6 ), 6.90 (s, 6 ), and 8.35 (s, 15 H)). No significant line broadening was observed up to 167°t hough there appeared to be a slight high-field shift of the central carbomethoxy resonance again at this temperature. A rearrangement with k < 3 sec-1 could have been detected. The for the iridium complex is therefore at least 25 kcal mol-1, and this rearrangement occurs much less readily here.12 It is intriguing to speculate that a process involving formation of an intermediate corresponding to 1 (R/ = Me) but with Cl and -bonded hexamethyl(Dewar benzene) (HMDB) in place of C5Me5, may be involved in the [(HMDB)RhCl]2-catalyzed isomerization of HMDB to hexamethylbenzene recently reported by Volger and Hogeveen.15 Rh. This appears to be a general phenomenon for 4d and 5d metals; Cotton, et al., have shown that fluxional behavior is slower, and AH higher, for C8HiMe4W(CO)3 than for CsHi-MeaMo(CO)3,ls and Bruce, et at., have observed the same for CsHaOs-(CO)j and C8H8Ru(CO)3.'4 (13) F. A.

No abstract

No abstract

No abstract

No abstract