Low-lying electronic states of M(3)O(9)(-) and M(3)O(9)(2-) (M = Mo, W)

Multiple low-lying electronic states of M(3)O(9)(-) and M(3)O(9)(2-) (M = Mo, W) arise from the occupation of the near-degenerate low-lying virtual orbitals in the neutral clusters. We used density functional theory (DFT) and coupled cluster theory (CCSD(T)) with correlation consistent basis sets to study the structures and energetics of the electronic states of these anions. The adiabatic and vertical electron detachment energies (ADEs and VDEs) of the anionic clusters were calculated with 27 exchange-correlation functionals including one local spin density approximation functional, 13 generalized gradient approximation (GGA) functionals, and 13 hybrid GGA functionals, as well as the CCSD(T) method. For M(3)O(9)(-), CCSD(T) and nearly all of the DFT exchange-correlation functionals studied predict the (2)A(1) state arising from the Jahn-Teller distortion due to singly occupying the degenerate e' orbital to be lower in energy than the (2)A(1)' state arising from singly occupying the nondegenerate a(1)' orbital. For W(3)O(9)(-), the (2)A(1) state was predicted to have essentially the same energy as the (2)A(1)' state at the CCSD(T) level with core-valence correlation corrections included and to be higher in energy or essentially isoenergetic with most DFT methods. The calculated VDEs from the CCSD(T) method are in reasonable agreement with the experimental values for both electronic states if estimates for the corrections due to basis set incompleteness are included. For M(3)O(9)(2-), the singlet state arising from doubly occupying the nondegenerate a(1)' orbital was predicted to be the most stable state for both M = Mo and W. However, whereas M(3)O(9)(2-) was predicted to be less stable than M(3)O(9)(-), W(3)O(9)(2-) was predicted to be more stable than W(3)O(9)(-).     

The synthesis,molecular, crystal,and electronic structures of [ReBr2(O)(OCH3)(PPh3)2]

[ReBr₂(O)(OCH₃)(PPh₃)₂] has been obtained in the reaction of [ReBr₃O(PPh₃)₂] or [ReBr₂(η²-N₂COPh-N′,O)(PPh₃)₂] with an excess of methanol. [ReBr₂O(OMe)(PPh₃)₂] crystallizes in the triclinic space group P-1. The complex was characterized by infrared, UV-Vis, and ¹H NMR spectra. The electronic structure of the obtained compound has been calculated using the DFT/TD–DFT method.     

Tribromohydroxyphosphonium hexafluorometalate: synthesis, spectroscopic characterization, and crystal structure of Br(3)POH(+)AsF(6)(-)

The reaction of tribromophosphine oxide in the superacidic systems XF/MF(5) (X = H, D; M = As, Sb) leads to tribromohydroxyphosphonium hexafluorometalates. The structure was successfully elucidated in the case of tribromohydroxyphosphonium hexafluoroarsenate. Br(3)POH(+)AsF(6)(-) crystallizes in the orthorhombic space group Pnma (No. 53 with a = 1292.5(1) pm, b = 871.6(1) pm, and c = 845.0(1) pm) with four formula units per cell. The Raman, IR, (1)H NMR, and (31)P NMR spectra of Br(3)POX(+)MF(6)(-) (X = H, D; M = As, Sb) are reported.     

Synthesis,structure, and magnetic properties of the fullerene-based ferromagnets Eu3C70 and Eu9C70

Intercalation of C(70) with europium affords two kinds of magnetic compounds, a canted antiferromagnet Eu(x)C(70) (x approximately 3) and a ferromagnet Eu(x)C(70) (x approximately 9) with transition temperatures (T(C)) of 5 and 38 K, respectively. The Curie constants in the paramagnetic phase and the saturation moment in the ferromagnetic phase are both understood by the full moment of Eu(2+) for both systems. The structure of Eu(3)(-)(delta)C(70) (delta approximately 0.27) is pseudo-monoclinic, derived by a simple deformation of the parent face-centered cubic (fcc) structure. Eu(9)(-)(delta)C(70) (delta approximately 0.2) forms an fcc structure, in which cuboctahedral clustering of Eu(2+) ions is observed in the enhanced size octahedral holes. The observed T(C) of the Eu(9)(-)(delta)C(70) ferromagnet is comparable to or larger than those of simple binary Eu-based ferromagnets, such as Eu chalcogenides or carbides, despite the low atomic ratio of Eu in the chemical formulas. This can be understood by the short Eu(2+)-Eu(2+) distances and high coordination numbers permitted by the multiple occupation by Eu(2+) ions of the expanded octahedral interstitial sites in higher fullerene-based solids.     

