Reversible Ligand Protonation of a Mn(I) PCP Pincer Complex to Afford a Complex with an η2-Caryl-H Agostic Bond

Article abstract of DOI:10.1021/acs.organomet.8b00193

The first manganese PCP pincer complex, [Mn(PCP^NEt-iPr)(CO)₃], was obtained by treating [Mn₂(CO)₁₀] and 2-chloro-N¹,N³-bis(diisopropylphosphanyl)-N¹,N³-diethylbenzene-

Full text of DOI:10.1021/acs.organomet.8b00193

Article
Cite This: Organometallics XXXX, XXX, XXX−XXX
Reversible Ligand Protonation of a Mn(I) PCP Pincer Complex To
Afford a Complex with an η2‑Caryl−H Agostic Bond
Daniel Himmelbauer,† Berthold Stoger,‡ Luis F. Veiros,§ and Karl Kirchner*,†
̈
‡
†Institute of Applied Synthetic Chemistry and X-Ray Center, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna,
Austria
§Centro de Química Estrutural, Instituto Superior Tec
́
nico, Universidade de Lisboa, Av. Rovisco Pais No. 1, 1049-001 Lisboa,
Portugal
S
* Supporting Information
ABSTRACT: The first manganese PCP pincer complex, [Mn(PCPNEt-iPr)(CO)3], was obtained by treating [Mn2(CO)10] and
2-chloro-N1,N3-bis(diisopropylphosphanyl)-N1,N3-diethylbenzene-1,3-diamine (P(C-Cl)PNEt-iPr) in CH3CN under solvothermal
conditions in a sealed microwave glass tube for 8 h at 140 °C. Protonation of this complex with HBF4·Et2O leads to the
formation of the cationic Mn(I) complex [Mn(κ3P,CH,P-P(CH)PNEt-iPr)(CO)3]BF4, which features an η2-Caryl−H agostic bond.
There was no evidence for the formation of a Mn(III) hydride species. The agostic C−H bond is comparatively acidic, and even
relatively weak bases, such as NEt3, deprotonate this bond to re-form the starting material [Mn(PCPNEt-iPr)(CO)3]; protonation
is fully reversible. Substitution of one CO ligand was achieved upon treatment with NO+, affording the cationic complex
[Mn(PCPNEt-iPr)(CO)2(NO)]+, where the two CO ligands are trans to one another.
an η2-Caryl−H agostic bond. First-row transition-metal PCP
pincer complexes featuring an agostic C−H bond are
comparatively rare (Chart 1).3−6 X-ray structures of the new
complexes are presented.
INTRODUCTION
■
Pincer complexes play an important role in transition-metal
chemistry and have received enormous attention over the last
few decades.1,2 PCP pincer complexes, where the ligands bear
phosphine donors tethered via CH2, O, or NR linkers to an
aromatic benzene backbone in the two ortho positions, are still
some of the most common types. This architecture allows easy
access to a broad variety of structural, electronic, and
stereochemical modifications. It is thus not surprising that
this type of complex plays an important role in transition-metal
chemistry and has attracted a great deal of attention over the
past decade.2 As far as manganese is concerned, to the best of
our knowledge, there has been no PCP complex reported in the
literature.
