New Compounds of the ThCr2Si2-Type and the Electronic Structure of CaM2Ge2 (M: Mn–Zn)

Two new molybdenyl iodates, K2MoO2(IO3)4 (1) and BETA-KMoO3(IO3) (2), have been prepared from the reactions of MoO3 with KIO4 and NH4Cl at 180°C in aqueous media. The structure of 1 consists of molecular [MoO2(IO3)4]2- anions separated by K+ cations. The Mo(VI) centers are ligated by two cis-oxo ligands and four monodentate iodate anions. Both terminal and bridging oxygen atoms of the iodate anions form long ionic contacts with the K+ cations. BETA-KMoO3(IO3) (2) displays a two-dimensional layered structure constructed from 2INFINITY[(MoO3(IO3)]1- anionic sheets separated by K+ cations. These sheets are built from one-dimensional chains formed from corner-sharing MoO6 octahedra that run along the b-axis that are linked together through bridging iodate groups. K+ cations separate the layers from one another and form long contacts with oxygen atoms from both the iodate anions and molybdenyl moieties. Crystallographic data: 1, monoclinic, space group C2/c, a=12.8973(9) ?, b=6.0587(4) ?, c=17.694(1) ?, BETA=102.451(1)°, Z=4, MoKALPHA, =0.71073, R (F)=2.64% for 97 parameters with 1584 reflections with I>2SIGMA(I); 2, monoclinic, space group P21/n, a=7.4999(6) ?, b=7.4737(6) ?, c=10.5269(8) ?, BETA=109.023(1)°, Z=4, MoKALPHA, LAMBDA=0.71073, R(F)=2.73% for 83 parameters with 1334 reflections with I>2SIGMA(I).