*Article* **First Organic–Inorganic Hybrid Compounds Formed by Ge-V-O Clusters and Transition Metal Complexes of Aromatic Organic Ligands**

**Hai-Yang Guo 1,2, Hui Qi 3, Xiao Zhang <sup>4</sup> and Xiao-Bing Cui 1,\***


**Abstract:** Three compounds based on Ge-V-O clusters were hydrothermally synthesized and characterized by IR, UV-Vis, XRD, ESR, elemental analysis and X-ray crystal structural analysis. Both [Cd(phen)(en)]2[Cd2(phen)2V12O40Ge8(OH)8(H2O)]·12.5H2O (**1**) and [Cd(DETA)]2[Cd(DETA)2]0.5 [Cd2(phen)2V12O41Ge8(OH)7(0.5H2O)]·7.5H2O (**2**) (1,10-phen = 1,10-phenanthroline, en = ethylenediamine, DETA = diethylenetriamine) are the first Ge-V-O cluster compounds containing aromatic organic ligands. Compound **1** is the first dimer of Ge-V-O clusters, which is linked by a double bridge of two [Cd(phen)(en)]2+. Compound **2** exhibits an unprecedented 1-D chain structure formed by Ge-V-O clusters and [Cd2(DETA)2] 4+ transition metal complexes (TMCs). [Cd(en)3]{[Cd(η2-en)2]3[Cd(η2-en)(η2-μ2-en)(η2-en)Cd][Ge6V15O48(H2O)]}·5.5H2O (**3**) is a novel 3- D structure which is constructed from [Ge6V15O48(H2O)]<sup>12</sup><sup>−</sup> and four different types of TMCs. We also synthesized [Zn2(enMe)3][Zn(enMe)]2[Zn(enMe)2(H2O)]2[Ge6V15O48(H2O)]·3H2O (**4**) and [Cd(en)2]2{H8[Cd(en)]2Ge8V12O48(H2O)}·6H2O (**5**) (enMe = 1,2-propanediamine), which have been reported previously. In addition, the catalytic properties of these five compounds for styrene epoxidation have been assessed.

**Keywords:** polyoxometalates; vanadogermanate; secondary transition metal substituted Ge-V-O clusters
