SYNTHESES, STRUCTURES AND REACTIVITY OF ETA(6)-ARENE-ETA(5)-2,3-DIHYDRO-DIBOROLYL-RHODIUM COMPLEXES

The reactions between dirhodium-mu-dichloro-tetraethylene and the 2,3- dihydro-1,3-diborole derivatives 1a,b in toluene and benzene yield the sandwich complexes 3a-c and 4a,b. Their compositions have been derive d from spectroscopic and analytical data and were confirmed by single crystal structure analyses for 3a, b, c and for 4b. On heating, these compounds lose the arene ligand and the remaining complex fragments un dergo stacking with formation of triple-decker complexes (6a,b) and a tetradecker complex (7b). Thermogravimetric analyses of 3 and 4 indica te that the decomposition occurs in two steps: the first represents th e elimination of the arene and the second the thermal decomposition of the residue. (C) 1998 Elsevier Science S.A. All rights reserved.