Reactions of Niobium and Tantalum Hexanuclear Halide Clusters with Cadmium(II) Halides. Diamagnetic and Paramagnetic Clusters with Semiconducting Properties

Abstract The diamagnetic [Ta 6 Cl 12 (H 2 O) 6 ][CdCl 2 X 2 ]·12H 2 O (X = Br, I) 1 , 2 and [M 6 Br 12 (H 2 O) 6 ][CdBr 2 X 2 ]·12H 2 O (M = Nb, Ta; X = Cl, Br, I) 3–8 clusters as well as paramagnetic [(Ta 6 Cl 12 )Cl(H 2 O) 5 ][CdBr 4 ]·6H 2 O 9 have been isolated. The crystal structures have been determined for [Nb 6 Br 12 (H 2 O) 6 ][CdBr 4 ]·12H 2 O 4 , [Ta 6 Br 12 (H 2 O) 6 ][CdBr 4 ]·12H 2 O 7 and [(Ta 6 Cl 12 )Cl(H 2 O) 5 ][CdBr 4 ]·6H 2 O 9 . Octahedral cluster cations [M 6 Br 12 (H 2 O) 6 ] 2+ in 4 , 7 and [(Ta 6 Cl 12 )Cl(H 2 O) 5 ] 2+ in 9 , together with [CdBr 4 ] 2− anion as discrete units are main structural building blocks. The crystal packing of the cations and anions in a three-dimensional network in 4 and 7 is realized via hydrogen bonds involving crystal and coordinated water molecules and Br − atoms from [CdBr 4 ] 2− anions. The paramagnetic cluster 9 displays the quazionedimensional magnetic properties with intrachain antiferromagnetic interaction J = 68 K and the interchain interaction J’ = 21 K. All compounds show semiconducting properties. The respective activation energies, E a1 = 0.23 eV and E a2 = 0.19 eV (the same values for 7 and 9 ) have been found.