Instead of a directed intramolecular cyclometalation of the
ipso C−H bond, we utilize here the oxidative addition of the
C−Cl bond of the ligand precursor 2-chloro-N1,N3-bis-
(diisopropylphosphanyl)-N1,N3-diethylbenzene-1,3-diamine
(1; P(C-Cl)PNEt-iPr) to the Mn(0) complex [Mn2(CO)10] as a
synthetic entry into manganese PCP pincer chemistry. We
describe here the synthesis, characterization, and reactivity of
the first Mn(I) PCP pincer complex, [Mn(PCPEt-iPr)(CO)3],
which undergoes reversible protonation to yield a complex with
RESULTS AND DISCUSSION
■
A suspension of the Mn(0) complex [Mn2(CO)10] and 1 equiv
of P(C-Cl)PNEt-iPr (1) in CH3CN was placed in a sealed glass
tube and stirred for 8 h at 140 °C. After workup, the analytically
pure Mn(I) complex [Mn(PCPNEt-iPr)(CO)3] (2) was
obtained in 40% isolated yield (Scheme 1). The metal center
has been formally oxidized from Mn(0) to Mn(I), thereby
breaking the Mn−Mn bond. The chlorinated ligand 1 acts as an
oxidizing agent. The fate of chlorine and the remaining Mn
fragment has not been established as yet. Complex 2 was fully
1
characterized by a combination of H, 13C{1H}, and 31P{1H}
NMR spectroscopy, IR spectroscopy, and HR-MS analysis.
Characteristic features in the 13C{1H} NMR spectrum comprise
Special Issue: In Honor of the Career of Ernesto Carmona
Received: April 2, 2018
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.8b00193
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[Mn(κ3P,CH,P-P(CH)PNEt-iPr)(CO)3]BF4 (3) in 91% isolated
yield (Scheme 1). This complex features an η2-Caryl−H agostic
bond. There was no evidence for the formation of the Mn(III)
hydride complex [Mn(PCPNMe-iPr)(CO)3(H)]+ as a result of
an electrophilic attack of H+ at the metal center. DFT
calculations revealed that such a species is less stable by 27
kcal/mol. The agostic proton is comparatively acidic, and thus
even relatively weak bases, such as NEt3, deprotonate this bond
to re-form the starting material 2. Accordingly, protonation of 2
is fully reversible (Scheme 1).
Chart 1. Examples of First-Row Transition-Metal PCP and
Related Pincer Complexes Featuring a C−H Agostic
Interaction
1
Complex 3 was characterized by H, 13C{1H}, and 31P{1H}
NMR spectroscopy, IR, HR-MS, and X-ray crystallography. An
1
important feature of the H NMR spectrum is the high-field
shift of the proton attached to the ipso carbon, giving rise to a
triplet at 1.36 ppm (JHP = 4.6 Hz) (Figure 2). In the 13C{1H}
Scheme 1. Synthesis of Complexes 2 and 3
a triplet resonance at 132.8 ppm (JPC = 10.7 Hz) assigned to
the ipso carbon of the benzene moiety and two unresolved
broad low-field resonances in a 2:1 ratio at 225.2 and 222.6
ppm, respectively, assignable to the carbonyl carbon atoms
trans and cis to the ipso carbon. In the IR spectrum three strong
absorption bands typical of a mer CO arrangement are observed
at 1912, 1900, and 1884 cm−1, respectively. In addition to the
spectroscopic characterization, the solid-state structure of 2 was
determined by single-crystal X-ray diffraction.
1
Figure 2. Section of the H−13C HSQC spectrum of 3 in CD2Cl2
exhibiting a cross peak between the agostic H1 and C1 atoms.
NMR spectrum the ipso carbon atom exhibits a signal at 48.8
ppm (cf. 132.8 ppm in 2) and the three CO ligands give rise to
low-field resonances at 221.6, 216.8, and 215.3 ppm. The
A structural view is depicted in Figure 1 with selected bond
distances given in the captions. The coordination geometry
1
relatively low JHC coupling constant of 126.6 Hz, in
comparisonb to 161.0 and 165.1 Hz for the other two aromatic
C−H bonds, is also characteristic of a strong C−H metal
interaction.5−14 Complex 3 exhibits three strong bands at 1942,
1899, and 1880 cm−1 in the IR spectrum.
A structural view of 3 is depicted in Figure 3a. The overall
geometry about the manganese center is also best described as
Figure 1. Structural view of [Mn(κ3P,C,P-PNPNEt-iPr)(CO)3] (2)
showing 50% thermal ellipsoids (H atoms omitted for clarity).
