The theoretical calculation of the CC, CO and the CF 2 asymmetric stretching infrared intensities of the isoelectronic 1,1-C 2H 2F 2 and F 2CO molecules has resulted in large errors varying from 41.0 to 60.5 km mol -1 or 13.5% to 28.0% of their experimental intensities when using extended 6-311++G(3d,3p) basis set wave-functions at the Moller-Plesset 2 level. For this reason new theoretical intensity results are reported using wave-functions calculated with a large variety of basis sets at both the MP2 and QCISD levels. Accurate intensities were obtained with wave-functions formed from basis sets with polarization functions but without diffuse functions, 6-31G(d,p), 6-31G(2d,2p), 6-31G(3d,3p), 6-311G(d,p) and 6-311G(3d,3p) at both electron correlation levels. Best results for these bands were obtained with the 6-31G(2d,2p) wave-function at the QCISD level providing errors less than 10 km mol -1 and 3.4% of the experimental values. The rms errors for all the 1,1-C 2H 2F 2 and F 2CO intensities at this level are 12.3 and 6.5 km mol -1, respectively. These wave functions at both electron correlation levels also resulted in accurate values for the fundamental intensities of trans-C 2H 2F 2 and cis-C 2H 2F 2 with rms errors of less than 10 km mol -1. Theoretical calculations of the infrared intensities of the 1,1-C 2HDF 2 isotopomer indicate that the experimental determination of the CH symmetric stretching intensity of 1,1-C 2H 2F 2 is probably over-estimated owing to severe band overlap and/or Fermi resonance with the ν 2 + ν 3 combination band. © 2011 Elsevier B.V. All rights reserved.1009 4954Da Silva Jr., J.V., Faria, S.H.D.M., Haiduke, R.L.A., Bruns, R.E., (2007) J. Phys. Chem., 111, p. 515Faria, S.H.D.M., Da Silva Jr., J.V., Haiduke, R.L.A., Vidal, L.N., Bruns, R.E., (2007) J. Phys. Chem., 111, p. 7870Bruns, R.E., Bassi, A.B.M.S., (1975) J. Chem. Phys., 79, p. 1880Suto, E., Ramos, M.N., Bruns, R.E., (1993) J. Phys. Chem., 97, p. 6161Bader, R.F.W., (1990) Atoms in Molecules: A Quantum Theory, , Clarendon Press Oxford, UKHaiduke, R.L.A., Bruns, R.E., (2005) J. Phys. Chem. A, 109, p. 2680Hopper, M.J., Russell, J.W., Overend, J., (1968) J. Chem. Phys., 48, p. 3765Kagel, R.O., Powell, D.L., Overend, J., Ramos, M.N., Bassi, A.B.M.S., Bruns, R.E., (1982) J. Chem. Phys., 77, p. 1099Cramer, C.J., (2004) Essentials of Computational Chemistry, , second ed. Wiley Chichester, UKDa Silva Jr., J.V., Vidal, L.N., Vazquez, P.A.M., Bruns, R.E., (2010) Int. J. Quant. Chem., 110, p. 2029Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Montgomery Jr., J.A., Pople, J.A., (2004) GAUSSIAN03, Revision C.02, , Gaussian, Inc., Wallingford CT(1998) MORPHY98, A Program Written by P.L.A. Popelier with A Contribution from R.G.A. Bone, , UMIST, Manchester, England, EUVidal, L.N., Vazquez, P.A.M., (2003) Quim. Nova, 26 (4), p. 507Vidal, L.N., Vazquez, P.A.M., (2005) Int. J. Quant. Chem., 103 (5), p. 632Ward Jr., J.H., (1963) J. Am. Stat. Assoc., 58, p. 236McKean, D.C., Van Der Veken, B., Herrebout, W., Law, M.W., Brenner, M.J., Nemchick, D.J., Craig, N.C., (2010) J. Phys. Chem A, 114, p. 5728Silva, A.F., Da Silva Jr., J.V., Haiduke, R.L.A., Bruns, R.E., J. Phys. Chem. A, , dx.dói.org/10.1021/jp202929sGalabov, B., Yamaguchi, Y., Remington, R.B., Schaefer III, H.F., (2002) J. Phys. Chem. A, 106, p. 819Halls, M.D., Schlegel, H.B., (1998) J. Chem. Phys., 109, p. 10587Craig, N.C., Overend, J., (1969) J. Chem. Phys., 51, p. 1127Craig, N.C., Petersen, K.L., McKean, D.C., (2002) J. Phys. Chem. A, 106, p. 6358Kagel, R.O., Powell, D.L., Hopper, M.J., Overend, J., Ramos, M.N., Bassi, A.B.M.S., Bruns, R.E., (1984) J. Phys. Chem., 88, p. 521Kagel, R.O., Powell, D.L., Overend, J., Ramos, M.N., Bassi, A.B.M.S., Bruns, R.E., (1983) J. Chem. Phys., 78, p. 7029Bruns, R.E., Bassi, A.B.M.S., (1975) J. Chem. Phys., 62, p. 3235Edgell, W.F., Byrd, W.E., (1950) J. Chem. Phys., 18, p. 892Smith, D.C., Nielson, J.R., Claassen, H.R., (1950) J. Chem. Phys., 18 (326), p. 812Kagel, R.O., Ph.D. Thesis, University of MinnesotaJiang, H., Appadoo, D., Robertson, E., McNaughton, D., (2002) J. Comput. Chem., 23, p. 1220