Synthesis, characterization, and representative crystal structure of lipophilic platinumII (homopiperazine)carboxylate complexes

A series of new lipophilic platinum(II) complexes of the type [Pt(HPIP)L-2] and [Pt(HPIP)L] (where HPIP = homopiperazine; L = acetate, propionate, butyrate, pentanoate, hexanoate, heptanoate, octanoate, nonanoate, decanoate, undecanoate, laureate, tridecanoate, myristate, pentadecanoate, palmitate, or heptadecanoate; and LL = oxalate, or tartronate) were synthesized and characterized by elemental analysis, IR, C-13 NMR, and Pt-195 NMR. In addition, the crystal structure of a representative complex [Pt-II(HPIP)(pentadecanoate)(2)]. was determined by X-ray diffraction. The crystals were monoclinic, space group P2(1)/c, with a = 28.212(6) Angstrom, b = 3.661(3) Angstrom, c = 10.218(2) Angstrom, and Z = 4. A total of 3940 reflections were collected, and the structure refined to R1 = 0.0522 and wR2 = 0.1333. The slightly distorted square plane of the platinum included the amino groups of the HPIP molecule in cir positions and oxygens from two monodentate pentadecanoates. The HPIP molecule was in a boat conformation and formed five- and six-member chelating rings with platinum. Together, these molecules formed an intricate network of intermolecular hydrogen bonds that held the crystal lattices together.