3He NMR study of (3)He@C(60)H(6) and (3)He@C(70)H(2)(-)(10)

The (3)He NMR of (3)He@C(60)H(6), (3)He@C(70)H(2), (3)He@C(70)H(4), (3)He@C(70)H(8), and (3)He@C(70)H(10) have been investigated. A new, unidentified C(60)H(6) isomer has been found by using (3)He NMR. (3)He@C(70)H(10) shows the most downfield-shifted (3)He NMR resonance among the neutral C(70) derivatives.     

[Co(1,10-phen)(H_2O)(VO_3)_2]的水热合成、结构及电化学性质

采用水热方法并以邻菲啉为模板剂合成了一种过渡金属配合物连接的无机-有机层状结构的多金属钒酸盐Co(1,10-phen)(H2O)(VO3)2,该化合物经过X-射线单晶衍射、元素分析、红外光谱表征和热失重分析,并用循环伏安法研究了标题化合物的电化学性质.     

Synthesis,molecular and electronic structure of [ReCl2(N2COPh)(C4N2H4)(PPh3)2]

A new organodiazenido rhenium complex, [ReCl₂(N₂COPh)(C₄N₂H₄)(PPh₃)₂] has been obtained from the direct reaction of [ReCl₂(η²–N₂COPh–N′,O)(PPh₃)₂] with pyrazine in acetone. The complex has been characterized by spectroscopic methods and its structure determined using single-crystal X-ray diffraction techniques.     

Synthesis, molecular and electronic structure of U(V)(O)[N(SiMe3)2]3

Addition of 1 equiv of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to U(NR(2))(3) in hexanes affords U(O)(NR(2))(3) (2), which can be isolated in 73% yield. Complex 2 is a rare example of a terminal U(V) oxo complex. In contrast, addition of 1 equiv of Me(3)NO to U(NR(2))(3) (R = SiMe(3)) in pentane generates the U(IV) bridging oxo [(NR(2))(3)U](2)(μ-O) (3) in moderate yields. Also formed in this reaction, in low yield, is the U(IV) iodide complex U(I)(NR(2))(3) (4). The iodide ligand in 4 likely originates from residual NaI, present in the U(NR(2))(3) starting material. Complex 4 can be generated rationally by addition of 0.5 equiv of I(2) to a hexane solution of U(NR(2))(3), where it can be isolated in moderate yield as a tan crystalline solid. The solid-state molecular structures and magnetic susceptibilities of 2, 3, and 4 have been measured. In addition, the electronic structures of 2 and 3 have been investigated by density functional theory (DFT) methods.     

Regioselective Oxazolination of C(70)(2-) and Formation of cis-1 C(70) Adduct with Respect to the Apical Pentagon

Oxazolination of C(70) has been achieved via the aerobic oxidation of C(70)(2-) in the presence of PhCN. Only one C(70) oxazoline regioisomer (1) is obtained, indicating that the oxazolination of C(70)(2-) occurs with an unusual regioselectivity. Further benzylation of 1(2-) with benzyl bromide leads to the formation of the first cis-1 C(70) derivative with respect to the apical pentagon (2), as shown by the X-ray single-crystal structure and various spectral characterizations. The structure of the obtained C(70) oxazoline (1) is resolved with H/D labeling benzylation and HMBC (heteronuclear multiple bond coherence) NMR on the basis of the structure of 2. The result shows that for compound 1, the O atom is selectively bonded to the C1, while the N atom is bonded to the C2 of C(70). The exhibited regioselectivity for the orientation of oxazolino group on C(70) is further rationalized with computational calculations, and a reaction mechanism for the oxazolination of C(70)(2-) is proposed.     

Synthesis,structure, and magnetic properties of the single-molecule magnet [Ni(21)(cit)(12)(OH)(10)(H(2)O)(10)](16-)

The preparation of two new compounds containing the cluster [Ni(21)(cit)(12)(OH)(10)(H(2)O)(10)](16-) is presented, together with a detailed magnetic investigation of one of the compounds. We found that this cluster shows an unexpected stability and that it exists as different stereoisomers. Compound 1 contains the achiral cluster with a Delta-Lambda configuration, and compound 2 contains a pair of enantiomeric clusters with the configurations Delta-Delta and Lambda-Lambda, respectively. Magnetic measurements of 1 in the millikelvin range were necessary to determine the spin ground state of S = 3, and they also revealed a magnetic anisotropy within the ground state. A frequency-dependent out-of-phase signal was found in alternating current susceptibility measurements at very low temperatures, which indicates a slow relaxation of the magnetization. Thus, individual molecules are acting as single magnetic units, which is a rare phenomenon for nickel clusters. The energy barrier exhibited by compound 1 has been calculated to be 2.9 K.     

