Trimerization of alkali dicyanamides M[N(CN)2] and formation of tricyanomelaminates M3[C6N9] (M = K, Rb) in the melt: crystal structure determination of three polymorphs of K[N(CN)2], two of Rb[N(CN)2], and one of K3[C6N9] and Rb3[C6N9] from X-ray powder diffractometry

The alkali dicyanamides M[N(CN)2] (M=K, Rb) were synthesized through ion exchange, and the corresponding tricyanomelaminates M3[C6N9] were obtained by heating the respective dicyanamides. The thermal behavior of the dicyanamides and their reaction to form the tricyanomelaminates were investigated by temperature-dependent X-ray powder diffractometry and thermoanalytical measurements. Potassium dicyanamide K[N(CN)2] was found to undergo four phase transitions: At 136 degrees C the low-temperature modification alpha-K[N(CN)2] transforms to beta-K[N(CN)2], and at 187degrees C the latter transforms to the high-temperature modification gamma-K[N(CN)2], which melts at 232 degrees C. Above 310 degrees C the dicyanamide ions [N(CN)2]- trimerize and the resulting tricyanomelaminate K3[C6N9] solidifies. Two modifications of rubidium dicyanamide have been identified: Even at -25 degrees C, the a form slowly transforms to beta-Rb[N(CN)2] within weeks. Rb[N(CN)2] has a melting point of 190 degrees C. Above 260 degrees C the dicyanamide ions [N(CN)2]- of the rubidium salt trimerize in the melt and the tricyanomelaminate Rb3[C6N9] solidifies. The crystal structures of all phases were determined by powder diffraction methods and were refined by the Rietveld method. alpha-K[N(CN)2] (Pbcm, a = 836.52(1), b = 46.90(1), c =7 21.27(1) pm, Z = 4), gamma-K[N(CN)2] (Pnma, a = 855.40(3), b = 387.80(1), 1252.73(4) pm, Z = 4), and Rb[N(CN)2] (C2/c, a = 1381.56(2), b = 1000.02(1), c = 1443.28(2) pm, 116.8963(6) degrees, Z = 16) represent new structure types. The crystal structure of beta-K[N(CN)2] (P2(1/n), a = -726.92(1), b 1596.34(2), c = 387.037(5) pm, 111.8782(6) degrees, Z = 4) is similar but not isotypic to the structure of alpha Na[N(CN)2]. alpha-Rb[N(CN)2] (Pbcm, a = 856.09(1), b = 661.711(7), c = 765.067(9) pm, Z = 4) is isotypic with alpha-K[N(CN)2]. The alkali dicyanamides contain the bent planar anion [N(CN)2]- of approximate symmetry C2, (average bond lengths: C-N(bridge) 133, C-N(term) 113 pm; average angles N-C-N 170 degrees, C-N-C 120 degrees). K3[C6N9] (P2(1/c), a = 373.82(1), b = 1192.48(5), c = 2500.4(1) pm, beta = 101.406(3) degrees, Z = 4) and Rb,[C6N9] (P2(1/c), a = 389.93(2), b = 1226.06(6), c = 2547.5(1) pm, 98.741(5) degrees, Z=4) are isotypic and they contain the planar cyclic anion [C6N9]3-. Although structurally related, Na3[C6N9] is not isotypic with the tricyanomelaminates M3[C6N9] (M = K, Rb).     

Matrix-isolated Al2OF6(2-) ion in molten and solid LiF/NaF/KF

A Raman spectrum consistent with that expected from an Al2OF6(2-) ion was observed when Na2O was dissolved in a eutectic LiF/NaF/KF (FLINAK) melt at 500 degrees C, which contained a low concentration of either AlF3 or Na3AlF6. Furthermore, it was possible to trap the Al2OF6(2-) ion in the frozen solid and to measure its Raman and IR spectra at 25 degrees C. A number of bands have been detected; among those, the two most characteristic bands of the Al2OF6(2-) ion at 494 (polarized) and 265 cm-1 in the FLINAK melt at 500 degrees C, and those at 509 and 268 (Raman) and approximately 780 to approximately 900 (IR) cm-1 for the compound matrix isolated in solid FLINAK at 25 degrees C. In the absence of added oxide, the dissolved aluminum fluoride was in the form of the octahedral AlF6(3-) ion, which has characteristic Raman bands at 542 and 325 cm-1 in the FLINAK melt at 500 degrees C. Whereas alumina, Al2O3, was found to be essentially insoluble in FLINAK melts, it was possible to dissolve sufficient amounts of Na2O to convert most of the AlF6(3-) to the oxyfluoroaluminate, Al2OF6(2-). These solutions appeared to be metastable with respect to formation of insoluble alumina at higher temperatures. The present results can be compared to previous measurements on alumina dissolved in pure molten cryolite at much higher temperatures, where alumina solubility is low and broad bands due to oxide species are difficult to detect due to overlap with bands from AlF6(3-) and AlF4-.     

