Methoxide Complexes Research Articles

Facile Conversion of CO/H2 into Methoxide at a Uranium(III) Center

The reaction of [U(-C8H6{SiiPr3-1,4}2)(-Cp*)] in toluene with CO and H2 at sub to ambient temperature and pressure affords the methoxide complex [U(-C8H6{SiiPr3-1,4}2)(-Cp*)OMe]

Structural and orthoselectivity study of 2-hydroxybenzaldehyde using spectroscopic analysis

The orthoselectivity and high yield are two significant subjects which should be studied more in the process of hydroxybenzaldehydes or salicylaldehyde production. In this work, salicylaldehyde was synthesized by the reaction of formaldehyde and phenol magnesium methoxide complex, in an anhydrous medium. In order to achieve a selectively orthoformylated product, at first the hydroxyl group of phenol was rearranged by magnesium methoxide. The phenol magnesium salt was then formylated by paraformaldehyde. Impurities of the resulted salicylaldehyde were removed by several steps of liquid extracting via water and acid washing. The spectroscopic data of FT-IR, 1H NMR (500 MHz), and GC/MS on the final product were recorded and interpreted. The results of FT-IR spectrum and integration value of 1H NMR spectrum imply on the high conversion of reaction. The GC/MS spectrum also shows that the amounts of by products are low enough.

Comparative Studies of Preferential Binding of Group Nine Metalloporphyrins (M = Co, Rh, Ir) with Methoxide/Methanol in Competition with Hydroxide/Water in Aqueous Solution

Aqueous solutions of iridium(III) tetra-(p-sulfonatophenyl)porphyrin [(TSPP)Ir(III)] form a hydrogen ion dependent equilibrium distribution of bisaquo ([(TSPP)Ir(III)(OD(2))(2)](3-)), monoaquo/monohydroxo ([(TSPP)Ir(III)(OD(2))(OD)](4-)) and bishydroxo ([(TSPP)Ir(III)(OD)(2)](5-)) complexes. Comparison of acid dissociation constants of group nine ([(TSPP)M(III)(OD(2))(2)](3-)) (M = Co, Rh, Ir) complexes show that the extent of proton dissociation in water increases regularly on moving down the group from cobalt to iridium consistent with increasing metal ligand bond strength. Addition of small quantities of methanol to aqueous solutions of [(TSPP)Ir(III)] results in the formation of methanol and methoxide complexes in equilibria with aquo and hydroxo complexes that are observed by (1)H NMR. Direct quantitative evaluation of competitive equilibria of [(TSPP)Ir(III)] complexes reveals a remarkable thermodynamic preference for methanol binding over that of water (DeltaG degrees (298 K) = -5.2 kcal mol(-1)) and methoxide binding over that of hydroxide (DeltaG degrees (298 K) = -6.1 kcal mol(-1)) in aqueous media. A comparison of equilibrium thermodynamic values for displacement of hydroxide by methoxide for group nine (TSPP)M(III) (M = Co, Rh, Ir) complexes in aqueous media are also reported.

Hydrogenolysis of Palladium(II) Hydroxide and Methoxide Pincer Complexes

Hydrogenolysis reactions of palladium(II) hydroxide and methoxide complexes to form water and methanol, respectively, and the corresponding palladium(II) hydride are reported. In the presence of water, 1 was found to exist in solution as a water-bridged dimer; however, kinetic studies suggest the reaction of 1 and H(2) proceeds exclusively through the hydroxide monomer to form the palladium(II) hydride and water. Computational studies suggest a four-center intramolecular proton transfer as opposed to an oxidative addition/reductive elimination pathway.

Structural and Spectroscopic Characterization of a Charge-Separated Uranium Benzophenone Ketyl Radical Complex

The reaction of [((t-Bu)ArO) 3tacn)U (III)] ( 1) with 4,4'-di- tert-butylbenzophenone affords a unique isolable U(IV) ketyl radical species [((t-Bu)ArO) 3tacn)U (IV)(OC* (t-Bu)Ph 2)] (2) supported by XRD data, magnetization measurements, and DFT calculations. Isolation and full characterization of the corresponding diphenyl methoxide complex [((t-Bu)ArO) 3tacn)U (IV)(OCH ( t-Bu )Ph 2)] (3) is also presented. The one-electron reduction of benzophenone by [((Ad)ArO) 3tacn)U (III)] (4) leads to a purple U(IV) ketyl radical intermediate [((Ad)ArO) 3tacn)U (IV)(OC*Ph 2)] (5). This species is highly reactive, and attempts at isolation were unsuccessful and resulted in methoxide complex [((Ad)ArO) 3tacn)U (IV)(OCHPh 2)] (6) from H abstraction and dinuclear para-coupled complex [((Ad)ArO) 3tacn)U (IV)(OCPhPhCPh 2O)U (IV)((Ad)ArO) 3tacn)] (7).

