Synthesis, structure, and bonding of A5Cd2Tl11, A = Cs, Rb. Naked pentagonal antiprismatic columns centered by cadmium

A new anionic thallium cluster chain 1 infinity[Cd2Tl11(5-)] has been discovered in the A-Cd-Tl systems for A = Cs, Rb. The compounds are synthesized by direct fusion of the elements at 700 degrees C and equilibration of the quenched product at 200 degrees C for 1 month. The thallides crystallize in the orthorhombic space group Amm2, Z = 2, a = 56107(7) and 55999(6) A, b = 18090(3) and 17603(3) A, c = 13203(3) and 12896(2) A for A = Cs and Rb, respectively, and contain chains of face-sharing pentagonal Tl10 antiprisms embedded in a matrix of alkali metal cations. Cadmium atoms occupy the center of the antiprisms and donate electrons to the anionic chain. Additional four-bonded Tl atoms on one side of the chain make the structure acentric. The compounds are diamagnetic (chi 296 = -08, -40 (x 10(-4) emu/mol, respectively) and metallic (10-20 mu omega cm at 275 K), and the indirect band gap energy of both compounds is close to zero according to extended Hückel calculations on the isolated chain.     

Na(23)K(9)Tl(15.3): An Unusual Zintl Compound Containing Apparent Tl(5)(7)(-), Tl(4)(8)(-), Tl(3)(7)(-), and Tl(5)(-) Anions

Reaction of the neat elements in tantalum containers at 400 degrees C and then 150 degrees C gives the pure title phase. X-ray crystallography shows that the hexagonal structure (P6(3)/mmc, Z = 2, a = 11.235(1) ?, b = 30.133(5) ?) contains relatively high symmetry clusters Tl(5)(7)(-) (D(3)(h)()), Tl(4)(8)(-) (C(3)(v)(), approximately T(d)), and the new Tl(3)(7)(-) (D(infinity)(h)()) plus Tl(5)(-), the last two disordered over the same elongated site in 1:2 proportions. Cation solvation of these anions is tight and specific, providing good Coulombic trapping of weakly bound electrons on the isolated cluster anions. The observed disorder makes the compound structurally a Zintl phase with a closed shell electron count. EHMO calculations on the novel Tl(3)(7)(-) reveal some bonding similarities with the isoelectronic CO(2), with two good sigma(s,p) bonding and two weakly bonding pi MO's. The Tl-Tl bond lengths therein (3.14 ?) are evidently consistent with multiple bonding. The weak temperature-independent paramagnetism and metallic conductivity (rho(293) approximately 90 &mgr;Omega.cm) of the phase are discussed.     

Synthesis and structure of the metallic K6Tl17: a layered tetrahedral star structure related to that of Cr3Si

The title compound, the Tl-richest in the K-Tl system, has been synthesized in Ta containers via direct reaction of the elements at 400 degrees C followed by quenching to room temperature and subsequent annealing at 150 degrees C for 4 weeks. It crystallizes in the orthorhombic space group Cccm (No. 66) with a = 16.625(1) A, b = 23.594(2) A, c = 15.369(2) A (22 degrees C), and Z = 8. Two different Tl(12) units consisting of augmented tetrahedral stars are condensed into layers of such tetrahedra, and further Tl(2) dumbbells and the potassium cations also interconnect the stars and layers into a three-dimensional network. The former anionic Tl(8) subunits clearly resemble those in the heteroatomic 3-D structure of cubic Cr(3)Si before their augmentation with bridging atoms. The compound is metallic (rho(270) = 22.6 micro omega x cm, alpha = 0.0023 K(-)(1)) and shows Pauli-like paramagnetic susceptibility (chi(296) = 1.1 x 10(-4) emu/mol). EHTB calculations illustrate the importance of Tl p-orbital bonding, the positive Tl-Tl overlap populations up to E(F), and greater strengths of the Tl-Tl bonding between and about the surface of the augmented Tl(12) units. Cations between the thallium layers play specific and important roles in the structure.     

K(6)Tl(2)Sb(3), a zintl phase with a novel heteroatomic (1)(infinity)[Tl4Sb(6)(12-)] chain

The title compound with heteratomic anionic chains [Tl(4)Sb(6)(12)(-)] has been discovered in the K-Tl-Sb system. The phase is obtained from a range of compositions near K(3)TlSb(1.5) following reaction first at 750-850 degrees C and then at 550 degrees C for one week or more. It crystallizes in the monoclinic system in space group C2/c, Z = 8, a = 9.951(1) A, b = 17.137(3) A, c = 19.640(6) A, and beta = 104.26(3) degrees. Swing-like (Tl(4)Sb(6))(12)(-) units consisting of alternating Sb and Tl atoms in four- and eight-membered rings are linked through Tl-Tl bonds to form infinite one-dimensional chains along a. EHTB calculations and resistivity measurements show that the compound is a semiconductor.     

Syntheses; 77Se, 203Tl, and 205Tl NMR; and theoretical studies of the Tl2Se6(6-), Tl3Se6(5-), and Tl3Se7(5-) anions and the X-ray crystal structures of [2,2,2-crypt-Na]4[Tl4Se8].en and [2,2,2-crypt-Na]2[Tl2Se4](infinity)1.en

The 2,2,2-crypt salts of the Tl4Se8(4-) and [Tl2Se4(2-)]infinity1 anions have been obtained by extraction of the ternary alloy NaTl0.5Se in ethylenediamine (en) in the presence of 2,2,2-crypt and 18-crown-6 followed by vapor-phase diffusion of THF into the en extract. The [2,2,2-crypt-Na]4[Tl4Se8].en crystallizes in the monoclinic space group P2(1)/n, with Z = 2 and a = 14.768(3) angstroms, b = 16.635(3) angstroms, c = 21.254(4) angstroms, beta = 94.17(3) degrees at -123 degrees C, and the [2,2,2-crypt-Na]2[Tl2Se4]infinity1.en crystallizes in the monoclinic space group P2(1)/c, with Z = 4 and a = 14.246(2) angstroms, b = 14.360(3) angstroms, c = 26.673(8) angstroms, beta = 99.87(3) degrees at -123 degrees C. The TlIII anions, Tl2Se6(6-) and Tl3Se7(5-), and the mixed oxidation state TlI/TlIII anion, Tl3Se6(5-), have been obtained by extraction of NaTl0.5Se and NaTlSe in en, in the presence of 2,2,2-crypt and/or in liquid NH3, and have been characterized in solution by low-temperature 77Se, 203Tl, and 205Tl NMR spectroscopy. The 1J(203,205Tl-77Se) and 2J(203,205Tl-203,205Tl) couplings of the three anions have been used to arrive at their solution structures by detailed analyses and simulations of all spin multiplets that comprise the 205,203Tl NMR subspectra arising from natural abundance 205,203Tl and 77Se isotopomer distributions. The structure of Tl2Se6(6-) is based on a Tl2Se2 ring in which each thallium is bonded to two exo-selenium atoms so that these thalliums are four-coordinate and possess a formal oxidation state of +3. The Tl4Se8(4-) anion is formally derived from the Tl2Se6(6-) anion by coordination of each pair of terminal Se atoms to the TlIII atom of a TlSe+ cation. The structure of the [Tl2Se4(2-)]infinity1 anion is comprised of edge-sharing distorted TlSe4 tetrahedra that form infinite, one-dimensional [Tl2Se42-]infinity1 chains. The structures of Tl3Se6(5-) and Tl3Se7(5-) are derived from Tl4Se4-cubes in which one thallium atom has been removed and two and three exo-selenium atoms are bonded to thallium atoms, respectively, so that each is four-coordinate and possesses a formal oxidation state of +3 with the remaining three-coordinate thallium atom in the +1 oxidation state. Quantum mechanical calculations at the MP2 level of theory show that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions exhibit true minima and display geometries that are in agreement with their experimental structures. Natural bond orbital and electron localization function analyses were utilized in describing the bonding in the present and previously published Tl/Se anions, and showed that the Tl2Se6(6-), Tl3Se6(5-), Tl3Se7(5-), and Tl4Se8(4-) anions are electron-precise rings and cages.     

