The experimental electron density study of Ti(C(5)H(4)Me)(2)[(CH(2))(2)CMe(2)] provides direct evidence for the presence of (C-C)-->Ti agostic interactions. In accord with the model of Scherer and McGrady, the C(alpha)-C(beta) bond densities no longer show cylindrical symmetry in the vicinity of the Ti atom and differ markedly from those of the other C-C bonds. At the points along the C(alpha)-C(beta) bond where the deviation is maximal the electron density is elongated toward the metal center. The distortion is supported by parallel theoretical calculations. A calculation on an Mo complex in which the agostic interaction is absent supports the Scherer and McGrady criterion for agostic interactions. Despite the formal d(0) electron configuration for this Ti(IV) species, a significant nonzero population is observed for the d orbitals, the d orbital population is largest for the d(xy) orbital, the lobes of which point toward the two C(alpha) atoms. Of the three different basis sets for the Ti atom used in theoretical calculations with the B3LYP functional, only the 6-311++G** set for Ti agrees well with the experimental charge density distribution in the Ti-(C(alpha)-C(beta))(2) plane.
5 ). The reaction of the tetramer with a mixture of 2-methyl-4-phenylpenta(-1,3-or -2,4-)dienes led to the Pdl = 2-Me-4-PhC 5 H 5 complex. In contrast, the reaction of the tetramer with 3-phenylpenta-1,3-diene led to simple incorporation of the η 4 -diene ligand. Structural confirmation of the formulations of the four η 5 -pentadienyl complexes has been achieved, allowing for a number of comparisons to be made regarding the structural effects of phenyl substitution on the (1,5), (2,4) and 3 positions of the open dienyl ligand.
Iron aerogels possessing high surface areas (∼422 m2 g−1) were synthesized and characterized. Catalytic activity of iron aerogels doped with 1% and 2% palladium (Pd) by weight in the water gas shift (WGS) reaction was investigated. Iron aerogels were synthesized using propylene oxide as the proton scavenger for the initiation of hydrolysis and polycondensation of iron(III) chloride hexahydrate precursor. Palladium was doped onto iron aerogels by the gas-phase incorporation (GPI) technique using (η3-allyl)(η5-cyclopentadienyl)palladium as the volatile organometallic Pd precursor. Water gas shift catalytic activities were evaluated in a six-channel fixed-bed reactor at atmospheric pressure and reaction temperatures ranging from 150 to 350 °C. Both 1% and 2% Pd iron aerogels showed good WGS activity and conversion of CO compared to undoped iron aerogels. The WGS activity of 2% Pd iron aerogel was higher by 50% than that of 1% Pd incorporated iron aerogel.
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