other hand, since the central atom g and f orbitals presumably hardly have any importance for the chemical bonding, the energy difference observed between ...
Interpretation of Electron Transfer Spectra of Iridium (IV) and Osmium(IV) Mixed Chloro-Bromo Complexes C H R . K L I X B Ü L L JØRGENSEN
Cyanamid European Research Institute, 1223 Cologny (Geneva), Switzerland and W .
PREETZ
Institut für Analytische Chemie und Radiochemie der Universität des Saarlandes, 66 Saarbrücken 15 (Z. Naturforschg. 22 a, 945—954 [1967] ; received 27 February 1967)
The previous M.O. treatment of unsubstituted hexahalides has been modified, taking the results on FARADAY effect obtained at the University of Virginia into account. The absorption spectra previously measured of the complexes (M = Os, Ir) £r16
electronegativity
optical
T h i s set is the o n l y o n e having the same s y m m e t r y
rropt. This argument cannot be
type (Y4U in BETHE, t l u in MULLIKEN'S n o m e n c l a t u r e )
corresponding
lower
extended to R e ( I V ) 7 . W e are n o w discussing
the
e n e r g y levels expected f o r substituted c h r o m o p h o r e s of o r t h o a x i a l type
MAXBG_X
17
i. e. all six ligands A
and B can b e situated o n the axes of a Cartesian
as o n e of the sets of o-orbitals. T h e effect o n the intensities of
transitions to the h i g h e r
are s p e c t a c u l a r 1 3 ;
d-sub-shell
it is nearly certain that the ad-
mixture of o-character to the rr-set [ w h i c h w e h e n c e
c o o r d i n a t e system, and w e start b y c o n s i d e r i n g the
call (JI + o ) y 4 u ] is responsible f o r nearly all o f the
unsubstituted h e x a h a l i d e M A 6 .
electric d i p o l e oscillator strength o b s e r v e d . T h u s , it m a y b e argued that o n e should assign " Z " = 3 rather
Unsubstituted Hexahalides Until recently, it was assumed
than 1 to the ^ - c o m b i n a t i o n which has to b e o r t h o -
MA6
gonal
10'13,14
that the
o r d e r of the twelve CT orbitals f o r m e d b y the loosest of
angular
node-planes18
which
25
on the o - c o m b i n a t i o n " p " and h e n c e devel-
a node-cone,
the M . 0 .
wavefunction
having
o p p o s i t e sign f o r f o u r ligands relative to the two
by
others o n one Cartesian axis. It is generally r e c o g -
also
nized that a n o d e - c o n e counts f o r two n o d e - p l a n e s .
b o u n d , filled p shell of A w a s that determined the n u m b e r
ops
indicates the lowest value of I f o r central a t o m o r bitals which are able to m i x with the c o m b i n a t i o n of l i g a n d orbitals. W e call this q u a n t u m n u m b e r " Z " and write " s " , " p " , " d " , " f " , " g " . . . f o r " Z " = 0 , 1, 2 , 3 , 4 , . . . Said in other w o r d s , the f o u r sets of ."r-orbitals have " Z " = 4 , 3, 2 , 1 and the three sets of o-orbitals " Z " = 2 , 1, 0. H o w e v e r , in octahedral symmetry, the n u m b e r of degenerate orbitals is not alw a y s ( 2 1 + 1) like in spherical s y m m e t r y
but it is
10
3 , 3 , 3 , 3 , 2 , 3 , 1 in the sets m e n t i o n e d . T h e e n e r g y d i f f e r e n c e between the rr-orbitals " f " and " d "
can
b e ascribed to the central a t o m d orbitals f o r m i n g a b o n d i n g M . 0 . b y c o m b i n a t i o n with the latter set (as experimentally verified b y the study of h y p e r f i n e structure of the p a r a m a g n e t i c r e s o n a n c e curve
in-
M
d u c e d b y the i r i d i u m and chlorine n u c l e i 1 9 ) . O n the
(
„
other hand, since the central a t o m g and f orbitals presumably chemical
hardly
bonding,
have
any
the energy
importance
for
difference
the
observed
between the " g " and " f " cr-orbitals must b e caused '
b y MCCLURE'S effect, i. e. the increased kinetic energy
20, 21
d u e to the f o u r rather than three angular
node-planes.