First examples of thallium chalcogenide cages. Syntheses, 77Se, 203Tl, and 205Tl NMR study of the Tl4Se5(4-) and Tl4Se6(4-) anions, the X-ray crystal structure of (2,2,2-crypt-K+)3Tl5Se5(3-), and theoretical studies

The Tl5Se5(3-) anion has been obtained by extracting KTlSe in ethylenediamine in the presence of 2,2,2-crypt. The salt, (2,2,2-crypt-K+)3Tl5Se5(3-), crystallizes in the triclinic system, space group P1, with Z = 2 and a = 11.676(2) A, b = 16.017(3) A, c = 25.421(5) A, alpha = 82.42(3) degrees, beta = 88.47(3) degrees, gamma = 69.03(3) degrees at -123 degrees C. Two other mixed oxidation state TlI/TlIII anions; Tl4Se5(4-) and Tl4Se6(4-), have been obtained by extracting KTlSe into liquid NH3 in the presence of 2,2,2-crypt and have been characterized in solution by low-temperature 77Se, 203Tl, and 205Tl NMR spectroscopy and were shown to exist as a 1:1 equilibrium mixture at -40 degrees C. The couplings, 1J(203,205Tl-77Se) and 2J(203,205Tl-203,205Tl), have been observed for Tl4Se5(4-) and Tl4Se6(4-) and have been used to arrive at the solution structures of both anions. Structural assignments were achieved by detailed analyses and simulations of all spin multiplets that comprise the 205,203Tl NMR spectra and that arise from natural abundance 205,203Tl and 77Se or enriched 77Se isotopomer distributions. The structures of all three anions are based on a Tl4Se4 cube in which Tl and Se atoms occupy alternate corners. There are one and two exo-selenium atoms bonded to thallium in Tl4Se5(4-) and Tl4Se6(4-), respectively, so that these thalliums are four-coordinate and possess a formal oxidation state of +3 and the remaining three-coordinate thallium atoms are in the +1 oxidation state. The structure of Tl5Se5(3-) may be formally regarded as an adduct in which Tl+ is coordinated to the unique exo-selenium and to two seleniums in a cube face containing the TlIII atom. The Tl4Se5(4-), Tl4Se6(4-), and Tl5Se5(3-) anions and the presently unknown, but structurally related, Tl4Se4(4-) anion can be described as electron-precise cages. Ab initio methods at the MP2 level of theory show that Tl4Se5(4-), Tl4Se6(4-), and Tl5Se5(3-) exhibit true minima and display geometrical parameters that are in excellent agreement with their experimental cubanoid structures, and that Tl4Se4(4-) is cube-shaped (Td point symmetry). The gas-phase energetics associated with plausible routes to the formation and interconversions of these anions have been determined by ab initio methods and assessed. It is proposed that all three cubanoid anions are derived from the known Tl2Se2(2-), TlSe3(3-), Se2(2-), and polyselenide anions that have been shown to be present in the solutions they are derived from.     

Luminescent chains formed from neutral, triangular gold complexes sandwiching TlI and AgI. Structures of (Ag([Au(mu-C2,N3-bzim)]3)2)BF4.CH2Cl2, (Tl([Au(mu-C2,N3-bzim)]3)2)PF(6).0.5THF (bzim = 1-benzylimidazolate), and (Tl([Au(mu-C(OEt)=NC6H4CH3)]3)2)PF6.THF, with MAu6 (M = Ag+, Tl+) cluster cores

