Reactivity of the binuclear ruthenium 'Pincer' complex [{RuCl2(η3-NN'N)}2(μ-N2)] towards N'donor ligands. The x-ray crystal structure of [RuCl2(η3-NN'n)(NCPh)] (NN'N= 2,6-bis[(dimethylamino)methyl]pyridine)

Article abstract of DOI:10.1016/S0020-1693(99)00610-6

Treatment of the binuclear, dinitrogen-bridged complex [{RuCl₂(η³-NN'N)}₂(μ-N₂)] (3, NN'N= 2,6-bis[(dimethylamino)methyl]pyridine) with two equivalents of acetonitrile gives the mononuclear derivative mer,trans-[RuCl₂(η³-NN'N)(NCMe)] (4), while the use of an excess of this ligand leads to the formation of the monocationic isomers mer,trans-[RuCl(η³-NN'N)(NCMe)₂]Cl (5) and mer,cis-[RuCl(η³-NN'N)(NCMe)₂]Cl (6). In contrast, when 3 is treated with an excess of benzonitrile or pyridine, the only products formed are mer,trans-[RuCl₂(η³-NN'N)(NCPh)] (7) and mer,trans-[RuCl₂(η³-NN'N)(py)] (8; py = pyridine), respectively. The X-ray structures of 7 and related reactions with other N-donor ligands are reported. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(99)00610-6

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 300–302 (2000) 1094–1098
Note
Reactivity of the binuclear ruthenium ‘Pincer’ complex
3
[
{RuCl (h -NN%N)} (m-N )] towards N-donor ligands. The X-ray
2
2
2
3
crystal structure of [RuCl (h -NN%N)(NCPh)]
NN%N=2,6-bis[(dimethylamino)methyl]pyridine)
2
(
a
a,b
a,1
b,2
Ignacio del R ´ı o , Stephan Back , Milja S. Hannu , Gerd Rheinwald ,
b
a,
Heinrich Lang , Gerard van Koten *
a
Department of Metal-Mediated Synthesis, Debye Institute, Utrecht Uni6ersity, Padualaan 8, 3584 CH Utrecht, The Netherlands
b
Technische Uni6ersit a¨ t Chemnitz, Institut f u¨ r Chemie, Lehrstuhl Anorganische Chemie, Strasse der Nationen 62, D-09111 Chemnitz, Germany
Received 13 September 1999; accepted 10 December 1999
Abstract
3
Treatment of the binuclear, dinitrogen-bridged complex [{RuCl (h -NN%N)} (m-N )] (3, NN%N=2,6-bis[(dimethy-
2
2
2
3
lamino)methyl]pyridine) with two equivalents of acetonitrile gives the mononuclear derivative mer,trans-[RuCl (h -
NN%N)(NCMe)] (4), while the use of an excess of this ligand leads to the formation of the monocationic isomers
2
3
3
mer,trans-[RuCl(h -NN%N)(NCMe) ]Cl (5) and mer,cis-[RuCl(h -NN%N)(NCMe) ]Cl (6). In contrast, when 3 is treated with an
2
2
3
3
excess of benzonitrile or pyridine, the only products formed are mer,trans-[RuCl (h -NN%N)(NCPh)] (7) and mer,trans-[RuCl (h -
2
2
NN%N)(py)] (8; py=pyridine), respectively. The X-ray structures of 7 and related reactions with other N-donor ligands are
reported. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Ruthenium complexes; Pincer complexes; N-donor ligands; X-ray crystal structure
1. Introduction
via the (cyclo)alkylation reaction of aromatic amines
with alcohols [2]. Complex 1 can easily lose chloride
In a recent publication, the synthesis and structural
anions in acetonitrile solution to form the monocationic
3
characterization of the Ru(II) ‘pincer’ complex mer,
derivative mer-[RuCl(h -NN%N)(PPh )(NCMe)]Cl (2)
3
3
trans-[RuCl (h -NN%N)(PPh )] (1) Scheme 1; NN%N=
(Scheme 1). This latter complex was shown to have an
enhanced catalytic activity when compared to its neu-
tral parent compound. The ease with which the dissoci-
ation of one of the two axial-positioned chloride
ligands takes place in 1, prompted us to propose this
process as the first step in the catalytic cycle when
2
3
2
,6-bis[(dimethylamino)methyl]pyridine) has been re-
ported [1]. This compound and a series of its cationic
derivatives have been proven to have potent catalytic
activity in the synthesis of piperidines and piperazines
*
Corresponding author. Tel.: +31-30-253 3120; fax: +31-30-252
615.
