Crystal structure and magnetic properties of the coupled spin dimer compound SrCu2(TeO3)2Cl2

Single crystals of the strontium copper tellurium oxochloride SrCu2(TeO3)2Cl2 were synthesized via solid-gas reactions in sealed evacuated silica tubes. The compound crystallizes in the monoclinic system, space group P21, a=7.215(2), b=7.2759(15), c=8.239(2) Å, β=96.56(4)°, Z=2. The building units are [SrO6Cl2] irregular polyhedra, [CuO4] and [CuO3Cl] square planes, [TeO3E] tetrahedra and [TeO3+1E] trigonal bipyramids; E being the 5s2 lone pair of Te(IV). The Cu atoms can be regarded as forming a chain of weakly connected dimers. The magnetic susceptibility of the compound shows a broad maximum typical for antiferromagnetic spin fluctuations with a non-magnetic ground state. A Heisenberg spin model with coupled s=1/2 dimers leads to a satisfactory fitting of the experimental data.