Diverse evolution of [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 2, 3) metalloligands in CH(2)Cl(2)

The nucleophilicity of the [Pt(2)S(2)] core in [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 3, dppp (1); n = 2, dppe (2)) metalloligands toward the CH(2)Cl(2) solvent has been thoroughly studied. Complex 1, which has been obtained and characterized by X-ray diffraction, is structurally related to 2 and consists of dinuclear molecules with a hinged [Pt(2)S(2)] central ring. The reaction of 1 and 2 with CH(2)Cl(2) has been followed by means of (31)P, (1)H, and (13)C NMR, electrospray ionization mass spectrometry, and X-ray data. Although both reactions proceed at different rates, the first steps are common and lead to a mixture of the corresponding mononuclear complexes [Pt[Ph(2)P(CH(2))(n)PPh(2)](S(2)CH(2))], n = 3 (7), 2 (8), and [Pt[Ph(2)P(CH(2))(n)PPh(2)]Cl(2)], n = 3 (9), 2 (10). Theoretical calculations give support to the proposed pathway for the disintegration process of the [Pt(2)S(2)] ring. Only in the case of 1, the reaction proceeds further yielding [Pt(2)(dppp)(2)[mu-(SCH(2)SCH(2)S)-S,S']]Cl(2) (11). To confirm the sequence of the reactions leading from 1 and 2 to the final products 9 and 11 or 8 and 10, respectively, complexes 7, 8, and 11 have been synthesized and structurally characterized. Additional experiments have allowed elucidation of the reaction mechanism involved from 7 to 11, and thus, the origin of the CH(2) groups that participate in the expansion of the (SCH(2)S)(2-) ligand in 7 to afford the bridging (SCH(2)SCH(2)S)(2-) ligand in 11 has been established. The X-ray structure of 11 is totally unprecedented and consists of a hinged [(dppp)Pt(mu-S)(2)Pt(dppp)] core capped by a CH(2)SCH(2) fragment.     

Transformation of organic molecules on the low-valent [M(Ph(2)PCH(2)CH(2)PPh(2))(2)] moiety derived from trans-[M(N(2))(2)(Ph(2)PCH(2)CH(2)PPh(2))(2)] or related complexes (M = Mo, W)

A zero-valent [M(Ph(2)PCH(2)CH(2)PPh(2))(2)] moiety (M = Mo, W) generated in situ by dissociation of the N(2) ligands in trans-[M(N(2))(2)(Ph(2)PCH(2)CH(2)PPh(2))(2)] can activate pi-accepting organic molecules including isocyanides and nitriles, which undergo the electrophilic attack caused by a strong pi-donation from a zero-valent metal center. Cleavage of a variety of C-X bonds (X = H, C, N, O, P, halogen) also occurs at their electron-rich sites through oxidative addition to form reactive intermediates, which subsequently degradate to yield smaller molecules either bound to or dissociated from the metal center. The mechanism is substantiated unambiguously by isolation of numerous intermediate stages.     

New layered materials: syntheses, structures, and optical properties of K(2)TiCu(2)S(4), Rb(2)TiCu(2)S(4), Rb(2)TiaAg(2)S(4), Cs(2)TiAg(2)sS(4), and Cs(2)TiCu(2)Se(4)

The new compounds K(2)TiCu(2)S(4), Rb(2)TiCu(2)S(4), Rb(2)TiAg(2)S(4), Cs(2)TiAg(2)S(4), and Cs(2)TiCu(2)Se(4) have been synthesized by the reactions of A(2)Q(3) (A = K, Rb, Cs; Q = S, Se) with Ti, M (M = Cu or Ag), and Q at 823 K. The compounds Rb(2)TiCu(2)S(4), Cs(2)TiAg(2)S(4), and Cs(2)TiCu(2)Se(4) are isostructural. They crystallize with two formula units in space group P4(2)/mcm of the tetragonal system in cells of dimensions a = 5.6046(4) A, c = 13.154(1) A for Rb(2)TiCu(2)S(4), a =6.024(1) A, c = 13.566(4) A for Cs(2)TiAg(2)S(4), and a =5.852(2) A, c =14.234(5) A for Cs(2)TiCu(2)Se(4) at 153 K. Their structure is closely related to that of Cs(2)ZrAg(2)Te(4) and comprises [TiM(2)Q(4)(2)(-)] layers, which are separated by alkali metal atoms. The [TiM(2)Q(4)(2)(-)] layer is anti-fluorite-like with both Ti and M atoms tetrahedrally coordinated to Q atoms. Tetrahedral coordination of Ti(4+) is rare in the solid state. On the basis of unit cell and space group determinations, the compounds K(2)TiCu(2)S(4) and Rb(2)TiAg(2)S(4) are isostructural with the above compounds. The band gaps of K(2)TiCu(2)S(4), Rb(2)TiCu(2)S(4), Rb(2)TiAg(2)S(4), and Cs(2)TiAg(2)S(4) are 2.04, 2.19, 2.33, and 2.44 eV, respectively, as derived from optical measurements. From band-structure calculations, the optical absorption for an A(2)TiM(2)Q(4) compound is assigned to a transition from an M d and Q p valence band (HOMO) to a Ti 3d conduction band.     

