2-(2-pyridyl)-4,6-diphenylphosphinine versus 2-(2-pyridyl)-4,6- diphenylpyridine: Synthesis, characterization, and reactivity of cationic RhIII and IrIII complexes based on aromatic phosphorus heterocycles

Article abstract of DOI:10.1002/chem.201203621

The bidentate P,N hybrid ligand 1 allows access for the first time to novel cationic phosphinine-based Rh^III and Ir^III complexes, broadening significantly the scope of low-coordinate aromatic phosphorus heterocycles for potential applications. The coordination chemistry of 1 towards Rh^III and Ir^III was investigated and compared with the analogous 2,2-bipyridine derivative, 2-(2-pyridyl)-4,6-diphenylpyridine (2), which showed significant differences. The molecular structures of [RhCl(Cp )(1)]Cl and [IrCl(Cp)(1)]Cl (Cp=pentamethylcyclopentadienyl) were determined by means of X-ray diffraction and confirm the mononuclear nature of the λ³-phosphinine-Rh^III and Ir^III complexes. In contrast, a different reactivity and coordination behavior was found for the nitrogen analogue 2, especially towards Rh^III as a bimetallic ion pair [RhCl(Cp)(2)]⁺[RhCl₃(Cp)]^- is formed rather than a mononuclear coordination compound. [RhCl(Cp)(1)]Cl and [IrCl(Cp)(1)]Cl react with water regio- and diastereoselectively at the external Pi?￡C double bond, leading exclusively to the anti-addition products [MCl(Cp)(1H×OH)]Cl as confirmed by X-ray crystal-structure determination. Copyright

Full text of DOI:10.1002/chem.201203621

DOI: 10.1002/chem.201203621
2-(2’-Pyridyl)-4,6-diphenylphosphinine versus 2-(2’-Pyridyl)-4,6-
diphenylpyridine: Synthesis, Characterization, and Reactivity of Cationic
RhIII and IrIII Complexes Based on Aromatic Phosphorus Heterocycles
Iris de Krom,[a] Leen E. E. Broeckx,[a] Martin Lutz,[b] and Christian Mꢀller*[a, c]
Abstract: The bidentate P,N hybrid
ligand 1 allows access for the first time
to novel cationic phosphinine-based
RhIII and IrIII complexes, broadening
significantly the scope of low-coordi-
nate aromatic phosphorus heterocycles
for potential applications. The coordi-
nation chemistry of 1 towards RhIII and
IrIII was investigated and compared
with the analogous 2,2’-bipyridine de-
rivative, 2-(2’-pyridyl)-4,6-diphenylpyri-
dine (2), which showed significant dif-
ferences. The molecular structures of
[RhCl
(Cp*)(1)]Cl and [IrCl
E
analogue 2, especially towards RhIII as
a bimetallic ion pair [RhCl
(Cp*)(2)]+
[RhCl3A
(Cp*)]À is formed rather than a
mononuclear coordination compound.
[RhCl(Cp*)(1)]Cl and [IrCl(Cp*)(1)]Cl
react with water regio- and diastereose-
lectively at the external P=C double
bond, leading exclusively to the anti-
(Cp*=pentamethylcyclopentadienyl)
were determined by means of X-ray
diffraction and confirm the mononu-
clear nature of the l3-phosphinine–
RhIII and IrIII complexes. In contrast, a
different reactivity and coordination
behavior was found for the nitrogen
ACHTUNGTRENNUNG
G
CHTUNGTRENNUNG
G
ACHTUNGTRENNUNG
addition
(1H·OH)]Cl as confirmed by X-ray
crystal-structure determination.
products
[MClACHTUNGTRENNUNG(Cp*)-
AHCTUNGTRENNUNG
Keywords: chelates · coordination
chemistry · heterocycles · N,P li-
gands · phosphorus
Introduction
2,2’-Bipyridine (bpy) and its derivatives are well studied ni-
trogen ligands and their rich coordination chemistry has
often been exploited for the development of molecular devi-
ces, homogeneous catalytic systems or modern materials
with interesting photophysical properties.[1] The replacement
of a pyridine unit by a p-accepting l3-phosphinine entity[2,3]
leads to 2-(2’-pyridyl)phosphinine, a semi-equivalent of bpy
containing a low-coordinate “soft” phosphorus and a “hard”
nitrogen heteroatom. Such chelates are intriguing bidentate
P,N hybrid ligands, which have first been described by
Mathey et al. in 1982 with the synthesis of 2-(2’-pyridyl)-4,5-
dimethylphosphinine (NIPHOS).[4,5]
However, replacing nitrogen by phosphorus in similar
structures causes significant diverse properties due to the
electronic difference that exists between these heteroatoms.
Phosphinines are particularly suitable for the stabilization of
late-transition-metal centers in low oxidation states because
of their pronounced p-accepting character.[3] In contrast, the
preparation of phosphinine complexes containing metal cen-
ters in medium-to-high oxidation states is rather challeng-
ing.[6] Especially for metal centers in higher oxidation states
and with reduced p-back-donation capability, the aromatici-
ty of the phosphinine heterocycle is significantly disrupted
upon coordination. As a result, the phosphinine core be-
haves like a cyclophosphahexatriene containing a highly re-
active P=C double bond. Earlier attempts to prepare such
compounds have shown that they are extremely sensitive to-
wards nucleophilic attack, making their straightforward syn-
thesis, handling, characterization, and potential application
rather unattractive.[7] Yet access to such species would open
up new perspectives in the field of phosphorus-containing
molecular materials, as well as in homogeneous catalysis.
We have recently started to investigate the synthesis and
coordination chemistry of functionalized 2,4,6-triaryl-substi-
tuted phosphinines, which are generally accessible through
[a] I. de Krom, L. E. E. Broeckx, Prof. Dr. C. Mꢀller
Chemical Engineering and Chemistry
Eindhoven University of Technology
Den Dolech 2, 5600 MB Eindhoven (The Netherlands)
[b] Dr. M. Lutz
Bijvoet Center for Biomolecular Research
Crystal and Structural Chemistry, Utrecht University
Padualaan 8, 3584 CH Utrecht (The Netherlands)
[c] Prof. Dr. C. Mꢀller
Institut fꢀr Chemie und Biochemie, Anorganische Chemie
Freie Universitꢁt Berlin, Fabeckstr. 34-36
14195 Berlin (Germany)
Fax : (+49)30-838-52440
E-mail: c.mueller@fu-berlin.de
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201203621.