Selected bond lengths (Å) and bond angles (deg): Mn1−C23
1.804(3), Mn1−C25 1.820(3), Mn1−C24 1.825(3), Mn1−C1
2.049(2), Mn1−P2 2.2551(7), Mn1−P1 2.2648(8); P2−Mn1−P1
163.37(3), C25−Mn1−C24 163.6(1), C23−Mn1−C1 179.0(1).
around the manganese center corresponds to a distorted
octahedron. In particular, the carbonyl−metal−carbonyl angles
of the CO ligands trans to one another and the P1−Mn−P2
angle deviate significantly from 180°, being 163.6(1) and
163.37(3)°, respectively. The Mn−C1 bond length is 2.049(2)
Å.
Figure 3. (a) Structural view of [Mn(κ3P,CH,P-P(CH)PNEt-iPr)-
(CO)3]BF4 (3). showing 50% thermal ellipsoids (most H atoms
omitted for clarity). Selected bond lengths (Å) and bond angles (deg):
Mn1−C24 1.789(2), Mn1−C23 1.839(2), Mn1−C25 1.845(2),
Mn1−C1 2.249(2), Mn1−P2 2.3142(8), Mn1−P1 2.3147(7), Mn1−
H1 1.99(3), C1−H1 0.97(3); P2−Mn1−P1 157.74(2), C23−Mn1−
C25 171.01(9), C24−Mn1−C1 164.67(9). (b) HOMO-4 of complex
3.
Protonation of [Mn(PCPNEt-iPr)(CO)3] (2) with HBF4·
Et2O leads to the formation of the cationic Mn(I) complex
B
DOI: 10.1021/acs.organomet.8b00193
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distorted trigonal bipyramidal where the carbonyl ligands and
the agostic η2-Caryl−H bond define the equatorial plane and the
phosphine moieties the axial positions. The distance between
the ipso carbon and the Mn atom is extremely long (2.249(2) Å
vs 2.049(2) Å in 2) relative to regular iron−carbon σ bonds.
The H(1) atom (which was located in difference Fourier maps
and refined freely) interacts with the Mn center (1.99(3) Å),
being CMn = −0.48 and CNO = 0.16, respectively. The Mn−
N(NO) bond is rather stronger with a WI of 1.32.
A structural view of 4 is depicted in Figure 4 with selected
bond distances and angles reported in the caption. Complex 4
1
which was also evident from the H NMR spectrum of 3. It is
noteworthy that this hydrogen is severely removed from the
aromatic plane by ca. 31° (cf. in related Ru, Rh, and Pd
complexes these angles are in the range of 14−30°,10−19 while
in Cr, Mo,4 and Co5 these angles are 32, 28, and 35°,
respectively). The C1−H1 bond length of 0.97(3) Å is in the
range observed in X-ray diffraction measurements for
unactivated hydrocarbons (e.g., 1.08 Å in C6H6).
Figure 4. Structural view of trans-[Mn(PNPNEt-iPr)(CO)2(NO)]BF4
(4) showing 50% thermal ellipsoids (H atoms and BF4− anion omitted
for clarity). Selected bond lengths (Å) and bond angles (deg): Mn1−
C1 2.064(2), Mn1−N3 1.676(2), Mn1−C23 1.864(2), Mn1−C24
1.866(2), Mn1−P1 2.3115(8), Mn1−P2 2.3123(7); P1−Mn1−P2
162.58(3), C23−Mn1−C24 159.4(1), Mn1−N3−O3 178.5(2).
