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(μ-O)(μ-S)(Hglyc)(Hpz)]·HO (1, Hglyc = glycolic acid, Hpz = pyrazole), (Hdpa)[MoV2O(μ-S)(Hglyc)(glyc)(HO)] (2, dpa = 2,2'-dipyridylamine), (Hdpa)[MoV4O(μ-O)(μ-S)(glyc)(SO)] (3) and Na[MoIV4MoV12O(μ-O)(μ-OH)(μ-O)(glyc)(Hpz)(pz)]·28HO (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 and CO compared with no adsorption of N, CH and H at different pressures.