Similar
arguments
can
be
extracted
f r o m SCHMIDTKE'S article o n t o p o l o g i c a l matrices
22.
In tetrahedral c h r o m o p h o r e s M X 4 , the loosest b o u n d c o m b i n a t i o n of ^ - o r b i t a l s is " f " h a v i n g the highest n u m b e r of angular node-planes
16' 23' 2 4 .
These arguments have always been slightly
un-
certain in the case of the yr-orbitals having " Z " = l . 16
C. K. JORGENSEN, Halogen Chem. 1, 265 [1967].
17
C . E . SCHÄFFER a n d C . K . JORGENSEN,
18
D . S . MCCLURE, S o l i d S t a t e P h y s . 9 , 3 9 9
19
J . H . E . GRIFFITHS a n d J . OWEN, P r o c . R o y . S o c . L o n d o n
Kgl. Danske
skab. Selskab Mat. Eys. Medd. 34, no. 13 [1965].
226,96 20
22
A
C. K. JORGENSEN, Chem. Phys. Letters 1, 11 [1967]. 1I.-H. SCHMIDTKE, J. Chem. Phys. 45, 3920 [1966].
23
A . CARRINGTON
24
[1961]. P. DAY and C. K. JORGENSEN, J. Chem. Soc. 6226 [1964]. C. K. JORGENSEN, J. Phys. Radium 26, 825 [1965].
[1959]. 25
[1954].
8u
Fig. 1. The energy differences between 8 of the 12 energy levels formed from six halide ligands as a function of their LANDE parameter. In the non-relativistic case at the left-hand side, the energy difference between JT4g and (?r + o)4u has been taken as the average for a variety of hexahalide complexes. In our case of Os(IV) and Ir(IV), it is hardly larger [Eq. (9)] than between (.t+o)4 U and jrsu . However, since the even and odd levels do not mix, this only shifts the two highest curves. The dashed curves correspond to relativistic orbitals from which transitions to a central atom orbital have no oscillator strength. 21
Viden-
0
and
K. RUEDENBERG, Rev. Mod. Phys. 34, 326 [1962].
Unauthenticated Download Date | 11/24/15 4:07 AM
C . K . JORGENSEN,
Mol.
Phys.
4,
395
Said in other w o r d s , whereas the lowest " p " o-orbital
the
has o n l y one n o d e - p l a n e like the angular
effect28'
function
clearest 29.
argument
comes
the 7r-orbitals of same symmetry type have
MCCAFFERY and SCHATZ 1 6 '
o n e n o d e - p l a n e and o n e n o d e - c o n e similar to the
the transition f r o m " ~ f "
angular
20.5 kK
(z/r),
f function
z(5z2-3r)/r3.
The
question
from
the
FARADAY
A c c o r d i n g to a kind c o m m u n i c a t i o n f r o m there is n o d o u b t that
30
o c c u r s at l o w e r
(1 kK = 1 0 0 0 c m - 1 )
energy,
in I r C l 6 " than f r o m
whether this " ~ f " set of symmetry type /4 U o r the
"f"
" f " set of symmetry type 7gu [having
c h r o i s m i n d u c e d b y the external magnetic field has
c o m p a r a b l e to z(x2
node-planes
has highest e n e r g y be-
— y2)/r3]
F i g u r e 1 s h o w s the influence of
o f the central atom empty p orbitals f o r m i n g b o n d with
" ~ f"
are m o r e 1 3
or
di-
o p p o s i t e , a n d k n o w n , signs in the two cases.
c o m e s a question of whether the stabilizing influence ing combinations
at 2 3 . 0 and 2 4 . 4 k K because the circular
the
relativistic
( s p i n - o r b i t c o u p l i n g ) e f f e c t s 1 0 ' 1 3 in the halide ligands
less
represented b y i n c r e a s i n g values of the LANDE pa-
i m p o r t a n t than the ligand-ligand anti-bonding effect
rameter tnp f o r the h a l o g e n
b e c a u s e of the n o d e - c o n e between cr- and o contribu-
orbital e n e r g y differences are essentially taken f r o m
tions to
"~f".
