Diazald: An entry to diruthenium complexes containing bridging nitrosyl ligands

Article abstract of DOI:10.1016/j.jorganchem.2013.08.017

Reactions of coordinatively unsaturated complexes [Ru₂(μ- P^tBu₂)(μ-H)(μ-PP)(CO)₄] (PP = bisphosphanes, N,N-substituted bis(diphenylphosphanyl)amines) with the nitrosylating reagent diazald (N-methyl-Nnitroso- p-toluenesulfonamide) were investigated. Thus a convenient synthesis affording a series of new diruthenium complexes containing bridging nitrosyl ligands of the general type [Ru ₂(μ-P^tBu₂)(μ-NO)(μ- PP)(CO) ₄] was developed and the crystal and molecular structures of five new compounds were determined. Contrary, this reaction principle does not work for the closely related complex [Fe₂(μ-P^tBu ₂)(μ-H)(μ-dppm)(CO)₄] (dppm = Ph₂PCH ₂PPh₂). In this case carbon monoxide was produced in side reactions and the known compound [Fe₂(μ-P^tBu ₂)(μ-H)(μ-dppm)(μ-CO)(CO)₄] was obtained as the main product. The molecular structure of the latter complex was also determined by X-ray diffraction.

Full text of DOI:10.1016/j.jorganchem.2013.08.017

Journal of Organometallic Chemistry 751 (2014) 368e373
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Diazald: An entry to diruthenium complexes containing bridging
nitrosyl ligandsq
*
Tobias Mayer, Peter Mayer, Hans-Christian Böttcher
Department of Chemistry, Ludwig Maximilian University, Butenandtstraße 5ꢀ13, 81377 Munich, Germany
a r t i c l e i n f o
a b s t r a c t
-PtBu2)(
m
-H)(
m
-P^P)(CO)4] (P^P ¼ bisphosphanes,
Article history:
Reactions of coordinatively unsaturated complexes [Ru2(
N,N-substituted bis(diphenylphosphanyl)amines) with the nitrosylating reagent diazald (N-methyl-N-
nitroso-p-toluenesulfonamide) were investigated. Thus a convenient synthesis affording a series of new
m
Received 28 May 2013
Received in revised form
5 August 2013
diruthenium complexes containing bridging nitrosyl ligands of the general type [Ru2(
P^P)(CO)4] was developed and the crystal and molecular structures of five new compounds were deter-
mined. Contrary, this reaction principle does not work for the closely related complex [Fe2(
-PtBu2)(
H)(
-dppm)(CO)4] (dppm ¼ Ph2PCH2PPh2). In this case carbon monoxide was produced in side reactions
and the known compound [Fe2( -H)( -dppm)( -CO)(CO)4] was obtained as the main product.
-PtBu2)(
The molecular structure of the latter complex was also determined by X-ray diffraction.
Ó 2013 Elsevier B.V. All rights reserved.
m m-NO)(m-
-PtBu2)(
Accepted 8 August 2013
m
m-
Keywords:
Ruthenium
Coordinative unsaturation
Nitrosyl ligands
Phosphanido-bridged
Crystal structure
m
m
m
m
m
1. Introduction
coordinatively unsaturated diiron complex [Fe2(m m-H)(m-
-PtBu2)(
dppm)(CO)4] (3) [15].
Recently we reported the synthesis and X-ray crystal struc-
tures of some new coordinatively unsaturated complexes [Ru2(
PtBu2)(
-H)(
-P^P)(CO)4] (P^P ¼ bisphosphanes or N,N-substituted
bis(diphenylphosphanyl)amines) [1]. Because of the unsaturated
character of the central Ru2( -H) moiety these complexes exhibit
m-
2. Experimental
m
m
2.1. General considerations
m
an enhanced reactivity towards a great variety of small molecules
under mild conditions [2e13]. During these investigations we
found that the nitrosyl ligand can be introduced conveniently in
All preparative operations were performed under a dry nitrogen
atmosphere using conventional Schlenk techniques. Solvents were
dried over sodium-benzophenone ketyl or molecular sieves. The
compounds 1aef [1,12] and 3 [15] were prepared as reported in the
literature. Chemicals were purchased commercially from Aldrich. IR
spectra were recorded from solid samples with a JASCO FT/IR-460
plus spectrometer equipped with an ATR unit. NMR spectra were
obtained using a Jeol Eclipse 270 instrument operating at 270 (1H)
and at 109 MHz (31P), respectively. Chemical shifts are given in ppm
from SiMe4 (1H), and 85% H3PO4 (31P). Microanalyses (C, H, N) were
performed by the Microanalytical Laboratory of the Department of
Chemistry, LMU Munich, using a Heraeus Elementar Vario EI
instrument.
