共查询到20条相似文献,搜索用时 31 毫秒
1.
The ligand exchange reaction of the anionic binuclear rhenium complexes (R = H (1) or Me (2)) has been studied with the carboxylic acids; benzoic acid (3, 4, and 5), fumaric acid (6), and terephthalic acid (7). The exchange with benzoic acid can be controlled by stoichiometry to one, two, or three substitutions. The doubly (4) and triply (5) substituted complexes represent new structural motifs for the triply bridged Re2(CO)6 unit. The dicarboxylic acids fumaric and terephthalic bridge two dirhenium centers. Crystal structure determinations have been carried out for the new complexes synthesized. 相似文献
2.
Four new ternary copper(II) complexes of α-amino acid having polypyridyl bases of general formulation [Cu(l-ala)(B)(H2O)](X) (1-4), where l-ala is l-alanine, B is an N,N-donor heterocyclic base, viz. 2,2′-bipyridine (bpy, 1), 1,10-phenanthroline (phen, 2) and 5,6-phenanthroline dione (dione, 3), dipyrido[3,2:2′,3′-f]quinoxaline (dpq, 4), and X = / are synthesized, characterized by various spectroscopic and X-ray crystallographic methods. The complexes show a distorted square-pyramidal (4 + 1) CuN3O2 coordination geometry. The one-electron paramagnetic complexes (1-4) display a low energy d-d band near 600 nm in aqueous medium and show a quasi-reversible cyclic voltammetric response due to one-electron Cu(II)/Cu(I) reduction near −100 mV (versus SCE) in DMF-0.1 M TBAP. Binding interactions of the complexes with calf thymus DNA (CT-DNA) were investigated by UV-Vis absorption titration, ethidium bromide displacement assay, viscometric titration experiment and DNA melting studies. All the complexes barring the complexes 1 and 3 are avid binder to the CT-DNA in the DNA minor groove giving an order: 4 > 2 ? 1, 3. The complexes 2 and 4 show appreciable chemical nuclease activity in the presence of 3-mercaptopropionic acid (MPA) as a reducing agent. Hydroxyl radical was investigated to be the DNA cleavage active species. Control experiments in the presence of distamycin-A show primarily minor groove-binding propensity for the complexes 2 and 4 to the DNA. 相似文献
3.
Raquel Gracia 《Inorganica chimica acta》2010,363(14):3856-3864
A series of complexes containing the bulky carboxylate ligand 2,4,6-triisopropylbenzoate (TiPB) of type trans-[Ru2(TiPB)2(O2CCH3)2X] [X = Cl (1), PF6 (2)] and [Ru2(TiPB)4X] [X = Cl (3), PF6 (4)] have been synthesised. The corresponding complexes trans-[Ru2(TiPB)2(O2CCH3)2] (5) and [Ru2(TiPB)4] (6) were also isolated. Magnetic susceptibility measurements indicate that the diruthenium cores have the expected three (1-4) or two (5 and 6) unpaired electrons consistent with σ2π4δ2(δ∗π∗)3 and σ2π4δ2δ∗2π∗2 electronic configurations. Compounds 1-4 and 6 were structurally characterised by X-ray crystallography, and show the expected paddlewheel arrangement of carboxylate ligands around the diruthenium core. The diruthenium cores of complexes 3, 4 and 6 are all distorted to minimise steric interactions between the bulky carboxylate ligands. The Ru-Ru bond length in the complex 6 [2.2425(6) Å] is the shortest observed for a diruthenium tetracarboxylate and, surprisingly, is 0.014 Å shorter than in the analogous complex 4, despite an increase in the formal Ru-Ru bond order from 2.0 (6) to 2.5 (4). This is rationalised in terms of the extent of internal rotation, or distortion, about the diruthenium core. This was supported by density functional theory calculations on the model complexes [Ru2(O2CH)4] and [Ru2(O2CH)4]+, that demonstrate the relationship between Ru-Ru bond length and internal rotation. Electrochemical and electronic absorption data were recorded for all complexes in solution. Comparison of the data for the ‘bis-bis’ (1, 2 and 5) and tetra-substituted (3, 4 and 6) complexes indicates that the shortening of the Ru-Ru bond length results in a small increase in energy of the near-degenerate δ∗ and π∗ orbitals. 相似文献
4.
