The series of η5-selenophene transition metal complexes (η5-Seln)Cr(CO)3 (1-3), [(η5-Seln)Mn(CO)3]SO3CF3(4–6), [(η5-Seln)RuCp*]SO3CF3(7–9), and [(η5-Seln)IrCp*](BF4)2 (10-12), where Seln = selenophene (Sel), 2-methylselenophene (2-MeSel), or 2,5-dimethylselenophene (2,5-Me2Sel), were synthesized and characterized by 1H, 13C, and 77Se NMR and IR spectroscopy. The molecular structure of (η5-2,5-Me2Sel)Cr(CO)3 (3) was determined. Reactions of [(η5-Sel)Mn(CO)3]SO3CF3(4) with nucleophiles (Nuc = H-, CN-) give the neutral addition products [(Sel-Nuc)Mn(CO)3] [Nuc = H-(4a), Nuc = CN-(4b)] in which three carbon atoms and the Se are bonded to the Mn. The reaction of [(η5-Sel)RuCp*]SO3CF3(7) with H-, however, results in cleavage of the C-Se bond to form a butadiene selenide complex ((η5-SeCH═CHCH═CH2)RuCp*) (7a). Still another type of product results from the reaction of [(η5-2,5-Me2Sel)IrCp*](BF4)2 (12) with 2 equiv 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 η5-thiophene complexes. The 77Se NMR chemical shift values for the η5-Seln ligands in complexes 1–12 fall within a range of 225 ppm; they are influenced by the metal and its ligands, the charge on the complex, and the number of methyl groups in the selenophene.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry