| Abstrakt: |
The fulvene complexes (η6-C5Me4CH2)Re(CO)2R (1, R = C6F5; 2, R = I) react at the exocyclic methylene carbon with allylmagnesium chloride or 2-thienyllithium to yield the anionic species [(η5-C5Me4CH2L)Re(CO)2R]- (L = −CH2CH&dbd;CH2, −2-C4H3S). Further reaction with CH3I at room temperature affords the methyl complexes (η5-C5Me4CH2L)Re(CO)2(R)(Me) (3, R = C6F5; 4, R = I). Protonation of the anionic species with HCl at low temperature gives the hydride complexes trans-(η5-C5Me4CH2L)Re(CO)2(R)(H) (5, R = C6F5; 6, R = I). Thermolysis of hexane solutions of 6, under CO atmosphere, produces the tricarbonyl complexes (η5-C5Me4CH2L)Re(CO)3 (7) in moderate yields; if the reaction is carried out in the presence of PMe3, the analogous dicarbonyl phosphine derivatives (η5-C5Me4CH2L)Re(CO)2(PMe3) (9) are obtained, but no coordination of the lateral functionality is observed. In clear contrast, thermolysis of hexane solutions of the pentafluorophenyl hydride complexes trans-(η5-C5Me4CH2L)Re(CO)2(C6F5)(H), even under CO atmosphere, yields the chelated complexes (η5:ηx-C5Me4CH2L)Re(CO)2 (8a, L = −CH2CH&dbd;CH2, x = 2; 8b, L = −2-C4H3S, x = 1). However, prolonged thermal treatment of 8b under a CO atmosphere affords the corresponding tricarbonyl complex 7b. The molecular structures of 8a and 9b have been determined. Both molecules exhibit formal three-legged piano-stool structures, with three terminal ligands in 9b (two CO and one PMe3), but in the case of 8a, in addition to the two CO's, the third position corresponds to the η2-coordination of the butenyl substituent of the η5-C5Me4 ring. Attempts to displace the coordinated sidearm in complex 8a have been investigated, as well as the photochemical reactions of tricarbonyl complexes 7. |
