Free-standing PbSe nanocrystals, including quantum wires, multipods, quantum rods, quantum dots, and cubes, were produced in a colloidal solution in the presence of alkyl-diamine solvent at 10−117 °C. The morphology of the nanocrystals was governed by a solvent coordinating molecular template mechanism, which was further adjusted by the temperature and duration of the reaction. Crystalline wires with diameters of approximately 20 nm and lengths of 1−5 μm were formed at the lowest temperatures, while quantum rods (with an aspect ratio of ∼5) and cubes (with 100−500 nm edge) were formed at elevated temperatures.

Organoactinide complexes of the type Cp* 2 AnMe 2 (An ) Th, U) have been found to be efficient catalysts for the hydroamination of terminal alkynes with aliphatic primary amines. The chemoselectivity and regioselectivity of the reactions depend strongly on the nature of the catalyst and the nature of the amine and show no major dependence on the nature of the alkyne. The hydroamination reaction of the terminal alkynes with aliphatic primary amines catalyzed by the organouranium complexes produces the corresponding imines where the amine and the alkyne are regioselectively disposed in a syn-regiochemistry, whereas for similar reactions with the organothorium complex besides the methyl alkylated imine, dimeric and trimeric alkyne oligomers are also produced. For (TMS)CtCH and EtNH 2 both organoactinides produced the same imine compounds when the reaction is carried out in THF or toluene. In benzene, both imines E and Z (TMS)CH 2 CHNdEt are obtained, the earlier undergo a 1,3-silyl Brook sigmatropic rearrangement toward the enamine, whereas the latter remains unchanged. Mechanistic studies on the hydroamination of (TMS)CtCH and EtNH 2 promoted by the organouranium complex show that the first step in the catalytic reaction is the formation of the bis(amido) complex, found in equilibrium with the corresponding bisamido-amine complex, which loses an amine, yielding a uranium-imido complex. Insertion of the alkyne into the imido bond with subsequent amine protonolysis, isomerization, and product release comprise the primary steps in the catalytic cycle. The kinetic rate law was found to follow an inverse kinetic order in amine, a first order in complex, and a zero order in alkyne, with ∆H q ) 11.7(3) kcal mol -1 , ∆S q ) -44.5(8) eu. The turnoverlimiting step is the release of an amine from the bisamido complex yielding the imido complex.The key organoactinide intermediate for the intermolecular hydroamination reaction was found to be the corresponding actinide-imido complexes. For both actinides the complexes have been characterized, and for thorium the single-crystal X-ray diffraction was studied. A plausible mechanistic scenario is proposed for the hydroamination of terminal alkynes and aliphatic primary amines.3

Organoactinide complexes of the type Cp* 2 AcR 2 (Ac ) Th, U) catalyze the intermolecular hydroamination of terminal alkynes with aliphatic amines. The regioselectivity of the products can be tuned by the alkyne and the metal. Mechanistic studies shows that the ratelimiting step is the formation of an actinide imido complex. For thorium, the imido intermediate has been characterized by standard techniques, including X-ray diffraction.

The 1,1-dimethylheptyl (DMH) homologue of 7-hydroxy-delta 6-tetrahydrocannabinol (3) is the most potent cannabimimetic substance reported so far. Hydrogenation of 3 leads to a mixture of the epimers of 5'-(1,1-dimethylheptyl)-7-hydroxyhexahydrocannabinol or to either the equatorial (7) or to the axial epimer (8), depending on the catalysts and conditions used. Compound 7 discriminates for delta 1-THC (2) in pigeons (ED50 = 0.002 mg/kg, after 4.5 h), at the potency level of 3, and binds to the cannabinoid receptor with a KD of 45 pM, considerably lower than the Ki of 180 pM measured for compound 3 and the Ki of 2.0 nM measured for CP-55940 (1), a widely employed ligand. Tritiated 7 was used as a novel probe for the cannabinoid receptor.

The synthesis and structural X-ray diffraction studies for some benzamidinate ligations and several group 4 benzamidinate complexes are presented. The use of the cis-octahedral C(2)-symmetry compounds was studied to shed light on the conceptual applicability of these complexes as potential catalysts for the stereoregular polymerization of propylene. We demonstrate that the stereoregular polymerization of propylene catalyzed by early-transition metal octahedral benzamidinate complexes, activated with either MAO or B(C(6)F(5))(3) as cocatalysts, can be modulated by pressure (from atactic to isotactic through elastomers). The different effects in the polymerization process such as the nature of solvent or cocatalyst, temperature, pressure, molar ratio catalyst:cocatalyst, and the relationship between the symmetry of the complex and the polymer microstructure have been investigated. When the complex [4-CH(3)-C(6)H(4)C(NTMS)(2)](2)ZrMe(2) (9) was activated with MAO, it was found to be a good catalyst for the polymerization of propylene, at atmospheric pressure, producing an oily polymer resembling an atactic polypropylene. Being activated with B(C(6)F(5))(3), complex 9 produces a highly isotactic (mmmm = 98%) product. Likewise, when the polymerization of propylene was performed with complex 9 and MAO at high pressure (liquid propylene), a highly stereoregular polymer was also obtained. Larger activities and stereoregularities were achieved by performing the reaction in CH(2)Cl(2) as compared to toluene. Contrary to complex 9, at atmospheric pressure the complex [4-CH(3)-C(6)H(4)C(NTMS)(2)](2)TiMe(2) (10) is not active either in CH(2)Cl(2) or in toluene. At high pressure, complex 10 produces elastomeric polypropylene. Activities of the isolobal complexes [C(6)H(4)C(NTMS)(2)](2)ZrMe(2) (11) and [C(6)H(4)C(NTMS)(2)](2)TiMe(2) (12) were found to be larger than those of complexes 9 and 10, respectively. Contrary to the structures of the elastomeric polypropylenes described in the literature, the obtained elastomers are characterized by frequent alternation of the isotactic domains with stereodefects. The stereoregular errors are formed by the intramolecular epimerization of the growing chain at the last inserted unit. The epimerization reaction was corroborated through the isomerization of alkenes.