Actually, gand-ligand
the
evidence is
accumulating26'27
anti-bonding
effects can
be
P
[n + o) 7 4 u ( t i u ) « £5 5
"
"d"
71
"d"
Ö
"s"
Ö
=
f
Y~>g (l-2g)
"
i A
T
R
^ —
Tl
n
TJ
n
jj IT
large
n
IJ
n
IT n P—tlx
r/2
«,ang |
IT
par
Hd _ Hn
TT
AI
TT2 n JIP
_
"JTPAR
ti.-i—na
n
II2 11
2 n A trans
IT 2
n
n &
i / 7
A eis
j
an
IT — nJ, T tlx a
2 Ha c ; s
E — Ha
7TG(AIG)
an
TT
TJ
f
a
a n g
r/2
n
H„ + Hn
^ —
73G(EG)
( o + j r ) y 4 u(tlu)
"P"
+
It —
E
^ 75U (t 2 l l )
for
justification w o u l d b e :
E — Hn
* 74g (tig)
concording
DAY effect just discussed. H o w e v e r , their qualitative
great
i m p o r t a n c e f o r the loosest b o u n d M . 0 . In o u r case,
"g"
spectra13
T h e non-relativistic
n u m b e r of h e x a h a l i d e c o m p l e x e s and f r o m the FARA-
that liof
absorption
16.
1
TT
2 n
ad
^
JJ^
o trans
n
(1)
Til
OP
U tt p —IIt l
a
HI,. JJ JJ
2 H0 trans
In these equations, H„ and H0 represent the d i a g o n a l
ligand-ligand
elements
element f o r a given s y m m e t r y type y^ as is also the
of
energy characterizing
non-bonding
n-
bonding
effects change the
diagonal
a n d a-orbitals. Their difference is partly a l i g a n d
case f o r the d i f f e r e n c e between H T and
field effect influencing the potential, the a-orbitals
alternative
b e i n g m o r e stabilized b y the positive central a t o m
a t o m i c orbitals as starting material w o u l d
consider
than the jr-orbitals. Other reasons m a y b e the ortho-
the l i g a n d - l i g a n d
elements
gonalization
between degenerate orbitals. Hn
phore.
c o n d i t i o n s in general in the
The
first-order
(proportional expressions
perturbation
to other H ) ,
and
chromo-
expressions
the
( H 2 d i v i d e d b y Hl — H2)
treatment31
of
effects as n o n - d i a g o n a l
The
ang
indicates the non-
d i a g o n a l element a p p r o p r i a t e f o r t w o crc-orbitals of
second-order
a d j a c e n t l i g a n d atoms in e x p o s i t i o n , h a v i n g ortho-
derive
g o n a l n o d e - p l a n e s . It is expected that this n o n - d i a g -
from
interactions between orbitals having identical ener-
onal
gies o r h i g h l y different energies. In the WOLFSBERG—
parallel jr-orbitals
HELMHOLZ m o d e l 1 0 ' 1 1
h a v i n g the same n o d e - p l a n e . W e neglect
and
Ha.
non-symmetry-adapted
related treatments,
the
26
C . K . JORGENSEN, C o o r d . C h e m . R e v . 1 , 1 6 4
27
R . PAPPALARDO a n d C . K . JORGENSEN, J . C h e m . P h y s . 4 6 , 6 3 2
[1966].
