Abstract The bisamide complex trans-[PtCl 2HN=C(OH)Bu t 2] ( 1) has been prepared by hydrolysis of dichlorobis(tertiary-butylnitrile)-platinum(II) and characterized via single crystal X-ray diffraction. The complex crystallizes in the Pbcn (No. 60) space group with the cell parameters a = 11,.692(2), b = 22.214(3) and c = 18.515(2) A ̊ . Twelve complex molecules are present in the cell where triplets of the are stabilized by intermolecular hydrogen bonds involving N, Cl and O atoms. The structure has a strict similarity with that previously reported (D.B. Brown, R.D. Burbank and M.B. Robin, J. Am. Chem. Soc., 91 (1969) 2895) (the refinement, however, showed all the non-H atoms and converged to R = 0.0471 for 1003 observed reflections ( F b > 6 σ( F e)) in the present work, whereas the structure analysis of the previous work did not show most of the atoms of a molecule in the asymmetric unit and the refinement converged to R = 0.107 for 2047 observed reflections) and proposed to contain, besides the yellow bisamide ( 1 ∼ 70%), also a second yellow material ( II. ∼ 20%) and a third blue material ( III. ∼ 10%). The latter two had an analytical composition similar to that of the first one and were formulated as isomeric dichlorobis(amidato)platinum(IV) species. The mixed amidenitrile species trans-[PtCl 2[HN=C(OH)Bu t)(NCBu t)] ( 2 has also been characterized. It has NMR signals coincident with those of compound II, its space group and cell parameters are very close to those of 1, and it has a tendency to cocrystallize with 1 in the molar ratio 2:1 in favor of 2. The geometry of the amide ligands in the enol tautomeric form appears to be ideal for favoring the face-to-face association of platinum units stabilized by interfacial hydrogen bonds. In the case of cis geometry (corresponding cis isomer of 1), platinum dimers with an intermetallic distance of 3.165(1) Å were formed: in contrast, in the case of trans geometry (compound 1 presently investigated) platinum triplets with an intermetallic distance of 3.668(1) Å were established. In both cases the preferred conformation is staggered and the shortest distance between platinum atoms in different dimers ( cis isomer) or triplets ( trans isomer) is in excess of 4.17 Å. Therefore, a special role of the coordination geometry appears to be in determining the mode of association of platinum monomers in oligomers.