Origins of relative acidity: First and second period hydrides

✍ Scribed by Laidig, Keith E.; Streitwieser, Andrew

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 806 KB
• Volume: 17
• Category: Article
• ISSN: 0192-8651
• DOI: 10.1002/(sici)1096-987x(19961130)17:15<1771::aid-jcc7>3.0.co;2-m

✦ Synopsis

The origins of the trends of relatively acidity across and between the first and second period hydrides (BH,, CH,, NH,, H,O, HF, AlH,, SiH,, PH,, H,S, and HC1) were investigated using molecular and subsystem quantum mechanics at the Hartree-Fock (HF)/6-31 + + G**//HF/6-31 + + G** level of theory. The total deprotonation energies, A Eacidr are interpreted in terms of three component processes: A El; deprotonation without electronic and nuclear relaxation; A E,, electronic relaxation within the acid geometry; and A E,, nuclear relaxation. A E, is given from the electrostatic potential at the acidic proton, A El + A E,( = A E*) is given from the calculated energy of the conjugate anion at the acid geometry. The increased acidity across a given period is shown to be already mostly an inherent property of the acid.