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Chem. Eur. J. 2013, 19, 3676 – 3684

FULL PAPER
the modular pyrylium-salt route reported by Mꢁrkl and co-
workers.[2a,8–10] It turned out that 2-(2’-pyridyl)-4,6-diphenyl-
phosphinine (1) is readily available from the corresponding
pyridyl-functionalized pyrylium salt.[11] Interestingly, this
route also allowed us to prepare the 2,2’-bipyridine deriva-
tive 2-(2’-pyridyl)-4,6-diphenylpyridine (2) with an identical
substitution pattern, which consequently made for the first
time the direct structural comparison of these heterocycles
and the corresponding transition-metal complexes possi-
ble.[12] We further demonstrated that the neutral complexes
[PdIICl2(1)] and [PtIICl2(1)] could easily be prepared and iso-
cal shift difference upon coordination of DdACHTUNGTRENNUNG
(31P)=
1
À31.0 ppm. The H NMR spectrum shows two sets of dou-
3
4
blet of doublets (3JHÀP =25.1, JHÀP =19.2, JHÀH =1.4 Hz) at
d=8.37 and 8.77 ppm for the two peripheral protons of the
phosphorus heterocycle. From the NMR spectra we con-
clude that quantitative formation of the Rh and Ir com-
plexes 3 and 4 has occurred according to Scheme 1.
lated.[13] Moreover, we also achieved an unprecedented C
À
H activation of 2,4,6-triphenylphosphinine by IrIII and RhIII
precursors.[14] The cyclometalated compounds of type A rep-
resent the first examples of isolated and structurally charac-
terized neutral phosphinine-MIII coordination compounds
reported so far.
Scheme 1. Synthesis of RhIII and IrIII complexes of 1.
Orange crystals of 3 and 4 suitable for X-ray diffraction
were isolated in 91 and 72% yield by slow diffusion of Et2O
into a diluted solution of 1 and [{RhCl
2ACHTUNGTREN(UNGN Cp*)}2] and [{IrCl2-
AHCTUNTGREN(GNUN Cp*)}2] in CH2Cl2, respectively. Complexes 3 and 4 have
the same crystal packing and are thus isomorphous with
very similar unit-cell parameters. They crystallize enantio-
merically purely in the noncentrosymmetric space group
P212121 with one metal complex in the asymmetric unit. Be-
cause both enantiomers were formed during the synthesis, it
can be assumed that crystals of both enantiomers are pres-
ent as a racemic conglomerate. Plots of the molecular struc-
tures in the crystal are given in Figure 1 and selected bond-
ing geometries are compared in Table 1. For a comparison
of bond angles, torsion angles, and interplanar angles in the
molecular structures reported herein, see the Supporting In-
formation.
Both the chelate effect of the bidentate P,N ligand and
the phenyl-group in the 6-position of the heterocyclic frame-
work of 1 are anticipated to contribute significantly to the
formation and stabilization of such complexes. Because the
_
formally anionic ligand (PC) in complex A is isoelectronic
with the neutral P,N ligand 1, we anticipated that cationic
coordination compounds of type B, containing the same
metal fragment should be accessible as well. We report
herein on our first results concerning the synthesis, charac-
terization, and reactivity of such novel cationic phosphi-
nine–MIII (M=Rh, Ir) complexes.
Table 1. Selected distances [ꢃ] and angles [8] in 3 and 4.
Compound
3 (Rh)
1.8078(11)
4 (Ir)
1.819(3)
À
M(1) centroid
À
M(1) Cl(1)
2.3843(7)
2.2659(6)
2.136(2)
1.475(3)
1.720(2)
1.720(2)
1.400(3)
1.406(3)
1.394(3)
1.389(3)
1.347(3)
106.64(12)
77.93(5)
2.3858(19)
2.2428(16)
2.127(6)
1.488(9)
1.717(7)
1.710(6)
1.386(9)
1.405(9)
1.382(9)
1.384(9)
1.364(8)
À
P(1) M(1)
À
N(1) M(1)
À
C(5) C(6)
À
P(1) C(1)
Results and Discussion
À
P(1) C(5)
À
C(1) C(2)
Reaction of 1 with [{RhCl2ACTHNUTRGNE(UNG Cp*)}2] (Cp*=pentamethylcy-
À
C(2) C(3)
À
clopentadiene) in the ratio of 2:1 in CD2Cl2 leads instanta-
neously to a dark-red solution. The 31P{1H} NMR spectrum
of the reaction mixture shows a single doublet at d=
C(3) C(4)
À
C(4) C(5)
À
N(1) C(6)
C(1)-P(1)-C(5)
P(1)-M(1)-N(1)
106.7(3)
78.00(15)
186.0 ppm and a coordination shift of DdACTHUNGTRENNUNG
which is in the expected region for phosphinine–metal com-
plexes with an h1-coordination mode of the phosphorus het-
erocycle. In the 1H NMR spectrum two doublets (3JHÀP
20.8 Hz) at d=8.44 and 8.82 ppm are observed for the two
peripheral protons of the phosphorus heterocycle. Likewise,
reaction of 1 with 0.5 equivalents of [{IrCl2ACTHNUTRGNEU(GN Cp*)}2] in
CD2Cl2 leads exclusively to one single species according to
NMR spectroscopy. The 31P{1H} NMR spectrum of the reac-
tion mixture reveals a signal at d=158.0 ppm and a chemi-
=
The X-ray crystal structures of 3 and 4 in Figure 1 confirm
the observed NMR spectroscopic data and reveal the mono-
nuclear nature of the coordination compounds with the
metal centers displaying the characteristic three-legged
“piano-stool” arrangement. Figure 1 nicely shows the differ-
ence between the aromatic pyridine moiety and the aromat-
ic phosphinine ring, which is best described as a distorted
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3677

C. Mꢀller et al.
served for both free and coordinated phosphinine ligands.
À
The M(1) P(1) bond lengths are 2.2659(6) in
3 and
2.2428(16) ꢃ in 4, and thus are very similar to those in the
_
corresponding neutral complexes [RhCl
N
ACHTUNGTRENUN(NG PC)Cl] and
_
[IrClACTHUNGTREN(NGNU Cp*)ACHTNUGTRENNUNG
ACHTUNGTRENNUNG
[16]
À
À
AHCTUNGTREG(NNNU Cp*)]Cl (Ir(1) N(1)=2.076(8), Ir(1) N(2)=2.090(2) ꢃ).