The electronic structure of 3 has been investigated by DFT
calculations (frontier orbitals are shown in the Supporting
Information). The pattern obtained is typical of a d6 metal
complex with a distorted-octahedral geometry, with three filled
orbitals based on metal xy, xz, and yz, corresponding to the t2g
set of a perfect octahedron, and two empty eg orbitals, with
strong participation of metal z2 and x2 − y2, respectively. The
HOMO-4 represents the π back-donation from the metal d
orbital to the C−H σ-antibonding orbital, which is character-
istic of an agostic bond (Figure 3b). In addition, there are
significant Mn−C and Mn−H interactions with distances of
2.29 and 1.94 Å, respectively, and Wiberg indices of 0.18 and
0.05, by the same order. The C−H bond also reflects the
agostic interaction, being longer (1.10 Å) and weaker (WI =
0.78) than the other C(aryl)−H bonds (1.08 Å, WI = 0.90).
The CO ligands in [Mn(PCPNEt-iPr)(CO)3] (2) are
substitutionally inert, and ligand exchange with CNtBu, even
at elevated temperatures, failed. However, treatment of
adopts a strongly distorted octahedral geometry around the
metal center with the CO ligands in trans positions to one
another. The P−Mn−P and C(CO)−Mn-C(CO) angles are
162.6 and 159.4°, respectively.
CONCLUSION
■
In summation, we described the synthesis of the first
manganese PCP pincer complex, [Mn(PCPNEt-iPr)(CO)3].
This compound was obtained by treating the Mn(0) precursor
[Mn2(CO)10] and 2-chloro-N1,N3-bis(diisopropylphosphanyl)-
N1,N3-diethylbenzene-1,3-diamine (P(C−Cl)PNEt-iPr) in
CH3CN under solvothermal conditions in a sealed microwave
glass tube for 18 h at 170 °C. This reaction involves a one-
electron oxidation of the precursor. Protonation of [Mn-
(PCPNEt-iPr)(CO)3] with HBF4·Et2O leads to the formation of
the cationic Mn(I) complex [Mn(κ3P,CH,P-P(CH)PNEt-iPr)-
(CO)3]BF4, which features an η2-Caryl−H agostic bond. There
was no evidence for the formation of a Mn(III) hydride species
as a result of an electrophilic attack of the proton at the metal
center. The agostic C−H bond is comparatively acidic, and
even relatively weak bases, such as NEt3, deprotonate this bond
to re-form the starting material [Mn(PCPNEt-iPr)(CO)3]; thus,
protonation is fully reversible. Substitution of one CO ligand
was achieved with NO+, leading to the formation of the cationic
complex trans-[Mn(PCPNEt-iPr)(CO)2(NO)]+.
[Mn(PCPNEt-iPr)(CO)3] (2) with NO+BF4 in CH2Cl2 at
−
room temperature led to the formation of the cationic Mn(I)
complex trans-[Mn(PCPNEt-iPr)(CO)2(NO)]BF4 (4) in 95%
isolated yield (Scheme 2). The respective cis isomer 5 was not
Scheme 2. Synthesis of Complex 4
observed. In fact, DFT calculations revealed that the trans
isomer is more stable than the cis isomer by ΔG = 6.3 kcal/mol.
It has to be noted that with NO gas (1 bar) no reaction took
place.
EXPERIMENTAL SECTION
■
General Information. All manipulations were performed under an
inert atmosphere of argon by using Schlenk techniques or in a MBraun
inert-gas glovebox. The solvents were purified according to standard
procedures.15 The deuterated solvents were purchased from Aldrich
and dried over 3 Å molecular sieves. The synthesis of 2-chloro-N1,N3-
bis(diisopropylphosphanyl)-N1,N3-diethylbenzene-1,3-diamine (1;
P(C-Cl)PNEt-iPr) is described in the Supporting Information. All
starting materials and substrates are known compounds and were used
Complex 4 exhibits in the IR spectrum three strong
absorption bands at 2017, 1913, and 1767 cm−1, respectively,
assignable to the symmetric and asymmetric CO and NO
stretching frequencies, respectively. The positive ion ESI MS of
4 in CH3CN displays the fully intact cationic molecule [M]+ at
m/z 536.2. The NO ligand is more strongly bound than the
CO ligands, as in the MS-MS spectra only a cationic fragment
at m/z 480.2 due to loss of two CO ligands is observed.
