The incorporation of low levels of Mn(II) (Mn/Alsimilar to0.001) into five aluminophosphate zeotypes was studied by high-field echo-detected EPR, and by P-31 and H-1 electron-nuclear double resonance (ENDOR) spectroscopies. The zeotype structures investigated-SOD, AEL; AFI, SBS, and SBT-cover. a variety of channel morphologies, and span a range of framework densities. The highly resolved EPR spectra could distinguish between two types of Mn with different 55 Mn hyperfine couplings in structures containing more than one T site. Mims and Davies P-31 ENDOR spectra, recorded at a field set to one of the \-1/2, m(l)> --> \+1/2, M-l> Mn-55 hyperfine components consist of a symmetric doublet, with a splitting in the range of 5-8 MHz. The large open structures showed smaller couplings than the denser morphologies. A similar IT hyperfine was also detected for Fe(III) incorporated into aluminophosphate zeotype with the SOD structure. Variations in the H-1 ENDOR spectra of the various Mn(II) substituted zeotypes, particularly in the relative intensity of the H-1 matrix line, were detected as well. These ENDOR results indicate a common mechanism of framework substitution in which Mn(II) and Fe(III) are replacing Al (or Mg). Moreover, the spectra serve as a probe for the differences in the local environment and bonding topology of these substituted framework sites. A qualitative interpretation of the P-31 ENDOR data is provided, based on, relevant crystallographic information, and the H-1 ENDOR signals are partially attributed to the interactions with the templates occluded in the zeotype cages. To further relate the isotropic P-31 hyperfine couplings to structural properties, DFT methods were employed for cluster model optimizations and hyperfine coupling constants calculations. Geometry optimizations of substituted rings, derived from the SOD and AEL framework structures, indicate considerable distortions of the coordination environment of framework Mn as compared to Al. A systematic study of the hyperfine interactions of a series of model structures containing tetrahedral and octahedral Mn(II) show that both Mn-O-bond lengths and Mn-O-P bond angles contribute significantly to the variation in the isotropic and anisotropic P-31 hyperfine coupling.