Synthesis, characterization, and representative crystal structure of lipophilic platinum(II) (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, but yrate, pentanoate, hexanoate, heptanoate, octanoate, nonanoate, decanoate, undecanoate, laureate, tridecanoate, myristate, pentadecanoate, palmitate, or heptadecanoate; and LL = oxalate, or tartronate) were synthesized and ch aracterized by elemental analysis, IR, C-13 NMR, and Pt-195 NMR. In additio n, the crystal structure of a representative complex [Pt-II(HPIP)(pentadeca noate)(2)]. was determined by X-ray diffraction. The crystals were monoclin ic, 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 colle cted, and the structure refined to R1 = 0.0522 and wR2 = 0.1333. The slight ly distorted square plane of the platinum included the amino groups of the HPIP molecule in cir positions and oxygens from two monodentate pentadecano ates. 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 la ttices together.