Aluminum Monocation Basicity and Affinity Scales

Abstract

The experimental aspects of the determination of thermochemical data for the attachment of the aluminum monocation Al(+) to neutral atoms and molecules are reviewed. Literature aluminum cation affinities (enthalpy scale) and basicities (Gibbs energy scale) are tabulated and discussed. Ab initio quantum chemical calculations at the G4 level on 43 adducts provide a consistent picture of the energetics of the adducts and their structures. The Al(+)-ligand bonding is analyzed in terms of natural bond orbital and atom-in molecule analyses. A brief comparison of the Al(+) basicity scales and other gas- phase cation basicities is presented.

Cationic Noncovalent Interactions: Energetics and Periodic Trends

“…Uncertainties in parentheses. b Reference for this row except as noted. C = threshold collision-induced dissociation, E = single temperature equilibrium, H = high-pressure temperature-dependent equilibrium, and K = kinetic method. c Relative free energy (E) from ICR equilibrium at 298 K, reanchored here and adjusted approximately to 0 K using the average value for H 0 – G 298 = 26.1 ± 2 kJ/mol from ref . d Relative free energy (E) from ICR equilibrium at 298 K adjusted to 0 K in ref . e Relative free energy (E) from ref anchored as discussed in ref and adjusted here from 298 to 0 K using information in ref . f Relative free energy (E) from refs and anchored here to D (Al + –CH 2 O) from ref and adjusted to 0 K using information calculated in ref . g Relative free energy (E) anchored to D (Fe + –C 2 H 4 ) from ref . …”

“…Uncertainties are listed in parentheses. A = radiative association kinetics, C = threshold collision-induced dissociation, ,,,,,,,,,,,,, E = single temperature equilibrium, ,,,,,,,− , H = high-pressure temperature-dependent equilibrium, ,,,, and P = photodissociation b Relative free energy from ICR equilibrium (E) at 373 K. ,, Adjusted to 0 K using information from ref . c Relative free energy from ICR equilibrium (E) at 298 K .…”

“… b Relative free energy from ICR equilibrium (E) at 373 K. ,, Adjusted to 0 K using information from ref . c Relative free energy from ICR equilibrium (E) at 298 K . Reanchored and adjusted to 0 K in ref . d Relative free energy from ICR equilibrium (E) at 298 K adjusted to 0 K using information in ref or . e Relative free energy from ICR equilibrium (E) at 298 K anchored as discussed in ref and adjusted here from 298 to 0 K using information in ref if possible. f Relative free energy from ICR equilibrium (E) at 298 K , anchored here to D (Al + –CH 2 O) from ref and adjusted to 0 K using information calculated in ref if possible. g Adjusted from relative free energies from ICR equilibrium (E) by symmetry number only . Anchored here to value for Mn + (C 6 H 6 ) from Table .…”

“…Anchored here to value for Mn + (C 6 H 6 ) from Table . Values would be 11 kJ/mol higher if anchored to Mn + (NH 3 ) in Table . h Relative free energy from ICR equilibrium (E), anchored and adjusted to 0 K in ref . i Relative free energy (E) anchored here to D (Al + –CH 2 O) from ref and approximately adjusted to 0 K by adding H 0 – G 298 = 28 ± 3 kJ/mol, determined from average of calculated corrections in ref . j From ref (C). Reevaluated in ref . k Feng and Gronert (K), unpublished as reported in ref . l Relative free energy from ICR equilibrium (E) at 373 K. ,, Adjusted approximately to 0 K by adding H 0 – G 373 = 35.4 ± 2.4 kJ/mol, determined from comparison of values in ref versus refs and .…”

“…In some measure, this is revealed by the many reviews that precede this one, to which the interested reader is referred for more detailed examinations of parts of the present opus. These include a general review in 1986 by Keesee and Castleman, examination of cation−π interactions by Dougherty, , a review of protonated systems by Meot-Ner, a review of our own work (largely metals), − reviews of individual metal cations interacting with ligandsLi + , , Cs + , Al + , and comprehensiveand a review concentrating on supramolecular chemistry…”