The ligands bis-(imidazolium) hexafluorophosphate (Himy = -C3N2H3-, imidazolium; R = 1-naphthylmethylene, 1a; 9-anthracenylmethylene, 1b) with an oxoether chain were easily prepared by the reaction of substituted imidazole with the diglycol diiodide, followed by exchange of anions with . 1a and 1b reacted with Ag2O in DMSO or CH3CN to yield [2 + 2] dinuclear Ag(I) NHCs macrocyclic complexes 2a and 2b, which showed much different conformation in solid corresponding to the R- substituent. Carbene transmetalation reactions of 2a-b with Au(SMe2)Cl give dinuclear Au(I) analogs 3a and 3b. The new NHCs complexes were characterized by elemental analyses, 1H NMR, 13C NMR and the structures of 2a-b and 3a were confirmed by X-ray diffraction determination. 相似文献
5.
The reaction of 1,3-bis(4,5-dihydro-1H-imidazol-2-yl)benzene (bib) ligand with silver(I) nitrate in a 1:1 molar ratio generated a [2 + 2] metallocyclic complex [Ag2(bib)2](NO3)2 · 2H2O, in which bib ligand displayed in cis configuration. When the additional competing ligands/counterions, such as oxlate salt, 1,2-diaminoethene (en), 1,3-diaminopropane (pn), and were introduced, respectively, to the above-mentioned reaction solution, ring-open polymerization of sliver(I) complexes {[Ag(bib)]NO3 · H2O}n (1), {[Ag(bib)2]X}n ( (2), (3)), {[Ag2(bib)2(NO2)](NO2) · 19/8H2O}n (4) and {[Ag2(bib)2](V4O12)0.5 · 3H2O · 2MeCN}n (5) were generated. In compounds 1, 4 and 5, bib ligand adopts trans configuration and twists around the Ag-Ag axis, giving rise to single-stranded helical structure with short adjacent Ag?Ag distances of 3.56, 3.56, 3.50 and 3.63 Å, respectively. Compounds 2 and 3 are 1D coordination polymers fusing the [2 + 2] metallocycle [Ag2(bib)2]2+, in which bib ligand exhibits in cis configuration and the metallocycles have longer Ag?Ag distances of 8.52 Å in 2 and 8.61 Å in 3 along with the strong intracyclicπ-π interactions between phenyl groups. Cis and trans configurations of bib coexist in solution and crystallize in complexes 1 and 2 in the solid state in the presence of en or pn. The solution of 1 and 2 can be converted into 3 via the addition of the bulky counter anion or into 4 through introduction of the competing ligand/conuterion . 相似文献
6.
Three new iron(III) citrate complexes [Fe2(cit)2(H2O)2](H2bpa) (1), [Fe2(cit)2(H2O)2](H2bpe) (2) and [Fe4(cit)4(H2O)4](H2bpp)2(H2O) (3) (cit = C(O−)(COO−)(CH2COO−)2, bpa = 1,3-bis(4-pyridyl)ethane, bpe = 1,3-bis(4-pyridyl)ethene, bpp = 1,3-bis(4-pyridyl)propane) were synthesized and characterized by elemental analysis, spectroscopic techniques and magnetic properties. Single X-ray diffraction analyses in the 1-3 complexes reveal that the iron ion is six-coordinated and is bound by two deprotonated citrates and a pair of aqua ligands in a distorted octahedral fashion. The anionic complex contains a centro-symmetrical planar of four-membered Fe2O2 ring. There are significant contributions to the stabilities of the assembled lattices in 1-3 arising from the protonated pyridine analogue counterions neutralizing the anionic charges of the complexes. The units in the complexes are connected together via hydrogen bonding to form 3D supramolecular networks. The supramolecular structures of 1-2 show alternating and motif linking the anionic moieties which are in turn interwoven with cationic moieties, while 3 shows alternating and motif. The magnetic properties of 1-3 are investigated and discussed in detail. 相似文献
7.
