Aes. Miller et al., UNUSUAL KINETICS OF GAS-PHASE PROTON-TRANSFER TO MN(CO)(5)(-) AND RE(CO)(5)(-), International reviews in physical chemistry, 15(1), 1996, pp. 219-229
Rate constants for gas-phase proton transfer to Mn(CO)(5)(-), Re(CO)(5
)(-) and Cl- from reference acids and metal hydrides are determined. P
roton-transfer efficiencies to Mn(CO)(5)(-) are small, and less than t
he efficiencies for proton transfer to Cl-; proton-transfer efficienci
es to Re(CO)(5)(-) are larger than those for Mn(CO)(5)(-), but still g
enerally less than for transfer to Cl-. Proton-transfer efficiencies t
o Mn(CO)(5)(-) and Re(CO)(5)(-) are substantially more dependent on th
e nature of the proton donor (e.g. metal hydride versus oxy-acid). The
thermoneutral proton transfer between Mn(CO)(5)(-) and (CO)-C-13-labe
lled HMn(CO)(5) is particularly inefficient, occurring only in about 1
in 100 collisions. The results are discussed in view of evidence for
a short lifetime of the collision complex, and the effects of electron
ic and structural reorganization of Mn(CO)(5)(-) and Re(CO)(5)(-), inc
luding loss of fluxionality of the metal species, which occur on proto
nation.