Cationic and neutral palladium(II) methyl complexes of di-N-heterocyclic carbenes

Cationic and neutral methyl complexes of Pd(II) incorporating di-N-heterocyclic carbenes, (CCmeth)-C-tBa and (CCeth)-C-tBu (where (CCmeth)-C-tBu = 1, 1'-methylene-3,3'-di-tert-butyldiimidazol-2,2'-diylidene and (CCeth)-C-tBu = 1,2-ethylene-3,3'-di-tert-butyldiimidazol-2,2'-diylidene), have been prepared. The complexes [Pd((CCmeth)-C-tBu)Me-2] (1) and [Pd((CCeth)-C-tBu)Me-2] (2) have been isolated and 2 has been characterised by single crystal X-ray diffraction. When I and 2 are dissolved in deuterated methanol in the presence of pyridine or bipyridine the four coordinate cations [Pd((CCmeth)-C-tBu)MC(py)(+) (3), [Pd((CCeth)-C-tBu)Me(py)(+) (4), [Pd(C-tBu(D)-eta-C-meth)Me(eta(2)-bipy)](-) (5), and [Pd(C-tBu(D)-eta-C-eth)Me(eta(2)-bip)(+) (6). are observed spectroscopically.