Selenophene transition metal complexes

Abstract

The series of rj^-selenophene transition metal complexes (t|5-Seln)Cr(C0)3 (1-3), [(RI5-Seln)Mn(C0)3]S03CF3 (4-6), [(t|5-Seln)RuCp*]S03CF3 (7-9), and [(ri5-Seln)IrCp*](BF4)2 (10-12), where Seln = selenophene(Sel), 2methylselenophene (2-MeSel), or 2,5-dimethylselenophene(2,5-Me2Sel), were synthesized and characterized by ^H, and "^"^Se NMR and IR spectroscopy. The molecular structxire of (t|5-2,5-Me2Sel)Cr(CO)3 (3) was determined. Reactions of KT|^-Sel)Mn(C0)3]S03CF3 (4) with nucleophiles (Nuc = H~, CN~) give the neutral addition products [(Sel*Nuc)Mn(C0)3] (Nuc = H~ (4a), Nuc = CN~ (4b)) in which three carbon atoms and the Se are bonded to the Mn. The reaction of [(ri^-SeDRuCp^lSOsCFs (7) with H~, however, results in cleavage of the C-Se bond to form a butadiene selenide complex ((ri5-SeCH=CH-CH=CH2)RuCp*) (7a). Still another type of product results from the reaction of [(TI5-2,5-Me2Sel)IrCp*](BF4)2 (12) with two equivalents of H~; in this case, the H~ acts as a reducing agent to give the ring-opened complex (C, Se-2,5-Me2Sel)IrCp* (12a). All of these reactions are similar to those of the analogous t|5-thiophene complexes. The "^"^Se NMR chemical shift values for the tj^-Seln ligands in complexes 1-12 fall within a range of 225 ppm; they are influenced