Subtle role of polyatomic anions in molecular construction: structures and properties of AgX bearing 2,4'-thiobis(pyridine) (X(-) = NO(3)(-), BF(4)(-), ClO(4)(-), PF(6)(-), CF(3)CO(2)(-), and CF(3)SO(3)(-))

Studies on the subtle effects and roles of polyatomic anions in the self-assembly of a series of AgX complexes with 2,4'-Py(2)S (X(-) = NO(3)(-), BF(4)(-), ClO(4)(-), PF(6)(-), CF(3)CO(2)(-), and CF(3)SO(3)(-); 2,4'-Py(2)S = 2,4'-thiobis(pyridine)) have been carried out. The formation of products appears to be primarily associated with a suitable combination of the skewed conformers of 2,4'-Py(2)S and a variety of coordination geometries of Ag(I) ions. The molecular construction via self-assembly is delicately dependent upon the nature of the anions. Coordinating anions afford the 1:1 adducts [Ag(2,4'-Py(2)S)X] (X(-) = NO(3)(-) and CF(3)CO(2)(-)), whereas noncoordinating anions form the 3:4 adducts [Ag(3)(2,4'-Py(2)S)(4)]X(3) (X(-) = ClO(4)(-) and PF(6)(-)). Each structure seems to be constructed by competition between pi-pi interactions of 2,4'-Py(2)S spacers vs Ag.X interactions. For ClO(4)(-) and PF(6)(-), an anion-free network consisting of linear Ag(I) and trigonal Ag(I) in a 1:2 ratio has been obtained whereas, for the coordinating anions NO(3)(-) and CF(3)CO(2)(-), an anion-bridged helix sheet and an anion-bridged cyclic dimer chain, respectively, have been assembled. For a moderately coordinating anion, CF(3)SO(3)(-), the 3:4 adduct [Ag(3)(2,4'-Py(2)S)(4)](CF(3)SO(3))(3) has been obtained similarly to the noncoordinating anions, but its structure is a double strand via both face-to-face (pi-pi) stackings and Ag.Ag interactions, in contrast to the noncoordinating anions. The anion exchanges of [Ag(3)(2,4'-Py(2)S)(4)]X(3) (X(-) = BF(4)(-), ClO(4)(-), and PF(6)(-)) with BF(4)(-), ClO(4)(-), and PF(6)(-) in aqueous media indicate that a [BF(4)(-)] analogue is isostructural with [Ag(3)(2,4'-Py(2)S)(4)]X(3) (X(-) = ClO(4)(-) and PF(6)(-)). Furthermore, the anion exchangeability for the noncoordinating anion compounds and the X-ray data for the coordinating anion compounds establish the coordinating order to be NO(3)(-) > CF(3)CO(2)(-) > CF(3)SO(3)(-) > PF(6)(-) > ClO(4)(-) > BF(4)(-).     

Band structure and electronic properties of lithium azide (LiN3)

Ab initio Hartree–Fock band structure and molecular calculations have been performed to study the electronic structure of LiN₃ in a monoclinic C 2/m crystal structure. The total energy, band structure, density of states, and charge densities are computed. The calculated lattice energy (energy to separate the ions infinitely apart) of 8.6 eV agrees very well with 8.45 eV deduced from Madelung and London polarizability energies. The calculated split of the N 1s core bands of 5.0 eV compares favorably with the experimental X-ray photoelectron value of 4.4 eV. This good agreement is not contributed to crystalline environment effects as proposed in earlier MO studies of N where the best values obtained were 5.1, 5.8, and 6.3 eV, but to the quality of the nitrogen core basis set. The calculated valence density of states supports one of two competing interpretations that peak III observed in the X-ray photoelectron spectrum arises from contaminations or other extrinsic states.     

