Reaction of a 2,4,6-triphenylphosphinine ferrate anion with electrophiles: A new route to phosphacyclohexadienyl complexes

Article abstract of DOI:10.1039/c6dt00336b

A novel, versatile route to phosphorus- and carbon-substituted η⁵-phosphacyclohexadienyl complexes was developed. Reaction of the anionic 2,4,6-triphenylphosphinine iron complex [K([18]crown-6)(thf)₂][Cp?Fe(PC₅Ph₃H₂)] (1) with selected main group element electrophiles afforded the new complexes [Cp?Fe(2-endo-H-PC₅Ph₃H₂)] (endo-3), [Cp?Fe(2-exo-H-PC₅Ph₃H₂)] (exo-3), [Cp?Fe(1-Me-PC₅Ph₃H₂)] (4), [Cp?Fe(1-Me₃Si-PC₅Ph₃H₂)] (5), [Cp?Fe(1-PPh₂-PC₅Ph₃H₂)] (6) and [Cp?Fe(2-BCat-PC₅Ph₃H₂)] (7, BCat = 2-benzo[d][1,3,2]dioxaborol-2-yl). Initial attack of the electrophile at phosphorus was observed, leading to a P-substitued phosphinine ligand. A subsequent rearragement occured in some cases, resulting in C-substituted phosphinine complexes endo-3, exo-3 and 7. The new complexes were characterized by ¹H, ³¹P{¹H}, and ¹³C{¹H} NMR spectroscopy, UV-vis spectroscopy and elemental analysis; their molecular structures were determined by X-ray crystallography.

Full text of DOI:10.1039/c6dt00336b

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PAPER
Reaction of a 2,4,6-triphenylphosphinine ferrate
anion with electrophiles: a new route to
phosphacyclohexadienyl complexes†
Cite this: Dalton Trans., 2016, 45,
8875
Christian M. Hoidn and Robert Wolf*
5
A novel, versatile route to phosphorus- and carbon-substituted η -phosphacyclohexadienyl complexes
was developed. Reaction of the anionic 2,4,6-triphenylphosphinine iron complex [K([18]crown-6)
(
[
(
(
thf)
Cp*Fe(2-endo-H-PC
4), [Cp*Fe(1-Me Si-PC
2 5 3 2
][Cp*Fe(PC Ph H )] (1) with selected main group element electrophiles afforded the new complexes
5
Ph
3
H
2
)] (endo-3), [Cp*Fe(2-exo-H-PC Ph
5
3
H
2
)] (exo-3), [Cp*Fe(1-Me-PC
5
Ph
3
3
H
2
2
)]
)]
3
5
Ph
H
3 2
)] (5), [Cp*Fe(1-PPh -PC Ph H )] (6) and [Cp*Fe(2-BCat-PC
2
5
3 2
5
Ph
H
7, BCat = 2-benzo[d][1,3,2]dioxaborol-2-yl). Initial attack of the electrophile at phosphorus was observed,
Received 23rd January 2016,
Accepted 18th April 2016
leading to a P-substitued phosphinine ligand. A subsequent rearragement occured in some cases, result-
ing in C-substituted phosphinine complexes endo-3, exo-3 and 7. The new complexes were character-
DOI: 10.1039/c6dt00336b
1
31
1
13
1
ized by H, P{ H}, and C{ H} NMR spectroscopy, UV-vis spectroscopy and elemental analysis; their
molecular structures were determined by X-ray crystallography.
www.rsc.org/dalton
5
donation of six π-electrons through an η -coordinated anionic
Introduction
carbocyclic backbone of the phosphacyclohexadienyl ligand
2
–7
Phosphacyclohexadienyls are six-membered heterocycles, (C
5
mode) is the most common motif.
Additionally, the
which can be distinguished from the related purely carbon- phosphorus atom may also become part of the coordinated
8
containing cyclohexadienyls by their ambidentate donor pro- π-system (C P unit and CPC mode, Fig. 1).
4
5
3
1
perties and versatile coordination behaviour (Fig. 1). The
While η -coordination is the most frequent coordination
mode, η -coordination can be found less often. The two elec-
1
tron donation of the P lone pair may be induced by additional
chelating donor moieties such as pyridyl and phosphasulfide
in the periphery of 1-substituted phosphacyclohexadienyl
1
,2,9–16
2
II
complexes.
Rare η -coordination was found in Pd and
II
17
3
1
Pt complexes, while a bridging η :η -mode was observed for
dinuclear Ni and Zr complexes.
1
,18
Phosphacyclohexadienyls thus are versatile ligands that
bind to a range of transition metals and have successfully
been applied in homogeneous catalysis, e.g. catalytic olefin
1
,5
polymerization and hydroformylation. Nevertheless, prepara-
tive methods are limited to merely three routes (Fig. 2). The
conventional method (exemplified in Fig. 2a) is based on the
initial synthesis of phosphacyclohexadienyl anions by reacting
a phosphinine with an organometallic nucleophile and sub-
Fig. 1 Overview of the versatile coordination modes of the ambiden-
tate 1-substituted, 2-substituted and 3-substituted phosphacyclohexa-
dienyl complexes; M = transition metal; R = organic residue; further
substituents on the phosphinine rings are omitted for clarity.
2
,9,11,17
sequent salt metathesis.
lished by Märkl in 1974. Nief and Fischer developed the
This method was first estab-
University of Regensburg, Institute of Inorganic Chemistry, D-93040 Regensburg,
Germany. E-mail: robert.wolf@ur.de; http://www.uni-regensburg.de/chemistry-
pharmacy/inorganic-chemistry-wolf/index.html
3
3
reduction of the phosphinine oxide complex C with HSiCl as
1
13
1
31
1
†
Electronic supplementary information (ESI) available: H, C{ H}, P{ H} and a more specialized approach (Fig. 2b) to the synthesis of hydro-
UV-vis spectra of complexes endo-3–7, crystallographic data of endo-3–7, and
details of the DFT calculations (relative thermal and free enthalpies of 2, endo-3
and exo–3). Full experimental details and crystallographic data of [Cp*Fe(1-
8
phosphacyclohexadienyl complexes. The P–H functionalized
complex D was formed as the kinetic product with an excess of
HSiCl3 at room temperature. The thermodynamically more
stable carbon-protonated isomer exo-F was obtained by reflux-
3 5 3 2
Ph Sn-PC Ph H )] (8). CCDC 1448678–1448684. For ESI and crystallographic
data in CIF or other electronic format see DOI: 10.1039/c6dt00336b
This journal is © The Royal Society of Chemistry 2016
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complexes endo-3, exo-3, and 4–7. The formation of 1-phospha-
cyclohexadienyls (where the substituents are attached to phos-
phorus) and 2-substituted phosphacyclohexadienyls (where the
substituent is connected to an adjacent carbon atom) is
observed. Consequently, the molecular structures of the com-
plexes display the C
ively (Fig. 1).
5 4
and the C P coordination mode, respect-
Results and discussion
Synthesis of novel phosphacyclohexadienyl complexes
We recently reported that the 1-hydrophosphacyclohexadienyl
complex 2 can be synthesized by reacting the cationic phosphi-
nine complex G with one equivalent LiBHEt (Fig. 2c). Assum-
3
ing that the protonation of the anionic complex 1 might give
the same product, 1 was treated with one equivalent of HCl-
(
2
OEt ) in THF. The reaction affords a mixture of compounds,
including 2 and the new compounds endo-3 and exo-3. The
latter are isomers of 2 and display 2-hydrophosphacyclohexa-
dienyl ligands. In the case of endo-3, the hydrogen atom in the
2-position of the phosphinine is attached to the metal-
coordinated face, causing the phenyl substituent to point to
the bottom. The diastereomer exo-3 formally results from pro-
tonation of the phosphinine ring at the remote face to the iron
center. Isomers 2, endo-3 and exo-3 are analogous to D, endo-F
and exo-F previously prepared by Nief and Fisher via a comple-
8
tely different route (Fig. 2b).
