排序方式: 共有25条查询结果,搜索用时 15 毫秒
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Mathieu Lafage Dr. Hadrien Heuclin Dr. Xavier‐Frédéric Le Goff Dr. Nathalie Saffon‐Merceron Dr. Nicolas Mézailles 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):16995-17003
The synthesis of two novel titanium carbene complexes from the bis(thiophosphinoyl)methanediide geminal dianion 1 (SCS2?) is described. Dianion 1 reacts cleanly with 0.5 equivalents of [TiCl4(thf)2] to afford the bis‐carbene complex [(SCS)2Ti] ( 2 ) in 86 % yield. The mono‐carbene complex [(SCS)TiCl2(thf)] ( 3 ) can also be obtained by using an excess of [TiCl4(thf)2]. The structures of 2 and 3 are confirmed by X‐ray crystallography. A strong nucleophilic reactivity towards various electrophiles (ketones and aldehydes) is observed. The reaction of 3 with N,N′‐dicyclohexylcarbodiimide (DCC) and phenyl isocyanate leads to the formation of two novel diphosphinoketenimines 8 a and 8 b . The bis‐titanium guanidinate complex 9 is trapped as the by‐product of the reaction with DCC. The X‐ray crystal structures of 8 a and 9 are presented. The mechanism of the reaction between complex 3 and DCC is rationalized by DFT studies. 相似文献
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Hadrien Heuclin Dr. Xavier F. Le Goff Dr. Nicolas Mézailles 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(50):16136-16144
A new unsymmetrical geminal dianion that contained both a phosphine oxide moiety and a phosphine sulfide moiety has been synthesized. Its reactivity towards RuII was explored, which led to the formation of a highly reactive carbene complex that evolved at room temperature to yield a kinetic orthometalated RuII complex through C? H activation of the phenyl group of the phosphine oxide moiety. This insertion was found to be thermally reversible and a second C? H insertion occurred at a phenyl group of the phosphine sulfide moiety to form the thermodynamic orthometalated RuII complex in a diastereospecific manner. DFT calculations fully rationalized the experimental findings in terms of the relative energies of the kinetic and thermodynamic products and allowed the mechanism of this process to be fully understood. 相似文献
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Local search and constraint programming for the post enrolment-based course timetabling problem 总被引:1,自引:0,他引:1
Hadrien Cambazard Emmanuel Hebrard Barry O’Sullivan Alexandre Papadopoulos 《Annals of Operations Research》2012,194(1):111-135
We present a variety of approaches for solving the post enrolment-based course timetabling problem, which was proposed as
Track 2 of the 2007 International Timetabling Competition. We approach the problem using local search and constraint programming
techniques. We show how to take advantage of a list-colouring relaxation of the problem. Our local search approach won Track
2 of the 2007 competition. Our best constraint programming approach uses an original problem decomposition. Incorporating
this into a large neighbourhood search scheme seems promising, and provides motivation for studying complete approaches in
further detail. 相似文献