28
P. J. STEPHENS, Inorg. Chem. 4, 1690 [1965].
29
B . BRIAT, M . BILLARDON, J . BADOZ, a n d J . LORIERS,
30
[1967].
element
is larger on
A . J . MCCAFFERY a n d
than H„ two
par
ligands
involving in
P . N . SCHATZ, p e r s o n a l
two
czs-position non-diagcommunica-
tion. 31
C . E . SCHXFFER
and
C . K . JORGENSEN,
[1965]. Analyt.
Chim. Acta 34, 465 [1966].
Unauthenticated Download Date | 11/24/15 4:07 AM
M o l . Phys. 9, 401
onal elements between rr-orbitals in ligands in position. Hnvis
trans-
is the n o n - d i a g o n a l element between
the subtraction of the diagonal elements H ^ and H x in ( 2 )
and ( 3 ) represents approximately the effect
two o-orbitals o n ligands in a s - p o s i t i o n s and is ex-
of positive local kinetic energy
pected
values since we can write SCHRÖDINGER'S equation
to
WIRTH
be
much
larger
performed
32
than
//„trans
though
WOLFSBERG—HELMHOLZ
calcu-
lations f o r C O ( N H 3 ) 6 + 3 and f o u n d a n o n - n e g l i g i b l e
for
stationary
overlap integral between the t w o rather diffuse lonefirst-order
in
by
(1)
are f o u n d
ligand-ligand
summing
the
and
real
" d "
33' 34.
T h u s , SYMONS 3 5
f o r the energies of
the
three sets of o-orbitals.
influence of MADELUNG potentials on the elements of such m o d e l s 3 ' , the local
Equation ( 1 ) has not taken into a c c o u n t that antib o n d i n g M . 0 . are m o r e a n t i - b o n d i n g than the c o r r e -
ative in a certain r e g i o n rjj ~ 3 b o h r because of the m o r e positive U in
s p o n d i n g b o n d i n g M . 0 . are b o n d i n g . If the changes of kinetic energy in the b o n d r e g i o n are evaluated one would
to a certain a p p r o x i m a t i o n
expect
for
b o n d i n g situations, i . e . negative c o e f f i c i e n t s in (*-l)
H
2
21
(1),
and
It is clear " ~ f"
and
difference
that
"f"
(4). the energy
represented
between
the
difference
by
two
first
the
between
wavenumber
LAPORTE-allowed
a b s o r p t i o n b a n d s m a y vary rather much a c c o r d i n g to circumstances because of the c o m p e n s a t i n g
[/4
— //M — H\] S f r x
(2)
and f o r anti-bonding situations H2=
diagonal
is m o r e neg-
\
+ A
the c o r r e s p o n d i n g
5mx
square-roots
for
(3)
the
first-
con-
tributions to the energy of " ~ f " . Actually, there is g o o d evidence
16' 3 8 - 4 0
TiCl6
and WC1 6 have a smaller
, NbCl6-
that d ° - c o m p l e x e s such as energy
difference, p r o b a b l y c o r r e s p o n d i n g to smaller /(//T — H0)
H20:i
in the less compressed c o m p l e x e s . A t the
same time, the transition f r o m " ~ f " b e c o m e s rela-
o r d e r perturbations, x is a constant expected to be
tively less intense than f r o m " f " . Solvent effects
somewhat
and c o m p r e s s i o n
above
1;
the case
x = l
occurs
if
eigenfunctions are the original c o m b i n a t i o n xpx
the of
ligand orbitals and the c o m b i n a t i o n m a d e o r t h o g o n a l to it, i . e .
the normalized
form
are
to
in salts
increase
the
such as Cs 2 IrCl 6
difference
between
14
seem " ~ f"
and " f " .