It has been found that several trinuclear complexes of AuI interact with silver and thallium salts to intercalate Ag+ and Tl+ cations, thereby forming chains. The resulting sandwich clusters center the cations between the planar trinuclear moieties producing structures in which six AuI atoms interact with each cation in a distorted trigonal prismatic coordination. The resultant (B3AB3B3AB3)infinity pattern of metal atoms also shows short (approximately 3.0 A) aurophilic interactions between BAB molecular centers. These compounds display a strong visible luminescence, under UV excitation, which is sensitive to temperature and the metal ion interacting with the gold. X-ray crystal structures are reported for Ag([Au(mu-C2,N3-bzim)]3)2BF4CH2Cl2 (P1, Z = 2, a = 14.4505(1) A; b = 15.098(2)A; c = 15.957(1)A; alpha = 106.189(3) degrees; beta = 103.551(5) degrees; gamma = 101.310(5) degrees); Tl([Au(mu-C2,N3-bzim)]3)2PF(6)05C4H8O (P1, Z = 2, a = 15.2093(1)A; b = 15.3931(4)A; c = 16.1599(4)A; alpha = 106.018(1) degrees; beta = 101.585(2) degrees; gamma = 102.068(2) degrees); and Tl([Au(mu-C(OEt)=NC6H4CH3)]3)2PF6.C4H8O (P2(1)/n, Z = 4, a = 16.4136(3)A; b = 27.6277(4)A; c = 16.7182(1)A; beta = 105.644(1) degrees). Each compound shows that the intercalated cation, Ag+ or Tl+, coordinates to a distorted trigonal prism of six AuI atoms. The counteranions reside well apart from the cations between the cluster chains.     

CsTl: A New Example of Tetragonally Compressed Tl(6)(6)(-) Octahedra. Electronic Effects and Packing Requirements in the Diverse Structures of ATl (A = Li, Na, K, Cs)

The cesium-richest phase in the Cs-Tl system, CsTl, can be isolated as a pure crystalline phase through slow cooling of cesium-richer compositions in Ta followed by vacuum sublimation of the excess Cs at approximately 100 degrees C. The compound melts incongruently in the neighborhood of 150 degrees C. The structure was established by single crystal X-ray diffraction at room temperature (orthorhombic Fddd, Z = 48, a = 32.140(3) ?, b = 15.136(1) ?, and c = 9.2400(7) ?. The isolated Tl(6)(6)(-) ions in the structure, tetragonally compressed octahedra, exhibit D(2) symmetry with 相似文献   

Characterization and ab initio XRPD structure determination of a novel silicate with Vierer single chains: the crystal structure of NaYSi2O6

The crystal structure of a sodium yttrium silicate with composition NaYSi2O6 has been determined from laboratory X-ray powder diffraction data by simulated annealing, and has been subsequently refined with the Rietveld technique. The compound is monoclinic with space group P2(1)/c and unit cell parameters of a=5.40787(2) A, b=13.69784(5) A, c=7.58431(3) A, and beta=109.9140(3) degrees at 23.5 degrees C (Z=4). The structure was found to be a single-chain silicate with a chain periodicity of four. The two symmetry dependent [Si4O12] chains in the unit cell are parallel to c. A prominent feature is the strong folding of the crankshaft-like chains within the b,c-plane resulting in intrachain Si-Si-Si angles close to 90 degrees. The coordination of the Y3+ ions by O2- is 7-fold in the form of slightly irregular pentagonal bipyramids, with oxygen atoms from four different chains contributing to the coordination polyhedron. Na+ ions are irregularly coordinated by 10 oxygens from two neighboring chains. No disorder of Na+ and Y3+ between the two nontetrahedral cation sites could be observed. Furthermore, micro-Raman spectra have been obtained from the polycrystalline material.     

Phase transition in Tl2TeO3: influence and origin of the thallium lone pair distortion

A new modification of thallium tellurite, beta-Tl(2)TeO(3), has been synthesized by methanolothermal reaction, and its phase transition has been studied by single-crystal X-ray diffraction. At a temperature of 440(10) degrees C an irreversible phase transition from a monoclinic structure (beta-Tl(2)TeO(3): P2(1)/c (No. 14), Z = 4, a = 8.9752(18) A, b = 4.8534(6) A, c = 11.884(2) A, beta = 109.67(2) degrees, V = 487.47(15) A3 at 25 degrees C) to an orthorhombic structure (alpha-Tl(2)TeO(3): Pban (No. 50), Z = 8, a = 16.646(2) A, b = 11.094(2) A, c = 5.2417(8) A, V = 968.0(3) A3 at 25 degrees C) is observed. Both structures are characterized by psi-tetrahedral TeO(3)(2-) anions. In the orthorhombic structure psi-trigonal bipyramidal [TlO(4)] units are found together with psi-tetrahedral [TlO(3)] units whereas in the monoclinic structure the coordination polyhedron around Tl(I) can be best described as a psi-square pyramide, psi-[TlO(4)]. The electronic structure of Tl(2)TeO(3) in both modifications has been studied to explain the influence of the lone pairs. It can be conclusively shown that the minimization of antibonding ns-metal/2p-oxygen interactions is the driving force for "lone pair" distortions which determines the structures of Tl(2)TeO(3).     