The frontier orbitals obtained for complex 4 (see the
Supporting Information) indicate a d6 complex and thus clearly
suggest a Mn(I) species with a NO+ ligand. This conclusion is
reinforced by the calculated charges of Mn and the NO ligand
as obtained from commercial resources. H, 13C{1H}, and 31P{1H}
1
NMR spectra were recorded on Bruker AVANCE-250, AVANCE-400,
and AVANCE-600 spectrometers. 1H and 13C{1H} NMR spectra were
referenced internally to residual protio solvent and solvent resonances,
respectively, and are reported relative to tetramethylsilane (δ 0 ppm).
31P{1H} NMR spectra were referenced externally to H3PO4 (85%) (δ
0 ppm). As reaction vessels 8 mL microwave vials from Biotage or
VWR with an aluminum Teflon septum cap were used.
C
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High-resolution accurate mass data mass spectra were recorded on a
hybrid Maxis Qq-aoTOF mass spectrometer (Bruker Daltonics,
Bremen, Germany) fitted with an ESI source. Measured accurate
mass data of the [M]+ ions for confirming calculated elemental
compositions were typically within 5 ppm accuracy. The mass
calibration was done with a commercial mixture of perfluorinated
trialkyltriazines (ES Tuning Mix, Agilent Technologies, Santa Clara,
CA, USA).
NMR (δ, 400 MHz, CD2Cl2, 20 °C): 148.4. IR (ATR, cm−1): 2017
(νCO), 1913 (νCO), 1767 (νNO). ESI-MS (CH3CN): [M]+ found 536.2,
calcd for C24H41MnN3O3P2 536.2.
X-ray Structure Determination. X-ray diffraction data of 2−4
were collected at T = 100 K under a dry stream of nitrogen on a
Bruker Kappa APEX II diffractometer system using graphite-
monochromated Mo Kα radiation (λ = 0.71073 Å) and fine sliced
φ and ω scans. Data were reduced to intensity values with SAINT, and
an absorption correction was applied with the multiscan approach
implemented in SADABS.16 The structure was solved by the dual-
space approach implemented in SHELXT17 and refined against F2 with
SHELXL.18 Non-hydrogen atoms were refined anisotropically. The H
atoms connected to C atoms were placed in calculated positions and
thereafter refined as riding on the parent atoms. The agostic H was
located from difference Fourier maps and refined freely. Molecular
graphics were generated with the program MERCURY.19
Computational Details. The computational results have been
achieved using the Vienna Scientific Cluster (VSC). Calculations were
performed using the GAUSSIAN 09 software package20 and the
B3LYP functional, without symmetry constraints. That functional
includes a mixture of Hartree−Fock21 exchange with DFT22 exchange
correlation, given by Becke’s three-parameter functional23 with the
Lee, Yang, and Parr correlation functional, which includes both local
and nonlocal terms.24,25 The basis set used for the geometry
optimizations consisted of the Stuttgart/Dresden ECP (SDD) basis
set26 to describe the electrons of Mn and a standard 6-31G(d,p) basis
set27 for all other atoms. Natural population analysis (NPA)28 and the
resulting Wiberg indices29 were used to study the electronic structure
