Dissociation Energies of the Cu and Ag Monohalides and of Ni Monofluoride

Abstract

Gaseous isomolecular equilibria of the type CuX + Ag = Cu + AgX, where X = F, Cl, Br, and I, were studied by effusion-beam mass spectrometry at elevated temperatures, and the differences between the dissociation energies of the CuX and AgX molecular species were determined with relatively high accuracy from thermochemical analysis of the equilibrium data. Analysis of literature data, plus new information on AgBr, yielded accurate values of D degrees 0 in kcal mol(-1) for CuF (102.0), AgCl (74.4), AgBr (66.4), and AgI (59.7), from which values were derived for AgF (81.5), CuCl (89.6), CuBr (79.2), and CuI (69.4), all +/-1 kcal mol(-1). The result is a consistent set of dissociation energies for all eight of the Cu and Ag monohalides that will be useful in checking the reliability of quantum chemical calculations for these molecular species containing elements of increasing atomic number. Also, the isomolecular exchange equilibrium between CuF and NiF was studied in a similar fashion, leading to D degrees 0(NiF) = 104.4 +/- 1.4 kcal mol(-1).

Reduction from copper(II) to copper(I) upon collisional activation of (pyridine)2CuCl+

“… d Derived from IE(Cu) = 7.72638 eV,58 IE(CuCl) = 10.7 ± 0.3 eV,58 and BDE(Cu‐Cl) = 378 ± 4 kJ mol −1 59…”

Theory meets experiment: Gas-phase chemistry of coinage metals

“…With regard to the coinage metals, especially Hildenbrand and Lau have provided valuable data for copper-and silver-halides using hightemperature mass spectrometry, i.e. CuF [110], CuCl [111], AgF [110], AgCl [111], and AgBr [112], whereas most information about neutral AuX species has been gathered by ion-molecule reactions [100,113,114].…”

Ligand Effects on the Mechanisms of Thermal Bond Activation in the Gas‐Phase Reactions NiX+/CH4→Ni(CH3)+/HX (X=H, CH3, OH, F). Short Communication

“…The NiF þ /CH 4 System. In contrast to the unreactive Ni II halides NiX þ (X ¼ Cl, Br, I), diatomic NiF þ brings about exothermic [19b,c] [21] ligand exchange with CH 4 , as mentioned earlier in the context of an exhaustive study on ligand and substrate effects in NiX þ /RH couples (X ¼ F, Cl, Br, I; R ¼ CH 3 , C 2 H 5 , n-C 3 H 7 , n-C 4 H 9 ) [22]. Recent experiments [16] reveal the existence of a quite large intramolecular KIE of 3.3, derived from the reaction of NiF þ with CH 2 D 2 ; clearly, breaking the CÀH(D) and making the FÀH(D) bonds contribute to the rate limiting step.…”