefore giving supramolecular two-dimensional network and one-dimensional zig-zag chain structure. Study of magnetic properties revealed weak antiferromagnetic coupling within the Mn2 dimer formed by the intermolecular hydrogen bond.

Polynuclear and one-dimensional cyanide-bridged heterobimetallic complexes: synthesis, crystal structures and magnetic properties

Three new heterobimetallic cyanide-bridged complexes, $$\{[\hbox {Ni}(\hbox {L}^{1})][\hbox {Ag(CN)}_{2}]\} [\hbox {Ag(CN)}_{2}]\cdot \hbox {2H}_{2}\hbox {O}$$ (2), $$\{[\hbox {Mn}(\hbox {L}^{2})][\hbox {Ag(CN)}_{2}]\}\cdot 1.5\hbox {H}_{2}\hbox {O}$$ (3) and $$\{[\hbox {Mn}(\hbox {L}^{3})(\hbox {H}_{2}\hbox {O})]_{2}[\hbox {Ag(CN)}_{2}]\} \hbox {ClO}_{4}\cdot \hbox {2H}_{2}\hbox {O}$$ (4) ( $$\hbox {L}^{1 }$$ = 2,7,12-trimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene; $$\hbox {L}^{2}$$ = N,N’-1,3-propylene-bis(5-chlorosalicylideneiminate); $$\hbox {L}^{3}$$ = N,N’-1,2-propylene-bis(5-bromosalicylideneiminate)), have been assembled using for the first time a new polyaza macrocycle nickel(II) compound $$[\hbox {Ni}(\hbox {L}^{1})](\hbox {ClO}_{4})_{2}$$ (1), or Schiff-base manganese(III) compounds and $$\hbox {K}[\hbox {Ag(CN)}_{2}$$ ]. Single crystal X-ray diffraction analysis reveals that complexes 2 and 3 can be characterized as one-dimensional cationic and neutral single chain structure, respectively. Complex 3 forms a three-dimensional network via weak inter-chain Ag...Ag interactions. Complex 4 belongs to a cyanide-bridged bimetallic sandwich-like cationic trinuclear structure containing $$\hbox {Mn}_{2}\hbox {Ag}$$ core with free $$\hbox {ClO}_{4}^{-}$$ as a counter anion, indicating that the Schiff-base ligand has an obvious influence on the structure of the cyanide-bridged complexes formed. Investigation of the magnetic susceptibilities of the cyanide-bridged Ag-Ni(II)/Mn(III) complexes showed the weak anti-ferromagnetic interaction between neighboring paramagnetic Ni(II) or Mn(III) ions bridged by the long NC-Ag-CN unit. From the best-fit of the magnetic susceptibility data of complexes 2 and 4 the magnetic coupling constant was determined to be $$J = -0.51$$ and $$-0.78 \,\hbox {cm}^{-1}$$ , respectively. SYNOPSIS Three new heterobimetallic cyanide-bridged complexes with 1D or polynuclear structures were assembled from polyaza macrocycle nickel(II) or manganese(III) Schiff-base with $$\hbox {K}[\hbox {Ag(CN)}_{2}$$ ] as building block. Investigation over the magnetic susceptibilities of the cyanide-bridged Ag-Ni(II)/Mn(III) complexes showed weak antiferromagnetic interaction between neighboring Ni(II) or Mn(III) ions bridged by the NC-Ag-CN unit.

Synthesis and photophysical properties of bis(phenylpyridine) iridium(III) dicyanide complexes

Our research group is focusing on luminescence of coordination compounds which based on cyanide bridging interactions. Recently, four cyanometallate complexes based on Ir(III) complex [Ir(ppy)2(CN)2]-, which is one of an extensive family of Ir(III) complexes based on cyclometallating phenylpyridine ligands that have achieved prominence for their desirable photophysical properties, were successfully synthesised. The present study showed that, the introduction of fluorine atoms to the phenyl rings could enhance the triplet excited state energy and thus caused a blue-shift phosphorescence peak (λem = 453 nm) as shown by (PPN)[Ir(2,4-F2ppy)2(CN)2] (1) compared to that of complex without fluorine atom (PPN)[Ir(ppy)2(CN)2] (4) (λem=474 nm). However, (PPN)[Ir(3,5-F2ppy)2(CN)2] (2) shows a negligible hypsochromic shift (λem = 473 nm) in the emission. Conversely, (PPN)[Ir(4-CF3ppy)2(CN)2] (3) shows a red-shift (λem = 479 nm) compared to complex (4). These complexes, like [Ru(bipy)(CN)4]2−, have a strong emissive and high energy excited state and thus, are potentially good energy donors; and are anionic with cyanide groups, and so can form cyanide-bridged complexes with other metal and lanthanide cations.

A novel tetrazolate- and cyanide-bridged three-dimensional heterometallic coordination polymer: crystal structure, thermal stability and magnetic properties.

By using environmentally friendly K3[Co(CN)6] as a cyanide source, the solvothermal reaction of CuCl2 and tetrazole (Htta) led to a novel tetrazolate- and cyanide-bridged three-dimensional heterometallic CuII-CoIII complex, namely poly[[hexa-μ2-cyanido-κ12C:N-pentakis(μ3-tetrazolato-κ3N1:N2:N4)cobalt(III)tetracopper(II)] monohydrate], {[CoIIICuII4(CHN4)5(CN)6]·H2O}n, (I). The crystal structure analysis reveals that it is the first example of a (6,8,8)-connected three-dimensional framework with a unique topology, constructed from anionic [Co(CN)6]3- and cationic [(Cu1)2(tta)2]2+ and [(Cu2Cu3)(tta)3]+ units through μ2-cyanide and μ3-tetrazolate linkers. The compound was further characterized by thermal analysis, vibrational spectroscopy (FT-IR), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS) and magnetic measurements. The magnetic investigation indicates that the complex exhibits antiferromagnetic coupling between adjacent CuII cations.

