Fluxionality and Phosphane Arm-off Reactions of Octahedral Ruthenium(II) Complexes with the Tripodal Polyphosphane MeC(CH_2PPh_2)_3

摘要

Structural fluxionality is apparent in the ~1H- and ~(31)P-NMR spectra of compounds of the type [Ru(L)(MeCN)(triphos)](CF_3SO_3), 2-5, at 25 ℃, where L represents a diorganyldithiocarbamate or a heterocyclic κ~2N, S coordinating thioamide. In contrast, complexes [Ru(Et_2NCS_2)(Y)(triphos)]~(n+) (6, n = 1, Y = CO; 7, n = 0, Y = CN~-; 8, n = 0, Y = H~-) are stereochemically rigid in solution at this temperature, indicating that MeCN dissociation must occur for the crowded octahedral coordination spheres of 2-5. Reaction of [Ru(MeCN)_3(triphos)](CF_3SO_3)_2, 1, with Na(Et_2NCS_2) at a 1:2 molar ratio yields [Ru(Et_2 NCS_2-κ~2S)(Et_2NCS_2κS)(triphos)], 9, which slowly converts to [Ru(Et_2NCS_2-κ~2S)_2(triphosO-κ~2P)], 10, on recrystallization from ethanol/acetone under air [triphosO is O=P(Ph)_2CH_2C(CH_3)(CH_3PPh_2)_2]. A similar κ~3P→κ~2P arm-off dissociation leads to the formation of [Ru(mpy-κ~2N, S)_2(triphosO-κ~2P)] (13) and [Ru(mmim-κ~2N, S)_2(triphosO-κ~2P)] (14) (Hmpy = 2-mercaptopyridine, Hmmim = 2-mercapto-1-methylimidazole). Crystal structures are reported for [Ru(mbt-κ~2N, S)(MeCN)(triphos-κ~3P)](CF_3SO_3) (4) (Hmbt = 2-mercaptobenzothiazole), [Ru(mpym-κ~2N, S)(mpym-κS)(triphos-κ~3P)] (11) (Hmpym = 2-mercaptopyrimidine) and 14, the latter of which is present as the OC-6-13 isomer.