Cytotoxicity and Structural Analyses of 2, 2′‐Bipyridine‐, 4, 4′‐Dimethyl‐2, 2′‐bipyr­idine‐ and 2‐(2′‐Pyridyl)quinoxalineplatinum(II) Complexes (Eur. J. Inorg. Chem. 25/2015). Issue 25 (September 2015)