Asymmetric Aerobic Oxidation of α-Hydroxy Acid Derivatives by C4-Symmetric, Vanadate-Centered, Tetrakisvanadyl(V) Clusters Derived from N-Salicylidene-α-aminocarboxylates

A series of chiral vanadyl(V) methoxides bearing 3-t-butyl-5-substituted N-salicylene-L-valinate and L-t-leucinate as chiral auxiliaries has been prepared. In all cases except the 3,5-di-t-butyl analogue, they exist as monomers both in solution and in the single crystal state. In the case of the 3,5-di-t-butyl analogue, the architectural nature of the vanadyl(V) complex highly depends on the base used during the complex formation event. A pentanuclear C4-symmetric complex was formed when potassium salts were employed instead of the corresponding sodium salts. A central vanadate(V) unit serves to grip four identical chiral monomeric vanadyl(V) units together, by which a potassium ion sits on top of the four flanking units through carbonyl coordinations and serves to hold the whole cluster by cooperation with the central vanadate(V) unit. In comparison with the corresponding monomeric vanadyl(V) methoxide complex, the cluster complex was utilized to facilitate the asymmetric aerobic oxidations of various racemic alpha-hydroxyesters, -amides, and -thioesters with excellent selectivity factors (krel 40 to >500).

Electrophilic reactivity of the zwitterionic titanocene monohalides Cp[η 5-C 5H 4B(C 6F 5) 3]TiX (X = Cl, Br): Reactions with water and methanol

The paper reports new data evidencing for a high electrophilicity of the positively charged titanium atom in the previously described zwitterionic titanocene monochloride Cp[η 5-C 5H 4B(C 6F 5) 3]TiCl ( 1) and titanocene monobromide Cp[η 5-C 5H 4B(C 6F 5) 3]TiBr ( 2), containing a B(C 6F 5) 3 group in one of the C 5 rings. It has been established that on a contact of a toluene solution of these zwitterions with water vapour at 20 °C under Ar, a rapid protolytic cleavage of the otherwise inert B–C 6F 5 bond in the tris(pentafluorophenyl)borane moiety occurs to afford pentafluorobenzene and the corresponding halogenide hydroxide complex of titanocene Cp[η 5-C 5H 4B(C 6F 5) 2]TiX(μ-OH), where X = Cl ( 3), Br ( 4). An X-ray diffraction study of the complexes has shown that the hydroxide group in 3 and 4 is bonded via the oxygen atom both to the titanium and boron atoms. Under similar conditions, the interaction of zwitterion 1 with methanol gives rise to pentafluorobenzene and the chloride methoxide complex of titanocene Cp[η 5-C 5H 4B(C 6F 5) 2]TiCl(μ-OCH 3). It has been suggested that the driving force of the protolysis of the B–C 6F 5 bond in 1 and 2 is a sharp increase in the acidity of water or methanol molecule as a result of their complexation with the positively charged titanium centre in the starting zwitterion.

Hydrogen Atom Abstraction by a Mononuclear Ferric Hydroxide Complex: Insights into the Reactivity of Lipoxygenase

