Haptotropic Shifts in Organometallic Complexes with η5 Coordinated π Ligands

09/25/1999

The electronic structure and bonding of a series of tricarbonylmanganese complexes, [(ηn-X)Mn(CO)3]m, were studied by means of ab initio calculations using the B3LYP hybrid functional with a LANL2DZ basis set. The following complexes with hydrocarbon ligands were addressed (n=5, m=0): X=cyclopentadienyl (Cp=C5H5−), indenyl (Ind=C9H7−), fluorenyl (flu=C13H9−), cyclopenta[def]phenanthrenyl (cpp=C15H9−), 8-hydro-as-indacene (as-ind=C12H9−) and 5-hydro-s-indacene (s-ind=C12H9−). Two complexes with heterocyclic ligands, X=pyrrolyl (pyr=NC4H4−, n=5, m=0) and X=thiophene (tp=SC4H4, n=5, m=1+) were also studied. For all those species, in which X is a η5-coordinated π ligand, the bonding was analysed, and the optimised structures were compared with the experimentally determined X-ray structures, available from the literature. The results show a weakening of the (η5-X)Mn bond with the increasing of the ligands π system extension. The η3 species resulting from a two electrons reduction of the previous complexes were studied, their structures optimised, and a comparison between the different coordination geometries of η3-X is provided. Thus, for the fluorenyl and cyclopenta[def]phenanthrenyl complexes, an exocyclic allylic coordination was found for the reduced species (n=3, m=2−). For the indenyl and indacene reduced complexes two possible coordination geometries were studied, the exocyclic and the folded η3-X, the latter being found the more stable for all these species (X=Ind, as-ind, s-ind; n=3, m=2−). The heterocyclic ligands were shown to adopt a σ rather than a η3 coordination geometry, in the corresponding reduced complexes (m=2− for pyr and m=1− for tp).

Authors in the community:

• 

  L

  Luís Filipe Coelho Veiros

  ist12434

  Affiliations and sources

  IST > CQE

  Centro de Química Estrutural

  IST > DEQ

  Departamento de Engenharia Química

Elsevier

https://www.sciencedirect.com/science/article/pii/S0022328X99003277?via%3Dihub

Journal of Organometallic Chemistry

221

232

587

2

1872-8561

10.1016/S0022-328X(99)00327-7

chemical-sciences - Chemical sciences

eng - English