Gold(I) eta2-arene complexes.

The reaction of 9-{[N-n-propyl-N-(diphenylphosphino)amino]methyl}anthracene (1) with Au(SMe2)Cl yields complex 2 with an arm-opening configuration. The latter is treated with AgClO4 to form complex 4 and then respectively reacted with acetonitrile, pyridine, and triphenylphosphine sulfide to afford novel gold(I) eta2-arene complexes 3a-c, which have arm-closing configurations and feeble or weak fluorescence emissions. The observation can be attributed to charge transfer from the anthracene unit to the Au+ ion. When the solution of 3a or 4 in CH2Cl2 was added with 1 equiv of Ph3P, complex 5 with the arm-opening configuration was formed and strong emission was restored.