of
where 5\ix is the overlap integral. T h e //>[ and
also
lo
On the other hand, the energy difference between quantities
the asymptotic values of the e x p o -
" g " and " f " represented by the w a v e n u m b e r difference between
the first LAPORTE-forbidden
and
the
nents f o r large r, xp = k exp ( — ju r), p r o d u c i n g a neg-
s e c o n d LAPORTE-allowed band stays remarkably c o n -
ative local contribution to the kinetic e n e r g y
stant and is {Hn
36
and
ang
— H-, p a r ) in the m o d e l ( 1 ) . T h e
T. H. WIRTH, Acta Chem. Scand. 19. 2261 [1965]. C. K. J0RGENSEN, Mol. Phys. 4, 231 [ 1 9 6 1 ] .
38
S. M. HORNER and S. Y. TYREE. Inorg. Nucl. Chem. Letters
34
C . K . JORGENSEN a n d J. S. BRINEN. M o l . P h y s . 5 , 5 3 5 [ 1 9 6 2 ] ,
39
B . J . BRISDON, T . E . LESTER, a n d
35
M . C . R . SYMONS, J. C h e m . S o c . 1 9 6 4 . 1 4 8 2 .
36
C. K. JORGENSEN, Proc. Bressanone Conference, July 1967.
37
C . K . JORGENSEN, S . M . HORNER, W . E . HATFIELD, a n d S . Y .
32 33
1, 43 [1965]. R . A . WALTON,
communication. 40
J. L. RYAN, personal communication.
TYREE, Int. J. Quantum Chem. 1, 191 [ 1 9 6 7 ] .
Unauthenticated Download Date | 11/24/15 4:07 AM
personal
observed values are 6 . 8 k K f o r T i C l 6 RUC1 6 ~ 3 ,
7.5 kK
for
WC16,
5.8 kK
, 6.8 kK for for
OsCl6~,
systems is i ^ g , i. e. the lower sub-shell has the pure configuration y$g4 y^g,
j,/-coupling
the transitions
6 . 2 kK f o r O s C l 6 - 3 and 6 . 8 kK f o r I r C l 6 ~ . This is
f r o m yc,u orbitals to this 77 g -hole are s y m m e t r y - f o r -
remarkably large quantity f o r effects of ligand-ligand
b i d d e n , and the even orbitals
anti-bonding.
tions are LAPORTE-forbidden) and y-H0)
in the
(1). call the
"Vir-
in IrCl 6
the
and 0 . 7 kK
in
) is mainly due to the energy difference beof ( 5 ) though it was expected
to be only 0 . 4 5 kK a c c o r d i n g to ( 6 ) . It is possible
£a3g
+
OsCl 6
(the difference between
is 1.4 kK
tween 2 y-u and 2
o3g
that 3 ygu and 2 y yi% of
tral a t o m a n d ligand JI- and o-orbitals in m a n y dif-
can b e r e c o g n i z e d as c o r r e s p o n d i n g to those
ferent c h r o m o p h o r e s . T h e type £ r a n s - M A 4 B 2 h a v i n g
results in b o t h OsBre
and
Ir(IV)
cases13.
The
individual
bands
of
the s y m m e t r y D 4 h can b e c o n s i d e r e d as the super-
[ 4 k K in the case of { n + o ) - > 5 d j'3 g ]. A c -
p o s i t i o n of quadratic M A 4 and linear M B 2 . W e use
tually, the agreement is better than c o n c e r n i n g the
BETHE'S n o m e n c l a t u r e f o r tetragonal s y m m e t r y , giv-
shift 12 — 13 k K between the isoelectronic
OsBr6-3
ing MULLIKEN'S n o m e n c l a t u r e in parenthesis, as de-
It is interesting to c o m p a r e F i g . 1 with OsI 6 ~ 3 and
parity is a d d e d as a further s p e c i f i c a t i o n if D 4 h and
o b t a i n e d b y a d d i n g 5 . 7 kK to the w a v e n u m b e r s IrBr6
and I r B r 6 OsI6
rived f r o m octahedral s y m m e t r y . T h e even or
.