A detailed study of the vapochromic Behavior of [Tl[Au(C6Cl5)2]]n

The linear-chain polymer [Tl[Au(C(6)Cl(5))(2)]](n), 1, reacts in the solid state and in solution with different volatile organic compounds such as tetrahydrofuran, acetone, tetrahydrothiophene, 2-fluoropyridine, acetonitrile, acetylacetone, and pyridine. Solid-state exposure of 1 to vapors of the above VOCs produces a selective and reversible change in its color that is perceptible to the human eye and even deeper under UV irradiation, allowing 1 to function as a sensor for these VOCs. Heating the samples exposed to the VOCs for a few minutes at 100 degrees C regenerates the original material without degradation, even after several exposure/heating cycles. The reversibility is further confirmed by X-ray powder diffraction measurements of complex 1 before and after exposure to vapors and again after heating the samples. The products obtained by reactions of complex 1 with the above VOCs as ligands in solution contain extended linear chains of alternating gold and thallium centers with two molecules of the organic ligands attached to each thallium atom. The stoichiometry of these materials has been confirmed by single-crystal X-ray diffraction as [Tl(THF)(2)[Au(C(6)Cl(5))(2)]](n), 3, and [Tl(acacH)(2)[Au(C(6)Cl(5))(2)]](n), 5. Comparison of FT-IR, UV-vis, and luminescence spectra at room temperature and at 77 K of the solid samples of complexes 2-9 with the spectra of complex 1 after its exposure to VOCs suggests interaction occurs between the organic VOCs and thallium in each case. Thermogravimetric analyses data indicate that all the thallium centers in these derivatives of complex 1 are neither fully nor equally coordinatively saturated. The materials formed appear to be intermediates between complex 1 with no VOCs attached and complexes 3-9 which contain two organic ligands coordinated to each thallium. A crystal structure analyses of one of these intermediates, [Tl(THF)(0.5)[Au(C(6)Cl(5))(2)]](n), 1.0.5THF, confirms this. Density functional calculations are in accord with the observed experimental results. Analysis reveals a substantial participation of the metal atoms in transitions that give rise to the observed emissions. Crystallographic data are as follows. For 1.0.5THF: triclinic, P1, a = 8.9296(1) A, b = 11.2457(1) A, c = 21.2465(3) A, alpha = 96.7187(7) degrees, beta = 92.5886(6) degrees, gamma = 98.5911(8) degrees, V = 2090.87(4) A(3), and Z = 2. For 3: monoclinic, P2(1)/c, a = 26.4163(6) A, b = 12.1619(2) A, c = 28.0813(6) A, alpha = 90 degrees, beta = 161.9823(6) degrees, gamma = 90 degrees, V = 2790.51(10) A(3), and Z = 4. For 5: monoclinic, P2(1)/c, a = 9.8654(2) A, b = 29.8570(5) A, c = 11.6067(2) A, alpha = 90 degrees, beta = 114.5931(6) degrees, gamma = 90 degrees, V = 3108.64(10) A(3), and Z = 4.     

Polyatomic clusters of the triel elements. Palladium-centered clusters of thallium in A(8)Tl(11)Pd,A = Cs,Rb, K

