Carbonato Ligand Research Articles

Syntheses, characterizations and crystal structures of two Ni(II) complexes [Ni2(neoc)4(H2O)(CO3)](NO3)2·3H2O and [Ni(bapa)2](NO3)2·H2O and magnetic properties of the carbonato complex

By the reaction of nickel(II) nitrate hexahydrate with 2,9-dimethyl-1,10-phenanthroline (neoc) and bis(3-aminopropyl)amine (bapa) two novel complexes were isolated, namely [Ni2(neoc)4(H2O)(CO3)](NO3)2·3H2O (1) and [Ni(bapa)2](NO3)2·H2O (2). Both structures are ionic and comprise hexacoordinated Ni(II) central atoms. Complex 1 is built up of dinuclear [Ni2(neoc)4(H2O)(CO3)]2+ complex cation, nitrate anions and water solvate molecules. The dinuclear complex cation is centrosymmetric and the two Ni(II) atoms are linked by a μ3-bridging-chelating carbonato ligand which, due to the presence of an inversion centre, exhibits two orientations with equal probability. The coordination sphere of Ni(II) atom is heteroleptic with an N4O2 donor set formed by two chelating neoc ligands and two O-donor atoms from bridging carbonato and aqua ligands. The carbonato ligand was formed by transformation of absorbed carbon dioxide from air (single crystals) or from dry ice (bulk sample). The crystal structure of 2 is formed by [Ni(bapa)2]2+ complex cation, nitrate anions and water solvate molecule. The coordination sphere of Ni(II) atom in 2 is homoleptic with N6 donor set. Both bapa ligands act as double chelating 3 N-donor ligands and are coordinated in mer-fashion. The study of the magnetic response of 1 in the temperature range 1.8–300 K revealed that the system can be considered as a system of antiferromagnetic S = 1 spin dimers with exchange interaction J/hc = -13.86 cm−1 (J/kB = -19.96 K) and axial single-ion anisotropy D/hc = -4.94 cm−1 (D/kB = -7.12 K). The experimental magnetic results were corroborated by ab initio and DFT calculations.

Facile Deoxygenative Reduction of a Bridging Carbonato Ligand with Silyl and Boryl 4,4’‐Bipyridinylidene Reagents

AbstractThe reactivity of CO2 with a previously described PCcarbeneP cobalt(I) hydroxide is reported. Insertion of CO2 into the Co−OH bond followed by a dehydration reaction releasing water results in a cobalt(I) bridging carbonate species featuring fluctional κ1: κ1 and κ1: κ2 coordination of the central carbonate moiety. The reduction chemistry of the resulting cobalt(I) bridging carbonate species is explored utilizing deoxygenative reducing agents N,N′‐bis(trimethylsilyl)‐ and N,N′‐bis(pinacolatoboryl)‐4,4′‐bipyridinylidene. The three‐electron reduction produces the corresponding PCcarbeneP cobalt(I) siloxide or boroxide complex alongside a PCcarbeneP cobalt(0) monocarbonyl, silyl/boryl ether, and 4,4’‐bipyridine.

Synthesis of Carbonato- and Doubly Oxido-Bridged Diruthenium(III,IV) Complex and Reactions with Cations.

Doubly oxido-bridged transition metal moieties, {M2(μ-O)2}, play important roles as oxidation reaction centers in nature. This work features a diruthenium(III,IV) complex with a doubly oxido-bridged core {Ru2III,IV(μ-O)2}3+ with a carbonato bridged between the two ruthenium centers, M[{RuIII,IV(ebpma)}2(μ-O)2(μ-O2CO)]2(PF6)3 (M[1CO3]2(PF6)3; Carbonato complex, ebpma; ethylbis(2-pyridymethyl)amine), and explores the interactions of this complex with cations (H+ and M+). M[1CO3]2(PF6)3 was formed via reactions of a singly oxido-bridged complex, [{RuIII,IVCl2(ebpma)}2(μ-O)]PF6·(CH3)2CO, with M2CO3 (M = K, Na) or with CO2(g), adjusted to around pH 12 with NaOH(aq.), in a water-acetone mixed solvent. The Carbonato complex was isolated as a powder in the form of M[1CO3]2(PF6)3 (M = K, Na), because of the interactions between the carbonato moiety and K+ or Na+ in the solid structure. In acidic aqueous solutions, unexpectedly, the carbonato ligand remained bound to the doubly bridged core, {Ru2III,IV(μ-O)2}3+ or {Ru2III,IV(μ-O)(μ-OH)}4+, without decarboxylation even under pH 1.0. Two-step one-protonation/deprotonation occurred reversibly between pH 1.0 and 13.2 to the bridging oxido and carbonato ligands. The structures of the corresponding one- and two-protonated complexes ([1CO3H]2+ and [1CO32H]3+) were successfully characterized.

