Does cation break the cyano bond? A critical evaluation of nitrile-cation interaction.
DFT and G4 results reveal that cations display the following trends in imparting its positive charge to acrylonitrile; H⁺ > Li⁺ > Na⁺ > K⁺ for group I and Be²⁺ > Mg²⁺ > Ca²⁺ for group II. Solvation by water molecules and interaction with cation make the cyano bond more polarized and exhibits ketene-imine character. Bond order in nitrile-cation complexes has been predicted based on the s character of the covalent bond orbitals. Mulliken, CHELPG, and NPA charges are in good agreement in predicting positive charge buildup and GIAO nuclear deshileding on C1. G4 enthalpies show that Mg²⁺ is more strongly bound to acrylonitrile than to acetonitrile by 3 kcal mol⁻¹, and the proton affinity of the former is higher by 0.8 kcal mol⁻¹. G4 enthalpies of reductions support prior experimental observation that metalated conjugated nitriles show enhanced reactivity toward weak nucleophiles to afford Michael addition products.
Department of Chemistry, Faculty of Science Building, University of Malaya, 50603, Kuala Lumpur, Malaysia, pmwoi@um.edu.my.
Pei Meng
PM
Woi
Maizathul Akmam A
MA
Bakar
Ahmad Nazmi
AN
Rosli
Vannajan Sanghiran
VS
Lee
Mohd Rais
MR
Ahmad
Sharifuddin
S
Zain
Yatimah
Y
Alias
D000097:Acetonitriles / Q000737:chemistry; D000181:Acrylonitrile / Q000737:chemistry*; D066241:Carbon-13 Magnetic Resonance Spectroscopy; D002412:Cations / Q000737:chemistry*; D003198:Computer Simulation; D004735:Energy Transfer; D005740:Gases; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011522:Protons; D012997:Solvents / Q000737:chemistry; D055672:Static Electricity; D013329:Structure-Activity Relationship; D014732:Vibration; D014867:Water / Q000737:chemistry
D000097:Acetonitriles; D002412:Cations; D005740:Gases; D011522:Protons; D012997:Solvents; D014867:Water; D000181:Acrylonitrile; C032159:acetonitrile