The bite angles P(1)-M(1)-N(1) are very similar for the two
coordination compounds with 77.93(5) (3) and 78.00(15)8
(4) and slightly larger than in [IrACTHNUGTRNENUG(bpy)ClACHTUNGTNER(NUGN Cp*)]Cl (76.2(3)8)
due to the presence of two different heteroatoms. Most
strikingly, the metal centers are not located in the ideal axis
of the phosphorus lone pair but clearly shifted towards the
nitrogen atom (C(5)-P(1)-Rh(1)=108.23(9), C(1)-P(1)-
Rh(1)=145.10(8), C(5)-P(1)-Ir(1)=108.8(2), C(1)-P(1)-
Ir(1)=144.4(2)8). Clearly, this effect is necessary for an effi-
cient complexation of the metal atom by the chelating P,N
ligand and facilitated by the more diffuse and less direction-
al lone pair of the low-coordinate phosphorus atom relative
to the sp2-hybridized nitrogen atom in pyridines. Conse-
quently, it is not observed for the M(1)–N(1) interactions
(C(6)-N(1)-Rh(1)=123.41(15),
C(10)-N(1)-Rh(1)=
117.17(16), C(6)-N(1)-Ir(1)=123.6(4), C(10)-N(1)-Ir(1)=
117.7(5)8). As observed by us before, the phenyl substituents
in the a-position of the P-heterocycle are shifted away from
the coordination site and are additionally rotated out of the
plane of the P-heterocycle (torsion angles P(1)-C(1)-C(11)-
C(12)=42.8(3)8 (3) and À43.3(9)8 (4)). In this way, the P-li-
gating ability of such 2,4,6-triaryl-substituted phosphinines is
À
apparently not influenced as dramatically as observed for
SiMe3-substituted ones, which show a preference for h6-coor-
dination through the aromatic ring, rather than for h1-coor-
dination through the phosphorus lone pair.[17]
Complexes 3 and 4 are the first reported crystallographic
characterizations of cationic phosphinine–RhIII and IrIII com-
plexes. To form a strong bond with a Lewis acidic metal
center the lone pair at the phosphorus atom, containing a
high s character in the free ligand, must gain considerable p
character upon coordination. This leads to an opening of the
internal aC-P-C angle, which is approximately 1008 in a
free phosphinine. Because this phenomenon can thus be cor-
related with the electron-accepting character of a metal-
fragment, it appears interesting to compare the aC-P-C
angles in 3 and 4 with selected literature data.[18] In the Cr0
Figure 1. Molecular structures of 3 (top) and 4 (bottom) in the crystal.
Displacement ellipsoids are shown at the 50% probability level. Only
one enantiomer is shown. The absolute structure of 3 has been inverted
in the drawing with respect to the X-ray crystal structure for reasons of
clarity.
complex [Cr(CO)4ACTHNUTRGNEUNG(tmbp)] (tmbp=tetramethylbisphosphi-
nine),[19] the aC-P-C angle is 104.38. As a matter of fact,
À
hexagon due to the larger P C bond length in comparison
this compound is highly stable towards nucleophilic attack.
to the N C bond length. The two heterocyclic rings in 3 and
In the RhI complex [Rh
G
ACHTUNGRTEN[NUNG BF4] (cod=1,5-cycloocta-
À
4 are essentially coplanar with respect to one another with
À
an intercyclic C C bond length of 1.475(3) in 3 and
N
ACHTUNGTRENNUNG
À
À
1.488(9) ꢃ in 4. The P C(1) and P C(5) bond lengths of
1.720(2)/1.710(2) (3) and 1.717(7)/1.710(6) ꢃ (4) are some-
what shorter than in free 2,4,6-triarylphosphinines (1.74–
1.76 ꢃ),[15] whereas the carbon–carbon bond lengths in the
aromatic phosphinine subunit are in the usual range
(1.389(3)–1.406(3) in 3 and 1.382(9)–1.405(9) ꢃ in 4) ob-
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Cationic RhIII and IrIII Complexes
FULL PAPER
of the aromaticity and consequently a high reactivity of the
P=C double bond is expected (see below), both compounds
can easily be isolated, handled, and characterized and seem
to be considerably more stable than, for example, the
NIPHOS-containing cationic PdII and PtII complexes descri-
bed by Venanzi et al.[7,18] As mentioned above, we assume
that the additional aryl substituents at the 2- and 6-positions
of the heterocyclic framework might indeed contribute to a
steric protection of the P=C double bond as we have ob-
served before for neutral [PdCl2(1)] and [PtCl2(1)] com-
plexes, as well as for the neutral phosphinine–RhIII and IrIII
_
complexes [MClACHTUNGTRENNUNG(Cp*)ACHTUTGNREN(NUGN PC)], containing a cyclometalated
2,4,6-triphenylphosphinine ligand.
To compare the coordination behavior of 1 with the anal-
ogous 2,2’-bipyridine derivative 2, we reacted ligand 2 with
[{RhCl2ACHTUNGTRENNUNG(Cp*)}2] in a ratio of 2:1 in CD2Cl2 under identical
1
conditions to those described above. In the H NMR spec-
trum of the reaction mixture the immediate formation of a
new species was observed, which shows two different Cp*
units. Moreover, one equivalent of unreacted ligand 2 was
still present in solution and this ratio did not change upon
heating the reaction mixture either. However, in the case of
reacting 2 with [{IrCl2ACHTNUGTRNE(UGN Cp*)}2] in a ratio of 2:1 in CD2Cl2,
the formation of only one single species was observed by
1H NMR spectroscopy. Based on the NMR spectra we,
therefore, propose the formation of the bimetallic ion pair
[RhClACHTUNGTRENNUNG(Cp*)(2)] CHTUNGTRENNUNG[RhCl3ACHTNUGTRENNUGN
+A (Cp*)]À (5), whereas a monomeric
species is expected for compound 6 (Scheme 2).