and bonding of the optimized species. The NPA analysis was
performed with the NBO 5.0 program,30 and the three-dimensional
representations of the orbitals were obtained with Molekel.31
Synthesis. [Mn(PCPNEt-iPr)(CO)3] (2). A suspension of Mn2(CO)10
(90 mg, 0.23 mmol) and 1 equiv of 1 (100 mg, 0.23 mmol) in CH3CN
(1 mL) were placed in a 20 mL sealed-glass tube and stirred for 8 h at
140 °C. The reaction mixture was cooled to room temperature
without stirring. The white precipitate was transferred into a Schlenk
flask and dried under vacuum. The product was extracted with
acetone, and the solvent was removed under reduced pressure. The
crude product was purified by silica gel chromatography (hexane/ethyl
acetate 4/1) and recrystallized from hexane/ethyl acetate. Yield: 49 mg
(40%). Anal. Calcd for C25H41MnN2O3P2 (534.50): C, 56.18; H, 7.73;
1
N, 5.24. Found: C, 56.26; H, 7.69; N, 5.33. H NMR (δ, 600 MHz,
CD2Cl2, 20 °C): 6.88 (t, J = 7.8 Hz, 1H, CarH), 6.10 (d, J = 7.9 Hz,
2H, CarH), 3.48 (m, 4H, N-CH2), 2.68 (m, 4H, P-CH), 1.38 (dd, 12H,
J = 6.8 Hz, J = 14.9 Hz, CH-CH3), 1.25 (dt, J = 7.0 Hz, J = 14.3 Hz,
18H, CH−CH3, CH2−CH3). 13C{1H} NMR (δ, 600 MHz, CD2Cl2,
20 °C): 225.2 (br, CO), 222.6 (t, J = 24.1 Hz, CO), 157.3 (t, J = 14.2
Hz, C-N), 132.8 (t, J = 10.7 Hz, C-Mn), 125.2 (s, CarH), 101.7 (t, J =
5.2 Hz, CarH), 41.3 (s, CH2), 32.3 (m, P-CH), 20.3 (s, CH-CH3), 19.3
(s, CH-CH3), 14.4 (s, CH2-CH3). 31P{1H} NMR (δ, 250 MHz,
CD2Cl2, 20 °C): 162.5 (s, P). HR-MS (ESI+, CH3CN/MeOH + 1%
H2O): m/z calcd for C25H41MnN2O3P2 [M]+ 534.1973, found
534.1964. IR (ATR, cm−1): 1912 (νCO), 1900 (νCO), 1884 (νCO).
[Mn(κ3P,CH,P-P(CH)PNEt-iPr)(CO)3]BF4 (3). A solution of 2 (34 mg,
0.06 mmol) in CH2Cl2 (4 mL) was treated with HBF4·Et2O (10 μL,
0.07 mmol, d = 1.19 g/mL), and the reaction mixture was stirred for
15 min at room temperature. All volatiles were then removed under
vacuum, and a red solid was obtained, which was washed three times
with diethyl ether and dried under vacuum. Yield: 37 mg (91%).
Crystals were obtained by pentane diffusion into a THF solution of 2.
Anal. Calcd for C25H42BF4MnN2O3P2 (622.31): C, 48.25; H, 6.80; N,
ASSOCIATED CONTENT
* Supporting Information
■
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00193.
1
4.50. Found: C, 47.96; H, 6.91; N, 4.58. H NMR (δ, 600 MHz,
Experimental details of organic starting materials, ligand
CD2Cl2, 20 °C): 7.63 (t, J = 8.2 Hz, 1H, CarH), 6.52 (d, J = 8.2 Hz,
2H, CarH), 3.68 (m, 2H, N-CH2), 3.49 (m, 2H, N-CH2), 2.84 (m, 4H,
P-CH), 1.47 (m, 12H, CH-CH3), 1.36 (t, J = 4.6 Hz, 1H, Cipso-H-Mn),
1.25 (m, 18H, CH-CH3, CH2-CH3). 13C{1H} NMR (δ, 600 MHz,
CD2Cl2, 20 °C): 221.7 (br, CO), 216.7 (t, J = 17.9 Hz, CO), 215.0 (t, J
= 19.1 Hz, CO), 169.6 (t, J = 9.3 Hz, C-N), 141.4 (s, CarH), 108.9 (t, J
= 4.0 Hz, CarH), 48.8 (s, Cipso-Mn), 41.9 (s, CH2), 33.6 (m, P-CH),
31.9 (m, P-CH), 18.8 (s, CH-CH3), 18.5 (s, CH-CH3), 18.2 (t, J = 4.1
Hz, CH-CH3), 18.0 (t, J = 2.7 Hz, CH-CH3), 12.9 (s, CH2-CH3).
