The fumarate salts of the N-isopropyl-N-methyl derivatives of DMT and psilocin.

The solid-state structures of the salts of two substituted tryptamines, namely N-isopropyl-N-methyl-tryptaminium (MiPT) fumarate {systematic name: [2-(1H-indol-3-yl)eth-yl](meth-yl)propan-2-yl-aza-nium 3-carb-oxy-prop-2-enoate}, C14H21N2 +·C4H3O4 -, and 4-hy-droxy-N-isopropyl-N-methyl-tryptaminium (4-HO-MiPT) fumarate monohydrate {systematic name: [2-(4-hy-droxy-1H-indol-3-yl)eth-yl](meth-yl)propan-2-yl-aza-nium 3-carb-oxy-prop-2-enoate monohydrate}, C14H21N2O+·C4H3O4 -·H2O, are reported. Both salts possess a proton-ated tryptammonium cation and a 3-carb-oxy-acrylate (hydrogen fumarate) anion in the asymmetric unit; the 4-HO-MiPT structure also contains a water mol-ecule of crystallization. Both cations feature disorder of the side chain over two orientations, in a 0.630 (3):0.370 (3) ratio for MiPT and a 0.775 (5):0.225 (5) ratio for 4-HO-MiPT. In both extended structures, N-H⋯O and O-H⋯O hydrogen bonds generate infinite two-dimensional networks.