Three 1D cyanide-bridged M(Ni, Pd, Pt)-Mn(II) coordination polymer: synthesis, crystal structure and magnetic properties

Three tetracyanide-containing building blocks K2[M(CN)4] (M = Ni, Pd, Pt) and one semi-closed macrocycle seven-coordinated manganese(II) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in three cyanide-bridged MII-MnII complexes: [Mn(L)][Ni(CN)4] · 2H2O (1) [Mn(L)][Pd(CN)4] (2) and [Mn(L)][Pt(CN)4] (3) (L = 2,6-bis[1-(2-(N-methylamino)ethylimino)ethyl]pyridine). Single-crystal X-ray diffraction analysis shows their similar one-dimensional structure consisting of the alternating [Mn(L)]2+ species and [M(CN)4]2- building blocks, generating a cyanide-bridged neutral polymeric chain. In all three isostructural complexes the coordination geometry of manganese ion is a slightly distorted pentagonal-bipyramidal with the two cyanide nitrogen atoms at the trans positions and N5 coordinating mode at the equatorial plane from ligand L. Investigation over magnetic properties of these complexes reveals very weak antiferromagnetic interaction between neighboring Mn(II) ions bridged by the long NC-M-CN unit. A best-fit to the magnetic susceptibility of complexes 1-3 leads to the magnetic coupling constant of J = -0.081, -0.103 and -0.14 cm-1, respectively.

Redox effects of low-spin Ru(ii/iii) on slow magnetic relaxation of Ru-Mn(iii) 1D cyanide-bridged complexes.

A new one-dimensional cyanide-bridged complex [MnIII(salphen)RuII(DMAP)4(CN)2](PF6) (1) and its oxidized derivative [MnIII(salphen)RuIII(DMAP)4(CN)2](PF6)2 (2) have been synthesized and fully characterized. Magnetic measurements showed that 1 shows simple paramagnetism but 2 shows intrachain ferromagnetic interaction with slow magnetic relaxation.

Exploring the localized to delocalized transition in non-symmetric bimetallic ruthenium polypyridines.

In this work, we report the evolution of the properties of the inter-valence charge transfer (IVCT) transition in a family of cyanide-bridged ruthenium polypyridines of general formula [RuII(tpy)(bpy)(μ-CN)RuIII(bpy)2(L)]3/4+ (tpy = 2,2',6',2''-terpyridine; bpy = 2,2'-bipyridine; L = Cl-, NCS-, 4-dimethylaminopyridine or acetonitrile). In these complexes, the redox potential difference between both ruthenium centers (ΔE) is systematically modified. A decrease in ΔE causes a red shift of the energy and an intensity enhancement of the observed IVCT transitions. For L = acetonitrile, the IVCT band becomes narrower and asymmetrical, and shows very little dependence on the nature of the solvent, suggesting a delocalized configuration, although a non-symmetrical one. Also, additional electronic transitions of low energy are clearly resolved in this complex. The observed variation in the properties of the IVCT transitions can be understood on the basis of DFT calculations, that point to increasing mixing between the dπ orbitals of both Ru ions.

Syntheses and characterizations of the cyanide-bridged heteronuclear polymeric complexes with 2-ethylimidazole

Three new cyano-bridged heteronuclear polymeric complexes, [Cu( etim ) 3 Ni(CN) 4 ] n , {[Zn( etim ) 3 Ni(CN) 4 ]∙H 2 O} n and [Cd( etim ) 2 Ni(CN) 4 ] n ( etim = 2-ethylimidazole, hereafter abbreviated as Cu–Ni– etim , Zn–Ni– etim and Cd–Ni– etim ) have been prepared in powder form and characterized by FT-IR and Raman spectroscopies, thermal (TG, DTG and DTA) and elemental analyses. The spectral features of the complexes suggest that the Ni(II) ion is four coordinate with four cyanide-carbon atoms in a square planar geometry, whereas the Cu(II) and the Zn(II) ions of the Cu–Ni– etim and the Zn–Ni– etim complexes are completed by nitrogen atoms of two cyano groups of [Ni(CN) 4 ] 2- coordinated to the adjacent M(II) ions and three nitrogen atoms of the etim ligands. The Cd(II) ion of the Cd–Ni– etim complex is six-coordinate, completed with the two nitrogen atoms of the etim ligands and the four nitrogen atoms from bridging cyano groups. Polymeric structures of the Cu–Ni– etim and the Zn–Ni– etim complexes are 1D coordination polymer, while complex the Cd–Ni– etim presents a 2D network. The thermal decompositions in the temperature range 30–700 °C of the complexes were investigated in the static air atmosphere. KEY WORDS : Tetracyanonickelate(II) complex, 2-Ethylimidazole complex, Cyanide-bridged complex, Vibration spectra, Thermal analysis Bull. Chem. Soc. Ethiop. 2016 , 30(2), 263-272. DOI: http://dx.doi.org/10.4314/bcse.v30i2.10