the dimetal core of [Ru2(m m-H)(m-dppm)(CO)4] (1,
-PtBu2)(
dppm ¼ Ph2PCH2PPh2) by the substitution of the hydrido ligand
towards NO using the nitrosylating reagent diazald (N-methyl-N-
nitroso-p-toluenesulfonamide). Thus the complex [Ru2(
m-
PtBu2)(
m
-NO)( -dppm)(CO)4] (2) was obtained in good yields [9].
m
The compound diazald was described in the literature as a useful
selective nitrosylating agent especially in reactions with com-
plexes containing hydrido ligands [14]. Now we examined this
synthetic pathway for a series of other dinuclear unsaturated
hydrido complexes and we describe therein the synthesis and the
molecular structures of some new diruthenium complexes con-
taining bridging nitrosyl ligands. Surprisingly this reaction
principle was not successful in the case of the closely related
2.2. Synthesis of [Ru2(
m
-PtBu2)(
m-NO)(m-P^P)(CO)4] (P^P ¼ dmpm,
2a; dcypm, 2b; dppen, 2c; dppa, 2d; dpppra, 2e; dpppha, 2f)
A mixture of the corresponding diruthenium complex 1aef
(0.5 mmol) and N-methyl-N-nitroso-p-toluenesulfonamide (322 mg,
1.5 mmol) in diethyl ether (40 mL) was stirred for 48 h at room
q
Contribution to the Special Issue of the 50th Anniversary.
* Corresponding author. Tel.: þ49 89218077422; fax: þ49 89218077407.
E-mail address: hans.boettcher@cup.uni-muenchen.de (H.-C. Böttcher).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.08.017

T. Mayer et al. / Journal of Organometallic Chemistry 751 (2014) 368e373
369
temperature. During this time the color of the solution changed from
violet to green. The resulting solution was evaporated to dryness
under reduced pressure. The remaining residue was dissolved in
toluene and filtered over alumina using toluene as the eluent. The
solvent was removed in vacuo and the products were crystallized
from acetone/water (1:3) affording deep green crystals.
green color of the solution was changed to redebrown. The so-
lution was stirred for additional 15 h and the solvent was
removed under reduced pressure. (During this procedure, the
liquid in the vacuum trap adopted an orange color. In the liquid
the presence of the volatile [Fe(CO)2(NO)2] was indicated by IR
spectroscopy.) The remaining residue was extracted three times
with 10 mL portions of diethyl ether. The combined extracts were
filtered over a short column of alumina with diethyl ether as the
eluent affording an orangeebrown band. The investigation of this
fraction by 31P NMR spectroscopy showed unambiguously the
presence of complex 5 (traces) and 4, respectively [18,15]. Finally,
compound 4 was obtained by crystallization from CH2Cl2/ethanol
as orangeebrown crystals suitable for X-ray diffraction. Yield:
172 mg (44%). Anal. Calcd for C38H41Fe2O5P3 (782.36): C, 58.34;
2a: Yield: 234 mg (75%). Anal. Calcd for C17H32NO5P3Ru2
(625.51): C, 32.64; H, 5.16; N, 2.24. Found: C, 32.41; H, 5.19; N,
2.02%. IR (solid):
(270 MHz, CD2Cl2):
n
(CO): 1963s, 1916vs,
n
(
m
-NO): 1488s. 1H NMR
3
t
d
1.80 (d, JPH ¼ 14.0 Hz, 9H, Bu), 1.59 (m, 2H,
CH2), 1.56 (m, 6H, CH3), 1.47 (m, 6H, CH3), 0.88 (d, 3JPH ¼ 14.0 Hz, 9H,
tBu). 31P{1H} NMR (109 MHz, CD2Cl2):
d
207.7 (t, 2JPP ¼ 130.3 Hz,
m-
PtBu2), 12.1 (d, 2JPP ¼ 130.3 Hz,
m-dmpm). Suitable single crystals of
2a for X-ray diffraction were obtained from water/acetone at
ambient temperatures by slow evaporation during 3 days.
