Interactions between phenothiazine drugs and metal ions. Part 2. Crystal and molecular structure of protonated trichloro[2-chloro-10-(3′-dimethylaminopropyl)phenothiazine-S]palladium(II), [Pd(cpzH)Cl3]; hydrogen-1 and carbon-13 nuclear magnetic resonance data for the chlorpromazine complexes [M(cpzH)Cl3](M = Pd or Pt)

The structure of the chlorpromazine complex [Pd(cpzH)Cl3] has been elucidated by single-crystal X-ray crystallography. Crystals are monoclinic, space group C2/c, Z= 8, in a unit cell with lattice parameters a= 29.757(9), b= 9.487(4), c= 16.184(6)A, β= 116.5(1)°. The structure has been solved using heavy-atom methods and refined by least squares to R= 0.056 (R′= 0.060) for 1 277 independent reflections collected by counter methods. Chlorpromazine is sulphur-bonded to a PdCl3 unit, the counter ion being a protonated nitrogen on the drug substituent. The side chain adopts an unusual conformation apparently to facilitate both intra- and inter-molecular hydrogen bonding. The n.m.r. data show that this conformation is maintained in the aprotic solvent NN-dimethylformamide.