The lipoxygenase mimic [Fe(III)(PY5)(OH)](CF3SO3)2 is synthesized from the reaction of [Fe(II)(PY5)(MeCN)](CF3SO3)2 with iodosobenzene, with low-temperature studies suggesting the possible intermediacy of an Fe(IV) oxo species. The Fe(III)-OH complex is isolated and identified by a combination of solution and solid-state methods, including EPR and IR spectroscopy. [Fe(III)(PY5)(OH)](2+) reacts with weak X-H bonds in a manner consistent with hydrogen-atom abstraction. The composition of this complex allows meaningful comparisons to be made with previously reported Mn(III)-OH and Fe(III)-OMe lipoxygenase mimics. The bond dissociation energy (BDE) of the O-H bond formed upon reduction to [Fe(II)(PY5)(H2O)]2+ is estimated to be 80 kcal mol(-1), 2 kcal mol(-1) lower than that in the structurally analogous [Mn(II)(PY5)(H2O)]2+ complex, supporting the generally accepted idea that Mn(III) is the thermodynamically superior oxidant at parity of coordination sphere. The identity of the metal has a large influence on the entropy of activation for the reaction with 9,10-dihydroanthracene; [Mn(III)(PY5)(OH)]2+ has a 10 eu more negative DeltaS++ value than either [Fe(III)(PY5)(OH)]2+ or [Fe(III)(PY5)(OMe)]2+, presumably because of the increased structural reorganization that occurs upon reduction to [Mn(II)(PY5)(H2O)]2+. The greater enthalpic driving force for the reduction of Mn(III) correlates with [Mn(III)(PY5)(OH)]2+ reacting more quickly than [Fe(III)(PY5)(OH)]2+. Curiously, [Fe(III)(PY5)(OMe)]2+ reacts with substrates only about twice as fast as [Fe(III)(PY5)(OH)]2+, despite a 4 kcal mol(-1) greater enthalpic driving force for the methoxide complex.

Highly Enantioselective Aerobic Oxidation of α-Hydroxyphosphonates Catalyzed by Chiral Vanadyl(V) Methoxides Bearing N-Salicylidene-α-aminocarboxylates

An unprecedented vanadyl(V) methoxide complex 4 derived from 3,5-dibromo-N-salicylidene-l-tert-leucinate enables highly enantioselective aerobic oxidations of alpha-hydroxyphosphonates at ambient temperature with selectivity factors ranging from 3 to >99.

ChiralN-salicylidene vanadyl carboxylate-catalyzed enantioselective aerobic oxidation of α-hydroxy esters and amides

A series of chiral vanadyl carboxylates derived from N-salicylidene-L-alpha-amino acids and vanadyl sulfate has been developed. These configurationally well defined complexes were examined for the kinetic resolution of double- and mono-activated 2 degrees alcohols. The best chiral templates involve the combination of L-tert-leucine and 3,5-di-t-butyl-, 3,5-diphenyl-, or 3,4-dibromo-salicylaldehyde. The resulting vanadyl(V)-methoxide complexes after recrystallization from air-saturated methanol serve as highly enantioselective catalysts for asymmetric aerobic oxidation of alpha-hydroxyl-esters and amides with a diverse array of alpha-, O-, and N-substituents at ambient temperature in toluene. The asymmetric inductions of the oxidation process are in the range of 10 to >100 in terms of selectivity factors (k(rel)) in most instances. The previously undescribed aerobic oxidation protocol is also applicable to the kinetic resolution of C-13 taxol side chain with high selectivity factor (k(rel) = 35). X-ray crystallographic analysis of an adduct between a given vanadyl complex and N-benzyl-mandelamide allows for probing the stereochemical origin of the nearly exclusive asymmetric control in the oxidation process.

Reductive Nitrosylation and Proton-Assisted Bridge Splitting of a (μ-Oxo)dimanganese(III) Complex Derived from a Polypyridine Ligand with One Carboxamide Group

Aerobic oxidation of the Mn(II) complex [Mn(Papy3)(H2O)](ClO4) (1, PaPy3- is the anion of the designed ligand N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide) in acetonitrile affords the (mu-oxo)dimanganese(III) complex [(Mn(PaPy3))2(mu-O)](ClO4)2 (3) in high yield. The unsupported single oxo bridge between the two high-spin Mn(III) centers in 3 is readily cleaved upon addition of proton sources such as phenol, acetic acid, and benzoic acid, and complexes of the type [Mn(PaPy3)(L)](ClO4) (5, L = PhO-; 6, L = AcO-; 7, L = BzO-) are formed. The basicity of the bridge is evident by the fact that simple addition of methanol to a solution of 3 in acetonitrile affords the methoxide complex [Mn(PaPy3)(OMe)](ClO4) (4). The structures of 3-5 and 7 have been determined. Passage of NO through a solution of 3 in acetonitrile produces the [Mn-NO]6 nitrosyl [Mn(PaPy3)(NO)](ClO4) (2) via reductive nitrosylation. Complexes 4-7 also afford the [Mn-NO]6 nitrosyl 2 upon reaction with NO. In the latter case, the anionic O-based ligands (such as MeO- and PhO-) act as built-in bases and promote reductive nitrosylation of the Mn(III) complexes.

