Behaviour of diamine-af-dibromo-dinitroplatinum(IV) complexes and the adduct ac-dinitro-bd-bis(pyridine)platinum(II)–boron trifluoride in acidic solutions

Abstract

Octahedral diamine-af-dibromo-dinitroplatinum(IV) complexes [diamine =de- and ce-bis(pyridine), bc-(2,2′-bipyridine), and ce-bis(triethylphosphine)] have been prepared from the corresponding square-planar platinum(II) complexes by oxidative addition with bromine. Kinetic studies of the replacement of the first nitro-group from the platinum(IV) complexes in aqueous sulphuric acid and sulphuric acid–acetic acid solutions show that the complexes are difficult to protonate, i.e. the protonated forms are very strong acids. The rate constant for the release of the first nitro-group has been measured and correlated with acidity function and other parameters. The mechanism of these reactions is discussed. Preliminary studies of the preparation and reactivity of a platinum(II) complex, in which an axial position is occupied by a boron trifluoride acceptor molecule, are also reported.