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Octahedral Complexes (octahedral + complex)
Selected AbstractsSyntheses and Crystal Structures of Tetrakis(arylamidine)nickel(II) Chloride and Bis[2,4-dipyridyl-1,3,5-triazapentadienato]nickel(II)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2004Jianping Guo Abstract The reaction of LiN(SiMe3)2 with arylnitrile, followed by the addition of anhydrous NiCl2 gives ionic complexes of the general formula [Ni{H2NC(Ar)=NH}4]Cl2 (Ar = Ph 1, p -tolyl 2). When the above reaction is carried out with cyanopyridine instead of arylnitrile under the same reaction conditions, neutral complexes of the general formula [{HN=C(Py)N=C(Py)NH}2Ni] (Py = 4-pyridyl, 3; 3-pyridyl, 4] are obtained. Compound 1 undergoes a metathesis reaction with sodium benzoate to give the neutral complex [(PhCO2)2Ni {H2NC(Ph)=NH}4] (5). Magnetic susceptibility measurements show that 1,4 are diamagnetic and that 5 is paramagnetic with two unpaired electrons. These results suggest that 1,4 are d8 square-planar complexes and 5 is an octahedral complex. The solid state structures of compounds 1,5 were determined by X-ray crystallography. Structural analyses reveal that 1 and 2 form a one-dimensional network through charge-assisted hydrogen bonds; whereas 5 forms a one-dimensional network through hydrogen bonds only. In complexes 3 and 4, the 2,4-dipyridyl-1,3,5-triazapentadienyl ligand behaves as a bidentate ligand forming a six-membered ring with the metal ion. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Synthesis and Crystal Structure of the Copper Complex of 7,16-Bis(2-hydroxy-5-methylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecaneCHINESE JOURNAL OF CHEMISTRY, Issue 1 2004Shu-Lan Ma Abstract A lariat crown ether ligand 7.16-bis (2-hydroxy-5-methylbenzyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (Ll) has been prepared via one-pot Mannich reaction. Its copper(II) complex Cu-Ll was synthesized and characterized by elemental analysis, IR and UV-visible spectroscopy. The crystal structure of the complex has been determined by X-ray diffraction analysis. The result shows that the copper(II) ion is six-coordinated by two nitrogen and four oxygen atoms, two from the crown ether and the other two from the deprotonated phenolate anions, forming an elongated octahedral complex. Electrochemical study indicates that the complex undergoes reversible reduction in DMF solution. [source] Synthesis, Structure and Magnetic Behaviour of Manganese(II) Selenolate Complexes ,1[Mn(SePh)2], [Mn(SePh)2(bipy)2] and [Mn(SePh)2(phen)2] (bipy = bipyridyl, phen = phenanthroline)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2007Andreas Eichhöfer Abstract The manganese selenolate complex ,1[Mn(SePh)2] has been prepared by reaction of Mn(OOCCH3)2 with 2 equiv.PhSeSiMe3 in thf. In the crystal structure, the compound forms one-dimensional chains, and the bridging selenolate ligands result in relatively short metal,metal contacts of about 3 Å. Reaction with two equivalents of the Lewis bases 2,2,-bipyridine and 1,10-phenanthroline yielded the monomeric octahedral complexes [Mn(SePh)2(2,2,-bipy)2] and [Mn(SePh)2(1,10-phen)2], respectively. The magnetic and optical properties of these complexes have been investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Stabilization of High-Valent FeIVS6 -Cores by Dithiocarbamate(1,) and 1,2-Dithiolate(2,) Ligands in Octahedral [FeIV(Et2dtc)3,n(mnt)n](n,1), Complexes (n=0, 1, 2, 3): A Spectroscopic and Density Functional Theory Computational Study,CHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2010Carsten Milsmann Dr. Abstract A detailed spectroscopic and quantum chemical analysis is presented to elucidate the electronic structures of the octahedral complexes [Fe(Et2dtc)3,n(mnt)n]n, (1,4, n=3, 2, 1, 0) and their one-electron oxidized analogues [Fe(Et2dtc)3,n(mnt)n](n,1), (1ox,4ox); (mnt)2, represents maleonitriledithiolate(2,) and (Et2dtc)1, is the diethyldithiocarbamato(1,) ligand. By using X-ray crystallography, Mössbauer spectroscopy, and Fe and S K-edge X-ray absorption spectroscopy (XAS) it is convincingly shown that, in contrast to our previous studies on [Fe(cyclam)(mnt)]1+ (cyclam=1,4,8,11-tetraazacyclotetradecane), the oxidation of 1,4 is metal-centered yielding the genuine FeIV complexes 1ox,4ox. For the latter complexes, a spin ground state of S=1 has been established by magnetic susceptibility measurements, which indicates a low-spin d4 configuration. DFT calculations at the B3LYP level support this electronic structure and exclude the presence of a ligand , radical coordinated to an intermediate-spin ferric ion. Mössbauer parameters and XAS spectra have been calculated to calibrate our computational results against the experiment. Finally, a simple ligand-field approach is presented to correlate the structural features obtained from X-ray crystallography (100,K) with the spectroscopic data. [source] Living Radical Polymerization of Acrylates Mediated by 1,3-Bis(2-pyridylimino)isoindolatocobalt(II) Complexes: Monitoring the Chain Growth at the MetalCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2008Björn Abstract A new type of mediator for cobalt(II)-mediated radical polymerization is reported which is based on 1,3-bis(2-pyridylimino)isoindolate (bpi) as ancillary ligand. The modular synthesis of the bis(pyridylimino)isoindoles (bpiH) employed in this work is based on the condensation of 2-aminopyridines with phthalodinitriles. Reaction of the bpiH protio-ligands with a twofold excess of cobalt(II) acetate or cobalt(II) acetylacetonate in methanol gave [Co(bpi)(OAc)], which crystallize as coordination polymers, and a series of [Co(acac)(bpi)(MeOH)], which are mononuclear octahedral complexes. Upon heating the [Co(acac)(bpi)(MeOH)] compounds to 100,°C under high vacuum, the coordinated methanol was removed to give the five-coordinate complexes [Co(acac)(bpi)]. The polymerization of methyl acrylate at 60,°C was investigated by using one molar equivalent of the relatively short-lived radical source 2,2,-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70) as initiator (monomer/catalyst/V-70: 600:1:1). The low solubility of the acetato complexes inhibits their significant activity as mediators in this reaction, whereas the acetylacetonate complexes control the radical polymerization of methyl acrylate more effectively. The radical polymerizations of the hexacoordinate complexes did not show a linear increase in number-average molecular weight (Mn) with conversion; however, the polydispersities were relatively low (PDI=1.12,1.40). By using the pentacoordinate complexes [Co(acac)(bpi)] as mediators, a linear increase in Mn values with conversion, which were very close to the theoretical values for living systems, and very low polydispersities (PDI<1.13) were obtained. This was also achieved in the block copolymerization of methyl acrylate and n -butyl acrylate. The intermediates with the growing acrylate polymer radical (.PA) were identified by liquid injection field desorption/ionization mass spectrometry as following the general formula [Co(acac)(4-methoxy-bpi)-(MA)n -R] (MA: methyl acrylate; R: C(CH3)(CH2C(CH3)2OCH3)CN), a notion also confirmed by NMR end-group analysis. [source] | ||||||||||