Binuclear, tetranuclear and hexadecanuclear thio-oxomolybdenum(V/IV) glycolates with selective adsorptions of gases.

By adjusting the pH values of the solutions, binuclear, tetranuclear and hexadecanuclear glycolato thio- and oxomolybdenum(V/IV) complexes [MoV2O 2 (μ 2 -O)(μ 2 -S)(Hglyc) 2 (Hpz) 2 ]·H 2 O (1, H 2 glyc = glycolic acid, Hpz = pyrazole), (Hdpa)[MoV2O 2 (μ 2 -S) 2 (Hglyc)(glyc)(H 2 O)] (2, dpa = 2,2'-dipyridylamine), (Hdpa) 4 [MoV4O 4 (μ 3 -O) 2 (μ 2 -S) 2 (glyc) 2 (S 2 O 3 ) 2 ] (3) and Na 2 [MoIV4MoV12O 12 (μ 2 -O) 6 (μ 2 -OH) 2 (μ 3 -O) 12 (glyc) 4 (Hpz) 4 (pz) 8 ]·28H 2 O (4) have been obtained successfully. Here the glycolates existed in varying aggregates with different degrees of protonation and deprotonation in 1-4. The stable formations of 1 and 2 are attributed to strong hydrogen bonds formed between the molecules. In particular, the asymmetric unit in 2 is a tetramer linked by hydrogen bonding [2.574(9) Å] between α-hydroxy and α-alkoxy groups for further construction of unsaturated penta-coordination environments. Moreover, deprotonated glycolates act as bridging ligands to form tetra- and hexadecanuclear compounds 3 and 4, respectively. The smallest unit in 4 exhibits mixed valences of 4+ and 5+ simultaneously, where its gas adsorption experiments manifest that 4 is obviously beneficial for O 2 and CO 2 compared with no adsorption of N 2 , CH 4 and H 2 at different pressures.