FLUXIONALITY AND PHOSPHANE ARM-OFF REACTIONS OF OCTAHEDRAL RUTHENIUM(II) COMPLEXES WITH THE TRIPODAL POLYPHOSPHANE MEC(CH2PPH2)(3)

Structural fluxionality is apparent in the H-1- and P-31-NMR spectra o f compounds of the type [Ru(L)(MeCN)(triphos)](CF3SO3), 2-5, at 25 deg rees C, where L represents a diorganyldithiocarbamate or a heterocycli c kappa(2)N,S coordinating thioamide. In contrast, complexes [Ru (Et2N CS2) (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 octahedra l coordination spheres of 2-5. Reaction of [Ru(MeCN)(3)(triphos)](CF3S O3)(2), 1, with Na(Et2NCS2) at a 1:2 molar ratio yields [Ru(Et2NCS2-ka ppa(2)S) (Et2NCS2-kappa S) (triphos]], 9,which slowly converts to [Ru( Et2NCS2-kappa(2)S)(2)(triphosO-kappa(2)P)], 10, on recrystallization f rom ethanol/acetone under air [triphosO is O=P(Ph)(2)CH2C(CH3) (CH2PPh 2)(2)]. A similer kappa(3)P-->kappa(2)P arm-off dissociation leads to the formation of [Ru(mpy-kappa(2)N,S)(2)(triphosO-kappa(2)P)] (13) and [Ru(mmim kappa(2)N,S)(2)(triphosO-kappa(2)P)] (14) (Hmpy = 2-mercapto pyridine, Hmmim = 2-mercapto-1-methylimidazole). Crystal structures ar e reported for [Ru(mbt-kappa(2)N,S) (MeCN) (triphos-kappa(3)P)](CF3SO3 ) (4) (Hmbt = 2-mercaptobenzothiazole), [Ru(mpym-kappa(2)N,S) (m-pym-k appa(2)N-S) (triphos-kappa(3)P)] (11) (Hmpym = 2-mercaptopyrimidine) a nd 14, the latter of which is present as the OC-6-13 isomer.