160604-72-8Relevant academic research and scientific papers
Preparation of Four-membered Phosphonickelocycles. Unusual Facile Stabilization of Five-co-ordinate Complexes
Font-Bardia, Merce,Gonzalez-Platas, Javier,Muller, Guillermo,Panyella, David,Rocamora, Merce,Solans, Xavier
, p. 3075 - 3084 (2007/10/02)
Three different types of organometallic compounds (R = Ph 1 or Et 1'), (R = Ph 2 or Et 2') and (R = Ph 3 or Et 3') have been obtained from 1 equivalent of PR2(C6Cl5) (R = Ph or Et), (cod = cis,cis-cycloocta-1,5-diene), and L = PMe2Ph a, PEt3 b, P(CH2Ph)3 c or PPh3 d.Complexes 2 evolve in solution, either to 1 and , or to 3 by breaking of the Ni-P bond of the four-membered ring by free phosphine.The selective preparation of compounds 1 or 3 can be achieved by performing the oxidative-addition reaction in the absence or with 2 equivalents of L respectively.When 1 equivalent of a diphosphine was used in the oxidative-addition reaction a mononuclear five-co-ordinate complex was obtained, 4 .However, dppm (Ph2PCH2PPh2) acts as a monodentate ligand to give the five-co-ordinate compound .Complexes 2, 2' show preferentially a cis geometry, 1' is trans, and 3, 3' have the L ligands in trans position.Insertion of CO or alkynes into the Ni-C bond was not observed.Compounds 1 and 1' in the presence of neutral ligands L = CO or PR3 (PR3 = PMe2Ph a or PEt3 b) gave five-co-ordinate complexes without cleavage of the Ni-P bond of the ring.Stabilization of the four-membered ring is achieved when two bidentate ligands are present or in the five-co-ordinate compound .Two bidentate ligands are also needed to stabilize the formation of five-co-ordinate complexes.The molecular structures of complexes 1', 3b, and were determined by single-crystal X-ray diffraction.
