Synthesis, structure and theoretical study of two rhodium(I) complexes [Rh(TropNMe)(CO)(PPh3)] and [Rh(Trop)(CO)(PPh3)] · Acetone

Article abstract of DOI:10.1016/j.poly.2007.07.039

Rhodium(I) complexes [Rh(TropNMe)(CO)(PPh₃)] (TropNMe = 2-(N-methylamino)tropone, ONC₈H₉) (1) and [Rh(Trop)(CO)(PPh₃)] · Acetone (Trop = Tropolone, O₂C₇H₆) (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. A distorted square planar geometry about the rhodium(I) metal centre is observed in both compounds 1 and 2. Substitution of an oxygen atom with a methyl functionalized nitrogen atom does not significantly alter the bond distances and angles in the rhodium(I) complex. A theoretical study at B3LYP/6-31G(d) (main group) and LANL2DZ (Rh) level is presented to clarify the solid state behaviour of these complexes.

Full text of DOI:10.1016/j.poly.2007.07.039

Available online at www.sciencedirect.com
Polyhedron 26 (2007) 5324–5330
www.elsevier.com/locate/poly
Synthesis, structure and theoretical study of two
rhodium(I) complexes [Rh(TropNMe)(CO)(PPh3)] and
[Rh(Trop)(CO)(PPh3)] Æ Acetone
*
G. Steyl
Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
Received 22 February 2007; accepted 29 July 2007
Available online 31 August 2007
Abstract
Rhodium(I) complexes [Rh(TropNMe)(CO)(PPh3)] (TropNMe = 2-(N-methylamino)tropone, ONC8H9) (1) and [Rh(Trop)-
(CO)(PPh3)] Æ Acetone (Trop = Tropolone, O2C7H6) (2) have been synthesized and characterized by single-crystal X-ray diffraction anal-
ysis. A distorted square planar geometry about the rhodium(I) metal centre is observed in both compounds 1 and 2. Substitution of an
oxygen atom with a methyl functionalized nitrogen atom does not significantly alter the bond distances and angles in the rhodium(I)
complex. A theoretical study at B3LYP/6-31G(d) (main group) and LANL2DZ (Rh) level is presented to clarify the solid state behaviour
of these complexes.
ꢀ 2007 Elsevier Ltd. All rights reserved.
Keywords: Rhodium; Tropolone; Methylaminotropone; Crystal structure; Theoretical study
1. Introduction
flates or tosyloxy groups [13], followed by the addition of
an equivalent amount of nitrogen substrate [14]. Thus, a
host of amino and anilino derivatives of tropolone have
been reported [3,13,14]. The ability to add electron donat-
ing or withdrawing substituents to the nitrogen atom with
varying functional groups increases the range of applica-
tions in transition metal chemistry.
As part of a continuing investigation on these types of
complexes, the crystal structures of [Rh(TropNMe)(CO)-
(PPh3)] (1) and [Rh(Trop)(CO)(PPh3)] Æ Acetone (2) are
presented. Spectroscopic data and theoretical calculations
on the complexes are also reported.
The application of tropolonato ligands in organometal-
lic chemistry has received considerable attention [1–3].
Among others, radiopharmaceuticals [M(Trop)3] (M =
Ga3+, In3+) [4], catalyst precursors for rhodium hydro-
formylation [5] and alkyne hydroamination [6] systems.
The effect of functionalization of the tropolone backbone
in conjunction with transition metal centres have been
investigated in the recent past [5,7,8]. A range of rho-
dium(I) and palladium(II) complexes have been reported
to date, indicating that the bidentate-O,O system plays
an important role in the character of these complexes [9–
12].
2. Experimental
The substitution of either the 2-(aminotropone) or 1,2-
(aminotropoimine) position with nitrogen donor atoms is
readily achieved through good leaving groups such as tri-
Synthesis of 2-(N-methylamino)tropone (TropNMe)
was done according to the literature procedure [13,14],
while all other ligands were obtained from commercially
available sources. FT-NMR spectra were recorded on a
Bruker AXS300 and AvanceII 600 at 25 ꢁC in CDCl3,
*
Tel.: +27 051 401 9526; fax: +27 051 444 6384.