3
1
1
P{ H} NMR monitoring ([D
signal of 2 (−80 ppm) at −80 °C. Two additional signals at
0 ppm and −64 ppm arise from unknown intermediates,
which disappear at higher temperature. The signal of the start-
ing material 1 (−49 ppm) continuously decreased on slow
warming to 0 °C, whereas the signal of 2 increased. The
8
]THF, Fig. 3) revealed the
Fig. 2 Synthesis of phosphacyclohexadienyl complexes; Nu = H, NMe
2
,
1
7
Cp*; E = H, Me, SiMe
3
, PPh
2
; E’ = H, BCat.
ing a solution of C with an excess of HSiCl in toluene for signals of the 2-H-substituted species exo-3 (−162 ppm) and
3
three hours. When the reaction was stopped after 55 min, endo–3 (−137 ppm) were observed in low intensity at −30 °C;
complex E was identified as the main product. Isolated E their intensity increased significantly at 0 °C, whereas the
undergoes a quantitative isomerization to endo-F by refluxing signal of 2 decreased. An additional signal corresponding to
overnight.
an unidentified species became apparent at −14 ppm at
To our knowledge, endo-F is the only crystallographically −40 °C. This signal could plausibly arise from a by-product
8
characterized example of a 2-substituted phosphacyclohexadie- similar to complex E (−20.4 ppm) or a decomposition
3
1
1
4
nyl complex with the C P coordination mode so far. Using a product. The P{ H} NMR spectrum of the reaction mixture
5
different approach, we synthesized η -phosphacyclohexadienyl recorded at room temperature displays the signals of 2, exo-3,
iron complexes of type H by oxidizing the anionic penta- endo-3 as well as a few weak singlets of further unidentified
methylcyclopentadienyl complex 1 with iodine, followed by the species. The signal intensities did not change further after one
conversion of the resulting cationic complex G with nucleo- day. Stirring the raw product mixtures of 2, endo-3 and exo-3 at
7
31
1
piles (Fig. 2c). Nucleophilic attack occurs at the phosphorus 50 °C for several days ( P{ H} NMR monitoring) also did not
3
3
atom, giving 1-substituted λ σ -phosphacyclohexadienyl com- lead to a further change of the integral ratios.
plexes. While this route can in principle give access to a large
Even though 2 appears to be formed selectively at low temp-
family of complexes, a disadvantage is the required two-step erature, we were not able to isolate it as a pure material from
reaction sequence. In this paper, we report a new, complemen- reactions performed at −40 °C. However, 2 slowly converts to
tary route to phosphacyclohexadienyl complexes that is based exo-3 upon treatment with HCl(OEt ) (10 mol%) at room temp-
2
on the direct reaction of the anion 1 with electrophiles. The erature in [D ]THF. This indicates the rearrangement to be
8
application of this new method resulted in the synthesis and acid-catalysed. Attempts to optimise the reaction gave poorly
structural characterization of six new phosphacyclohexadienyl reproducible product mixtures. Thus, it appears difficult to
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3
1
1
Fig. 3
P{ H} NMR monitoring of the reaction of 1 with HCl(Et
2
O) in [D
8
]THF; * and ? designate unknown intermediates or products; the scheme
represents the proposed reaction pathway for the protonation of 1; DFT-calculated (BP86/def2-TZVP level) relative thermal enthalpies (ΔH at 298 K)
are given of 2, endo-3 and exo-3; the relative free enthalpies (ΔG at 298 K) are given in parentheses; see the ESI† for details.
access 2, exo-3 and endo-3 as pure compounds by protonationg
1
with HCl(OEt2).
The results of the monitoring experiment indicate that the
-hydrophosphacyclohexadienyl complex 2 is formed as the
1
main kinetic product along with two unidentified species
marked with an asterisk in Fig. 3). The 2-hydrophosphacyclo-
(
hexadienyl complexes endo-3 and exo-3 appear to be thermo-
dynamic products that form at higher temperatures. Indeed,
gas-phase DFT calculations performed at the BP86/def2-TZVP
level (see the Experimental section for details) indicate that
endo-3 and exo-3 are close in energy, while 2 was calculated to
be +7.0 kcal mol− less stable than endo-3 (Fig. 3, see the
Experimental section for details).
Scheme 1 Preparation of endo-3 and exo-3.
compounds are air-sensitive and dissolve well in n-hexane,
diethyl ether, toluene and THF.
Complexes 4–6 are accessible in a similar fashion in moder-
ate yields by reacting 1 with one equiv. of MeI, Me SiCl, and
Ph PCl (Scheme 2a–c).‡ The compounds are deeply coloured
2
crystalline solids that dissolve well in polar and apolar solvents
such as n-pentane, n-hexane, diethyl ether, toluene and THF.
1
Gratifyingly, the reaction of 1 with one equiv. isopropyl
chloride in THF at room temperature (Scheme 1) proceeded
cleanly, reproducibly affording a mixture of endo-3 and exo-3 in
a 65 : 35 ratio (NMR integration). The formation of 2 as an inter-
3
3
1
1
mediate was not observed by P{ H} NMR in this case, which
indicates that the reaction proceeds via a different mechanism.
Purification by column chromatography gave NMR-spectro-
scopically pure exo-3 and endo-3 after crystallization.
‡
The synthesis of 6 needs to be performed at −95 °C by slow addition of Ph
to a solution of complex 1. In this case, 6 was isolated in 38% yield. Addition of
Ph PCl at room temperature led to an almost quantitative formation of tetra-
2
PCl
Exo-3 was isolated as orange rods in 25% yield, whereas
pure endo-3 crystallized as orange plates in 41% yield. Both phenyldiphosphane and the dimeric complex [Cp*
Fe (µ-{PC Ph H } )].
2 2 5 3 2 2
2
7
,41
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An analogous reaction with Ph
3
SnCl in THF produced the
P–Sn functionalized complex 8 (Scheme 2e), but the reaction
3
1
1
was unselective. According to
P{ H} NMR integration
complex 8 is only present in a low amount (26% of the total P
content) in the reaction mixture after stirring for 17 h at room
temperature. Several attempts to isolate it as a pure compound
were not successful due to its low stability. Diphospinine
[
Cp* Fe (μ-{PC Ph H } )] and hexaphenyldistannane were
2
2
5
3
2 2
3
1
1
119
1
identified as decomposition products by P{ H} and Sn{ H}
NMR, suggesting decomposition by a radical pathway.
Crystallographic characterization of exo-3, endo-3, and 4–7
Single-crystal X-ray structure determinations of exo-3, endo-3
5
5
and 4–7 (Fig. 4 and Table 1) revealed η -Cp* and η -phospha-
cyclohexadienyl ligands. As a consequence, the phosphacyclo-
hexadienyl units are not planar. The P atom points away from
iron in complexes 4–6, and the heterocycle is folded along the
C1–C5 axis. The dihedral angles between the carbocyclic mean
plane and the plane defined by C1/P1/C5 (39.4° for 4, 37.0° for
5
Scheme 2 Synthesis of novel η -phosphacyclohexadienyl complexes
–8; reagents and by-products: (a) +MeI/−KI, −[18]crown-6; (b)
Me SiCl/−KCl, −[18]crown-6; (c) +Ph PCl/−KCl, −[18]crown-6; (d)
chlorocatecholborane/−KCl, −[18]crown-6; (e) +Ph SnCl/−KCl,
4
5
[
) are close to the values in the related complexes 2 (38.2°) and
Cp*Fe(1-Cp*-PC Ph )] (39.7°) previously reported by us
(Fig. 2c, vide supra). The corresponding fold angle for 6
27.2°) is over 10° shorter and similar to that of [Cp*Fe(1-
+
+
−
3
2
5
3 2
H
3
7
[18]crown-6; isolated yields of the products are given in parentheses.
