Unprecedented Formation of Azulenylidene Ligands by Reaction of the Vinylidene Ligand in Arylvinylidene Pentacarbonyl Complexes of Chromium and Tungsten with Alkoxyacetylenes
the selectivity of the reactions is low; the isomeric ratio varies between 0.5 and 2 depending on the metal and the substituent. DFT calculations on the reaction mechanism indicate that the reactions are initiated by a nucleophilic addition of the terminal carbon atom of the alkoxyacetylene to the metal-bound Cα atom of the vinylidene ligand. The low selectivity of the reactions is in accord with the
亚芳基亚乙烯基(五羰基)铬和钨配合物[(CO)5 M C C(C 6 H 4 R 1 - p)R 2 ](M = Cr,W; R 1 = H; R 2 = Me,C 6 H 4 R 3 - p [R 3 = H,Me,OMe,Cl,t Bu]; R 1 = Me; R 2 = C 6 H 4 Cl- p)与烷氧基乙炔HC⋮COR'(R'= Et ,ŤBu,金刚烷基),通过将CC三键加到亚乙烯基配体上的1,3-和环扩环得到氮杂亚烯基络合物。当使用单取代和不对称的双取代的双(芳基)亚乙烯基络合物时,获得两种异构体的混合物。在两个异构体中,取代基要么连接到七元环上,要么位于苯基的对位。通常,反应的选择性低。根据金属和取代基的不同,异构体的比率在0.5和2之间变化。对反应机理的DFT计算表明,反应通过亲核加成中的烷氧基乙炔与金属结合的C中的末端碳原子的引发α亚乙烯基配体的原子。反应的低选择性符合计
Photochromic spiropyran compounds
申请人:GEC-MARCONI LIMITED
公开号:EP0246114A2
公开(公告)日:1987-11-19
A series of novel photochromic spiropyrans are disclosed in which a spiro-adamantane group is introduced into the 2-position of the benzopyran or naphthopyran ring. The spiropyran compounds of the invention exhibit heliochromic properties, i.e. they colour in sunlight and fade rapidly at ambient temperatures in the absence of U.V. light, making them good candidates for use in the manufacture of sunglasses. The invention includes lenses which darken in sunlight and incorporate the novel spiropyrans and a process for the preparation of the spiropyran compounds.