E-mail address: geds12@yahoo.com
0277-5387/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.07.039

G. Steyl / Polyhedron 26 (2007) 5324–5330
5325
chemical shifts are reported in ppm. IR spectra in KBr pel-
lets were recorded in the range of 4000–600 cmꢀ1 on a Bru-
ker Tensor 27.
2.1.4. [Rh(Trop)CO(PPh3)] Æ Acetone (2)
[Rh(Trop)(CO)2] (20 mg, 0.068 mmol) was dissolved in
the minimum amount of warm acetone (ca. 2 ml) to which
was added PPh3 (20 mg, 0.075 mmol). The reaction mix-
ture was allowed to evaporate and crystals suitable for
X-ray crystallography were obtained as yellow blocks
2.1. Synthesis
1
2.1.1. [Rh(TropNMe)(CO)2]
(yield: 30 mg, 78%). H NMR (300 MHz, CDCl3, 25 ꢁC):
RhCl3 Æ xH2O (100 mg, 0.44 mmol) was dissolved in the
minimum amount of DMF (ca. 3 ml) and refluxed for
30 min. until the solution turned pale yellow. The solution
was treated with HTropNMe (77 mg, 0.57 mmol), precipi-
tated with ice-water and separated by centrifuge. The com-
plex was recrystallised from acetone (ca. 10 ml) (yield:
7.67 (m, 6H), 7.40 (m, 9H), 7.28 (m, 2H), 6.97 (m, 3H),
2.15 (s, 3H). 13C NMR (150.97 MHz, CD2Cl2, 25 ꢁC):
31.16 (s), 126.47 (s), 127.36 (s), 127.46 (s), 128.81 (d,
11.14 Hz), 131.08 (s), 133.43 (d, 51.21 Hz), 134.83 (d,
11.19 Hz), 137.07 (s), 137.23 (s), 184.64 (s), 185.49 (s),
1
2
190.15 (dd, JRh–C 76.18 Hz, JP,C 25.31 Hz), 206.95 (s).
1
1
117 mg, 70%). H NMR (300 MHz, CDCl3, 25 ꢁC): 7.32
31P NMR 48.80 (d, JRh–P 173.10 Hz). IRKBr (mRh–CO
)
(m, 2H), 7.12 (d, 1H), 6.95 (d, 1H), 6.81 (t, 1H), 1.56 (s,
3H). 13C NMR (150.97 MHz, CD2Cl2, 25 ꢁC): 45.8 (d,
1JN–C 3.6 Hz, CH3), 118.10 (d, 1.82 Hz), 122.30 (d,
1974 cmꢀ1, IRAcetone (mRh–CO) 1978 cmꢀ1. Micro-analytical
data: Anal. Calc. for RhPO4C28H26: C, 60.01; H, 4.68.
Found: C, 60.46; H, 4.62%.
1
2.72 Hz), 125.07 (s), 135.51 (s), 135.87 (s), 169.41 (d, JN–
1
1.73 Hz), 181.47 (s), 187.17 (d, JRh–C 64.78 Hz), 187.90
2.2. Crystallography
C
(d, JRh–C 71.55 Hz). IRKBr (mRh–CO) 2053, 1978 cmꢀ1
,
1
IRAcetone (mRh–CO) 2070, 2000 cmꢀ1. Micro-analytical data:
Anal. Calc. for RhO3C10H8N: C, 40.98; H, 2.75; N, 4.78.
Found: C, 41.53; H, 2.85; N, 4.85%.
The data collection was done on a Bruker Apex2 4K
˚
CCD diffractometer using Mo Ka (0.71073 A) and x-scans
at 100(2) K. After completion the first 50 frames were
repeated to check for decay, of which none was observed.
