Formation of cyclodimeric (sp(2)-C(1))-bridged Cp/-oxido ("CpC(1)O"M(IV)X(2)) group 4 metal Ziegler-Natta catalyst systems--how important is the "constrained geometry" effect?

Deprotonation of sodium acetylcyclopentadienide (11) was achieved by treatment with LDA in THF to generate the dianion equivalent [Cp-C(=CH(2))-O](2-)(12). Transmetalation with Cl(2)Ti(NMe(2))(2) gave ([Cp-C(=CH(2))-O]Ti(NMe(2))(2))(2) (17); treatment of 12 with Cl(2)Zr(NEt(2))(2)(THF)(2) furnished (([Cp-C(=CH(2))-O]Zr(NEt(2))(2))(2) (18). Cryoscopy in benzene revealed a dimeric structure of 18 in solution. Complex 18 was characterized further by an X-ray crystal structure analysis and by DFT calculations. The two zirconium centers of 18 are connected by means of two symmetry-equivalent eta(5):kappaO[Cp-C(=CH(2))-O] ligands. The ligand backbone shows no specific steric constraints, different from the formally related "constrained geometry" systems such as [Cp-SiMe(2)-NCMe(3)]Zr(NMe(2))(2) (1b). Nevertheless, upon treatment with MAO the CpCO group 4 metal complex system (18) generates an active homogeneous Ziegler-Natta catalyst for effective ethene/1-octene copolymerization, with up to 20% 1-octene having become incorporated in the resulting copolymer at 90 degrees C.     

The synthesis of W-O-W μ-oxo clusters by hydrolysis of tungsten aminoalkoxides and their structural characterisation

The tungsten aminoalkoxides W(O)(OPr(i))(3)L [L = dmae, OCH(2)CH(2)NMe(2) (1); bdmap, OCH(CH(2)NMe(2))(2) (2); tdmap, OC(CH(2)NMe(2))(3) (3)] have been synthesised. Controlled hydrolysis of 1-3 has allowed isolation of W(4)O(4)(μ-O)(6)(dmae)(4) (4), W(4)O(4)(μ-O)(4)(OPr(i))(4)(bdmap)(4) (5), W(6)O(6)(μ-O)(9)(tdmap)(6) (6), W(4)O(4)(μ-O)(6)(tdmap)(4) (7), W(4)O(4)(μ-O)(6)(tdmap)(4)·4H(2)O (7a), all of which have been characterised by X-ray crystallography. 4, 7, 7a each embody a W(4)O(6) core with adamantane structure, 5 incorporates a folded W(4)O(4) square and 6 has a trigonal prismatic W(6)O(9) at its heart. 7 decomposes in air at to give orthorhombic WO(3), while 1-3 decomposed under an autogenerated pressure (Reaction under Autogenic Pressure at Elevated Temperatures, RAPET) to form mixtures of carbon-coated WO(x) needles and carbon spherules.     

Molecular precursors to gallium oxide thin films

The donor-functionalised alkoxides [Et(2)Ga(OR)](2)(R = CH(2)CH(2)NMe(2)(1), CH(CH(2)NMe(2))(2)(2), CH(2)CH(2)OMe (3), CH(CH(3))CH(2)NMe(2)(4), C(CH(3))(2)CH(2)OMe (5)) were synthesised by the 1:1 reaction of Et(3)Ga with ROH in hexane or dichloromethane at room temperature. Reaction of Et(3)Ga with excess ROH in refluxing toluene resulted in the isolation of a 1:1 mixture of [Et(2)Ga(OR)](2) and the ethylgallium bisalkoxide [EtGa(OR)(2)](R = CH(2)CH(2)NMe(2)(6) or CH(CH(3))CH(2)NMe(2)(7)). X-ray crystallography showed that compound 6 is monomeric and this complex represents the first structurally characterised monomeric gallium bisalkoxide. Homoleptic gallium trisalkoxides [Ga(OR)(3)](2) were prepared by the 1:6 reaction of [Ga(NMe(2))(3)](2) with ROH (R = CH(2)CH(2)NMe(2)(8), CH(CH(3))CH(2)NMe(2)(9), C(CH(3))(2)CH(2)OMe (10)). The decomposition of compounds 1, 4, 5 and 8 were studied by thermal gravimetric analysis. Low pressure CVD of 1 and 5 resulted in the formation of thin films of crystalline Ga(2)O(3).     