By slow diffusion of Et2O into a diluted solution of 5 and
6 in CD2Cl2, yellow and orange crystals, respectively, suita-
ble for X-ray diffraction were isolated in 82 (based on Rh)
and 89% yield. Compound 5 crystallizes enantiopurely in
the orthorhombic space group P212121 and the asymmetric
unit consists of one metal complex molecule. The Ir complex
6 crystallizes as a racemate in the monoclinic space group
P21/n with one metal complex molecule in the asymmetric
unit. Plots of the molecular structures of one enantiomer in
Figure 2. Molecular structures of 5 (top) and 6 (bottom) in the crystal.
Displacement ellipsoids are shown at the 50% probability level. In the
drawing of 6, the asymmetric unit chosen is different from that in the
Supporting Information for reasons of clarity.
the crystal are given in Figure 2
and selected bonding geome-
tries are compared in Table 2.
Indeed, the molecular struc-
ture of 5 in the crystal reveals
the presence of the bimetallic
ion
[RhCl
pair
[RhClACHNUTGTRENNUNG
N
N
6
present as a monomeric species,
as observed in solution. It ap-
pears that complete dissociation
of the metal precursor dimer,
[{RhCl2ACHTNUGTRNEUNG(Cp*)}2], to form mono-
meric species cannot be ach-
ieved by the bidentate bipyri-
dine derivative. This has been
observed before for related sp2-
N donor ligands, although the
Scheme 2. Synthesis of RhIII and IrIII complexes of 2.
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3679

C. Mꢀller et al.
Table 2. Selected distances [ꢃ] and angles [8] in 5 and 6.
tion between the a-phenyl group and the remaining ligands
around the metal center might consequently cause a distor-
Compound
5 (Rh)
6 (Ir)
tion, which is essentially absent in [Ir
though it has been observed before in the complex [Rh-
(cod)(2)]
[BF4].[12a]
Despite the fact that the additional aryl substituents at
ACHUTGTNREN(UNG bpy)ClAHCTUNGTREN(NGUN Cp*)]Cl, al-
À
M(1) centroid
1.7862(18)
1.7578(18)
2.4003(11)
2.178(3)
2.071(3)
1.491(6)
1.360(5)
1.366(5)
1.341(5)
1.342(5)
1.794
–
À
M(2) centroid
À
M(1) Cl(1)
2.4110(4)
2.1447(14)
2.0784(14)
1.471(2)
1.362(2)
1.371(2)
1.352(2)
1.342(2)
76.39(5)
G
ACHTUNGTRENNUNG
À
N(1) M(1)
À
N(2) M(1)
the 2- and 6-positions of the heterocyclic framework contrib-
ute significantly to a kinetic stabilization of the metal com-
plexes 3 and 4 as they can easily be isolated, handled, and
characterized, the larger opening of the aC-P-C angle in
comparison to a free phosphinine reflects significant disrup-
tion of the aromaticity.[18] Consequently, a considerable reac-
tivity of the P=C double bond in 3 and 4 towards H2O is
still anticipated as observed before by us for neutral and cat-
ionic PdII and PtII complexes as well. As a matter of fact,
adding a drop of H2O to a solution of 3 and 4 in CD2Cl2
leads to quantitative formation of the new species 7 and 8
and is accompanied by a color change from orange to
yellow.
À
C(5) C(6)
À
N(1) C(1)
À
N(1) (C5)
À
N(2) C(6)
À
N(2) C(10)
N(1)-M(1)-N(2)
76.47(13)
different behavior of the Rh and Ir dimer is not clear at the
moment.[21] Nevertheless, a clear difference concerning the
reactivity and coordination behavior between the two ligand
systems 1 and 2 is apparent.
In contrast to coordination compounds 3 and 4, contain-
ing the P,N hybrid ligand, the molecular structure of the bi-
pyridine-based complex 5 reveals a strong distortion, as the
two pyridine rings are notably twisted (torsion angle N1-C5-
C6-N2=À15.9(5)8, interplanar angle between the least-
square planes=19.97(18)8). In contrast, the two pyridine
rings are essentially coplanar in complex 6, but bent towards
one another (torsion angle N1-C5-C6-N2=1.6(2)8, interpla-
nar angle between the least-square planes=13.54(8)8). The
The addition of H2O and alcohols to NIPHOS-containing
cationic complexes [PtCl(L)
(NIPHOS)]+ under formation of [PtCl(L)(NIPHOSH·-
(NIPHOS)]+ and [PdCl(L)-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
OH)]+ and [PdCl(L)(NIPHOSH·OH)]+ has been described
by Venanzi et al. before.[7] In contrast to these compounds,
the addition of H2O to the external P=C double bond of the
chiral complexes 3 and 4 would lead principally to a mixture
of diastereomers because not only a stereogenic Ca atom is
generated due to the additional phenyl group at the 6-posi-
tion of the heterocycle, but also to a stereogenic phosphorus
atom. The addition of the H2O molecule could occur in a
syn or anti fashion and, furthermore, also through the Re or
the Si site of the P=C double bond (Scheme 3).
À
intercyclic C(5) C(6) bond length is 1.491(6) in 5 and
1.471(2) ꢃ in 6. Thus, in 5, it is identical to that in the free
2,2’-bipyridine (1.490(3) ꢃ)[22], and slightly shorter in 6. The
À
N(1) C(5) bonds are 1.366(5) (5) and 1.371(2) ꢃ (6), that is,
slightly longer than the corresponding bond in 2,2’-bipyri-
dine (1.346(2) ꢃ). The bite
angles N(1)-M(1)-N(2) are
76.47(13) in 5 and 76.39(5)8 in
6. The iridium compound 6 can
be compared with the crystallo-
graphic data of [IrACTHUNGTRENN(UNG bpy)Cl-
ACHTUNGTRENNUNG(Cp*)]Cl. In the latter complex,
À
the mean Ir Cp* distance is
À
1.786 ꢃ, whereas the N(1)
À
Ir(1) and N(2) Ir(1) distances
are very similar to
6 with
2.076(8) and 2.090(9) ꢃ, respec-
Scheme 3. Reaction of 3 and 4 with H2O.
À
tively. The C(5) C(6) bond
length in [Ir
G
A
1.49(1) ꢃ and thus slightly longer than in 6, while the bite
angles N(1)-Ir-N(2) are equal within standard deviations. In
contrast to compound 6, the two pyridine rings in [Ir-
The 31P{1H} NMR spectra of [RhCl
and [IrCl(Cp*)(1H·OH)]Cl (8) show, however, only a single
ACHUTGTNREN(UNG Cp*)CAHUTNGTREN(NNGU 1H·OH)]Cl (7)
G
ACHTUNGTRENNUNG
resonance at d=86.0 and 58.0 ppm, respectively (CD2Cl2).