Interactions of Molecular Titanium Oxides TiO x ( x = 1-3) with Carbon Dioxide in Cluster Anions.

We study small titanium oxide-CO2 cluster anions in vacuo to understand the fundamental interactions between TiO x and CO2 in the presence of an excess electron. Infrared spectra of [TiO x(CO2) y]- ( x = 1-3, y > 1) were obtained using photodissociation spectroscopy and assigned through quantum chemistry calculations, identifying the formation of carbonato, oxalato, oxo, η2-(O,O), and carbonyl ligands in the core ions of these clusters, with carbonato ligands being the dominant ligand species.

Exploring the Role of Carbonate in the Formation of an Organomanganese Tetramer

The formation of metal-oxygen clusters is an important chemical transformation in biology and catalysis. For example, the biosynthesis of the oxygen-evolving complex in the enzyme photosystem II is a complicated stepwise process that assembles a catalytically active cluster. Herein we describe the role that carbonato ligands have in the formation of the known tetrameric complex [Mn(CO)3(μ3-OH)]4 (1). Complex 1 is synthesized in one step via the treatment of Mn2(CO)10 with excess Me3NO·2H2O. Alternatively, when anhydrous Me3NO is used, an OH-free synthetic intermediate (2) with carbonato ligands is produced. Complex 2 produces carbon dioxide, Me3NO·2H2O, and 1 when treated with water. Labeling studies reveal that the μ3-OH ligands in 1 are derived from the water and possibly the carbonato ligands in 2.

Reactivity of the Donor-Stabilized Silylenes [iPrNC(Ph)NiPr]2 Si and [iPrNC(NiPr2 )NiPr]2 Si: Activation of CO2 and CS2.

Activation of CO2 by the bis(amidinato)silylene 1 and the analogous bis(guanidinato)silylene 2 leads to the structurally analogous six-coordinate silicon(IV) complexes 4 (previous work) and 8, respectively, the first silicon compounds with a chelating carbonato ligand. Likewise, CS2 activation by silylene 1 affords the analogous six-coordinate silicon(IV) complex 10, the first silicon compound with a chelating trithiocarbonato ligand. CS2 activation by silylene 2, however, yields the five-coordinate silicon(IV) complex 13 with a carbon-bound CS2 (2-) ligand, which also represents an unprecedented coordination mode in silicon coordination chemistry. Treatment of the dinuclear silicon(IV) complexes 5 and 6 with CO2 also affords the six-coordinate carbonatosilicon(IV) complexes 4 and 8, respectively.

Tetraammine(carbonato-κ2O,O′)cobalt(III) perchlorate

In the title complex, [Co(CO3)(NH3)4]ClO4, both the cation and anion lie on a mirror plane. The CoIII ion is coordinated by two NH3 ligands and a chelating carbonato ligand in the equatorial sites and by two NH3 groups in the axial sites, forming a distorted octa­hedral geometry. In the crystal, N—H⋯O hydrogen bonds connect the anions and cations, forming a three-dimensional network.

Synthesis, structure and reactivity of NHC–nickel complexes containing carbonato ligands

Reactions of different alkane-bridged (n = 1–3) di-NHC precursors, bisimidazolium chlorides with the NiCl2 in presents of K2CO3 in acetonitrile give the corresponding 16-electron binuclear complexes of the type Ni(di-NHC)(μ-O)2CO in moderate yield. The molecular structures of 1–3 have been determined by X-ray crystallography, which revealed a cis-chelating di-NHC on a slightly distorted square-planar nickel center with κ2-cabonato ligand. The influence of the different di-NHC ligands on the structure and reactivity of the complexes has been studied. The catalytic properties of the complexes were investigated in the Kumada reaction for cross-coupling of phenylmagnesium bromide with a variety of aryl halides. The complex 3 which has the longest linker between two NHCs shows the best catalytic activity in these reactions.

