Crystalline adducts of zinc and copper(II) dithiocarbamate (Dtc) complexes with dialkylamines [M(NHR′2)(S2CNR2)2] (M = Zn, 63Cu, 65Cu; R = CH3, C2H5, or R2 = (CH2)4O; R′ = C2H5, C3H7) have been preparatively isolated. The structures and spectral properties of the adducts have been studied by EPR and 13C and 15N MAS NMR. Chemisorption of bases on powders of dinuclear dithiocarbamates leads to their dissociation into monomeric adducts. Computer simulation demonstrates that the experimental EPR spectra of isotope-substituted copper(II) adducts have an individual character. The geometry of the copper polyhedra is intermediate between a trigonal bipyramid (TBP) and a tetragonal pyramid (TP). The TBP and TP contributions have been quantified based on EPR data. 13C and 15N MAS NMR data show that the Dtc ligands incorporated into the zinc adduct molecule are structurally nonequivalent. The dependence of the isotropic 15N chemical shifts of the Dtc groups on the alkyl substituents at the nitrogen atom is interpreted based on the concept of joint manifestation of the (+)inductive effect of the alkyl substituents and the mesomeric effect of the Dtc groups.