The synthesis of the cluster dianion [Os10C(CO)24]2? by pyrolysis. X-Ray structure analysis of [N(PPh3)2]2[Os10C(CO)24] and [Os5C(CO)14H(NC5H4)]

Abstract

The Synthesis of the Cluster Dianion [Os, oC(CO)24]2-by Pyrolysis. X-Ray Structure Analysis of [ N(PPh3)2]2[O~10C(C0)24] t and [ oS&(co)~ 4H( N C d b ) ] *

Microwave-assisted synthesis of dimolybdenum tetracarboxylates and a decanuclear osmium cluster

“…Thick-walled 35-mL reaction vessels with Teflon-lined caps were provided by CEM. Caution must be exercised due to the toxic nature of CO and Mo(CO) 6 . All manipulations must be carried out in a highly efficient fume hood.…”

“…Our initial target was the decanuclear osmium cluster [N(PPh 3 ) 2 ] 2 [Os 10 C(CO) 24 ]. The standard method for its synthesis involves pyrolysis for 64 h [6]. We have found that microwave irradiation can be used to make this cluster in just over 1 h.…”

“…This often takes many hours and results in a low yield even when measures are taken to eliminate all traces of oxygen. For example, the standard procedure for the preparation of Mo 2 (O 2 CCH 3 ) 4 involves refluxing acetic acid, acetic anhydride and Mo(CO) 6 under N 2 gas for 20 h to obtain a 37% yield [3]. The method is improved with the use of selected solvents with higher boiling points.…”

“…A significant hazard associated with this reaction is the ease with which Mo(CO) 6 sublimes from the reaction mixture and deposits in the reflux condenser. The reaction setup has been known to explode as the condenser becomes completely blocked with small white crystals of Mo(CO) 6 .…”

“…In such chiroptical studies, Mo 2 (O 2 CCH 3 ) 4 is mixed with the chiral molecule in DMSO and the circular dichroism spectrum of the resulting solution is recorded and analyzed. Dimolybdenum tetracarboxylates are typically synthesized by refluxing the carboxylic acid (along with its anhydride when available) with hexacarbonylmolybdenum(0), Mo(CO) 6 , under an inert atmosphere [1]. This often takes many hours and results in a low yield even when measures are taken to eliminate all traces of oxygen.…”