Isolation of the novel dirhodium(II/II) thiolate compound Rh(2)(eta(1)-C(6)H(5)S)(2)(mu-C(6)H(5)S)(2)(bpy)(2)

The reaction of the anticancer active compound [Rh(2)(mu-O(2)CCH(3))(2)(bpy)(2)(CH(3)CN)(2)][BF(4)](2) (1) (bpy = 2,2'-bipyridine) with NaC(6)H(5)S under anaerobic conditions yields Rh(2)(eta(1)-C(6)H(5)S)(2)(mu-C(6)H(5)S)(2)(bpy)(2).CH(3)OH (2), which was characterized by UV-visible, IR, and (1)H NMR spectroscopies as well as single-crystal X-ray crystallography. Compound 2 crystallizes as dark red platelets in the monoclinic space group C2/c with cell parameters a = 20.398(4) A, b = 11.861(2) A, c = 17.417(4) A, beta = 108.98 degrees, V = 3984.9(14) A(3), Z = 4. The main structural features are the presence of a [Rh(2)](4+) core with a Rh-Rh distance of 2.549(2) A bridged by two benzene thiolate ligands in a butterfly-type arrangement. The axial positions of the [Rh(2)](4+) core are occupied by two terminal benzene thiolates. Cyclic voltammetric studies of 2 reveal that the compound exhibits an irreversible oxidation at +0.046 V in CH(3)CN, which is in accord with the fact that the compound readily oxidizes in the presence of O(2). The fact that this unusual dirhodium(II/II) thiolate compound is formed under these conditions is an important first step in understanding the metabolism of dirhodium anticancer active compounds with thiol-containing peptides and proteins.     

Anion-directed crystallization of coordination polymers: syntheses and characterization of Cu(4)(2-pzc)(4)(H(2)O)(8)(Mo(8)O(26)).2H(2)O and Cu(3)(2-pzc)(4)(H(2)O)(2)(V(10)O(28)H(4)).6.5H(2)O (2-pzc = 2-pyrazinecarboxylate)

Two new copper 2-pyrazinecarboxylate (2-pzc) coordination polymers incorporating [Mo(8)O(26)](4-) and [V(10)O(28)H(4)](2-) anions were synthesized and structurally characterized: Cu(4)(2-pzc)(4))(H(2)O)(8)(Mo(8)O(26)).2H(2)O (1) and Cu(3)(2-pzc)(4)(H(2)O)(2)(V(10)O(28)H(4)).6.5H(2)O (2). Crystal data: 1, monoclinic, space group P2(1)/n, a = 11.1547(5) A, b = 13.4149(6) A, c = 15.9633(7) A, beta = 90.816(1) degrees; 2, triclinic, space group P1, a = 10.5896(10) A, b = 10.7921(10) A, c = 13.5168(13) A, alpha = 104.689(2) degrees, beta = 99.103(2) degrees, gamma = 113.419(2) degrees. Compound 1 contains [Cu(2-pzc)(H(2)O)(2)] chains charge-balanced by [Mo(8)O(26)](4-) anions. In compound 2, layers of [Cu(3)(2-pzc)(4)(H(2)O)(2)] form cavities that are filled with [V(10)O(28)H(4)](2-) anions. The magnetic properties of both compounds are described.     

Hydrothermal synthesis in the system Ni(OH)(2)-NiSO(4): nuclear and magnetic structures and magnetic properties of Ni(3)(OH)(2)(SO(4))(2)(H(2)O)(2)