(
7
2 5 3 2
NMe -PC Ph H )] (28.1°, vide supra).
The 2-substituted phosphacyclohexadienyl complex 7 was
In exo-3, endo-3 and 7 the C1 atom adjacent to phosphorus
is bent away from the iron center; consequently the six-mem-
bered phosphinine ring is folded along the P1–C2 axis. The
corresponding plane to plane angles are larger than in 4–6
obtained as bright orange crystals by a similar reaction with
one equiv. of chlorocatecholborane (Scheme 2d). Compound 7
is moderately soluble in n-pentane and n-hexane, but dissolves
well in more polar solvents such as diethyl ether, toluene and
THF. P{ H} NMR monitoring ([D
100 °C revealed a signal at −26 ppm, which we tentatively
assign to the intermediate [Cp*Fe(1-BCat-PC Ph H )] (7-P,
(
60.6° for endo-3, 63.4° for exo-3 and 59.7° for 7). Complexes
3
1
1
8
]THF, see ESI, Fig. S23†) at
endo-3, exo-3 and 7 are rare phosphinine-type complexes,
5
−
4
which show η -coordination through a C P-unit. To the best of
5
3
2
our knowledge, the sole example comprising the same struc-
8
Scheme 3) containing a direct P–B bond. The signal is broad,
tural motif is endo-F (Fig. 2b, vide supra).
3
1
10/11
5
therefore the P–
B coupling constant cannot be precisely
The C–C distances of the η -coordinated C
5
and C
4
P-units
determined, but the characteristic 1 : 1 : 1 : 1 quartet structure
is clearly visible. The resonance of intermediate 7–B decreased
upon warming and completely disappeared at −40 °C. The
signal of 7 simultaneously appeared above −60 °C.
The P{ H} NMR spectrum recorded at room temperature
shows the presence of 7, the diphoshinine complex
exo-3, endo-3 and 4–7 (Table 1) are in between typical single
1
9
and double bond distances. Similar bond lengths were
6
observed for the η -coordinated phosphinine ring in complex
7
G. In addition, it is noteworthy that the C1–C2 distances of
3
1
1
endo-3 (1.521(2) Å), exo-3 (1.540(3) Å) and 7 (1.526(2) Å) corres-
2
0
pond to the value for a normal single bond. The P–C bond
lengths in 4–6 are typical for single bonds and similar to those
[
Cp* Fe (µ-{PC Ph H } )], the hydrophosphinine complex
2 2 5 3 2 2
4
,7
endo-3 and a small signal for an unidentified by-product
singlet at −50 ppm). The observation of this mixture shows
in B and H (Fig. 2, vide supra). The P–C bond lengths are dis-
(
tinct in endo-3, exo-3 and 7: the P1–C1 distances (1.891(2)–
that other processes than borylation may also occur, explain-
ing the modest isolated yield (26%).
20
1.851(2) Å) are in the typical range for P–C single bonds,
whereas the P1–C5 (1.792(2)–1.785(2) Å) bonds are shorter and
6
7
close to those found in the η -coordinated ring in G.
While the P1–Si1 bond length (2.270(2) Å) of 5 is typical for
1
9
a P–Si single bond, the P1–P2 bond (2.3062(7) Å) of 6 is elon-
gated compared to that in unsymmetrically-substituted dipho-
sphanes such as 9-diphenylphosphanyl-9-phosphabicyclo-
2
1
[
3.3.1]nonane (2.229(1) Å). An analogous observation was
made by Gudat et al. for P-phosphanyldiazaphospholenes, e.g.
2
-diphenylphosphanyl-1,3-dimesityldiazaphospholene, which
22
displays a similarly elongated P–P bond (2.334(1) Å).
Scheme 3 Presumed formation of 2-substituted 7 via the 1-substituted
intermediate 7-P; reagents and by-products: (a) +chlorocatecholbor-
ane/−KCl, −[18]crown-6.
In 7, the B1–C1 distance (1.563(2) Å) is in the range of
normal boron–carbon single bonds (1.597 Å). The boron
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Fig. 4 Solid-state molecular structures of complexes endo-3, exo-3 and 4–7. Ellipsoids are drawn at the 40% probability level; H atoms except H1
in endo-3 and exo-3, and [18]crown-6 in 7 are omitted for clarity, key bond lengths (Å) and angles (°) for 4: P1–C6 1.853(2), C1–P1–C6 103.94(7),
C5–P1–C6 102.72(7); for 5: P1–Si1 2.270(2), C1–P1–Si1 104.4(1), C5–P1–Si1 106.6(1); for 6: P1–P2 2.3062(7), C1–P1–P2 107.54(7), C5–P1–P2
1
05.82(7); for 7: C1–B1 1.563(2), B1–O1 1.385(2), B1–O2 1.388(2), P1–C1–B1 104.11(1), C2–C1–B1 113.0(1), O1–B1–C1 123.3(1), O2–B1–C1 125.5(1),
O1–B1–O2 111.2(1); see Table 1 for additional structural data.
Table 1 Selected bond lengths (Å) and angles (°) of the structures of compounds endo-3, exo-3 and 4–7
endo-3
exo-3
4
5
6
7
Fe1–P1
Fe1–C1
Fe1–C2
Fe1–C3
Fe1–C4
Fe1–C5
Fe1–Cp*(c)
P1–C1
C1–C2
C2–C3
C3–C4
C4–C5
2.3125(5)
2.881(2)
2.103(2)
2.059(1)
2.090(2)
2.098(2)
1.700(1)
1.851(2)
1.521(2)
1.459(2)
1.433(2)
1.419(2)
1.786(2)
98.3(1)
2.2946(6)
2.933(2)
2.133(2)
2.061(2)
2.085(2)
2.096(2)
1.703(1)
1.870(2)
1.540(3)
1.456(3)
1.421(3)
1.427(3)
1.792(2)
96.0(1)
2.8786(4)
2.160(1)
2.059(1)
2.091(1)
2.049(1)
2.150(1)
1.698(1)
1.818(1)
1.418(2)
1.422(2)
1.428(2)
1.423(2)
1.809(1)
119.5(1)
93.46(6)
2.871(1)
2.168(4)
2.052(4)
2.088(4)
2.050(4)
2.151(4)
1.699(2)
1.828(5)
1.404(6)
1.435(6)
1.430(6)
1.429(6)
1.819(4)
120.9(3)
93.5(2)
2.7785(5)
2.170(2)
2.048(2)
2.086(2)
2.057(2)
2.161(2)
1.693(1)
1.795(2)
1.414(3)
1.428(3)
1.423(3)
1.414(3)
1.801(2)
123.6(2)
95.07(8)
2.2783(4)
2.901(2)
2.087(2)
2.061(2)
2.092(2)
2.096(2)
1.701(1)
1.891(2)
1.526(2)
1.432(2)
1.4272)
a
1.416(2)
1.785(2)
95.50(9)
99.20(7)
P1–C5
P1–C1–C2
C1–P1–C5
98.86(7)
98.35(9)
a
Cp*(c) = centroid of the cyclopentadienyl ring.
centre comprises a trigonal planar environment (angular sum complexes where a P–C–B(OMe) unit coordinates to chro-
2
2
0
24
=
360°). It seems noteworthy that Mathey and co-workers syn- mium or iron via the P atom. An example is the compound
thesized related phosphinine borates, e.g. Li[2-BEt -PC H ] by [FeH(CO) (SiPh ){Me PCH B(OMe) }]. Different from these
3
5
4
3
3
2
2
2
2
3
reaction of 2-bromophosphinines with two equiv. LiBHEt3.