Damián Fernández 《Inorganica chimica acta》2005,358(9):2575-2584
The distorted square-planar complexes [Pd(PNHP)Cl]Cl (1) (PNHP = bis[2-(diphenylphosphino)ethyl]amine), [M(P3)Cl]Cl [P3 = bis[2-(diphenylphosphino)ethyl]phenylphosphine; M = Pd (2), Pt (3)] and [Pt(NP3)Cl]Cl (5) (NP3 = tris[2-(diphenylphosphino)ethyl]amine), coexisting in the later case with a square-pyramidal arrangement, react with one equivalent of CuCl to give the mononuclear heteroionic systems [M(L)Cl](CuCl2) [L = PNHP, M = Pd (1a); L = P3, M = Pd (2a), Pt (3a); L = NP3, M = Pt (5a)]. The crystal structure of 3a confirms that Pt(II) retains the distorted square-planar geometry of 3 in the cation with P3 acting as tridentate chelating ligand, the central P atom being trans to one chloride. The counter anion is a nearly linear dichlorocuprate(I) ion. However, the five-coordinate complexes [Pd(NP3)Cl]Cl (4), [M(PP3)Cl]Cl (M = Pd (6), Pt (7); PP3 = tris[2-(diphenylphosphino)ethyl] phosphine) containing three fused five-membered chelate rings undergo a ring-opening by interaction with one (4, 6, 7) and two (6, 7) equivalents of CuCl with formation of neutral MCu(L)Cl3 [L = NP3, M = Pd (4a); L = PP3, M = Pd (6a), Pt (7a)] and ionic [MCu(PP3)Cl2](CuCl2) [M = Pd (6b), Pt (7b)] compounds, respectively. The heteronuclear systems were shown by 31P NMR to have structures where the phosphines are acting as tridentate chelating ligands to M(II) and monodentate bridging to Cu(I). Further additions of CuCl to the neutral species 6a and 7a in a 1:1 ratio resulted in the achievement of the ionic complexes 6b and 7b with ions as counter anions. It was demonstrated that the formation of heterobimetallic or just mononuclear mixed salt complexes was clearly influenced by the polyphosphine arrangement with the tripodal ligands giving the former compounds. However, complexes [M(NP3)Cl]Cl constitute one exception and the type of reaction undergone versus CuCl is a function of the d8 metal centre. 相似文献
8.
《Inorganica chimica acta》2010,363(13):3302-8934
The reactions of L1-3Li salts containing different Y,C,Y-chelating ligands L1 = 2,6-(t-BuOCH2)2C6, L2 = 2,6-(MesOCH2)2C6 and L3 = 2,6-(Me2NCH2)2C6 with PCl3 is reported. While the presence of ligands L2,3 afforded the synthesis of dichlorophosphines L2PCl2 (2) and L3PCl2 (3), the use of ligand L1 resulted to the isolation of O → P coordinated 1-chloro-7-(t-butoxymethyl)-3H-2,1-benzoxaphosphole (1) as the result of the cyclization type reaction of dichlorophosphines L1PCl2. The hydrolysis of compounds 1-3 as well as the preparation of phosphanes L2PH2 (7), L3PH2 (8), L2PH(SnMe3) (9) and L3PH(SnMe3) (10) is also discussed. The presence of N → P coordination enabled the isolation of N → P coordinated diselenoxophosphorane L3PSe2 (11). Compounds 1-11 were characterized by the help of multinuclear NMR spectroscopy, ESI mass spectrometry and the structure of compound 11 was established by X-ray diffraction analysis. 相似文献
9.