Synthesis,structures, and conformational characteristics of calixarene monoanions and dianions

The synthesis, complete characterization, and solid state structural and solution conformation determination of calix[n]arenes (n = 4, 6, 8) is reported. A complete series of X-ray structures of the alkali metal salts of calix[4]arene (HC4) illustrate the great influence of the alkali metal ion on the solid state structure of calixanions (e.g., the Li salt of monoanionic HC4 is a monomer; the Na salt of monoanionic HC4 forms a dimer; and the K, Rb, and Cs salts exist in polymeric forms). Solution NMR spectra of alkali metal salts of monoanionic calix[4]arenes indicate that they have the cone conformation in solution. Variable-temperature NMR spectra of salts HC4.M (M = Li, Na, K, Rb, Cs) show that they possess similar coalescence temperatures, all higher than that of HC4. Due to steric hindrance from tert-butyl groups in the para position of p-tert-butylcalix[4]arene (Bu(t)C4), the alkali metal salts of monoanionic Bu(t)C4 exist in monomeric or dimeric form in the solid state. Calix[6]arene (HC6) and p-tert-butylcalix[6]arene (Bu(t)C6) were treated with a 2:1 molar ratio of M(2)CO(3) (M = K, Rb, Cs) or a 1:1 molar ratio of MOC(CH(3))(3) (M = Li, Na) to give calix[6]arene monoanions, but calix[6]arenes react in a 1:1 molar ratio with M(2)CO(3) (M = K, Rb, Cs) to afford calix[6]arene dianions. Calix[8]arene (HC8) and p-tert-butylcalix[8]arene (Bu(t)()C8) have similar reactivity. The alkali metal salts of monoanionic calix[6]arenes are more conformationally flexible than the alkali metal salts of dianionic calix[6]arenes, which has been shown by their solution NMR spectra. X-ray crystal structures of HC6.Li and HC6.Cs indicate that the size of the alkali metal has some influence on the conformation of calixanions; for example, HC6.Li has a cone-like conformation, and HC6.Cs has a 1,2,3-alternate conformation. The calix[6]arene dianions show roughly the same structural architecture, and the salts tend to form polymeric chains. For most calixarene salts cation-pi arene interactions were observed.     

New metalloligands [M(SC[O]Ph)(4)](-): synthesis and characterization of polymeric [A(MeCN)(x)[M(SC[O]Ph)(4)]] compounds (A = Li,Na and K; M = Ga and In; x = 0-2)

Exploiting the ability of the [M(SC[O]Ph)(4)](-) anion to behave like an anionic metalloligand, we have synthesized [Li[Ga(SC[O]Ph)(4)]] (1), [Li[In(SC[O]Ph)(4)]] (2), [Na[Ga(SC[O]Ph)(4)]] (3), [Na(MeCN)[In(SC[O]Ph)(4)]] (4), [K[Ga(SC[O]Ph)(4)]] (5), and [K(MeCN)(2)[In(SC[O]Ph)(4)]] (6) by reacting MX(3) and PhC[O]S(-)A(+) (M = Ga(III) and In(III); X = Cl(-) and NO(3)(-); and A = Li(I), Na(I), and K(I)) in the molar ratio 1:4. The structures of 2, 4, and 6 determined by X-ray crystallography indicate that they have a one-dimensional coordination polymeric structure, and structural variations may be attributed to the change in the alkali metal ion from Li(I) to Na(I) to K(I). Crystal data for 2 x 0.5MeCN x 0.25H(2)O: monoclinic space group C2/c, a = 24.5766(8) A, b = 13.2758(5) A, c = 19.9983(8) A, beta = 108.426(1) degrees, Z = 8, and V = 6190.4(4) A(3). Crystal data for 4: monoclinic space group P2(1)/c, a = 10.5774(7) A, b = 21.9723(15) A, c = 14.4196(10) A, beta = 110.121(1) degrees, Z = 4, and V = 3146.7(4) A(3). Crystal data for 6: monoclinic space group P2(1)/c, a = 12.307(3) A, b = 13.672(3) A, c = 20.575(4) A, beta = 92.356(4) degrees, Z = 4, and V = 3458.8(12) A(3). The thermal decomposition of these compounds indicated the formation of the corresponding AMS(2) materials.     

Hydrocarbon species mu3-CCH2-, mu3-CCH3 and mu-CHCH3 supported on Ti3O3

Treatment of the mu3-ethylidyne complex [{TiCp*(mu-O)}3(mu3-CMe)](1), (Cp*=eta5-C5Me5) with alkali metal amides leads to the oxoheterometallocubane derivatives [M(mu3-O)3{(TiCp*)3(mu3-CCH2)}] [M = Li (2), Na (3), K (4), Rb (5), Cs (6)] containing the naked carbanion mu3-CCH2-; the addition of triphenylmethanol and tert-butanol to the compounds 2-6 gives rise to the oxoderivatives [{TiCp*(mu-O)}3(mu-CHMe)(OCR3)][R = Me (7), Ph (8)] which show a mu-ethylidene bridge on the surface model Ti3O3.     