Reactions of the elements within welded Ta containers at approximately 600 degrees C followed by slow cooling give new A(8)Tl(11)Pd(x) products from an apparently continuous encapsulation of Pd atoms into the pentacapped trigonal prismatic anions in the isotypic rhombohedral (R3 macro c) A(8)Tl(11) phases. All systems also produce other phases at x < 1 as well, the simplest being the cesium system in which only trigonal Pd(13)Tl(9) is also formed. Cs(8)Tl(11)Pd(0.84(1)) was characterized by single-crystal means as close to the upper x limit in that system (R3 macro c, Z = 6, a = 10.610(1) A, c = 54.683(8) A). The Pd insertion causes an expansion of the D(3) host anion, particularly about the waist, to generate a trigonal bipyramidal PdTl(5) unit (d(Pd-Tl) approximately 2.6-2.8 A) centered within a somewhat larger Tl(6) trigonal prism, the remainder of the Tl(11) cluster. Strong Tl cage bonding is retained. Extended Hückel calculations show significant involvement of all Tl 6s, 6p and Pd 4d, 5s, 5p orbital sets in the central and cage bonding. The last valence electron is considered to be delocalized in a conduction band, as in A(8)Tr(11) examples, rather than occupying an antibonding e' LUMO across a gap of approximately 2.4 eV.     

Structural studies of indium and thallium insertion into the framework of the cluster compound Ti2Nb6Cl14O4

We have investigated the possibility of altering the electronic configuration of the niobium oxochloride cluster compound Ti2Nb6Cl14O4 (I) by doping this material with monovalent cations that can fit into cavities present in its cluster framework. The doping of I with In+ and Tl+ ions resulted in the formation of MxTi2Nb6Cl14-xO4+x (M = In, x = 0.10, 0.20, 0.27; M = Tl, x = 0.10, 0.20) in which the M+ ions partially occupy these cavities. The crystal structure analysis indicated that the additional charge provided by M+ ions is compensated by substitution of chlorine by oxygen, which leads to the cluster electronic configuration being intact. Crystal data: In0.272Ti2Nb6Cl13.728O4.272, space group C2/c (No. 15), a = 12.679(2) A, b = 14.567(2) A, c = 12.632(3) A, beta = 95.26(2) degrees, Z = 4; Tl0.196Ti2Nb6Cl13.804O4.196, space group C2/c (no. 15), a = 12.732(1) A, b = 14.607(2) A, c = 12.662(2) A, beta = 95.28(1) degrees, Z = 4.     

Zr(7)Sb(4): a new binary zirconium-rich antimonide

Zr(7)Sb(4) has been prepared by arc-melting of the elemental components and annealing at 1000-1150 degrees C. Its crystal structure was determined by X-ray diffraction (Pearson symbol mP44, monoclinic, space group P2(1)/c, Z = 4, a = 8.4905(6) A, b = 11.1557(8) A, c = 11.1217(8) A, beta = 111.443(2) degrees at 295 K). Zr(7)Sb(4) is isotypic to Hf(6)TiSb(4), a compound stabilized by differential fractional site occupancy. It is the first binary group-4 antimonide with this metal-to-antimony ratio, but it differs from the corresponding phosphides and arsenides M(7)Pn(4) (M = Ti, Zr, Hf; Pn = P, As), which adopt the Nb(7)P(4)-type structure. Zr(7)Sb(4) is built up from layers excised from the tetragonal W(5)Si(3)-type structure; these layers are displaced relative to each other to maximize interlayer Zr-Zr and Zr-Sb bonding, as confirmed by band structure calculations.     