Five new lanthanide complexes Ln(HL)3(H2O)5 · 3H2O (H2L = 5-carboxy-1-carboxymethyl-2-oxidopyridinium, Ln = La (1), Sm (2), Eu (3),Tb (4), Dy (5)) have been synthesized and characterized by elemental analyses, FT-IR spectra and X-ray single crystal diffraction. All crystals are isostructural and crystallize in the triclinic space group . The metal center is nine-coordinated completely by two phenol O atoms, two chelating carboxylic O atoms from three HL ligands and five water molecules with a distorted tri-capped trigonal prismatic geometry. Photoluminescence studies revealed that complexes 2-4 exhibit strong fluorescent emission bands in the solid state at room temperature. The transition intensity varies in the order of Tb3+ > Dy3+ > Eu3+ > Sm3+. 相似文献
10.
The ligand 1,3-bis[3-(2-pyridyl)pyrazol-1-yl]propane (L8) has afforded six-coordinate monomeric and dimeric complexes [(L8)CoII(H2O)2][ClO4]2 (1), [(L8)NiII(MeCN)2][BPh4]2 (2), [(L8)NiII(O2CMe)][BPh4] (3), and . The crystal structures of 1, 2 · MeCN, 3, and 4 revealed that the ligand L8 is flexible enough to expand its coordinating ability by fine-tuning the angle between the chelating fragments and hence folds around cobalt(II)/nickel(II) centers to act as a tetradentate chelate, allowing additional coordination by two trans-H2O, cis-MeCN, and a bidentate acetate affording examples of distorted octahedral , , and coordination. The angles between the two CoN2/NiN2 planes span a wide range 23.539(1)° (1), 76.934(8)° (2), and 69.874(14)° (3). In contrast, complex 4 is a bis-μ-1,3-acetato-bridged (syn-anti coordination mode) dicobalt(II) complex [Co?Co separation: 4.797(8) Å] in which L8 provides terminal bidentate pyridylpyrazole coordination to each cobalt(II) center. To our knowledge, this report provides first examples of such a coordination versatility of L8. Absorption spectral studies (MeCN solution) have been done for all the complexes. Complexes 1-3 are uniformly high-spin. Temperature-dependent (2-300 K) magnetic studies on 4 reveal weak ferromagnetic exchange coupling between two cobalt(II) (S = 3/2) ions. The best-fit parameters obtained are: Δ (axial splitting parameter) = −765(5) cm−1, λ (spin-orbit coupling) = −120(3) cm−1, k (orbital reduction factor) = 0.93, and J (magnetic exchange coupling constant) = +1.60(2) m−1. 相似文献
11.
Ina Trapp 《Inorganica chimica acta》2011,374(1):373-384
A new tris(pyridylhydrazonyl)methane ligand, HC[N(Me)NC(H)Py]3 (L2) (Py = pyridyl), has been synthesized. The latter is accessible from triethyl orthoformate and 2-(2-methylhydrazono)methylpyridine in 63% isolated yield. We have investigated its coordination chemistry towards copper ions and compared the results with those obtained for the recently developed multifunctional ligand, (S)P[N(Me)NC(H)Py]3 (L1). The copper(II) complexes [Cu(L1)](OTf)2 (3) and [Cu(L2)](OTf)2 (4) (OTf = triflate, (O3SCF3)−) are mononuclear with the cations coordinated by three imino and three pyridine nitrogen atoms. Almost axial symmetric EPR spectra have been obtained in frozen solutions at X-band. The spectra show resolved hyperfine couplings to the copper nuclei on one of the three g values. X-ray structural analyses revealed in each case a cis bond distortion and a trigonal twist due to Jahn-Teller effects. The CuII/CuI reduction potentials of 3 and 4 were shown to be remarkably low ( = −0.11 V for 3; = −0.34 V for 4), especially for 3 consisting of the phosphorus supported ligand L1. The corresponding copper(I) complexes [Cu(L1)](OTf) (5) and [Cu(L2)](OTf) (6) are accessible by reduction using decamethyl ferrocene. Both copper(I) complexes have been characterized in detail including X-ray structure analyses. 相似文献
12.