Molecular Assembly and Magnetic Dynamics of Two Novel Dy6and Dy8Aggregates

Complexation of dysprosium(III) with the heterodonor chelating ligand o-vanillin picolinoylhydrazone (H(2)ovph) in the presence of a carbonato ligand affords two novel Dy(6) and Dy(8) clusters, namely, [Dy(6)(ovph)(4)(Hpvph)(2)Cl(4)(H(2)O)(2)(CO(3))(2)]·CH(3)OH·H(2)O·CH(3)CN (2) and [Dy(8)(ovph)(8)(CO(3))(4)(H(2)O)(8)]·12CH(3)CN·6H(2)O (3). Compound 2 is composed of three petals of the Dy(2) units linked by two carbonato ligands, forming a triangular prism arrangement, while compound 3 possesses an octanuclear core with an unprecedented tub conformation, in which Dy(ovph) fragments are attached to the sides of the carbonato core. The static and dynamic magnetic properties are reported and discussed. In the Dy(6) aggregate, three Dy(2) "skeletons", having been well preserved (see the scheme), contribute to the single-molecule-magnet behavior with a relatively slow tunneling rate, while the Dy(8) cluster only exhibits a rather small relaxation barrier.

One-pot synthesis of cis-bis(2,2′-bipyridine)carbonylruthenium(II) complexes from a carbonato precursor: X-ray crystal structures and electron transfer processes of the series complexes

The reaction of Brønsted acids with cis-[Ru(bpy)2(CO3)] (bpy = 2,2′-bipyridine) under CO results in cleavage of the carbonato ligand and formation of cationic cis-[Ru(bpy)2(CO)L] n + complexes [L = ONO2 (1 +), OH2 (2 2+), Cl (3 +), OCOH (4 +), and OCOCH3 (5 +)]. The structures of 1 + and 2 2+ were confirmed by single-crystal X-ray diffraction. Crystal data for 1(PF6): monoclinic, P21/c, a = 10.5242(3), b = 15.4727(3), c = 14.6571(3) Å, β = 92.3219(9)°, V = 2384.77(9) Å3, Z = 4, D calcd = 1.806 g cm−3, 5460 unique reflections (R int = 0.032), R 1 = 0.0540 [I > 2σ(I)], wR 2 = 0.1642 (all reflections); crystal data for 2(ClO4)2 · H2O: monoclinic, C2/c, a = 20.4247(7), b = 10.0777(3), c = 15.6039(5) Å, β = 127.7569(8)°, V = 2539.31(14) Å3, Z = 4, D calcd = 1.769 g cm−3, 2895 unique reflections (R int = 0.036), R 1 = 0.0343 [I > 2σ(I)], wR 2 = 0.0907 (all reflections). Except for 2(PF6)2 the complexes exhibit oxidation at 1.02–1.30 V versus Fc+/Fc in acetonitrile. Bipyridine-centered reductions are also observed; these redox potentials depend on the nature of L. This convenient synthesis will be useful for producing cis-[Ru(bpy)2(CO)L] n +-type complexes in high yield.

Cationic cobalt(III) complex as anion receptor: Synthesis, spectroscopic characterization, single-crystal X-ray structure determination and packing analyses of [Co(phen) 2CO 3](4-aminobenzenesulphonate).6H 2O