We present the synthesis, characterization by DT-TGA and IR, single crystal X-ray nuclear structure at 300 K, nuclear and magnetic structure from neutron powder diffraction on a deuterated sample at 1.4 K, and magnetic properties as a function of temperature and magnetic field of Ni(3)(OH)(2)(SO(4))(2)(H(2)O)(2). The structure is formed of chains, parallel to the c-axis, of edge-sharing Ni(1)O(6) octahedra, connected by the corners of Ni(2)O(6) octahedra to form corrugated sheets along the bc-plane. The sheets are connected to one another by the sulfate groups to form the 3D network. The magnetic properties measured by ac and dc magnetization, isothermal magnetization at 2 K, and heat capacity are characterized by a transition from a paramagnet (C = 3.954 emu K/mol and theta = -31 K) to a canted antiferromagnet at T(N) = 29 K with an estimated canting angle of 0.2-0.3 degrees. Deduced from powder neutron diffraction data, the magnetic structure is modeled by alternate pairs of Ni(1) within a chain having their moments pointing along [010] and [010], respectively. The moments of Ni(2) atoms are oppositely oriented with respect to their adjacent pairs. The resulting structure is that of a compensated arrangement of moments within one layer, comprising one ferromagnetic and three antiferromagnetic superexchange pathways between the nickel atoms.     

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.     

Cu(2)[o-Br-C(6)H(3)(CO(2))(2)](2)(H(2)O)(2).(DMF)(8)(H(2)O)(2): a framework deliberately designed to have the NbO structure type.

The synthesis of an NbO-type metal-organic framework was achieved by design: o-Br-BDC (BDC = benzenedicarboxylate) was used to direct the formation of Cu2(CO2)4 paddle wheel units at 90 degrees to each other and thus yield the target network. The compound was formulated as Cu2[o-Br-BDC]2(H2O)2.(DMF)8(H2O)2 (MOF-101) and characterized by single-crystal X-ray diffraction [cubic, space group Imm (No. 229) with a = 21.607(3) A, V = 10088(2) A3, Z = 6], which fully confirmed the presence of the expected structure. Despite having very large apertures and voids, MOF-101 has a noninterpenetrated structure, an intriguing observation that is discussed in the context of dual structures.     

N,N'-diisopropyl-N'-bis(trimethylsilyl)guanidinate ligand as a supporting coordination environment in yttrium chemistry. Synthesis, structure, and properties of complexes [(Me(3)Si)(2)NC(Ni-Pr)(2)]YCl(2)(THF)(2), [(Me(3)Si)(2)NC(Ni-Pr)(2)]Y(CH(2)SiMe(3))(2)(THF)(2), and [(Me(3)Si)(2)NC(Ni-Pr)(2)]Y[(mu-H)(mu-Et)(2)BEt](2)(THF)

The reaction of anhydrous YCl3 with an equimolar amount of lithium N,N'-diisopropyl-N' '-bis(trimethylsilyl)guanidinate, Li[(Me3Si)2NC(Ni-Pr)2], in tetrahydrofuran (THF) afforded the monomeric monoguanidinate dichloro complex {(Me3Si)2NC(Ni-Pr)2}YCl2(THF)2 (1). Alkylation of complex 1 with 2 equiv of LiCH2SiMe3 in hexane at 0 degrees C yielded the monomeric salt-free dialkyl complex {(Me3Si)2NC(Ni-Pr)2}Y(CH2SiMe3)2(THF)2 (2). The bis(triethylborohydride) complex [(Me3Si)2NC(Ni-Pr)2]Y[(mu-H)(mu-Et)2BEt]2(THF) (5) was prepared by the reaction of complex 1 with 2 equiv of LiBEt3H in a toluene-THF mixture at 0 degrees C. The complexes 1, 2, and 5 were structurally characterized. Complex 2 as well as the systems 2-Ph3B, 2-Ph3B-MAO, and 1-MAO (MAO = methylaluminoxanes) in toluene were inactive in ethylene polymerization, while the product obtained in situ from the reaction of complex 2 with a 2-fold molar excess of PhSiH3 in toluene polymerized ethylene with moderate activity.     