Synthesis, Spectroscopic Characterization, and Structural Studies of Bis(&mgr;-sulfido)bis[{O,O-dialkyl (alkylene) dithiophosphato}oxomolybdenum(V)] Complexes. Crystal Structures of Mo(2)O(2)S(2)[S(2)P(OEt)(2)](2), Mo(2)O(2)S(2)[S(2)P(OEt)(2)](2).2NC(5)H(5), and Mo(2)O(3)[S(2)P(OPh)(2)](4)

A series of new complexes, Mo(2)O(2)S(2)[S(2)P(OR)(2)](2) (where R = Et, n-Pr, i-Pr) and Mo(2)O(2)S(2)[S(2)POGO](2) (where G = -CH(2)CMe(2)CH(2)-, -CMe(2)CMe(2)-) have been prepared by the dropwise addition of an ethanolic solution of the ammonium or sodium salt of the appropriate O,O-dialkyl or -alkylene dithiophosphoric acid, or the acid itself, to a hot aqueous solution of molybdenum(V) pentachloride. The complexes were also formed by heating solutions of Mo(2)O(3)[S(2)P(OR)(2)](4) or Mo(2)O(3)[S(2)POGO](4) species in glacial acetic acid. The Mo(2)O(2)S(2)[S(2)P(OR)(2)](2) and Mo(2)O(2)S(2)[S(2)POGO](2) compounds were characterized by elemental analyses, (1)H, (13)C, and (31)P NMR, and infrared and Raman spectroscopy, as were the 1:2 adducts formed on reaction with pyridine. The crystal structures of Mo(2)O(2)S(2)[S(2)P(OEt(2))](2), Mo(2)O(2)S(2)[S(2)P(OEt)(2)](2).2NC(5)H(5), and Mo(2)O(3)[S(2)P(OPh)(2)](4) were determined. Mo(2)O(2)S(2)[S(2)P(OEt)(2)](2) (1) crystallizes in space group C2/c, No. 15, with cell parameters a = 15.644(3) ?, b = 8.339(2) ?, c = 18.269(4) ?, beta = 103.70(2) degrees, V = 2315.4(8) ?(3), Z = 4, R = 0.0439, and R(w) = 0.0353. Mo(2)O(2)S(2)[S(2)P(OEt)(2)](2).2NC(5)H(5) (6) crystallizes in space group P&onemacr;, No. 2, with the cell parameters a = 12.663(4) ?,b = 14.291(5) ?, c = 9.349(3) ?, alpha = 100.04(3) degrees, beta = 100.67(3) degrees, gamma = 73.03(3) degrees V = 1557(1) ?(3), Z = 2, R = 0.0593, and R(w) = 0.0535. Mo(2)O(3)[S(2)P(OPh)(2)](4) (8) crystallizes in space group P2(1)/n, No. 14, with cell parameters a = 15.206(2)?, b = 10.655(3)?, c = 19.406(3)?, beta = 111.67(1) degrees, V = 2921(1)?(3), Z = 2, R = 0.0518, R(w) = 0.0425. The immediate environment about the molybdenum atoms in 1 is essentially square pyramidal if the Mo-Mo interaction is ignored. The vacant positions in the square pyramids are occupied by two pyridine molecules in 6, resulting in an octahedral environment with very long Mo-N bonds. The terminal oxygen atoms in both 1 and 6 are in the syn conformation. In 8, which also has a distorted octahedral environment about molybdenum, two of the dithiophosphate groups are bidentate as in 1 and 6, but the two others have one normal Mo-S bond and one unusually long Mo-S bond.     

Synthesis and Structural Characterization of Cu（pic）2[CO（NH2）2]2 and （picH2）2[Cu（pic）2（SCN）2]

1 INTRODUCTION The picolinic acid (picH), also called pyridine- 2-carboxylic acid, has a broad spectrum of physio- logical effects on the activity functions of both ani- mal and plant organisms. It is attributed increasing interest due to its ability to …     

Double silyl migration converting ORe[N(SiMe(2)CH(2)PCy(2))(2)] to NRe[O(SiMe(2)CH(2)PCy(2))(2)] substructures

The reaction of (R(2)PCH(2)SiMe(2))(2)NM (PNP(R)M; R = Cy; M = Li, Na, MgHal, Ag) with L(2)ReOX(3) [L(2) = (Ph(3)P)(2) or (Ph(3)PO)(Me(2)S); X = Cl, Br] gives (PNP(Cy))ReOX(2) as two isomers, mer,trans and mer,cis. These compounds undergo a double Si migration from N to O at 90 degrees C to form (POP(Cy))ReNX(2) as a mixture of mer,trans and fac,cis isomers. Additional thermolysis effects migration of CH(3) from Si to Re, along with compensating migration of halide from Re to Si. DFT calculations on various structural isomers support the greater thermodynamic stability of the POP/ReN isomer vs PNP/ReO and highlight the influence of the template effect on the reactivities of these species.     

