Abstract1,3-Di̲aza-2-s̱ila-4-c̱yclopentenes 1 (DISC), which are electron-rich and easily oxidizable ole fins, form strongly coloured, but poorly soluble 1:1 adducts with cuprous halides, while silver trifluoromethylsulfonate oxidizes 1. Much more soluble and again strongly coloured complexes of stoichiometry LPdX2, (L)1.5PdX2 and L 2PdX2 are formed from 1 and palladium halides. The well-crystallizing adduct (PdCl2 · L)2 3a was chosen for an X-ray structure analysis (monoclinic, space group P2/c; a = 10.215(3), b = 14.681(3), c =23.642(5) Å , β = 101.31(2)°; Z = 8 ; R = 0.054), which revealed an almost planar DISC ligand in an oblique η2(C=C)-coordination relative to the π-plane. Structural data and rather peculiar spectroscopic properties encourage a comparison of 3a with complexes, in which an electron-rich olefin is split to give a bis(carbene) ligand system. The electronic reasons for the splitting of electron-rich olefins at d8 metals are discussed under symmetry considerations.