To explore the potential of [Co(phen) 2CO 3] + as anion receptor, the complex salt [Co(phen) 2CO 3](4-aminobenzenesulphonate).6H 2O was synthesized and characterized by X-ray crystallography, elemental analyses, spectroscopic studies (IR, UV/Visible, 1H, 13C and 59Co NMR), solubility product and conductance measurements. The complex salt crystallizes in the triclinic space group P 1 ¯ with unit cell constants: a = 10.803(2), b = 11.758(2), c = 15.190(3) Å, α = 99.66(3)°, β = 103.53(3)°, γ = 113.54(3)°. X-ray structure determination revealed the presence of one [Co(phen) 2CO 3] +, one 4-aminobenzenesulphonate ion and six lattice water molecules per asymmetric unit. Two 1,10-phenanthroline and one carbonato ligands (each bidentate) showed distorted octahedral geometry around the central Co(III) metal ion. Supramolecular hydrogen bonding networks formed by C–H···O, O–H···O and N–H···O interactions besides electrostatic forces of attraction stabilize crystal lattice. The structural studies suggest that [Co(phen) 2CO 3] + is a potential anion receptor for the 4-aminobenzenesulphonate ion in aqueous medium.

Octa- and Nonanuclear Nickel(II) Polyoxometalate Clusters: Synthesis and Electrochemical and Magnetic Characterizations

Three high-nuclearity NiII-substituted polyoxometalate compounds functionalized by exogenous ligands have been synthesized and characterized. The octanuclear complexes in Na15[Na{(A-R-SiW9O34)Ni4(CH3COO)3(OH)3}2] . 4NaCl . 36H2O (1) and Na15[Na{(A-R-SiW9O34)Ni4(CH3COO)3(OH)2(N3)}2] . 32H2O (2) can be described as two {Ni4} subunits connected via a {Na(CH3COO)6} group, with the acetato ligands also ensuring in each subunit the connection between the paramagnetic centers. In 2, two azido groups replace two of the six mu-hydroxo ligands present in 1. The nonanuclear complex K7Na7[(A-R-SiW9O34)2Ni9(OH)6(H2O)6(CO3)3] . 42H2O (3) exhibits a double cubanestructure with two [(A-R-SiW9O34)Ni4(OH)3]5- subunits linked by three carbonato ligands. A ninth NiII center connected to one subunit via a carbonato ligand and a O=W group completes this asymmetric polyoxometalate.Electronic spectroscopy and electrochemical studies indicate that, while compounds 1-3 decompose in a pure aqueous medium, these complexes are very stable in a pH 6 acetate medium. The cyclic voltammetry pattern of each complex is constituted by a first eight-electron reduction wave followed by a second large-current intensity wave. The characteristics of the first waves of the complexes are clearly distinct from those obtained for their lacunary precursor [A-R-SiW9O34]10-, a feature that is due to the Ni centers in the complexes. Such observations of electroactive, stable, and highly nickel-rich polyoxometalates are not common. Measurements of the magnetic susceptibility revealed the occurrence of concomitant ferromagnetic and antiferromagnetic interactions in 1 and 3.For both of these compounds, the extension of the magnetic exchange has been determined by means of a spin Hamiltonian with three and four J constants, respectively.

Kinetics and Mechanism of Formation and Acid–Catalyzed Decomposition of the [Co(NH3)4CO3]+ Complex Cation in Aqueous Solution

AbstractIt has been found that the kinetics of acid‐catalyzed hydrolysis of the [Co(NH3)4CO3]+ cation follows the rate law –d ln [complex]/d t = k1K[H+]/(1+K[H+]) (5 °C < T < 25 °C; 0.0543M < [HClO4] < 2.7M and I = 1.0M (NaClO4). The reaction course consists of a rapid pre‐equlibrium protonation followed by a rate determining ring opening process and the subsequent fast release of monodentate carbonato ligand. The changes of the absorbance for the acidic aqueous solution of the [Co(NH3)4CO3]+ complex ion proceeded at relevant wavelength in the UV‐Vis region and time course of these changes were analysed according to a programme “Glint” for the consecutive first – order reaction with two experimental rate constants kfast and kslow. Finally, the aquation mechanism has been proposed and the effect of ligand coordination mode (bidentate carbonato anion) on complex reactivity has been discussed.

Effect of Cyanato, Azido, Carboxylato, and Carbonato Ligands on the Formation of Cobalt(II) Polyoxometalates: Characterization, Magnetic, and Electrochemical Studies of Multinuclear Cobalt Clusters.