Expanding the remarkable structural diversity of uranyl tellurites: hydrothermal preparation and structures of K[UO(2)Te(2)O(5)(OH)], Tl(3)[(UO(2))(2)[Te(2)O(5)(OH)](Te(2)O(6))].2H(2)O,beta-Tl(2)[UO(2)(TeO(3))(2)], and Sr(3)[UO(2)(TeO(3))(2)](TeO(3))(2)

The reactions of UO(2)(C(2)H(3)O(2))(2).2H(2)O with K(2)TeO(3).H(2)O, Na(2)TeO(3) and TlCl, or Na(2)TeO(3) and Sr(OH)(2).8H(2)O under mild hydrothermal conditions yield K[UO(2)Te(2)O(5)(OH)] (1), Tl(3)[(UO(2))(2)[Te(2)O(5)(OH)](Te(2)O(6))].2H(2)O (2) and beta-Tl(2)[UO(2)(TeO(3))(2)] (3), or Sr(3)[UO(2)(TeO(3))(2)](TeO(3))(2) (4), respectively. The structure of 1 consists of tetragonal bipyramidal U(VI) centers that are bound by terminal oxo groups and tellurite anions. These UO(6) units span between one-dimensional chains of corner-sharing, square pyramidal TeO(4) polyhedra to create two-dimensional layers. Alternating corner-shared oxygen atoms in the tellurium oxide chains are protonated to create short/long bonding patterns. The one-dimensional chains of corner-sharing TeO(4) units found in 1 are also present in 2. However, in 2 there are two distinct chains present, one where alternating corner-shared oxygen atoms are protonated, and one where the chains are unprotonated. The uranyl moieties in 2 are bound by five oxygen atoms from the tellurite chains to create seven-coordinate pentagonal bipyramidal U(VI). The structures of 3 and 4 both contain one-dimensional [UO(2)(TeO(3))(2)](2-) chains constructed from tetragonal bipyramidal U(VI) centers that are bridged by tellurite anions. The chains differ between 3 and 4 in that all of the pyramidal tellurite anions in 3 have the same orientation, whereas the tellurite anions in 4 have opposite orientations on each side of the chain. In 4, there are also additional isolated TeO(3)(2-) anions present. Crystallographic data: 1, orthorhombic, space group Cmcm, a = 7.9993(5) A, b = 8.7416(6) A, c = 11.4413(8) A, Z = 4; 2, orthorhombic, space group Pbam, a = 10.0623(8) A, b = 23.024(2) A, c = 7.9389(6) A, Z = 4; 3, monoclinic, space group P2(1)/n, a = 5.4766(4) A, b = 8.2348(6) A, c = 20.849(3) A, beta = 92.329(1) degrees, Z = 4; 4, monoclinic, space group C2/c, a = 20.546(1) A, b = 5.6571(3) A, c = 13.0979(8) A, beta = 94.416(1) degrees, Z = 4.     

Rhodium-catalyzed dehydrocoupling of the sterically encumbered phosphine-borane adduct tBu(2)PH.BH(3): synthesis of the linear dimers tBu(2)PH-BH(2)-tBu(2)P-BH(3) and tBu(2)PH-BH(2)-tBu(2)P-BH(2)Cl

The dehydrocoupling of the sterically hindered phosphine-borane adduct tBu(2)PH.BH(3) above 140 degrees C is catalyzed by the rhodium complexes [Rh(1,5-cod)(2)][OTf] or Rh(6)(CO)(16) to give the four-membered chain tBu(2)PH-BH(2)-tBu(2)P-BH(3) (1), which was isolated in 60% yield and characterized by multinuclear NMR spectroscopy, mass spectrometry, and elemental analysis. Thermolysis of 1 in the temperature range 175-180 degrees C led to partial decomposition and the formation of tBu(2)PH.BH(3). When the dehydrocoupling of tBu(2)PH.BH(3) was performed in the presence of [[Rh(mu-Cl)(1,5-cod)](2)] or RhCl(3) hydrate, the chlorinated compound tBu(2)PH-BH(2)-tBu(2)P-BH(2)Cl (2) was formed which could not be obtained free of 1. The molecular structures of tBu(2)PH.BH(3), tBu(2)PH-BH(2)-tBu(2)P-BH(3) (1), and tBu(2)PH-BH(2)-tBu(2)P-BH(2)Cl (2) together with 1 were determined by single-crystal X-ray diffraction studies.     

