Palladium(II) and Platinum(II) Complexes with Bisphosphanes, [S 2 C=C(CN) 2 ] 2– and [Se 2 C=C(CN) 2 ] 2– as Chelating Ligands

The palladium(II) and platin(II) 1, 1‐dicyanoethylene‐2, 2‐dithiolates [(L–L) M {S 2 C=C(CN) 2 }] ( M = Pd: L–L = dppm, dppe, dcpe, dpmb; M = Pt: dppe, dcpe, dpmb) were prepared either from[(L–L) M Cl 2 ] and K 2 [S 2 C=C(CN) 2 ] or from [(PPh 3 ) 2 M {S 2 C=C(CN) 2 }] and the bisphosphane. Moreover, [(dppe)Pt{S 2 C=C(CN) 2 }]was obtained from [(1, 5‐C 8 H 12 )Pt{S 2 C=C(CN) 2 }] and dppeby ligand exchange. The 1, 1‐dicyanoethylene‐2, 2‐diselenolates[(dppe) M {Se 2 C=C(CN) 2 }] ( M = Pd, Pt) were prepared from[(dppe) M Cl 2 ] and K 2 [Se 2 C=C(CN) 2 ]. The oxidation potentials of the square‐planar palladium and platinum complexes were determined by cyclic voltammetry. The reaction of [(dcpe)Pd(S 2 C=O)] with TCNE led to a ligand fragment exchange and gave the 1, 1‐dicyanoethylene‐2, 2‐dithiolate [(dcpe)Pd{S 2 C=C(CN) 2 }] in good yield.