Structural Aspects of Lithium Arenethiolate Complexes with Intramolecular Coordinating Amine Donors

Reaction of aryllithium reagents LiR (R = C(6)H(4)((R)-CH(Me)NMe(2))-2 (1a), C(6)H(3)(CH(2)NMe(2))(2)-2,6 (1b), C(6)H(4)(CH(2)N(Me)CH(2)CH(2)OMe)-2 (1c)) with 1 equiv of sulfur (1/8 S(8)) results in the quantitative formation of the corresponding lithium arenethiolates [Li{SC(6)H(4)((R)-CH(Me)NMe(2))-2}](6) (3), [Li{SC(6)H(3)(CH(2)NMe(2))(2)-2,6}](6) (4), and [Li{SC(6)H(4)(CH(2)N(Me)CH(2)CH(2)OMe)-2}](2) (5). Alternatively, 3 can be prepared by reacting the corresponding arenethiol HSC(6)H(4)((R)-CH(Me)NMe(2))-2 (2) with (n)BuLi. X-ray crystal structures of lithium arenethiolates 3 and 4, reported in abbreviated form, show them to have hexanuclear prismatic and hexanuclear planar structures, respectively, that are unprecedented in lithium thiolate chemistry. The lithium arenethiolate [Li{SC(6)H(4)(CH(2)N(Me)CH(2)CH(2)OMe)-2}](2) (5) is dimeric in the solid state and in solution, and crystals of 5 are monoclinic, space group P2(1)/c, with a = 17.7963(9) ?, b = 8.1281(7) ?, c = 17.1340(10) ?, beta = 108.288(5) degrees, Z = 4, and final R = 0.047 for 4051 reflections with F > 4sigma(F). Hexameric 4 reacts with 1 equiv of lithium iodide and 2 equiv of tetrahydrofuran to form the dinuclear adduct [Li(2)(SAr)(I)(THF)(2)] (6). Crystals of 6 are monoclinic, space group P2(1)/c, with a = 13.0346(10) ?, b = 11.523(3) ?, c = 16.127(3) ?, beta = 94.682(10) degrees, Z = 4, and final R = 0.059 for 3190 reflections with F > 4sigma(F).     

New diamide-diamine ligands and their zirconium and hafnium dichloride and bis(dimethylamide) complexes

The multigram syntheses of the protio ligands (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NHSiMe(2)R)(2) (R = Me, H(2)N(2)NN' 3; R = (t)Bu, H(2)N(2)NN() 4) are described via reactions of the previously reported (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NH(2))(2) (1). A new synthesis of 1 is reported starting from 2-aminomethylpyridine and N-tosylaziridine, proceeding via (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NHTs)(2) (2). Reaction of H(2)N(2)NN' or H(2)N(2)NN* with (n)BuLi gives good yields of the dilithiated derivatives Li(2)N(2)NN' and Li(2)N(2)NN*. Reaction of H(2)N(2)NN' or H(2)N(2)NN* with [MCl(2)(CH(2)SiMe(3))(2)(Et(2)O)(2)] gives the cis-dichloride complexes [MCl(2)(L)] (L = N(2)NN', M = Zr 7 or Hf 8; L = N(2)NN(), M = Zr 9). The corresponding reactions of H(2)N(2)NN' or H(2)N(2)NN* with [Zr(NMe(2))(4)] afford the bis(dimethylamide) derivatives [Zr(NMe(2))(2)(L)] (L = N(2)NN' 10 or N(2)NN* 11). All of these protonolysis reactions proceed smoothly and in good yields. Attempts to prepare the titanium complexes [Ti(X)(2)(N(2)NN')] (X = Cl or NMe(2)) were unsuccessful. The X-ray crystal structures of (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NHTs)(2).EtOH, [ZrCl(2)(N(2)NN')].0.5C(6)H(6), [Zr(NMe(2))(2)(N(2)NN')], and [Zr(NMe(2))(2)(N(2)NN*)] are reported.     

