Se and Related Chalcogen-Rich Trinuclear Clusters

MOLYBDENUM AND TUNGSTEN CLUSTERS AS AQUA IONS [M3Q4(H20)9] + (M = Mo,W Q = S,Se) AND RELATED CHALCOGEN-RICH TRINUCLEAR CLUSTERS 

Submitted by VLADIMIR P. FEDIN and A. GEOFFREY SYKES Checked by DIRK KUPPERT, KASPAR HEGETSCHWEILER, STEPHAN APPEL-COLBUS/ and HORST PHILIPP BECK  

The trinuclear incomplete cuboidal cluster [Mo3S4(H20)9] , first prepared in the mid-1980 s, combines a high degree of stability with quite unusual reactivity. One route for the preparation of [Mo3S4(H20)9] from Na2[Mo202S2 (cys)2] -4H20 is now well established, with yields typically 25%. In 1992 

Department of Chemistry, The University of Newcastle, Newcastle upon Tyne, NEl 7RU, UK. Universitat des Saarlandes, Anorganische Chemie, Postfach 15 11 50 D-66041 Saarbrucken. 

Molybdenum and tungsten powders with average particle size 10-20/pm (99.99%) have been used in these procedures. Such powders are generally free of oxide forms, but if old samples are used, they should be heated in a stream of H2 (1000°C, 1 h) prior to use. Commercially available 99.5% liquid bromine is recommended to avoid the need to remove H2O. Commercial 20% ammonium polysulfide (NH4)2Sy can be used, or alternatively solutions can be prepared by passing H2S through a suspension of sulfur (15 g) in 25% aqueous NH3 (110 mL) until complete dissolution of the sulfur occurs. White crystalline 98.5% 

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