Excision of uranium oxide chains and ribbons in the novel one-dimensional uranyl iodates K(2)[(UO(2))3(IO(3))(4)O(2)] and Ba[(UO(2)2(IO(3))(2)O(2)](H(2)O)

The alkali metal and alkaline-earth metal uranyl iodates K(2)[(UO(2))(3)(IO(3))(4)O(2)] and Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) have been prepared from the hydrothermal reactions of KCl or BaCl(2) with UO(3) and I(2)O(5) at 425 and 180 degrees C, respectively. While K(2)[(UO(2))(3)(IO(3))(4)O(2)] can be synthesized under both mild and supercritical conditions, the yield increases from <5% to 73% as the temperature is raised from 180 to 425 degrees C. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), however, has only been isolated from reactions performed in the mild temperature regime. Thermal measurements (DSC) indicate that K(2)[(UO(2))(3)(IO(3))(4)O(2)] is more stable than Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) and that both compounds decompose through thermal disproportionation at 579 and 575 degrees C, respectively. The difference in the thermal behavior of these compounds provides a basis for the divergence of their preparation temperatures. The structure of K(2)[(UO(2))(3)(IO(3))(4)O(2)] is composed of [(UO(2))(3)(IO(3))(4)O(2)](2)(-) chains built from the edge-sharing UO(7) pentagonal bipyramids and UO(6) octahedra. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) consists of one-dimensional [(UO(2))(2)(IO(3))(2)O(2)](2)(-) ribbons formed from the edge sharing of distorted UO(7) pentagonal bipyramids. In both compounds the iodate groups occur in both bridging and monodentate binding modes and further serve to terminate the edges of the uranium oxide chains. The K(+) or Ba(2+) cations separate the chains or ribbons in these compounds forming bonds with terminal oxygen atoms from the iodate ligands. Crystallographic data: K(2)[(UO(2))(3)(IO(3))(4)O(2)], triclinic, space group P_1, a = 7.0372(5) A, b = 7.7727(5) A, c = 8.9851(6) A, alpha = 93.386(1) degrees, beta = 105.668(1) degrees, gamma = 91.339(1) degrees, Z = 1; Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), monoclinic, space group P2(1)/c, a = 8.062(4) A, b = 6.940(3) A, c = 21.67(1), beta= 98.05(1) degrees, Z = 4.     

Gold(I) Complexes with the nido-Diphosphino Ligand [7,8-(Ph(2)P)(2)-7,8-C(2)B(9)H(10)](-). Preparation of the First Metallocarborane Complex of this Ligand. Crystal Structures of [Au{(PPh(2))(2)C(2)B(9)H(10)}(PPh(3))].CH(2)Cl(2) and [Au(2){(PPh(2))(2)C(2)B(9)H(10)}(2){(PPh(2))(2)(CH(2))(3)}].3Me(2)CO

The reaction of [AuCl(PR(3))] with [1,2-(Ph(2)P)(2)-1,2-C(2)B(10)H(10)] in refluxing ethanol proceeds with partial degradation (removal of a boron atom adjacent to carbon) of the closo species to give [Au{(PPh(2))(2)C(2)B(9)H(10)}(PR(3))] [PR(3) = PPh(3) (1), PPh(2)Me (2), PPh(2)(4-Me-C(6)H(4)) (3), P(4-Me-C(6)H(4))(3) (4), P(4-OMe-C(6)H(4))(3) (5)]. Similarly, the treatment of [Au(2)Cl(2)(&mgr;-P-P)] with [1,2-(Ph(2)P)(2)-1,2-C(2)B(10)H(10)] under the same conditions leads to the complexes [Au(2){(PPh(2))(2)C(2)B(9)H(10)}(2)(&mgr;-P-P)] [P-P = dppe = 1,2-bis(diphenylphosphino)ethane (6), dppp = 1,3-bis(diphenylphosphino)propane (7)], where the dppe or dppp ligands bridge two gold nido-diphosphine units. The reaction of 1 with NaH leads to removal of one proton, and further reaction with [Au(PPh(3))(tht)]ClO(4) gives the novel metallocarborane compound [Au(2){(PPh(2))(2)C(2)B(9)H(9)}(PPh(3))(2)] (8). The structure of complexes 1 and 7 have been established by X-ray diffraction. [Au{(PPh(2))(2)C(2)B(9)H(10)}(PPh(3))] (1) (dichloromethane solvate) crystallizes in the monoclinic space group P2(1)/c, with a = 17.326(3) ?, b = 20.688(3) ?, c = 13.442(2) ?, beta = 104.710(12) degrees, Z = 4, and T = -100 degrees C. [Au(2){(PPh(2))(2)C(2)B(9)H(10)}(2)(&mgr;-dppp)] (7) (acetone solvate) is triclinic, space group P&onemacr;, a = 13.432(3) ?, b = 18.888(3) ?, c = 20.021(3) ?, alpha = 78.56(2) degrees, beta = 72.02(2) degrees, gamma = 73.31(2) degrees, Z = 2, and T = -100 degrees C. In both complexes the gold atom exhibits trigonal planar geometry with the 7,8-bis(diphenylphosphino)-7,8-dicarba-nido-undecaborate(1-) acting as a chelating ligand.     