Tetranuclear and Octanuclear Manganese Carboxylate Clusters: Preparation and Reactivity of (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(9)(H(2)O)] and Synthesis of (NBu(n)(4))(2)[Mn(8)O(4)(O(2)CPh)(12)(Et(2)mal)(2)(H(2)O)(2)] with a "Linked-Butterfly" Structure

The reaction of Mn(O(2)CPh)(2).2H(2)O and PhCO(2)H in EtOH/MeCN with NBu(n)(4)MnO(4) gives (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(9)(H(2)O)] (4) in high yield (85-95%). Complex 4 crystallizes in monoclinic space group P2(1)/c with the following unit cell parameters at -129 degrees C: a = 17.394(3) ?, b = 19.040(3) ?, c = 25.660(5) ?, beta = 103.51(1) degrees, V = 8262.7 ?(3), Z = 4; the structure was refined on F to R (R(w)) = 9.11% (9.26%) using 4590 unique reflections with F > 2.33sigma(F). The anion of 4 consists of a [Mn(4)(&mgr;(3)-O)(2)](8+) core with a "butterfly" disposition of four Mn(III) atoms. In addition to seven bridging PhCO(2)(-) groups, there is a chelating PhCO(2)(-) group at one "wingtip" Mn atom and terminal PhCO(2)(-) and H(2)O groups at the other. Complex 4 is an excellent steppingstone to other [Mn(4)O(2)]-containing species. Treatment of 4 with 2,2-diethylmalonate (2 equiv) leads to isolation of (NBu(n)(4))(2)[Mn(8)O(4)(O(2)CPh)(12)(Et(2)mal)(2)(H(2)O)(2)] (5) in 45% yield after recrystallization. Complex 5 is mixed-valent (2Mn(II),6Mn(III)) and contains an [Mn(8)O(4)](14+) core that consists of two [Mn(4)O(2)](7+) (Mn(II),3Mn(III)) butterfly units linked together by one of the &mgr;(3)-O(2)(-) ions in each unit bridging to one of the body Mn atoms in the other unit, and thus converting to &mgr;(4)-O(2)(-) modes. The Mn(II) ions are in wingtip positions. The Et(2)mal(2)(-) groups each bridge two wingtip Mn atoms from different butterfly units, providing additional linkage between the halves of the molecule. Complex 5.4CH(2)Cl(2) crystallizes in monoclinic space group P2(1)/c with the following unit cell parameters at -165 degrees C: a = 16.247(5) ?, b = 27.190(8) ?, c = 17.715(5) ?, beta = 113.95(1) degrees, V = 7152.0 ?(3), Z = 4; the structure was refined on F to R (R(w)) = 8.36 (8.61%) using 4133 unique reflections with F > 3sigma(F). The reaction of 4 with 2 equiv of bpy or picolinic acid (picH) yields the known complex Mn(4)O(2)(O(2)CPh)(7)(bpy)(2) (2), containing Mn(II),3Mn(III), or (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(7)(pic)(2)] (6), containing 4Mn(III). Treatment of 4 with dibenzoylmethane (dbmH, 2 equiv) gives the mono-chelate product (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(8)(dbm)] (7); ligation of a second chelate group requires treatment of 7 with Na(dbm), which yields (NBu(n)(4))[Mn(4)O(2)(O(2)CPh)(7)(dbm)(2)] (8). Complexes 7 and 8 both contain a [Mn(4)O(2)](8+) (4Mn(III)) butterfly unit. Complex 7 contains chelating dbm(-) and chelating PhCO(2)(-) at the two wingtip positions, whereas 8 contains two chelating dbm(-) groups at these positions, as in 2 and 6. Complex 7.2CH(2)Cl(2) crystallizes in monoclinic space group P2(1) with the following unit cell parameters at -170 degrees C: a = 18.169(3) ?, b = 19.678(4) ?, c = 25.036(4) ?, beta = 101.49(1) degrees, V = 8771.7 ?(3), Z = 4; the structure was refined on F to R (R(w)) = 7.36% (7.59%) using 10 782 unique reflections with F > 3sigma(F). Variable-temperature magnetic susceptibility studies have been carried out on powdered samples of complexes 2 and 5 in a 10.0 kG field in the 5.0-320.0 K range. The effective magnetic moment (&mgr;(eff)) for 2 gradually decreases from 8.61 &mgr;(B) per molecule at 320.0 K to 5.71 &mgr;(B) at 13.0 K and then increases slightly to 5.91 &mgr;(B) at 5.0 K. For 5, &mgr;(eff) gradually decreases from 10.54 &mgr;(B) per molecule at 320.0 K to 8.42 &mgr;(B) at 40.0 K, followed by a more rapid decrease to 6.02 &mgr;(B) at 5.0 K. On the basis of the crystal structure of 5 showing the single Mn(II) ion in each [Mn(4)O(2)](7+) subcore to be at a wingtip position, the Mn(II) ion in 2 was concluded to be at a wingtip position also. Employing the reasonable approximation that J(w)(b)(Mn(II)/Mn(III)) = J(w)(b)(Mn(III)/M(III)), where J(w)(b) is the magnetic exchange interaction between wingtip (w) and body (b) Mn ions of the indicated oxidation state, a theoretical chi(M) vs T expression was derived and used to fit the experimental molar magnetic susceptibility (chi(M)) vs T data. The obtained fitting parameters were J(w)(b) = -3.9 cm(-)(1), J(b)(b) = -9.2 cm(-)(1), and g = 1.80. These values suggest a S(T) = (5)/(2) ground state spin for 2, which was confirmed by magnetization vs field measurements in the 0.5-50.0 kG magnetic field range and 2.0-30.0 K temperature range. For complex 5, since the two bonds connecting the two [Mn(4)O(2)](7+) units are Jahn-Teller elongated and weak, it was assumed that complex 5 could be treated, to a first approximation, as consisting of weakly-interacting halves; the magnetic susceptibility data for 5 at temperatures >/=40 K were therefore fit to the same theoretical expression as used for 2, and the fitting parameters were J(w)(b) = -14.0 cm(-)(1) and J(b)(b) = -30.5 cm(-)(1), with g = 1.93 (held constant). These values suggest an S(T) = (5)/(2) ground state spin for each [Mn(4)O(2)](7+) unit of 5, as found for 2. The interactions between the subunits are difficult to incorporate into this model, and the true ground state spin value of the entire Mn(8) anion was therefore determined by magnetization vs field studies, which showed the ground state of 5 to be S(T) = 3. The results of the studies on 2 and 5 are considered with respect to spin frustration effects within the [Mn(4)O(2)](7+) units. Complexes 2 and 5 are EPR-active and -silent, respectively, consistent with their S(T) = (5)/(2) and S(T) = 3 ground states, respectively.     

