The versatile chemistry and non-centrosymmetric crystal structures of salt-inclusion vanadate hybrids

Three unique structure types of the vanadate-based mixed-metal oxide systems (salt)·MnII-Vv-O and (salt)·CuII-Vv-O are presented, with a focus on the role of the asym. vanadate units. Lattice parameters were obtained for (CsCl)2Mn(VO3)2, (CsBr)2Mn(VO3)2, (RbCl)2Mn(VO3)2, (CsCl)2Cu(VO3)2, (CsCl)Mn2(V2O7), (KCl)2Cu(VO3)2, (RbCl)2Cu(VO3)2 and (CsBr)2Cu(VO3)2. The two structure types found in the (AX)2M-(VO3)2 series differ in the propagation direction of the metavanadate chains which is thought to be due to the presence (or absence) of a Jahn-Teller distortion of the metal (d9 Cu2+ vs. d5 Mn2+) ion