Expanding the crystal chemistry of uranyl peroxides: synthesis and structures of di- and triperoxodioxouranium(VI) complexes

Four compounds containing tri- and diperoxodioxouranium(VI) complexes have been synthesized under ambient conditions and structurally characterized. The crystal structures of Na4(UO2)(O2)3(H2O)12 (monoclinic, P21/c, a=6.7883(6) A, b=16.001(2) A, c=16.562(2) A, beta=91.917(2) degrees, V=1797.9(3) A3, Z=4) and Ca2(UO2)(O2)3(H2O)9 (orthorhombic, Pbcn, a=9.576(3) A, b=12.172(3) A, c=12.314(2) A, V=1435.4(6) A3, Z=4) contain clusters of triperoxodioxouranium(VI). These clusters are bonded through a network of H bonding to H2O groups and in the Ca compound by bonds to Ca2+ cations. In the crystal structure of Na2Rb4(UO2)2(O2)5(H2O)14 (orthorhombic, Pbcm, a=6.808(2) A, b=16.888(6) A, c=23.286(8) A, V=2677.5(16) A3, Z=4), triperoxodioxouranium(VI) polyhedra share a peroxide edge, forming dimers of polyhedra of composition (UO2)2(O2)5(6-). Adjacent dimers are linked through bonding to Rb+ cations and by H bonds to H2O groups. The crystal structure of K6[(UO2)(O2)2(OH)]2(H2O)7 (orthorhombic, Pcca, a=15.078(8) A, b=6.669(4) A, c=23.526(13) A, V=2366(2) A3, Z=4) contains diperoxodioxouranium(VI) polyhedra that include two OH groups. These polyhedra share an OH-OH edge, forming dimers of composition (UO2)2(O2)4(OH)2(6-). The dimers are linked by bonds to K+ cations and by H bonding to H2O groups.     

Mixed-metal uranium(VI) iodates: hydrothermal syntheses,structures, and reactivity of Rb[UO(2)(CrO(4))(IO(3))(H(2)O)], A(2)[UO(2)(CrO(4))(IO(3))(2)] (A = K,Rb, Cs), and K(2)[UO(2)(MoO(4))(IO(3))(2)

The reactions of the molecular transition metal iodates A[CrO(3)(IO(3))] (A = K, Rb, Cs) with UO(3) under mild hydrothermal conditions provide access to four new, one-dimensional, uranyl chromatoiodates, Rb[UO(2)(CrO(4))(IO(3))(H(2)O)] (1) and A(2)[UO(2)(CrO(4))(IO(3))(2)] (A = K (2), Rb (3), Cs (4)). Under basic conditions, MoO(3), UO(3), and KIO(4) can be reacted to form K(2)[UO(2)(MoO(4))(IO(3))(2)] (5), which is isostructural with 2 and 3. The structure of 1 consists of one-dimensional[UO(2)(CrO(4))(IO(3))(H(2)O)](-) ribbons that contain uranyl moieties bound by bridging chromate and iodate anions as well as a terminal water molecule to create [UO(7)] pentagonal bipyramidal environments around the U(VI) centers. These ribbons are separated from one another by Rb(+) cations. When the iodate content is increased in the hydrothermal reactions, the terminal water molecule is replaced by a monodentate iodate anion to yield 2-4. These ribbons can be further modified by replacing tetrahedral chromate anions with MoO(4)(2)(-) anions to yield isostructural, one-dimensional [UO(2)(MoO(4))(IO(3))(2)](2)(-) ribbons. Crystallographic data: 1, triclinic, space group P(-)1, a = 7.3133(5) A, b = 8.0561(6) A, c = 8.4870(6) A, alpha = 88.740(1) degrees, beta = 87.075(1) degrees, gamma = 71.672(1) degrees, Z = 2; 2, monoclinic, space group P2(1)/c, a = 11.1337(5) A, b = 7.2884(4) A, c = 15.5661(7) A, beta = 107.977(1) degrees, Z = 4; 3, monoclinic, space group P2(1)/c, a = 11.3463(6) A, b = 7.3263(4) A, c = 15.9332(8) A, beta = 108.173(1) degrees, Z = 4; 4, monoclinic, space group P2(1)/n, a = 7.3929(5) A, b = 8.1346(6) A, c = 22.126(2) A, beta = 90.647(1) degrees, Z = 4; 5, monoclinic, space group P2(1)/c, a = 11.3717(6) A, b = 7.2903(4) A, c = 15.7122(8) A, beta = 108.167(1) degrees, Z = 4.     

