Reversible One-electron Redox Waves Research Articles

A new organometallic rhodium(I) complex with dpp-bian ligand: Synthesis, structure and redox behaviour

Reaction of [{Rh(COD)}2(μ-Cl)2] with 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) has afforded a new organometallic complex [Rh(COD)(dpp-bian)Cl] (1). The crystal structure of 1·0.25H2O was determined by X-ray single crystal analysis. The rhodium(I) ion has a distorted square-pyramidal coordination. The RhCl distance (2.5908 (12) Å) is rather long, indicating weak coordination of the chloride. Dissociation of chloride in solution to produce cationic [Rh(COD)(bian)]+ ([1-Cl]+) was confirmed by ESI-MS, 1H NMR, CV and DFT calculations. Cyclic voltammetry of 1 in acetonitrile (CH3CN) showed two reversible one-electron redox waves at E1/2 = −0.36 V and −1.18 V (versus Ag/AgCl) attributable to successive reduction of the dpp-bian ligand in [1-Cl]+. DFT calculations were performed to explain the anomalously long RhCl distance and interpret the reduction sequence of 1.

Transformation of a μ3-Benzyne Ligand into Phenol on a Cationic Triruthenium Cluster Supported by a μ3-Sulfido Ligand

A triruthenium complex containing μ3-η2(||)-benzyne and μ3-sulfido ligands, [(Cp*Ru)3(μ3-S){μ3-η2(||)-C6H4}(μ-H)] (2), was synthesized by the reaction of [(Cp*Ru)3(μ3-S)(μ-H)3] (1) with benzene. Although 2 was stable toward oxygen and water, two-electron oxidation of 2 with a Ag(I) salt in the presence of water afforded the dicationic μ-hydroxo complex [(Cp*Ru)3(μ3-S){μ3-η2(||)-C6H4}(μ-OH)]2+ (3). Treatment of 3 with amine resulted in the deprotonation of the μ-hydroxo ligand, and an unsaturated monocationic complex, [(Cp*Ru)3(μ3-S)(μ3-OC6H4-κO,κC)]+ (4), which possesses a μ3-cyclohexadienonediyl ligand, was formed via reductive C–O bond formation between the μ3-benzyne and transient μ-oxo ligands. Phenol was extruded from the Ru3 cluster upon the hydrogenation of 4 via the formation of a μ3-phenoxo complex, [(Cp*Ru)3(μ3-S){μ3-OPh}(μ-H)]+ (5). The cyclic voltammogram of 2 shows two reversible one-electron redox waves, and a dicationic μ3-benzyne complex, [(Cp*Ru)3(μ3-S){μ3-η2:η2(⊥)-C6H4}(μ-H)]2+(8), was s...

Electron-rich bioctahedral rhenium chalcohalide clusters [Re12CS14(µ-S)3Cl6]8− and [Re12CS14(µ-S)3Br6]8−: Synthesis, structure and properties

A first method for obtaining of electron-rich bioctahedral rhenium clusters has been developed. Two cluster salts, namely (Et3NH)4(Me2NH2)4[Re12CS14(µ-S)3Cl6] (1) and (Et4N)4(Me2NH2)4[Re12CS14(µ-S)3Br6] (2), have been synthesized and isolated in the solid state. Single-crystal X-ray diffraction showed that salts 1 and 2 are based on the new cluster anions [Re12CS14(µ-S)3Cl6]8− and [Re12CS14(µ-S)3Br6]8− containing 48 cluster valence electrons (CVE). The correlations between geometry and CVE number of the bioctahedral chalcohalide anions have been examined using the DFT calculations. The dissolution of the salts 1 and 2 is accompanied by the oxidation yielding the [Re12CS14(µ-S)3Cl6]6− and [Re12CS14(µ-S)3Br6]6− anions. Properties of the new clusters in the DMSO solutions have been investigated by UV–Vis spectroscopy and cyclic voltammetry. The latter revealed the presence of multiple reversible one-electron redox waves in a narrow potential window.