Thermal decomposition of the methoxide complexes MoO(OMe)4, Re4O6(OMe)12 and (Re1−xMox)O6(OMe)12 (0.24≤x≤0.55)

The thermal decomposition of the methoxide complexes MoO(OMe)4 (I), Re4O6(OMe)12 (II) and (Re1−xMox)O6(OMe)12 (0.24≤x≤0.55) (III) in hydrogen and nitrogen at T≤800°C and in air at temperatures T≤400°C have been monitored by thermal analysis, X-ray powder diffraction and scanning electron microscopy. Heating of I, II and III in air yields orthorhombic MoO3, ReO3 and a mixture of these two phases, respectively. Thermal treatment of I and II in nitrogen, using heating rates of 20Kmin−1 or faster, yields the same products as in air, while applying slower heating rates of I and thermal treatment of III in nitrogen yield the tetragonal modification of MoO2 and (Re1−xMox)O2 (with 0.24≤x≤0.55), respectively. Heat treatment of I, II and III in hydrogen yields fine powders of Mo, Re or a Re–Mo alloy (having the structure of the σ-phase) at surprisingly low temperatures, around 520, 240 and 360°C for I, II and III, respectively.

Mononuclear N3S(thioether)-ligated copper(II) methoxide complexes: synthesis, characterization, and hydrolytic reactivity.

Mononuclear copper(II) methoxide complexes supported by N(3)S(thioether) chelate ligands having two internal hydrogen bond donors have been prepared, comprehensively characterized, and evaluated for hydrolytic reactivity.

Mechanochemical synthesis of lanthanum chromate by grinding of constituent oxides : F. Saito et al. (Tohoku University, Sendai, Japan.) Powder Technol., Vol. 122, No 2–3, 2002, 145–149

Alkaline earth-doped LaCrO3 is a satisfactorily conducting ceramic material for the interconnector of Solid Oxide Fuel Cells (SOFC). For the synthesis of highly sinterable LaCrO3 powders spraydrying of adequate precursors like sols based on alkoxides has been used. Lanthanum chromium hydroxide sol was prepared by hydrolysis of synthesized methoxide complexes. The chemical reactions during hydrolysis and peptization of the precursors are described. The crystalline phase formation during heat treatment of spray-dried amorphous gel consisting of hydroxides and contaminant chloride ligands was characterized by thermal analysis methods (TG, DTG, DTA) and X-ray diffraction analysis. The progressive oxidation of Cr(III) by thermal dehydroxylation transforms the powder into fine crystallized La(III) Cr(V)hydroxo-oxychloride at 450 °C. A thermal treatment permits complete chlorine removal forming sinterable crystalline LaCrO3 perovskite powder at temperatures above 720 °C. The same sol-gel process also can be applied to chlorine-free nitrate-containing alkoxide sols. The properties of sinterable lanthanum chromite powders obtained from these sols are compared with powders made by direct spray-drying of lanthanum-chromium nitrate solutions.

C−H Bond Activation by a Ferric Methoxide Complex: Modeling the Rate-Determining Step in the Mechanism of Lipoxygenase

Lipoxygenases are mononuclear non-heme iron enzymes that regio- and stereospecifcally convert 1,4-pentadiene subunit-containing fatty acids into alkyl peroxides. The rate-determining step is generally accepted to be hydrogen atom abstraction from the pentadiene subunit of the substrate by an active ferric hydroxide species to give a ferrous water species and an organic radical. Reported here are the synthesis and characterization of a ferric model complex, [Fe(III)(PY5)(OMe)](OTf)(2), that reacts with organic substrates in a manner similar to the proposed enzymatic mechanism. The ligand PY5 (2,6-bis(bis(2-pyridyl)methoxymethane)pyridine) was developed to simulate the histidine-dominated coordination sphere of mammalian lipoxygenases. The overall monoanionic coordination provided by the endogenous ligands of lipoxygenase confers a strong Lewis acidic character to the active ferric site with an accordingly positive reduction potential. Incorporation of ferrous iron into PY5 and subsequent oxidation yields a stable ferric methoxide species that structurally and chemically resembles the proposed enzymatic ferric hydroxide species. Reactivity with a number of hydrocarbons possessing weak C-H bonds, including a derivative of the enzymatic substrate linoleic acid, scales best with the substrates' bond dissociation energies, rather than pK(a)'s, suggesting a hydrogen atom abstraction mechanism. Thermodynamic analysis of [Fe(III)(PY5)(OMe)](OTf)(2) and the ferrous end-product [Fe(II)(PY5)(MeOH)](OTf)(2) estimates the strength of the O-H bond in the metal bound methanol in the latter to be 83.5 +/- 2.0 kcal mol(-1). The attenuation of this bond relative to free methanol is largely due to the high reduction potential of the ferric site, suggesting that the analogously high reduction potential of the ferric site in LO is what allows the enzyme to perform its unique oxidation chemistry. Comparison of [Fe(III)(PY5)(OMe)](OTf)(2) to other coordination complexes capable of hydrogen atom abstraction shows that, although a strong correlation exists between the thermodynamic driving force of reaction and the rate of reaction, other factors appear to further modulate the reactivity.