Capturing C90 Isomers as CF3 Derivatives: C90(30)(CF3)14, C90(35)(CF3)16/18, and C90(45)(CF3)16/18

High‐temperature trifluoromethylation of a C₉₀ isomeric mixture with CF₃I followed by HPLC separation of C₉₀(CF₃)_n isomers resulted in the isolation of several individual C₉₀(CF₃)_14?18 compounds. Single crystal X‐ray diffraction with the use of synchrotron radiation resulted in the structure determination of C₉₀(30)(CF₃)₁₄, C₉₀(35)(CF₃)_16/18, and C₉₀(45)(CF₃)_16/18. Their addition patterns are discussed and compared with the known isomers C₉₀(30)(CF₃)₁₈ and C₉₀(35)(CF₃)₁₄, respectively. The presence of the most stable C₉₀ isomer, C₉₀(45), in the fullerene soot has been confirmed for the first time.     

First example of mu(3)-sulfido bridged mixed-valent triruthenium complex triangle Ru(III)(2)Ru(II)(O,O-acetylacetonate)(3)(mu-O,O,gamma-C-acetylacetonate)(3)(mu(3)-S) (1) incorporating simultaneous O,O- and gamma-C-bonded bridging acetylacetonate units. Synthesis,crystal structure,and spectral and redox properties

The reaction of mononuclear ruthenium precursor [Ru(II)(acac)(2)(CH(3)CN)(2)] (acac = acetylacetonate) with the thiouracil ligand (2-thiouracil, H(2)L(1) or 6-methyl -2-thiouracil, H(2)L(2)) in the presence of NEt(3) as base in ethanol solvent afforded a trinuclear triangular complex Ru(3)(O,O-acetylacetonate)(3)(mu-O,O,gamma-C-acetylacetonate)(3)(mu(3)-sulfido) (1). In 1, each ruthenium center is linked to one usual O,O-bonded terminal acetylacetonate molecule whereas the other three acetylacetonate units act as bridging functions: each bridges two adjacent ruthenium ions through the terminal O,O-donor centers at one end and via the gamma-carbon center at the other end. Moreover, there is a mu(3)-sulfido bridging in the center of the complex unit, which essentially resulted via the selective cleavage of the carbon-sulfur bond of the thiouracil ligand. In diamagnetic complex 1, the ruthenium ions are in mixed valent Ru(III)Ru(III)Ru(II) state, where the paramagnetic ruthenium(III) ions are antiferromagnetically coupled. The single crystal X-ray structure of 1 showed two crystallographically independent C(3)-symmetric molecules, Ru(3)(O,O-acetylacetonate)(3)(mu-O,O,gamma-C-acetylacetonate)(3)(mu(3)-S) (1), in the asymmetric unit. Bond distances of both crystallographically independent molecules are almost identical, but there are some significant differences in bond angles (up to 6 degrees ) and interplanar angles (up to 8 degrees ). Each ruthenium atom exhibits a distorted octahedral environment formed by four oxygen atoms, two from each of the terminal and bridging acetylacetonate units, one gamma-carbon of an adjacent acetylacetonate ligand, and the sulfur atom in the center of the complex. In agreement with the expected 3-fold symmetry of the complex molecule, the (1)H and (13)C NMR spectra of 1 in CDCl(3) displayed signals corresponding to two types of ligand units. In dichloromethane solvent, 1 exhibited three metal center based successive quasireversible redox processes, Ru(III)Ru(III)Ru(III)-Ru(III)Ru(III)Ru(II) (couple I, 0.43 V vs SCE); Ru(III)Ru(III)Ru(IV)-Ru(III)Ru(III)Ru(III) (couple II, 1.12 V); and Ru(III)Ru(III)Ru(II)-Ru(III)Ru(II)Ru(II) (couple III, -1.21 V). However, in acetonitrile solvent, in addition to the three described couples [(couple I), 0.34 V; (couple II), 1.0 V; (couple III), -1.0], one irreversible oxidative response (Ru(III)Ru(III)Ru(IV) --> Ru(III)Ru(IV)Ru(IV) or oxidation of the coordinated sulfide center) appeared at E(pa), 1.50 V. The large differences in potentials between the successive couples are indicative of strong coupling between the ruthenium ions in the mixed-valent states. Compound 1 exhibited a moderately strong charge-transfer (CT) transition at 654 nm and multiple ligand based intense transitions in the UV region. In the Ru(III)Ru(III)Ru(III) (1(+)) state, the CT band was slightly blue shifted to 644 nm; however, the CT band was further blue shifted to 520 nm on two-electron oxidation to the Ru(III)Ru(III)Ru(IV) (1(2+)) state with a reduction in intensity.     

