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Thioselenocarboxylic Ester, Selenetane, and Dihydrodiselenine Complexes Prepared from Pentacarbonyl(selenobenzaldehyde)tungsten with ?-Donor-Substituted Alkynes
Fischer, Helmut,Treier, Kornelia,Troll, Carsten
, p. 1149 - 1156 (2007/10/03)
Pentacarbonyltungsten-coordinated selenobenzaldehyde, > (1), reacts with t-Bu-CC-SMe (2) by insertion of the CC into the Se=C bond to form in a highly regio- and stereoselective manner the α,β-unsaturated thioselonocarboxylic ester complex (Z)(C=C)-1-Se=C(SMe)C(t-Bu)=C(Ph)H>> (3).The thioselonocarboxylic ester ligand is cleaved intact from the metal by treatment of 3 with Br.Three complexes are formed in the reaction of 1 with Me-CC-SMe (5): the thioselonocarboxylic ester complex 1-Se=C(SMe)C(Me)=C(Ph)H>> (6) as a mixture of the (E) and (Z)(C=C) isomers, a selenetane complex (7) and a dihydrodiselenine complex (8).The product distribution depends on the ratio 1:5 and the solvent.The reaction of 1 with the bis(organylthio)alkynes RS-CC-SR (9) a), i-Pr (b), 2,6-C6H3Me2 (c)> yields mixtures of the (E) and (Z)(C=C) isomers of the α,β-unsaturated α-organylthio thioselonocarboxylic ester complexes 1-Se=C(SR)C(SR)=C(Ph)H>> (10a-c).In contrast, the reaction of 1 with tert-butoxyethyne, H-CC-O(t-Bu) (11), affords a bis(pentacarbonyltungsten) 5,6-dihydro-1,2-diselenine complex (12).Compound 12 is probably formed by consecutive reaction of 1 with 11 to give the selenocarboxylic ester complex 1-Se=C(O(t-Bu)C(H)=C(Ph)H>> which then further reacts as a heterodiene by highly regioselective cycloaddition with the Se=C bond of a second molecule of 1 to give 12.In the reaction of 1 with 5 and 9a the isomer with a trans arrangement of C(=Se)SMe and Ph is the kinetically controlled reaction product .The formation of (E)-6 and (Z)-10a is followed by isomerization until an (E)/(Z) equilibrium in reached.Complexes 3 and 7 were characterized by X-ray structural analyses. - Keywords: Selenoaldehyde complex; Thioselenocarboxylic ester complexes; Selenetane complex; Dihydrodiselenine complex