Structural characterization of nanosized CeO(2)-SiO(2), CeO(2)-TiO(2), and CeO(2)-ZrO(2) catalysts by XRD, Raman, and HREM techniques

Structural characteristics of nanosized ceria-silica, ceria-titania, and ceria-zirconia mixed oxide catalysts have been investigated using X-ray diffraction (XRD), Raman spectroscopy, BET surface area, thermogravimetry, and high-resolution transmission electron microscopy (HREM). The effect of support oxides on the crystal modification of ceria cubic lattice was mainly focused. The investigated oxides were obtained by soft chemical routes with ultrahighly dilute solutions and were subjected to thermal treatments from 773 to 1073 K. The XRD results suggest that the CeO(2)-SiO(2) sample primarily consists of nanocrystalline CeO(2) on the amorphous SiO(2) surface. Both crystalline CeO(2) and TiO(2) anatase phases were noted in the case of CeO(2)-TiO(2) sample. Formation of cubic Ce(0.75)Zr(0.25)O(2) and Ce(0.6)Zr(0.4)O(2) (at 1073 K) were observed in the case of the CeO(2)-ZrO(2) sample. Raman measurements disclose the fluorite structure of ceria and the presence of oxygen vacancies/Ce(3+). The HREM results reveal well-dispersed CeO(2) nanocrystals over the amorphous SiO(2) matrix in the cases of CeO(2)-SiO(2), isolated CeO(2), and TiO(2) (anatase) nanocrystals, some overlapping regions in the case of CeO(2)-TiO(2), and nanosized CeO(2) and Ce-Zr oxides in the case of CeO(2)-ZrO(2) sample. The exact structural features of these crystals as determined by digital diffraction analysis of HREM experimental images reveal that the CeO(2) is mainly in cubic fluorite geometry. The oxygen storage capacity (OSC) as determined by thermogravimetry reveals that the OSC of the mixed oxide systems is more than that of pure CeO(2) and is system dependent.     

The 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) states of the SO(2) (+) ion studied using multiconfiguration second-order perturbation theory

The 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) electronic states of the SO(2) (+) ion have been studied using multiconfiguration second-order perturbation theory (CASPT2) and two contracted atomic natural orbital basis sets, S[6s4p3d1f]/O[5s3p2d1f] (ANO-L) and S[4s3p2d]/O[3s2p1d] (ANO-S), and the three states were considered to correspond to the observed X, B, and A states, respectively, in the previous experimental and theoretical studies. Based on the CASPT2/ANO-L adiabatic excitation energy calculations, the X, A, and B states of SO(2) (+) are assigned to 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2), respectively, and our assignments of the A and B states are contrary to the previous assignments (A to (2)A(2) and B to (2)B(2)). The CASPT2/ANO-L energetic calculations also indicate that the 1 (2)A(1), 1 (2)B(2), and 1 (2)A(2) states are, respectively, the ground, first excited, and second excited states at the ground-state (1 (2)A(1)) geometry of the ion and at the geometry of the ground-state SO(2) molecule. Based on the CASPT2/ANO-L results for the geometries, we realize that the experimental geometries (determined by assuming the bond lengths to be the same as the neutral ground state of SO(2)) were not accurate. The CASPT2/ANO-S calculations for the potential energy curves as functions of the OSO angle confirm that the 1 (2)B(2) and 1 (2)A(2) states are the results of the Renner-Teller effect in the degenerate (2)Pi(g) state at the linear geometry, and it is clearly shown that the 1 (2)B(2) curve, as the lower component of the Renner splitting, lies below the 1 (2)A(2) curve. The UB3LYP/cc-pVTZ adiabatic excitation energy calculations support the assignments (A to (2)B(2) and B to (2)A(2)) based on the CASPT2/ANO-L calculations.     