All reflections were merged and integrated with SAINT-PLUS
[15] and were corrected for Lorentz, polarization and
absorption effects using SADABS [16]. The structures were
solved by the heavy atom method and refined through
2.1.2. [Rh(Trop)(CO)2]
RhCl3 Æ xH2O (100 mg, 0.44 mmol) was dissolved in the
minimum amount of DMF (ca. 3 ml) and refluxed for
30 min. until the solution turned pale yellow. The solution
was treated with HTrop (66 mg, 0.57 mmol), precipitated
with ice-water and separated by centrifuge. The complex
was recrystallised from acetone (ca. 10 ml) (yield: 68 mg,
full-matrix least-squares cycles using the SHELX-97 [17]
P
package with (iFoj ꢀ jFci)2 being minimized. All non-H
atoms were refined with anisotropic displacement parame-
ters, while H atoms were constrained to parent atom sites
1
56%). H NMR (300 MHz, CDCl3, 25 ꢁC): 7.68 (dd, 2H),
7.54 (m, 2H), 7.25 (dd, 1H). 13C NMR (150.97 MHz,
using a riding model (aromatic C–H = 0.93 A; aliphatic
˚
˚
CD2Cl2, 25 ꢁC): 128.22 (s), 130.20 (s), 138.28 (s), 184.49
C–H = 0.96 A). The graphics were done with the DIAMOND
1
(s), 184.96 (d, JRh–C 72.74 Hz). IRKBr (mRh–CO) 2074,
[18] Visual Crystal Structure Information System software.
The crystals of 2 included 0.75 acetone solvate molecule per
asymmetric unit, which was disordered of two sites along
the a-axis. The crystal structure of 2 has been reported pre-
viously, however, the authors failed to locate and describe
the acetone solvate molecule [19] in the asymmetric unit.
Details of the crystal data, intensity measurements and
data processing are summarized in Table 1. Selected bond
distances and angles are given in Table 2.
2014 cmꢀ1, IRAcetone (mRh–CO) 2078, 2007 cmꢀ1. Micro-ana-
lytical data: Anal. Calc. for RhO3C10H8: C, 38.60; H, 1.80.
Found: C, 38.62; H, 1.85%.
2.1.3. [Rh(TropNMe)CO(PPh3)] (1)
[Rh(TropNMe)(CO)2] (20 mg, 0.068 mmol) was dis-
solved in the minimum amount of warm acetone (ca.
2 ml) to which was added PPh3 (20 mg, 0.075 mmol). The
reaction mixture was allowed to evaporate and crystals
suitable for X-ray crystallography were obtained as yellow
2.3. Computational data
1
blocks (yield: 20 mg, 55%). H NMR (300 MHz, CDCl3,
25 ꢁC): 7.67 (m, 5H), 7.39 (m, 10H), 7.12 (dd, 1H), 6.95
Calculation results were obtained using the GAUSSIAN-
03W [20] software package. DFT calculations were done
at the B3LYP [21] level of theory; for the main group ele-
ments the 6-31G(d) [22,23] basis set were incorporated
while the rhodium core was described by the LanL2DZ
[24] basis set. Optimised structures were verified as a mini-
mum through frequency analysis and from this data the
stretching frequencies of the carbonyl groups were identi-
fied. The isodesmic comparisons between different isomers
were calculated using the diketonato rhodium(I) dicar-
bonyl complexes to minimize error.