Structural basis for unusually long wavelength charge transfer transitions in complexes [MCl(ECH(2)CH(2)NMe(2))(PR(3))] (E = Te,Se; M = Pt,Pd): experimental results and TD-DFT calculations

A series of new complexes, the blue compounds [PdCl(TeCH(2)CH(2)NMe(2))(PR(3))] (PR(3) = PEt(3), PPr(n)(3), PBu(n)(3), PMe(2)Ph, PMePh(2), PPh(3), PTol(3)) and the red [PtCl(TeCH(2)CH(2)NMe(2))(PR(3))] (PR(3) = PMe(2)Ph, PMePh(2)), were synthesized and studied spectroscopically ((1)H and (31)P NMR, UV/vis) and by cyclic voltammetry. The structures of [PdCl(TeCH(2)CH(2)NMe(2))(PPr(n)(3))] (2b) [PdCl(TeCH(2)CH(2)NMe(2))(PMePh(2))] (2e), [PtCl(TeCH(2)CH(2)NMe(2))(PMePh(2))] (2i), and the related [PtCl(SeCH(2)CH(2)NMe(2))(PEt(3))] (3) were determined crystallographically, revealing a typical pattern of trans-positioned neutral N and P donor atoms in an approximately square planar setting. The molecules 2b, 2e, and 2i were calculated by TD-DFT methodology to understand the origin of the weak (epsilon approximately 200 M(-1) cm(-1)) long-wavelength bands at about 600 nm for Pd/Te complexes such as 2b or 2e, at ca. 460 nm for Pt/Te systems such as 2i, and at about 405 nm for Pt/Se analogues such as 3. These transitions are identified as charge transfer transitions from the selenolato or tellurolato centers to unoccupied orbitals involving mainly the phosphine coligands for the Pt(II) compounds and more delocalized MOs for the Pd(II) analogues. Calculations and electrochemical data were used to rationalize the effects of metal and chalcogen variation.     

Metal-induced coordination inversion and carbon-nitrogen bond rearrangement. Structurally characterized phenyl isocyanate inserted into aluminum methyl compounds and O- and N-bound aluminum compounds

[C(4)H(3)N(CH(2)NMe(2))-2]AlMe(2) (1) is prepared in 88% yield by the reaction of substituted pyrrole [C(4)H(4)N(CH(2)NMe(2))-2] with 1 equiv of AlMe(3) in methylene chloride. Reaction of compound 1 with 1 equiv of phenyl isocyanate in toluene generates a seven-membered cycloaluminum compound [C(4)H(3)N[CH(2)NPh(CONMe(2))]-2] AlMe(2) (2). The phenyl isocyanate was inserted into the aluminum and dimethylamino nitrogen bond and induced an unusual rearrangement which results in C-N bond breaking and formation. A control experiment shows that the reaction of substituted pyrrole [C(4)H(4)N(CH(2)NMe(2))-2] with 1 equiv of phenyl isocyanate in diethyl ether yields a pyrrolyl attached urea derivative [C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NHPh]-1] (3). The demethanation reaction of AlMe(3) with 1 equiv of 3 in methylene chloride at 0 degrees C afforded O-bounded and N-bounded aluminum dimethyl compounds [C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NPh]-1]AlMe(2) (4a) and [C(4)H(3)N(CH(2)NMe(2))-2-[CO(=NPh)]-1]AlMe(2) (4b) in a total 78% yield after recrystallization. Both 4a and 4b are observed in (1)H NMR spectra; however, the relative ratio of 4a and 4b depends on the solvent used. Two equivalents of AlMe(3) was reacted with 3 in methylene chloride to yield a dinuclear aluminum compound AlMe(3)[C(4)H(3)N(CH(2)NMe(2))-2-[C(=O)NPh]-1] AlMe(2) (5). Reaction of 5 with another equivalent of ligand 3 results in the re-formation of compounds 4a and 4b.     