Transition metal containing decatungstosilicate dimer [M(H(2)O)(2)(gamma-SiW(10)O(35))(2)](10-) (M = Mn(2+), Co(2+), Ni(2+))

The new, monometal substituted silicotungstates [Mn(H(2)O)(2)(gamma-SiW(10)O(35))(2)](10-) (1), [Co(H(2)O)(2)(gamma-SiW(10)O(35))(2)](10-) (2) and [Ni(H(2)O)(2)(gamma-SiW(10)O(35))(2)](10-) (3) have been synthesized and isolated as the potassium salts K(10)[Mn(H(2)O)(2)(gamma-SiW(10)O(35))(2)] x 8.25 H(2)O (K-1), K(10)[Co(H(2)O0(2)(gamma-SiW(10)O(35))(2)] x 8.25 H(2)O (K-2) and K(10)[Ni(H(2)O)(2)(gamma-SiW(10)O(35))(2)] x 13.5 H(2)O (K-3), which have been characterized by IR spectroscopy, single crystal X-ray diffraction, elemental analysis and cyclic voltammetry. Polyanions 1-3 are composed of two (gamma-SiW(10)O(36)) units fused on one side via two W-O-W' bridges and on the other side by an octahedrally coordinated trans-MO(4)(OH(2))(2) transition metal fragment, resulting in a structure with C(2v) point group symmetry. Anions 1-3 were synthesized by reaction of the dilacunary precursor [gamma-SiW(10)O(36)](8-) with Mn(2+), Co(2+) and Ni(2+) ions, respectively, in 1 M KCl solution at pH 4.5. The electrochemical properties of 1-3 were studied by cyclic voltammetry and controlled potential coulometry in a pH 5 buffer medium. The waves associated with the W-centers are compared with each other and with those of the parent lacunary precursor [gamma-SiW(10)O(36)](8-) in the same medium. They appear to be dominated by the acid-base properties of the intermediate reduced species. A facile merging of the waves for 3 is observed while those for 1 and 2 remain split. Controlled potential coulometry of the single wave of 3 or the combined waves of 1 and 2 is accompanied by catalysis of the hydrogen evolution reaction. No redox activity was detected for the Ni(2+) center in 3, whereas the Co(2+) center in 2 shows a one-electron redox process. The two-electron, chemically reversible process of the Mn(2+) center in 1 is accompanied by a film deposition on the electrode surface.     

Infinite Three-Dimensional Coordination Polymers: Synthesis and Structures of [Cd (4,4'-bpy)2 (H2O)2]n (pic)2n, [Zn (4,4'-bpy)2 (H2O)2 ]n-(pic)2n (H2O)2n, and [Zn (4,4'-bpy)2 (H2O)2]n (4,4'-bpy)n (H2O)n (pic)2n

Recently, a new research realm in crystal engineering of supramolecular architecturesassembled by means of coordinate covalent bonding', hydrogen bonding', or other weakintermolecular interactions= has been rapidly expanding in order to rationally developnew classes of functional materials with cavities or pores. These types of compoundsmay exhibit interesting topological structures and the clathrations of the cavity structuresmay have many potential properties such as catalysis', electrical co…     

Polydentate N(2)S(2)O and N(2)S(2)O(2) Ligands as Alcoholic Derivatives of (N,N'-Bis(2-mercaptoethyl)-1,5-diazacyclooctane)nickel(II) and (N,N'-Bis(2-mercapto-2-methylpropane)-1,5-diazacyclooctane)nickel(II)

The synthesis, structural characterization, spectroscopic, and electrochemical properties of N(2)S(2)-ligated Ni(II) complexes, (N,N'-bis(2-mercaptoethyl)-1,5-diazacyclooctane)nickel(II), (bme-daco)Ni(II), and (N,N'-bis(2-mercapto-2-methylpropane)1,5-diazacyclooctane)nickel(II), (bme-daco)Ni(II), derivatized at S with alcohol-containing alkyl functionalities, are described. Reaction of (bme-daco)Ni(II) with 2-iodoethanol afforded isomers, (N,N'-bis(5-hydroxy-3-thiapentyl)-1,5-diazacyclooctane-O,N,N',S,S')halonickel(II) iodide (halo = chloro or iodo), 1, and (N,N'-bis(5-hydroxy-3-thiapentyl)-1,5-diazacyclooctane-N,N',S,S')nickel(II) iodide, 2, which differ in the utilization of binding sites in a potentially hexadentate N(2)S(2)O(2) ligand. Blue complex 1 contains nickel in an octahedral environment of N(2)S(2)OX donors; X is best modeled as Cl. It crystallizes in the monoclinic space group P2(1)/n with a = 12.580(6) ?, b = 12.291(6) ?, c = 13.090(7) ?, beta = 97.36(4) degrees, and Z = 4. In contrast, red complex 2 binds only the N(2)S(2) donor set forming a square planar nickel complex, leaving both -CH(2)CH(2)OH arms dangling; the iodide ions serve strictly as counterions. 2 crystallizes in the orthorhombic space group Pca2(1) with a = 15.822(2) ?, b = 13.171(2) ?, c = 10.0390(10) ?, and Z = 4. Reaction of (bme-daco)Ni(II) with 1,3-dibromo-2-propanol affords another octahedral Ni species with a N(2)S(2)OBr donor set, ((5-hydroxy-3,7-dithianonadiyl)-1,5-diazacyclooctane-O,N,N',S,S')bromonickel(II) bromide, 3. Complex 3 crystallizes in the orthorhombic space group Pca2(1) with a = 15.202(5) ?, b = 7.735(2) ?, c = 15.443(4) ?, and Z = 4. Complex 4.2CH(3)CN was synthesized from the reaction of (bme-daco)Ni(II) with 1,3-dibromo-2-propanol. It crystallizes in the monoclinic space group P2/c with a = 20.348(5) ?, b = 6.5120(1) ?, c = 20.548(5) ?, and Z = 4.     