Vitalina M. Nikitina Vladimir N. Kokozay Roman I. Zubatyuk Oleg V. Shishkin Carlos J. Gómez-García Julia Jezierska 《Inorganica chimica acta》2009,362(7):2237-16
Three novel heterometallic complexes [Cu(en)2Cr(NCS)4(NH3)2][Cr(NCS)4(NH3)2] · 6dmf (1), [Cu(en)2Cr(NCS)4(NH3)2](OAc) (2) and [{Cu(en)2}3{Cr(NCS)4(NH3)2}2(NCS)2](NCS)2 (3) have been synthesized in a one-pot reaction from copper powder, Reineckes salt, NH4X [X− = OAc− (2), NCS− (3)] in a dmf (1) or CH3CN (2, 3) solution of ethylenediamine (en). X-ray studies showed that 1 and 2 consist of cationic polymeric chains, formed by and building blocks that bridged through thiocyanate anions. In both complexes, distinct hydrogen bonds are present and serve to increase the dimensionality of the compound from one to two (in 1) or three (in 2). The main structural feature of 3 is the pentanuclear Cu3Cr2 cation which is H-bonded with uncoordinated thiocyanate groups generating a 3D supramolecular assembly. The shortest Cu?Cr distances are 5.840(1) Å for 1, 5.856(1) and 6.018(3) Å for 2 and 6.009(9) and 6.465(9) Å for 3. Compounds 1 and 2 are essentially paramagnets whereas compound 3 shows a weak antiferromagnetic coupling. The magnetic properties are simulated and discussed in terms of the structural features. 相似文献
13.
Danielle Cangussu Humberto O. Stumpf Jim A. Thomas Miguel Julve 《Inorganica chimica acta》2005,358(7):2292-2302
The preparation and magnetic properties of three copper(II) compounds of formulae [Cu2(bpcam)2(H2O)2(C2O4)] (1), [Cu2(bpcam)2(H2O)4(C4O4)] · 10 H2O (2) and Cu2(bpcam)2(C5O5)(H2O)3 (3) [bpcam = bis(2-pyrimidyl)amidate, and are reported. The structures of two of them (1 and 2) have been solved by single crystal X-ray diffraction and consists of centrosymmetric discrete copper(II) dinuclear units bridged by bis-bidentate oxalate (1) and bis-monodentate squarate (2), with the bpcam group acting as a terminal tridentate ligand. Each copper atom in 1 exhibits a distorted elongated octahedral coordination geometry. Three bpcam nitrogen atoms and one oxalate oxygen define the basal plane while the other oxalate oxygen and a water molecule take up the axial positions. Each copper atom in 2 is in an elongated octahedral surrounding with three bpcam nitrogen atoms and one squarate oxygen in the equatorial plane and two water molecules in the axial positions. The intramolecular copper-copper separations are 5.677(1) (1) and 7.819(53) Å (2). Magnetic susceptibility measurements for 1-3 in the temperature range 1.9-290 K show the occurrence of weak ferromagnetic interactions through oxalato (J = +0.75 cm−1) and squarato (J = +1.26 cm−1), the Hamiltonian being defined by . These values are analyzed and discussed in the light of the available magneto-structural data for analogous systems. The quasi-Curie law observed in 3 (θ = −1.15 K) contrasts with the significant antiferromagnetic interaction through bis-chelating croconate in other structurally characterized croconate-bridged copper(II) complexes and rules out the presence of bridging croconate in this compound. 相似文献
14.
Hai-Bing Xu 《Inorganica chimica acta》2007,360(1):163-169
Incorporation of diplatinum component [Pt2(μ-dppm)2(CCbpy)4] (1, dppm = Ph2PCH2PPh2, CCbpy = 2,2′-dipyridyl-5-acetylide) with Re(CO)5Cl, Ru(bpy)2Cl2 (bpy = 2,2′-bipyridine) and Gd(hfac)3(H2O)2 (Hhfac = hexafluoroacetylacetone) via 2,2′-dipyridyl chelating induced isolation of (2), (3), and (4) complexes, respectively. The structures of 2 and 4 were determined by X-ray single crystal diffraction. Intense low-energy absorptions occur in the range 360-510 nm originating from metal-to-ligand charge transfer (MLCT) transitions. These compounds display photoluminescence in both solid states and dichloromethane at room temperature with emissive lifetimes in the range of microseconds. 相似文献
15.