(t, 1H), 6.88 (t, 1H), 6.63 (d, 1H), 6.51 (t, 1H). 13C NMR
1
(150.97 MHz, CD2Cl2, 25 ꢁC): 45.77 (d, JN–C 3.64 Hz),
117.29 (d, 1.74 Hz), 120.04 (d, 1.63 Hz), 122.35 (d, 1.63),
128.74 (d, 9.15 Hz), 130.78 (s), 134.07 (t, 21.55,
25.35. Hz), 134.86 (d, 11.33 Hz), 168.37 (s), 181.77 (d,
1
2
5.45 Hz), 192.40 (dd, JRh–C 76.09 Hz, JP,C 23.53 Hz).
31P NMR 42.80 (d, JRh–P 146.88 Hz). IRKBr (mRh–CO
)
1
1943 cmꢀ1, IRAcetone (mRh–CO) 1962 cmꢀ1. Micro-analytical
data: Anal. Calc. for RhPO2C27H23N: C, 61.49; H, 4.40; N,
2.66. Found: C, 61.94; H, 4.49; N, 2.71%.

5326
G. Steyl / Polyhedron 26 (2007) 5324–5330
Table 1
Table 2
˚
Crystal data and structure refinement for complex 1 and 2
Selected bond distances (A) and angles (ꢁ) for 1 and 2
Compound
1
2
Compound
1
2
Empirical formula
Formula weight
T (K)
C27H23NO2PRh
527.34
100(2)
0.71073
triclinic
C55H40O7P2Rh2
1080.63
100(2)
0.71073
triclinic
Rh–O1
Rh–N1
Rh–O2
Rh–C01
Rh–P
2.0365(11)
2.0717(14)
2.045(2)
2.083(2)
1.805(3)
2.2232(11)
1.149(4)
1.462(5)
˚
Radiation k (A)
1.8038(15)
2.2628(4)
1.157(2)
Crystal system
Space group
Unit cell dimensions
ꢀ
ꢀ
P1 ðNo: 2Þ
P1 ðNo: 2Þ
C01–O01
C1–C2
1.476(2)
˚
a (A)
9.2395(3)
9.7982(3)
14.1171(5)
82.699(1)
88.676(1)
63.557(1)
1134.23(6)
8922
8.760(5)
10.388(5)
13.304(5)
89.256(5)
77.321(5)
83.850(5)
1174.3(10)
3927
O1–Rh–N1
O1–Rh–O2
C01–Rh–O1
C01–Rh–N1
C01–Rh–O2
C01–Rh–P
O1–Rh–P
N1–Rh–P
O2–Rh–P
Rh–C01–O01
77.63(5)
˚
b (A)
77.90(9)
174.03(12)
˚
c (A)
174.99(6)
98.92(6)
a (ꢁ)
b (ꢁ)
c (ꢁ)
98.55(12)
87.19(11)
96.40(8)
91.71(5)
91.85(3)
169.27(4)
3
˚
V (A )
Number of reflections
for cell measurement
h Range for cell
measurement (ꢁ)
Z
Dcalc (Mg/m3)
Absorption coefficient
(mmꢀ1
174.25(6)
176.9(3)
2.48–28.17
2.40–27.84
177.15(14)
1.2(2)
2
1
O1–C1–C2–N1
O1–C1–C2–O2
C8–N1–C2–C1
C3–C2–C1–C7
C7–C6–C5–C4
1.544
0.848
1.528
0.825
3.1(4)
178.23(14)
1.6(3)
2.6(3)
)
7.0(6)
1.1(8)
F(000)
536
546
Crystal shape/crystal
colour
plate/red
cuboid/yellow
Crystal size (mm)
Reflections collected/
unique
0.434 · 0.269 · 0.065 175 · 0.032 · 0.025
10583/4945
17585/5111
Reflections with
[I > 2r(I)]
Completeness to
4749
1
4337
1
h = 27ꢁ (%)
Absorption correction multi-scan
multi-scan
Maximum and
minimum
0.758 and 0.940
0.970 and 0.981
transmission
Data/restraints/
parameters
Goodness-of-fit on F2
Final R indices
[I > 2r(I)]
4945/0/283
5111/0/299
1.14
0.020
1.04
0.037
R indices (all data)
Largest difference in
peak and hole
0.021
0.048
˚
˚
0.472 (0.8 A Rh) and 1.368 (1.2 A C41) and
ꢀ1.084 (0.9 A Rh)
˚
˚
ꢀ0.627 (0.4 A C41)
Fig. 1. Molecular diagram showing the numbering scheme and displace-
ment ellipsoids (50% probability) in [Rh(TropNMe)(CO)(PPh3)] (1). The
first digit in the phenyl rings refers to the number of the ring, the second
digit to the number of the C atom in the ring (1–6). Hydrogen atoms
omitted for clarity.
