In this article we describe the synthesis of TRIPA, dodecamethyl bisimidotriphosphoramide (C 12 H 36 N 7 O 3 P 3 ) and of its complexes with various lanthanide-nitrates. Five types of complexes have been isolated according to the compositions, X-ray diffraction patterns and IR spectra. 1. M(N0 3 ) 3 (TRIPA) 3 (acetone) M = La, Pr, Nd, 2. M(N0 3 ) 3 (TRIPA) M = Y, 3. M(N0 3 ) 3 (TRIPA) 2 (nitromethane) M = Er, Y, 4. M(N0 3 ) 3 (TRIPA) 2 (acetone) M = Sm, Gd, Dy, Er, Y (type I), 5. M(N0 3 ) 3 (TRIPA) 2 (acetone) M = Y (type II). The yttrium complexes, type I and II, are isomeric. IR spectra are given together with the NMR spectra. It is concluded that in all complexes the three TRIPA oxygens are coordinated, except in group 1. The nitrate groups in group 2 to 5 are involved in the coordination, particularly in the type 2 complex, where there are bidentate nitrate groups. There seems to be a difference in the conformation of the TRIPA molecules between the free ligand, the complexes in group 1, in group 2 and in group 3, 4, 5 Hygroscopic TRIPA can be easily confused with a stable mono-hydrate, TRIPA · H 2 O.