a semiempirical study of some clavulanic acid derivatives in relation to their activity as betalactamase inhibitors clavulanic acid and some of its derivatives are inhibitors of betalactamases and hence enhance the activity of antibiotics such as cephaloridine amoxycillin and ampicillin against betalactamaseproducing bacteria several empirical structureactivity relationships have been proposed for these compounds bearing these findings in mind we have carried out a semiempirical structural study on clavulanic acid and twelve of its derivatives lacking the carboxyl group we relate our results to the available activity data focusing on features such as planarity at the n atom charge distribution and the orientation of the substituents all of which are related to the activity of these systems