Effect of peripheral donor substituents on the binding modes of phosphinomethanide ligands. Synthesis and crystal structures of alkali metal derivatives of an O-functionalised phosphinomethanide ligand

The O-functionalised tertiary phosphine {(Me3Si)2CH}P(C6H4-2-CH2OMe)2 (9) is accessible via the reaction of {(Me3Si)2CH}PCl2 with two equivalents of in situ generated 2-LiC6H4CH2OMe. Phosphine 9 is readily deprotonated by Bu(n)Li to give the lithium phosphinomethanide [[{(Me3Si)2C}P(C6H4-2-CH2OMe)2]Li] (13), which undergoes metathesis reactions with the alkoxides MOR [M = Na, K, R = Bu(t); M = Rb, R = 2-ethylhexyl] to give the heavier alkali metal phosphinomethanides [[{(Me3Si)2C}P(C6H4-2-CH2OMe)2]M]n in good yields [M = Na (14), n= 2; M = K (15), Rb (16), n=[infinity]]. Compounds 9, [{(Me3Si)2CH}P(C6H4-2-CH2OMe)2LiBr]2 (10), and 14-16 have been studied by X-ray crystallography; in the solid state 14 adopts a dimeric structure, whereas 15 and 16 crystallise as one-dimensional polymers.     

Syntheses, crystal structures, and magnetic properties of one-dimensional oxalato-bridged Co(II), Ni(II), and Cu(II) complexes with n-aminopyridine (n = 2-4) as terminal ligand

The reaction of M(ox) x 2H(2)O (M = Co(II), Ni(II)) or K(2)(Cu(ox)(2)) x 2H(2)O (ox = oxalate dianion) with n-ampy (n = 2, 3, 4; n-ampy = n-aminopyridine) and potassium oxalate monohydrate yields one-dimensional oxalato-bridged metal(II) complexes which have been characterized by FT-IR spectroscopy, variable-temperature magnetic measurements, and X-ray diffraction methods. The complexes M(mu-ox)(2-ampy)(2) (M = Co (1), Ni (2), Cu (3)) are isomorphous and crystallize in the monoclinic space group C2/c (No. 15), Z = 4, with unit cell parameters for 1 of a = 13.885(2) A, b = 11.010(2) A, c = 8.755(1) A, and beta = 94.21(2) degrees. The compounds M(mu-ox)(3-ampy)(2).1.5H(2)O (M = Co (4), Ni (5), Cu (6)) are also isomorphous and crystallize in the orthorhombic space group Pcnn (No. 52), Z = 8, with unit cell parameters for 6 of a = 12.387(1), b = 12.935(3), and c = 18.632(2) A. Compound Co(mu-ox)(4-ampy)(2) (7) crystallizes in the space group C2/c (No. 15), Z = 4, with unit cell parameters of a = 16.478(3) A, b = 5.484(1) A, c = 16.592(2) A, and beta = 117.76(1) degrees. Complexes M(mu-ox)(4-ampy)(2) (M = Ni (8), Cu (9)) crystallize in the orthorhombic space group Fddd (No. 70), Z = 8, with unit cell parameters for 8 of a = 5.342(1), b = 17.078(3), and c = 29.469(4) A. All compounds are comprised of one-dimensional chains in which M(n-ampy)(2)(2+) units are sequentially bridged by bis-bidentate oxalato ligands with M.M intrachain distances in the range of 5.34-5.66 A. In all cases, the metal atoms are six-coordinated to four oxygen atoms, belonging to two bridging oxalato ligands, and the endo-cyclic nitrogen atoms, from two n-ampy ligands, building distorted octahedral surroundings. The aromatic bases are bound to the metal atom in cis (1-6) or trans (7-9) positions. Magnetic susceptibility measurements in the temperature range of 2-300 K show the occurrence of antiferromagnetic intrachain interactions except for the compound 3 in which a weak ferromagnetic coupling is observed. Compound 7 shows spontaneous magnetization below 8 K, which corresponds to the presence of spin canted antiferromagnetism.     

Adduct formation between alkali metal ions and anionic LV(V)O(2)(-) (L(2-) = tridentate ONS ligands) species: syntheses, structural investigation, and photochemical studies

