3d-Metal derivatives of the [CuI(SO3)4]7− ion: structure and magnetism

Abstract

The Cu(SO₃)₄⁷⁻ anion, which consists of a tetrahedrally coordinated Cu(I) centre coordinated to four sulfur atoms, is able to act as a multidentate ligand in discrete and infinite supramolecular species. The slow oxidation of an aqueous solution of Na₇Cu(SO₃)₄ yields a mixed oxidation state, 2D network of composition Na₅{[Cu^II(H₂O)][Cu^I(SO₃)₄]}·6H₂O. The addition of Cu(II) and 2,2′-bipyridine to an aqueous Na₇Cu(SO₃)₄ solution leads to the formation of a pentanuclear complex of composition {[Cu^II(H₂O)(bipy)]₄[Cu^I(SO₃)₄]}⁺; a combination of hydrogen bonding and π–π stacking interactions leads to the generation of infinite parallel channels that are occupied by disordered nitrate anions and water molecules. A pair of Cu(SO₃)₄⁷⁻ anions each act as a tridentate ligand towards a single Mn(II) centre when Mn(II) ions are combined with an excess of Cu(SO₃)₄⁷⁻. An anionic pentanuclear complex of composition {[Cu^I(SO₃)₄]₂[Fe^III(H₂O)]₃(O)} is formed when Fe(II) is added to a Cu⁺/SO₃²⁻ solution. Hydrated ferrous [Fe(H₂O)₆²⁺] and sodium ions act as counterions for the complexes and are responsible for the formation of an extensive hydrogen bond network within the crystal. Magnetic susceptibility studies over the temperature range 2–300 K show that weak ferromagnetic coupling occurs within the Cu^II containing chains of Na₅{[Cu^II(H₂O)][Cu^I(SO₃)₄]}·6H₂O, while zero coupling exists in the pentanuclear cluster {[Cu^II(H₂O)(bipy)]₄[Cu^I(SO₃)₄]}(NO₃)·H₂O. Weak Mn(II)–O–S–O–Mn(II) antiferromagnetic coupling occurs in Na(H₂O)₆{[Cu^I(SO₃)₄][Mn^II(H₂O)₂]₃}, the latter formed when Mn was in excess during synthesis. The compound, Na₃(H₂O)₆[Fe^II(H₂O)₆]₂{[Cu^I(SO₃)₄]₂[Fe^III(H₂O)]₃(O)}·H₂O, contained trace magnetic impurities that affected the expected magnetic behaviour.