Tuning the [L2Rh···H3B·NR3]+ interaction using phosphine bite angle. Demonstration by the catalytic formation of polyaminoboranes

Efficient catalysts for the dehydrocoupling or dehydropolymerisation of H(3)B·NMe(x)H((3-x)) (x = 1, 2) have been developed by variation of the P-Rh-P angle in {Rh(Ph(2)P(CH(2))(n)PPh(2))}(+) fragments (n = 2-5).     

Synthetic and structural studies of donor-functionalized alkoxy derivatives of gallium

The synthesis of a range of alkyl/chloro-gallium alkoxide and amido/alkoxide compounds was achieved via a series of protonolysis and alcoholysis steps. The initial reaction involved the synthesis of [Me(Cl)Ga{N(SiMe(3))(2)}](2) (1) via methyl group transfer from the reaction of GaCl(3) with two equivalents of LiN(SiMe(3))(2). Reaction of 1 with varying amounts of ROH resulted in the formation of [Me(Cl)Ga(OR)](2) (2, R = CH(2)CH(2)OMe; 3, CH(CH(3))CH(2)NMe(2)), [Me(Cl)Ga{N(SiMe(3))(2)}(μ(2)-OR)Ga(Cl)Me] (4, R = CH(2)CH(2)NMe(2)), or [MeGa(OR)(2)] (5, R = CH(CH(3))CH(2)NMe(2)). Compound 4 represents an intermediate in the formation of dimeric complexes, of the type [Me(Cl)Ga(OR)](2), when formed from compound [Me(Cl)Ga{N(SiMe(3))(2)}](2). A methylgallium amido/alkoxide complex [MeGa{N(SiMe(3))(2)}(OCH(2)CH(2)OMe)](2) (6) was isolated when 2 was further reacted with LiN(SiMe(3))(2). In addition, reaction of 2 with HO(t)Bu resulted in a simple alcohol/alkoxide exchange and formation of [Me(Cl)Ga(O(t)Bu)](2) (7). In contrast to the formation of 1, the in situ reaction of GaCl(3) with one equivalent of LiN(SiMe(3))(2) yielded [Cl(2)Ga{N(SiMe(3))(2)}](2) in low yield, where no methyl group transfer has occurred. Reaction of alcohol with [Cl(2)Ga{N(SiMe(3))(2)}](2) was then found to yield [Cl(2)Ga(OR)](2) (8, R = CH(2)CH(2)NMe(2)), and further reaction of 8 with LiN(SiMe(3))(2) yielded the gallium amido alkoxide complex, [ClGa{N(SiMe(3))(2)}(OR)](2) (9, R = CH(2)CH(2)NMe(2)), similar to 6. The structures of compounds 4, 5, 7, and 8 have been determined by single-crystal X-ray diffraction.     

Synthesis and characterization of heterobimetallic oxo-bridged aluminum-rare earth metal complexes

Reaction of the aluminum hydroxide LAl(OH)[C(Ph)CH(Ph)] (1, L = HC[(CMe)(NAr)](2), Ar = 2,6-iPr(2)C(6)H(3)) with Y(CH(2)SiMe(3))(3)(THF)(2) yielded the oxo-bridged heterobimetallic yttrium dialkyl complex LAl[C(Ph)CH(Ph)](μ-O)Y(CH(2)SiMe(3))(2)(THF)(2) (2). Alkane elimination reaction of 2 with 2-(imino)pyrrole [NN]H ([NN]H = 2-(ArN═CH)-5-tBuC(4)H(2)NH) afforded the yttrium monoalkyl complex LAl[C(Ph)CH(Ph)] (μ-O)Y(CH(2)SiMe(3))[NN](THF)(2) (5). Alternatively, 5 can be prepared in high yield by reaction of 1 with [NN]Y(CH(2)SiMe(3))(2)(THF)(2) (3). The analogous samarium alkyl complex LAl[C(Ph)CH(Ph)](μ-O)Sm(CH(2)SiMe(3))[NN](THF)(2) (6) was prepared similarly. Reactions of 5 and 6 with 1 equiv of iPrOH yielded the corresponding alkoxyl complexes 7 and 8, respectively. The molecular structures of 3, 6, and 8 have been determined by X-ray single-crystal analysis. Complexes 2, 3, 5, 7, and 8 have been investigated as lactide polymerization initiators. The heterobimetallic alkoxyl 8 is highly active to yield high molecular weight (M(n) = 6.91 × 10(4)) polylactides with over 91% conversion at the lactide-to-initiator molar ratio of 2000.     

