cis-Diammine(glycolato-κ2 O 1,O 2)platinum(II)

The reaction of cis-[Pt(NO3)2(NH3)2] and sodium glycolate yielded the title compound, [Pt(C2H2O3)(NH3)2]. The PtII atom, coordinated by two N atoms of ammine and two O atoms of the carboxylate and oxido groups of the glycolate ligand, is in a square-planar environment. In the crystal structure, molecules are connected by intermolecular N—H⋯O hydrogen bonds, forming a three-dimensional network.


Related literature
The title compound is a second-generation platinum derivative that has an antitumour activity comparable to that of cisplatin, one of the most effective anti-cancer drugs for testicular, lung, bladder and other carcinomas, but which is less toxic to the kidney, see: Inuyama et al. (1992); Kameyama et al. (1990); Noda et al. (1992); Taguchi et al. (1992); Yamamoto et al. (2000). For related structures, see: Yuge & Miyamoto (1998); Griffith et al. (2007).
Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL. Cis-diamminedichloro-platinum(II) (cisplatin) is one of the most effective anti-cancer drugs for testicular, lung, bladder and other carcinomas. However, the clinical usefulness of this drug has frequently been limited by serious nephrotoxicity and gastrointestinal toxicity and the development of acquired resistance. In an attempt to overcome these drawbacks of cisplatin, numerous analogues have been prepared and evaluated in a search for alternative active agents. Among these compounds, the title compound, cis-diammine(glycolato-o,o')platinum(II), is a second-generation platinum derivative that has an antitumour activity comparable to cisplatin but is less toxic to the kidney (Kameyama et al.,1990), as seen in preclinical experiments.
It produced promising response rates in phase II trials for treatment of squamous cell carcinoma arising from the head and neck (Inuyama et al.,1992), lung (Yamamoto et al.,2000), oesophagus (Taguchi et al.,1992), and uterine cervix (Noda et al., 1992). For related structures see: (Yuge & Miyamoto, 1998;Griffith et al., 2007) The compound forms a hydrogen-bonded structure (Fig. 2), in which one of the H atoms of ammonia serves as a donor to the O atom of the glycollate of an adjacent molecule and these hydrogen-bond interactions give rise to a three-dimensional network.

Experimental
Cis-[Pt(NO 3 ) 2 (NH 3 ) 2 ] (2.0 nmol) was dissolved in 50 ml water and sodium glycolate (2.0 mmol in 50 ml water) was added thereto. The mixture was adjusted to pH=7 with NaOH solution and stirred at 323k for 3 h. The solution was condensed at 313k under reduced pressure to 5 ml, then a yellow crystalline product was precipitated. The compound was crystallized from water to obtain crystals suitable for X-ray structure analysis.

Refinement
All H atoms were initially located in a difference Fourier map. The H atoms bonded to carbon and nitrogen were placed at calculated positions (C-H = 0.97Å and N-H = 0.89 Å) and were included in the refinement in the riding model approximation, with U iso (H) = 1.2Ueq(C), U iso (H) = 1.5Ueq(N). Fig. 1. The molecular structure of title complex with the atomic labeling scheme. Displacement ellipsoids are drawn at the 30% probability level.