Influence of the Peripheral Ligand Atoms on the Exchange Interaction in Oxalato-Bridged Nickel(II) Complexes: An Orbital Model. Crystal Structures and Magnetic Properties of (H(3)dien)(2)[Ni(2)(ox)(5)].12H(2)O and [Ni(2)(dien)(2)(H(2)O)(2)(ox)]Cl(2)

Two nickel(II) complexes of formula (H(3)dien)(2)[Ni(2)(ox)(5)].12H(2)O (1) and [Ni(2)(dien)(2)(H(2)O)(2)(ox)]Cl(2) (2) (dien = diethylenetriamine and ox = oxalate dianion) have been synthesized and characterized by single-crystal X-ray diffraction. 1 crystallizes in the orthorhombic system, space group Abnn, with a = 15.386(4) ?, b = 15.710(4) ?, c = 17.071(4) ?, and Z = 4. 2 crystallizes in the monoclinic system, space group P2(1)/c, with a = 10.579(1) ?, b = 7.258(1) ?, c = 13.326(1) ?, beta = 93.52(3) degrees, and Z = 2. The structures of 1 and 2 consist of dinuclear oxalato-bridged nickel(II) units which contain bidentate oxalate (1) and tridentate dien in the fac-conformation (2) as terminal ligands. Both features, oxalato as a peripheral ligand and dien in the fac-conformation (instead of its usual mer-conformation), are unprecedented in the coordination chemistry of nickel(II). The nickel atom is six-coordinated in both compounds, the chromophores being NiO(6) (1) and NiN(3)O(3) (2). The Ni-O(ox) bond distances at the bridge (2.072(4) ? in 1 and 2.11(1) and 2.125(9) ? in 2) are somewhat longer than those concerning the terminal oxalate (2.037(5) and 2.035(3) ? in 1). Magnetic susceptibility data of 1 and 2 in the temperature range 4.2-300 K show the occurrence of intramolecular antiferromagnetic coupling with J = -22.8 (1) and -28.8 (2) cm(-)(1) (J being the parameter of the exchange Hamiltonian H = -JS(A).S(B)). The observed value of -J in the investigated oxalato-bridged nickel(II) complexes, which can vary from 22 to 39 cm(-)(1), is strongly dependent on the nature of the donor atoms from the peripheral ligands. This influence has been analyzed and rationalized through extended Hückel calculations.     

