Titanium-Catalyzed Polymerization of a Lewis Base-Stabilized Phosphinoborane.

The reaction of the Lewis base-stabilized phosphinoborane monomer tBuHPBH NMe (2 a) with catalytic amounts of bis(η :η -adamantylidenepentafulvene)titanium (1) provides a convenient new route to the polyphosphinoborane [tBuPH-BH ] (3 a). This method offers access to high molar mass materials under mild conditions and with short reaction times (20 °C, 1 h in toluene). It represents an unprecedented example of a transition metal-mediated polymerization of a Lewis base-stabilized Group 13/15 compound.

Molecular structures of a series of substituted bis(η-cyclopentadienyl)titanium dihalides CpTiX [X = F, Cl, Br and I; R = CHPh, CH(p-Tol) and adamantyl].

Metallocene dihalides and derivatives thereof are of great interest as precursors for catalysts in polymerization reactions, as antitumor agents and, due to their increased stability, as suitable starting materials in salt metathesis reactions and the generation of metallocene fragments. We report the synthesis and structural characterization of a series of eleven substituted bis(η-cyclopentadienyl)titanium dihalides, namely bis[η-1-(diphenylmethyl)cyclopentadienyl]difluoridotitanium(IV), [Ti(CH)F], bis{η-1-[bis(4-methylphenyl)methyl]cyclopentadienyl}difluoridotitanium(IV), [Ti(CH)F], and bis{η-1-[bis(adamantan-2-yl)methyl]cyclopentadienyl}difluoridotitanium(IV), [Ti(CH)F], together with the bromide and iodide analogues, and the chloride analogues of the diphenylmethyl and adamantyl complexes. These eleven complexes were prepared by the reaction of the corresponding bis(η:η-pentafulvene)titanium complexes with different hydrogen halides (Cl, Br and I).

Formation of Binuclear Zigzag Hexapentaene Titanium Complexes via a Titanacumulene [Ti=C=C=CH ] Intermediate.

The reaction of bis(η :η -pentafulvene)titanium complexes with an allylidenephosphorylide Ph P=C(H)- C(H)=CH leads to binuclear zigzag hexapentaene titanium complexes (Ti2a, Ti2b). The formation of the central C H unit can be described as a spontaneous double C-H bond activation process, leading to an R P=C=C=CH intermediate, as a synthon for a titanabutatriene fragment [(Cp ) Ti=C=C=CH ] (R: 2-adamantyl, CH(p-tol) ). In a subsequent dimerization Ti2a and Ti2b are formed, proofed by single-crystal X-ray diffraction and NMR measurements.

Crystal structures of titanium-aluminium and -gallium complexes bearing two -CH units.

The isotypic crystal structures of two titanocene complexes containing an Me unit ( Al, Ga; Me = meth-yl) with two -coordinating methyl groups, namely [μ-1(η)-(adamantan-1-yl-2κ)cycylo-penta-dien-yl]di-μ-methyl-methyl-2κ-[1(η)-penta-methyl-cyclo-penta-dien-yl]aluminiumtitanium(III), [AlTi(CH)(CH)(CH)], and [μ-1(η)-(adamantan-1-yl-2κ)cycylo-penta-dien-yl]di-μ-methyl-methyl-2κ-[1(η)-penta-methyl-cyclo-penta-dien-yl]galliumtitanium(III), [GaTi(CH)(CH)(CH)], are reported. Reacting a dinuclear nitro-gen-bridged low-valent titanium(III) complex with the Lewis acids AlMe or GaMe results in the loss of mol-ecular di-nitro-gen and the formation of two monomeric titanocene(III) fragments bearing two -bridging methyl groups. Single crystal X-ray diffraction reveals the formation of a new -C bond involving the penta-fulvene ligand while the bridging and terminal methyl groups remain intact.

Epiphysiolysis of the femoral neck due to closed reduction of an adolescent hip dislocation with a 4-year follow-up: a case report and review of the literature.

This case study discusses a 13-year-old girl diagnosed with a displaced Salter Harris II fracture of the proximal femoral epiphysis post reduction of a dislocated hip. Radiographs before reduction revealed a small fracture of the inferomedial femoral head. This, however, did not induce concern before reduction.