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ABSTRACT: Monomeric iminoalane: A donor-stabilized monomeric iminoalane was prepared by the reaction of 1 with an N-heterocyclic carbene. The X-ray structure exhibits a very short AlN bond of 1.705(4) Å, which suggests multiple-bond character. Treatment of the iminoalane with phenyl acetylene, aniline, and carbon monoxide resulted in addition reactions to the formal AlN bond, thus indicating that the AlN multiple bond is highly reactive.
Chemistry 11/2012; · 5.93 Impact Factor
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ABSTRACT: Top cat: [(NHC)Yb{N(SiMe(3) )(2) }(2) ] adducts (NHC=N-heterocyclic carbene) are efficient catalysts for catalytic cross-dehydrogenative coupling of silanes with a range of primary and secondary amines to yield silylamines in high yields (82-100 %) under mild reaction conditions. The catalytic activity and selectivity of the rare-earth-metal silylamides are modulated by altering the steric bulk of the NHC.
Angewandte Chemie International Edition 10/2012; 51(44):11141-4. · 13.45 Impact Factor
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ABSTRACT: A series of pentaaryl-substituted diazaboroles have been prepared for the first time by a novel strategy based on the C-C double bond formation from imidoylstannane reagents in the presence of dibromophenylboranes. The aryl substituents on the 4,5-position of the planar C(2)N(2)B core have substantial effects on their electronic structures. All the new diazaboroles are luminescent both in solution and in the solid state. DFT calculations indicate the 4,5-C-aryl substituents have significant contributions to the LUMOs.
Journal of the American Chemical Society 08/2012; 134(36):14666-9. · 9.91 Impact Factor
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ABSTRACT: Reactions of the aminochlorosilane RSiHCl(2) and disilane R(2)Si(2)HCl(3) (R = (2,6-iPr(2)C(6)H(3))(SiMe(3))N) with an excess of 1,3-bis(tert-butyl)imidazol-2-ylidene resulted in the silylation of the NHC while reaction with the less hindered 1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene yielded an NHC-stabilized aminochlorosilylene.
Dalton Transactions 11/2011; 40(44):11937-40. · 3.84 Impact Factor
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ABSTRACT: 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.
Inorganic Chemistry 08/2011; 50(16):7453-9. · 4.60 Impact Factor
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ABSTRACT: Tossing aldehydes into the ring: The reaction of a silacyclopentadienylidene with aldehydes leads to CO bond cleavage with the formation of base-stabilized silanones and cyclopropanation of the adjacent CC bond, followed by silole ring expansion to give silicon analogues of cyclohexadienones.
Chemistry 06/2011; 17(32):8803-6. · 5.93 Impact Factor
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Chemistry - An Asian Journal 03/2011; 6(5):1138-41. · 4.50 Impact Factor
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Angewandte Chemie International Edition 03/2011; 50(12):2816-9. · 13.45 Impact Factor
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Angewandte Chemie International Edition 10/2010; 49(47):8958-61. · 13.45 Impact Factor
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ABSTRACT: Stable compounds with a boron-chalcogen (S or Se) valence double bond have been prepared via sequences involving insertion of the chalcogen into a B-H bond and subsequent hydrogen migration. X-ray diffraction studies and density functional theory calculations on the resulting compounds provide convincing evidence for the boron-chalcogen multiple bonding.
Journal of the American Chemical Society 08/2010; 132(32):10998-9. · 9.91 Impact Factor
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Applied Organometallic Chemistry 12/2009; 24(2):82 - 85. · 2.06 Impact Factor
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ABSTRACT: The super azaphosphaallyl free anion and its monomeric potassium and thallium complexes stabilized by M-arene interactions were synthesized and structurally characterized.
Dalton Transactions 11/2009; · 3.84 Impact Factor
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ABSTRACT: Reaction of cyclic diaminochlorosilanes with 1,3-bis(tert-butyl)imidazol-2-ylidene resulted in the facile formation of the corresponding stable and transient diaminosilylenes. This novel dehydrochlorination route could be applied for the generation of four- and five-membered N-heterocyclic silylenes with a range of different substituents under very mild conditions. Activation of an olefinic C−H bond and reduction of a cyclic diaminochlorosilane have been observed for these new transient silylenes.
09/2009;
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ABSTRACT: Two N-aryl substituted five-membered heterocyclic silylenes and their nickel complexes have been isolated and structurally characterized.
Dalton Transactions 08/2009; · 3.84 Impact Factor
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ABSTRACT: The synthesis and structural characterization of monomeric and linear polymeric divalent samarium complexes as well as their related trivalent species supported by an (imino)pyrrolide ligand are described. The divalent samarium 2-(N-arylamino)pyrrolide complex [NN]2Sm(THF)2 (1) was prepared by the reaction of SmI2(THF)2 with 2 equiv of [NN]K ([NN] = [2-(2,6-iPr2C6H3NCH)-5-tBuC4H2N]−) in THF. Upon treatment of 1 with dry oxygen, the oxo-bridged dimer [NN]2Sm(μ-O)Sm[NN]2 (2) was generated. Reaction of [NN]2SmCH2SiMe3 (3) with 3 equiv of AlEt3 in n-hexane gave the samarium aluminate [NN]2Sm(μ-Et)2AlEt2 (4). Reduction of 4 with potassium in toluene yielded the linear polymeric species {[NN]2SmAlEt4K(C7H8)}n (5). Compounds 1, 2, 4, and 5 have been characterized by X-ray single-crystal analysis. 5 features a linear polymeric structure, in which the potassium ion links the neighboring monomeric samarium moieties via η2 and η5 coordination to the pyrrolide rings in the two different units, with one toluene molecule and one of the ethyl groups of the [AlEt4] anion being also η2 coordinated to the potassium to complete its coordination sphere.
