A group of new selenite-chlorides of strontium and d-metals (Co,Ni): Synthesis, thermal behavior and crystal chemistry

The new selenite-chlorides with composition Sr3(SeO3)2Cl2 (I) and Sr2M(SeO3)2Cl2 (M=Co, Ni (II and III)) were obtained. They crystallize in monoclinic system I: space group C2/m, a=13.203(2) Å, b=5.5355(8) Å, c=6.6170(10) Å, β=95.89(1)°, Z=2; II Space group P21/n, a=5.3400(10) Å, b =6.4279(6) Å, c=12.322(1) Å, β=92.44(1)°, Z=2; III: space group P21/n, a=5.3254(11) Å, b=6.4363(13) Å, c=12.197(2), β=92.53(3)°, Z=2. All three compounds are constructed in the same manner. Sr polyhedra form infinite layers, which are interconnected into a 3D framework by means of Sr polyhedra in the case of I or Co and Ni polyhedra in the case of II and III. Se atoms are situated inside the channels of the 3D framework. The topological analysis of ELF for I confirmed that the lone electron pairs of SeO3 groups are located inside these channels.