E-mail addresses: heinrich.lang@chemie.tu-chemnitz.de (H. Lang),
3
g.vankoten@chem.uu.nl (G. van Koten)
1
Exchange student from the University of Oulu, Finland.
Author to whom correspondence should be directed pertaining to
2
the crystallographic section of this manuscript.
Scheme 1.
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00610-6

I. del R ´ı o et al. / Inorganica Chimica Acta 300–302 (2000) 1094–1098
1095
3
complexes mer,trans-[RuCl(h -NN%N)(NCMe) ]Cl (5)
2
3
and mer,cis-[RuCl(h -NN%N)(NCMe) ]Cl (6) (Scheme
) is obtained. The structure of these two compounds in
solution can be determined by examination of their H
2
2
1
NMR spectra: complex 5 presents singlets for the ben-
zylic protons and for the NMe groups at l 3.98 and
2
2
.49, respectively, while the signal corresponding to the
Fig. 1.
acetonitrile ligands also appears as a singlet at l 2.29.
According to the structure proposed in Scheme 2 all
these data also indicate a C26 symmetry for this com-
plex in solution. Complex 5 can not be separated from
this mixture and slowly isomerizes in solution at r.t. or
upon heating of the reaction mixture to afford exclu-
sively compound 6. The asymmetry of 6 is reflected in
this species is used as catalyst precursor for this (cy-
clo)alkylation reaction. The loss of a chloride ligand in
1
would result in the formation of an unsaturated
species which upon coordination of a substrate
molecule would initiate the catalytic process.
In addition to this, a key step in the catalytic (cyclo)-
alkylation reaction of amines with alcohols is the reac-
tion of the active Ru center with the amine substrate.
Although this process has been proposed to occur prior
to the rate determining step of the catalytic cycle [2,3],
well-defined species arising from the reaction of the Ru
center with the reacting amine have not been isolated
and their nature remains obscure. In order to obtain a
better knowledge about this type of complexes, the
reactivity of the related Ru(II) dinitrogen-bridged binu-
1
its H NMR spectrum, showing a simple AB pattern
for the benzylic protons at l 4.25 and 3.88 and two
singlets for the NMe groups at l 2.60 and 2.53. The
2
signals corresponding to the two asymmetric acetoni-
trile ligands appear as singlets at l 2.46 and 2.39. The
13
1
C{ H} NMR data of this complex also corroborate
the structure proposed for 6.
One can assume the coordination of the first acetoni-
trile ligand to take place in the position which was
3
clear complex [{RuCl (h -NN%N)} (m-N )] (3) (Fig. 1)
previously occupied by the bridging N molecule to
2
2
2
2
towards N-donor ligands has been studied. The work
reported herein shows that 3 readily reacts with N-
donor ligands such as nitriles or pyridine to yield the
corresponding mononuclear neutral or cationic deriva-
tives. In contrast, treatment of 3 with primary or
secondary amines leads to the formation of complex
mixtures of products.
afford 4. The second step would imply a dissociation
process of one of the chloride ligands to form a 16-elec-
tron unsaturated species. This is not surprising, since
related electron-deficient compounds have been isolated
previously [1,5a]. Further reaction of this species with
the second molecule of acetonitrile would result in the
formation of 5, which finally would undergo an isomer-
ization reaction to afford 6. The reason for this isomer-
ization process may be electronic in nature, since the
steric hindrance of both chloride and acetonitrile lig-
ands is similar.
2. Results and discussion
3
The recently reported binuclear complex [{RuCl (h -
In contrast to the reaction with acetonitrile, when 3 is
treated with either stoichiometric amounts or with an
2
NN%N)} (m-N )] (3) can be obtained in a high yield by
2
2
the simple treatment of [RuCl (nbd)] (nbd=1,5-nor-
excess of benzonitrile, a neutral compound, i.e.,
2
n
3
bornadiene) with the terdentate ‘pincer’ ligand under a
dinitrogen atmosphere [1]. Compound 3 is very reactive
under mild conditions towards a vast array of neutral
donor ligands such as phosphines [4], CO [1], alkynes
and alkenes [5] and sulfur containing nucleophiles [6].