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Effect of Cyanato, Azido, Carboxylato, and Carbonato Ligands on the Formation of Cobalt(II) Polyoxometalates: Characterization, Magnetic, and Electrochemical Studies of Multinuclear Cobalt Clusters

Five Co(II) silicotungstate complexes are reported. The centrosymmetric heptanuclear compound K(20)[{(B-beta-SiW(9)O(33)(OH))(beta-SiW(8)O(29)(OH)(2))Co(3)(H(2)O)}(2)Co(H(2)O)(2)]47 H(2)O (1) consists of two {(B-beta-SiW(9)O(33)(OH))(beta-SiW(8)O(29)(OH)(2))Co(3)(H(2)O)} units connected by a {CoO(4)(H(2)O)(2)} group. In the chiral species K(7)[Co(1.5)(H(2)O)(7))][(gamma-SiW(10)O(36))(beta-SiW(8)O(30)(OH))Co(4)(OH)(H(2)O)(7)]36 H(2)O (2), a {gamma-SiW(10)O(36)} and a {beta-SiW(8)O(30)(OH)} unit enclose a mononuclear {CoO(4)(H(2)O)(2)} group and a {Co(3)O(7)(OH)(H(2)O)(5)} fragment. The two trinuclear Co(II) clusters present in 1 enclose a mu(4)-O atom, while in 2 a mu(3)-OH bridging group connects the three paramagnetic centers of the trinuclear unit, inducing significantly larger Co-L-Co (L=mu(4)-O (1), mu(3)-OH (2)) bridging angles in 2 (theta(av(Co-L-Co))=99.1 degrees ) than in 1 (theta(av(Co-L-Co))=92.8 degrees ). Weaker ferromagnetic interactions were found in 2 than in 1, in agreement with larger Co-L-Co angles in 2. The electrochemistry of 1 was studied in detail. The two chemically reversible redox couples observed in the positive potential domain were attributed to the redox processes of Co(II) centers, and indicated that two types of Co(II) centers in the structure were oxidized in separate waves. Redox activity of the seventh Co(II) center was not detected. Preliminary experiments indicated that 1 catalyzes the reduction of nitrite and NO. Remarkably, a reversible interaction exists with NO or related species. The hybrid tetranuclear complexes K(5)Na(3)[(A-alpha-SiW(9)O(34))Co(4)(OH)(3)(CH(3)COO)(3)]18 H(2)O (3) and K(5)Na(3)[(A-alpha-SiW(9)O(34))Co(4)(OH)(N(3))(2)(CH(3)COO)(3)]18 H(2)O (4) were characterized: in both, a tetrahedral {Co(4)(L(1))(L(2))(2)(CH(3)COO)(3)} (3: L(1)=L(2)=OH; 4: L(1)=OH, L(2)=N(3)) unit capped the [A-alpha-SiW(9)O(34)](10-) trivacant polyanion. The octanuclear complex K(8)Na(8)[(A-alpha-SiW(9)O(34))(2)Co(8)(OH)(6)(H(2)O)(2)(CO(3))(3)]52 H(2)O (5), containing two {Co(4)O(9)(OH)(3)(H(2)O)} units, was also obtained. Compounds 2, 3, 4, and 5 were less stable than 1, but their partial electrochemical characterization was possible; the electronic effect expected for 3 and 4 was observed.

Direct Preparation of [Ru(η2‐O2CO)(η6‐arene)(L)] Carbonate Complexes (L = Phosphane, Carbene) and Their Use as Precursors of [RuH2(p‐cymene)(PCy3)] and [Ru(η6‐arene)(L)(MeCN)2][BF4]2: X‐ray Crystal Structure Determination of [Ru(η2‐O2CO)(p‐cymene)(PCy3)]·1/2CH2Cl2 and [Ru(η2‐O2CO)(η6‐C6Me6)(PMe3)]·H2O