2b: Yield: 278 mg (62%). Anal. Calcd for C37H64NO5P3Ru2
(897.98): C, 49.49; H, 7.18; N, 1.56. Found: C, 49.36; H, 7.32; N, 1.34%.
H, 5.28. Found: C, 58.12; H, 5.33%. 31P{1H} NMR (109 MHz,
2
CD2Cl2):
d
240.0 (t, JPP
¼
42.8 Hz, m
-PtBu2), 74.2 (d,
2JPP ¼ 42.8 Hz,
m
-dppm). The 1H NMR and IR data were reported
IR (solid):
n
(CO): 1980s, 1949vs, 1920vs, 1904vs,
n
(m
-NO): 1487s. 1H
elsewhere [15].
NMR (270 MHz, CD2Cl2):
d
1.84 (d, 3JPH ¼ 13.6 Hz, 9H, tBu),1.62e1.01
(m, 44H, Cy), 1.27 (m, 2H, CH2), 0.94 (d, 3JPH ¼ 13.5 Hz, 9H, tBu). 31
P
2.4. X-ray structural determination
{1H} NMR (109 MHz, CD2Cl2):
d
216.4 (t, JPP ¼ 126.8 Hz,
m
-PtBu2),
2
55.1 (d, 2JPP ¼ 126.8 Hz,
m-dcypm). Suitable single crystals of 2b for
Suitable single crystals for X-ray diffraction of the compounds
2aed and 2f were obtained as described in the experimental sec-
tion. Crystals were selected by means of a polarization microscope,
mounted on the tip of a glass fiber, and investigated on a Bruker
Nonius-Kappa CCD diffractometer (2aec, 2f, and 4) and on an
X-ray diffraction were obtained by slow diffusion of ethanol into a
dichloromethane solution at room temperature within 3 days.
2c: Yield: 319 g (72%). Anal. Calcd for C38H40NO5P3Ru2 (885.80):
C, 51.53; H, 4.55; N,1.58. Found: C, 51.36; H, 4.82; N,1.24%. IR (solid):
n
(CO): 1972s, 1945vs, 1933vs, 1906s, n(m
-NO): 1490s. 1H NMR
Oxford XCalibur diffractometer (2d), respectively, using Mo-K
a
7.38e7.12 (m, 20H, Ph), 6.27 (t, 3JPH ¼ 20.5 Hz,
ꢀ
(270 MHz, CD2Cl2):
d
radiation (
l
¼ 0.71073 A). The structures were solved by direct
2H, C]CH2), 1.93 (d, 3JPH ¼ 14.0 Hz, 9H, tBu), 1.01 (d, 3JPH ¼ 14.0 Hz,
methods (SHELXS) [16] and refined by full-matrix least-squares
calculations on F2 (SHELXL-97) [17]. The position of the hydrido
ligand in compound 4 has been located from the difference map.
Details of the crystal data, data collection, structure solution, and
refinement parameters of the new compounds are summarized in
Table 1 (2aec) and Table 2 (2d, 2f, and 4), respectively.
9H, tBu). 31P{1H} NMR (109 MHz, CD2Cl2):
d
211.3 (t, 2JPP ¼ 127.9 Hz,
m
-PtBu2), 41.7 (d, 2JPP ¼ 127.9 Hz,
m-dppen). Suitable single crystals
of 2c for X-ray diffraction were obtained from water/acetone at
ambient temperatures by slow evaporation within 3 days.
2d: Yield: 284 mg (65%). Anal. Calcd for C36H39N2O5P3Ru2
(874.78): C, 49.43; H, 4.49; N, 3.20. Found: C, 49.36; H, 4.72; N,
3.44%. IR (solid): n(CO): 2032m, 2007s, 1972vs, 1939s, n(m-NO):
1551vs. 1H NMR (270 MHz, CD2Cl2):
d 7.47e7.31 (m, 20H, Ph), 1.54
Table 1
Crystal data and structure refinement details for compounds 2aec.