These anionic molecules contain a tetrahedral boron atom in of 7 acts as a π-ligand to iron through the planar C
σ-coordinated complexes, the phosphacyclohexadienyl ligand
P-unit.
4
the 2-position; they can be converted into 2-ethylated Thus, the phosphorus lone pair remains uncoordinated and
phosphinines by reaction with iodine. Braunschweig et al. pre- should be able to act as a Lewis base. The trivalent boron
pared a series of (dimethoxyborylmethyl)dimethylphosphane center might function as a Lewis acid in related complexes
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1
13
1
31
1
Table 2 Characteristic H, C{ H} and P{ H} NMR data of complexes endo-3, exo-3 and 4–7; atom labelling according to Fig. 3
3
1
1
1
13
1
P{ H} NMR
H NMR
(CH
C{ H} NMR
3
1
1
Complex
P1 (ppm)
C
5
3
)
5
(ppm)
C2–H, C4–H (ppm)
JHP (Hz)
C1, C5 (ppm)
JC1P, JC5P (Hz)
a
endo-3
exo-3
4
5
6
7
−136.3 (s)
−160.7 (s)
−57.4 (s)
−77.7 (s)
−38.8 (d)
−126.7 (s)
1.36 (s)
1.30 (s)
1.02 (s)
1.02 (s)
0.98 (s)
1.34 (s)
2.98 (dd), 7.20–7.24 (m)
2.44 (s), 7.13–7.40 (m)
2.4
n.d.
2.6
2.5
2.9
34.7 (d), 95.2 (d)
31.7 (d), 97.7 (d)
41.1 (d)
29.2 (d)
41.0 (dd)
23.2, 69.9
19.7, 67.5
1.1
0.9
12.5
b
6.07 (d)
6.21 (d)
6.02 (d)
c
3.51 (s), 6.03–6.05 (m)
n.d.
n.d., 95.2 (d)
n.d., 74.5
a
b
c
Overlapping with meta-H of C5-Ph. Overlapping with Ar-H of C1-Ph and meta/para-H of C3-Ph/C5-Ph. Overlapping with ortho-H of C1-Ph.
n.d. = not detected.
with less strongly electron-donating substituents at boron,
The UV/vis spectra of endo-3–7 were recorded in n-hexane.
enabling the formation of a new frustrated Lewis pair type system. The spectra of 2-H-substituted endo-3 and exo-3 are similar
and display a weak shoulder at 450 nm; three stronger bands
are found in the UV range (endo-3 220, 260 and 320 nm; exo-3
NMR and UV-Vis spectroscopic characterization
230, 275 and 325 nm). The spectrum of the structurally related
1
13
1
31
1
Table 2 summarizes H, C{ H} and P{ H} NMR data of complex 7 is analogous, showing slightly bathochromically
]THF. The P NMR shifted bands at 260, 290sh, 360sh and 460sh nm. The UV/vis
signals of exo-3 (−160.7 ppm, J not detected) and endo-3 spectra of the 1-substituted species 4–6 are distinct from those
31
endo-3, exo-3 and 4–7 recorded in [D
8
2
PH
2
(
−136.3 ppm, JPH = 15.2 Hz) are slightly downfield shifted in of the aforementioned complexes and feature two visible
comparison with those of the cyclopentadienyl analogues exo-F absorptions each with moderate intensities in the ranges λmax
−173.0 ppm) and endo-F (−150.1 ppm) synthesised by Nief and 550–580 nm and λmax = 480–580 nm, respectively. Similar
=
(
8
1
13
Fischer, which otherwise feature similar H and C NMR shifts spectra were observed for other complexes of this type (type H,
7
of the phosphacyclohexadienyl units as their Cp*-substituted Fig. 2c). Previous TD-DFT calculations indicated that these
equivalents. Notably, the simple change of the configuration of a bands predominantly arise from excitations from filled metal-
7
carbon atom of the phosphinine ring causes an upfield shift of centered MOs into the ligand-based unoccupied MOs (MLCT).
31
the P NMR doublet of exo-3 by almost 25 ppm with respect to
endo-3. The aliphatic hydrogen atom of the phosphacyclohexa-
dienyl ring resonates at 2.76 ppm for endo-3 and at 1.66 ppm for Conclusions
exo-3. The spectrum of exo-3 thus displays a pronounced upfield
The reaction of the anionic phosphinine complex 1 with
diverse electrophiles represents a novel and straightforward
synthetic pathway to phosphacyclohexadienyl iron complexes.
Protonation of 1 using HCl(OEt ) initially affords the 1-substi-
tuted complex 2 at low temperature, which appears to undergo
shift for the exo-hydrogen atom comparable to that observed for
5
25
the related cyclohexadienyl complex [CpFe(η -C
6 7
H )].
The spectra of 1-substituted 4–6 overall resemble those of
7
1
related complexes of type H (Fig. 2c). Characteristic H NMR
2
2
features of 4 and 5 are the doublets at −0.13 ppm ( JHP = 5.5
an acid catalyzed rearrangement and converts to a mixture of
isomers, including the 2-H-substituted compounds endo-3 and
exo-3. The latter complexes were conveniently isolated in good
yields from the reaction of 1 with isopropyl chloride. An ana-
logous 2-substitued complex 7 formed in the reaction with
chlorocatecholborane. Similar to the hydrophosphinine com-
plexes, an initial formation of a phosphorus-substituted complex
followed by a subsequent 1,2-shift of the substituent was
Hz) for the methyl group of 4 and the Me
3
Si group of 5
3
31
1
(
−0.41 ppm, J = 3.4 Hz). The P{ H} NMR signal of the tri-
HP
methylsilyl-substituted complex
5 is upfield shifted by
2
0.3 ppm compared to the methyl-substituted analogue 4. Two
3
1
1
P{ H} NMR doublets are observed for 6 at 12.8 and
1
−
38.8 ppm with a large JPP coupling constant (293 Hz) in the
2
6
typical range for a covalent P–P single bond. The signal at
1
2.8 ppm is assigned to the PPh group, because it splits into
2
3
1
3
3 2 3
observed. Using MeI, Me SiCl, Ph PhCl and Ph SnCl, 1-substi-
a doublet of quintets in the P NMR spectrum ( JPH = 6.5 Hz).
Complex 7, which features a 2-substituted phosphacyclohexa-
tuted complexes 4–6 and 8 were obtained. Thus, HCl(OEt ), iso-
2
31
1
propyl chloride and chlorocatecholborane result in products
dienyl moiety, gives rise to a similar high-field P{ H} NMR
singlet (−126.7 ppm) as endo-3 (−136.3 ppm); the H NMR data
1
substituted at the 2-carbon atom, whereas MeI, Me SiCl,
3
Ph SnCl and Ph PhCl provide phosphorus-substituted products.
(Table 2) are also similar in agreement with the similar
3
2
An extensive family of related compounds could become
accessible via this route. In addition, the reactivity and possible
catalytic activity of the new complexes presented here needs to
be examined, where the unusually long P–P bond in 6 and the
FLP type motif in 7 will be of particular interest. Investigations
in these directions are underway in our laboratory.
structures.§
1
3
1
3
§
The C{ H} NMR resonance for sp -hybridized carbon atom of 7 attached to
31
13
10/11
phosphorus and boron was not observed. Coupling in the P– C–
B spin
11
system and the quadrupole relaxation mechanism of the B nucleus presumably
42
lead to substantial broadening of this signal.