Formation of the imide [Ta(NMe2)3(μ-NSiMe3)]2 through an unprecedented α-SiMe3 abstraction by an amide ligand

Ta(NMe(2))(4)[N(SiMe(3))(2)] (1) undergoes the elimination of Me(3)Si-NMe(2) (2), converting the -N(SiMe(3))(2) ligand to the ═NSiMe(3) ligand, to give the imide "Ta(NMe(2))(3)(═NSiMe(3))" (3) observed as its dimer 4. CyN═C═NCy captures 3 to yield guanidinates Ta(NMe(2))(3-n)(═NSiMe(3))[CyNC(NMe(2))NCy](n) [n = 1 (5), 2 (6)]. The kinetic study of α-SiMe(3) abstraction in 1 gives ΔH(?) = 21.3(1.0) kcal/mol and ΔS(?) = -17(2) eu.     

Synthesis and structures of zirconium amide-iodide complexes

Zirconium amide-iodide complexes were synthesized for possible use as chemical vapor deposition precursors to zirconium nitride films. The series of six complexes Zr(NR(2))(4-n)I(n)(R = Me or Et; n = 1-3) was prepared by reacting ZrI(4) and Zr(NR(2))(4) in hot toluene. X-ray crystallographic analyses were performed for Zr(NMe(2))(3)I, Zr(NEt(2))(2)I(2), and Zr(NEt(2))I(3). In the solid state, Zr(NMe(2))(3)I and Zr(NEt(2))(2)I(2) are the discrete dimers [Zr(NMe(2))(2)I(mu-NMe(2))](2) and [Zr(NEt(2))(2)I(mu-I)](2), and Zr(NEt(2))I(3) is the polymer of dimers ([Zr(NEt(2))I(2)(mu-I)](2))(n). In solution, Zr(NEt(2))(3)I is proposed to be monomeric on the basis of NMR data and a molecular weight determination. The complex Zr(NEt(2))(3)I is the most promising precursor candidate because of its physical properties.     

Synthesis of triamidoamine ligands of the type (ArylNHCH(2)CH(2))(3)N and molybdenum and tungsten complexes that contain an [ArylNCH(2)CH(2))(3)N]3- ligand

