The spectroscopic properties and crystal structures of the gold (I) arylacetylide complexes [(R3P) Au (C⋮ CAr)](R= Cy, Ar= 4-nitrophenyl, 1; 4-trifluoromethylphenyl, 2; pentafluorophenyl, 3; R= Ph, Ar= 4-nitrophenyl, 4) have been examined. The dipole-allowed and-forbidden transitions of 1 (4 in parentheses) at λmax 340 (336) and ca. 485 (470) nm in CH2Cl2 solution at 298 K are assigned to the singlet and triplet intraligand charge transfer ...