Lithium 5-(2-Diphenylphosphinoethyl)-1,2,3,4-tetramethylcyclopentadienide: On the Regioselectivity of the Alkylation of Tetramethylcyclopentadienide Anion.

D.P. Krut'ko, M.V. Borzov, E.N. Veksler, E.M. Myshakin, and D.A. Lemenovskii

Russ. Chem. Bull., 47 (5), p. 956-959 (1998)

ABSTRACT. Treatment of a mixture of isomeric (2-chloroethyl)-1,2,3,4-tetramethylcyclopentadienes (2), (3), and (7) with lithium diphenylphosphide leads to novel 4,5,6,7-tetramethylspiro[2,4]hepta-4,6-diene (6) among the reaction products. A reaction of spiroheptadiene (6) with excess LiPPh2 at elevated temperature produces lithium 5-(2-diphenylphosphinoethyl)-1,2,3,4-cyclopentadienide (8) in an almost quantitative yield. The regioselectivity of alkylation of tetramethylcyclopentadienide-anion is estimated on the basis of the ab initio quantum chemical calculations (RHF/6-311+G(d,p) for C5(CH3)4H-, program package GAUSSIAN94). The total atomic charges on the ring carbons are deter-mined in the framework of the Bader's theory of atoms in molecules (program package AIMPAC).

Laboratory of Coordination Organometallic Compounds