Synthesis, reactivity and DFT investigation of a cationic zirconocene benzyl compound with an appended phenyl group

The reaction of [eta(5)-C5H5-(eta(5)-C5H4CMe2C6H4Me)Zr(CH2Ph)(2)] (1) with the cation generating agent B(C6F5)(3) was studied by means of multinuclear NMR and density functional theory (DFT) methods. The clean reaction in CD2Cl2 at similar to 60 degrees C yielded the cationic compound [eta(5)-C5H5-(eta(5):eta(1)-C5H4-CR2C6H4R)Zr(eta(2)-CH2Ph)] (R = Me: 2, R = H: 3), with a tolyl moiety coordinated to the cationic zirconium centre, in addition to the expected eta(2)-coordination of the benzyl moiety. Both coordinations were unambiguously assigned by multinuclear one- and two-dimensional NMR spectroscopy. Detailed DFT calculations of congener 3 at the B3LYP level of theory explain the unusual chemical shift of the coordinated atom of the tolyl moiety. Furthermore, detailed electronic analysis (Bader and NBO analysis) were undertaken to ascertain the type of coordination (agostic versus electrostatic) that the tolyl moiety adopts. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheirn, Germany, 2007)