When a dichloromethane solution of 3 is treated with
mer,trans-[RuCl (h -NN%N)(NCPh)] (7) (Scheme 2) is
2
obtained. The synthesis of 7 had been described in a
previous study, and its structure in solution has been
suggested on the bases of its NMR and IR data [7]. To
further confirm that this structural motif is retained in
the solid state, a single crystal X-ray diffraction study
3
2
equiv. of acetonitrile, the mononuclear derivative
was carried out . This study revealed that the general
3
mer,trans-[RuCl (h -NN%N)(NCMe)] (4) (Scheme 2) is
obtained in good yields. The molecular structure de-
picted for 4 (Scheme 2) is strongly supported by its H
2
3
Crystal and refinement data for 7·C H : orange plates, 0.6×
6 6
1
0.4×0.2 mm; formula: C H Cl N Ru·C H ; MW=546.49; a=
18 24 2 4 6 6
3
8
.317(2), b=27.274(4), c=10.973(3) A; i=90°; V=2489.0(9) A ;
, ,
orthorhombic, space group Pbcn, Z=4; Temperature=173(2) K;
NMR spectrum which shows the resonance signals
corresponding to the CH and NMe groups of the
2
2
BRUKER SMART CCD diffractometer with fine focus tube (Mo, u=
pyridine ligand as singlets at l 3.99 and 2.53, respec-
tively. This strongly suggests the C symmetry of the
complex. Its C{ H} NMR data (see Section 3) are
also in accordance with the structure proposed for 4.
When an acetonitrile solution of 3 is stirred at r.t. for
0.71073 A, graphite monochromator); ꢀ-scans; 15414 measured
,
reflections, 3496 unique reflections; 204 parameters; R (F, observed
1
2
6
2
1
3
1
reflections)=0.0376; wR (F , all reflections)=0.0769; structure solu-
2
tion with SHELXS-97 [9a]; structure refinement with SHELXL-97 [9b].
Structure graphics and checking for higher symmetry were performed
with the program PLATON [10]. Absorption correction (0.53–0.81
transmission range) has been done using SADABS [11].
30 min, a 2:1 mixture of the monocationic isomeric

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I. del R ´ı o et al. / Inorganica Chimica Acta 300–302 (2000) 1094–1098
Scheme 2. (i) 2 equiv. NCMe, CH Cl , r.t. (ii) Excess NCMe, r.t. (iii) Excess NCMe, reflux, 30 min. (iv) 2 equiv. pyridine, THF, r.t. (v) 2 equiv.
2
2
NCPh, THF, r.t.
structure suggested in solution is also found in the solid
state. A molecular plot of 7 is depicted in Fig. 2 with
pertinent bond lengths and angles listed in the figure
caption. The Ru atom is hexacoordinated in a distorted
octahedral ligand environment with the three N-donor
atoms positioned in a meridional configuration. In con-
trast to the perfect meridional geometry, 7 possesses no
mirror plane, because of the non-planarity of the NN%N
ligand. Additionally, there is an interplanar angle of
nitrogen atom, positioned trans to the pyridine nitrogen
atom, a situation which forces the two chloride ligands
to be positioned trans to each other. Bond lengths and
angles are typical when compared with related struc-
tures [1,4,5a,6,8]. Full structural details can be found in
Section 5.
Treatment of a THF solution of 3 with 2 equiv. of
pyridine affords the neutral derivative mer,trans-
3
[RuCl
(h -NN%N)(py)] (8) Scheme 2; py=pyridine). Its
2
1
13
1
34.8(2)° of the pyridine ring to the benzyl ring of the
H and C{ H} NMR data are listed in Section 3.
These data reflect the symmetry of the complex and
strongly support the structure proposed for 8 in Scheme
benzonitrile ligand, which also breaks the mirror sym-
metry. The benzonitrile ligand is |-coordinated via the
2
. Similar treatment of 3 with other N-donor ligands
such as aniline, allylamine or ammonia led to the
formation of complex mixtures from which no pure
compound could be isolated. Hydride-containing spe-
1
cies were observed by H NMR in the reaction
mixtures.