Gas-phase coordination complexes of U(VI)O2(2+), Np(VI)O2(2+), and Pu(VI)O2(2+) with dimethylformamide

Electrospray ionization of actinyl perchlorate solutions in H₂O with 5% by volume of dimethylformamide (DMF) produced the isolatable gas-phase complexes, [An^VIO₂(DMF)₃(H₂O)]²⁺ and [An^VIO₂(DMF)₄]²⁺, where An = U, Np, and Pu. Collision-induced dissociation confirmed the composition of the dipositive coordination complexes, and produced doubly- and singly-charged fragment ions. The fragmentation products reveal differences in underlying chemistries of uranyl, neptunyl, and plutonyl, including the lower stability of Np(VI) and Pu(VI) compared with U(VI).     

Reaction of [P(2)N(2)]Ta==CH(2)(Me) with ethylene: synthesis of [P(2)N(2)]Ta(C(2)H(4))Et, a neutral species with a beta-agostic ethyl group in equilibrium with an alpha-agostic ethyl group ([P(2)N(2)] = PhP(CH(2)SiMe(2)CH(2))(2)PPh).

The photolysis of [P(2)N(2)]TaMe(3) ([P(2)N(2)] = PhP(CH(2)SiMe(2)NSiMe(2)CH(2))(2)PPh) produces [P(2)N(2)]Ta=CH(2)(Me) as the major product. The thermally unstable methylidene complex decomposes in solution in the absence of trapping agents to unidentified products. However, in the presence of ethylene [P(2)N(2)]Ta=CH(2)(Me) is slowly converted to [P(2)N(2)]Ta(C(2)H(4))Et, with [P(2)N(2)]Ta(C(2)H(4))Me observed as a minor product. A mechanistic study suggests that the formation of [P(2)N(2)]Ta(C(2)H(4))Et results from the trapping of [P(2)N(2)]TaEt, formed by the migratory insertion of the methylene moiety into the tantalum-methyl bond. The minor product, [P(2)N(2)]Ta(C(2)H(4))Me, forms from the decomposition of a tantalacyclobutane resulting from the addition of ethylene to [P(2)N(2)]Ta=CH(2)(Me) and is accompanied by the production of an equivalent of propylene. Pure [P(2)N(2)]Ta(C(2)H(4))Et can be synthesized by hydrogenation of [P(2)N(2)]TaMe(3) in the presence of PMe(3), followed by the reaction of ethylene with the resulting trihydride. Crystallographic and NMR data indicate the presence of a beta-agostic interaction between the ethyl group and tantalum center in [P(2)N(2)]Ta(C(2)H(4))Et. Partially deuterated analogues of [P(2)N(2)]Ta(C(2)H(4))Et show a large isotopic perturbation of resonance for both the beta-protons and the alpha-protons of the ethyl group, indicative of an equilibrium between a beta-agostic and an alpha-agostic interaction for the ethyl group in solution. An EXSY spectrum demonstrates that an additional fluxional process occurs that exchanges all of the (1)H environments of the ethyl and ethylene ligands. The mechanism of this exchange is believed to involve the direct transfer of the beta-agostic hydrogen atom from the ethyl group to the ethylene ligand, via the so-called beta-hydrogen transfer process.     

Polymer imprinting with iron-oxo-hydroxo clusters: [Fe6O2(OH)2(O2CC(Cl)=CH2)12(H2O)2], [Fe6O2(OH)2(O2C-Ph-(CH)=CH2)12(H2O)2] and [{Fe(O2CC(Cl)=CH2)(OMe)2}10

We report the syntheses of imprinted polymers using iron-oxo-hydroxo clusters as templates. Three new iron clusters, [Fe(6)O(2)(OH)(2)(O(2)CC(Cl)=CH(2))(12)(H(2)O)(2)] (1), [{Fe(O(2)CC(Cl)=CH(2))(OMe)(2)}(10)] (2) and [Fe(6)O(2)(OH)(2)(O(2)C-Ph-(CH)=CH(2))(12)(H(2)O)(2)] (3) have been prepared from commercially-available carboxylic acids. Cluster-imprinted-polymers (CIPs) of 1, 2 and 3 were prepared with ethylene glycol dimethacrylate monomer, and of 1 with methyl methacrylate monomer. The imprinted sites within the CIPs were examined using EXAFS and diffuse reflectance UV/vis spectroscopy, demonstrating that the clusters 1, 2 and 3 were incorporated intact within the polymers. Extraction of the clusters from the CIPs imprinted with 1 and 3 gave new polymers that showed evidence of an imprinting effect.     

