Infrared spectra of N,N',N''-triphenylguanidine (PhNH) 2 C NPh (Ph 3 G) and its imine nitrogen coordinated Pd(II) complexes (trans-Pd(Ph 3 G) 2 Cl 2 and [Pd(Ph 3 G) 4 ](ClO 4 ) 2 ) have been studied in the 4000-150cm - 1 frequency range. Complete equilibrium geometry of the Ph 3 G has been determined by ab initio calculations employing two different levels of the theory: HF/6-31G * and DFT (B3LYP/6-31G * ). The theoretical predictions are discussed and compared with experimental results were appropriate. A complete vibrational assignment of the solid-state IR spectrum of Ph 3 G was performed on the basis of normal coordinate analysis of a single molecule. The coordination of Ph 3 G to Pd(II) through imine nitrogen has been confirmed by study of the IR spectrum of trans-Pd(Ph 3 G) 2 Cl 2 complex. On the basis of the IR study of the ligand and its Pd(II) complexes a mono-dentate coordination of the ligands in the [Pd(Ph 3 G) 4 ](ClO 4 ) 2 complex was suggested.