3
. Experimental
3.1. General data
Solvents were dried over sodium benzophenone ketyl
(
THF, hydrocarbons) or CaH (CH Cl , NCMe) and
2 2 2
Fig. 2. Molecular structure of compound 7. Displacement ellip-
soids are drawn at the 50% probability level. Selected bond distan-
,
ces (A), angles and torsion angles (°): Ru(1)ꢀCl(1), 2.4265(7); Ru(1)ꢀ
Cl(1a), 2.4265(7); Ru(1)ꢀN(1), 1.969(2); Ru(1)ꢀN(2), 2.185(2);
Ru(1)ꢀN(2a), 2.185(2); Ru(1)ꢀN(3), 2.007(3); N(3)ꢀC(7), 1.141(4);
C(7)ꢀC(8), 1.435(4); Cl(1)ꢀRu(1)ꢀCl(1a), 177.31(3); Cl(1)ꢀRu(1)ꢀ
N(3), 88.656(16); Cl(1a)ꢀRu(1)ꢀN(3), 88.656(16); N(1)ꢀRu(1)ꢀN(2),
distilled under a nitrogen atmosphere prior to use. All
reagents were obtained from commercial sources and
were used without further purification. Complexes 1
and 3 were prepared as described previously [1]. H
(
1
13
1
200.133 and 300.103 MHz) and C{ H} (50.323 and
7
5.453 MHz) NMR spectra were recorded at 298 K
79.92(5); N(1)ꢀRu(1)ꢀN(2a), 79.92(5); N(1)ꢀRu(1)ꢀN(3), 180.0;
with either a Bruker AC-200 or an AC-300 instrument,
using SiMe as internal standard (lH or l =0.00).
Ru(1)ꢀN(3)ꢀC(7), 180.0; N(3)ꢀC(7)ꢀC(8), 180.0; N(1)ꢀC(1)ꢀC(4)ꢀ
N(2), −31.8(3).
4
C

I. del R ´ı o et al. / Inorganica Chimica Acta 300–302 (2000) 1094–1098
1097
Microanalyses were obtained from H. Kolbe Mikroan-
alytisches Laboratorium (Germany).
solvent was decanted. The solid residue was dried un-
der reduced pressure to give 7 as a brown solid (178
mg, 95%). Its analytical and spectroscopic data
matched those reported in the literature [7].
3
3
.2. Synthesis of mer,trans-[RuCl (p -NN%N)(NCMe)]
2
(
4)
3
3
.5. Synthesis of mer,trans-[RuCl (p -NN%N)(py)] (8)
2
A solution of 3 (70 mg, 0.092 mmol) and MeCN (9.7
ml, 0.185 mmol) in CH Cl (20 ml) was stirred at r.t.
2
2
A solution of 3 (100 mg, 0.132 mmol) and pyridine
21.3 ml, 0.264 mmol) in THF (30 ml) was stirred at r.t.
for 30 min. The colour changed from orange to red.
The solvent was removed under reduced pressure and
the solid residue was washed with pentane (2×10 ml)
to give 4 as a brown solid (60 mg, 80%). Anal. Calc.
for C H Cl N Ru (406.4): C, 38.43; H, 5.46; N,
(
for 60 min. The colour changed from orange to red.
The solvent was removed under reduced pressure and
the solid residue was washed with pentane (2×10 ml)
to afford 8 as a brown solid (110 mg, 94%). Anal. Calc.
for C H Cl N Ru (444.4): C, 43.24; H, 5.44; N,
1
3
22
2
4
1
1
3.79. Found: C, 38.80; H, 5.67; N, 13.41%. H NMR
1
6
24
2
4
(
CDCl ): 7.40 (t, J= 7.8, 1H, ArH), 7.13 (d, J=7.8,
1
3
1
(
7
4
(
(
2.61. Found: C, 43.99; H, 5.78; N, 12.23%. H NMR
2
2
1
H, ArH), 3.99 (s, 4H, CH ), 2.69 (s, 3H, NCMe),
2
1
CDCl ): 9.65 (m, 2H, py), 7.70 (t, J=7.8, 1H, ArH),
3
3
1
.53 (s, 12H, NMe ) ppm. C{ H} NMR (CDCl ):
2
3
.35 (m, 3H, py), 7.16 (d, J=7.8, 2H, ArH), 4.03 (s,
64.8, 132.3, 118.9 (ArC’s), 71.9 (CH ), 54.6 (NMe ),
13
1
2
2
H, CH ), 2.28 (s, 12H, NMe ) ppm. C{ H} NMR
2
2
(
NN%N ligand); 123.5 (CH CN), 5.4 (CH CN) ppm.
