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This article examines the relationship between Research & Development (R&D) funding and the production of knowledge by academic chemists. Using articles published, either raw counts or adjusted for quality, we find a strong, positive causal effect of funding on knowledge production. This effect is similar across subsets of universities, suggesting a relatively efficient allocation of R&D funds. Finally, we document a rapid acceleration in the rate at which chemical knowledge was produced in the late 1990s and early 2000s relative to the financial and human resources devoted to its production.
Assuntos
Química/economia , Eficiência , Apoio Financeiro , Pesquisa/economiaRESUMO
The design and synthesis of a new family of tridentate Schiff base ligands for use in octahedral molecular templates has been successfully demonstrated. As anticipated, two molecules of the ligand, 2,6-pyridinedicarboxaldhydebis(p-hydroxyphenylimine), coordinate equatorially to six-coordinate octahedral metal ions to give orthogonally oriented molecular turns around the anchoring metal ion. This new template offers the advantages that (1) syntheses of the ligand and its complexes are straightforward, giving high yields in simple, one-pot reactions, and (2) structural variations are easily accomplished. X-ray structural analysis has shown that the ligand will only function as a turn when its spatial organization is controlled by coordination to a metal ion. Upon chelation, the phenolic groups are directed across and beyond the metal ion center, and, unlike earlier ligands of this general type which lacked reactive moieties, substitution reactions may be carried out at the free phenolic groups of the octahedral complex. These reactions remain to be optimized in order to achieve the long-term goal of proving their value as synthons for interlocked molecules.
RESUMO
Resonance Raman spectra of the cubic metal-halide complexes having the general formula [M(6)X(8)Y(6)](2)(-) (M = Mo or W; X, Y = Cl, Br, or I) are reported. The three totally symmetric fundamental vibrations of these complexes are identified. The extensive mixing of the symmetry coordinates that compose the symmetric normal modes expected in these systems is not observed. Instead the "group-frequency" approximation is valid. Furthermore, the force constants of both the apical and face-bridging metal-halide bonds are insensitive to the identity of either the metal or the halide. Raman spectra of related complexes with methoxy and benzenethiol groups as ligands are reported along with the structural data for [Mo(6)Cl(8)(SPh)(6)][NBu(4)](2). Crystal data for [Mo(6)Cl(8)(SPh)(6)][NBu(4)](2) at -156 degrees C: monoclinic space group P2(1)/c; a = 12.588(3), b = 17.471(5), c = 20.646(2) Å; beta = 118.53(1) degrees, V = 3223.4 Å(3); d(calcd) = 1.664 g cm(-)(3); Z = 2.
RESUMO
Ruthenium benzylidene metathesis catalysts react with 2,3-dicarbomethoxymethylene-cyclopropane, eliminating styrene and dimethyl fumarate, and producing the first terminal ruthenium carbide complexes. The products are diamagnetic, air-stable, and moderately soluble in hydrocarbon solvents. An X-ray study of Ru(C:)Cl2(P(C6H11)3) (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) shows a Ru-C distance of 1.650(2) A, consistent with the presence of a very short Ru-C triple bond.