Influence of Axial Ligands on Diverse Properties in Three Trinickel String Complexes

Three new trinickel string complexes, [Ni3(dpa)4(3-nba)2](1), [Ni3(dpa)4(4-nba)2]·(CH3OH) (2), and [Ni3(dpa)4(3,5-dnba)2](3) where dpa− is the anion of 2,2′-dipyridylamine, 3-nba− is 3-nitrobenzoate anion, 4-nba− is 4-nitrobenzoate anion, and 3,5-dnba− is 3,5-dinitrobenzoate anion, were synthesized in good yield and characterized by X-ray crystallography, infrared spectra, elemental analysis, magnetic susceptibility, cyclic voltammogram (CV), UV-vis spectra, fluorescence spectra, and TG analysis. The magnetic susceptibilities suggested that the terminal Ni atoms in all three complexes are in high-spin state while the central Ni atom is in a low-spin state. The CVs of complexes 1–3 showed reversible one-electron redox waves at E1/2 = 1.1395 V for 1, 1.108 V for 2, and 1.109 V for 3 corresponding to Ni3 7+/Ni3 6+. The Ni-Ni distances in three complexes are somewhat different, indicating the axial nitrobenzoate ligands have significant effect on the structural assembly. Supplemental materials are available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.

Hydrazine oxidation catalyzed by ruthenium hexacyanoferrate-modified glassy carbon electrode

A ruthenium (III) hexacyanoferrate (Ru(HCF)) film coated on a glassy carbon electrode was explored as an electrocatalyst for hydrazine oxidation. Surface cyclic voltammograms of Ru(HCF) film showed four reversible one-electron redox waves. Two, which corresponded to the redox processes of Ru(III)/Ru(IV) and Fe(II)/Fe(III), were identified to be responsible for the catalytic activity of hydrazine oxidation. Kinetic studies using potential scan rate dependency, Tafel plots, and rotating disk electrode technique found that this catalyzed hydrazine oxidation was a complete four-electron/four-proton process producing N2, with the rate determining step possibly a one-electron process with a transfer coefficient (α) of ~0.31–0.36. In addition, based on kinetic analysis and findings in the literature, we propose a possible reaction mechanism for catalyzed hydrazine oxidation in order to facilitate further understanding.

Synthesis and Characterization of Ir(H)(CO)(PEt3})2(η2-C60)

The title complex, Ir(H)(CO)(PEt3)2(η 2 -C 60 ) (2), has been prepared by the reaction of excess C 60 (4 equiv) with a tetrairidium complex Ir 4 (CO) 8 (PEt 3 ) 4 (1) in refluxing chlorobenzene in 40% yield as green crystals. Compound 2 has been characterized by cyclic voltammetry (CV), spectroscopic methods (mass, IR, 1 H and 31 P NMR), and a single crystal X-ray diffraction study. The molecular structure reveals that the iridium atom of 2 is coordinated by two axial ligands of a hydrogen atom and a carbonyl group, and three equatorial ligands of two phosphorus atoms and an η 2 -C 60 moiety. The CV study exhibits three reversible one-electron redox waves for the successive reductions of 2, together with additional four redox waves due to free C 60 reductions, which was formed by decomposition of 2 in the reduced states. The three reversible redox waves of 2 are shifted to more negative potentials by ca. 270 mV compared to free C 60 , reflecting both metal-to-C 60 π-back-donation and the electron-donating nature of the two phosphorus ligands.

Synthesis, spectroscopic, structural and electrochemical studies of carboxyl substituted 1,4-naphthoquinones

Two carboxyl substituted quinones and their ethyl esters were prepared by alkylation of 2-methyl-1,4-naphthoquinone (MNQ), also known as menadione or vitamin K3. All products were characterized by spectroscopic (1H NMR, 13C NMR, IR) and electrochemical (cyclic voltammetry) methods, and the crystal structure of the two carboxylic derivatives was also determined. Both carboxyl substituted quinones crystallize in the P1¯ system as hydrogen bonded dimers. In MeCN, the cyclic voltammograms of the ester derivatives present two reversible one-electron redox waves very similar to those of the parent quinone, MNQ. However, in the same solvent, the corresponding carboxyl substituted quinones show one cathodic and one anodic additional irreversible waves at more positive potentials and a decrease in current intensity of the two quinone reduction waves accompanied by loss of the quasi-reversible character of the second wave. These results show that the presence of the carboxylic substituent does not greatly modify the redox behaviour of the quinone, except for a small anodic shift of the potentials, but the associated presence of H+ ions in solution causes an important perturbation to the system, stabilizing the electrogenerated semiquinones by intermolecular self-protonation and/or hydrogen bonding.