This excludes the formation of diastereomeric product mix-
tures generated by either a random addition of the H2O
molecule to the Re or Si site of the P=C double bond or a
random transfer of the proton to the Ca atom. Accordingly,
ACHTUNGTRENNUNG(bpy)ClACHTUNGTRENNUNG(Cp*)]Cl are perfectly coplanar and only slightly
bent towards one another. It appears that ligand 2 does not
behave like a typical 2,2’-bipyridine ligand. The observed
differences in the coordination geometries are most likely
due to the fact that the additional phenyl substituent at the
a-position of the N(1)-pyridine ring of 2 is much closer to
the coordination site relative to the situation in the corre-
sponding pyridine–phosphinine ligand 1. The steric interac-
1
the H NMR spectra of 7 and 8 show only one set of signals,
with characteristic resonances for the protons Ha and Hb at
3
2
d=4.78 (dd, JHÀH =2.8, JHÀP =12.0 Hz) and 6.53 ppm (dd,
3JHÀH =2.4, 3JHÀP =8.0 Hz; 7), as well as at d=4.61 (dd,
3680
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ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 3676 – 3684

Cationic RhIII and IrIII Complexes
FULL PAPER
À
structure, which shows the expected values of C(2)
À
À
C(3)=1.350(5), C(3) C(4)=1.464(4), and C(4) C(5)=
À
1.351(4) ꢃ. In compound 8, values of C(1) C(2)=
1.505(3), C(2) C(3)=1.340(3), C(3) C(4)=1.471(3),
and C(4) C(5)=1.344(3) ꢃ were found. The bite angles
N(1)-M(1)-P(1) are 82.27(7)8 in 7 and 80.22(6) in 8, and
thus are larger than in the starting materials 3 and 4.
Interestingly and in contrast to the anti addition of
H2O to the P=C double bond in 3 and 4, we have recent-
ly observed that the reaction of the neutral complexes
À
À
À
Figure 3. 1H NMR spectra (CD2C2, 400 MHz) of 4 and 8. Hp/p’ =peripher-
3
al H atoms at the P heterocycle with J(H,P) coupling.
3
3JHÀH =2.8, 2JHÀP =12.4 Hz) and 6.66 ppm (brd, JHÀP
=
1
9.6 Hz) for species 8. Figure 3 illustrates the H NMR spec-
tra of the Ir complex 4 (Hp =peripheral hydrogen atoms of
the heterocycle) and of the product 8 after the addition of
H2O. As expected, the bipyridine-containing complexes 5
and 6 do not show any reactivity towards H2O under the
same conditions as described for 3 and 4, although Gillard
et al. have found that [PtACHTNUTRGNE(NUG bpy)(CN)2] also adds H2O regiose-
lectively, whereas the OH group adds to the Ca-atom due to
the different charge distribution in pyridine and phosphi-
nine.[23]
From these observations, we can conclude that the addi-
tion of H2O to the external P=C double bond proceeds dia-
stereoselectively and not randomly. Interestingly, due to the
phenyl substituent at the 6-position of the P-heterocycle, an
investigation of 7 and 8 by means of X-ray crystal-structure
determinations would allow the differentiation between
anti- and syn-addition, as well as between addition through
the Re or Si site of the P=C double bond. Crystals of 7 and
8 suitable for X-ray diffraction were obtained in 85 and
96% isolated yield, respectively, by slow diffusion of Et2O
into a diluted solution of 7 and 8 in CD2Cl2. The compounds
crystallize as racemates in the orthorhombic space group
¯
Pbca (7) and in the triclinic space group P1 (8) with one
metal complex molecule in the asymmetric unit. The molec-
ular structures of one enantiomer each are depicted in
Figure 4 and selected bonding geometries are compared in
Table 3.
The molecular structures of 7 and 8 in the crystal unam-
biguously show that the H2O molecule has been added in an
anti fashion to the P(1)=C(1) double bond, rather than in a
syn fashion. Moreover, the H2O molecule has been added
selectively to only one side of the heterocycle in such a way
that the OH group is pointing away from the Cl ligand. Ad-
ditionally, hydrogen bonding between the OH group and
the Cl counteranion occurs. The phosphorus atom shows a
Figure 4. Molecular structures of 7 (top, two CH2Cl2 solvent molecules
are omitted for clarity) and 8 (bottom) in the crystal. Displacement ellip-
soids are shown at the 50% probability level. In the drawing of 8, the
asymmetric unit chosen is different from that in the Supporting Informa-
tion for reasons of clarity.
À
distorted tetrahedral structure with a P(1) C(1) bond length
of 1.836(3) ꢃ and a P(1)–C(5) distance of 1.811(3) in 7 and
of 1.827(2) and 1.803(2) ꢃ, respectively, in 8, reflecting the
sp3 hybridization of C(1) and the sp2 hybridization of C(5).
À
Moreover, the C(1) C(2) bond in 7 corresponds to a single
[PdCl2(1)] and [PtCl2(1)] with methanol leads quantitatively
and selectively to a syn addition of CH3OH to the external
P=C double bonds as demonstrated by single-crystal X-ray
À
bond (1.508(4) ꢃ), whereas the remaining C C bond lengths
in the phosphorus heterocycle are in agreement with a diene
Chem. Eur. J. 2013, 19, 3676 – 3684
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
3681

C. Mꢀller et al.
Table 3. Selected distances [ꢃ] and angles [8] in 7 and 8.