Aryl bromides react with (H(2)NCH(2)CH(2))(3)N in a reaction catalyzed by Pd(2)(dba)(3) in the presence of BINAP and NaO-t-Bu to give the arylated derivatives (ArylNHCH(2)CH(2))(3)N [Aryl = C(6)H(5) (1a), 4-FC(6)H(4) (1b), 4-t-BuC(6)H(4) (1c), 3,5-Me(2)C(6)H(3) (1d), 3,5-Ph(2)C(6)H(3) (1e), 3,5-(4-t-BuC(6)H(4))(2)C(6)H(3) (1f), 2-MeC(6)H(4) (1g), 2,4,6-Me(3)C(6)H(2) (1h)]. Reactions between (ArNHCH(2)CH(2))(3)N (Ar = C(6)H(5), 4-FC(6)H(4), 3,5-Me(2)C(6)H(3), and 3,5-Ph(2)C(6)H(3)) and Mo(NMe(2))(4) in toluene at 70 degrees C lead to [(ArNHCH(2)CH(2))(3)N]Mo(NMe(2)) complexes in yields ranging from 64 to 96%. Dimethylamido species (Ar = 4-FC(6)H(4), 3,5-Me(2)C(6)H(3)) could be converted into paramagnetic [(ArNHCH(2)CH(2))(3)N]MoCl species by treating them with 2,6-lutidinium chloride in tetrahydrofuran (THF). The "direct reaction" between 1a-f and MoCl(4)(THF)(2) in THF followed by 3 equiv of MeMgCl yielded [(ArNHCH(2)CH(2))(3)N]MoCl species (3a-f) in high yield. If 4 equiv of LiMe instead of MeMgCl are employed in the direct reaction, then [(ArNHCH(2)CH(2))(3)N]MoMe species are formed. Tungsten species, [(ArNHCH(2)CH(2))(3)N]WCl, could be prepared by analogous "direct" methods. Cyclic voltammetric studies reveal that MoCl complexes become more difficult to reduce as the electron donating ability of the [ArylNCH(2)CH(2))(3)N]3- ligand increases, and the reductions become less reversible, consistent with ready loss of chloride from ([(ArNHCH(2)CH(2))(3)N]MoCl)(-). Tungsten complexes are more difficult to reduce, and reductions are irreversible on the CV time scale.     

Co-complexation of Lithium Gallates on the Titanium Molecular Oxide {[Ti(η(5)-C(5)Me(5))(μ-O)}(3)(μ(3)-CH)

Amide and lithium aryloxide gallates [Li(+){RGaPh(3)}(-)] (R = NMe(2), O-2,6-Me(2)C(6)H(3)) react with the μ(3)-alkylidyne oxoderivative ligand [{Ti(η(5)-C(5)Me(5))(μ-O)}(3)(μ(3)-CH)] (1) to afford the gallium-lithium-titanium cubane complexes [{Ph(3)Ga(μ-R)Li}{Ti(η(5)-C(5)Me(5))(μ-O)}(3)(μ(3)-CH)] [R = NMe(2) (3), O-2,6-Me(2)C(6)H(3) (4)]. The same complexes can be obtained by treatment of the [Ph(3)Ga(μ(3)-O)(3){Ti(η(5)-C(5)Me(5))}(3)(μ(3)-CH)] (2) adduct with the corresponding lithium amide or aryloxide, respectively. Complex 3 evolves with formation of 5 as a solvent-separated ion pair constituted by the lithium dicubane cationic species [Li{(μ(3)-O)(3)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-CH)}(2)](+) together with the anionic [(GaPh(3))(2)(μ-NMe(2))](-) unit. On the other hand, the reaction of 1 with Li(p-MeC(6)H(4)) and GaPh(3) leads to the complex [Li{(μ(3)-O)(3)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-CH)}(2)][GaLi(p-MeC(6)H(4))(2)Ph(3)] (6). X-ray diffraction studies were performed on 1, 2, 4, and 5, while trials to obtain crystals of 6 led to characterization of [Li{(μ(3)-O)(3)Ti(3)(η(5)-C(5)Me(5))(3)(μ(3)-CH)}(2)][PhLi(μ-C(6)H(5))(2)Ga(p-MeC(6)H(4))Ph] 6a.     

Non-heme iron(II) complexes containing tripodal tetradentate nitrogen ligands and their application in alkane oxidation catalysis

