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 Stotal=27/2 with the exchange parameter 2J/kB=−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.