(d, 3JPH ¼ 14.2 Hz, 9H, tBu), 1.05 (d, 3JPH ¼ 14.2 Hz, 9H, tBu). 31P{1H}
224.1 (t, 2JPP ¼ 111.6 Hz,
m
-PtBu2), 76.9 (d,
Compound
2a
2b
2c$1.5 acetone
NMR (109 MHz, CD2Cl2):
d
2JPP ¼ 111.6 Hz,
m-dppa). Suitable single crystals of 2d for X-ray
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C17H32NO5P3Ru2 C37H64NO5P3Ru2 C42.5H49NO6.5P3Ru2
625.9
897.94
173(2)
972.88
173(2)
diffraction were obtained from water/acetone at ambient temper-
atures by slow evaporation within 3 days.
173(2)
Orthorhombic
Pnma
14.9069(6)
14.9333(6)
11.1729(5)
90
Monoclinic
P21/c
18.1026(2)
18.2483(2)
12.78950(10)
90
104.1180(10)
90
4097.29(7)
4
Monoclinic
P21/c
16.6252(2)
13.6152(2)
18.7877(3)
90
93.2720(10)
90
4245.77(11)
4
2e: Yield: 210 mg (46%). Anal. Calcd for C39H45N2O5P3Ru2
(916.86): C, 51.09; H, 4.95; N, 3.06. Found: C, 50.86; H, 4.82; N,
ꢀ
a (A)
ꢀ
b (A)
2.91%. IR (solid):
n
(CO): 2026s, 1966s, 1944s, 1921vs,
n(m-NO):
ꢀ
c (A)
1615m. 1H NMR (270 MHz, CD2Cl2):
d
7.63e7.31 (m, 20H, Ph), 3.70
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
3
(m, 2H, NCH2), 2.55 (m, 2H, CH2CH3), 1.77 (d, JPH ¼ 14.0 Hz, 9H,
90
90
tBu), 0.88 (d, 3JPH ¼ 14.0 Hz, 9H, tBu), 0.13 (m, 3H, CH2CH3). 31P{1H}
3
ꢀ
213.9 (t, 2JPP ¼ 129.1 Hz,
m
-PtBu2), 104.6
Volume (A )
Z
2487.19(18)
4
1.670
NMR (109 MHz, CD2Cl2):
d
(d, 2JPP ¼ 129.1 Hz,
m-dpppra).
rcalcd (g cmꢀ3
)
1.456
0.894
1.522
0.872
m
/mmꢀ1
1.433
2f: Yield: 96 mg (20%). Anal. Calcd for C42H43N2O5P3Ru2
(950.88): C, 53.05; H, 4.56; N, 2.95. Found: C, 52.86; H, 4.82; N,
q
range for data
3.29e27.48
3.21e27.56
3.18e27.49
2.71%. IR (solid): n(CO): 2026s, 1932s, n(m
-NO): 1595m. 1H NMR
collection (ꢁ)
7.85e6.79 (m, 25H, Ph), 1.37 (d, 3JPH ¼ 14.5 Hz,
Reflections
measured
Rint
Observed reflections 2948
Reflections, unique
Parameters/
16,607
0.1243
35,193
32,845
(270 MHz, CD2Cl23):
d
t
t
9H, Bu), 1.08 (d, JPH ¼ 13.2 Hz, 9H, Bu). 31P{1H} NMR (109 MHz,
0.0343
9423
18,382
453/0
0.0332
9723
17,748
524/0
2
CD2Cl2):
d
221.1 (t, JPP
¼
133.8 Hz, m
-PtBu2), 104.7 (d,
2JPP ¼ 133.8 Hz,
m-dpppha). Suitable single crystals of 2f for X-ray
9076
156/0
diffraction were obtained from water/acetone at ambient temper-
atures by slow evaporation within 3 days.
restraints
R (Fobs
)
0.0421
0.0956
1.060
0.0312
0.0777
1.039
0.0279
0.0605
1.067
Rw (F2)
2.3. Reaction of [Fe2(m m-H)(m-dppm)(CO)4](3) with diazald
-PtBu2)(
S
Max electron
0.830
0.555
0.642
ꢀꢀ3
density (e A
Min electron
)
Compound 3 (377 mg, 0.5 mmol) was dissolved in diethyl
ether (30 mL), diazald (322 mg, 1.5 mmol) was added and the
resulting solution stirred at room temperature. After 5 h the deep
ꢀ0.606
ꢀ0.516
ꢀ0.605
ꢀꢀ3
density (e A
)

370
T. Mayer et al. / Journal of Organometallic Chemistry 751 (2014) 368e373
Table 2
temperature over longer periods afforded the products in a cleaner
manner. The new compounds 2aef were characterized by standard
spectroscopic methods (see Experimental section). In the IR spectra
beside the characteristic carbonyl vibration bands in each case a
band corresponding to the bridging nitrosyl ligand was found. For
the complexes bearing the bisphosphane ligands (2aec) this band
is situated in the average at 1488 cmꢀ1 whereas for the compounds
containing the N,N-substituted bis(diphenylphosphanyl)amines
(2def) this band was found in the average at 1587 cmꢀ1. This is in
accordance with the higher electron-donating properties of the
bisphosphane ligands. The same trend is observed for the CO
stretching frequencies of the carbonyl ligands. At this point we have
Crystal data and structure refinement details for compounds 2d, 2f, and 4.
