Rhenium(I) Terpyridine π-Bases: Reversible η2-Coordination of Ketones, Aldehydes, and Olefins in the Terpyridine Plane
摘要:
The complex trans-[Re(terpy)(Br)(PPh3)(2)][OTf] (2) (terpy = 2,2':6',2"-terpyridine) is a convenient precursor to the electron-rich pi-basic fragment {(terpy)(L)(2)Re}(+) (L = (BuNC)-Bu-t or PMe3). Reduction of 2 with activated magnesium in the presence of unsaturated organic molecules and an excess of either tBuNC or PMe3 yields complexes of the type trans-[(terpy)(L)(2)Re(eta(2)-pi)][OTf] (L = (BuNC)-Bu-t or PMe3; pi = olefin, aldehyde, or ketone), The dihapto-coordinated organic moieties show a preference for binding in the plane of the terpy ligand. Reaction of trans- [Re(terpy)((BuNC)-Bu-t)(2)(eta(2)-acetone)][OTf] (9) with MeOTf yields an observable mu(2)-ketonium complex, The electronic environment of these complexes has been probed by cyclic voltammetry, and the details of ligand exchange for the eta(2)-ketone complexes are presented. Geometric features determined from X-ray crystal structure analyses of trans-[(terpy)((BuNC)-Bu-t)(2)Re(eta(2)-cyclopentene)][OTf] (4) and trans-[(terpy)((BuNC)-Bu-t)(2)Re(eta(2)-acetophenone)][OTf] (11) are reported.