A series of iron(II) bis(triflate) complexes containing tripodal tetradentate nitrogen ligands with pyridine and dimethylamine donors of the type [N(CH(2)Pyr)(3-n)()(CH(2)CH(2)NMe(2))(n)] [n = 0 (tpa, 1), n = 1 (iso-bpmen, 3), n = 2 (Me(4)-benpa, 4), n = 3 (Me(6)-tren, 5)] and the linear tetradentate ligand [(CH(2)Pyr)MeN(CH(2)CH(2))NMe(CH(2)Pyr), (bpmen, 2)] has been prepared. The preferred coordination geometry of these complexes in the solid state and in CH(2)Cl(2) solution changes from six- to five-coordinate in the order from 1 to 5. In acetonitrile, the triflate ligands of all complexes are readily displaced by acetonitrile ligands. The complex [Fe(1)(CH(3)CN)(2)](2+) is essentially low spin at room temperature, whereas ligands with fewer pyridine donors increase the preference for high-spin Fe(II). Both the number of pyridine donors and the spin state of the metal center strongly affect the intensity of a characteristic MLCT band around 400 nm. The catalytic properties of the complexes for the oxidation of alkanes have been evaluated, using cyclohexane as the substrate. Complexes containing ligands 1-3 are more active and selective catalysts, possibly operating via a metal-based oxidation mechanism, whereas complexes containing ligands 4 and 5 give rise to Fenton-type chemistry.     

Synthesis and Characterization of a New Alkenyldecaborane and Alkenyl Monocarbon Carboranes

Decaborane(14) reacts with 1-(CH(3))(3)SiC&tbd1;CC(4)H(9) in the presence of dimethyl sulfide to give the new alkenyldecaborane 5-(S(CH(3))(2))-6-[(CH(3))(3)Si(C(4)H(9))C=CH]B(10)H(11) (I). Crystal data for 5-(S(CH(3))(2))-6-[(CH(3))(3)Si(C(4)H(9))C=CH]B(10)H(11): space group P2(1)/n, monoclinic, a = 9.471(1) ?, b = 13.947(3) ?, c = 17.678(3) ?, beta = 100.32(1) degrees. A total of 3366 unique reflections were collected over the range 2.0 degrees /= 3sigma(F(o)(2)) and were used in the final refinement. R(F)() = 0.083; R(w)(F)() = 0.094. The single-crystal X-ray structure of 5-(S(CH(3))(2))-6-[((CH(3))(3)Si)(2)C=CH]B(10)H(11) (A) is also reported. Crystal data for 5-(S(CH(3))(2))-6-[((CH(3))(3)Si)(2)C=CH]B(10)H(11): space group, P2(1)2(1)2(1), orthorhombic, a = 9.059 (3) ?, b = 12.193(4) ?, c = 21.431(3) ?. A total of 4836 unique reflections were collected over the range 6 degrees /= 3sigma(F(o)(2)) and were used in the final refinement. R(F)() = 0.052; R(w)(F)() = 0.059. The reactions of 5-(S(CH(3))(2))6-[(CH(3))(3)Si(C(4)H(9))C=CH]B(10)H(11) and 5-(S(CH(3))(2))6-[((CH(3))(3)Si)(2)C=CH]B(10)H(11) with a variety of alkyl isocyanides were investigated. All of the alkenyl monocarbon carboranes reported are the result of incorporation of the carbon atom from the isocyanide into the alkenyldecaborane framework and reduction of N&tbd1;C bond to a N-C single bond. The characterization of these compounds is based on (1)H and (11)B NMR data, IR spectroscopy, and mass spectrometry.     

Gallium oxide thin films from the AACVD of [Ga(NMe2)3]2 and donor functionalised alcohols

Thin films of Ga(2)O(3) have been produced from [Ga(NMe(2))(3)](2) and ROH (R = CH(2)CH(2)NMe(2), CH(CH(2)NMe(2))(2), CH(CH(3))CH(2)NMe(2), CH(2)CH(2)OMe and C(CH(3))(2)CH(2)OMe) by aerosol assisted chemical vapour deposition on glass. Transparent, unreflective films were obtained at a deposition temperature of 550 degrees C using toluene as solvent. The gallium oxide films were analyzed by Scanning electron microscopy (SEM), Raman spectroscopy, wavelength dispersive analysis of X-rays (WDX) and X-ray photoelectron spectroscopy (XPS). The gallium oxide films obtained were X-ray amorphous. Gas-sensing experiments indicated that the films showed an n-type response to ethanol at a variety of temperatures.     