Compound
2d
2f
4
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C36H39NO5P3Ru2 C42H43NO5P3Ru2 C38H41Fe2O5P3
874.74
173(2)
triclinic
P 1
9.0261(8)
12.1578(18)
18.209(2)
87.687(11)
85.056(9)
69.726(12)
1867.3(4)
2
950.83
173(2)
triclinic
P 1
12.5167(4)
12.5406(4)
15.1164(5)
80.081(2)
67.870(2)
68.147(2)
2038.62(11)
2
782.34
200(2)
triclinic
P 1
19.7861(4)
19.8314(4)
20.6476(4)
96.118(2)
97.730(1)
110.239(1)
7429.7(3)
8
ꢀ
a (A)
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
3
ꢀ
Volume (A )
Z
to correct the reported value for the n(m-NO) band of the parent
complex [Ru2(m m-NO)(m-dppm)(CO)4] (1) [9]. There we re-
-PtBu2)(
rcalcd (g cmꢀ3
)
1.556
0.980
4.19e26.25
1.549
0.905
3.29e27.50
1.399
0.951
3.19e25.74
ported
n
(
m
-NO) ¼ 1547 cmꢀ1 for the bridging nitrosyl ligand in 1;
m
/mmꢀ1
however this was not correct. Now we have redetermined the n(m-
q
range for
data collection (ꢁ)
NO) band of compound 1 at 1467 cmꢀ1 which is in very good
agreement with the observed ones of the related complexes in the
present work. The 31P{1H} NMR spectra of the new compounds 2ae
f showed in each case the typical doublet/triplet pattern indicating
the symmetric arrangement of the phosphanido group together
Reflections measured
Rint
Observed reflections
Reflections, unique
Parameters/restraints
18,569
0.0618
14,155
6278
440/0
0.0475
0.1329
1.004
17,517
0.0410
9225
51,392
0.0763
16,977
27,540
524/0
0.0574
0.1588
1.031
9343
487/0
0.0385
0.0883
1.031
0.763
R (Fobs
)
with the bridging m-P^P ligand. Suitable crystals of all new com-
Rw (F2)
pounds 2aef for X-ray diffraction studies were obtained and their
molecular structures could be confirmed (see below). The collected
data for the compound 2e were however only of lower quality, Rw
(F2) ¼ 0.2357, therefore these data were not deposited with the
CCDC.