Syntheses of alkali metal adducts [LVO(2)M(H(2)O)(n)] (1-7) (M = Na(+), K(+), Rb(+), and Cs(+); L = L(1)(-)L(3)) of anionic cis-dioxovanadium(V) species (LVO(2)(-)) of tridentate dithiocarbazate-based Schiff base ligands H(2)L (S-methyl-3-((5-(R-2-hydroxyphenyl))methyl)dithiocarbazate, R = H, L = L(1); R = NO(2), L = L(2); R = Br, L = L(3)) have been reported. The LVO(2)(-) moieties here behave like an analogue of carboxylate group and have displayed interesting variations in their binding pattern with the change in size of the alkali metal ions as revealed in the solid state from the X-ray crystallographic analysis of 1, 3, 6, and 7. The compounds have extended chain structures, forming ion channels, and are stabilized by strong Coulombic and hydrogen-bonded interactions. The number of coordinated water molecules in [LVO(2)M(H(2)O)(n)] decreases as the charge density on the alkali metal ion decreases (n = 3.5 for Na(+) and 1 for K(+) and Rb(+), while, for Cs(+), no coordinated water molecule is present). In solution, compounds 1-7 are stable in water and methanol, while in aprotic solvents of higher donor strengths, viz. CH(3)CN, DMF and DMSO, they undergo photoinduced reduction when exposed to visible light, yielding green solutions from their initial yellow color. The putative product is a mixed-oxidation (mu-oxo)divanadium(IV/V) species as revealed from EPR, electronic spectroscopy, dynamic (1)H NMR, and redox studies.     

Syntheses and structures of the infinite chain compounds Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14)

The alkali metal/group 4 metal/polychalcogenides Cs(4)Ti(3)Se(13), Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) have been synthesized by means of the reactive flux method at 823 or 873 K. Cs(4)Ti(3)Se(13) crystallizes in a new structure type in space group C(2)(2)-P2(1) with eight formula units in a monoclinic cell at T = 153 K of dimensions a = 10.2524(6) A, b = 32.468(2) A, c = 14.6747(8) A, beta = 100.008(1) degrees. Cs(4)Ti(3)Se(13) is composed of four independent one-dimensional [Ti(3)Se(13)(4-)] chains separated by Cs(+) cations. These chains adopt hexagonal closest packing along the [100] direction. The [Ti(3)Se(13)(4-)] chains are built from the face- and edge-sharing of pentagonal pyramids and pentagonal bipyramids. Formal oxidation states cannot be assigned in Cs(4)Ti(3)Se(13). The compounds Rb(4)Ti(3)S(14), Cs(4)Ti(3)S(14), Rb(4)Hf(3)S(14), Rb(4)Zr(3)Se(14), Cs(4)Zr(3)Se(14), and Cs(4)Hf(3)Se(14) crystallize in the K(4)Ti(3)S(14) structure type with four formula units in space group C(2)(h)()(6)-C2/c of the monoclinic system at T = 153 K in cells of dimensions a = 21.085(1) A, b = 8.1169(5) A, c = 13.1992(8) A, beta = 112.835(1) degrees for Rb(4)Ti(3)S(14);a = 21.329(3) A, b = 8.415(1) A, c = 13.678(2) A, beta = 113.801(2) degrees for Cs(4)Ti(3)S(14); a = 21.643(2) A, b = 8.1848(8) A, c = 13.331(1) A, beta = 111.762(2) degrees for Rb(4)Hf(3)S(14); a = 22.605(7) A, b = 8.552(3) A, c = 13.880(4) A, beta = 110.919(9) degrees for Rb(4)Zr(3)Se(14); a = 22.826(5) A, b = 8.841(2) A, c = 14.278(3) A, beta = 111.456(4) degrees for Cs(4)Zr(3)Se(14); and a = 22.758(5) A, b = 8.844(2) A, c = 14.276(3) A, beta = 111.88(3) degrees for Cs(4)Hf(3)Se(14). These A(4)M(3)Q(14) compounds (A = alkali metal; M = group 4 metal; Q = chalcogen) contain hexagonally closest-packed [M(3)Q(14)(4-)] chains that run in the [101] direction and are separated by A(+) cations. Each [M(3)Q(14)(4-)] chain is built from a [M(3)Q(14)] unit that consists of two MQ(7) pentagonal bipyramids or one distorted MQ(8) bicapped octahedron bonded together by edge- or face-sharing. Each [M(3)Q(14)] unit contains six Q(2)(2-) dimers, with Q-Q distances in the normal single-bond range 2.0616(9)-2.095(2) A for S-S and 2.367(1)-2.391(2) A for Se-Se. The A(4)M(3)Q(14) compounds can be formulated as (A(+))(4)(M(4+))(3)(Q(2)(2-))(6)(Q(2-))(2).     

