The reacti
on
of 2 equiv
of the
bulky ligand
N,N'-
bis(3,5-di-
tert-
butylphenyl)-1,2-phenylenediamine, H
2[
3L
PDI], excesstriethylamine, and 1 equiv
of M(CH
3CO
2)
2·4H
2O (M = Ni, C
o) in the presence
of air in CH
3CN/CH
2Cl
2 s
oluti
onyields vi
olet-
black crystals
of [Ni
II(
3L
ISQ)
2] CH
3CN (
1)
or vi
olet crystals
of [C
o(
3L)
2] (
3). By using Pd(CH
3CO
2)
2 asstarting material, green-
blue crystals
of [Pd
II(
3L
ISQ)
2]·CH
3CN (
2) were
obtained. Single-crystal X-ray crystall
ographyrevealed that
1 and
3 c
ontain (pseud
o)tetrahedral neutral m
olecules [M(
3L)
2] (M = Ni, C
o) whereas in
2 nearlysquare planar, neutral m
olecules [Pd
II(
3L
ISQ)
2] are present. Temperature-dependent suscepti
bility measurementsesta
blished that
1 and
2 are diamagnetic (
S = 0) whereas
3 is paramagnetic with an
S =
3/
2 gr
ound state. It issh
own that
1 c
ontains tw
o ![](/images/gifchars/pi.gif)
radical
benz
osemiquin
onate(1-)-type m
on
oani
ons, ((
3L
ISQ)
1-
bull.gif">,
Srad =
1/
2), and acentral Ni(II) i
on (d
8;
S = 1) which are antiferr
omagnetically c
oupled yielding the
observed
St = 0 gr
ound state.This result has
been c
onfirmed
by
br
oken symmetry DFT calculati
ons
of
1. In c
ontrast, the
St =
3/
2 gr
ound state
of
3 is m
ore difficult t
o understand: the tw
o res
onance structures [C
oIII(
3L
ISQ)(
3L
PDI)]
![](/images/entities/harr.gif)
[C
oII(
3L
PDI)(
3L
IBQ)] might
beinv
oked (f
or tetrahedral [C
oII(
3L
ISQ)
2] c
ontaining an
SCo =
3/
2 with tw
o antiferr
omagnetically c
oupled
![](/images/gifchars/pi.gif)
-radical ligandsan
St =
1/
2 is anticipated). C
omplex
2 is diamagnetic (
S = 0) c
ontaining a Pd
II i
on (d
8,
SPd = 0 in an alm
ostsquare planar ligand field) and tw
o antiferr
omagnetically c
oupled ligand radicals (
Srad =
1/
2). The electr
ochemistryand spectr
oelectr
ochemistry
of
1, 2, and
3 have
been studied, and electr
on-transfer series c
omprising the species[M(L)
2]
z (
z = 2+, 1+, 0, 1-, 2-) have
been esta
blished. All
oxidati
ons and reducti
ons are ligand centered.