Formation of the fluorescent complexes [(carbene)2MII(CN)2] (M = Ni, Pd, Pt) by C-C bond cleavage of CH3CN

In the presence of NaH and OBut, 1-(9-anthracenylmethyl)-3-octylimidazolium chloride (1a) or 1-(9-anthracenylmethyl)-3-ethylimidazolium iodide (1b) was treated with Ni(OAc)(2), Pd(OAc)(2), or Pt(cod)Cl-2 in CH3CN/THF solution to afford the fluorescent complexes [1-(9-anthracenylmethyl)-3-alkylimidazol-2-ylidene](2)M(CN)(2) (2a, alkyl = C8H17, M = Ni; 2b, alkyl = C2H5, M = Ni; 3a, alkyl = C8H7, M = Pd; 3b, alkyl = C2H5, M = Pd; 4a, alkyl = C8H17, M = Pt; 4b, alkyl = C2H5, M = Pt). The metal(II) center has a square-planar geometry, and pairs of 1-(9-anthracenylmethyl)-3-alkylimidazol-2-ylidene and CN- ligands are in a trans configuration. The CN- ligand in 2-4 derives from C-C bond cleavage in the CH3CN solvent. The fluorescent emission spectra of 1-4 are determined.