Synthesis and reactivity of the Tl1 salts of

Synthons Tl1[TCNE]*- (1) and Tl12[TCNE]2- (2), for [TCNE]*- and [TCNE]2-, respectively, in metathesis reactions have been quantitatively prepared and characterized. The structure of 1 was solved and refined in a monoclinic unit cell at 27 degrees C [C2/c, a = 12.6966 (12) angstroms, b=7.7599 (7) angstroms, c=15.5041 (15) angstroms, beta = 96.610 (5) degrees , V= 1517.4 (2) angstroms3, Dcalcd = 2.911 gcm-3, Z=8, R1 = 0.0575, omegaR2=0.0701] and exhibits nuCN absorptions at 2,191 (s) and 2,162 (s) cm-1 consistent with metal-bound [TCNE]*-. The structure of 1 consists of a distorted square antiprismatic octacoordinate Tl1 bound to six monodentate [TCNE]*-s with TlN separations ranging from 2.901 to 3.171 angstroms averaging 3.020 angstroms, and one bidentate [TCNE]*- with TlN separations averaging 3.279 angstroms. The TlN bonding is attributed to electrostatic bonding. The [TCNE]*-s form dimerized zigzag chains with intra- and interdimer separations of 2.87 and 3.29 angstroms, respectively. The tight pi-[TCNE](2)2- dimer is diamagnetic and has the shortest intradimer [TCNE]*- distance reported. These synthons for [TCNE]*- and [TCNE]2- in metathesis reactions lead to the precipitation of, for example, TlIX (X = Cl, Br, OAc). Reaction of 1 with MnIII(porphyrin)X (X = Cl, OAc) forms the molecule-based magnets of [MnIII(porphyrin)][TCNE] composition, while the reaction of [CrI(C6H6)2]Br and (Me2N)2CC(NMe2)2Cl2, [TDAE]Cl2, with 1 forms [CrI(C6H6)2] [TCNE] and [TDAE][TCNE]2, respectively. The structure of [TDAE][TCNE]2.MeCN was solved and refined in an orthorhombic unit cell at 21 degrees C [I222, a = 10.2332(15), b = 13.341(6), c = 19.907(8) angstroms, V= 2717.7 angstroms3, Z = 4; Dcalcd = 1.216 gcm-3, R=0.083, Romega = 0.104] and exhibits upsilonCN absorptions at 2,193 (m), 2,174 (s), and 2,163 (s) cm-1 consistent with isolated [TCNE](2)2- , in contrast to the aforementioned TlI bound [TCNE](2)2-. The reaction of 2 with [TDAE]Cl2 forms [TDAE]2+[TCNE]2-.     

The solid state structure of [b(10)h(11)](-) and its dynamic NMR spectra in solution

The structure of [PPh(3)(benzyl)][B(10)H(11)] was determined at -123 degrees C and 24 degrees C by single-crystal X-ray analyses. The B(10) core of [B(10)H(11)](-) is similar in shape to that of [B(10)H(10)](2)(-). The 11th H atom asymmetrically caps a polar face of the cluster and shows no tendency for disorder in the solid state. Variable temperature multinuclear NMR studies shed light on the dynamic nature of [B(10)H(11)](-) in solution. In addition to the fluxionality of the cluster H atoms, the boron cage is fluxional at moderate temperatures, in contrast to [B(10)H(10)](2)(-). Multiple exchange processes are believed to take place as a function of temperature. Results of ab initio calculations are presented. Crystal data: [PPh(3)(benzyl)][B(10)H(11)] at -123 degrees C, P2(1)/c, a = 9.988(2) A, b = 18.860(2) A, c = 15.072(2) A, beta = 107.916(8) degrees, V = 2701.5(7) A(3), Z = 4; [PPh(3)(benzyl)][B(10)H(11)] at 24 degrees C, P2(1)/c, a = 10.067(5) A, b = 19.009(9) A, c = 15.247(7) A, beta = 107.952(9) degrees, V = 2775(2) A(3), Z = 4.     

Synthesis, structure, and bonding of the nonclassical Zintl phase K5As3Pb3

The title phase was synthesized by direct fusion of a stoichiometric amount of the elements followed by annealing at 650 degrees C for 3 weeks. The compound crystallizes in the orthorhombic space group Pnma (No. 62), Z = 4, with a = 19.451(6) A, b = 12.164(3) A, c = 6.581(1) A. The compound is made up of As(3)Pb(3)(5-) crown clusters that can be likened geometrically and electronically to 6-atom hypho-clusters derived from a tricapped trigonal prismatic closo parent. These crowns are interconnected via intercluster Pb-Pb bonds to form infinite chains along the b axis, which means the compound contains an extra two cations and two electrons per formula unit. Extended Hückel calculations indicate that the two additional electrons per cluster are accommodated in pi states on the cluster and predict that the phase should be semiconducting. The latter is confirmed by microwave resistivity measurements, rho(298) = 1.0 x 10(2) microOmega.cm; (deltarho/deltaT)/rho = -0.14(3) K(-)(1).     