ꢀ3
˚
(e A
)
3. Results and discussion
Details of the data collections and refinement parame-
ters of [Rh(TropNMe)CO(PPh3)] (1) and [Rh(Trop)CO-
(PPh3)] Æ Acetone (2) are reported in Table 1 and selected
geometrical parameters are summarized in Table 2. The
molecular structures with thermal ellipsoids and number-
ing schemes for 1 and 2 are shown in Figs. 1 and 3,
respectively.
containing carbonyl and triphenylphosphine moieties
(Fig. 1). A distorted square planar geometry about the rho-
dium(I) metal centre can be observed as defined by the
coordinated atoms. This distortion is observed as a devia-
tion from linearity of the angle formed by O–Rh–C (car-
bonyl) and N–Rh–P atoms, 174.98(5)ꢁ and 169.29(4)ꢁ,
respectively. The bidentate bite angle formed by O–Rh–N
is close to that observed for the unfunctionalised tropolo-
nato complexes in the order of ca. 80ꢁ [7–12]. It was
expected that the Rh–N and Rh–O bond distances would
differ, but in the current complex this variation is minimal.
Similar trends have been observed for O,O-tropolonato
3.1. Structural description
The molecular structure of [Rh(TropNMe)CO(PPh3)]
(1) is the first example of a mixed N,O-troponate complex

G. Steyl / Polyhedron 26 (2007) 5324–5330
5327
complexes [5,25,12] indicating that the seven-membered
ring system reduces the effect of functionalization of the
hetero-atoms.
The ordering in the solid state is significantly changed by
the presence of p–p stacking between respective 2-(N-meth-
ylamino)troponato ligands, which is observed in the order
˚
of 3.479(7) A, Fig. 2. The complex 1 adopts an arched con-
figuration as defined by the dihedral angle of 8.81(3)ꢁ
between the planes from the seven-membered troponato
backbone with that of the Rh(I) centre and the two O-
donor atoms. The rhodium(I) atom is in close proximity
to a hydrogen atom of the p-stacking troponato ring,
˚
Rhꢁ ꢁ ꢁH4 [1 ꢀ x, 2 ꢀ y, 1 ꢀ z], at a distance of 3.4157(1) A.
The molecular structure of [Rh(Trop)CO(PPh3)] Æ Ace-
tone (2) shows the coordination of the complex to exhibit
a slightly distorted square planar geometry about the rho-
dium(I) metal centre (Fig. 3). The deviation from planarity
can be observed from the angle formed by O–Rh–C (car-
bonyl) and O–Rh–P atoms, 174.0(1)ꢁ and 174.25(6)ꢁ,
respectively. The rhodium(I) metal centre is elevated above
Fig. 3. Molecular diagram showing the numbering scheme and displace-
ment ellipsoids (50% probability) in [Rh(Trop)(CO)(PPh3)] (2). The first
digit in the phenyl rings refers to the number of the ring, the second digit
to the number of the C atom in the ring (1–6). Hydrogen atoms and
disordered solvent molecule (acetone) omitted for clarity.
˚
the four coordinating atoms by 0.0143(5) A. The O–Rh–O
effect of the intermolecular hydrogen bonding and p-stack-
ing tropolonato functionalities create a three-dimensional
chain along the b-axis.
bidentate bite angle is close to that observed for unfunc-
tionalised tropolonato complexes in the order of 77.9(1)ꢁ
[7–12]. The difference in trans directing groups (PPh3 versus
CO) does not seem to play such a significant role, as
observed from the comparable Rh–O bond distances
(Table 2).
