The gas-phase reactivity of lanthanide (Ln+ =
La+−Lu+), group 2 (Ca+,
Sr+, and Ba+),
and group 3 (Sc+ and Y+) cations, and of
their corresponding monoxide ions MO+, with
pentamethylcyclopentadiene (C5Me5H) was
studied by Fourier transform ion cyclotron
resonance mass spectrometry. The reactivity of Eu+,
Tm+, Yb+, and the alkaline earth
metal
ions was similar to that observed previously for Sm+,
namely formation of the fulvenide ion
M(C5Me4CH2)+
as the main primary product and the metallocene ion
M(C5Me5)2
+ as
the
main secondary product. With Sc+, Y+,
and the remaining lanthanide series ions, several
other species were observed in the primary reactions, corresponding to
single and multiple
losses of neutral molecules such as H2 and CH4.
These differences in reactivity appear to
correlate with the accessibility of reactive excited state electron
configurations of the metal
ions. In the case of the metal oxide cations MO+,
the reactivity with pentamethylcyclopentadiene appears to be determined by the strength of the
M+−O bonds. The ions with the
strongest bonds, LaO+, CeO+,
PrO+, and NdO+, formed
M(C5Me5)(OH)+ as the
sole primary
product, which reacted further, eliminating water, to give the
metallocene ion
M(C5Me5)2
+.
ScO+, YO+, and the lanthanide series
ions SmO+, GdO+−TmO+, and
LuO+ yielded MO(C5Me4CH2)+ and
M(C5Me4CH2)+
as the primary products in addition to
M(C5Me5)(OH)+.
These
metal oxides gave
M(C5Me4CH2)2
+
and M(C5Me5)2
+
as secondary products. The ions with
the weakest M+−O bonds, EuO+,
YbO+, CaO+, SrO+, and
BaO+, formed MOH+ as a primary
product and M(C5Me5)+ as a
secondary product.
