Methylacetylene and tert-butylacetylene as IR-probe molecules for the characterisation of basicity

Methylacetylene (MA) and tert-butylacetylene (TA) were used as probe molecules in infra-red spectroscopy for characterisation of the basicity of MgO. Reference experiments with SiO2 showed the formation of a pi -complex via the C equivalent toC bond of MA or TA with the weakly acidic silanol groups. The adsorption model proposed for MA and TA on MgO involves a H-bonding adsorption interaction of the probe molecule via the acidic equivalent to CH end with the basic O2- sites with a possible simultaneous interaction of the C equivalent toC bond with OH groups which are preferentially located at corners on the MgO surface. (C) 2001 Elsevier Science BN. All rights reserved.