S
Max electron
density (e A
Min electron
1.110
0.692
ꢀꢀ3
)
ꢀ0.811
ꢀ0.630
ꢀ0.466
ꢀꢀ3
density (e A
)
In light of our interest in studies including the related diiron
complexes we examined also the reaction of the coordinatively
3. Results and discussion
unsaturated complex [Fe2(m m-H)(m-dppm)(CO)4] (3) [15]
-PtBu2)(
with diazald. Surprisingly the principle of the described title reac-
tion was not successful in this case. Unexpectedly, the reaction
3.1. Preparation and characterization of new compounds 2aef
resulted in the formation of the known carbonyl complex [Fe2(
m-
Recently we found that the NO ligand can be introduced by
PtBu2)(
m
-H)( -dppm)( -CO)(CO)4] (4) [15] as the main product (see
m
m
hydride abstraction in the dimetal core of [Ru2(m m-H)(m-
-PtBu2)(
Experimental section). In the past, during studies on the reaction
behavior of 3, we found that this compound reacted preferably with
carbon monoxide, which was liberated in side reactions for
example. Thus we found in reaction attempts between 3 and sulfur
dioxide only the product of the CO addition (4) as the main product
dppm)(CO)4] (1, dppm ¼ Ph2PCH2PPh2) by the use of the nitro-
sylating reagent diazald (N-methyl-N-nitroso-p-toluenesulfona-
mide). Thereby the nitrosyl-bridged complex [Ru2(
NO)( -dppm)(CO)4] (2) was obtained in good yield [9]. In this light
we examined now this synthetic pathway for a series of other
dinuclear unsaturated hydrido complexes [Ru2( -H)(
-PtBu2)(
m m-
-PtBu2)(
m
and not the corresponding m-SO2 complex as expected. In contrast
m
m
m-
to this the addition reaction of SO2 was however successful in the
case of the analogous ruthenium complex [6]. During the in-
vestigations described therein we studied in a similar manner the
reaction of 3 with diazald (molar ratio of 1:3) in diethyl ether at
room temperature. In contrast to the studies with the diruthenium
species, we found that the reaction was completed during 5 h
whereas the typical deep green color of the solution (3) was
changed to yellowebrown. After stirring for additional 15 h the
reaction mixture was filtered over alumina. An orangeebrown
band was separated using diethyl ether as the eluent. The investi-
gation of this fraction by 31P{1H} NMR spectroscopy in CD2Cl2
revealed only two products. A minor species (traces) exhibiting
P^P)(CO)4] (P^P ¼ dmpm, 1a; dcypm, 1b; dppen, 1c; dppa, 1d; dpppra,
1e; dpppha, 1f). Thus the latter compounds reacted with an excess
diazald (molar ratio 1:3) in diethyl ether at room temperature
during 48 h resulting in the corresponding nitrosyl-bridged com-
plexes 2aef in good yields (see Scheme 1).
In each case the course of the reaction is accompanied by a color
change from deep violet to green. As described for the parent
complex 1, the preparation of the nitrosyl-bridged species is also
possible in refluxing dioxane as the solvent during shorter reaction
times (2 h) [9]. We found, however, that the reaction at room
three signal groups of an ABX spin system at 309.9 ppm (m, m-
NO
H
PtBu2), 66.1 (m,
m-dppm), and 62.0 (m, m-dppm) with the corre-
+TsN(NO)Me
Ru(CO)2
sponding couplings 2JAx ¼ 31.4, 2JBx ¼ 68.0, and 2JAB ¼ 89.0 Hz was
(CO)2Ru
R2P
Ru(CO)2
PR2
(CO)2Ru
R2P
-TsN(H)Me
Et2O, 48 h
unambiguously assigned to the complex [Fe2(m m-dppm)](m-
-PtBu2)(
P
P
But2
X
But2
CO)(CO)3(NO)] (5). The latter compound was yet described by us
and its molecular structure was confirmed by crystal structure
analysis [18]. This was the only detectable compound containing a
nitrosyl ligand beside the bridging phosphanido group. The second
product (major component, 44% yield) could be unambiguously
PR2
X
2a-f
1a-f
Ts = p-toluenesulfonyl
1a
assigned to [Fe2(m m-H)(m-dppm)(m-CO)(CO)4] (4) by its
-PtBu2)(
1b
R = Me, X = CH2, ; R = Cy, X = CH2,
;
known characteristic NMR data [15]. In the course of these in-
vestigations we were able to obtain orangeebrown crystals of 4
suitable for an X-ray diffraction study and its molecular structure
R = Ph: X = C=CH2, 1c; X = NH, 1d; X = NPrn, 1e; X = NPh, 1f
Scheme 1. Synthesis of nitrosyl-bridged complexes.

T. Mayer et al. / Journal of Organometallic Chemistry 751 (2014) 368e373
371
could be confirmed (see below). At this point some remarks on
possible side reactions should be given. As observed in earlier
studies on reactions of 3 with nitric oxide, we had to ascertain also
in the present case a degradation of the diiron core of 3 during the
reaction resulting in the formation of [Fe(CO)2(NO)2]. This species
was trapped in the vacuum line as a redeorange liquid and char-
acterized by its characteristic IR data. We have to assume that
during this side reaction also carbon monoxide was liberated. To
avoid the addition reaction of the liberated CO towards still un-
consumed compound 3, we carried out the reaction for a short time
in refluxing dioxane with passing a vigorous stream of argon
through the solution. However also in this reaction attempt only
compound 4 (and 5 as a trace) could be detected by NMR
spectroscopy.