significant differences in the coordination behavior of the
P,N ligand towards RhIII and IrIII were observed, compared
to the structurally related N,N ligand (2). The N,N ligand
not only causes a distortion of the corresponding RhIII and
IrIII complex, due to steric interactions between the ligand
Compound
7 (Rh)
8 (Ir)
À
M(1) centroid
1.8324(14)
2.4012(8)
2.2552(8)
2.116(3)
1.468(4)
1.836(3)
1.811(3)
1.508(4)
1.350(5)
1.464(4)
1.351(4)
1.354(4)
1.578(2)
98.52(14)
82.27(7)
1.8453(12)
2.3972(6)
2.2548(6)
2.1284(19)
1.467(3)
1.827(2)
1.803(2)
1.505(3)
1.340(3)
1.471(3)
1.344(3)
1.362(3)
1.5745(18)
98.74(11)
80.22(6)
À
M(1) Cl(1)
À
P(1) M(1)
À
N(1) M(1)
framework and the coordinated {MCl
also leads to the formation of the bimetallic ion pair [RhCl-
(Cp*)(2)] [RhCl3A
+A (Cp*)]À. This repulsion is much less pro-
ACHTUNGTREN(NUGN Cp*)} fragment but
À
C(5) C(6)
À
P(1) C(1)
A
N
CHTUNGTRENNUNG
À
P(1) C(5)
À
C(1) C(2)
nounced in the related phosphinine–pyridine ligand, mainly
as a result of the larger phosphorus atom. The reaction with
water leads quantitatively and regio- and diastereoselective-
ly to an anti addition of H2O to the external P=C double
bonds as unambiguously demonstrated by X-ray crystal-
À
C(2) C(3)
À
C(3) C(4)
À
C(4) C(5)
À
N(1) C(6)
À
P(1) O(1)
C(1)-P(1)-C(5)
P(1)-M(1)-N(1)
structure determination of the products [MCl
ACHTUNGTRENNUNG(Cp*)-
AHCTUNGTREG(NNNU 1H·OH)]Cl (M=Rh, Ir). The results described herein dem-
onstrate that the bidentate P,N hybrid ligand, 2-(2’-pyridyl)-
4,6-diphenylphosphinine (1), allows for access for the first
time to novel cationic RhIII and IrIII complexes, broadening
significantly the scope of low-coordinate aromatic phospho-
rus heterocycles for potential applications.
diffraction of the product [PdCl2ACHTNUTRGNEUNG(1H·OCH3)] (Figure 5). The
regioselective addition of methanol exclusively to the P(1)=
C(1) double bond was attributed to the somewhat higher
nucleophilicity of C(1) due to the electron-withdrawing
character of the pyridine ring connected to C(5), leading to
a preferred addition of a proton to C(1). However, the
cause of the difference in anti and syn addition between
these two systems remains speculative at the moment and
needs further investigations.
Experimental Section
General remarks: All reactions were performed under argon by using
Schlenk techniques or in an MBraun dry box unless stated otherwise. All
glassware was dried prior to use. All common solvents and chemicals
were commercially available. [IrCl2ACHTNUGTRENN(GU Cp*)]2 and [RhCl2ACHTUGNTREN(NUGN Cp*)]2 were pur-
chased from STREM and used without further purification. 2-(2’-Pyrid-
yl)-4,6-diphenylphosphinine (1) and 2-(2’-pyridyl)-4,6-diphenylpyridine
(2) were prepared according to literature procedures.[11,12a] The dry sol-
vents were prepared by using custom-made solvent purification columns
filled with Al2O3. Elemental analyses were performed by H. Kolbe, Mik-
roanalytisches Laboratorium, Mꢀlheim a. d. Ruhr (Germany). 1H,
13C{1H}, and 31P{1H} NMR spectra were recorded on a Varian Mercury
200 or 400 MHz spectrometer and all chemical shifts are reported rela-
tive to residual proton resonance of the deuterated solvents.
AHCTUNGRTENGNU[N RhClACHTUNRTGEN(GNUN Cp*)(1)]Cl (3): A mixture of [RhCl2ACHTNUGTNER(NGUN Cp*)]2 (19 mg, 0.03 mmol,
1.0 equiv) and 1 (20 mg, 0.06 mmol, 2.0 equiv) was suspended in CD2Cl2
(0.5 mL) and transferred to a Young NMR-Tube in a dry box. The reac-
tion was completed after 4 h at room temperature. Crystals were ob-
tained by slow diffusion of diethyl ether into the reaction mixture. Yield:
91% (after crystallization); 1H NMR (CD2Cl2, 400 MHz): d=1.58 (15H,
d, 3J(H,H) =5.6 Hz; Me from Cp*), 7.48–7.63 (6H, m; Harom), 7.70 (1H, t,
3J=6.6 Hz; Harom), 7.77 (2H, d, 3J(H,H) =7.6 Hz; Harom), 7.82 (2H, d,
3J(H,H) =7.2 Hz; Harom), 8.23 (1H, t, 3J=8.0 Hz; Harom), 8.44 (1H, d,
3J(P,H) =20.8 Hz; Hp), 8.54 (1H, d, 3J(H,H) =4.0 Hz; Harom), 8.82 (1H, d,
3J(P,H) =20.8 Hz; Hp’), 8.83 ppm (1H, s; Harom); 31P NMR (CD2Cl2,
162 MHz): d=186.0 ppm (d, 1J(Rh,P) =130 Hz); 13C NMR (CD2Cl2
100.63 MHz): d=10.0 (CH3 from Cp*), 103.7 (Cq from Cp*), 122.1 (CH),
122.2 (CH), 127.5 (CH), 128.1 (CH), 128.2 (d, 4J(C,P) =3.2 Hz; CH), 128.6
(d, 2J(C,P) =11.5 Hz; CH), 129.3 (CH), 129.4 (CH), 129.7 (CH), 130.3
(CH), 130.5 (CH), 133.2 (2J(C,P) =14.7 Hz, CH), 138.4 (Cq), 138.5 (Cq),
Figure 5. Water and methanol addition products of metal complexes con-
taining ligand 1.
Conclusion
We have demonstrated for the first time that the cationic
mononuclear complexes [MClACTHNUTRGNEUGN(Cp*)(1)]Cl (M=Rh, Ir) con-
taining the chelating P,N hybrid ligand 2-(2’-pyridyl)phosphi-
nine (1) can easily be prepared and isolated by starting from
the corresponding [MCl2ACTHNUTRGNE(NUG Cp*)]2 metal precursors. The mo-
lecular structures of both compounds were determined by
means of X-ray crystallography and represent the first struc-
turally characterized cationic l3-phosphinine complexes of
RhIII and IrIII. Both the chelate effect of the bidentate ligand
and the aryl groups at the 2- and 6-positions of the heterocy-
clic framework are anticipated to contribute significantly to
the formation and stabilization of such complexes. Due to
the presence of electronically and sterically rather different
phosphorus and nitrogen centers within the same structure,
2
139.8 (d, J(C,P) 14.6 Hz; CH), 140.5 (Cq), 140.6 (Cq) 141.1 (CH), 143.5
(Cq), 155.9 (CH), 157.5 ppm (Cq); elemental analysis calcd (%) for
C32H31NPCl2Rh·0.5CH2Cl2 (676.89 gmolÀ1): C 57.67, H 4.76%, N 2.07;
found: C 57.60, H 4.68, N 2.20.