Qi Shuai 《Inorganica chimica acta》2007,360(5):1381-1387
Three novel coordination polymers [Ca(5-OH-BDC)(H2O)3] · H2O (1), [Sr(5-OH-BDC)(H2O)4] · H2O (2) and [Ba(5-OH-BDC)(H2O)3] (3) were obtained by self-assembly of the corresponding alkaline earth metal chlorate with a ligand, 5-hydroxyisophthalic acid (5-OH-H2BDC), and their structures were determined by X-ray crystallography. The results revealed that complexes 1, 2 and 3 have two-dimensional network with (6, 3) topology observed in the bc plane. Moreover, the two-dimensional layers can be assembled into three-dimensional supramolecular architectures via intermolecular hydrogen bonds. The two carboxylate groups of 5-OH-BDC2− ligand adopt the same coordination mode in complex 1 as that in 2: a μ3-η2:η1 mode and a chelated mode while in complex 3 they coordinate to Ba(II) ions in a μ3-η2:η1 mode and a monodentate mode, which is not observed in previous reports. The constant-volume combustion energies, ΔcU, of these complexes were determined by a precise rotating-bomb calorimeter at 298.15 K, then their standard enthalpies of combustion, , and the standard enthalpies of formation, , have been calculated. 相似文献
16.
Andrew D. Garrett 《Inorganica chimica acta》2008,361(11):3135-3148
Reaction of [Tp′W(CO)2(PhCCPh)][OTf] (1b) (Tp′ = hydridotris(3,5-dimethylpyrazolyl)borate) with excess aziridine or 2-methylaziridine followed by protonation with produces chiral tungsten(II) amine complexes (3, 4; R = Me, Ph). An azetidine amido complex, Tp′W(CO)(PhCCMe)(H2) (5) is synthesized by reaction of [Tp′W(CO)2(PhCCMe)][OTf] (1a) with excess azetidine. Oxidation of amido complex 5 with I2 in the presence of a weak base provides the corresponding 1-azetine complex, (6). Addition of methylmagnesium bromide to complex 6 results in formation of predominantly one diastereomer (SWRC/RWSC) (96:4 dr) of the 2-methylazetidine complex, Tp′W(CO)(PhCCMe)(H2) (7). Reaction of complex 5 with results in formation of a cationic azetidine complex, (8). Reaction of 1b with excess piperidine followed by oxidation affords 2,3,4,5-tetrahydropyridine complex 9b, . Formation of an enamido complex, Tp′W(CO)(PhCCPh)(H2) (10), is observed upon addition of base to 9b. Subsequent addition of [D+] to the enamido β-carbon results in the formation of the deuterated product, 9b-d1, as determined by 2H NMR. Seven X-ray crystal structures have been determined, and these encompass complexes with 3, 4, and 6-membered heterocyclic ligands. Crystal structures are reported for two aziridine adducts (2, 4) two neutral amido complexes (5, 7), one cationic imine complex (6), and one cationic amine (8) complex derived from azetidine, and the imine complex formed from piperidine (9). 相似文献
17.
Chih Yuen Chen 《Inorganica chimica acta》2007,360(1):21-30
The synthesis and characterization of three simple 1:2 silver(I) pyridine adducts of different counter-anions, [Ag(py)2]+ · X− (X = ClO4, 1; BF4, 2; PF6, 3), are reported. The structural studies for 1-3 reveal the presence of strong ligand-unsupported argentophilic interactions between [Ag(py)2]+ ions, forming pairs of . The Ag?Ag contact distances are 2.96-3.00 Å. In 1 and 2, pairs of are further linked into 1-D infinite chains by a combined set of multiple Ag?Ag close contacts (3.34-3.37 Å), offset ‘head to head’ π-π stacking, and anion bridging interactions. Such combined set of interactions is anion-dependant with 1 and 2 containing anions of tetrahedral geometry and , affording essentially the same supramolecular architecture. Metal-anion interactions are crucial in organizing the 1-D chains into 3-D networks. The ES-MS studies of 1 and 2 provide positive evidence for the aggregation of silver(I) ions in solution. In contrast, for 3 with the counter-anion of octahedral , pairs of are organized into a 3-D network via a combined set of Ag?F contacts, C(H)?F hydrogen bonds, and ‘head to tail’ π-π stacking interactions. No extended 1-D polymeric chains of silver ions are present in 3. 相似文献
18.