Syntheses, structures, ionic conductivities, and magnetic properties of three new transition-metal borophosphates Na5(H3O){M(II)3[B3O3(OH)]3(PO4)6}.2H2O (M(II) = Mn, Co, Ni)

Three new open-framework transition-metal borophosphates Na5(H3O){M(II)3[B3O3(OH)]3(PO4)6}.2H2O (M(II) = Mn, Co, Ni) (denoted as MBPO-CJ25) have been synthesized under mild hydrothermal conditions. Single-crystal X-ray diffraction analyses reveal that the three compounds possess isostructural three-dimensional (3D) open frameworks with one-dimensional 12-ring channels along the [001] direction. Notably, the structure can also be viewed as composed of metal phosphate layers [M(II)(PO4)2]4- with Kagomé topology, which are further connected by [B3O7(OH)] triborates, giving rise to a 3D open framework. The guest water molecules locate in the 12-ring channels. Partial Na+ ions reside in the 10-ring side pockets within the wall of the 12-ring channels, and the other Na+ ions and protonated water molecules locate in the 6-ring windows delimited by MO6 and PO4 polyhedra to compensate for the negative charges of the anionic framework. These compounds show a high thermal stability and are stable upon calcinations at ca. 500 degrees C. Ionic conductivities, due to the motion of Na+ ions, are measured for these three compounds. They have similar activation energies of 1.13-1.25 eV and conductivities of 2.7 x 10(-7)-9.9 x 10(-7) S cm(-1) at 300 degrees C. Magnetic measurements reveal that there are very weak antiferromagnetic interactions among the metal centers of the three compounds. Crystal data: MnBPO-CJ25, hexagonal, P6(3)/m (No. 176), a = 11.9683(5) A, c = 12.1303(6) A, and Z = 2; CoBPO-CJ25, hexagonal, P6(3)/m (No. 176), a = 11.7691(15) A, c = 12.112(2) A, and Z = 2; NiBPO-CJ25, hexagonal, P6(3)/m (No. 176), a = 11.7171(5) A, c = 12.0759(7) A, and Z = 2.     

A joint experimental and theoretical study of cation-pi interactions: multiple-decker sandwich complexes of ferrocene with alkali metal ions (Li+, Na+, K+, Rb+, Cs+)

A systematic study of cation-pi interactions between alkali metal ions and the cyclopentadienyl ring of ferrocene is presented. The alkali metal (Li+, Na+, K+, Rb+, Cs+) salts of the ditopic mono(pyrazol-1-yl)borate ligand [1,1'-fc(BMe2pz)2]2- crystallize from dimethoxyethane as multiple-decker sandwich complexes with the M+ ions bound to the pi faces of the ferrocene cyclopentadienyl rings in an eta5 manner (fc = (C5H4)2Fe; pz = pyrazolyl). X-ray crystallography of the lithium complex reveals discrete trimetallic entities with each lithium ion being coordinated by only one cyclopentadienyl ring. The sodium salt forms polyanionic zigzag chains where each Na+ ion bridges the cyclopentadienyl rings of two ferrocene moieties. Linear columns [-CpR-Fe-CpR-M+-CpR-Fe-CpR-M+-](infinity) (R = [-BMe2pz]-) are established by the K+, Rb+, and Cs+ derivatives in the solid state. According to DFT calculations, the binding enthalpies of M+-eta5(ferrocene) model complexes are about 20% higher as compared to the corresponding M+-eta6(benzene) aggregates when M+ = Li+ or Na+. For K+ and Rb+, the degree of cation-pi interaction with both aromatics is about the same. The binding sequence along the M+-eta5(ferrocene) series follows a classical electrostatic trend with the smaller ions being more tightly bound.     

K4H2[PMo9V3O40]·10H2O的合成及其晶体结构

采用低温技术,用X射线单晶衍射法测定了标题化合物的结构。晶体属P4/mnc空间群,=12.515(3),c=17.636(7)A,Z=2.用788个独立可观测反射精修所有结构参数得R=0.061.钼钒磷杂多酸阴离子中,PO4四面体是无序的,P-O键长1.54A.M(Mo,V)是6配位,M-O键长1.62-2.48A,K是7配位,K-O键长2.84-3.10A。     

Verdazyl radicals as oligopyridine mimics: structures and magnetic properties of M(II) complexes of 1,5-dimethyl-3-(2,2'-bipyridin-6-yl)-6-oxoverdazyl (M = Mn,Ni, Cu,Zn)

