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Salen
Terms modified by Salen Selected AbstractsSynthesis and Electrochemical Study of an Original Copper(II)-Capped Salen,Cyclodextrin ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2010Elise Deunf Abstract A new metallocapped cyclodextrin (CD) was synthesized by the regioselective debenzylation, induced by diisobutylaluminium hydride (DIBAL-H), of perbenzylated cyclodextrins. This reaction allowed for the efficient preparation of an unprecedented CD,salen type copper(II) complex. The electrochemical behavior of both the bound and unbound CD,salen compounds was investigated by cyclic voltammetry. Notably, it was shown that the presence of tert -butyl groups at the ortho - and para -positions of the salen aromatic rings stabilized the copper(II) phenoxyl radical species that was generated upon the one-electron oxidation of the starting compound. Importantly, this stabilization remained effective when the salen-type ligand was covalently attached to the CD. This allowed for investigations of the reactivity of the copper(II) phenoxyl radical complex towards a primary alcohol to be performed by cyclic voltammetry. This reaction can be considered as mimicking the behavior of galactose oxidase. However, under these conditions, no reactivity was observed in the presence of benzyl alcohol. This may be due to distortion, either of the initially square planar salen ligand after its grafting to the CD primary face, and/or of the CD itself. On the other hand, the electrochemical reduction of the un-grafted copper(II) salen-type ligand led to a transient anionic species that exhibited significant stability on the time-scale of the slow cyclic voltammetry measurement in the absence of the CD, but was unstable in the presence of the CD. In the latter case, it was demonstrated that the anionic species was protonated by the CD. Importantly, this protonation was not fast enough to prevent catalytic activation of iodomethane by the electro-generated copper(I)-capped salen CD complex. [source] Photophysical and Energy-Transfer Properties of (Salen)zinc Complexes and Supramolecular AssembliesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2003Kathryn E. Splan Abstract The absorption, emission, and energy-transfer properties of monomeric and supramolecular (salen)Zn complexes (square and rectangular assemblies) are reported. The monomeric complexes fluoresce in solution, displaying photophysical behavior similar to typical (porphyrin)zinc complexes. Rhenium coordination chemistry is used to assemble molecular rectangles and squares that largely retain the photophysical properties of the parent compounds. Host-guest assemblies obtained by binding a fifth (salen)Zn complex to a tetrakis(salen) square are capable of efficient salen-to-salen electronic energy transfer. Energy transfer flow through these systems can be manipulated by modification of the salen building-block structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Novel Chiral (Salen)MnIII Complexes Containing a Calix[4]arene Unit as Catalysts for Enantioselective Epoxidation Reactions of (Z)-Aryl AlkenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2005Maria E. Amato Abstract New asymmetric (salen)MnIII and UO2 complexes containing a calix[4]arene unit in the ligand framework were synthesized. The UO2 complexes were characterized by 1H-, 13C-, 2D TOCSY and T-ROESY NMR spectroscopy. Furthermore, the structure of one UO2 complex was determined by single-crystal X-ray analysis. The data showed that UO2 complexes, which can be considered in first approximation models of the Mn=O oxidant active species, possess a chiral pocket and adopt relevant conformations for the selectivity of the oxygen transfer process. Epoxidation data of model alkenes with the MnIII complexes showed moderate ee values and were not conclusive in indicating that the calix[4]arene unit might be able to influence the selectivity by a molecular recognition mechanism. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Enhanced Cooperativity in Hydrolytic Kinetic Resolution of Epoxides using Poly(styrene) Resin-Supported Dendronized Co-(Salen) CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2008Poorva Goyal Abstract Excellent enantioselectivities and isolated yields have been achieved for the hydrolytic kinetic resolution of epoxides using a resin-supported dendronized R,R-(salen)Co catalyst with catalyst loadings as low as 0.04 mol%, the lowest metal loadings of any heterogeneous resin-supported (salen)Co catalyst reported to date. In addition, the supported catalysts can be recycled and reused with comparable enantioselectivities. It is hypothesized that the high catalytic activity can be attributed to the flexible linker and the dendronized framework supporting the (salen)Co moieties on the resin thereby promoting cooperativity between two metal centers. This work opens up new opportunities for the design of highly active resin-supported catalysts that catalyze transformations through a bimetallic pathway. [source] Discrete versus In Situ -Generated Aluminum-Salen Catalysts in Enantioselective Cyanosilylation of Ketones: Role of Achiral LigandsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2008Ali Alaaeddine Abstract The monometallic species {Salen}AlX (X=Me, 2a,b; X=Cl, 4a,b; O- i- Pr, 5a,b) and open bimetallic species {Salen}[AlMe2]2 (3a,b) that result from binary combinations between an aluminum precursor [trimethylaluminum, dimethylaluminum chloride, aluminum tris(isopropoxide)] and a diprotio {Salen}H2 pro-ligand 1a,b (a=1R,2R -cyclohexyl-salen; b=1R,2R -diphenylethylene-salen) have been isolated. The crystal structures of 3b, 4b and of ,-oxo species [{diphenylethylene-salen}Al]2O (6b) are reported. The discrete species 2,5a,b have been individually evaluated in the asymmetric cyanosilylation of acetophenone. It is shown that, in several cases, these discrete catalysts display dramatically different performances than the catalyst systems in situ -generated from the binary combinations. The influence of the achiral ligand X on both the enantioselectivity and activity of the cyanosilylation reaction has been investigated, resulting in the definition of a highly active and productive hexafluoro-2-propoxide-based catalyst for a variety of aryl alkyl ketones (TON up to 470, TOF up to 140,h,1 at ,20,°C for acetophenone). [source] Innentitelbild: Stable Pentavalent Uranyl Species and Selective Assembly of a Polymetallic Mixed-Valent Uranyl Complex by Cation,Cation Interactions (Angew. Chem.ANGEWANDTE CHEMIE, Issue 45 200945/2009) Oligomere Komplexe mit kationischen Actinyleinheiten sind entscheidend für die Aufarbeitung von radioaktivem Abfall und die Verteilung von Actinoiden in der Umwelt. In ihrer Zuschrift auf S.,8629,ff. zeigen M. Mazzanti et,al., dass der N,N,-Bis(salicyliden)ethylendiamin-Ligand (Salen) fünfwertiges Uran stabilisieren kann. Ein entsprechender Vierkernkomplex, in dem eine antiferromagnetische Kopplung zwischen den vier oxoverbrückten Uranzentren vorliegt, ist stabil gegen Disproportionierung und Hydrolyse. [source] ChemInform Abstract: Salen and Half-Salen Palladium(II) Complexes: Synthesis, Characterization and Catalytic Activity Toward Suzuki,Miyaura Reaction.CHEMINFORM, Issue 22 2010Ping Liu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Enantioselective Iodolactonizations of 4-Pentenoic Acid Derivatives Mediated by Chiral Salen,Co(II) Complex.CHEMINFORM, Issue 3 2010Zhaolun Ning Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Highly Enantioselective Carbonyl-ene Reactions Catalyzed by a Hindered Silyl,Salen,Cobalt Complex.CHEMINFORM, Issue 12 2008Gerri E. Hutson Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Axial Ligand Effects: Utilization of Chiral Sulfoxide Additives for the Induction of Asymmetry in (Salen)ruthenium(II) Olefin Cyclopropanation Catalysts.CHEMINFORM, Issue 42 2005Jason A. Miller Abstract For Abstract see ChemInform Abstract