Strong interfullerene electronic communication in a bisfullerene-hexarhodium sandwich complex.

Reaction of Rh(6)(CO)(12)(dppm)(2) (dppm = 1,2-bis(diphenylphosphino)methane) with 1.4 equiv. of C(60) in chlorobenzene at 120 degrees C affords a face-capping C(60) derivative Rh(6)(CO)(9)(dppm)(2)(micro(3)-eta(2),eta(2),eta(2)-C(60)) (1) in 73% yield. Treatment of 1 with excess CNR (10 equiv., R = CH(2)C(6)H(5)) at 80 degrees C provides a bisbenzylisocyanide-substituted compound Rh(6)(CO)(7)(dppm)(2)(CNR)(2)(micro(3)-eta(2),eta(2),eta(2)-C(60)) (2) in 59% yield. Reaction of 1 with excess C(60) (4 equiv.) in refluxing chlorobenzene followed by treatment with 1 equiv. of CNR at room temperature gives a bisfullerene sandwich complex Rh(6)(CO)(5)(dppm)(2)(CNR)(micro(3)-eta(2),eta(2),eta(2)-C(60))(2) (3) in 31% yield. Compounds 1, 2, and 3 have been characterized by spectroscopic and microanalytical methods as well as by X-ray crystallographic studies. Electrochemical properties of 1, 2, and 3 have been examined by cyclic voltammetry. The cyclic voltammograms (CVs) of 1 and 2 show two reversible one-electron redox waves, a reversible one-step two-electron redox wave, and a reversible one-electron redox wave, respectively, within the solvent cutoff window. This observation suggests that compounds 1 and 2 undergo similar C(60)-localized electrochemical pathways up to 1(5)(-) and 2(5)(-). Each redox wave of 2 appears at more negative potentials compared to that of 1 because of the donor effect of the benzylisocyanide ligand. The CV of compound 3 reveals six reversible well-separated redox waves due to strong interfullerene electronic communication via the Rh(6) metal cluster bridge. The electrochemical properties of 1, 2, and 3 have been rationalized by molecular orbital calculations using the density functional theory (DFT) method. In particular, the molecular orbital (MO) calculation reveals significant contribution of the metal cluster center to the unoccupied molecular orbitals in 3, which is consistent with the experimental result of strong interfullerene electronic communication via the Rh(6) metal cluster spacer.

Reaction of Mixed-Ligand Iron–Sulfur Cluster [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2)] (Cp* = C5Me5) with Methyl Iodide. Synthesis, Structure, and Redox Behavior of [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2Me)

Abstract The reaction of the mixed-ligand iron–sulfur cluster [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2)] ([3]) (Cp* = C5Me5) with iodomethane gave a methylated cluster, [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2Me)]I ([4]I), in 60% yield. The anion exchange of [4]I with KPF6 gave [4]PF6 as a pure sample. A similar treatment of [3] using iodoethane afforded an ethylated cluster, [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2Et)]I ([5]I), and oxidized parent cluster [3]I. The reaction of [3] with 2-iodopropane did not give an alkylated cluster. An unreacted cluster [3] was recovered with a small amount of oxidized cluster [3]I. The molecular structure of [Fe4(Cp*)3(Ph2C2S2)(μ3-S)3(μ3-S2Me)] ([4]), which was obtained by the reduction of [4]PF6 with cobaltocene, was determined by an X-ray diffraction study. Crystallographic data are: Monoclinic, P21/a, a = 21.707(2) Å, b = 21.382(2) Å, c = 11.433(1) Å, β = 98.98(1)°, V = 5241.5(9) Å3, Z = 4, and R = 0.067 for 7412 reflections with |Fo| > 3σ(Fo). The methyl group transferred from MeI is located on the singly ligating sulfur atom in the disulfide ligand of the parent cluster [3]. A cyclic voltammogram of [4]PF6 in 0.1 mol dm−3 tetrabutylammonium tetrafluoroborate–CH3CN showed five reversible one-electron redox waves at E1/2 = +1.42 V, +0.92 V, +0.41 V, −0.38 V, and −1.22 V vs SCE, corresponding to 4+/3+, 3+/2+, 2+/1+, 1+/0, and 0/1− charged cluster couples, respectively. An irreversible two-electron reduction wave was also observed at Epc = −1.97 V vs SCE.