Copper and Bismuth Complexes Containing Dipyridyl gem-Diolato Ligands: Bi(III)(2)[(2-Py)(2)CO(OH)](2)(O(2)CCF(3))(4)(THF)(2), Cu(II)[(2-Py)(2)CO(OH)](2)(HO(2)CCH(3))(2), and Cu(II)(4)[(2-Py)(2)CO(OH)](2)(O(2)CCH(3))(6)(H(2)O)(2), a Ferromagnetically Coupled Tetranuclear Copper(II) Chain

The reactions of the singly deprotonated di-2-pyridylmethanediol ligand (dpmdH(-)) with copper(II) and bismuth(III) have been investigated. A new dinuclear bismuth(III) complex Bi(2)(dpmdH)(2)(O(2)CCF(3))(4)(THF)(2), 1, has been obtained by the reaction of BiPh(3) with di-2-pyridyl ketone in the presence of HO(2)CCF(3) in tetrahydrofuran (THF). The reaction of Cu(OCH(3))(2) with di-2-pyridyl ketone, H(2)O, and acetic acid in a 1:2:2:2 ratio yielded a mononuclear complex Cu[(2-Py)(2)CO(OH)](2)(HO(2)CCH(3))(2), 2, while the reaction of Cu(OAC)(2)(H(2)O) with di-2-pyridyl ketone and acetic acid in a 2:1:1 ratio yielded a tetranuclear complex Cu(4)[(2-Py)(2)CO(OH)](2)(O(2)CCH(3))(6)(H(2)O)(2), 3. The structures of these complexes were determined by single-crystal X-ray diffraction analyses. Three different bonding modes of the dpmdH(-) ligand were observed in compounds 1-3. In 2, the dpmdH(-) ligand functions as a tridentate chelate to the copper center and forms a hydrogen bond between the OH group and the noncoordinating HO(2)CCH(3) molecule. In 1 and 3, the dpmdH(-) ligand functions as a bridging ligand to two metal centers through the oxygen atom. The two pyridyl groups of the dpmdH(-) ligand are bound to one bismuth(III) center in 1, while in 3 they are bound two copper(II) centers, respectively. Compound 3 has an unusual one dimensional hydrogen bonded extended structure. The intramolecular magnetic interaction in 3 has been found to be dominated by ferromagnetism. Crystal data: 1, C(38)H(34)N(4)O(14)F(12)Bi(2), triclinic P&onemacr;, a = 11.764(3) ?, b = 11.949(3) ?, c = 9.737(1) ?, alpha =101.36(2) degrees, beta = 105.64(2) degrees, gamma = 63.79(2) degrees, Z = 1; 2, C(26)H(26)N(4)O(8)Cu/CH(2)Cl(2), monoclinic C2/c, a = 25.51(3) ?, b = 7.861(7) ?, c = 16.24(2) ?, beta = 113.08(9) degrees, Z = 4; 3, C(34)H(40)N(4)O(18)Cu(4)/CH(2)Cl(2), triclinic P&onemacr;, a = 10.494(2) ?, b = 13.885(2) ?, c = 7.900(4) ?, alpha =106.52(2) degrees, beta = 90.85(3) degrees, gamma = 94.12(1) degrees, Z = 1.     

Sensitive detection of H(2)O(2) and H(2)O(2)-related reactant with Ru(bipy)(2)(7,8-dimethyl-dipyridophenazine)(2+) and oligodeoxyribonucleotide

A sensor for H(2)O(2) and H(2)O(2)-related reactant was constructed with oligonucleotides and Ru(bipy)(2)dppx(2+) (bipy = 2,2'-bipyridine, dppx = 7,8-dimethyl-dipyridophenazine), which was performed by converting the H(2)O(2)-induced DNA cleavage into the change of luminescence. The 'DNA light switch' Ru(bipy)(2)dppx(2+) could emit strong luminescence in the presence of dsDNA. DNA cleavage occurred upon addition of H(2)O(2) due to the Fenton reaction, which resulted in the decrease of the luminescence of Ru(bipy)(2)dppx(2+). Therefore, the luminescence intensity depended on the concentration of H(2)O(2) and H(2)O(2)-related reactants, and the detection limits for H(2)O(2), uric acid and cholesterol were 0.20 μM, 0.46 μM and 1.25 μM, respectively. The recovery varied between 94.0% and 105.0% when the assay was applied to the determination of uric acid and cholesterol in biological samples, which demonstrated the good practicability of the assay.