Abstract[RuCl2(η6‐arene)(PR3)] complexes react with K2CO3 in the presence of water to afford the carbonatoruthenium(II) derivatives [Ru(η2‐O2CO)(η6‐arene)(PR3)] (2; arene = p‐cymene, R = Cy, Ph, or Me; arene = hexamethylbenzene, R = Me) involving a planar Ru(η2‐O2CO) moiety as shown by X‐ray crystal structure determination of 2a (p‐cymene, PCy3) and 2d (hexamethylbenzene, PMe3). The complex [Ru(η2‐O2CO)(p‐cymene)(PCy3)] is cleanly converted in hot methanol into the dihydride [RuH2(p‐cymene)(PCy3)]. The related complexes [Ru(η2‐O2CO)(η6‐arene)(IMes)] [arene = p‐cymene or hexamethylbenzene, IMes = 1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene] are straightforwardly prepared by treating [RuCl2(η6‐arene)]2 precursors with 1,3‐bis(2,4,6‐trimethylphenyl)imidazolium chloride and K2CO3 in THF at reflux. The removal of the carbonato ligand from complexes 2 with HBF4 in the presence of acetonitrile leads to the dicationic derivatives [Ru(η6‐arene)(L)(MeCN)2][BF4]2 (L = PR3 or IMes). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Carbon Dioxide Activation Assisted by a Bis(chlorodimethylsilyl)cyclopentadienyl Titanium Compound

A helping hand: The assisted fixation of CO2 and its transformation into a carbonato ligand has been achieved using a di(silyl)cyclopentadienyl titanium(IV) complex. In the presence of water and under air, a dinuclear carbonato titanium(III) complex (see picture) is formed. Theoretical investigations into the electronic properties of this titanium(III) complex explain its high stability and diamagnetism.

First example of atmospheric carbon dioxide uptake by a cyanocomplex: Preparation and structural characterization of Zn 2( tn) 2(CO 3)Ni(CN) 4 · H 2O ( tn = 1,3-diaminopropane)

The aqueous system Zn(II)- tn-[Ni(CN) 4] 2− in contact with air captured carbon dioxide in the form of a carbonato ligand yielded the compound Zn 2( tn) 2(CO 3)Ni(CN) 4 · H 2O by crystallization, which was characterized by elemental analyses, IR spectroscopy and single crystal structure analysis. Its crystal structure is polymeric and is built up of a positively charged framework [ Zn 4 ( tn ) 4 ( CO 3 ) 2 Ni ( CN ) 4 ] n 2 n + , free tetracyanonickellate anions with a nickel atom on the inversion centre and water molecules of crystallization. Two crystallographically different zinc atoms exhibit tetrahedral and penta-coordinations. The zinc atoms are interconnected by two crystallographically independent bridging tn ligands, μ 3 - CO 3 2 - carbonato ligand and one centrosymmetric tetracyanonickellate anion acting as trans-[-NC-Ni(CN) 2-CN-] ligand. The carbonato ligand coordinates three zinc atoms by an unusual mode, two by an unidentate and one by a bidentate fashion with one oxygen donor atom forming two Zn–O coordination bonds.

Molecular dynamics simulation of uranyl(vi) adsorption equilibria onto an external montmorillonite surface

We used molecular dynamics simulations to study the adsorption of aqueous uranyl species (UO(2)(2+)) onto clay mineral surfaces in the presence of sodium counterions and carbonato ligands. The large system size (10,000 atoms) and long simulation times (10 ns) allowed us to investigate the thermodynamics of ion adsorption, and the atomistic detail provided clues for the observed adsorption behavior. The model system consisted of the basal surface of a low-charge Na-montmorillonite clay in contact with aqueous uranyl carbonate solutions with concentrations of 0.027 M, 0.081 M, and 0.162 M. Periodic boundary conditions were used in the simulations to better represent an aqueous solution interacting with an external clay surface. Uranyl adsorption tendency was found to decrease as the aqueous uranyl carbonate concentration was increased, while sodium adsorption remained constant. The observed behavior is explained by physical and chemical effects. As the ionic strength of the aqueous solution was increased, electrostatic factors prevented further uranyl adsorption once the surface charge had been neutralized. Additionally, the formation of aqueous uranyl carbonate complexes, including uranyl carbonato oligomers, contributed to the decreased uranyl adsorption tendency.

ひずみをもった金属錯体の量子化学計算‐炭酸イオンがキレート配位した八面体型コバルト(III)錯体の構造最適化‐

ひずみをもった金属錯体の量子化学計算‐炭酸イオンがキレート配位した八面体型コバルト(III)錯体の構造最適化‐