31P{1H} NMR (δ, 250 MHz, CD2Cl2, 20 °C): 148.8. HR-MS (ESI+,
CH3CN/MeOH + 1% H2O): m/z calcd for C25H42MnN2O3P2+ [M]+
535.2046, found 535.2042. IR (ATR, cm−1): 1942 (νCO), 1899 (νO),
1880 (νCO).
1
synthesis, and H, 13C{1H}, and 31P{1H} NMR spectra
of all complexes and ligand precursors (PDF)
Optimized Cartesian coordinates for DFT-calculated
structures of 3 and 4 (XYZ)
Accession Codes
CCDC 1833635−1833636 and 1844779 contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge via www.ccdc.cam.ac.uk/data_request/
cif, or by emailing data_request@ccdc.cam.ac.uk, or by
contacting The Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
trans-[Mn(PCPNEt-iPr)(CO)2(NO)]BF4 (4). To a solution of 2 (118
mg, 0.22 mmol) in CH2Cl2 (5 mL) was added NOBF4 (30 mg, 0.26
mmol), and the mixture was stirred for 18 h at room temperature,
whereupon the solution turned from pale yellow to dark red. The
mixture was then filtered through Celite, and all volatiles were
removed under reduced pressure. The remaining solid was washed
three times with n-pentane and dried under vacuum. Yield: 118 mg
(94%). Red crystals were obtained by n-pentane diffusion into an
acetone solution of 4. Anal. Calcd for C24H41BF4MnN3O3P2 (623.30):
AUTHOR INFORMATION
Corresponding Author
*K.K.: e-mail, karl.kirchner@tuwien.ac.at; tel, (+43) 1 58801
163611; fax, (+43) 1 58801 16399.
■
ORCID
Luis F. Veiros: 0000-0001-5841-3519
Karl Kirchner: 0000-0003-0872-6159
1
C, 46.25; H, 6.63; N, 6.74. Found: C, 46.35; H, 6.51; N, 6.82. H
NMR (δ, 400 MHz, CD2Cl2, 20 °C): 7.17 (t, J = 8.1 Hz, 1H, CarH),
6.31 (d, J = 8.1 Hz, 2H, CarH), 3.59 (m, 4H, N-CH2), 3.04 (m, 4H, P-
CH), 1.44 (ddd, 24H, J = 27.4 Hz, J = 17.0 Hz, J = 7.3 Hz, CH-CH3),
1.33 (t, J = 7.0 Hz, 6H, CH2-CH3). 13C{1H} NMR (δ, 400 MHz,
CD2Cl2, 20 °C): 157.3 (t, J = 12.2 Hz, C-N), 131.5 (s, CarH), 106.7 (t,
J = 5.0 Hz, CarH), 42.3 (s, CH2), 32.7 (t, J = 11.8 Hz, P-CH), 19.8 (s,
CH-CH3), 18.8 (s, CH-CH3), 14.0 (s, CH2-CH3). The resonances of
the ipso carbon and the CO ligands could not be detected. 31P{1H}
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We dedicate this article to Professor Ernesto Carmona on the
occasion of his 70th birthday. Financial support by the Austrian
Science Fund (FWF) is gratefully acknowledged (Project No.
D
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P29584−N28). L.F.V. acknowledgesthe Fundaca
Article
(18) Spek, A. L. Acta Crystallogr., Sect. D: Biol. Crystallogr. 2009, 65,
148−155.
(19) Macrae, C. F.; Edgington, P. R.; McCabe, P.; Pidcock, E.;
Shields, G. P.; Taylor, R.; Towler, M.; van de Streek, J. J. Appl.
Crystallogr. 2006, 39, 453−457.
̧
o para a
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DOI: 10.1021/acs.organomet.8b00193
Organometallics XXXX, XXX, XXX−XXX