Platinum–acetylene or –ethylene complexes with bridging or chelating ethylenediamine derivatives

Abstract

The reaction intermediates of K[Pt(ac)X3] with ethylenediamine and its N-substituted derivatives have been studied in water and organic solvents. The general reaction is [Formula: see text]where ac = (CH3)2C(Y)C≡CC(Y)(CH3)2, en = ethylenediamine, Y = OH, OCH3, and X = Cl, Br. The five-coordinate intermediates 2 are isolated and characterized from conductivity data, molecular weight determinations, and infrared, nuclear magnetic resonance (n.m.r.), and ultraviolet (u.v.)-visible absorption spectra. The stability of complexes 2 (see equation above) in terms of alkyl substitution of the NH2 groups is approximatelyenMe4 > enMe2Et2 > enH2Me2 > enwhere enMe4 = (CH3)2N(CH2)2N(CH3)2, enMe2Et2 = CH3C2H5N(CH2)2NC2H5CH3, enH2Me2 = CH3HN(CH2)2NHCH3, enEt4 = (C2H5)2N(CH2)2N(C2H5)2. In contrast to these reactions, the Zeise salt, K[PtC2H4Cl3], reacts with ethylenediamines and gives only stable, bridged compounds of the formula (PtC2H4Cl2)2(en). Bridged compounds, (Pt(ac)Cl2)2(en), are also obtained with K[Pt(ac)Cl3], but only in the presence of a large excess of KCl in the reaction solutions.