1. Mulliken Center for Theoretical ChemistryInstitute of Physical and Theoretical ChemistryRheinische Friedrich-Wilhelms-Universität Bonn Beringstraße 4 53115 Bonn Germany
2. Experimental work was done in: Chemical EngineeringUniversity of KwaZulu-Natal 238 Mazisi Kunene Rd, Glenwood Durban 4001 South Africa