The ethyl analogues of mesitylcopper and mesitylsilver, 2,4,6-triethylphenylcopper and 2,4,6-triethylphenylsilver, have been prepared and characterised by means of crystal structure determination. Three different compounds, [Cu4(Et3Ph)4] · 2C6H5CH3 (1), and , have thus been obtained by crystallisation from toluene or diethylether/tetrahydrofuran. All three show the square-planar metal core, most characteristic of homoleptic copper and silver aryls. The ordered (1) or disordered (2 and 3) solvent molecules are situated in the channels formed between the organometallic complexes, there being no strong directional interactions between the solvent and 2,4,6-triethylphenylcopper or 2,4,6-triethylphenylsilver. 相似文献
19.
The complex [Mn(mesalim)2Cl] (1), (Hmesalim = methyl salicylimidate) has been synthesized and fully characterized. The manganese(III) complex is formed by the reaction of the ligand Hmesalim with manganese(II) chloride. Complex 1 is mononuclear and crystallizes in the space group . Electrochemical studies were performed for complex 1, as well as for the related complexes [Mn(mesalim)2(OAc)(MeOH] · MeOH (2) and [Mn2(etsalim)4(Hetsalim)2](ClO4)2 (3), (Hetsalim = ethyl salicylimidate). The complexes display intricate oxidation-reduction behaviour, and coulometric analyses in combination with electrochemical analyses have been used to understand the electron transfer mechanisms occurring at the electrodes. 相似文献
20.
Olivier Schott Abdeslem Bentama Salah-Eddine Stiriba Jorge Pasán Marius Andruh Miguel Julve 《Inorganica chimica acta》2011,376(1):358-366
The preparation, crystal structure and variable temperature-magnetic investigation of three 2-(2′-pyridyl)imidazole-containing chromium(III) complexes of formula PPh4[Cr(pyim)(C2O4)2]·H2O (1), AsPh4[Cr(pyim)(C2O4)2]·H2O (2) and [Cr2(pyim)2(C2O4)2(OH2)2]·2pyim · 6H2O (3) [pyim = 2-(2′-pyridyl)imidazole, , and ] are reported herein. The isomorphous compounds are made up of discrete [Cr(pyim)(C2O4)2]− anions, cations [X = P (1) and As (2)] and uncoordinated water molecules. The chromium environment in 1 and 2 is distorted octahedral with Cr-N and Cr-O bond distances varying in the ranges 2.040(3)-2.101(3) and 1.941(3)-1.959(3) Å, respectively. The angle subtended by the chromium(III) ion by the two didentate oxalate ligands cover the range 82.49(12)-82.95(12)°, values which are somewhat greater than those concerning the chelating pyim molecule [77.94(13) (1) and 78.50(13)° (2)]. Complex 3 contains discrete centrosymmetric [Cr2(pyim)2(C2O4)2(OH)2] neutral units where the two chromium(III) ions are joined by a di-μ-hydroxo bridge, the oxalate and pyim groups acting as peripheral didentate ligands. Uncoordinated water and pyim molecules are also present in 3 and they contribute to the stabilization of its structure by extensive hydrogen bonding and π-π type interactions. The values of the intramolecular chromium-chromium separation and angle at the hydroxo bridge in 3 are 2.9908(12) Å and 99.60(16)°, respectively. Magnetic susceptibility measurements of 1-3 in the temperature range 1.9-300 K show the occurrence of weak inter- (1 and 2) and intramolecular (3) antiferromagnetic couplings. The magnetic properties of 3 have been interpreted in terms of a temperature-dependent exchange integral, small changes of the angle at the hydroxo bridge upon cooling being most likely responsible for this peculiar magnetic behavior. 相似文献