Electroactive Self-Assembled Biferrocenyl Alkanethiol Monolayers on Au(111) Surface and on Gold Nanoclusters

The spectroscopic and electrochemical characterizations of electrochemically stable biferrocene-modified Au clusters and chemisorbed biferrocenylalkanethiols on Au(111) surface were studied. The characterizations of biferrocene-modified Au cluster using TEM, UV-vis, and NMR techniques are also reported. Two successive reversible one-electron redox waves were observed for the biferrocenylalkanethiol Au nanoclusters and biferrocenylalkanethiol monolayers on Au(111) surface in the cyclic voltammetry. Furthermore, the positive and negative current peaks for each redox wave occur at almost the same potential, and the peak current increases almost linearly with the sweep rate. Repeat scanning does not change the voltammograms, demonstrating that these monolayers are stable to electrochemical cycling. The coverages of electroactive biferrocene in the monolayers were calculated from the cyclic voltammograms. The standard electron-transfer rate constant was calculated from the splitting between the oxidation and reduction peaks.

Synthesis and electrochemical studies of diiron complexes of 1,8-naphthyridine-based dinucleating ligands to model features of the active sites of non-heme diiron enzymes.

A bis(mu-carboxylato)(mu-1,8-naphthyridine)diiron(II) complex, [Fe2(BPMAN)(mu-O2CPhCy)2](OTf)2 (1), was prepared by using the 1,8-naphthyridine-based dinucleating ligand BPMAN, where BPMAN = 2,7-bis[bis(2-pyridylmethyl)aminomethyl]-1,8-naphthyridine. The cyclic voltammogram (CV) of this complex in CH2Cl2 exhibited two reversible one-electron redox waves at +296 mV (DeltaE(p) = 80 mV) and +781 mV (DeltaE(p) = 74 mV) vs Cp2Fe+/Cp2Fe, corresponding to the FeIIIFeII/FeIIFeII and FeIIIFeIII/FeIIIFeII couples, respectively. This result is unprecedented for diiron complexes having no single atom bridge. Dinuclear complexes [Fe2(BPMAN)(mu-OH)(mu-O2CPhCy)](OTf)2 (2) and [Mn2(BPMAN)(mu-O2CPhCy)2](OTf)2 (3) were also synthesized and structurally characterized. The cyclic voltammogram of 2 in CH2Cl2 exhibited one reversible redox wave at -22 mV only when the potential was kept below +400 mV. The CV of 3 showed irreversible oxidation at potentials above +900 mV. Diiron(II) complexes [Fe2(BEAN)(mu-O2CPhCy)3](OTf) (4) and [Fe2(BBBAN)(mu-OAc)2(OTf)](OTf) (6) were also prepared and characterized, where BEAN = 2,7-bis(N,N-diethylaminomethyl)-1,8-naphthyridine and BBBAN = 2,7-bis[2-[2-(1-methyl)benzimidazolylethyl]-N-benzylaminomethyl]-1,8-naphthyridine. The cyclic voltammograms of these complexes were recorded. The Mössbauer properties of the diiron compounds were studied.

Synthesis, structure and properties of novel TTF dimers bridged by two trisulfide chains

We synthesized novel TTF dimer molecules in which two TTF moieties are connected to each other by two trisulfide chains. Structure of tetrakis(methylthio) derivative 1 is cyclophane-like one and interplanar distance in the dimer is 3.86 å. 1 shows two pairs of reversible one-electron redox waves (+0.57 and +0.67 V vs. Ag/AgCl in PhCN) and one pair of reversible two-electron redox wave (+1.15 V). The ClO 4 − salt of 1 has 1:2 (Donor:Anion) composition and is an insulator. On the other hand the PF 6 − salt of bis(trimethylene) derivative 2 has one-dimensional columnar donor array with 1:1 composition and shows semiconducting behavior (σ rt = 10 −1 Scm −1).