The verdazyl radical 1,5-dimethyl-3-(2,2'-bipyridin-6-yl)-6-oxoverdazyl (3) was prepared, and its homoleptic metal complexes M(3)(2)(2+).2X(-) (5, M = Mn(II); 6, M = Ni(II); 7, M = Cu(II); 8, M = Zn(II); X = ClO(4), PF(6)) were characterized by single-crystal X-ray diffraction and variable-temperature magnetic susceptibility measurements. Relevant crystallographic parameters are as follows: 5, monoclinic space group Pna2(1), a = 18.755(4) A, b = 11.154(3) A, c = 16.594(4) A, alpha = 90.00 degrees, beta = 90.00 degrees, gamma = 90.00 degrees, V = 3471.4(13) A(3), and Z = 4; 7, triclinic space group Ponedblac;, a = 9.4638(18) A, b = 9.8442(19) A, c = 18.769(4) A, alpha = 103.746(3) degrees, beta = 92.925(3) degrees, gamma = 94.869(3) degrees, V = 1687.8(6) A(3), and Z = 2; 8, triclinic space group Ponedblac;, a = 9.4858(14) A, b = 9.7919(14) A, c = 18.889(3) A, alpha = 104.196(3) degrees, beta = 92.855(3) degrees, gamma = 94.216(3) degrees, V = 1692.1(4) A(3), and Z = 2. In all cases, the two verdazyl-based ligands bind almost perpendicular to each other in meridional positions, yielding pseudooctahedral metal complexes whose general structural features are strongly reminiscent of metal bis(terpyridine) complexes. The intramolecular metal-verdazyl magnetic exchange coupling is strongly ferromagnetic in 6 (J(Ni-vd) = +240 cm(-1)), and strongly antiferromagnetic in 5 (J(Mn-vd) = -93 cm(-1)). Complex 7 exhibits weak ferromagnetic coupling (J(Cu-vd) = -4.5 cm(-1)). Intramolecular radical-radical coupling in the zinc complex 8 was found to be weakly antiferromagnetic (J(vd-vd) = -8 cm(-1)). Intramolecular radical-radical exchange was generally weak in the four metal complexes, ranging from -10 cm(-1) (for 5) to +2 cm(-1) (for 7). The low-temperature magnetic behavior of 7 and 8 is complex, possibly arising from a combination of intra- and intermolecular interactions.     

Tetracyanoborate salts M[b(CN)4] with M = singly charged cations: properties and structures

A series of tetracyanoborate salts M[B(CN)4] with the singly charged cations of Li+, Na+, Rb+, Cs+, [NH4]+, Tl+, and Cu+ as well as the THF solvate tetracyanoborates Na[B(CN)4] x THF and [NH4][B(CN)4] x THF were synthesized and their X-ray structures, vibrational spectra, solubilities in water, and thermal stabilities determined and compared with already known M[B(CN)4] salts. Crystallographic data for these compounds are as follows: Na[B(CN)4], cubic, Fd3m, a = 11.680(1) A, Z= 8; Li[B(CN)4], cubic, P43m, a = 5.4815(1) A, Z= 1; Cu[B(CN)4], cubic, P43m, a = 5.4314(7) A, Z= 1; Rb[B(CN)4], tetragonal, /4(1)/a, a = 7.1354(2) A, c= 14.8197(6) A, Z= 4; Cs[B(CN)4], tetragonal, /4(1)/a, a = 7.300(2) A, c = 15.340(5) A, Z= 4; [NH4][B(CN)4], tetragonal, /4(1)/a, a = 7.132(1) A, c = 14.745(4) A, Z= 4; Tl[B(CN)4], tetragonal, /4(1)/a, a = 7.0655(2) A, c = 14.6791(4) A, Z= 4; Na[B(CN)4] x THF, orthorhombic, Pnma, a = 13.908(3) A, b = 9.288(1) A, c = 8.738(1) A, Z= 4; [NH4][B(CN)4] x THF, orthorhombic, Pnma, a = 8.831(1) A, b = 9.366(2) A, c = 15.061(3) A, Z= 4. The cubic Li+, Na+, and Cu+ salts crystallize in a structure consisting of two interpenetrating independent tetrahedral networks of M cations and [B(CN)4]- ions. The compounds with the larger countercations (Rb+, Cs+, Tl+, and [NH4]+) crystallize as tetragonal, also with a network arrangement. The sodium and ammonium salts with the cocrystallized THF molecules are both orthorhombic but are not isostructural. In the vibrational spectra the two CN stretching modes A1 and T2 coincide in general and the band positions are a measure for the strength of the interionic interaction. An interesting feature in the Raman spectrum of the copper salt is the first appearance of two CN stretching modes.     

Synthesis and Structural Investigation of a Complete Series of Brightly Colored Alkali Metal 1,3-Dimethylviolurates

A complete series of alkali metal 1,3-dimethylviolurates M(Me₂Vio) was synthesized and fully characterized. The title compounds M(Me₂Vio)(H₂O) [M = Li ( 3 ), Na ( 4 )], K(Me₂Vio)(H₂O)_0.5 ( 5 ) and M(Me₂Vio) [M = Rb ( 6 ), Cs ( 7 )] were prepared by neutralizing 1,3-dimethylvioluric acid (= HMe₂Vio; 2 ) with 1 equiv. of the corresponding metal hydroxides MOH. The resulting salts exhibit striking colors ranging from orange-red ( 3 ) through purple ( 4 , 5 ) to bright blue ( 6 , 7 ). In contrast to the monohydrate 4 , the classical synthesis of sodium 1,3-dimethylviolurate from 1,3-dimethylbarbituric acid and NaNO₂ afforded the purple trihydrate Na(Me₂Vio)(H₂O)₃ ( 4a ). All new compounds have been fully characterized by their IR and NMR (¹H, ¹³C) spectra as well as elemental analyses. X-ray crystal structure determination revealed that the title compounds exist as one- (Li, Na), two- (K, Cs), or three-dimensional (Rb) coordination polymers in the solid state.     