in Full Text. [source] Electrosynthesis of 2-Arylpropionic Acids from ,-Methylbenzyl Chlorides and Carbon Dioxide by [Co(Salen)].CHEMINFORM, Issue 40 2005J. Damodar Abstract For Abstract see ChemInform Abstract in Full Text. [source] Highly Enantioselective Conjugate Additions to ,,,-Unsaturated Ketones Catalyzed by a (Salen)Al Complex.CHEMINFORM, Issue 22 2005Mark S. Taylor Abstract For Abstract see ChemInform Abstract in Full Text. [source] Highly Enantioselective Conjugate Additions to ,,,-Unsaturated Ketones Catalyzed by a (Salen)Al Complex.CHEMINFORM, Issue 22 2005Mark S. Taylor Abstract For Abstract see ChemInform Abstract in Full Text. [source] The Enantioselective High-Pressure Diels,Alder Reaction of 1-Methoxybuta-1,3-diene with tert-Butyldimethylsilyloxyacetaldehyde Catalyzed by (Salen)Co(II) and (Salen)Cr(III)Cl Complexes.CHEMINFORM, Issue 3 2005Malgorzata Malinowska No abstract is available for this article. [source] Enantioselective Alkynylation of Ketones Catalyzed by Zn(Salen) Complexes.CHEMINFORM, Issue 42 2003Pier Giorgio Cozzi Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Asymmetric Epoxidation Using a Singly-Bound Supported Katsuki-Type (Salen)Mn Complex.CHEMINFORM, Issue 30 2002Keith Smith Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Mn(Salen)-Catalyzed Enantioselective C,H Amination.CHEMINFORM, Issue 32 2001Yoshinori Kohmura Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Substituted Salen,Ru(II) Complexes as Catalysts in the Asymmetric Cyclopropanation of Styrene by Ethyl Diazoacetate: The Influence of Substituents and Achiral Additives on Activity and Enantioselectivity.CHEMINFORM, Issue 27 2001Xiaoquan Yao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Cobalt(II) salen complex with two aza-crown pendants and its analogues as synthetic oxygen carriersCHINESE JOURNAL OF CHEMISTRY, Issue 6 2004Xing-Yue Wei Abstract Salen with two aza-crown ether pendants H2L1 and its analogues H2L2- H2L4 were successfully synthesized starting from benzo-10-aza-15crown-5 (BN15C5) or morpholine. Their structures were characterized by IR, MS, 1H NMR and elemental analysis, and were confirmed by X-ray diffraction analysis of H2L1. Moreover, the saturated oxygen uptake of their cobalt(II) complexes CoL1- CoL4 in diethyleneglycol dimethyl ether was determined at different temperature. The oxygenation contants (KO2 ) and thermodynamic parameters (,H° and ,S°) were calculated. The modulation of O2 -binding capabilities by pendant substituents were investigated as compared with the parent Schiff base complex CoL5 (CoSalen). The results indicate that the dioxygen affinities of CoL have been much more enhanced by aza-crown pendants than that by morpholino pendants, and the O2 -binding capabilities of CoL1 and CoL2 with aza-crown pendants would also be enhanced by adding alkali metal cations. [source] Cobalt(II) Complexes with Substituted Salen-Type Ligands and Their Dioxygen Affinity in N,N -Dimethylformamide at Various TemperaturesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2005Andreas Huber Abstract Several unsymmetrically substituted salen-type cobalt(II) Schiff-base complexes CoL [H2L = 1,6-bis(2-hydroxyphenyl)-3,3-dimethyl-2,5-diaza-1,5-hexadiene (1); 1,6-bis(2-hydroxyphenyl)-3,3-dimethyl-2,5-diaza-1,5-heptadiene (2); 1-(3- tert -butyl-2-hydroxy-5-methylphenyl)-6-(2-hydroxyphen-yl)-3,3-dimethyl-2,5-diaza-1,5-heptadiene (3); 1-(2-hydroxyphenyl)-6-methyl-2,5-diaza-1,5-nonadien-8-one (4); 1-(3- tert -butyl-2-hydroxy-5-methylphenyl)-6-methyl-2,5-di-aza-1,5-nonadien-8-one (5); 1-(2-hydroxyphenyl)-3,3,6-trimethyl-2,5-diaza-1,5-nonadien-8-one (6); 1-(3- tert -butyl-2-hydroxy-5-methylphenyl)-3,3,6-trimethyl-2,5-diaza-1,5-nonadien-8-one (7)] were prepared and characterized by their UV/Vis absorption spectra, magnetic moments, and oxidation potentials. Except for complex 4 (irreversible oxidation with t½ , 3 h), complexes 1,3 and 5,7 are remarkably resistant against irreversible auto-oxidation in air-saturated N,N -dimethylformamide (DMF) at ambient temperature. To characterize the Lewis acidity of the cobalt center in 1,7, the equilibrium constant Kpy was determined for monoadduct formation with pyridine (CoL + pyCoL·py). An O2 -sensitive optode was used to determine the Henry constant, KH, for the system O2/DMF in the temperature range 298,228 K. The formation of 1:1 adducts of complexes 1,7 with O2 in DMF, as characterized by the equilibrium constant K, was followed spectrophotometrically in the temperature range 298,228 K. The parameters ,Ho, ,So, and K are reported. At 298 K, K ranges from 21.9 M,1 (5) to 155 M,1 (7). The overall spectroscopic information, including EPR spectra obtained with frozen solutions of 3 and 7 in O2 -saturated DMF, confirm that the 1:1 adducts CoL·O2 are cobalt(III) superoxo compounds. The symmetrically substituted salen complex8 [H2L = 1,6-bis(3- tert -butyl-2-hydroxy-5-methylphenyl)-3,3,4,4-tetramethyl-2,5-diaza-1,5-hexadiene in 8] is shown to catalyze the oxidation of triphenylphosphane and 2,6-di- tert -butylphenol by O2 in DMF at ambient temperature. The correlation of the data obtained for K, Kpy, and the oxidation potential E½ is discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Photophysical and Energy-Transfer Properties of (Salen)zinc Complexes and Supramolecular AssembliesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2003Kathryn E. Splan Abstract The absorption, emission, and energy-transfer properties of monomeric and supramolecular (salen)Zn complexes (square and rectangular assemblies) are reported. The monomeric complexes fluoresce in solution, displaying photophysical behavior similar to typical (porphyrin)zinc complexes. Rhenium coordination chemistry is used to assemble molecular rectangles and squares that largely retain the photophysical properties of the parent compounds. Host-guest assemblies obtained by binding a fifth (salen)Zn complex to a tetrakis(salen) square are capable of efficient salen-to-salen electronic energy transfer. Energy transfer flow through these systems can be manipulated by modification of the salen building-block structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Resolution of Racemic N -Benzyl ,-Amino Acids by Liquid-Liquid Extraction: A Practical Method Using a Lipophilic Chiral Cobalt(III) Salen Complex and Mechanistic StudiesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2008Pawel Dzygiel Abstract The efficient resolution of racemic N -benzyl ,-amino acids (N -Bn-AA) has been achieved by a liquid-liquid extraction process using the lipophilic chiral salen,cobalt(III) complex [CoIII(3)(OAc)]. As a result of the resolution by extraction, one enantiomer (S) of the N -benzyl ,-amino acid predominated in the aqueous phase, while the other enantiomer (R) was driven into the organic phase by complexation to cobalt. The complexed amino acid (R) was then quantitatively released by a reductive (CoIII,,,CoII) counter-extraction with aqueous sodium dithionite or L -ascorbic acid in methanol. Thereductive cleavage allowed to recover the [CoII(3)] complex in good yield, which could be easily re-oxidized to[CoIII(3)(OAc)] with air/AcOH and reused with essentially no loss of reactivity and selectivity. Investigation on the nitrogen substitution indicates that the presence of a single benzyl group on the amino acid nitrogen is important to obtain high enantioselectivity in the extraction process. The kinetic vs. thermodynamic nature of the resolution process was also investigated with an enantiomeric exchange experiment, which shows that the liquid-liquid extraction with [CoIII(3)(OAc)] is an equilibrium process operating under thermodynamic control. In the absence of a suitable crystal structure of the [CoIII(3)(N -Bn-AA)] complexes, computational and spectroscopic studies were used to investigate how the N -benzyl ,-amino acids are accommodated in the "binding pocket" of the chiral cobalt complex. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Novel Chiral (Salen)MnIII Complexes Containing a Calix[4]arene Unit as Catalysts for Enantioselective Epoxidation Reactions of (Z)-Aryl AlkenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2005Maria E. Amato Abstract New asymmetric (salen)MnIII and UO2 complexes containing a calix[4]arene unit in the ligand framework were synthesized. The UO2 complexes were characterized by 1H-, 13C-, 2D TOCSY and T-ROESY NMR spectroscopy. Furthermore, the structure of one UO2 complex was determined by single-crystal X-ray analysis. The data showed that UO2 complexes, which can be considered in first approximation models of the Mn=O oxidant active species, possess a chiral pocket and adopt relevant conformations for the selectivity of the oxygen transfer process. Epoxidation data of model alkenes with the MnIII complexes showed moderate ee values and were not conclusive in indicating that the calix[4]arene unit might be able to influence the selectivity by a molecular recognition mechanism. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Enantioselective Synthesis of , -Blockers via Hydrolytic Kinetic Resolution of Terminal Oxiranes by Using Bimetallic Chiral {{2,2,-[Cyclohexane-1,2-diylbis(nitrilomethylidyne)]bis[phenolato]}(2,)}cobalt ([Co(salen)])-Type ComplexesHELVETICA CHIMICA ACTA, Issue 2 2008Rahul Abstract The synthesis of chirally pure , -blockers was successfully achieved via hydrolytic kinetic resolution of butyl (±)-4-(oxiran-2-ylmethoxy)benzeneacetate ((±)- 1) and (±)-4-(oxiran-2-ylmethoxy)benzeneacetonitrile ((±)- 2) in the presence of bimetallic chiral [Co(salen)]-type complexes. The newly synthesized bimetallic chiral [Co(salen)]-type complexes exhibited excellent enantioselectivities of up to >98% ee in good yields (Tables,1,3). [source] Enhanced Cooperativity in Hydrolytic Kinetic Resolution of Epoxides using Poly(styrene) Resin-Supported Dendronized Co-(Salen) CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2008Poorva Goyal Abstract Excellent enantioselectivities and isolated yields have been achieved for the hydrolytic kinetic resolution of epoxides using a resin-supported dendronized R,R-(salen)Co catalyst with catalyst loadings as low as 0.04 mol%, the lowest metal loadings of any heterogeneous resin-supported (salen)Co catalyst reported to date. In addition, the supported catalysts can be recycled and reused with comparable enantioselectivities. It is hypothesized that the high catalytic activity can be attributed to the flexible linker and the dendronized framework supporting the (salen)Co moieties on the resin thereby promoting cooperativity between two metal centers. This work opens up new opportunities for the design of highly active resin-supported catalysts that catalyze transformations through a bimetallic pathway. [source] Cooperative Catalysis in the Hydrolytic Kinetic Resolution of Epoxides by Chiral [(salen)Co(III)] Complexes Immobilized on Gold ColloidsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2008Thomas Belser Abstract Chiral salen ligands were incorporated into self-assembled thiolate monolayers (SAMs) on gold colloids. Treatment of the immobilized ligand with Co(OAc)2,4,H2O yielded the corresponding [(salen)Co(II)] complex, and aerobic oxidation in the presence of triflic acid afforded the catalytically active [(salen)Co(III)] complex. Functionalized gold colloids with a diameter of 3.4,nm, coated with a mixed monolayer of n -octanethiolates and thiolates with chiral [(salen)Co(III)] end groups were studied as catalysts in the hydrolytic kinetic resolution (HKR) of hexene-1-oxide. Extremely high selectivitiy and significant rate acceleration relative to homogeneous monomeric catalysts were observed. Recovery of the immobilized catalyst was accomplished by simple filtration, and catalyst reoxidation and repeated recycling (seven times) was possible with no loss of reactivity or enantioselectivity. [source] Near-stoichiometric O2 binding on metal centers in Co(salen) nanoparticlesAICHE JOURNAL, Issue 4 