Synthesis and Crystal Structure of Cs 2 (CN 3 H 6 ) 3 [(C 2 H 5 ) 2 NH 2 ][W 7 O 22 (O 2 ) 2 ]·3H 2 O

A novel diperoxoheptatungstate was crystallised as a Cs + −CN 3 H 6 + −(C 2 H 5 ) 2 NH 2 + salt and characterised by a single‐crystal X‐ray diffraction method. The anion has a Lindqvist heptametallate structure. The metal atoms are located in a bent 2‐3‐2 arrangement with the central W 3 section (W3, W4 and W5) as the hinge. The peroxo groups coordinate the tungsten atoms at both ends of the W 3 section (W3 and W5). In the crystal polyanions, caesium and guanidinium cations, and water of crystallisation form tunnel‐like cavities, and the diethylammonium cations are accommodated in the cavities, suggesting a clathrate‐like feature for the compound. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)