Synthesis and characterization of A3Na10Sn23 (A = Cs, Rb, K) with a new clathrate-like structure and of the chiral clathrate Rb5Na3Sn25

Four new compounds Cs17.4(1)Na60.6(1)Sn138 (1), Rb19.1(1)Na58.9(1)Sn138 (2), K21.3(1)Na56.7(1)Sn138 (3), and Rb20Na12Sn100 (4) were synthesized by fusion of the corresponding elements. The structures were determined by single-crystal X-ray diffraction. Compounds 1-3 are isostructural and crystallize in a new structure type (rhombohedral, R3m, Z = 1, a = 12.4567(9) A, c = 51.533(3) A for 1; a = 12.465(1) A, c = 51.085(3) A for 2; a = 12.456(2) A, c = 50.559(4) A for 3). The structure contains layers of fused pentagonal dodecahedra of tin that alternate with layers of isolated tin tetrahedra. It is an intergrowth between the structure of clathrate-II (A24Sn136) with the same layers of pentagonal dodecahedra and the Zintl phase ASn with Sn4(4-) tetrahedra. Compound 4 is a new chiral clathrate (cubic, P4(1)32, Z = 1; a = 16.4127(7) A) with stoichiometry that corresponds to an electronically balanced Zintl phase.     

A new class of hybrid materials via salt inclusion: novel copper(II) arsenates Na(5)ACu(4)(AsO(4))(4)Cl(2) (A = Rb,Cs) composed of alternating covalent and ionic lattices

Two novel copper(II) arsenates Na5ACu4(AsO4)4Cl2 (A = Rb, Cs) were synthesized by conventional solid-state methods using reactive molten salt media. These compounds are isostructural and crystallize in an orthorhombic lattice (Fmmm, No. 69; Z = 8). The cell constants are a = 14.632(3) A, b = 18.872(2) A, c = 14.445(3) A, V = 3989(1) A3, for A = Rb; a = 14.638(3) A, b = 18.990(4) A, c = 14.418(3) A, V = 4008(1) A3, for A = Cs. Single-crystal structure studies reveal a new composite framework consisting of alternating covalent and ionic lattices. The covalent lattice contains highly oriented oligomeric mu-oxo [Cu4O12]16- tetrameric units with a cyclo-S8-like Cu4O4 magnetic core that resembles the building block of layered cuprates. The ionic slab consists of a novel framework of mixed alkali metal chloride lattice and rarely seen Na6O8 clusters. Similar to organic-inorganic hybrid materials, the title compounds present a new class of host-guest chemistry via salt inclusion reactions.     

Chemistry in Molten Alkali Metal Polyselenophosphate Fluxes. Influence of Flux Composition on Dimensionality. Layers and Chains in APbPSe(4), A(4)Pb(PSe(4))(2) (A = Rb, Cs), and K(4)Eu(PSe(4))(2)

The reaction of Pb and Eu with a molten mixture of A(2)Se/P(2)Se(5)/Se produced the quaternary compounds APbPSe(4), A(4)Pb(PSe(4))(2) (A = Rb,Cs), and K(4)Eu(PSe(4))(2). The red crystals of APbPSe(4) are stable in air and water. The orange crystals of A(4)Pb(PSe(4))(2) and K(4)Eu(PSe(4))(2) disintegrate in water and over a long exposure to air. CsPbPSe(4) crystallizes in the orthorhombic space group Pnma (No. 62) with a = 18.607(4) ?, b = 7.096(4) ?, c = 6.612(4) ?, and Z = 4. Rb(4)Pb(PSe(4))(2) crystallizes in the orthorhombic space group Ibam (No. 72) with a = 19.134(9) ?, b = 9.369(3) ?, c = 10.488(3) ?, and Z = 4. The isomorphous K(4)Eu(PSe(4))(2) has a = 19.020(4) ?, b = 9.131(1) ?, c = 10.198(2) ?, and Z = 4. The APbPSe(4) have a layered structure with [PbPSe(4)](n)()(n)()(-) layers separated by A(+) ions. The coordination geometry around Pb is trigonal prismatic. The layers are composed of chains of edge sharing trigonal prisms running along the b-direction. [PSe(4)](3)(-) tetrahedra link these chains along the c-direction by sharing edges and corners with the trigonal prisms. A(4)M(PSe(4))(2) (M = Pb, Eu) has an one-dimensional structure in which [M(PSe(4))(2)](n)()(n)()(-) chains are separated by A(+) ions. The coordination geometry around M is a distorted dodecahedron. Two [PSe(4)](3)(-) ligands bridge two adjacent metal atoms, using three selenium atoms each, forming in this way a chain along the c-direction. The solid state optical absorption spectra of the compounds are reported. All compounds melt congruently in the 597-620 degrees C region.