Spectroscopic Comparison of Dinuclear Ti + and Ti 2+ μ‐η 1 :η 1 Dinitrogen Complexes with Cp*/Pentafulvene and Amine/Amide Ligation: Moderate versus Strong Activation of N 2 (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 [{(η 5 ‐C 5 Me 5 )Ti[η 6 ‐C 5 H 4 C( p ‐tolyl) 2 ]} 2 (μ‐η 1 :η 1 ‐N 2 )] ( 1 ; R. Beckhaus et al., Eur. J. Inorg. Chem. 2005 , 1003) is compared to the dinuclear (dinitrogen)titanium complex [{(Me 3 Si) 2 NTiCl(TMEDA)} 2 (μ‐η 1 :η 1 ‐N 2 )] ( 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 N 2 π*‐orbitals is occupied in 1 , whereas both π*‐orbitals are occupied in 3 .