8880 | Dalton Trans., 2016, 45, 8875–8884
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Dalton Transactions
Paper
4
2,6
6
3
C –Ph), 7.80 (d, 2H, C –H of C –Ph), 7.93 (d, JHH = 7.8 Hz, 2H,
Experimental
General considerations
2,6
4
13
1
C
–H of C –Ph). C{ H} NMR (100.61 MHz, 300 K, [D ]THF):
8
3
3
δ = 10.0 (d, JCP = 3.4 Hz, C
5
(CH
)
3 5
), 26.3 (s, C –H of TPP), 34.7
1
2
2
All experiments were performed under an atmosphere of dry (d, JCP = 23.2 Hz, C of TPP), 87.9 (s, C
5
(CH
)
3 5
), 88.8 (d, JCP
=
5
4
1
argon, by using standard Schlenk and glovebox techniques. 7.9 Hz, C –H of TPP), 91.8 (s, C of TPP), 95.2 (d, J = 69.9 Hz,
CP
6
4
2
3
2
Solvents were purified, dried, and degassed with an MBraun C of TPP), 125.2 (s, C –H of C –Ph), 126.3 (d, JCP = 3.5 Hz, C –
2
5
4
6
SPS800 solvent purification system. NMR spectra were H of C –Ph), 127.1 (d, JCP = 1.1 Hz, C –H of C –Ph), 127.7 (s,
4
4
2,6
4
2,6
recorded on Bruker Avance 300 and Avance 400 spectrometers C –H of C –Ph), 127.5 (s, C –H of C –Ph), 127.9 (s, C –H of
4
3,5
2
4
3,5
at 300 K and internally referenced to residual solvent C –Ph), 128.1 (s, C –H of C –Ph), 128.6 (d, JCP = 1.0 Hz, C
–
1
13
6
3,5
4
1
4
resonances. The assignment of the H and C NMR signals H of C –Ph), 129.0 (s, C –H of C –Ph), 141.8 (s, C of C –Ph),
was confirmed by two-dimensional (COSY, HSQC, and 143.8 (d, J = 17.8 Hz, C of C –Ph), 147.1 (d, J = 1.8 Hz, C
HMBC) experiments. Melting points were measured on of C –Ph). P{ H} NMR (161.98 MHz, 300 K, [D
2
1
6
2
1
CP
31
CP
2
1
8
]THF): δ =
3
1
samples in sealed capillaries on a Stuart SMP10 melting point –136.3 (s). P NMR (161.98 MHz, 300 K, [D
8
]THF): δ = –136.3
apparatus. UV/vis spectra were recorded on a Varian Cary 50 (d, J = 15.3 Hz). Elemental analysis calcd for C H FeP (M
w
2
PH
33 33
spectrometer. Elemental analyses were determined by the = 516.45 g mol− ) C 76.75, H 6.44; found C 76.11, H 6.55.
1
analytical department of Regensburg University. The starting exo-3.
4
7
material [K([18]crown-6)(thf) ][Cp*Fe(η -PC Ph H )] (1) was
2
5
3
2
2
prepared according to literature procedures. HCl(Et O) solu-
tion, methyl iodide, trimethylsilyl chloride, chlorocatecholborane
and chlorodiphenylphosphane were purchased from Sigma-
Aldrich and TCI and were used as received.
5 3 2
[Cp*Fe(2-endo-H-PC Ph H )] (endo-3) and [Cp*Fe(2-exo-
H-PC Ph H )] (exo-3). A solution of isopropyl chloride in THF
5
3
2
M.p. 177 °C. UV/vis: (n-hexane, λmax nm−1, εmax/L mol−1 cm ):
−1
−
1
(1.0 mL, c = 0.108 mol L ) was added to a dark orange solu-
1
230sh (72 000), 275 (59 000), 325sh (17 000), 450sh (1100). H
tion of 1 (104 mg, 0.108 mmol) in THF (5 mL). The solution
was stirred at room temperature for 24 hours. The resulting
dark orange brown mixture was subjected to column chromato-
graphy (silica gel, 22 × 1 cm, n-hexane/toluene gradient, 100/1
to 5/1). Two bright orange bands were obtained: exo-3 was
8
NMR (400.13 MHz, 300 K, [D ]THF): δ = 1.30 (s, 15H,
2
3
C (CH ) ), 1.66 (s br, 1H, C –H of TPP), 2.44 (s br, 1H, C –H of
5
3 5
2
5
TPP), 7.13–7.40 (overlapping m, 12H, Ar–H of C –Ph + C –H of
3
,4,5
4
3,4,5
6
3
TPP + C
–H of C –Ph + C
–H of C –Ph), 7.86 (d, JHH = 7.9
2
,6
4
3
2,6
Hz, 2H, C –H of C –Ph), 7.90 (d, J = 7.9 Hz, 2H, C –H of
C –Ph). C{ H} NMR (100.61 MHz, 300 K, [D ]THF): δ = 9.9 (d,
8
) ), 21.4 (d, JCP = 5.1 Hz, C –H of TPP),
3 5
1.7 (d, J = 19.7 Hz, C of TPP), 86.9 (d, J = 7.3 Hz, C –H
of TPP), 88.1 (s, C (CH ) ), 92.3 (d, JCP = 1.8 Hz, C of TPP),
5 3 5
7.7 (d, JCP = 67.5 Hz, C of TPP), 125.9, 127.2, 127.3, 127.4,
27.5, 127.6, 127.7, 128.7, 128.9, 129.0 (C
of C –Ph), 140.8 (s, C of C –Ph),
43.6 (d, JCP = 16.7 Hz, C of C –Ph), 145.9 (d, JCP = 12.9 Hz,
C of C –Ph). P{ H} NMR (161.98 MHz, 300 K, [D ]THF): δ =
160.7 (s). P NMR (161.98 MHz, 300 K, [D
HH
eluted first (R
ping with endo-3, which followed immediately (R
f
(n–hexane/toluene, 5/1) = 0.42), slightly overlap-
(n-hexane/
6
13
1
f
3
2
3
J
CP = 2.8 Hz, C
5
(CH
toluene, 5/1) = 0.32). Removal of the solvent gave exo-3 and
endo-3 as pure bright orange solids. Yield of exo-3: 14 mg
1
2
2
5
3
CP
CP
3
4
(25%), yield of endo-3: 23 mg (41%), total including mixed frac-
1
6
9
1
C
tions: 45 mg (80%). X-ray quality crystals formed upon storage
of concentrated n-hexane solutions at room temperature for
three days. Variable elemental analyses were obtained for exo-3
and endo-3. Traces of silica gel can be removed by taking up the
product in n-hexane, filtration and removal of the solvent.
endo-3.
2
,3,4,5,6
2
of C –Ph,
2
,3,4,5,6
4
2,3,4,5,6
6
1
4
of C –Ph C
2
1
6
2
1
1
2
31
1
8
3
1
−
8
]THF): δ = −160.7
(
s br). Elemental analysis calcd for C H FeP (M = 516.45 g
3
3
33
w
−
1
mol ) C 76.75, H 6.44; found C 77.15, H 6.50.
Cp*Fe(1-Me-PC Ph )] (4).
[
5
3 2
H
M.p. 196 °C. UV/vis: (n-hexane, λmax/nm, εmax/L mol− cm ):
2
1
−1
1
20sh (37 000), 260 (29 600), 320sh (9300), 450sh (670).