Synthesis, structure, and theoretical study of the nonclassical [CuTe(7)](3-) anion

The compound [PPh(4)](2)[NEt(4)][CuTe(7)] has been synthesized from the reaction of CuCl with a polytelluride solution in dimethylformamide at room temperature. The compound crystallizes with two formula units in the triclinic space group P(-)1 in a cell with dimensions a = 8.9507(18) A, b = 14.714(3) A, and c = 23.277(5) A and alpha= 86.32(3) degrees, beta= 80.17(3) degrees, and gamma= 75.63(3) degrees (T = -120 degrees C). Ab initio calculations indicate that the nonclassical [CuTe(7)](3)(-) anion is the result of joining Te(3)(2-) and [CuTe(4)](1-) fragments through donor-acceptor interactions.     

Heteroatomic Centering of Icosahedral Clusters. Crystal and Electronic Structure of the K(6)(NaCd)(2)Tl(12)Cd Compound Containing the Not-So-Naked Tl(12)Cd(12-) Polyanion

The title compound was synthesized in a niobium container by fusion of the elements followed by slow cooling. In the first stage, the stoichiometric proportion KNaCd(3)Tl(7) yielded a heterogeneous product containing a few single crystals of the compound K(6)(Na(2.36(9))Cd(1.64(9)))Tl(12)Cd, the structure of which was established by a single crystal X-ray diffraction technique (cubic, Im&thremacr;, a = 11.352(2) ?, Z = 2, R(F) = 3.24%, Rw(F) = 4.60%). Occurrence of a stoichiometry range for the compound was indicated after a new reaction starting from the composition K(6)Na(2)Cd(3)Tl(12) gave a quite homogeneous and well-crystallized product (refined composition K(6)(Na(1.93(7))Cd(2.07(7)))Tl(12)Cd, Im&thremacr;, a = 11.321(2) ?, Z = 2, R(F) = 3.98%, Rw(F) = 4.99%). The structure of K(6)(NaCd)(2)Tl(12)Cd is distinguishable from that reported for Na(4)K(6)Tl(13) by replacement of the icosahedron centering thallium and of half the sodium cations by cadmium. Statistical occupation disorder occurs on the 8(c) position of the outer Cd/Na atom. The structure contains the 50-electron closed shell centered Tl(12)Cd(12-) icosahedral cluster with &thremacr;m symmetry (T(h)). Extended Hückel molecular orbital and band calculations were carried out to analyze the centering effect on the anion stability and look at the electron transfer, especially from cadmium lying within the first coordination shell of the icosahedral cluster. Electron localization within the Cd-centered icosahedron is not as evident as in the Tl-centered thallium icosahedral clusters described elsewhere; actually, cadmium is found to bridge icosahedra within a more three-dimensional network than sodium by forming bonds that are mainly covalent. The compound is a semiconducting Zintl phase with closed shell bonding.     

New Heptafluorozirconates and ‐hafnates AIBIIZr(Hf)F7 (AI = Rb,Tl; BII = Ca,Cd) – Synthesis,Structures, and Structural Relationships

Four new ABZrF₇ heptafluorozirconates (A = Rb, Tl; B = Ca, Cd) and their homologous heptafluorohafnates, all colorless, orthorhombic Cmcm (n^o63), Z = 4, have been synthesized by heating stoichiometric mixtures of RbF or TlF, CaF₂ or CdF₂ and ZrF₄ (HfF₄) in sealed platinum tubes at temperature ranging from 550 °C (Tl) to 600 °C (Rb). The crystal structures of both RbCdZrF₇ and TlCdZrF₇ have been solved from single‐crystal X‐rays diffraction data. Rietveld refinements were performed from X‐rays powder patterns for RbCaZrF₇ and TlCaZrF₇. In this series of heptafluorides, both B²⁺ and Zr⁴⁺ cations exhibit a pentagonal bipyramidal 7‐coordination. Their structural relationships with other heptafluorozirconates A^IB^IIZrF₇ as well as β‐KYb₂F₇ are discussed. RbCaZrF₇: a = 6.863(1) Å, b = 11.130(1) Å, c = 8.485(1) Å; TlCaZrF₇: a = 6.868(1) Å, b = 11.165(1) Å, c = 8.486(1) Å; RbCdZrF₇: a = 6.780(1) Å, b = 11.054(4) Å, c = 8.420(4) Å; TlCdZrF₇: a = 6.784(3) Å, b = 11.099(2) Å, c = 8.424(9) Å.