Cyclopentadienyl metal alkynyl complexes

The NLO properties of cyclopentadienyl metal alkynyl complexes have also proven an especially popular research topic, particularly those containing Group 8 metals. Most of the studies have involved... 

Redox-switchable quadratic hyperpolarisabilities have also been demonstrated with electron-rich cyclopentadienyl metal alkynyl com-plexes. A series of Fe" and Fe complexes featuring acceptor groups such as NO2 or CN have been prepared and their /u/1 values measured by EFISH at 1.91 um (e.g. 96). As expected, the Fe complexes show considerably depressed fj,p values, relative to those of the Fe congeners (Figure 1.45). 

Reactions of cyclopentadienyl- and (pentmethylcyclopentadienyl)iron dicarbonyl 2-alkynyl complexes as well as cyclopentadienylmolybdenum tricarbonyl 2-alkynyl complexes with 4,5-diphenyl-3,6-dihydro-l,2-dithiin 1-oxide 111 were shown to yield transition metal-substituted five-membered ring thiosulfinate esters 112 in moderate to excellent yields (Scheme 27) <19910M2936, 1989JA8268>. These reactions are formal [3-1-2] cycloadditions. When... 

For the metal—alkyne fragmait, nonlinearity also increases upon increasing valence electron count [14 valence electron (triphenylphosphine) gold alkynyl compounds <18 valence electron (cyclopentadienyl) (triphenylphosphine)nickel, and (cyclopentadienyl) bis(triphenylphosphine) ruthenium alkynyl compounds] and increasing ease of oxidation (less easily oxidizable (cyclopentadienyl)(tri-phenylphosphine)nickel alkynyl complexes < more easily oxidizable (cyclopen-tadienyl)bis(triphenylphosphine)ruthenium alkynyl complexes). 

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