Synthesis and structure of W(eta(2)-mp)(2)(CO)(3) (mp = monoanion of 2-mercaptopyridine) and its reactions with 2,2'-pyridine disulfide and/or NO to yield W(eta(2)-mp)(4), W(eta(2)-mp)(2)(NO)(2), and W(eta(2)-mp)(3)(NO)

Oxidative addition of the sulfur-sulfur bond of 2,2'-pyridine disulfide (C(5)H(4)NS-SC(5)H(4)N) with L(3)W(CO)(3) [L = pyridine, (1)/(3)CHPT; CHPT = cycloheptatriene] in methylene chloride solution yields the seven-coordinate W(II) thiolate complex W(eta(2)-mp)(2)(CO)(3) (mp = monoanion of 2-mercaptopyridine). This complex undergoes slow further oxidative addition with additional pyridine disulfide, yielding W(eta(2)- mp)(4). Reaction of W(eta(2)-mp)(2)(CO)(3) with NO results in quantitative formation of the six-coordinate W(0) complex W(eta(2)-mp)(2)(NO)(2). Reaction of W(eta(2)-mp)(2)(CO)(3) with NO in the presence of added pyridine disulfide yields the seven-coordinate W(II) nitrosyl complex W(eta(2)-mp)(3)(NO) as well as W(eta(2)-mp)(2)(NO)(2) and trace amounts of W(eta(2)-mp)(4). The complex W(eta(2)-mp)(3)(NO) is formed during the course of the reaction and not by reaction of W(eta(2)-mp)(4) or W(eta(2)-mp)(2)(NO)(2) with NO under these conditions. The crystal structures of W(eta(2)- mp)(2)(CO)(3), W(eta(2)-mp)(2)(NO)(2), and W(eta(2)-mp)(3)(NO) are reported.     

Mechanism of protonation of [Pt(3)(mu-PBu(t)(2))3(H)(CO)2], yielding the hydride-bridged [Pt(3)(mu-PBu(t)(2))2(mu-H)(PBu(t)(2)H)(CO)2]OTf (Tf=CF(3)SO(2)), and the spectroscopic and theoretical characterization of a kinetic intermediate

The reaction of the Pt(I)Pt(I)Pt(II) triangulo cluster Pt(3)(micro-PBu(t)()(2))(3)(H)(CO)(2) (1) with TfOH (Tf = CF(3)SO(2)) affords the hydride-bridged cationic derivative [Pt(3)(mu-PBu(t)()(2))(2)(mu-H)(PBu(t)()(2)H)(CO)(2)]OTf (2). With TfOD the reaction gives selectively [Pt(3)(mu-PBu(t)(2))(2)(mu-D)(PBu(t)(2)H)(CO)(2)]OTf (2-D(1)), implying that the proton is transferred to a metal center while a P-H bond is formed by the reductive coupling of one of the bridging phosphides and the terminal hydride ligand of the reagent. The reaction proceeds through the formation of a thermally unstable kinetic intermediate which was characterized at low temperatures, and was suggested to be the CO-hydrogen-bonded (or protonated) [Pt(3)(mu-PBu(t)(2))(3)(H)(CO)(2)].HOTf (3). An ab initio theoretical study predicts a hydrogen-bonded complex or a proton-transfer tight ion pair as a possible candidate for the structure of the kinetic intermediate.     