having
transitions
41
three
LAPORTE-allowed
n — 5 d 75g
r o u g h l y equidistant with the difference
3 k K . This is qualitatively
in agreement with
the
positions expected f o r 3 /gu > 2 y 7 u and 2 ygu but o n l y if the effective value of £ is somewhat a b o v e the value 5 . 0 7 k K f o r the isolated i o d i n e atom ( 6 ) . T h e intermediate
coupling
has p r o g r e s s e d
t o w a r d the j,/-extreme 2 /7u and 2 t V pected
to
is not much b e l o w the —
be
f 04u f r o m some
strongly
that the difference between (5)
8 kK,
difference
which w o u l d b e ex-
since
the
1 7 8 u ~ ^ 5 d } ' 3 g has been identified OsI6
so
13
broad
°4u «
— WT5u ~ 3 k K and
and
7i ( a i ) = /'ti ( a i ) »
76 = n o ,
72(^2) = 7 t 3 ( b i ) ,
7i =
73(e)
78 = 7to + 7 t i -
=7ti(ai)+7t3(bi),
7a, (8)
74 (ti) = 7 t 2 ( a 2 ) + 7 t s ( e ) , 75 (ta) = 7 t 4 ( b 2 ) + y t 5 ( e ) , U s i n g the c o o r d i n a t e s g i v e n in T a b l e 4 of ref.
the
43
non-relativistic orbitals g i v e n in T a b l e 1 have welldefined s y m m e t r y
types ytk
and their e n e r g y
and
the first-order relativistic splitting c a n b e calculated.
at 4 4 . 6 k K f o r
It is sufficient to c o n s i d e r the d i a g o n a l sum rule and
) . T h e differ-
e n c e between 3 ygu and 1 y%n in the j,/-limit f C + tV ^4u - 4
Oh are c o n s i d e r e d rather than D 4 and O :
band
, i. e. 1 7 . 8 k K a b o v e 3 y s u - ^ 5 d y3g (the anal-
o g o u s distance is 1 9 . 5 kK f o r P t l 6
odd
suggests
(5) that
is 7i4u
— o 4 u ~ 12 k K appropriate f o r
the i n v a r i a n c e of s q u a r e d elements of the secular determinant [ E q . ( 9 3 ) of r e f . 4 3 ] in o r d e r to obtain these results. It has p r e v i o u s l y been s h o w n
13'16
that in c u b i c s y m m e t r y , the orbitals YQ consist (co=^)
components
of
of
the p-shell of the ligands
h e x a c h l o r o c o m p l e x e s cannot b e far off f o r h e x a i o d o
and yi e x c l u s i v e l y of (co = f ) , h a v i n g the c o n t r i b u -
complexes
tion
either. T h i s
discrepancy
cannot b e
re-
m o v e d within the f r a m e of o u r m o d e l , because the
+
In T a b l e 2 , the o b s e r v e d
and calculated
energy
two distances between a d j a c e n t b a n d s in the visible
levels of i r i d i u m ( I V )
are k n o w n to b e nearly identical.
c o m p a r e d , and in T a b l e 3 , a similar c o m p a r i s o n is
However, understood 41 42
we
should
everything.
not
believe that we
have
It is striking that each
C. K. J0RGENSEN, Acta Chem. Scand. 17, 1043 [1963]. J. C. EISENSTEIN, J. Chem. Phys. 25, 142 [1956].
of
chloro-bromo
complexes
are
m a d e f o r o s m i u m ( I V ) . T h e agreement is satisfactory in spite o f the f o l l o w i n g d i f f i c u l t i e s : 43
C. K. JORGENSEN, Absorption Spectra and Chemical Bonding
in Complexes, Pergamon Press, Oxford 1962.
