title: Unique coordination of two C=C double bonds to an electron-deficient lead center.
abstract: Reaction of bis(cyclopentenemethyl)diethylplumbane (2) with trityl cation leads to the formation of the plumbyl cation bis(cyclopentenemethyl)plumbylium (1), in which the positively charged lead atom interacts with the two C=C double bonds of the cyclopentene ligands. The plumbyl cation 1 is characterized by NMR spectroscopy (delta((207)Pb)=807 ppm, delta((13)C(C=C))= 136.1 ppm, (1)J(Pb,C=C)=14.4 Hz) and X-ray crystallography. The structure of 1 reveals a distorted trigonal-bipyramidal coordination sphere for the lead atom with a unique coordination of two C=C double bonds in apical positions. According to quantum-mechanical calculations (MP2/6-311G(d,p) (C, H), SDD (Pb)//MP2/6-31G(d), SDD (Pb)) this interaction stabilizes 1 by 28.3 kcal mol(-1) relative to the tricoordinated plumbylium ion 10. An "atoms in molecules" (AIM) analysis indicates a pi-type interaction between the lead atom and the C=C double bonds, reminiscent of that in the 2-norbornyl cation.
authors.affiliation: Institut für Anorganische Chemie, Goethe Universität Frankfurt/Main, Marie Curie Strasse 11, Germany. dr.thomas.mueller@chemie.uni-frankfurt.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller
authors.forename: Christian
authors.initials: C
authors.lastname: Bauch
authors.forename: Michael
authors.initials: M
authors.lastname: Bolte
authors.forename: Norbert
authors.initials: N
authors.lastname: Auner