H
NMR (400.13 MHz, 300 K, [D ]THF): δ = 1.36 (s, 15H, A solution of methyl iodide in THF (1 mL, c = 0.106 mol L−
1
)
8
2
3
2
C
5
(CH
3 5
) ), 2.76 (dd, JHP = 15.2 Hz, JHH = 8.1 Hz, 1H, C –H of was added to a dark orange solution of 1 (102 mg,
TPP), 2.98 (dd, JHP = 2.4 Hz, JHH = 8.1 Hz, 1H, C –H of TPP), 0.106 mmol) in THF (5 mL) at room temperature. The reaction
–H of C –Ph), 6.90–6.94 (m, 2H, C –H mixture turned burgundy red immediately, and was stirred for
of C –Ph), 7.16 (t, JHH = 7.2 Hz, 1H, C –H of C –Ph), 7.20–7.24 four hours at room temperature. After removing the solvent
3
3
3
2
,4,6
2
3,5
6
.77–6.81 (m, 3H, C
2
3
4
6
3,5
6
5
(
m, 3H, C –H of C –Ph overlapping with C –H of TPP), 7.31 (t, in vacuo, the remaining dark red residue was extracted with
3
4
4
3,5
JHH = 7.3 Hz, 1H, C –H of C –Ph), 7.37–7.42 (m, 2H, C –H of n-hexane (10 × 1 mL). The burgundy red extracts were com-
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Dalton Transactions
2
1
2,6
29
bined and the solution was concentrated to 5 mL. Dark red 146.5 (d,
JCP = 24.2 Hz, C of C –Ph). Si DEPT NMR
1
31
1
crystals of 4 formed during storage at −30 °C for three days. (79.49 MHz, 300 K, [D ]THF): δ = −3.3 (d, J = 62.4 Hz). P{ H}
8
SiP
−
1
29
Yield: 23 mg (41%). M.p. 239 °C. UV/vis: (n-hexane, λmax nm
,
NMR (161.98 MHz, 300 K, [D
JPSi = 62.1 Hz). P NMR (161.98 MHz, 300 K, [D ]THF): δ =
NMR (400.13 MHz, 300 K, [D ]THF): δ = −0.13 (d, J = 5.5 −77.7 (s, br). Elemental analysis calcd for C H FePSi (M
8
]THF): δ = −77.7 (s, Si-satellites:
−
1
−1
−1
1
1
31
ε
max
L
mol cm ): 380sh (3150), 480 (1440), 550 (1000). H
8
2
=
w
8
HP
36 41
3
−1
Hz, 3H, P–CH
2
7
3
), 1.02 (s, 15H, C
5
(CH
3
)
5
), 6.07 (d, JHP = 2.6 Hz, 588.63 g mol ) C 73.46, H 7.02; found C 73.81, H 6.97.
3
,5
3
4
2,6
H, C –H of TPP), 7.12 (t, JHH = 7.3 Hz, 2H, C –H of C –Ph),
.27–7.31 (m, 4H, C –H of C –Ph), 7.46 (t, J = 7.3 Hz, 1H,
C –H of C –Ph), 7.54–7.58 (m, 2H, C –H of C –Ph), 8.11–8.13
m, 4H, C –H of C –Ph), 8.32 (d, JHH = 7.7 Hz, 2H, C –H of
C –Ph). C{ H} NMR (100.61 MHz, 300 K, [D ]THF): δ = 8.9 (s,
5 3 5 3
C (CH ) ), 18.2 (d, JCP = 39.0 Hz, P–CH ), 41.1 (d, JCP = 1.1
Hz, C of TPP), 79.1 (d, JCP = 7.3 Hz, C –H of TPP), 85.3 (s,
C (CH ) ), 95.9 (d, J = 2.4 Hz, C of TPP), 124.7 (d, J = 2.8
Hz, C –H of C –Ph), 128.1 (C –H of C –Ph overlapping with
–H of C –Ph), 128.7 (s, C –H of C –Ph), 128.8 (d, JCP =
9.5 Hz, C –H of C –Ph), 129.4 (s, C –H of C –Ph), 141.6
CP = 25.2 Hz, C of C –Ph).
P{ H} NMR (161.98 MHz, 300 K, [D ]THF): δ = –57.4 (s).
2 5 3 2
[Cp*Fe(1-PPh -PC Ph H )] (6).
3
,5
2,6
3
HH
4
4
4
3,5
2
,6
2,6
3
2,6
(
4
13
1
8
1
1
2
,6
2
3,5
3
4
5
5
3 5
4
CP
CP
2,6
4
4
A solution of chlorodiphenylphosphane (35 mg, 0.159 mmol)
in THF (5 mL) at −95 °C was added dropwise to a dark orange
solution of 1 (150 mg, 0.156 mmol) in THF (10 mL) at −95 °C.
The reaction mixture turned deep red to violet and was slowly
warmed to room temperature. The solvent was removed
in vacuo after stirring at room temperature for 16 h. The
remaining residue was extracted with n-pentane (8 × 1 mL).
The extracted fractions were combined and concentrated to
mL. 6 was isolated as dark violet crystals after storage at
30 °C for three days. Yield: 48 mg (38%). M.p. 192 °C. UV/vis:
n-hexane, λmax nm , εmax
95 (30 800), 485 (2400), 550 (1900). H NMR (400.13 MHz,
2
,6
4
3,5
2,6
3
C
1
2
,6
2,6
3,5
4
1
4
2
1
2,6
(
s, C of C –Ph), 145.5 (d,
J
3
1
1
8
3
1
P NMR (161.98 MHz, 300 K, [D ]THF): δ = –57.4 (s, br).
8
= 530.47 g mol−
1
Elemental analysis calcd for C34
C 76.98, H 6.65; found C 77.22, H 6.40.
Cp*Fe(1-Me Si-PC Ph H )] (5).
H
35FeP (M
w
)
4
−
(
2
3
[
3
5
3
2
−
1
−1
−1
−1
L
mol cm ): 240sh (42 000),
1
3
00 K, [D ]THF): δ = 0.98 (s, 15H, C (CH ) ), 6.02 (d, J = 2.9
8
5
3 5
HP
3
3,4,5
Hz, 2H, C –H of TPP), 6.84–6.93 (m, 6H, C
–H of PPh2),
2
,6
3
6
2
.96–7.00 (m, 4H, C –H of PPh ), 7.10 (t, JHH = 7.2 Hz, 2H,
4
2,6
3,5
2,6
C –H of C –Ph), 7.21–7.25 (m, 4H, C –H of C –Ph), 7.47 (t,
3
4
4
3,5
J
= 7.2 Hz, 1H, C –H of C –Ph), 7.52–7.56 (m, 2H, C –H of
C –Ph), 7.99–8.02 (m, 4H, C –H of C –Ph), 8.13 (d, J
.8 Hz, 2H, C –H of C –Ph). C{ H} NMR (100.61 MHz,
00 K, [D ]THF): δ = 8.79 (s, C (CH ) ), 41.0 (dd, J = 12.5 Hz,
8 5 3 5 CP
CP = 10.6 Hz, C of TPP), 80.9 (dd, JCP = 12.6 Hz, JCP = 10.5
Hz, C –H of TPP), 85.8 (s, C (CH ) ), 97.3 (d, J = 2.2 Hz, C
of TPP), 125.0 (d, J = 3.3 Hz, C –H of C –Ph), 127.4 (s, C –
H of PPh ), 128.0 (d, J = 6.0 Hz, C of PPh ), 128.1 (s, C –H
A solution of trimethylsilyl chloride in toluene (0.9 mL, c =
0
HH
4
2,6
2,6
3
.152 mol L− ) was added to a dark orange solution of 1
1
HH
=
2
,6
4
13
1
7
(132 mg, 0.137 mmol) in THF (7 mL) and stirred at room temp-
1
3
erature for 16 h. The resulting dark greenish brown mixture
was dried in vacuo, and the residue was extracted with
n-pentane (16 × 0.5 mL). The fractions were combined and
dried in vacuo. [18]crown-6 was sublimed at 60 °C and <1.0 ×
2
2,6
2
3
J
3
3
4
5
3 5
4
CP
5
2,6
4
CP
3
3,5
4
−
3
1
0
mbar. The remaining residue was dissolved in n–hexane
2
CP
2,6
2
4
4
3,5
2,6
of C –Ph), 128.4 (s, C –H of C –Ph), 128.6 (s, C –H of C
Ph), 129.1 (s, C –H of C –Ph), 129.2 (d, J = 18.1 Hz, C –H
of C –Ph), 134.7 (dd, JCP = 17.2 Hz, JCP = 4.1 Hz, C –H of
–
(8 mL). The greenish black solution was filtered and concen-
3
,5
4
3
2
trated to 5 mL. 5 was isolated as dark green to black crystals
after storage at −30 °C for three days. Yield: 48 mg (59%).
