Synthesis, Crystal Structure, and Optical Properties of a Polyoxometalate-Based Inorganic−Organic Hybrid Solid, (n-Bu4N)2[Mo6O17(≡NAr)2] (Ar = o-CH3OC6H4)

A novel organic−inorganic hybrid solid, ( n -Bu 4 N) 2 [Mo 6 O 17 (NAr) 2 ] (Ar = o -CH 3 OC 6 H 4 ) 1, has been prepared by refluxing of ( n -Bu 4 N) 2 [Mo 6 O 19 ] and appropriate o -anisidine in acetonitrile with N - N ‘ -dicyclohexylcarbodiimide (DCC) as the dehydrating agent. Compound 1 has been characterized by single-crystal X-ray diffraction. Both of the two terminal o -anisidido ligands are linked, respectively, to an Mo atom of the hexamolybdate in a terminal fashion and exhibit an almost linear coordination mode of the Mo⋮N triple bond character. The two o -anisidido aryl rings on the hexamolybdate cluster lie in the cis position, allowing π−π stacking of phenyl ring among the anions. In the crystal, the cluster anions of 1 aggregate into an interesting 1D double chain along the a -axis through π−π stacking and C−H···O hydrogen-bonding interactions. Compared to the hexamolybdate parent, this solid has a smaller optical band gap of 2.25 eV from UV−visible-near-IR reflectance spectroscopy studies. It has also been characterized by 1 H NMR, IR, and UV/Vis spectroscopic techniques.