Transition Metal Complexes with Sterically Demanding Ligands, 3.1Synthetic Access to Square-Planar Terdentate Pyridine−Diimine Rhodium(I) and Iridium(I) Methyl Complexes: Successful Detour via Reactive Triflate and Methoxide Complexes

The synthesis of novel square-planar, terdentate, aryl-substituted pyridine−diimine Rh(I) and Ir(I) chloro complexes from the free ligands and the bis(μ-chloro) ethylene-bridged dimers [(C2H4)RhIrCl]2 is reported. Since attempts to achieve direct conversion to the corresponding hydride and methyl complexes through metathesis of the chloro ligand in these compounds were unsuccessful, synthetic access to more reactive methoxy- and triflate-substituted starting materials was developed. The methoxy and triflate complexes could be successfully converted to the Rh(I) η2-BH4 and Rh,Ir(I) methyl complexes. The structure and bonding and thermodynamics of the methoxy and η2-BH4 species were analyzed by DFT methods. X-ray crystal structures of selected Rh,Ir(I,III) representatives are reported.

Dicopper(II) complexes of a phenolate-hinged ditopic ligand with solvent-derived ancillary ligands bound at the potentially dimetallic exogenous site

Copper complexes based on the [Cu 2(bpbp)] 3+ core (bpbp −=2,6-bis(( N,N′-bis-(2-picolyl)amino)methyl)-4-tertbutylphenolate) containing methoxide or water ancillary ligands, [Cu 2(bpbp)(OCH 3)](ClO 4) 2 ( 1), [Cu 2(bpbp)(OH 2) 2](ClO 4) 3 ( 2) and Cu 2(bpbpH)(OH 2) 4(ClO 4) 4 ( 3), were isolated from methanol–water solutions above pH 3, between pH 2–3, and below pH 2, respectively. ESR and magnetochemistry reveal that the copper ions are antiferromagnetically ( J=−156 cm −1) and weakly ferromagnetically ( J=+5.3 cm −1) coupled in the doubly-bridged 1 and its singly-bridged pseudo acid congener 2, respectively. They are uncoupled in 3, consistent with each copper atom being bound only by an amine and two pyridine donors of bpbpH and oxygen donors of water and/or perchlorate. Thus the phenol residue of the dinucleating ligand is protonated and uncoordinated. Further, the ESR spectra show that complexes 1, 2 and 3 retain their integrity in solution. ESI mass spectra demonstrate that, as expected, the cations are labile in solution. However, the patterns that emerge support the formulations; numerous ions containing the [Cu 2(bpbp)] 3+ core plus water, hydroxide and methoxide ligands are observed. The intensities of the more protonated species increase in the spectra going from complex 1 to 3. The only complex to give a molecular ion for the intact cation was 1, and only from methanol solutions. However, the dominant ion observed in the mass spectra of 1 is [Cu 2(bpbp)(OH)] 2+ from all solvents tried. Thus in solution, the methoxide complex, 1, is in equilibrium with the isoelectronic hydroxide complex, [Cu 2(bpbp)(OH)](ClO 4) 2, with the latter favored. Complex 1 was used to provide a labile preformed core for bridge replacement reactions, and the acetate and pyrazolate complexes, [Cu 2(bpbp)(CH 3CO 2)](ClO 4) 2 ( 4) and [Cu 2(bpbp)(C 3H 3N 2)](ClO 4) 2 ( 5), were prepared in this manner.