The change in geometrical parameters due to the intro-
duction of a methylamino moiety on the troponoid ring
system, does not seem to significantly affect the coordina-
tion to the rhodium(I) centre (Table 2). The trans influence
of N(Me) versus O was expected to be more prominent due
to the significant change observed in the infrared frequency
(solid state ꢂ30 cmꢀ1, solvent ꢂ16 cmꢀ1). A single note-
worthy difference between the two solid state structures
was the observed change of the Rh–P bond distance in
The rhodium(I) metal complex co-crystallises with an
acetone molecule in the asymmetric unit, exhibiting a
75% statistical disorder over two positions. No significant
hydrogen bonding is found between the complex and the
solvent molecule. The solvent molecule occupies voids cre-
ated by the efficient packing of the metal complex. Hydro-
gen bonding between a tropolonato oxygen atom (O2) and
a corresponding phenyl hydrogen atom (H14–C14) is
˚
the order of 0.04 A. The bite angle was also not affected
by the change of hetero-atoms and is nearly constant at
77ꢁ. This relative insensitivity of functionalization of the
troponoid ring might indicate that the cycloheptatriene sys-
tem counterbalances the different affects of hetero group
donor atoms.
˚
observed. The intermolecular hydrogen bond [2.585 A
˚
(O2ꢁ ꢁ ꢁH14), 3.509(4) A (O2, C14), 172.7(2)ꢁ] can be classified
as a weak interaction but is enhanced by the p–p stacking
˚
in the order of 3.39(1) A of the tropolonato moieties. The
˚
Fig. 2. Packing diagram of [Rh(TropNMe)CO(PPh3)] (1) along the ac-plane illustrating the p–p stacking [3.479(7) A] in the unit cell. Hydrogen atoms
omitted for clarity [symmetry code: 1 ꢀ x, 2 ꢀ y, 1 ꢀ z].

5328
G. Steyl / Polyhedron 26 (2007) 5324–5330
˚
3.2. Computational data
of ca. 0.16 A for the optimised structure (I). In order to
characterise the effect of functionalization, the cis-confor-
mation (PPh3-cis-NMe) is included and it clearly indicated
a strained orientation with the Rh–N bond distance
increasing significantly from the trans-conformation (I).
The affect of the relative strain can also be observed from
the energy difference between these two isomers which is
in the order of 50 kJ/mol, indicating that isomer I is the
preferred isomer in the solid state and solution.
Since complexes 1 and 2 tended to behave in a similar
fashion with respect to their geometrical parameters in
the solid state, a theoretical study was done to determine
if any significant differences could be observed at a theoret-
ical level between these compounds. The crystallographi-
cally determined structures were first optimised and
reported herein as compounds [Rh(TropNMe)CO(PPh3)]
(I) and [Rh(Trop)CO(PPh3)] (II), respectively. Secondly,
the [Rh(TropNMe)(CO)2] and [Rh(Trop)(CO)2] complexes
were optimised to construct an isodesmic reaction scheme
to compare complexes I and II relative to each other in
terms of stability. Finally, the cis-adduct (PPh3-cis-NMe)
of [Rh(TropNMe)CO(PPh3)] (I) was calculated to deter-
mine the structural change of the coordination sphere
due to steric factors, which could indicate a preference of
the trans-isomer over the cis-isomer. Calculated geometri-
cal parameters and energies are reported in Table 3.
Comparing the tropolonato complexes, 2 and II, no sig-
˚
nificant changes (less than 0.1 A) in Rh–O or Rh–C bond
distances are observed. The calculated Rh–P bond distance
˚
is slightly shorter than the reported value of 2.223 A in the
crystal structure (Table 3). The effect of rotation of the tri-
phenylphosphine on the O–Rh–O bite angle is less than 1ꢁ
and is in good agreement with the solid state structure. As
an illustrative example the rotation of the triphenylphos-
phine moiety to its higher energy conformer (a local mini-
mum) is only 25.2 kJ/mol. This clearly indicates that in
solution the two complexes (II and Rotation, Table 3)
are nearly in the same energetic environment.
To obtain a relative measure for the different complexes,
an isodesmic reaction scheme was constructed to illustrate
the energy difference profile between the 2-(N-methylami-
no)troponato (N,O; I) and tropolonato (O,O; II) com-
plexes, Table 3. Complex II is ca. 26 kJ/mol lower in the
energy profile than complex I, this is mostly from the addi-
tion of the methylamino moiety introducing strain into the
five-membered chelating ring of the rhodium(I) complex.
