Rectangular tetragadolinium complex ion with a ground S=27/2 state containing bis(dimethylglyoximato)copper(II) as a ferrimagnetic exchange coupler

Pentanuclear [Cu(dmg)(2){Gd(hfac)(2)}(4)(AcO)(4)](Ph4P)(2) (1) (dmg = dimethylglyoximate dianion; hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) containing a central copper(II) and four peripheral gadolinium(III) ions was prepared and the crystal structure was determined by X-ray diffraction. Magnetic measurements on 1 revealed high ground spin multiplicity, as expected regardless of the sign of magnetic Cu...Gd coupling through N-O bridges. The ground state was suggested to be S-total = 27/2 with the exchange parameter 2J/k(B) = -2.9(2) K between the Gd and Cu ions. The antiferromagnetic coupling is operative owing to the largely distorted Gd-O-N-Cu bridges. (C) 2003 Elsevier B.V. All rights reserved.