Layered Double Hydroxides Intercalated by Polyoxometalate Anions with Keggin (alpha-H(2)W(12)O(40)(6)(-)), Dawson (alpha-P(2)W(18)O(62)(6)(-)), and Finke (Co(4)(H(2)O)(2)(PW(9)O(34))(2)(10)(-)) Structures

The pillaring of Mg(3)Al layered double hydroxides (LDHs) by the title polyoxometalates (POMs) was accomplished by ion exchange reaction of the LDH-hydroxide and -adipate precursors with the POM anion at ambient or refluxing temperatures. The structural, thermal and textural properties of the LDH-POM intercalates were elucidated based on XRD, FTIR, TEM, EDS, and N(2) adsorption-desorption studies. A gallery height of approximately 10 ? was observed for the LDH intercalated by the symmetrical Keggin POM, whereas two different gallery heights were found for the cylindrical Dawson (14.5 and 12.8 ?) and Finke (13.3 and 12.6 ?) anions, depending on the preparation temperature. The differences in POM orientations were rationalized in terms of different electrostatic and hydrogen-bonding interactions between the POM pillars and the LDH layers. Upon thermal treatment at >/=100 degrees C, the intercalated Dawson and Finke POM ions exhibited only one gallery orientation, regardless of synthesis conditions. The crystalline microporous structures were retained upon heating each LDH-POM intercalate in N(2) to 200 degrees C. Pillaring in all cases was accompanied by the formation of a poorly ordered Mg(2+)/Al(3+) salt impurity that formed on the external surfaces of the LDH crystals.     

Modeling the Formation of Molybdenum Oxides from Alkoxides: Crystal Structures of [Mo(4)O(4)Cl(4)(&mgr;(2)-OEt)(4)(HOEt)(2)(&mgr;(3)-O)(2)] and [PPN](+)[Et(3)NH](+)[Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-)

The reactions of the binuclear oxomolybdenum(V) complex [Cl(2)(O)Mo(&mgr;-OEt)(2)(&mgr;-HOEt)Mo(O)Cl(2)] (1) with Me(3)Si(allyl) and SbF(3) produce the compounds [Mo(6)O(6)Cl(6)(&mgr;(3)-O)(2)(&mgr;(2)-OEt)(6)(&mgr;(2)-Cl)(2)] (2) and [Mo(8)O(8)Cl(6)(&mgr;(3)-O)(4)(OH)(2)(&mgr;(2)-OH)(4)(&mgr;(2)-OEt)(4)(HOEt)(4)] (3), respectively. Treatment of 1 with the Lewis base PMe(3) affords the tetrameric complex [Mo(4)O(4)Cl(4)(&mgr;(2)-OEt)(4)(HOEt)(2)(&mgr;(3)-O)(2)] (4), which represents another link in the chain of clusters produced by the reactions of 1 and simulating the build-up of polymeric molybdenum oxides by sol-gel methods. The crystal structure of 4 has been determined [C(12)H(32)Cl(4)Mo(4)O(12), triclinic, P&onemacr;, a = 7.376(2) ?, b = 8.807(3) ?, c = 11.467(4) ?, alpha = 109.61(1) degrees, beta = 92.12(3) degrees, gamma = 103.75(2) degrees, Z = 1]. By contrast, reaction of 1 with the nitrogen base NEt(3), followed by treatment with [PPN]Cl.2H(2)O ([PPN](+) = [Ph(3)P=N=PPh(3)](+)), gives the complex [PPN](+)[Et(3)NH](+)[Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-) (6) in 90% yield. Its crystal structure [C(36)H(30)Cl(4)MoNOP(2), triclinic, Pna2(1), a = 21.470(6) ?, b = 16.765(2) ?, c = 9.6155(14) ?, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 16] includes the anion [Cl(2)(O)Mo(&mgr;(2)-O)(2)Mo(O)Cl(2)](2)(-), which is a charged derivative of the species forming the gels in sol-gel processes starting from chloromolybdenum ethoxides. Furthermore, compound 1 is found to be catalytically active in esterification and dehydration reactions of alcohols.     