Synthesis and characterization of mixed valence μ-alkoxo-diiron(II,III) complexes with an unsymmetric dinucleating ligand

A series of dimetal complexes, [M a IIM b III(L)(C 6H 5CO 2) 2](ClO 4) 2, were synthesized ( 2, L = tpdb, M a = M b = Fe; 3, L = Me 4-tpdb, M a = M b = Fe; 4, L = tpdb, M a = Fe, M b = Ga; 5, L = tpdb, M a = Zn, M b = Fe; tpdb = N,N,N′,N′-tetrakis(2-pyridylmethyl)-1,4-diaminobutane-2-olate and Me 4-tpdb = N,N,N′,N′-tetrakis[2-(6-methylpyridyl)methyl]-1,4-diaminobutane-2-olate). These dinucleating ligands provide an unsymmetric bridging back born at two metal centers, forming five- and six-membered chelate rings in a bridging skeleton. Complex 2 afforded two types of crystal ( 2a ( 2·3CH 3CN) and 2b ( 2·1.5H 2O)) suitable for X-ray analyses; 2a crystallizes in the P2 12 12 1 space group with unit cell parameters a = 18.523(3), b = 18.871(3), c = 14.838(5) Å, and Z = 4; 2b crystallizes in the P2 1/ c space group with unit cell parameters a = 25.343(5), b = 15.152(2), c = 48.035(7) Å, β = 91.53(2)°, and Z = 16. 2a contains only one molecule in an asymmetric unit, whereas 2b contains four distinct molecules in an asymmetric unit. Crystal structures showed that all the dinuclear complex cations in 2a and 2b consist of two distinct iron centers which are triply bridged by the alkoxide oxygen of tpdb and two benzoate groups. The Fe III ion tends, preferentially, to occupy a site which has a five-membered chelate ring in the bridging skeleton. There are four distinct complex cations in 2b consisting of two enantiomeric pairs with respect to an asymmetric carbon atom with a skew boat conformation in the six-membered chelate ring, and with a boat conformation in the six-membered chelate ring, respectively. The Mössbauer spectrum of a powdered sample of 2b at 78 K showed three quadrupole doublets; one is due to Fe III centers and the other two are due to Fe II centers. The latter two appear to correspond to two types of conformational isomer found for 2b. The Mössbauer spectra of 2b and 3 at room temperature suggested that, in 2b, the fast electron exchange between Fe II and Fe III begins to occur whereas, in 3, the electron is localized within the Mössbauer time scale. 2 exhibited three absorption bands at 18 970 cm −1 ( ɛ = 338 mol −1 dm 3 cm −1), 12 900 cm −1 ( ɛ = 284 mol −1 dm 3 cm −1) and 7650 cm −1 ( ɛ = 550 mol −1 dm 3 cm −1). The first and third bands are assignable to the intervalence charge transfer transition from t 2g orbitals in the Fe II center to e g and t 2g orbitals in the Fe III center, respectively. Two reversible one-electron redox waves corresponding to the Fe IIFe III/Fe IIFe II and Fe IIIFe III/Fe IIFe III couples were observed at −110 and 620 mV versus SCE for 2 by cyclic voltammetry, indicating that unsymmetric tpdb stabilizes substantially the mixed valence state.

Electron Acceptors of the Fluorene Series. 7.1 2,7-Dicyano-4,5-dinitro-9-X-fluorenes: Synthesis, Cyclic Voltammetry, Charge Transfer Complexation with N-Propylcarbazole in Solution, and X-ray Crystal Structures of Two Tetrathiafulvalene Complexes

The synthesis and physical properties of a series of novel fluorene π-electron acceptors (7−9) are described. Cyclic voltammograms of 7 and 8 exhibit three separate reversible (or quasi-reversible) one-electron redox waves, characteristic of strong electron acceptors. Spectroelectrochemical experiments show the appearance in the long-wavelength visible region of absorption bands at appropriate potentials which were attributed to the transformations A → A•- and A•- → A2-. Charge-transfer complexation with N-propylcarbazole in dioxane shows the formation of 1:1 complexes with parameters characteristic for other fluorene acceptors. The single-crystal X-ray structures of 1:1 charge-transfer complexes of tetrathiafulvalene with the electron acceptor 8 and with the strongest fluorene acceptor 1f both show ··A···D···A···D·· stacking in the crystal.

Thiophene-Functionalized TTF pi-Electron Donors as Potential Precursors to Conducting Polymers and Organic Metals: Synthesis, Properties, Structure, and Electropolymerization Studies.