3.2. Molecular structures of compounds 2aed and 2f
Compound 2a crystallized from acetone/water in the ortho-
rhombic space group Pnma with four formulas in the unit cell. The
asymmetric unit contained a half molecule of 2a. A selected rep-
resentation of the molecular structure is shown in Fig. 1, selected
bond lengths and angles are summarized in the caption.
Fig. 2. Molecular structure of 2c in the crystal. Thermal ellipsoids were drawn at the
50% probability level. H atoms and thꢁe solvate molecules are omitted for clarity.
Compound 2b crystallized from dichloromethane/ethanol in the
monoclinic space group P21/c with four formulas in the unit cell.
ꢀ
Selected bond lengths (A) and angles ( ): Ru1eRu2, 2.7847(2); Ru1eN, 2.0009(17);
Ru2eN, 2.0070(17); NeO5, 1.221(2), Ru1eC1, 1.892(2); Ru1eC2, 1.917(2); Ru2eC3,
1.914(2); Ru2eC4, 1.896(2); Ru1eP1, 2.3751(6); Ru2eP1, 2.3801(5); Ru1eP2,
2.3493(6); Ru2eP3, 2.3721(6); C5eC6, 1.328(3). Ru1eNeRu2, 88.02(7); Ru1eP1eRu2,
71.69(2); P2eC5eP3, 115.82(11).
The asymmetric unit contained one molecule of [Ru2(
NO)( -dcypm)(CO)4]. Since the features of the molecular structure
m m-
-PtBu2)(
m
of 2b are closely related to that of 2a (except to the substituents on
the bridging bisphosphane ligand) of an ORTEP representation of
the molecule was disclaimed.
molecular structure is shown in Fig. 3, selected bond lengths and
angles are summarized in the caption.
Compound 2f crystallized from acetone/water in the triclinic
space group P 1 with two formulas in the unit cell. The asymmetric
unit contained one molecule of 2f. A selected view of the molecular
Compound 2c crystallized from acetone/water as the acetone
solvate (1.5 acetone) in the monoclinic space group P21/c with four
formulas in the unit cell. The asymmetric unit contained one
molecule of 2c. A selected view of the molecular structure is shown
in Fig. 2, selected bond lengths and angles are given in the caption.
Compound 2d crystallized from acetone/water in the triclinic
space group P 1 with two formulas in the unit cell. The asymmetric
unit contained one molecule of 2d. A selected representation of the
Fig. 3. Molecular structure of 2d in the crystal. Thermal ellipsoids were drawn at the
ꢀ
Fig. 1. Molecular structure of 2a in the crystal. Thermal ellipsoids were drawn at the
50% probability level. H atoms are omittꢁed for clarity. Symmetry operation: ix, ½ ꢀ y, z.
50% probability level. H atoms are omitted for clarity. Selected bond lengths (A) and
angles (ꢁ): Ru1eRu2, 2.7426(7); Ru1eN1, 2.016(4); Ru2eN1, 2.015(4); N1eO5, 1.199(5),
Ru1eC1, 1.898(5); Ru1eC2, 1.928(5); Ru2eC3, 1.913(6); Ru2eC4, 1.896(6); Ru1eP1,
2.4331(13); Ru2eP1, 2.4218(14); Ru1eP2, 2.4134(13); Ru2eP3, 2.4092(13), P2eN2,
1.605(4); P3eN2, 1.607(4). Ru1eN1eRu2, 85.75(15); Ru1eP1eRu2, 68.79(4); P2eN2e
P3, 129.9(3).
i
ꢀ
Selected bond lengths (A) and angles ( ): Ru1eRu1 , 2.7516(6); Ru1eN, 1.999(4); Ne
O3, 1.228(8), Ru1eC1, 1.898(6); Ru1eC2, 1.911(6); Ru1eP1, 2.3913(15); Ru1eP2,
2.3355(14); P2eC3, 1.838(4). Ru1eNeRu1i, 87.0(2); Ru1eP1eRu1i, 70.25(5); P2eC3e
P2i, 116.4(2).

372
T. Mayer et al. / Journal of Organometallic Chemistry 751 (2014) 368e373
be considered as single bonds in each case which is in good
agreement with the observed RueRu distances.
The crystal structure determination on crystals of 4 revealed that
the compound belongs to the triclinic space group P1 with four
crystallographically independent molecules in the asymmetric unit.