CP
2
,6
2
3
2,6
1
2
1
−1
−1
−1
−1
PPh ), 138.7 (dd, JCP = 25.5 Hz, JCP = 6.9 Hz, C of PPh ),
2 2
M.p. 213 °C. UV/vis: (n-hexane, λmax nm , εmax
L
mol cm ):
1
4
2
1
2,6
1
141.0 (s, C of C –Ph), 144.9 (d, J = 24.5 Hz, C of C –Ph).
CP
2
50 (36 300), 300 (26 000), 500 (2300), 580 (2100). H NMR
3
1
1
1
3
P{ H} NMR (161.98 MHz, 300 K, [D ]THF): δ = 12.8 (d, J
293 Hz, PPh ), −38.8 (d, JPP = 293 Hz, P of TPP). P NMR
(161.98 MHz, 300 K, [D ]THF): δ = 12.8 (dquint, J = 293 Hz,
JPH = 6.5 Hz, PPh ), −38.8 (d, J = 293 Hz, P of TPP). Elemen-
tal analysis calcd for C H FeP (Mw = 700.62 g mol )
C 77.14, H 6.04; found C 77.55, H 6.36.
[Cp*Fe(2-BCat-PC Ph H )] (7).
PP
=
(400.13 MHz, 300 K, [D ]THF): δ = −0.41 (d, J = 3.4 Hz, 9H,
8
8
PH
1
31
3
P–Si(CH
C
)
3 3
), 1.02 (s, 15H, C
–H of TPP), 7.10 (t,
5
(CH
3
)
5
), 6.21 (d, JPH = 2.5 Hz, 2H,
2
1
3,5
3
4
2,6
J
HH = 7.2 Hz, 2H, C –H of C –Ph),
8
PP
3
1
3
,5
2,6
3
7
.22–7.27 (m, 4H, C –H of C –Ph), 7.47 (t, J = 7.3 Hz, 1H,
2
PP
HH
4
−
1
4
4
3,5
C –H of C –Ph), 7.56–7.60 (m, 2H, C –H of C –Ph), 8.08–8.11
45 42 2
2
,6
2,6
3
2,6
(m, 4H, C –H of C –Ph), 8.34 (d, JHH = 7.8 Hz, 2H, C –H of
4
13
1
C –Ph). C{ H} NMR (100.61 MHz, 300 K, [D ]THF): δ = −0.9
5
3
2
8
2
1
3 3 5 3 5
(d, JCP = 8.5 Hz, P–Si(CH ) ), 8.8 (s, C (CH ) ), 29.2 (d, JCP = 0.9
2,6
2
3,5
Hz, C of TPP), 82.2 (d, JCP = 8.3 Hz, C –H of TPP), 85.7 (s,
C (CH ) ), 97.9 (d, J = 1.2 Hz, C of TPP), 124.6 (d, J = 3.1
Hz, C –H of C –Ph), 127.9 (s, C –H of C –Ph), 128.3 (s, C –H
of C –Ph), 128.7 (s, C –H of C –Ph and d, JCP = 19.4 Hz, C
3
4
5
5
3 5
4
CP
CP
2,6
4
4
2,6
4
3,5
2,6
3
2,6
–
2
,6
3,5
4
1
4
H of C –Ph), 129.5 (s, C –H of C –Ph), 142.5 (s, C of C –Ph),
8882 | Dalton Trans., 2016, 45, 8875–8884
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Paper
A solution of chlorocatecholborane (24 mg, 0.155 mmol) in
CCDC 1448678–1448684 contain the supplementary crystal-
THF (5 mL) was added to a dark orange solution of 1 (150 mg, lographic data for this paper.
0
.156 mmol) in THF (10 mL) at −35 °C. The mixture was
DFT calculations
stirred and warmed to room temperature overnight. All vola-
tiles were removed in vacuo and the dark orange-green residue
was washed with n–hexane (5 × 1 mL) and extracted with
diethyl ether (10 × 0.5 mL). The deep orange diethyl ether frac-
tions were combined and the major impurities including
The calculations on 2, endo-3 and exo-3 were performed using
3
1
the ORCA program package (version 3.0.2). The BP86 density
functional and the Ahlrichs def2-TZVP basis set were employed
3
2–36
37,38
for all atoms.
Ahlrichs Coulomb fitting basis for the TZVP basis for all atoms
TZV/J) and the atom-pair-wise dispersion correction to the
DFT energy with Becke-Johnson damping (d3bj) were
The RI approximation was used.
The
[18]crown-6 were crystallized by storage at room temperature
for five days. The deep orange mother liquor was decanted and
concentrated to 3 mL. Deep orange crystals of 7 formed during
storage at room temperature for two days. Yield: 25 mg (25%).
M.p. 196 °C (decomposition to a dark green solid). UV/vis:
(
3
9,40
applied.
The nature of the stationary points was verified by
numerical frequency analysis.
−
1
−1
−1
−1
(
n–hexane, λmax nm , εmax
L
mol cm ): 260 (15 000),
1
2
90sh (10 000), 360sh (1700), 460sh (300).
]THF): δ = 1.34 (s, 15H, C
H
NMR
(400.13 MHz, 300 K, [D
8
5
(CH
3
)
5
), 3.51
Acknowledgements
3
4
2
(s, 1H, C –H of TPP), 6.68–6.72 (m, 1H, C –H of C –Ph),
3
,5
2
6
3
.89–6.91 (m, 2H, C –H of C –Ph), 6.03–6.05 (overlapping m, Funding by the Deutsche Forschungsgemeinschaft is gratefully
H, C –H of C –Ph overlapping with C –H of TPP), 7.07–7.11 acknowledged.
2
,6
2
5
2
,5
4
(m, 2H, C –H of catecholboryl), 7.17–7.21 (m, 1H, C –H of
6
3,5
6
C –Ph), 7.23–7.26 (m, 2H, C –H of C –Ph), 7.28–7.30 (m, 2H,
C
3
,4
4
4
–H of catecholboryl), 7.32–7.36 (m, 1H, C –H of C –Ph),
Notes and references
3
,5
4
3
7
.44–7.48 (m, 2H, C –H of C –Ph), 7.85 (d, J = 7.9 Hz, 2H,
HH
2,6
2
,6
6
3
4
C
–H of C –Ph), 8.04 (d, JHH = 7.9 Hz, 2H, C –H of C –Ph).
1 C. Müller, L. E. E. Broeckx, I. de Krom and
J. J. M. Weemers, Eur. J. Inorg. Chem., 2013, 187–202.
2 M. Bruce, G. Meissner, M. Weber, J. Wiecko and C. Müller,
Eur. J. Inorg. Chem., 2014, 1719–1726.
3 G. Märkl and C. Martin, Angew. Chem., 1974, 86, 445–446.
4 G. Baum and W. Massa, Organometallics, 1985, 4, 1572–
1574.
5 A. Moores, N. Mézailles, L. Ricard and P. Le Floch, Organo-
metallics, 2005, 24, 508–513.
6 A. Moores, L. Ricard, P. Le Floch and N. Mézailles, Organo-
metallics, 2003, 22, 1960–1966.
7 B. Rezaei Rad, U. Chakraborty, B. Mühldorf, J. A. W. Sklorz,
M. Bodensteiner, C. Müller and R. Wolf, Organometallics,
2015, 34, 622–635.
8 F. Nief and J. Fischer, Organometallics, 1986, 5, 877–883.
9 M. Doux, N. Mézailles, L. Ricard and P. Le Floch, Organo-
metallics, 2003, 22, 4624–4626.
