339591-54-7Relevant academic research and scientific papers
Zwitterionic adducts from addition of imines to the α-carbon atom of pentacarbonyl(vinylidene)chromium and -tungsten complexes
Fischer, Helmut,Kirchbauer, Frank,Früh, Angelika,Abd-Elzaher, Mokhles M.,Roth, Gerhard,Karl, Christoph C.,Dede, Markus
, p. 165 - 173 (2001)
Imines, Im, such as MeN=C(Ph)H (5), 2-methyl 4,5-dihydrothiazole (8a), 2-methyl 4,5-dihydrooxazole (8b) and MeN=C(OMe)Me (13) add to the α-carbon atom of the vinylidene ligand in [(CO)5Cr=C=CMe2] (4) to give isolable zwitterionic adducts, [(CO)5Cr--C(=CMc2)(Im-)]. The reaction of [(CO)5W=C=CPh2] (12) with 13 also yields an adduct, [(CO)5W--C(=CPh2){NMe=C(OMe)Me}+] (15), whereas from the corresponding reaction of 4 with xanthylideneimine, H-N=C(C6H4)2O (16), a carbene complex, [(CO)5Cr=C(i-Pr)-N=C(C6H4)2O] (17), is obtained. Complex 17 presumably is formed by initial addition of 16 to 4 and subsequently rapid rearrangement. In solution, the adduct [(CO)5Cr--C(=CMe2)(NMe=C(Ph)H)+] (6) slowly cyclizes to form the 2-azetidin-1-ylidene complex [(CO)5Cr=C-NMe-C(Ph)H-CMe2] (7). In contrast, when solution of those zwitterions are heated that are formed by addition of 4,5-dihydrothiazole or 4,5-dihydrooxazole to 4, no cyclization is observed but rather the formation of 4,5-dihydrothiazole and 4,5-dihydrooxazole complexes, respectively. The structures of two adducts, [(CO)5Cr--C(=CMe2)(Im+)] (Im = MeN=C(Ph)H, 2-methyl 4,5-dihydrothiazole) and of the substitution product [(CO)5W(2-methyl 4,5-dihydrothiazole)] have been established by X-ray structural analyses.
