Reactions of lithium amidinates or guanidinates toward carbodiimides: Synthesis and characterization of multi-site triazapentadienyllithium compounds

Four novel lithium complexes [(2,6-iPr2C6H3)NC(R)NC{N(SiMe3)(Cy)}N(Cy)]Li⋅TMEDA (R = NMe2, 1; 1-piperidino, 2; 3-pyridyl, 3) and [{(2,6-iPr2C6H3)NC(NMe2)NC{N(SiMe3)(iPr)}N(iPr)}Li]2 (4) were prepared. Their structures were confirmed by X-ray crystallographic methods and their formation was proposed. [Display omitted] Lithium amidinates or guanidinates form novel complexes 1–4 with N,N′-dicyclohexylcarbodiimide (CyN=C=NCy, DCC) or N,N′-diisopropylcarbodiimide (iPrN=C=NiPr, DIC). Their structures were characterized by spectroscopic and X-ray crystallographic method. The X-ray diffraction analysis revealed that heteroleptic complexes 1–3 were mononuclear with a four-co-ordinate metal center and homoleptic 4 was dimeric. Both the W-shaped 1,3,5-triazapentadienato lithium 1–3 and U-shaped 4 could be regarded as good intermediates en route to their metal complexes with varied substrates.