The formation of a C-H center dot center dot center dot pi bonded complex between halothane, CF3CHBrCl, and ethene has been studied in liquid krypton in the temperature range between 119 and 143 K, using infrared and Raman spectroscopy. The standard complexation enthalpy of the 1: 1 complex was measured to be -5.0(2) kJ mol (1). The stretching mode of the C-H bond involved in the formation of the complex was observed to red shift by 7.2(1) cm (1), while its intensity increased by a factor of 2.1(2). The results are compared with ab initio calculations at the MP2/6-311++G(d,p) and MP2/aug-cc-PVXZ (X = D, T and Q) levels. (C) 2008 Elsevier B.V. All rights reserved.