Trichloro monophenoxide complexes of titanium(IV)

Thermalisation of TiCl4 and phenol (1∶1) in toluene gave [TiCl3(OC6H5)] 1. The more soluble complex [TiCl3(OC6H4CMe3-4)] 2 is monomeric in benzene and reacts with 4,4′-dimethyl-2,2′-bipyridyl (dmbipy) to give mer-[TiCl3(OC6H4CMe3-4)(dmbipy)] 3 and the disproportionation product [TiCl2(OC6H4CMe3-4)2(dmbipy)]. The complex [TiCl3(OC6H2Me3-2,4,6)] 4 is monomeric in benzene whereas [TiCl3(OC6H3Pri2-2,6)] 5 partially disproportionates in solution into [TiCl2(OC6H3Pri2-2,6)2] and reacts with dmbipy to give mer-[TiCl3(OC6H3Pri2-2,6)(dmbipy)] 6 and [TiCl2(OC6H3Pri2-2,6)2(dmbipy)]. Thermalisation of 2,6-di-tert-butyl-4-methylphenol and TiCl4 in toluene caused debutylation but [TiCl3{OC6H2(CMe3)2-2,6-Me-4}] 7 forms in light petroleum (bp range 40–60 °C). Complex 7 is monomeric in benzene and does not form adducts with dmbipy or other sigma donors. A crystal structure determination of 7 showed a monomer with distorted tetrahedral co-ordination, a Ti–O bond length of 1.750(2) A and Ti–Cl bonds longer than in TiCl4 but shorter than in [TiCl3(C5H5)] or [TiCl3{C5H3(CMe3)2-1,3}]. 2,4,6-Tri-tert-butylphenol debutylates when thermalised with TiCl4 in toluene giving [TiCl3{OC6H4(CMe3)2-2,4} ] 8. The complexes [TiCl3{OC6H2(CMe3)2-2,6-OMe-4}] 9, [TiCl3(OC6H3CMe3-2-Me-4)] 10, [TiCl3(OC6H4Ph-2)] 11 and the 1-naphthoxide complex [TiCl3(OC10H7)] 12 were also prepared. Density functional calculations performed on the models 4 and [TiCl3(OMe)] showed both lone pairs on oxygen donate electron density to titanium but O(2p)-to-CC (π*) donation weakens the Ti–O interaction in the phenoxide complex; Cl(2p)-to-Ti(3d) donation is much reduced in the methoxide complex. The system [TiCl3(OC6H4CMe3-4)]/AlMe3 is 280 times more active than [TiCl3Cp] (Cp = cyclopentadienyl)/AlMe3 for low pressure (6 psi) ethylene polymerisation but 1//3 less active than TiCl4/AlMe3.

EPR Spectroscopic Reinvestigation of the Activation of Iron Complexes of PMAH as a Bleomycin Model

The structure and reactivity of iron complexes of PMAH, which contains ligands that mimic the metal binding domain of iron bleomycin (FeBLM), have been studied using EPR spectroscopy. It had been reported [Guajardo, R. J.; Hudson, S. E.; Brown, S. J.; Mascharak, P. K. J. Am. Chem. Soc. 1993, 115, 7971] that iron complexes of PMAH can be activated to a ferric hydroperoxide, a structural analog by activated BLM, by various routes, including reaction of [FeIIIPMA]2+ with iodosylbenzene (PhIO), methanol, and base. We show that with or without PhIO, the latter reaction produces the methoxide complex of FeIIIPMA, and not the hydroperoxide, contrary to the previous report. Thus, O−O bond formation through generation of a ferric hydroperoxide does not occur. The same methoxide complex (g = 2.28, 2.18, 1.93) is generated by the addition of organic base and CH3OH, or LiOCH3, to [FeIIIPMA]2+. The formation of this [CH3O−FeIIIPMA]+ complex is confirmed by EPR titration of [FeIIIPMA]2+ with -OCH3 and by electrospray m...

Synthesis and single crystal X-ray structure of a novel trinuclear copper(II) methoxide complex

Reaction of the ligand cis, cis-1,3,5-tri-(E,E)- 3-(2-furyl)prop-2-en-1-ylidene-aminocyclohexane (tfct) with copper(II) ions and sodium tetrafluoroborate in methanol leads to the assembly of a novel trinuclear copper(II) complex. Single crystal X-ray diffraction shows that the complex contains a linear trinuclear array of copper(II) ions in which the central copper ion is coordinated by four methoxides, in a near square-planar coordination environment. The compound [Cu(tfct)2Cu(μ-OMe)4·2BF4 crystallises in the monoclinic system, space group P21/c, with a = 9.924(6), b = 14.620(13), c = 21.490(12)Å, β = 97.67(5)° and Z = 2. The [Cu(tfct) BF4)2+ units are related by a crystallographic inversion centre on the copper(II) ion of the central [Cu(μ-OMe)4]2 moiety.