The convenient five-coordinate starting materials, Salen((t)Bu)AlCl (Salen((t)Bu) = N,N'-alkylene (or arylene) bis (3,5-di-tert-butyl-2-hydroxybenzylideneamine) (1-4) can be used in a wide range of reactions to form five-coordinate aluminum compounds. Herein, these reagents were used to produce new five-coordinate azides, LAlN(3) (L = Salen((t)Bu) (5), Salpen((t)Bu) (6), and Salomphen((t)Bu) (7)) through trimethylsilylhalide elimination. The decomposition of the azides produce first hydroxide (LAlOH (L = Salen((t)Bu) (8)) and, subsequently in the presence of chlorotrimethylsilane, the siloxide compounds, LAlOSiMe(3) (L = Salen((t)Bu) (9), Salpen((t)Bu) (10), and Salomphen((t)Bu) (11)). Alkane elimination reactions may also be used to access this type of compound as evidenced by the formation of Salomphen((t)Bu)AlOSiPh(3) (12). Additionally, the first structurally characterized five-coordinate monomeric amide, Salcen((t)Bu)AlN(SiMe(3))(2) (13), can prepared by a salt elimination utilizing Salcen((t)Bu)AlCl (4). The compounds were characterized by spectroscopic methods ((1)H and (27)Al NMR, MS, and IR) and, in the case of 2 (Salpen((t)Bu)AlCl), 3 (Salomphen((t)Bu)AlCl) 9, 11, 12, and 13, by X-ray analysis. Several of the compounds were explored as potential catalysts for the living polymerization of propylene oxide.

Three new N-heterocyclic-silazane compounds, 1a-c, were prepared and employed as bidentate ligands to ruthenium, resulting in a series of [Ru(H){(κ-Si,N-(SiMe2-N-heterocycle)}3] complexes (3a-c) featuring the same RuSi3H motif. Detailed structural characterization of the RuSi3H complexes with X-ray diffraction, and in the case of triazabicyclo complex [Ru(H){κ-Si,N-(SiMe2)(C7H12N3)}3] (3a), neutron diffraction, enabled a reliable description of the molecular geometry. The hydride ligand of (3a) is located closer to two of the silicon atoms than it is to the third. Such a geometry differs from that of the previously reported complex [Ru(H){(κ-Si,N-(SiMe2)N(SiMe2H)(C5H4N)}3] (3d), also characterized by neutron diffraction, where the hydride was found to be equidistant from all three silicon atoms. A DFT study revealed that the symmetric and less regular isomers are essentially degenerate. Information on the dynamics and on the Ru···H···Si interactions was gained from multinuclear solid-state ((1)H wPMLG, (29)Si CP MAS, and 2D (1)H-(29)Si dipolar HETCOR experiments) and solution NMR studies. The corresponding intermediate complexes, [Ru{κ-Si,N-(SiMe2-N-heterocycle)}(η(4)-C8H12)(η(3)-C8H11)] (2a-c), involving a single silazane ligand were isolated and characterized by multinuclear NMR and X-ray diffraction. Protonation of the RuSi3H complexes was also studied. Reaction of 3a with NH4PF6 gave rise to [Ru(H)(η(2)-H -SiMe2)κ-N-(C7H12N3){κ-Si,N-(SiMe2)(C7H12N3)}2](+)[PF6](-)(4aPF6) which was isolated and characterized by NMR spectroscopy, X-ray crystallography, and DFT studies. The nature of the Si-H interactions in this silazane series was analyzed in detail.

The reactions of the complexes [(dcype)NiH]2, 1, [(dippe)NiH]2, 2, and [(dtbpe)NiH]2, 3, with a mixture of BEt3 and Super-Hydride (LiHBEt3) afforded sigma-borane nickel(0) compounds of the type [(dcype)Ni(sigma-HBEt2)], 4, [(dippe)Ni(sigma-HBEt2)], 5, [(dtbpe)Ni(sigma-HBEt2)], 6, respectively, with the concomitant formation in each case of [(dcype)2Ni2)(H)3][BEt4], 7, [(dippe)2Ni2(H)3][BEt4], 8 and [(dtbpe)2Ni2(H)3][BEt4], 9, respectively. X-ray crystal structures are reported for 4 and 8. The reaction of BEt3 and LiHBEt3 was also reviewed in detail.

No abstract

A potentially tridentate ligand, Phensal(tBu)H 3 , was prepared by the condensation of 1 equiv of phenylenediamine with 3,5-di-tert-butylsalicylaldehyde. When 1 equiv of this new ligand is added to AlMe 3 , [[Phensal(tBu)HAlMe]] 2 (1) results. In contrast, this reaction with GaMe 3 produces [Phensal(tBu)H 2 ]GaMe 2 (2). When 1 or 2 equiv of Phensal(tBu)H 3 is combined with Et 2 AlCl, the complex [Phensal(tBu)] 2 AlCl (3) forms. However the same reaction with Me 2 GaCl leads to [Phensal(tBu)H 2 ]Ga(Me)Cl (4). A cationic complex, {[Phensal(tBu)] 2 Al} + Cl -(5), is formed when 3 is dissolved in MeOH. The MeOH apparently mediates the formation of the cation but does not coordinate the cationic metal. When the solvent is removed, 5 reverts back to neutral 3. When 3 is combined with GaCl 3 in toluene, another cationic complex, {[Phensal(tBu)H 2 ] 2 Al} + GaCl 4 -(6), is formed. In a similar manner, {[Phensal(tBu)H 2 ] 2 Al} + Me 2 AlCl 2 -(7) is formed by adding Me 2 AlCl to 3. The compounds were characterized by mp, elemental analyses, IR, 1 H and 27 Al NMR, and in the case of 2, 5, and 6 single-crystal X-ray analysis.Supporting Information Available: Crystallographic data for compounds 2, 5, and 6, which includes full tables of bond lengths and angles, full atom-labeled ORTEP views, and unit cell views. This material is available free of charge via the Internet at http://pubs.acs.org. Observed and calculated structure factor tables are available upon request. This data may also be obtained at the Cambridge Crystallographic Database (CCDC 139436, 139437, 139438).

The pyrazolato complexes [(Me(2)pz)(THF)Li] (1), [((t)Bu(2)pz)Li](4) (2), [((t)Bu(2)pzH)((t)()Bu(2)pz)Li](2) (2a), [(Me(2)pz)Na] (3), [((t)Bu(2)pz)Na](4), [((t)Bu(2)pz)(6)(OH)Na(7)] (4a), [((t)Bu(2)pz)(18-crown-6)Na] (4b), and [((t)Bu(2)pz)K] (5) were synthesized by metalation reactions between R(2)pzH (R = Me, (t)()Bu) and alkyllithium, elemental sodium, or potassium. All the complexes were characterized by spectroscopic methods and microanalysis, and in addition, the crystal structures of 2, 2a, 3, 4a, 4b, and 5 were obtained by single-crystal X-ray diffraction. They show monomeric, dimeric, cluster, and 1D chain structures in the solid state. Ab initio calculations on the structure and stabilities of the monomeric pzM complexes were performed at the MP2 level of theory showing good agreement with the coordination preferences of the pyrazolato ligand to a particular alkali ion.

No abstract

Reaction of a phosphinobenzylsilane compound with ruthenium complexes leads to C-H and/or Si-H activation. The new complex Ru{eta(2)-H-SiMe2CH(o-C(6)H(4))PPh2}2 (5) was isolated and X-ray, NMR and DFT studies reveal that 5 displays two agostic Si-H interactions and two carbon-metallated bonds.