Synthesis and crystal structures of (fulvalene)W(2)(SH)(2)(CO)(6), (fulvalene)W(2)(mu-S(2))(CO)(6), and (fulvalene)W(2)(mu-S)(CO)(6): low valent tungsten carbonyl sulfide and disulfide complexes stabilized by the bridging fulvalene ligand

Reaction of FvW(2)(H)(2)(CO)(6) with 2/8S(8) in THF results in rapid and quantitative formation of FvW(2)(SH)(2)(CO)(6). The crystal structure of this complex is reported and shows that the two tungsten-hydrosulfide groups are on opposite faces of the fulvalene ligand in an anti configuration. Nevertheless, treatment of FvW(2)(SH)(2)(CO)(6) (1) with PhN[double bond]NPh produces FvW(2)(mu-S(2))(CO)(6) (2) and Ph(H)NN(H)Ph. The crystal structure of the bridging disulfide, which cocrystallizes with 1 in a 2:1 ratio, is also described. Exposure of 2 equiv of *CrCp*(CO)(3) to 1 effects similar H atom transfers yielding 2 HCrCp*(CO)(3) and 2. Attempts to obtain crystals of the latter from solutions derived from this reaction mixture furnished a third product, FvW(2)(mu-S)(CO)(6) (3), which was analyzed crystallographically. The enthalpy of sulfur atom insertion into FvW(2)(H)(2)(CO)(6), yielding 1, has been measured by solution calorimetry.     

Reaction properties of the trans-hyponitrite complex [Ru2(CO)4(mu-H)(mu-PBu(t)2)(mu-Ph2PCH2PPh2)(mu-eta2-ONNO)

The protonation of [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNO)] (1) with HBF(4) occurs at the oxygen of the noncoordinating side of the trans-hyponitrite ligand to give [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOH)][BF(4)] (2) in good yield. The monoprotonated hyponitrite in 2 is deprotonated easily by strong bases to regenerate 1. Furthermore, 1 reacts with the methylating reagent [Me(3)O][BF(4)] to afford [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOMe)][BF(4)] (3). The molecular structures of 2 and 3 have been determined crystallographically, and the structure of 2 is discussed with the results of the DFT/B3LYP calculations on the model complex [Ru(2)(CO)(4)(mu-H)(mu-PH(2))(mu-H(2)PCH(2)PH(2))(mu-eta(2)-ONNOH)](+) (2a). Moreover, the thermolysis of 2 in ethanol affords [Ru(2)(CO)(4)(mu-H)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)][BF(4)] (4) in high yield, and the deprotonation of 4 by DBU in THF yields the novel complex [Ru(2)(CO)(4)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)] (5).     

Reactions of the Dirhenium(II) Complexes Re(2)X(4)(dppm)(2) (X = Cl, Br; dppm = Ph(2)PCH(2)PPh(2)) with Isocyanides. 10.(1) Synthesis and Characterization of the Complex [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3) and Several Isomeric Forms of [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)]Y (Y = PF(6), O(3)SCF(3))