3 3
CDCl ): 163.2, 130.4, 118.2 (ArC’s), 72.1 (CH ), 53.6
3
2
NMe ), (NN%N ligand); 156.4, 133.6, 123.5 (py ligand)
2
3
.3. Synthesis of
ppm.
3
mer,trans-[RuCl(p -NN%N)(NCMe) ]Cl (5) and
mer,cis-[RuCl(p -NN%N)(NCMe) ]Cl (6)
2
3
2
4
. Conclusions
A solution of 3 (50 mg, 0.066 mmol) in NCMe (30
ml) was stirred at r.t. for 30 min. The colour changed
from pale to dark orange. The solvent was removed
The reactivity of the dinitrogen-bridged complex
3
1
[{RuCl (h -NN%N)} (m-N )] towards some N-donor lig-
2
2
2
under reduced pressure and the residue analyzed by H
ands has been studied. Chloride ligand dissociation
from 3 in acetonitrile solutions has been proven to be
an easy process, in accordance with the data observed
previously for similar complexes [2]. In contrast, treat-
ment of 3 with an excess of benzonitrile does not lead
to chloride dissociation but to the formation of the
neutral derivative 7 as the only detected product. This
might be due to the different electron-donating proper-
ties of both ligands, since their steric hindrances are
similar. The X-ray crystal structure of 7 has been
determined. The high instability of the products arising
from the reaction of 3 with aniline or other primary
amines may be the reason for the high catalytic activity
shown by these metal fragments when they are used as
precursors in the (cyclo)alkylation reactions with alco-
hols. Unfortunately, these species could not be iso-
lated.
NMR, showing a 2:1 mixture, respectively, of the iso-
mers 5 and 6. The residue was then redissolved in 30
ml of NCMe and heated to reflux temperature for 30
min. The solvent was then removed under reduced
pressure and the residue washed with pentane (2×20
ml) to give 6 as a red solid (52 mg, 89%). Anal. Calc.
for C H Cl N Ru (447.4): C, 40.27; H, 5.63; N,
1
5
25
2
5
1
15.65. Found: C, 39.80; H, 5.35; N, 15.91%. H NMR
data for 5 (CDCl ): 7.49 (t, J=7.8, 1H, ArH), 7.25 (d,
3
J=7.8, 2H, ArH), 3.98 (s, 4H, CH ), 2.49 (s, 12H,
2
1
NMe ), 2.29 (s, 6H, NCMe) ppm. H NMR data for 6
2
(
CD CN): 7.71 (t, J=7.8, 1H, ArH), 7.38 (d, J=7.8,
3
2
1
H, ArH), 4.25 (d, J=15.4, 2H, CH ), 3.88 (d, J=
2
5.4, 2H, CH ), 2.60 (s, 6H, NMe ), 2.53 (s, 6H,
2
2
NMe ), 2.46 (s, 3H, NCMe), 2.39 (s, 3H, NCMe) ppm.
2
1
3
1
C{ H} NMR (CD CN): 162.5, 135.2, 120.2 (ArC’s),
3
7
2.0 (CH ), 54.1 (NMe ), 53.6 (NMe ), (NN%N ligand);
2
2
2
1
29.5 (CH CN), 125.0 (CH CN), 4.8 (CH CN), 3.8
3
3
3
(
CH CN) ppm.
3
5
. Supplementary material
3
3
.4. Synthesis of mer,trans-[RuCl (p -NN%N)(NCPh)]
2
(
7)
Crystallographic data for the structure of complex 7
have been deposited with the Cambridge Crystallo-
graphic Data Centre as supplementary publication no.
CCDC 112403. Copies of the data can be obtained on
application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK (fax: +44-1223-336033 or e-mail:
deposit@ccdc.cam.ac.uk).
