Spectroscopic Comparison of Dinuclear Ti+ and Ti2+ μ-η1:η1 Dinitrogen Complexes with Cp*/Pentafulvene and Amine/Amide Ligation: Moderate versus Strong Activation of N2 (Eur. J. Inorg. Chem. 2/2006)

The cover picture shows that Raman spectroscopy can reveal drastically different N−N stretching frequencies in dinuclear, dinitrogen-bridged titanium complexes. In the article by F. Tuczek et al. on p. 291 ff., the recently synthesized complex [{(η5-C5Me5)Ti[η6-C5H4C(p-tolyl)2]}2(μ-η1:η1-N2)] (1; R. Beckhaus et al., Eur. J. Inorg. Chem.2005, 1003) is compared to the dinuclear (dinitrogen)titanium complex [{(Me3Si)2NTiCl(TMEDA)}2(μ-η1:η1-N2)] (3; R. Duchateau et al., J. Am. Chem. Soc.1991, 113, 8986). With respect to 3 [ν(NN) = 1284 cm−1], 1 exhibits an unusually high N−N stretching frequency [ν(NN) = 1749 cm−1]. These spectroscopic differences reflect different degrees of dinitrogen activation, which are explained by the fact that only one of the N2 π*-orbitals is occupied in 1, whereas both π*-orbitals are occupied in 3.