Unauthenticated Download Date | 11/24/15 4:07 AM
Symmetry type cubic tetragonal r 1 7t5g 1i yt2g
( A 1 A A
r 1 7t5u
/ A { A A
1 7t2u -T 75U
oy4u
Wavefunction
r 1 yt5u 1i 7t4u Ir 1 7t5u 1[ 7t2u
A z4 — B 2/5+B ?/6 J -A
y2 — A
X3 + A
•AZ, + A Z
A Z
2
- A Z
3
+AZ
4
3
- A Z
4
+ H AN
+ }
J
(7teg >'t6g
6
/
-AO, •Bö,
First-order relativistic correction
ang
H \ „ + H \ A „
XX
-AX 4 + BX 5 + BZ 6
\A I A A f A 1 A B
Non-relativistic energy
HAO
«AB,par
— I CB
non-diagonal elements
't6u
° 0 0
PAR
+ IHAAO
#BO+£
b,teu
#BBO
trans trans
_
CA
CA
Table 1. Energies of the filled M.O. in */-ans-MA4B2. The results can be applied to MA 5 B removing the parity of the grouptheoretical quantum numbers and, when the ligand A replaces B on one of the positions 5 or 6, replacing £B by (£A+CB)/2 . Symmetry type cubic non-relativistic tetragonal non-relativistic tetragonal relativistic IrCl 6 — obs. 1 3 IrClsBr— obs. 8 ealc. Jran-s-IrCUB^ obs. 9 ealc. frans-IrCl2Br4 obs. 9 ealc. IrClBr 5 — obs. 8 ealc. IrBrß obs. 1 3 ealc. /fflC-IrCl3Br3— obs. 9 calc. cubic relativistic
(71+
71 74g
yteg
yt7g
7t6g
17.0
14.23 15.5 13.66 13.9
Hi. I —
15.1 12.05 11.8 12.4 11.6
—
14.5 —
12.9 11.6 11.4 13.17 14.2 ys g
—
17.0 —
17.0 —
14.7 —
13.9 13.4 13.2 15.43 15.1 76g
o)y\u
Ytbu
7t2g
ytsg
7t7u
7t6u
18.8 19.0 17.24 17.4 16.56 18.0 15.62 16.4 14.3, 14.9 14.9 17.68 17.7 7 8u
y t5u
7t2u
20.5 19.65 19.6 —
18.6 14.8 15.3 14.5 15.1
7t6u
—
20.5 —
20.5 20.08 18.2 —
17.4 —
16.7 —
18.6 76u
7t7u
7t4u 7t6u
7t7u
23.0, 24.4
22.05 22.2 21.64 20.6 18.08 18.5 17.68 18.2 17.15 17.5 20.5 20.6 7?u
23.6 23.7 — 23.53 21.8 23.7 21.14 22.27 21.2 21.4 18.95 20.6 20.2 20.1 18.35, 19.7 19.3 22.32 21.5 7 8u —
22.8
Table 2. Assignments of absorption bands of iridium (IV) complexes. Symmetry type cubic non-relativistic
^74g
tetragonal non-relativistic t e t r a g o n a l relativistic
OsCl 6 — obs. 1 3 OsCloBr—obs.s calc. 1 3
is
the
j,/-coupling
but also that the effects
of interelectronic repulsion between the partly
filled
the geometrical
isomers have
structures
of this g r o u p at least as different as two c o m p l e x e s of different c o m p o s i t i o n . It has been s h o w n that the c o n c e p t of h o l o h e d r i z e d symmetry
17' 2 5
can b e ap-
5d-shell and the l o w e r orbitals d o n o t separate in-
plied to electron transfer spectra with the same suc-
dividual terms of a given M . 0 . c o n f i g u r a t i o n to any
cess as to internal transitions in the partly
large extent. This is not trivial b e c a u s e the first ex-
d-shell in octahedral orthoaxial c o m p l e x e s .
filled
y-Radiolyse von flüssigem Kohlenoxid bei —196 °C H . W . BUSCHMANN
und
W .