A solution of 3 (150 mg, 0.2 mmol) and PhCN (40
mg, 0.4 mmol) in THF (30 ml) was stirred at r.t. for 60
min. The colour changed from orange to red. The
solvent was removed under reduced pressure to ap-
proximately 5 ml; 50 ml of pentane were added and the

1098
I. del R ´ı o et al. / Inorganica Chimica Acta 300–302 (2000) 1094–1098
[
4] I. del R ´ı o, R.A. Gossage, M. Lutz, A.L. Spek, G. van Koten, J.
Acknowledgements
Organomet. Chem. 583 (1999) 69.
[
5] (a) I. del R ´ı o, R.A. Gossage, M. Hannu, M. Lutz, A.L. Spek, G.
van Koten, Organometallics 18 (1999) 1097. (b) I. del R ´ı o, G.
van Koten, Tetrahedron Lett. 40 (1999) 1401.
This work was supported by the Council for Chemi-
cal Sciences of the Netherlands Organization for Scien-
tific Research (CW-NWO) and the Volkswagenstiftung,
the Fonds der Chemischen Industrie. We thank the
European Union for a Post-doctoral grant (IdR) under
the auspices of the Training and Mobility of Re-
searchers Program (ERBFMBICT961634) and for an
under-graduate grant (MSH) under the Erasmus
Program.
[6] I. del R ´ı o, R.A. Gossage, M. Lutz, A.L. Spek, G. van Koten,
Inorg. Chim. Acta 287 (1999) 113.
[
7] S. Back, R.A. Gossage, I. del R ´ı o, G. Rheinwald, H. Lang, G.
van Koten, J. Organomet. Chem. 582 (1999) 126.
[
8] See, for example: (a) J.-P. Sutter, S.L. James, P. Steenwinkel, T.
Karlen, D.M. Grove, N. Veldman, W.J.J. Smeets, A.L. Spek, G.
van Koten, Organometallics 15 (1996) 941. (b) P. Steenwinkel,
S.L. James, N. Veldman, H. Kooijman, A.L. Spek, D.M. Grove,
G. van Koten, Chem. Eur. J. 2 (1996) 1440. (c) L. Barloy, S.Y.
Ku, J.A. Osborn, A. De Cian, J. Fischer, Polyhedron 16 (1997)
2
91. (d) N. Rahmouni, J.A. Osborn, A. De Cian, J. Fischer, A.
Ezzamarty, Organometallics 17 (1998) 2470. (e) P. Steenwinkel,
R.A. Gossage, G. van Koten, Chem. Eur. J. 4 (1998) 759 and
Refs. therein. (f) P. Steenwinkel, S. Kolmschot, R.A. Gossage, P.
Dani, N. Veldman, A.L. Spek, G. van Koten, Eur. J. Inorg.
Chem. (1998) 477.
References
[
1] R.A.T.M. Abbenhuis, I. del R ´ı o, M.M. Bergshoef, J. Boersma,
N. Veldman, A.L. Spek, G. van Koten, Inorg. Chem. 37 (1998)
1
749.
2] R.A.T.M. Abbenhuis, J. Boersma, G. van Koten, J. Org. Chem.
3 (1998) 4282.
[9] (a) G.M. Sheldrick SHELXS-97, Program for Crystal Structure
Solution, University of G o¨ ttingen, Germany, 1997. (b) G.M.
Sheldrick SHELXL-97, Program for Crystal Structure Refinement,
University of G o¨ ttingen, Germany, 1997.
[10] A.L. Spek, PLATON, Program for Crystal Structure Calculations,
University of Utrecht, The Netherlands, 1998.
[
[
6
3] See for example: (a) Y. Watanabe, Y. Tsuji, Y. Ohsugi, T. Ohta,
J. Org. Chem. 49 (1984) 3359. (b) Y. Tsuji, K.-T. Huh, Y.
Ohsugi, Y. Watanabe, J. Org. Chem. 50 (1985) 1365. (c) S.
Ganguly, F.L. Joslin, D.M. Roundhill, Inorg. Chem. 28 (1989)
[11] Area-Detector Absorption Correction, Siemens Industrie Au-
tomation, Madison, WI, 1996.
4
562.
.