Synthesis and structural characterization of aluminum iminophosphonamide complexes.

Monoanionic iminophosphonamide ligands have a N-P-N linkage and undergo four-membered ring N,N-ligand formation when treated with aluminum compounds. The reaction of LLi (L = [Ph(2)P(NSiMe(3))(2)]) with equivalent amounts of AlCl(3) and AlMeCl(2) in toluene afforded LAlCl(2) (3) and LAlClMe (4), respectively. L(2)AlH (5), LAlEt(2) (6), and LAl(NMe(2))(2) (7) respectively were prepared by the reaction of LH with AlH(3) x NMe(3), AlEt(3), and Al(NMe(2))(3) in n-hexane. Subsequently compounds 3-7 were characterized by elemental analysis, (1)H, (13)C, and (31)P NMR spectroscopy and X-ray crystallographic studies (for 3, 4, 5, and 7).

A germanium(II) hydride as an effective reagent for hydrogermylation reactions.

Herein we report on the reactivity of the stable germanium(II) hydride LGeH (L = CH{(CMe)(2,6-iPr(2)C(6)H(3)N)}(2)) (2), which contains a low-valent germanium atom. 2 is prepared from the corresponding germanium(II) chloride LGeCl (1) using H(3)Al x NMe(3) or K[HB(iBu)(3)] in toluene. The reaction of 2 with carbon dioxide in toluene at room temperature affords a germanium(II) ester of formic acid, LGe-O-C(O)H (3), which is formed by insertion of the carbon dioxide into the germylene hydrogen bond. 2 also reacts with alkynes at room temperature to give the first germanium(II)-substituted alkenes (4, 5, and 6). These two reaction types have in common the fact that the hydrogen and germylene from LGeH are transferred to an unsaturated bond: the carbon-oxygen double bond (C=O) in the former case and the carbon-carbon triple bond (C[triple bond]C) in the latter. Moreover, the reaction of 2 with elemental sulfur in toluene at room temperature leads to the germanium dithiocarboxylic acid analogue LGe(S)SH (7). Compound 7 is formed by the unprecedented insertion of elemental sulfur into the germylene hydrogen bond and oxidative addition of elemental sulfur to the germanium(II) atom. This leads to the formal conversion of the GeH hydride to a SH proton. Compounds 3-7 were investigated by microanalysis, multinuclear NMR spectroscopy, and single-crystal X-ray structural analyses.

Functionalization of aminophosphanes: synthesis and X-ray crystal structure of novel dilithium and trilithium complexes containing silicon-fused heteronuclear SiN2PLi five-membered rings.

A first structurally characterized primary aminophosphane (Ar 2PNH 2 ( 2); Ar = 2,4,6- iPr 3C 6H 2) that is a stable solid at room temperature without decomposition by self-condensation is reported. Reactions of N-phosphanyllithium amide ( tBu 2PNHLi ( 3)) with Me 2SiCl 2 and MeSiCl 3 in Et 2O result in the formation of Me 2Si(NHP tBu 2) 2 ( 4) and MeSi(NHP tBu 2) 3 ( 5), respectively. Subsequent treatment of 4 and 5 with 2 and 3 equiv of nBuLi gave the dilithium ( 6) and trilithium ( 7) complexes, respectively. Further treatment of 5 with 3 equiv of AlMe 3 yielded the trialuminum complex MeSi[N(AlMe 2)P tBu 2] 3 ( 8). These three complexes were investigated by microanalysis and multinuclear NMR spectroscopy. The dilithium complex [Me 2Si(NLiP tBu 2) 2.3THF] ( 6) and the trilithium complex [MeSi(NLiP tBu 2) 3.3Et 2O] ( 7) were further characterized by single-crystal X-ray structural analysis.

Structural and variable-temperature NMR studies of 9-diisopropylphosphanylanthracenes and 9,10-bis(diisopropylphosphanyl)anthracenes and their oxidation products.

The diisopropylphosphanyl-substituted anthracenes i-Pr2P(C14H9) (1a), i-Pr2P(C14H8)Br (2a), and (i-Pr2P)2(C14H8) (3a) and some of their oxidation products were prepared from 9-bromoanthracene and 9,10-dibromoanthracene, respectively. Low-temperature (1)H NMR spectra of the 9-monophosphanyl-substituted anthracenes 1a and 2a are in accordance with a staggered conformer, while above room temperature dynamic processes occur. The low-temperature NMR spectrum of the 9,10-diphosphanylanthracene 3a indicates the presence of two different rotational isomers. The rotational barrier for 1a was determined from variable-temperature (1)H NMR spectra to be 56 kJ mol(-1) (DeltaG(298K)). The crystal structure determinations show the solid-state conformers to be consistent with the prevailing conformer at low temperature.

Oxygen-bridged hybrid metallocene-nonmetallocene polymetallic catalysts of group 4 metals for bimodal activity in olefin polymerization: synthesis, characterization, and theoretical investigation.

This article describes the syntheses of two covalently linked oxygen-bridged hybrid metallocene-nonmetallocene polymetallic catalysts bearing two different catalytically active group 4 metals. The reactions of Cp*2(Me)Zr(OH) (2) with Ti(NMe2)4 and Hf(NMe2)4 led to the formation of a heterobimetallic compound Cp*2(Me)Zr(micro-O)Ti(NMe2)3 (7) and a trimetallic derivative Cp*2(Me)Zr(micro-O)Hf(NMe2)2(micro-O)Zr(Me)Cp*2 (9), respectively, under the elimination of Me2NH. The crystal data confirm the molecular structures of 7 and 9, which crystallize in the space groups P and P21/n, respectively. 9 is the first example of a crystallographically characterized heterotrimetallic complex having a Zr-O-Hf-O-Zr core. 7 bearing two active catalytic centers, namely, zirconium and titanium, exhibits bimodal activity in olefin polymerization when activated with methylalumoxane (MAO). It produces polyethylene largely controlled by the zirconium center, and polystyrene seems to be formed predominantly by the titanium center. DFT calculations were performed on the supposed cationic intermediates, revealing that a cation generated on the titanium center is sterically more accessible for monomer binding, though it is energetically less-favorable than that generated on the zirconium center.