The two-dimensional algebraic model for degenerate bending modes has been extended to include interaction terms with stretching modes and to provide a detailed description of the dipole operator for linear molecules. An algebraic mixed model is used to investigate, for the first time, the absolute infrared intensities in (C2H2)-C-12 up to 10 000 cm(-1). Intensities of hitherto unmeasured vibrational bands are also given.