Preparation, crystallographic characterization and theoretical study of C70(CF3)16 and C70(CF3)18

C70(CF3)16 and C70(CF3)18, the first trifluoromethylated fullerene derivatives to comprise a pair of adjacent CF3 groups, have been isolated from a mixture obtained via reaction of C70 with CF3I, characterized in a single crystal XRD study and theoretically investigated at the DFT level of theory.     

Ferrocene-decorated (phthalocyaninato)(porphyrinato) double- and triple-decker rare earth complexes: synthesis, structure, and electrochemical properties

A series of four mixed (phthalocyaninato)(porphyrinato) rare earth double-decker complexes (Pc)M[Por(Fc)(2)] [Pc = phthalocyaninate; Por(Fc)(2) = 5,15-di(ferrocenyl)-porphyrinate; M = Eu (1), Y (2), Ho (3), Lu (4)] and their europium(III) triple-decker counterpart (Pc)Eu(Pc)Eu[Por(Fc)(2)] (5), each with two ferrocenyl units at the meso-positions of their porphyrin ligands, have been designed and prepared. The double- and triple-decker complexes 1-5 were characterized by elemental analysis and various spectroscopic methods. The molecular structures of two double-deckers 1 and 4 were also determined by single-crystal X-ray diffraction analysis. Electrochemical studies of these novel sandwich complexes revealed two consecutive ferrocene-based one-electron oxidation waves, suggesting the effective electronic coupling between the two ferrocenyl units. Nevertheless, the separation between the two consecutive ferrocene-based oxidation waves increases from 1 to 4, along with the decrease of rare earth ionic radius, indicating the effect of rare earth size on tuning the coupling between the two ferrocenyl units. Furthermore, the splitting between the two ferrocene-based one-electron oxidations for triple-decker 5 is even smaller than that for 1, showing that the electronic interaction between the two ferrocene centers can also be tuned through changing the linking sandwich framework from double-decker to triple-decker. For further understanding of the electronic coupling between ferrocenyl groups, DFT calculation is carried out to clarify the electronic delocalization and the molecular orbital distribution in these double-decker complexes.     

Synthesis and crystal structure of ionic multicomponent complex: ([Cr(I)(PhH)(2)].+))(2)[Co(II)TPP(C(60)(CN)(2))]-[C(60)(CN)(2)](.-).3(o-C(6)H(4)Cl(2)) containing C(60)(CN)(2).- radical anion and sigma-bonded diamagnetic Co(II)TPP(C(60)(CN)(2)) -anion

The ionic multicomponent complex complex: ([Cr(I)(PhH)(2)].+))(2)[Co(II)TPP(C(60)(CN)(2))]-[C(60)(CN)(2)](.-).3(o-C(6)H(4)Cl(2)) (Co(II)TPP: cobalt (II) tetraphenylporphyrin; Cr(PhH)(2): bis(benzene)chromium; o-C(6)H(4)Cl(2): o-dichlorobenzene) containing CoTPP(C(60)(CN)(2)- anion and C(60)(CN)(2).- radical anion was obtained. The complex has the cage structure with channels, which accommodate Cr(I)(PhH)(2)(.+) and o-C(6)H(4)Cl(2) molecules. For the first time the sigma-bonding of Co(II)TPP to the fullerene radical anion with the essentially shortened Co.C(C(60)(CN)(2)) contact of 2.282 A is observed. The sigma-bonding results in the diamagnetism of Co(II)TPP(C(60)(CN)(2))(-) anion. The nonbonded C(60)(CN)(2)(.-) radical anion retains both the C(2)(v)symmetry and the shape of the molecule. The length of the C(triple bond)N bonds is 1.141 and 1.152 A.     

Synthesis,crystal structure,and photoelectric properties of Re(CO)(3)ClL (L = 2-(1-ethylbenzimidazol-2-yl)pyridine)

A novel Re(I) complex, Re(CO)(3)ClL (L = 2-(1-ethylbenzimidazol-2-yl)pyridine), has been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Crystal data for C(17)H(13)ClN(3)O(3)Re: space group, orthorhombic, Pbca; a = 12.713(6) A; b = 15.103(7) A; c = 18.253(8) A; Z = 8. Stable vacuum vapor deposition of the Re complex has been verified by UV-vis and infrared spectroscopy. A two-layer electroluminescent device with configuration of ITO/TPD/Re(CO)(3)ClL/Mg(0.9)Ag(0.1)/Ag has been fabricated, which gave a turn-on voltage of as low as 3 V and a maximum luminance of 113 cd/m(2) at a bias voltage of 10.5 V, and confirmed that the Re complex can function as a bright orange-red emitter and an electron transport material in an electroluminescent device.