AHCTUNGRTENGNN[U IrClAHCTUNGERT(NGNUN Cp*)(1)]Cl (4): A mixture of [IrCl2ACHUTGTNRNENUG(Cp*)]2 (24 mg, 0.03 mmol,
1.0 equiv) and 1 (20 mg, 0.06 mmol, 2.0 equiv) was suspended in CD2Cl2
(0.5 mL) and transferred to a Young NMR-Tube in a dry box. The reac-
tion was completed after 1 h at room temperature. Crystals were ob-
tained by slow diffusion of diethyl ether into the reaction mixture. Yield:
72% (after crystallization); 1H NMR (CD2Cl2, 400 MHz): d=1.62 (15H,
3682
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ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 3676 – 3684

Cationic RhIII and IrIII Complexes
FULL PAPER
d, 4J(H,P) =3.6 Hz; Me), 7.47 (1H, m; Harom), 7.53–7.66 (6H, m; Harom),
ACHTUNGTRENU[NGN IrClACHNUTRTGEG(NNUN Cp*)ACHTNUGTRNE(NUGN 1H·OH)]Cl (8): Compound 4 (22 mg, 0.03 mmol, 1.0 equiv)
3
was suspended in CD2Cl2 (0.5 mL) and transferred to a Young NMR-
Tube under argon. An excess of water (22 mg, 1.20 mmol, 40.0 equiv) was
added to the mixture and 8 was formed instantaneously. Crystals were
obtained by slow diffusion of diethyl ether into the reaction mixture.
Yield: 96% (after crystallization); 1H NMR (CD2Cl2, 400 MHz): d=1.42
(15H, s; Cp* CH3), 4.61 (1H, dd, 2J(H,P) =12.4, 3J(H,H) =2.8 Hz; Ha), 6.66
(1H, brd, 3J(H,P) =9.6 Hz; Hb), 7.19 (1H, s; Harom), 7.28 (3H, m; Harom),
7.38 (5H, m; Harom), 7.45 (1H, s; Harom), 7.66 (2H, m; Harom), 7.99 (1H, t,
3J=7.4 Hz; Harom), 8.12 (1H, d, 3J(H,P) =6.8 Hz; Harom), 8.55 ppm (1H, d,
3J(H,H) =5.6 Hz; Harom); 31P NMR (CD2Cl2, 162 MHz): d=58.0 ppm;
13C NMR (CD2Cl2, 100.37 MHz): d=8.8 (CH3 from Cp*), 47.1 (CH), 47.5
(CH), 95.8 (Cq from Cp*), 121.4 (d, 3J(C,P) =7.6 Hz; CH), 126.0 (CH),
7.75–7.79 (4H, m; Harom), 8.17–8.20 (1H, m; Harom), 8.37 (1H, dd, J(H,P)
=
25.1, 4J(H,H) =1.4 Hz; Hp), 8.62 (1H, d, 3J(H,H) =8.4 Hz; Harom), 8.77 (1H,
dd, 3J(H,P) =19.2, 4J(H,H) =1.4 Hz; Hp’), 8.78 ppm (1H, d, 3J(H,H) =5.6 Hz;
H
arom); 31P NMR (CD2Cl2, 162 MHz): d=158.0 ppm; 13C NMR (CD2Cl2
100.63 MHz): d=9.3 (C5Me5), 97.3 (d, 4J(C,P) =2.6 Hz; C5Me5), 121.5,
121.6, 127.27, 127.30, 127.9, 128.0, 128.6, 128.7, 128.9, 129.5, 130.1, 133.5
(d, 2J(C,P) =13.3 Hz), 138.1 (d, 2J(C,P) =12.5 Hz), 140.3 (d, 2J(C,P) =11.4 Hz),
140.5 (d, 3J(C,P) =5.5 Hz), 141.2, 141.4, 149.9 (d, 1J(C,P) =40.7 Hz), 150.6 (d,
1J(C,P) =37.4 Hz; Ca), 156.7, 158.7 ppm (d, 2J(C,P) =16.1 Hz); elemental
analysis calcd (%) for C32H31NPCl2Ir·0.5CH2Cl2 (766.20 gmolÀ1): C 50.95,
H 4.21, N 1.83; found: C 51.02, H 4.25, N 2.05.
ACHTUNGTRENNUNG[RhClACHTUNGTRENNUNG(Cp*)(2)]ACHTUNGTRENNUNG[RhCl3ACHTUNGTRENNUNG(Cp*)] (5): A mixture of [RhCl2ACHTUNGTERNUGN(Cp*)]2 (20 mg,
127.3 (CH), 128.1 (d, 4J(C,P) =3.0 Hz; CH), 128.2 (CH), 128.8 (CH), 129.0
0.033 mmol, 1.0 equiv) and 2 (20 mg, 0.065 mmol, 2.0 equiv) was suspend-
ed in CD2Cl2 (0.5 mL) and transferred to a Young NMR-Tube in a dry
box. The reaction was completed after 1 h at room temperature. Crystals
were obtained by slow diffusion of diethyl ether into the reaction mix-
ture. Yield: 82% (after crystallization, based on Rh); 1H NMR (CD2Cl2,
2
(d, 4J(C,P) =2.5 Hz; CH), 130.8 (d, 3J(C,P) =5.3 Hz; CH), 138.1 (d, J(C,P)
=
11.4 Hz; Cq), 139.3 (CH), 140.8 (d, 3J(C,P) =2.5 Hz; Cq), 155.6 (CH), 159.8
(d, 2J(C,P) =18.1 Hz; Cq); elemental analysis calcd (%) for
C32H33NPOCl2Ir·0.5CH2Cl2 (741.13 gmolÀ1): C 49.81, H 4.37, N 1.79;
found: C 49.01, H 4.58, N 1.67.