1
3
1
3
C{ H} NMR (100.61 MHz, 300 K, [D
8
]THF): δ = 9.7 (d, JCP
=
3
3
.2 Hz, C (CH ) ), 26.1 (s, C –H of TPP), 88.4 (s, C (CH ) ),
5
3 5
5
3 5
2
5
4
8
8.6 (d, JCP = 7.3 Hz, C –H of TPP), 90.9 (s, C of TPP), 95.2 (d,
CP = 74.5 Hz, C of TPP), 112.9 (s, C –H of catecholboryl),
1
6
3,4
J
2
,5
4
2
1
1
23.3 (s, C –H of catecholboryl), 124.3 (s, C –H of C –Ph),
27.3 (s, C –H of C –Ph overlapping with C of C –Ph), 127.4
2
,6
4
4
6
3
2,6
2
4
4
(d, JCP = 4.6 Hz, C of C –Ph), 127.6 (s, C –H of C –Ph), 127.7
3
,5
2
3
2,6
6
(s, C –H of C –Ph), 127.9 (d, J = 15.0 Hz, C of C –Ph),
CP
3,5
6
3,5
4
1
128.7 (s, C –H of C –Ph), 129.2 (s, C –H of C –Ph), 141.6 (s, C
4
2
1
6
1
of C –Ph),143.5 (d, JCP = 18.0 Hz, C of C –Ph), 147.8 (s, C of
C –Ph), 149.5 (s, C of catecholboryl), the signal for C of TPP
2
1,6
2
11
1
was not observed. B{ H} NMR (128.38 MHz, 300 K, [D
8
]THF):
]THF): δ = 34.3 (s
br). P{ H} NMR (161.98 MHz, 300 K, [D ]THF): δ = −126.7 (s).
11
δ = 34.3 (s br). B NMR (128.38 MHz, 300 K, [D
8
31
1
8
31
P NMR (161.98 MHz, 300 K, [D
8
]THF): δ = −126.7 (s br).
−1
Elemental analysis calcd for C39 36BFeO P (M = 634.34 g mol )
H
2 w
C 73.84, H 5.72; found C 73.45, H 5.73.
10 H. Lehmkuhl, J. Elsäßer, R. Benn, B. Gabor, A. Rufińska,
R. Goddard and C. Krüger, Z. Naturforsch., B: Anorg. Chem.
Org. Chem., 1985, 40, 171–181.
X-Ray crystallography
Crystals of endo-3, exo-3, 4, 5, and 8 suitable for X-ray diffrac- 11 B. Nuber and M. L. Ziegler, Acta Crystallogr. C: Cryst. Struct.
tion were obtained from n-hexane. Crystals of 6 were obtained Commun., 1987, 43, 59–61.
from diethyl ether. X-ray quality crystals of 7 were obtained 12 M. Doux, L. Ricard, P. Le Floch and Y. Jean, Organometal-
from concentrated diethyl ether solutions of the crude reaction lics, 2005, 24, 1608–1613.
mixture resulting in crystallization along with half a molecule 13 T. Arliguie, M. Doux, N. Mézailles, P. Thuéry, P. Le Floch
of [18]crown-6. The single crystal X-ray diffraction data were and M. Ephritikhine, Inorg. Chem., 2006, 45, 9907–9913.
recorded on an Agilent Technologies Gemini Ultra R diffracto- 14 M. Doux, P. Thuéry, M. Blug, L. Ricard, P. Le Floch,
meter (exo-3 and 5) and an Agilent Technologies SuperNova
endo-3, 4, and 6–8) with Cu K radiation (λ = 1.54184 Å). Semi-
T. Arliguie and N. Mézailles, Organometallics, 2007, 26,
5643–5653.
(
α
2
7
empirical multi-scan absorption corrections and analytical 15 T. Arliguie, M. Blug, P. Le Floch, N. Mézailles, P. Thuéry
28
ones were applied to the data. The structures were solved
and M. Ephritikhine, Organometallics, 2008, 27, 4158–4165.
2
9
2
with SHELXT
carried out with SHELXL.
and least-square refinements on F were 16 T. Arliguie, P. Thuéry, P. L. Floch, N. Mézailles and
3
0
M. Ephritikhine, Polyhedron, 2009, 28, 1578–1582.
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Paper
Dalton Transactions
1
1
1
2
2
7 A. Moores, N. Mézailles, L. Ricard, Y. Jean and P. le Floch, 29 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Adv., 2015,
Organometallics, 2004, 23, 2870–2875. 71, 3–8.
8 H. Lehmkuhl, R. Paul, C. Krüger, Y.-H. Tsay, R. Benn and 30 G. M. Sheldrick, Acta Crystallogr., Sect. A: Fundam. Crystal-
R. Mynott, Liebigs Ann. Chem., 1981, 1147–1161. logr., 2008, 64, 112–122.
9 P. Pyykkö and M. Atsumi, Chem. – Eur. J., 2009, 15, 12770– 31 F. Neese, Wiley Interdiscip. Rev.: Comput. Mol. Sci., 2012, 2,
2779. 73–78.
0 P. Pyykkö and M. Atsumi, Chem. – Eur. J., 2009, 15, 186– 32 A. Schäfer, H. Horn and R. Ahlrichs, J. Chem. Phys., 1992,
97. 97, 2571–2577.
1
1
1 D. L. Dodds, J. Floure, M. Garland, M. F. Haddow, 33 A. D. Becke, J. Chem. Phys., 1993, 98, 5648–5652.
T. R. Leonard, C. L. McMullin, A. G. Orpen and 34 A. D. Becke, J. Chem. Phys., 1993, 98, 1372–1377.
P. G. Pringle, Dalton Trans., 2011, 40, 7137–7146.
2 S. Burck, D. Gudat and M. Nieger, Angew. Chem., 2004, 116,
35 F. Weigend and R. Ahlrichs, Phys. Chem. Chem. Phys., 2005,
7, 3297–3305.
2
2
2
4
905–4908.
36 C. Lee, W. Yang and R. G. Parr, Phys. Rev. B: Condens.
Matter, 1988, 37, 785–789.
37 A. D. Becke, Phys. Rev. A, 1988, 38, 3098–3100.
3 D. Carmichael, P. L. Floch, H. G. Trauner and F. Mathey,
Chem. Commun., 1996, 971.
4 H. Braunschweig, R. Dirk and B. Ganter, J. Organomet. 38 J. P. Perdew, Phys. Rev. B: Condens. Matter, 1986, 33, 8822–
Chem., 1997, 545–546, 257–266.
8824.
2
2
5 S. D. Ittel, J. Organomet. Chem., 1980, 195, 331–335.
6 J. Emsley and D. Hall, The Chemistry of Phosphorus, Harper
39 S. Grimme, S. Ehrlich and L. Goerigk, J. Comput. Chem.,
2011, 32, 1456–1465.
&
Row Ltd, London, 1976.
40 S. Grimme, J. Antony, S. Ehrlich and H. Krieg, J. Chem.
Phys., 2010, 132, 154104.
2
2
7 (a) SCALE3ABS, CrysAlisPro, Aglient Technologies Inc.,
Oxford, UK, 2015; (b) G. M. Sheldrick, SADABS, Bruker AXS, 41 D. L. Dodds, M. F. Haddow, A. G. Orpen, P. G. Pringle
Madison, USA, 2007.
and G. Woodward, Organometallics, 2006, 25, 5937–
8 (a) R. C. Clark and J. S. Reid, Acta Crystallogr., Sect. A:
5945.
Fundam. Crystallogr., 1995, 51, 887–897; (b) CrysAlisPro, 42 R. A. Oliveira, R. O. Silva, G. A. Molander and
Agilent Technologies Inc., Oxford, UK, 2015.
P. H. Menezes, Magn. Reson. Chem., 2009, 47, 873–878.
8884 | Dalton Trans., 2016, 45, 8875–8884
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