Structural and catalytic studies of lithium complexes bearing pendant aminophenolate ligands

Lithium complexes bearing mono-anionic aminophenolate ligands are described. Reactions of ligand precursors HON(Me)Ph(OMe), HON(Me)Ph(SMe), HON(Me)C(OMe) or HON(Me)C(NMe2) [HON(Me)Ph(OMe) = (2-OMeC6H4CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)Ph(SMe)= (2-SMe-C6H4CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)C(OMe) = (MeOCH(2)CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2); HON(Me)C(NMe2) = (Me2NCH2CH2)N(Me)(CH2-2-HO-3,5-C6H2((t)Bu)2)] with 1.1-1.3 molar equivalents of (n)BuLi in diethyl ether solution afford (LiON(Me)Ph(OMe))(2) (3), (LiON(Me)Ph(SMe))2 (4), (LiON(Me)C(OMe))2 (5) and (LiON(Me)C(NMe2))2 (6) as dinuclear lithium complexes. The BnOH adduct of , (BnOH)(LiON(Me)C(OMe)) (7), was prepared from the reaction of and BnOH in diethyl ether solution. The molecular structures are reported for ligand precursor HON(Me)Ph(SMe) and compounds 3-5 and 7. These dinuclear lithium complexes show excellent catalytic activities toward the ring-opening polymerization of L-lactide in the presence of benzyl alcohol.     

Group-4 eta(1)-pyrrolyl complexes incorporating N,N-di(pyrrolyl-alpha-methyl)-N-methylamine

Syntheses and properties of group-4 complexes incorporating the tridentate, dianionic ligand N,N-(dipyrrolyl-alpha-methyl)-N-methylamine, dpma, have been investigated. Addition of 1 equiv of H(2)dpma to Ti(NMe(2))(4) and Zr(NMe(2))(4) results in transamination with 2 dimethylamides providing Ti(NMe(2))(2)(dpma) and Zr(NMe(2))(2)(NHMe(2))(dpma), respectively. Addition of 2 equiv of H(2)dpma to Zr(NMe(2))(4) and Hf(NMe(2))(4) results in production of the homoleptic complexes Zr(dpma)(2) and Hf(dpma)(2). Conversely, treatment of Ti(NMe(2))(4) with 2 equiv of H(2)dpma does not provide Ti(dpma)(2), which was available by addition of 2 Li(2)dpma to TiCl(4). The properties of the isostructural series M(dpma)(2) were investigated by single crystal X-ray diffraction, cyclic voltammetry, (14)N NMR, and other techniques. By (14)N NMR, it was found that the pyrrolyl resonance chemical shift changes approximately linearly with the electronegativity of the metal center, which was attributed to pi-interaction between the pyrrolyl nitrogen lone pair and the metal. Other complexes produced during this study include Ti(CH(2)SiMe(3))(NMe(2))(dpma), TiCl(2)(THF)(dpma), and Ti(OCH(2)CF(3))(2)(THF)(dpma). Two isomers for Ti(CH(2)SiMe(3))(NMe(2))(dpma) were isolated and characterized.     

Synthesis and structures of aluminium monohydride and chalcogenides bearing a bidentate [N,O] ligand

The aluminium monohydride (3-tBu-5-Me-2-(O)C(6)H(2)CH(2)-N-2,6-iPr(2)C(6)H(3))AlH(NMe(3))(2) was prepared by treatment of the bidentate salicylaldimine [3-tBu-5-Me-2-(OH)C(6)H(2)CH=N-2,6-iPr(2)C(6)H(3)](1) with a small excess of AlH(3).NMe(3) in high yield. Compound 2 reacted with sulfur and selenium respectively to afford the dimeric aluminium chalcogenide [(3-tBu-5-Me-2-(O)C(6)H(2)CH(2)-NH-2,6-iPr(2)C(6)H(3))Al(micro-E)](2)[E = S (3), E = Se (4)]. During the formation of 2 hydrogen migration from the aluminium centre to the ligand backbone occurred. A possible reaction mechanism for 3 and 4 is discussed and the molecular structures of compounds 2-4 were determined by X-ray structural analyses.