The 1:1 complexes of TiCl4 with PH3 and AsH3 have been characterized in argon matrices. Intense spectral features in the 400-500 cm(-1) region were assigned to Ti-Cl antisymmetric stretching modes in each complex, shifted from the parent mode near 500 cm(-1) while the bending modes of coordinated PH3 and AsH3 shifted 15-70 cm(-1). The Ti-Cl stretching modes of the complexes shifted with different bases; these shifts correlate with the intrinsic basicity of each base.