A range of alpha-amino-, omega-amino-, alpha-guanidino-, and omega-guanidinoalkanephosphonic acids has been prepared for the purpose of studying their spectroscopic features and fungicidal activity. In addition, alpha-thioureido-octanephosphonic acid and thioureylene-1,1-bis(1-octanephosphonic acid) were isolated during the preparation of alpha-guanidino-octanephosphonic acid. P-31, H-1, and C-13 nmr spectral data which were obtained for solutions of the amino- and guanidino-compounds in D2O or D2O/D2SO4, and for the thioureido compounds in DMSO-d(6), are discussed together with previously reported data for the aminophosphonic types. FAB mass spectrometry generally gives strong pseudomolecular ions [MH](+) for the zwitterionic amino- and guanidino-compounds with relatively simple fragmentations. Fungicidal activity of the alpha-aminophosphonic acids was found to be greater than for the omega-amino compounds, with maximum activity at a chain length of three carbon atoms when used as a seed dressing for the control of Drechslera spp. Moderately good activity was shown by the thioureido compounds against a number of fungal organisms in vitro but the guanidino-compounds exhibited low activity.
