The re
action of [(dip
pe)NiH]
2 with 2-methyl-3-butenenitrile (2M3BN) in solvents sp
anning
a wide r
ange of pol
arities shows signific
ant differences in the r
atio of C−H
and C−CN
activ
ated products. C−H cle
av
age is f
avored in pol
ar solvents, where
as C−C cle
av
age is f
avored in nonpol
ar solvents. This v
ari
ation is
attributed to the differenti
al solv
ation of the tr
ansition st
ates, which w
as further supported through the use of steric
ally bulky solvents
and we
akly coordin
ating solvents. V
ari
ation of the tem
per
ature of re
action of [(dip
pe)NiH]
2 with 2M3BN in dec
ane
and
N,
N-dimethylform
amide (DMF)
allowed for the c
alcul
ation of Eyring
activ
ation p
ar
ameters for the C−CN
activ
ation
and C−H
activ
ation mech
anisms. The
activ
ation p
ar
ameters for the C−H
activ
ation p
athw
ay were Δ
H
acs.org/images/entities/thermod.gif"> = 11.4
![](http://pubs.<font color=)
acs.org/im
ages/entities/plusmn.gif"> 5.3 kc
al/mol
and Δ
S
acs.org/images/entities/thermod.gif"> = −45
![](http://pubs.<font color=)
acs.org/im
ages/entities/plusmn.gif"> 15 e.u., comp
ared with Δ
H
acs.org/images/entities/thermod.gif"> = 17.3
![](http://pubs.<font color=)
acs.org/im
ages/entities/plusmn.gif"> 2.6 kc
al/mol
and Δ
S
acs.org/images/entities/thermod.gif"> = −29
![](http://pubs.<font color=)
acs.org/im
ages/entities/plusmn.gif"> 7 e.u. for the C−CN
activ
ation p
athw
ay. These p
ar
ameters indic
ate th
at C−H
activ
ation is f
avored enth
alpic
ally, but not entropic
ally, over C−C
activ
ation, implying
a more ordered tr
ansition st
ate for the former.