Dipole effects on cation-pi interactions: absolute bond dissociation energies of complexes of alkali metal cations to N-methylaniline and N,N-dimethylaniline.
Threshold collision-induced dissociation of M (+)( nMA) x with Xe is studied using guided ion beam mass spectrometry, where nMA = N-methylaniline and N, N-dimethylaniline and x = 1 and 2. M (+) includes the following alkali metal cations: Li (+), Na (+), K (+), Rb (+), and Cs (+). In all cases, the primary dissociation pathway corresponds to the endothermic loss of an intact nMA ligand. The primary cross section thresholds are interpreted to yield 0 and 298 K bond dissociation energies (BDEs) for ( nMA) x-1 M (+)-( nMA) after accounting for the effects of multiple ion-neutral collisions, the internal and kinetic energy distributions of the reactants, and the dissociation lifetimes. Density functional theory calculations at the B3LYP/6-31G* level of theory are used to determine the structures of these complexes, which are also used in single-point calculations at the MP2(full)/6-311+G(2d,2p) level to determine theoretical BDEs. The results of these studies are compared to previous studies of the analogous M (+)(aniline) x complexes to examine the effects of methylation of the amino group on the binding interactions. Comparisons are also made to a wide variety of cation-pi complexes previously studied to elucidate the contributions that ion-dipole, ion-induced-dipole, and ion-quadrupole interactions make to the overall binding.
Hallowita
Nuwan
N
Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA.
Carl
Damon R
DR
Armentrout
P B
PB
Rodgers
M T
MT
D000814:Aniline Compounds / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D008672:Metals, Alkali / Q000737:chemistry*; D008956:Models, Chemical; D009942:Organometallic Compounds / Q000737:chemistry*; D013816:Thermodynamics
D000814:Aniline Compounds; D002412:Cations; D008672:Metals, Alkali; D009942:Organometallic Compounds; C015157:N,N-dimethylaniline; C021313:methylaniline