400 MHz): 1.16 (15H, s; Me from Cp*), 1.54 (15H, s; Me from Cp*),
2
7.61 (6H, m; Harom), 7.81 (1H, t, 3J=6.2 Hz; Harom), 7.94 (2H, d, J(H,H)
=
7.2 Hz; Harom), 8.12 (1H, s; Harom), 8.26 (1H, t, 3J=7.8 Hz; Harom), 8.42
(2H, s; Harom), 8.49 (1H, d, 2J(H,H) =8.4 Hz; Harom), 8.59 (1H, s; Harom),
8.81 ppm (1H, d, J(H,H) =8.2 Hz; Harom); 13C NMR (CD2Cl2 100.37 MHz):
3
Acknowledgements
d=8.8 (CH3 from C5Me5), 9.4 (CH3 from C5Me5), 97.3 (Cq, C5Me5), 97.4
(Cq, C5Me5), 120.9 (CH), 126.0 (CH), 127.1 (CH), 127.3 (CH), 127.5
(CH), 128.1 (CH), 128.4 (CH), 129.0 (CH), 129.3 (CH), 129.4 (CH),
129.9 (CH), 131.1 (CH), 131.35 (CH), 131.43 (CH), 135.2 (Cq), 139.5
(Cq), 141.7 (CH), 152.2 (CH), 152.7 (Cq), 155.7 (Cq), 157.2 (Cq),
This research has been funded by The Netherlands Organization for Sci-
entific Research (NWO-Vidi and NWO-ECHO grant for C.M.). The
COST-Action PhoSciNet (CM0802) is gratefully acknowledged.
164.7 ppm
(Cq);
elemental
analysis
calcd
41.76,
(%)
4.18,
for
1.04;
C42H46N2Cl4Rh2·5CH2Cl2 (1351.56 gmolÀ1):
C
H
N
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found: C 42.26, H 4.78, N 1.19.
ACHTUNGTRENNUNG[IrClACHTUNGTRENNUNG(Cp*)(2)]Cl (6): A mixture of [IrCl2ACHTNUGTNER(NGUN Cp*)]2 (26 mg, 0.033 mmol,
1.0 equiv) and 2 (20 mg, 0.065 mmol, 2.0 equiv) was suspended in CD2Cl2
(0.5 mL) and transferred to a Young NMR-Tube in a dry box. The reac-
tion was completed after 4 h at room temperature. Crystals were ob-
tained by slow diffusion of diethyl ether into the reaction mixture. Yield:
89% (after crystallization). 1H NMR (CD2Cl2, 400 MHz): d=1.15 (15H,
s; Me), 7.59 (6H, m; Harom), 7.80 (1H, t, 3J=6.6 Hz; Harom), 7.84 (2H, d,
2J(H,H) =6.8 Hz; Harom), 8.07 (1H, s; Harom), 8.24 (1H, t, J=7.4 Hz; Harom),
3
8.36 (2H, s; Harom), 8.60 (1H, d, 2J(H,H) =7.6 Hz; Harom), 8.63 (1H, d,
4J(H,H) =2.0 Hz; Harom), 8.76 ppm (1H, d, J(H,H) =5.6 Hz; Harom); 13C NMR
2
(CD2Cl2 100.37 MHz): d=8.5 (CH3 from C5Me5), 89.6 (Cq, C5Me5), 120.9
(CH), 126.1 (CH), 127.9 (CH), 128.2 (CH), 128.7 (CH), 129.2 (CH),
129.8 (CH), 130.9 (CH), 131.5 (CH), 131.8 (CH), 134.8 (Cq), 140.1 (Cq),
141.7 (CH), 151.6 (CH), 152.4 (Cq), 156.5 (Cq), 158.2 (Cq), 164.7 ppm
(Cq); elemental analysis calcd (%) for C32H31N2Cl2Ir·CH2Cl2
(791.72 gmolÀ1): C 50.06, H 4.20, N 3.55; found: C 50.69, H 4.49, N 3.81.
ACHTUNGTRENNUNG[RhClACHTUNGTRENNUNG(Cp*)ACHTUNGTRENNUNG(1H·OH)]Cl (7): Compound 3 (19 mg, 0.03 mmol, 1.0 equiv)
was suspended in CD2Cl2 (0.5 mL) and transferred to a Young NMR-
Tube under argon. An excess of water (22 mg, 1.20 mmol, 40.0 equiv) was
added to the mixture and 7 was formed instantaneously. Crystals were
obtained by slow diffusion of diethyl ether into the reaction mixture.
Yield: 85% (after crystallization). 1H NMR (CD2Cl2, 400 MHz): d=1.30
(15H, d, 4J(H,P) =3.2 Hz; CH3 from Cp*), 4.78 (1H, dd, 2J(H,P) =12.0,
3J(H,H) =2.8 Hz; Ha), 6.53 (1H, dd, 3J(H,P) =8.0, 3J(H,H) =2.4 Hz; Hb), 7.06
(2H, s; Harom), 7.22 (3H, m; Harom), 7.32 (1H, d, 3J(H,P) =17.6 Hz; Harom),
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3
2
7.38 (4H, m; Harom), 7.66 (2H, dd, J(H,H) =4.0, J(H,H) =1.8 Hz; Harom), 8.03
(1H, t, 3J=7.6 Hz; Harom), 8.12 (1H, d, 3J(H,P) =8.0 Hz; Harom), 8.60 ppm
(1H, d, 3J(H,H) =5.6 Hz; Harom); 31P NMR (CD2Cl2, 162 MHz): d=86.0 (d,
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2
Cp*), 51.3 (CH), 51.6 (CH), 101.6 (Cq from Cp*), 121.3 (d, J(C,P)
=
4
7.6 Hz; CH), 125.3 (CH), 127.1 (CH), 127.9 (d, J(C,P) =2.8 Hz; CH), 128.1
(CH), 128.8 (CH), 128.9 (d, 4J(C,P) =2.3 Hz; CH), 130.9 (d, 3J(C,P) =5.4 Hz;
CH), 136.2 (CH), 137.2 (d, 2J(P,C) =10.1 Hz; Cq), 138.0 (Cq), 138.9 (CH),
139.0 (CH), 139.1 (CH), 140.5 (d, 3J(C,P) =2.9 Hz; Cq), 154.7 (CH), 159.3
(Cq),
159.5 ppm
(Cq);
elemental
analysis
53.77,
calcd
H
(%)
N
for
1.90;
C32H33NPOCl2Rh·CH2Cl2 (791.73 gmolÀ1):
C
4.79,
found: C 53.86, H 4.85, N 1.89.
Chem. Eur. J. 2013, 19, 3676 – 3684
ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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Received: October 10, 2012
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Published online: January 29, 2013
3684
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ꢂ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 3676 – 3684