Short C−H⋅⋅⋅halogen distances in the crystals and remarkably low‐field shifts of the 1H NMR signals of the bridging hydrogen atoms are the characteristic features of the intramolecular C−H⋅⋅⋅halogen hydrogen bonds that are exhibited by several new (1,4‐diaza‐1,3‐diene)titanium and ‐niobium halides (the structure of 1 is depicted here). Whether the additional support of the resonance‐stabilized heterodiene ligands is required for the occurrence of these weak interactions still remains to be clarified.

Reactions of HgR 2 (R = CH 2 CH 2 Ph, 1a; CH 2 CH 2 CH 2 Ph, 1b; CH 2 CHMePh, 1c) (prepared from HgCl 2 and the requisite Grignard compounds) with lithium in toluene afforded (phenylalkyl)lithium compounds LiR (2a−c) in yields of between 64 and 81%. At −30°C, they react with [PdCl 2 (dppe)] [dppe = 1,2-bis(diphenylphosphanyl)ethane] yielding bis-(phenylalkyl)palladium(II) complexes [PdR 2 (dppe)] (3a−c) which were isolated (T dec = 159°C, 3a; 80°C, 3b; 145°C, 3c) and fully characterized by 1 H, 13 C, and 31 P NMR spectroscopy.Single-crystal X-ray diffraction of [Pd(CH 2 CH 2 Ph) 2 (dppe)] (3a) showed that the palladium atom is square-planar coordinated by two 2-phenylethyl ligands and the dppe ligand. The two CH 2 CH 2 Ph ligands exhibite nearly a fully staggered conformation. Overall, a good approximation for the complex is that it has C 2 symmetry with the C 2 axis defined by the Pd atom and the midpoint of the central C−C bond of the dppe ligand. Bis(phenylalkyl)palladium complexes 3a and 3b reacted with PhSH in a 1:1 ratio yielding [PdR(SPh)(dppe)] (R = CH 2 CH 2 Ph, 5a; CH 2 CH 2 CH 2 Ph, 5b), whereas in the case of complex 3c, besides [Pd(CH 2 CHMePh)(SPh)(dppe)] (5c), a considerable [a]

Kurze C−H⋅⋅⋅Halogen‐Abstände in den Kristallen und auffallende Tieffeldverschiebungen der 1H‐NMR‐Signale der Brückenwasserstoffatome sind die charakteristischen Merkmale der intramolekularen C−H⋅⋅⋅Halogen‐Wasserstoffbrücken, die einige neue (1,4‐Diaza‐1,3‐dien)titan‐ und ‐niobhalogenide aufweisen (das Bild zeigt die Struktur von 1). Ob für das Auftreten dieser schwachen Wechselwirkungen die zusätzliche Unterstützung des resonanzstabilisierten Heterodienliganden erforderlich ist, muß noch geklärt werden.