Mononuclear platinum(II) complexes coordinated by pyridyl nitronyl nitroxide radicals: structures and magnetic properties of trans-[Pt(NH 3) 2(NITpPy) 2](NO 3) 2 and cis-[PtCl 2(NIToPy) 2

Abstract

Crystal structures and magnetic properties of mononuclear Pt II complexes coordinated by pyridyl nitronyl nitroxide radicals, trans-[Pt(NH 3) 2(NITpPy) 2](NO 3) 2 (NITpPy=2-(4-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1 H-imidazolyl-1-oxyl 3-oxide) and cis-[PtCl 2(NIToPy) 2] (NIToPy=[2-(2-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1 H-imidazolyl-1-oxyl 3-oxide]) have been characterized. In both complexes, the radical ligands are square planar coordinated to the Pt II ion through the nitrogen atoms of the pyridine ring. Complex of cis-[PtCl 2(NIToPy) 2] has short non-bonding intramolecular distances between the Pt II center and the nitroxide oxygens of the radicals (Pt⋯O=3.31 Å), showing a pseudo octahedral coordination. Magnetic susceptibility of trans-[Pt(NH 3) 2(NITpPy) 2](NO 3) 2 obeys the Curie–Weiss law with a weak antiferromagnetic interaction ( θ=−1.4 K), and that of cis-[PtCl 2(NIToPy) 2] is fitted by a singlet–triplet model (2 J/ k B=−27.2 K, θ=−1.1 K). The intramolecular antiferromagnetic property in the latter complex can be ascribable to a through-space interaction between the radical moieties through the Pt II ion.