The synthesis and physical properties of a series of novel thiophene-substituted TTF electron donors (6a-d) are described. The cyclic voltammograms of 6a-d exhibited two reversible one-electron redox waves, characteristic of TTF derivatives. Electropolymerization studies on compound 6a in nitrobenzene indicate that no polymer formed on the working electrode, but a blue-colored intermediate was observed diffusing away from the electrode. In addition, the single-crystal X-ray structure of compound 6d indicates that the central five-membered C(3)S(2) rings are buckled and the ethylenedithiolo fragment adopts a twisted chair conformation. The pendant thiophene moieties are highly flexible, and short intermolecular interactions of 3.49 Å (S.S) and 3.45 Å (S.C) exist in the unit cell, resulting in the formation of a chain structure along the c-axis.

Electrochemical studies of N-phenylaza-15-crown-5

The electrochemical oxidation of the ionophoric macrocycle N-phenylaza-15-crown-5 has been investigated in acetonitrile. For a 1 mmol dm −3 solution of N-phenylaza-15-crown-5, cyclic voltammetry revealed that the mechanism followed that of N, N-dimethyl-aniline, the initial one-electron irreversible oxidation leading to dimerisation at the para position. Constant potential electrolysis in the presence of pyridine allowed stoichiometric electrogeneration of the dimer in solution; subsequent cyclic voltammetry showing two reversible one-electron redox waves ( E f = 0.57 and 0.70 V vs. SSCE) to the dimer radical cation and quinoidal dication respectively. Cyclic voltammetric investigations revealed that both the N-phenylaza-15-crown-5 irreversible oxidation wave and the reversible N-phenylaza-15-crown-5 neutral dimer-to-radical cation redox wave were sensitive to the binding of sodium and magnesium guest cations at the macrocyclic coordinating sites. Thus shifts to more positive potentials were found on titrimetric addition of these cations, the higher charge:radius ratio of the magnesium cation guest producing the most dramatic effect.

Syntheses and structures of mixed-ligand tetrairon-sulfur clusters, [Cp′ 2(Ph 2C 2S 2) 2Fe 4S 4](PF 6) and [Cp′ 3(Ph 2C 2S 2)Fe 4S 5](PF 6) n ( n=1 and 2) (Cp′η 5-C 5Me 5). Structural change of the clusters accompanying electron transfer reactions

The cyclic voltammogram (CV) of the mixed-ligand cubane-type cluster Cp′ 2(Ph 2C 2S 2) 2Fe 4S 4 ( 4) exhibits four reversible one-electron redox waves, corresponding to +2/+1, +1/0, 0/−1, and −1/−2 charged cluster couples. The CV of the mixed-ligand cubane-like cluster Cp′ 3(Ph 2C 2S 2)Fe 4S 5 ( 5) exhibits four reversible one-electron redox waves, corresponding to +3/+2, + 2/+ 1, + 1/0, and 0/−1 charged cluster couples. Oxidized clusters, [ 4](PF 6)·CH 2Cl 2, [ 5](PF 6)· 2Me 2CO and [ 5](PF 6) 2·Me 2CO, were synthesized by chemical and/of electrochemical methods. The structures of these three salts were determined by X-ray crystallography and compared with those of the parent clusters 4 and 5. Both clusters 4 and 5 shrink as they are oxidized, indicating that the electrons are removed from antibonding orbitals. The crystallographic data are as follows: [ 4](PF 6)·CH 2Cl 2: orthorhombic, Pna2 1 with a = 17.259(3), b = 25.682(4), c = 12.628(2) Å, V= 5597(2) Å 3, Z = 4 and R = 0.066; [ 5](PF 6)·2Me 2CO: triclinic, P 1 with a = 14.112(4), b=17.712(3), c=13.325(4) Å, α= 108.08(2), β= 114.74(3), γ=84.00(1) o, V=2874(1) Å 3, Z=2 and R=0.066; [ 5](PF 6) 2·Me 2CO: triclinic, P 1 with a=14.985(1), b=15.540(1), c=12.951(1) Å, α=93.40(2), β=95.04(1), γ=96.76(1) o, V=2976(1) Å 3, Z=2 and R=0.056.