Binuclear pentalene manganese carbonyl complexes: conventional trans and unconventional cis structures

摘要

The binuclear pentalene manganese carbonyl trans-(η5,η5-C₈H₆)Mn₂(CO)₆ has been synthesized by the reaction of the pentalene dianion with a manganese carbonyl halide. This species as well as its decarbonylation products (C₈H₆)Mn₂(CO) _n (n = 5, 4, 3) have been investigated by density functional theory. In all of these optimized structures both pentalene rings are bonded to manganese atoms as pentahapto ligands. The lowest energy (C₈H₆)Mn₂(CO)₆ structure is the experimentally observed singlet trans structure but a closely related cis structure lies 7 kcal/mol higher. The lowest energy (C₈H₆)Mn₂(CO)₅ structure is a singlet structure having a four-electron donor bridging CO group and a Mn-Mn single bond of length 2.9 à . The lowest energy (C₈H₆)Mn₂(CO)₄ structure is a singlet structure having all terminal CO groups and a short Mn ≡ Mn triple bond of length 2.3 à . For (C₈H₆)Mn₂(CO)₃ low energy structures are found with either triplet or quintet spin states. Low energy structures with pentalene rings only partially bonded to manganese atoms were found for the carbonyl-rich species (C₈H₆)Mn₂(CO) _n (n = 7, 8). However, the latter species are predicted not to be viable with respect to carbonyl loss to give the stable (C₈H₆)Mn₂(CO)₆.View full textDownload full textRelated var addthis_config = { ui_cobrand: "Taylor & Francis Online", services_compact: "citeulike,netvibes,twitter,technorati,delicious,linkedin,facebook,stumbleupon,digg,google,more", pubid: "ra-4dff56cd6bb1830b" }; Add to shortlist Link Permalink http://dx.doi.org/10.1080/00268976.2012.663942