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Your search keyword '"Nigel T. Lucas"' showing total 2 results
Start Over Author "Nigel T. Lucas" Publisher american chemical society
2 results on '"Nigel T. Lucas"'

1. Gold(I) and Palladium(II) Complexes of 1,3,4-Trisubstituted 1,2,3-Triazol-5-ylidene 'Click' Carbenes: Systematic Study of the Electronic and Steric Influence on Catalytic Activity

Author

Paul C. Young, Ai-Lan Lee, Nigel T. Lucas, James R. Wright, and James D. Crowley

Subjects
Steric effects, Allylic rearrangement, 010405 organic chemistry, Chemistry, Stereochemistry, Organic Chemistry, One-pot synthesis, Regioselectivity, chemistry.chemical_element, Infrared spectroscopy, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, Article, 0104 chemical sciences, Catalysis, Inorganic Chemistry, Cycloisomerization, Physical and Theoretical Chemistry, Palladium
Abstract

The synthesis of a small family of six electronically and sterically modified 1,3,4-trisubstituted 1,2,3-triazol-5-ylidene gold(I) chloride complexes is described. Additionally, the corresponding trans-[PdBr2(iPr2-bimy)(1,3,4-trisubstituted 1,2,3-triazol-5-ylidene)] complexes are also generated and used to examine the donor strength of the 1,3,4-trisubstituted 1,2,3-triazol-5-ylidene ligands. All compounds have been characterized by 1H and 13C NMR and IR spectroscopy, high-resolution electrospray mass spectrometry (HR-ESI-MS), and elemental analysis. The molecular structures of four of the gold(I) and four of the palladium(II) complexes were determined using X-ray crystallography. Finally, it is demonstrated that these 1,2,3-triazol-5-ylidene gold(I) chloride complexes (Au(trz)Cl) are able to catalyze the cycloisomerization of 1,6-enynes, in high yield and regioselectivity, as well as the intermolecular direct etherification of allylic alcohols. Exploiting the Au(trz)Cl precatalysts allowed the etherification of allylic alcohols to be carried out under milder conditions, with better yield and regioselectivity than selected commercially available gold(I) catalysts.

Published
2013

2. Mixed-Metal Cluster Chemistry. 30.1Syntheses and Optical Limiting Properties of Cluster-Containing Oligo- and Polyurethanes.

Author

Michael D. Randles, Nigel T. Lucas, Marie P. Cifuentes, Mark G. Humphrey, Matthew K. Smith, Anthony C. Willis, and Marek Samoc

Subjects
*POLYMERS, *CHROMIUM group, *MICROCLUSTERS, *MOLYBDENUM
Abstract

Molybdenum−iridium clusters Mo2Ir24-2-C2(CH2)6OH2(-CO)4(CO)4(-C5H4R)2R H (5), Me (6), (CH2)9O(THP) (7); THP tetrahydropyranyl are formed from reaction of Mo2Ir2(-CO)3(CO)7(-C5H4R)2with the alkyne HO(CH2)6C2(CH2)6OH. Reaction of 6and 7with the diisocyanate OCN(CH2)4NCO affords oligourethanes −O(CH2)6(4-2-C2)Mo2Ir2(-CO)4(CO)4(-C5H4R)2(CH2)6OC(O)NH(CH2)4NHC(O)−nR Me (12), (CH2)9O(THP) (13), with transition metal clusters in the backbone, the extent of polymerization being ascertained by size exclusion chromatography and 1H NMR spectroscopy. Characterization of the cluster-containing oligo- and polyurethanes was aided by 1H NMR and IR spectral comparison with model cluster diurethanes Mo2Ir24-2-C2(CH2)6OC(O)NH(CH2)3Me2(-CO)4(CO)4(-C5H4R)2R H (8), Me (9), (CH2)9O(THP) (11), prepared from reaction between the cluster diols 5, 6,and 7and the isocyanate Me(CH2)3NCO. The diol cluster 5and cluster diurethane 8have been characterized by single-crystal X-ray diffraction studies. Removal of the THP groups in 13gives −O(CH2)6(4-2-C2)Mo2Ir2(-CO)4(CO)4(-C5H4(CH2)9OH)2(CH2)6OC(O)NH(CH2)4NHC(O)−n(14), which has been cross-linked on reaction with OCN(CH2)4NCO. The cluster content of the polyurethanes can be diluted; polymerization of 1:19 6:1,6-hexanediol and OCN(CH2)4NCO affords copolymer −O(CH2)6(4-2-C2)Mo2Ir2(-CO)4(CO)4(-C5H4Me)2(CH2)6OC(O)NH(CH2)4NHC(O)O(CH2)6OC(O)NH(CH2)4NHC(O)m−n(16). The optical limiting properties of these dimolybdenum-diiridium clusters and cluster-containing polymers, and related molybdenum-triiridium clusters and tungsten-containing homologues, have been assessed by open-aperture Z-scan studies at 527 nm employing ns pulses. Optical limiting merit increases upon increasing group 6 metal content, and replacing the 4d metal molybdenum with the 5d metal tungsten. Some insight into the mechanism by which these clusters function as optical limiters has been gleaned from complementary pump−probe studies, with their behavior consistent with a fast nonlinear absorption process followed by reverse saturable absorption involving metastable excited states of greater than nanosecond lifetime. [ABSTRACT FROM AUTHOR]

Published
2007
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