05/2009;
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ABSTRACT: The synthesis and characterization of the two homoleptic mononuclear nickel complexes (2,6-Dipp2C6H3NH)2Ni ( 1) and [2-C(H)NDippC6H4NH] 2Ni (2) (Dipp = 2,6-Pr(i)2C6H3) are described. 1 is formally two-coordinate and adopts a strictly linear geometry, while 2 features a slightly distorted square-planar geometry. Electrochemistry of 1 and 2 shows that they can be reduced to the corresponding nickel(I) species and oxidized to the corresponding nickel(III) species reversibly or quasi-reversibly. A solid-state magnetic measurement (mu(eff )= 2.79 mu(B)) for paramagnetic 1 indicates the presence of two unpaired electrons on the nickel center.
Inorganic Chemistry 06/2008; 47(9):3468-70. · 4.60 Impact Factor
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ABSTRACT: Nickel complexes incorporating sulfonamido-imine ligands [o-C(H)NDipp-C6H4NSO2(Ar)]− (Dipp = 2,6-iPr2C6H3; L1 where Ar = 2,4,6-Me3C6H2, L2 where Ar = 4-MeC6H4, L3 where Ar = 4-O2NC6H4) were synthesized and characterized. Reaction of L1Li with trans-[Ni(Cl)(Ph)(PPh3)2], NiBr2(THF)1.5, and NiCl2(Py)4 resulted in the formation of the nickel(I) complex L1Ni(PPh3) (1) and the four-coordinate nickel halides L1Ni(Br)(THF) (2) and L1Ni(Cl)(Py) (3), respectively. In contrast, reactions of less hindered L2Li and L3Li with NiBr2(DME) yielded the bis(sulfonamido-imine)nickel complexes (L2)2Ni (4) and (L3)2Ni (5). Alkylation of 2 with LiCH2SiMe3 afforded the neutral nickel alkyl L1Ni(CH2SiMe3) (6). The molecular structures of 1–5 have been determined by X-ray single-crystal analysis. DFT calculations revealed that 6 adopts a distorted square-planar geometry with one of the oxygen atoms of the sulfonyl group being bound to the nickel center.
03/2008;
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ABSTRACT: Reaction of the imine ArNC(SiMe3)2 (1; Ar = 2,6-iPr2C6H3) with LiAlH4 in THF resulted in the formation of the dimeric hydroaluminate [(THF)2LiH3AlL]2 (2; L = [ArNCH(SiMe3)2]−). 2 reacted with CH3I to give the monomeric aluminum dihydride LAlH2(THF) (3), which can be converted to the diiodide LAlI2(THF) (4) upon treatment with 2 equiv of Me3SiI. The quasi two-coordinate lithium amide Li(OEt2)L (8) with an intramolecular CH−Li interaction was obtained by the deprotonation of the corresponding amine LH (5) generated from hydrolysis of 2. Reduction of 1 with lithium in THF resulted in the first structurally characterized monomeric C−N vicinal dianion, Li2(THF)3[ArNC(SiMe3)2] (6), and the monomeric lithium amide Li(THF)2L (7).
01/2008;
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ABSTRACT: Hydrolysis and alcoholysis of the cyclic aluminum acyl LAl[C(O)C(SiMe3)C(SiMe3)] (1; L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3) resulted in the formation of the cyclopropenylaluminum derivative LAl{[C3(SiMe3)2]C(O)C(SiMe3)C(SiMe3)} (2) with the elimination of aluminum hydroxides LAlOH(OR) (R = H, Et, tBu).
02/2007;
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ABSTRACT: The reaction of H2C[(CBut)2(NAr)2] (Ar = 2,6-Pri2C6H3) with AlEt3 in refluxing toluene gave HC[(CBut)2(NAr)2]AlEt2 (1) in high yield. Treatment of 1 with 2 equiv of iodine in toluene yielded HC[(CBut)2(NAr)2]AlI2 (2). Reduction of 2 with potassium resulted in the formation of the tert-butyl-substituted β-diketiminato aluminum(I) compound HC[(CBut)2(NAr)2]Al (3). Reactions of 3 with isocyanides, H2O, and a bulky terphenyl azide were investigated. 3 reacted with 2 equiv of CNAr to give two C−C coupling products: in dilute solution, the C−C coupling of two CNAr molecules was followed by the C−H activation of one of the CHMe2 groups on the Ar ring of CNAr, while in concentrated solution or in the presence of an excess of the isocyanide, the coupling was accompanied by cleavage of one of the C−N bonds of the ligand backbone. Reaction of 3 with the bulky azide 2,6-Ar2C6H3N3 yielded the C−H activation product 6. Hydrolysis of 3 in toluene afforded a hydroxyaluminum hydride. Compounds 1 and 3−5 were characterized by X-ray single-crystal analysis.
01/2007;