Although the energy difference is significantly large, it is
still within a comparable range for the two complexes if
one considers the rotation of the triphenylphosphine moi-
ety which is only 25.2 kJ/mol.
Geometrical results from the calculations confirmed that
these two types of complexes (I and II) have similar struc-
tural parameters, Table 3. The close structural relationship
between the calculated and crystallographic observed struc-
tures is best illustrated with a RMS overlay error of less
˚
than 0.376 and 0.133 A for 1/I and 2/II, respectively, see
Fig. 4. The increased RMS overlay error of complexes 1/
I are most probably due to solid state interactions as
described below.
The calculated Rh–N and Rh–O bond distances for the
2-(N-methylamino)troponato complexes (1 and I) do not
vary by much in contrast to that observed for the solid
state structure (1). Compared to the crystallographic data
of 1, an increase is observed in the Rh–P bond distance
Table 3
Selected calculated and solid state bond lengths (A), angles and torsion angles (ꢁ) for [Rh(Trop/TropNMe)CO(PPh3)]
˚
[Rh(Trop/TropNMe)(CO)2] [Rh(TropNMe)CO(PPh3)] [Rh(Trop)CO(PPh3)]
Rotation (II)
2.089
Trop
2.061
TropNMe
2.044
cis-Isomer
(I)
(1) X-ray
2.0365(11)
(2) X-ray
Rh–O
Rh–O
Rh–N
Rh–C
2.055
2.062
2.104
2.09
2.045(2)
2.083(2)
2.061
2.085
2.061
1.866
1.895
2.097
1.857
2.066
1.835
2.0717(14)
1.8038(15)
1.873
1.873
1.837
1.84
1.805(3)
Rh–P
2.399
77.82
2.42
2.2628(4)
77.63(5)
2.39
2.291
76.99
2.223(1)
77.90(9)
O–Rh–O
O–Rh–N
C–Rh–C
C–Rh–P
O–Rh–C
O–Rh–P
N–Rh–C
N–Rh–P
78.57
92.02
94.71
77.77
78.56
91.11
78.11
90.71
91.04
178.17
168.84
100.45
93.22
176.29
90.39
98.27
168.45
91.71(5)
174.99(6)
91.85(3)
98.92(6)
169.27(4)
93.67
95.33
93.21
91.2
96.27
95.53
87.19(11)
98.55(12)
96.40(8)
92.15
98.18
O–C–C–O
N–C–C–O
0.01
0.71
0.53
3.1(4)
0.01
0.46
1.67
1.2(2)
E(H)
Eiso (kJ/mol)
ꢀ756.596917
ꢀ776.030176
ꢀ1364.26666
ꢀ1364.27556
ꢀ1344.84265
ꢀ1344.85225
49.49
26.12
25.20a
0
a
Eiso = {[E(RhTrop(CO)2) + E(Rh(Trop)CO(PPh3)ROT)] ꢀ [E(RhTrop(CO)2) + E(Rh(Trop)CO(PPh3)(II))]} · 627.5 · 4.184.

G. Steyl / Polyhedron 26 (2007) 5324–5330
5329
Fig. 4. Overlayed structures of the calculated (grey) and solid state (black) structures of [Rh(TropNMe)(CO)(PPh3)] (left) and [Rh(Trop)(CO)(PPh3)]
˚
(right). Hydrogen atoms omitted for clarity. The RMS overlay error of 0.376 and 0.133 A does not include hydrogen atoms for the respective complexes.
4. Conclusion
this article can be found, in the online version, at
doi:10.1016/j.poly.2007.07.039.
The effect of substitution of a tropolonato oxygen atom
with a N-methylamino moiety does not significantly alter
the geometrical parameters of the rhodium(I) complex.
The structural similarity between 1 and 2 in the solid state
was confirmed by computational results. Finally, p–p
stacking could be observed for both the functionalised 2-
(N-methylamino)troponato and tropolonato rhodium(I)
complexes.
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