Pulsed-field ionization electron spectroscopy and conformation of copper-diammonia

Copper-diammonia, Cu(NH3)2, and its deuterated species, Cu(ND3)2, are produced in supersonic molecular beams and studied by pulsed-field ionization zero electron kinetic energy photoelectron spectroscopy and ab initio calculations. Structural isomers with a copper atom binding to an ammonia dimer or two ammonia molecules are obtained by the calculations. By comparing the experimental measurements to the theoretical calculations, the neutral and ionic forms of copper-diammonia are determined to be in a doubly bound linear conformation in their ground electronic states. The adiabatic ionization potentials of Cu(NH3)2 and Cu(ND3)2 are measured as 29 532 (5) and 29313(5)cm−1, respectively. The metal-ligand symmetric stretching frequencies are measured to be 436cm−1 for Cu+–(NH3)2 and 398cm−1 for Cu+–(ND3)2, and the metal-ligand bending frequencies 75∕139cm−1 for Cu∕Cu+–(NH3)2 and 70∕125cm−1 for Cu∕Cu+–(ND3)2. Moreover, the dissociation energy of Cu(NH3)2→CuNH3+NH3 is determined to be 11(3)kcalmol−1 through a ...