GROTH
Institut für Physikalische Chemie der Universität Bonn (Z. Naturforschg. 22 a. 954—960 [1967] ; eingegangen am 12. Februar 1967)
The radiation chemistry of liquid carbon monoxide at —196 °C and mixtures of CO with various gases has been investigated. In the y-radiolysis of pure CO C0 2 is formed with G(C0 2 ) =0.18. The addition of CH4 , C 2 H 4 , 0 2 , and NO leads to the formation of C 3 0 2 which is not observed in the }'-radiolysis of pure CO. In the case of CO —CH4 mixtures the following reacting products were identified: CoH 6 . C.,H 2 , H X O , H 2 C 2 0 (Ketene), C0 2 and C 3 0 2 . Results of experiments with C O - C H 4 - 1 3 C H 4 "and CO — CH4 — CD4 mixtures and measurements of the dependence of G ( C 0 2 ) , G(C 3 0 2 ), G(C 2 H 2 ) and G(C 2 H 6 ) on the concentration of CH4 have shown that ethane is formed by energy transfer from CO to CH4 or by reaction of CH4 with excited CO and that C 3 0 2 and C 2 H 2 are formed by reaction of free carbon atoms which are formed in the presence of methane.
V o n photochemischen Untersuchungen her ist be-
B i l d u n g v o n m o n o m e r e m K o h l e n s u b o x i d ist bei der
kannt, daß sich K o h l e n o x i d bei Bestrahlung mit den
y - R a d i o l y s e des K o h l e n o x i d s auch nicht zu erwarten,
Linien
1 2 3 6 Ä und
2062 Ä
2
1295 Ä
1
s o w i e mit der
Linie
da M e s s u n g e n
in unserem
Laboratorium
ergeben
unter B i l d u n g v o n K o h l e n d i o x i d und K o h -
haben, d a ß K o h l e n s u b o x i d unter d e m Einfluß ioni-
l e n s u b o x i d zersetzt. D a g e g e n beobachtet m a n bei der
sierender Strahlung mit G{ — C 3 0 2 ) = 1 0 5 p o l y m e r i -
/-Radiolyse
des K o h l e n o x i d s 3 ' 4
von Kohlendioxid
z w a r die
mit G ( C 0 2 ) = 2 , 0 ,
Bildung
anstelle
von
siert. Bei der Bestrahlung v o n verflüssigtem reinem K o h l e n o x i d bei
— 196
C beobachtet man ebenfalls
K o h l e n s u b o x i d findet m a n j e d o c h ein festes b r a u n e s
die B i l d u n g v o n K o h l e n d i o x i d .
R e a k t i o n s p r o d u k t . Dieses ist im Gegensatz zu ther-
unter diesen B e d i n g u n g e n nicht nachweisbar.
misch o d e r strahlenchemisch p o l y m e r i s i e r t e m K o h l e n s u b o x i d in allen untersuchten Lösungsmitteln löslich. Es ist anzunehmen, daß es sich bei Reaktionsprodukt
um
eine
innige
nicht
diesem
Mischung
von
K o h l e n s u b o x i d und f r e i e m Kohlenstoff handelt. D i e
1
W . GROTH, W . PESARRA U. H . J . ROMMEL, Z . P h y s i k .
Chem.
Setzt m a n j e d o c h d e m verflüssigten
Kohlenoxid
Gases
Kohlensuboxid
gebildet.
Die
Radiolysepro-
dukte verschiedener Gasmischungen sind in T a b . 1 zusammengefaßt. 3
S . DONDES, P . HARTECK u . H . V. WEYSSENHOFF, Z . N a t u r f o r s c h g .
19 a, 13 [1964].
P . HARTECK, R . R . REEVES U. B . A . T H O M P S O N , Z . N a t u r f o r s c h g .
19 a, 2 [1964],
ist
F r e m d g a s e zu, so w i r d j e nach Art des zugesetzten
Frankfurt 32. 192 [1962]. 2
Kohlensuboxid
4
A . R . ANDERSON, J . V . F . BEST U. M . J . WILLETT, T r a n s .
raday Soc. 62, 595 [1966].
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