The second-order nonlinear optical effects such as second harmonic generation (SHG) and linear electrooptics (LEO) in the middle infrared spectral range (5-15 mum) are experimentally observed for the first time. We have found that the novel As2Te3-BaBr2-BiCl2 chalcogenide glasses, possessing transmission windows within the 3-45 mum spectral range, have both photoinduced SHG equal to 0.0012 pm/V and comparable values of photoinduced electrooptics effect at wavelength of excitation (lambda =10.6 mum). The photoinduced anharmonic electron-phonon interaction play the major role in the observed phenomena. A good correlation between the IR-induced nonlinear optical susceptibilities and the photoinduced anharmonic electron-quasi-phonon interactions is demonstrated. The pump-probe experiment shows that the intensity-dependent maximum of the LEO is shifted towards the higher delaying times comparing with the SHG ones. Comparison of theoretical simulations with experimental measurements indicate dominant role of the electron-phonon anharmonic subsystem in the observed effects.