Abstract: | The IR- and RAMAN -spectra are reported from OP(OCH3)2Cl, OP(OCH3)Cl2, SP(OCH3)Cl, SP(OCH3)Cl2. The assignement to the fundamental vibration is given and all Valence-force-constants are calculated. With increasing number of chlorine atoms decrease f P? OCH3 and f P? Cl. In the contrary, f O? P and f S? P increase. Here the influence of decreasing electro negativity is compensated by the change from an element of the first period of eight elements to an element of the second period. |