2009Chad Johnson Abstract Co(salen) [cobaltous bis(salicylaldehyde)ethylenediamine] complexes are well-known O2 carriers in solution. In the solid phase, these complexes exhibit some O2 binding but detailed studies have been complicated because few of the known polymorphs of Co(salen) actually bind O2. The O2 binding results for nanoparticulate Co(salen) are presented in this study. Rod-shaped Co(salen) nanoparticles, roughly 100 nm in diameter, were recrystallized by spraying a methylene chloride solution of commercially obtained Co(salen) into supercritical carbon dioxide. Temperature-programmed desorption, thermogravimetric analysis, and a Rubotherm magnetic suspension balance measurements reveal a reversible O2 uptake of ,1.51 mmol/(g nanoparticles) at 25°C, consistent with a binding stoichiometry involving a bridging peroxo unit between two Co centers. In contrast, no measurable O2 uptake was observed with the commercial Co(salen). These results clearly show the potential for bottom-up design of nanoparticulate metal complexes for enhanced O2 storage and other applications. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Ring-opening polymerization of substituted ,-caprolactones with a chiral (salen) AlOiPr complexJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2007Mark R. Ten Breteler Abstract The ring-opening polymerization (ROP) of ,-caprolactone (,-CL), 4-methyl-,-caprolactone (4-MeCL), and 6-methyl-,-caprolactone (6-MeCL) with a single-site chiral initiator, R,R,-(salen) aluminum isopropoxide (R,R,-[1]), was investigated. The kinetic data for the ROP of the three monomers at 90° in toluene corresponded to first-order reactions in the monomer and propagation rate constants of k,-CL > k4-MeCL , k6-MeCL. A notable stereoselectivity with a preference for the R -enantiomer was observed in the ROP of 6-MeCL with R,R,-[1], whereas for 4-MeCL, no stereoselectivity was found. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 429,436, 2007. [source] Synthesis and molecular structure of Cr(salen)(,-N)RhCl(COD): the first example of a heterobimetallic nitride-bridged complex containing chromiumACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2010Johan Vibenholt Five-coordinate Cr(N)(salen) {salen is 2,2,-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolate} reacts with [RhCl(COD)]2 (COD is 1,5-cyclooctadiene) to yield the heterobimetallic nitride-bridged title compound, namely chlorido-2,Cl -[2(,4)-1,5-cyclooctadiene]{2,2,-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato-1,4O,N,N,,O,}-,-nitrido-1:2,2N:N -chromium(V)rhodium(I), [CrRh(C16H14N2O2)ClN(C8H12)]. The Cr,N bond of 1.5936,(14),Å is elongated by only 0.035,Å compared to the terminal Cr,N bond in the precursor. The nitride bridge is close to being linear [173.03,(9)°] and the Rh,N bond of 1.9594,(14),Å is very short for a monodentate nitrogen-donor ligand, indicating significant ,-acceptor character of the Cr[triple-bond]N group. [source] Two polymorphs of aqua[N,N,-ethylenebis(salicylideneaminato- N,O)]oxovanadium(V) nitrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2001Alan Hazell The title compound, aqua[bis(salicylidene)ethylenediaminato- O,N,N,,O,]oxovanadium(V) nitrate, [VO(C16H14N2O2)(H2O)]NO3, crystallizes as two polymorphs in the triclinic and monoclinic crystal systems. In both, the V atom has a distorted octahedral coordination geometry with a long V,Owater bond trans to V=O. The coordinated water molecules are hydrogen bonded to the nitrate ions so that pairs of cations are linked to give neutral centrosymmetric dimers. The V=O and V,Owater distances are 1.598,(2) and 2.257,(2),Å, respectively, in the triclinic form, and 1.588,(3) and 2.230,(3),Å, respectively, in the monoclinic form. In the triclinic form, the dimers pack so that the salen [bis(salicylidene)ethylenediaminate] ligands are parallel to each other, whereas in the monoclinic form, which is the denser, there is a herring-bone arrangement. [source] | |||||||||||||||||||||||||