The reactions of the unsymmetrical, coordinatively unsaturated dirhenium(II) complexes [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)]Y (XylNC = 2,6-dimethylphenyl isocyanide; Y = O(3)SCF(3) (3a), PF(6) (3b)) with XylNC afford at least three isomeric forms of the complex cation [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](+). Two forms have very similar bis(&mgr;-halo)-bridged edge-sharing bioctahedral structures of the type [(CO)BrRe(&mgr;-Br)(2)(&mgr;-dppm)(2)Re(CNXyl)(2)]Y (Y = O(3)SCF(3) (4a/4a'), PF(6) (4b/4b')), while the third is an open bioctahedron [(XylNC)(2)BrRe(&mgr;-dppm)(2)ReBr(2)(CO)]Y (Y = O(3)SCF(3) (5a), PF(6) (5b)). While the analogous chloro complex cation [Re(2)Cl(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](+) was previously shown to exist in three isomeric forms, only one of these has been found to be structurally similar to the bromo complexes (i.e. the isomer analogous to 5a and 5b). The reaction of 3a with CO gives the salt [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3) (7), in which the edge-sharing bioctahedral cation [(XylNC)BrRe(&mgr;-Br)(&mgr;-CO)(&mgr;-dppm)(2)ReBr(CO)](+) has an all-cis arrangement of pi-acceptor ligands. The Re-Re distances in the structures of 4b', 5a, and 7 are 3.0456(8), 2.3792(7), and 2.5853(13) ?, respectively, and accord with formal Re-Re bond orders of 1, 3, and 2, respectively. Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)](PF(6))(0.78)(ReO(4))(0.22).CH(2)Cl(2) (4b') at 295 K: monoclinic space group P2(1)/n (No. 14) with a = 19.845(4) ?, b = 16.945(5) ?, c = 21.759(3) ?, beta = 105.856(13) degrees, V = 7038(5) ?(3), and Z = 4. The structure was refined to R = 0.060 (R(w) = 0.145) for 14 245 data (F(o)(2) > 2sigma(F(o)(2))). Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(CNXyl)(2)]O(3)SCF(3).C(6)H(6) (5a) at 173 K: monoclinic space group P2(1)/n (No. 14) with a = 14.785(3) ?, b = 15.289(4) ?, c = 32.067(5) ?, beta = 100.87(2) degrees, V=7118(5) ?(3), and Z = 4. The structure was refined to R = 0.046 (R(w) = 0.055) for 6962 data (I > 3.0sigma(I)). Crystal data for [Re(2)Br(3)(&mgr;-dppm)(2)(CO)(2)(CNXyl)]O(3)SCF(3).Me(2)CHC(O)Me (7) at 295 K: monoclinic space group P2(1)/n (No. 14) with a = 14.951(2) ?, b = 12.4180(19) ?, c = 40.600(5) ?, beta = 89.993(11) degrees, V = 7537(3) ?(3), and Z = 4. The structure was refined to R = 0.074 (R(w) = 0.088) for 6595 data (I > 3.0sigma(I)).     

Fluoride-bridged {Ln(2)Cr(2)} polynuclear complexes from semi-labile mer-[CrF(3)(py)(3)] and [Ln(hfac)(3)(H(2)O)(2)

The trifluorido complex mer-[CrF(3)(py)(3)] (py = pyridine) reacts with 1 equiv. of [Ln(hfac)(3)(H(2)O)(2)] and depending on the solvent forms the tetranuclear clusters [Cr(2)Ln(2)(μ-F)(4)(μ-OH)(2)(py)(4)(hfac)(6)], 1Ln, and [Cr(2)Ln(2)(μ-F)(4)F(2)(py)(6)(hfac)(6)], 2Ln, in acetonitrile and 1,2-dichloroethane, respectively (Ln = Y, Gd, Tb, Dy, Ho, and Er; hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone). Reaction with [Dy(hfac)(3)(H(2)O)(2)] in dichloromethane produces the dinuclear cluster [CrDy(μ-F)F(OH(2))(py)(3)(hfac)(4)], 3Dy. All the clusters feature fluoride bridges between the chromium(iii) and lanthanide(iii) centres. Fits of susceptibility data for 1Gd and 2Gd reveal the fluoride-mediated chromium(iii)-lanthanide(iii) exchange interactions to be 0.43(5) cm(-1) and 0.57(7) cm(-1), respectively (in the convention). Heat capacity measurements on 2Gd reveal a moderate magneto-caloric effect (MCE) reaching -ΔS(m)(T) = 11.4 J kg(-1) K(-1) for ΔB(0) = 9 T → 0 T at T = 4.1 K. Out-of-phase alternating-current susceptibility (χ') signals are observed for 1Dy, 2Dy and 2Tb, demonstrating slow relaxation of the magnetization.