A selected view of one molecule of 4 is shown in Fig. 5. Molecules of
compound 4 consist of a diiron core which is bridged by phospha-
nido, dppm, hydrido, and a carbonyl ligand. The coordination sphere
around the two iron atoms is completed by four terminal carbonyl
groups. Thus by electron counting the molecules exhibit 34 valence
electrons and the FeeFe distance can be considered as a single bond.
The structural features of the pair of complexes 3 and 4 are
comparable to the molecular structures of the closely related
compounds [Ru2(
m
-PtBu2)(
-CO)(CO)4] (6) [2]. The metalemetal bond
m-H)(m-dppm)(CO)4] (5) and [Ru2(m-
PtBu2)(
m
-H)( -dppm)(m
m
ꢀ
on going from 5 to 6 is elongated from 2.6974(4) to 2.768(1) A,
ꢀ
whereas the same trend is found on going from 3, 2.496(1) A [2], to
ꢀ
2.5886(9) A in 4. Thus the discussion of MꢀM double bonds in the
unsaturated species [M2(
m
-PtBu2)(
m-H)(CO)4(
m-dppm)] (M ¼ Fe, Ru)
seems to be reasonable.
4. Conclusions
In this paper we described the synthesis and structural char-
acterization of six new dinuclear ruthenium complexes containing
bridging nitrosyl ligands. They were prepared in the reaction of the
Fig. 4. Molecular structure of 2f in the crystal. Thermal ellipsoids were drawn at the
50% probability level. H atoms are omitted for clarity. Selected bond lengths (A) and
ꢀ
angles (ꢁ): Ru1eRu2, 2.7529(4); Ru1eN1, 1.990(2); Ru2eN1, 2.009(3); N1eO5,
1.224(3), Ru1eC1, 1.904(5); Ru1eC2, 1.918(4); Ru2eC3, 1.924(4); Ru2eC4, 1.899(3);
Ru1eP1, 2.3747(9); Ru2eP1, 2.3788(10); Ru1eP2, 2.3431(10); Ru2eP3, 2.3433(10), P2e
N2, 1.738(3); P3eN2, 1.719(3); N2eC5, 1.466(5). Ru1eN1eRu2, 87.01(10); Ru1eP1e
Ru2, 70.78(3); P2eN2eP3, 118.91(16).
coordinatively unsaturated complexes [Ru2(m m-H)(m-
-PtBu2)(
P^P)(CO)4] (P^P ¼ bisphosphanes, N,N-substituted bis(diphenyl-
phosphanyl)amines) with the nitrosylating reagent diazald (N-
methyl-N-nitroso-p-toluenesulfonamide). The hydride abstraction
reactions afforded the corresponding electronically saturated 34 VE
species in good yields under mild conditions. In contrast to this the
reaction principle does not work for the closely related complex
structure is shown in Fig. 4, selected bond lengths and angles are
summarized in the caption.
By electron counting the molecules of compounds 2aed and 2f
exhibit 34 valence electrons and therefore the RueRu contacts can
[Fe2(
was liberated in side reactions, and thus the known compound
[Fe2( -H)( -dppm)( -CO)(CO)4] was obtained as the main
-PtBu2)(
m m-H)(m-dppm)(CO)4]. In this case carbon monoxide
-PtBu2)(
m
m
m
m
product of the reaction. The molecular structure of the latter
complex was confirmed by an X-ray diffraction study.
Acknowledgments
The authors are grateful to the Department of Chemistry of the
Ludwig Maximilian University Munich for supporting these in-
vestigations. T. M. thanks Prof. P. Klüfers for financial support. The
Johnson Matthey Plc, Reading, UK, is grateful acknowledged for a
generous loan of hydrated RuCl3.
Appendix A. Supplementary material
CCDC-941245 (2a), CCDC-941249 (2b), CCDC-941246 (2c),
CCDC-941247 (2d), CCDC-941248 (2f), and CCDC-901382 (4)
contain the supplementary crystallographic data for this paper.
Copies of these data can be obtained from The Cambridge Crys-
tallographic Data Centre via deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk/.
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Fig. 5. Molecular structure of 4 in the crystal. Thermal ellipsoids were drawn at the
50% probability level. H atoms are omitted for clarity (except bridging hydrido ligand).
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