HINDERED ROTATION ABOUT SINGLE BONDS IN RUHX(CO)(P(T)BU(2)ME)(2) AND IRHCL2(P(T)BU(2)ME)(2)

摘要

Ru[C(O)Me]I(CO)L(2) (L=P'Bu(2)Me) shows H-1 and P-31 NMR evidence for existence of two conformers (distinguished by their rotational conformation about the Ru-P bonds) which show (at -80 degrees C) (a) no symmetry and (b) mirror symmetry (defined by the Ru[C(O)Me]I(CO) plane). The same is true of RuH(Cl)(CO)L(2). Ru(Me)I(CO)L(2) shows (H-1 and P-31 evidence) two conformers, each mirror symmetric, with a lower interconversion barrier than in the acetyl analog. The molecules RuCl(Ph)(CO)L(2) and RuH(Ph)(CO)(2)L(2) exhibit slow (H-1 and C-13 NMR time scales) rotation about the Ru-C(ipso) bond at 23 degrees C. Already at 23 degrees C, IrL(2)Cl(2)H shows H-1 and P-31 NMR evidence for two equally abundant (mirror symmetric) conformers due to hindered rotation about Ir-P bonds. [References: 24]