![Author ORCID: We display the ORCID iD icon alongside authors names on our website to acknowledge that the ORCiD has been authenticated when entered by the user. To view the users ORCiD record click the icon. [opens in a new tab]](https://chemrxiv.org/engage/assets/public/chemrxiv/images/logos/orcid.png)
Abstract
Polycrystalline and single crystal specimens of the new quaternary phase MgPr9Mo16O35 were synthesized by direct solid-state reaction. MgPr9Mo16O35 presents a monoclinic unit cell (S.G. C2/m; a = 18.3422 (3) Å, b = 8.6188 (1) Å, c = 9.7276 (4) Å, = 101.9680 (4) and Z = 2). Its crystal structure was solved on a single-crystal by X-ray diffraction and refined to the final values R1 = 0.0281 and wR2 = 0.0473 (3903 independent reflections and 101 variables). For a comparative study the crystal structure of LiPr9Mo16O35 was also determined (a = 18.3422 (3) Å, b = 8.6188 (1) Å, c = 9.7276 (4) Å,= 101.9680 (4) and Z = 2; R1 = 0.0281 and wR2 = 0.0473). The crystal structure of both compounds is based on Mo16O26O10 units containing Mo16 clusters that share some of their O atoms to form infinite Mo-O cluster chains developing in the [010] direction and between which the Mg2+ or Li+ and Pr3+ cations are located. The increase of the charge transfer towards the Mo16 cluster due to the supplementary electron brought by the Mg2+ cations leads to some variations of the Mo-Mo distances. Application of the Mo-O bond-length–bond-strength relationship developed by Brown & Wu leads to a value of 55.1 electrons per Mo16 cluster in good agreement with that calculated from the stoichiometry (55 e-/Mo16). Magnetic susceptibility measurements confirm the presence of one unpaired electron on the Mo16 cluster.
