Solid State Structure of cis-[W(CO)4(pip)(PPh3)]

Article abstract of DOI:10.1007/s10870-018-0743-1

The solid state structure of cis-[W(CO)₄(PPh₃)(pip)] (1) was determined by X-ray crystallography. cis-[W(CO)₄(PPh₃)(pip)] was synthesized by reaction of PPh₃ with cis-[W(CO)₄(pip)₂] and isolated as yellow crystals. Compound 1 crystalized in the monoclinic space group P2₁/c and was found to have a distorted octahedral geometry. The P–W–N angle was slightly more acute than expected, presumably due to an unusual N–H?π interaction. Graphical Abstract: The solid state structure of cis-[W(CO)₄(PPh₃)(pip)] (1) is described with an P–W–N angle slightly more acute than expected, presumably due to an N–H?π interaction. [Figure not available: see fulltext.].

Full text of DOI:10.1007/s10870-018-0743-1

Journal of Chemical Crystallography
https://doi.org/10.1007/s10870-018-0743-1
BRIEF COMMUNICATION
Solid State Structure of cis-[W(CO)4(pip)(PPh3)]
Jennifer L. Harkreader1 · Brian J. Frost1
Received: 26 July 2018 / Accepted: 10 October 2018
© Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
The solid state structure of cis-[W(CO)4(PPh3)(pip)] (1) was determined by X-ray crystallography. cis-[W(CO)4(PPh3)(pip)]
was synthesized by reaction of PPh3 with cis-[W(CO)4(pip)2] and isolated as yellow crystals. Compound 1 crystalized in the
monoclinic space group P21/c and was found to have a distorted octahedral geometry. The P–W–N angle was slightly more
acute than expected, presumably due to an unusual N–H⋯π interaction.
Graphical Abstract
The solid state structure of cis-[W(CO)4(PPh3)(pip)] (1) is described with an P–W–N angle slightly more acute than expected,
presumably due to an N–H⋯π interaction.
Keywords Tungsten carbonyl · Ligand substitution · Structure elucidation · Hydrogen bonding
Introduction
Electronic supplementary material The online version of this
The tetracarbonyl bispiperidine complexes, cis-
article (https://doi.org/10.1007/s10870-018-0743-1) contains
[M(CO)4(pip)2] (where pip = HNC5H10), of the group six
metals (tungsten, molybdenum, chromium) are important
precursors to cis-[M(CO)4(PR3)2] complexes [1, 2]. Ligand
substitution of the piperidine occurs, presumably, stepwise.
In the case of Mo the ligands substitution occurs cleanly
with conversion to [M(CO)4L2]. In the case of tungsten the
supplementary material, which is available to authorized users.
* Brian J. Frost
Frost@unr.edu
1
Department of Chemistry, University of Nevada,
89557 Reno, NV, USA
Vol.:(0123456789)
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Journal of Chemical Crystallography
Table 1 Crystal data and structure refinement for cis-[W(CO)4(pip)
(PPh3)] (1)
first substitution occurs in a facile manner at low tempera-
ture (~40 °C), substitution of the second piperidine requires
slightly more forcing (~60 °C) conditions [1, 2]. Few exam-
ples of the mixed phosphine–piperidine intermediate, cis-
[M(CO)4(pip)(PR3)], have been structurally characterized
with the vast majority molybdenum complexes [2–10].
1
Formula
fw
T (K)
C27H26NO4PW
643.31
100 (2)
λ, Å
0.71073
Monoclinic
P21/c
9.2746 (3)
16.0281 (6)
17.0827 (6)
90
Cryst syst
Space group
a (Å)
b (Å)
c (Å)
Experimental
All manipulations were done under inert atmosphere using
standard Schlenk techniques. Reagents were obtained from
commercial sources and used as received. Solvents were dis-
tilled from standard drying agents (Na/benzophone for THF,
hexanes; Mg/I2 for methanol) or purged with nitrogen and
dried with activated molecular sieves before use. Tetracar-
bonyl bispiperidine tungsten (0) was prepared as described
in the literature [1].
α (°)
β (°)
99.1430 (10)
90
2507.15 (15)
4
1.704
4.704
0.060×0.014×0.013
1.753–32.263
−13≤h≤13
−24≤k≤24
−25≤l≤25
γ (°)
V (Å3)
Z
Dcalc (Mg/m3)
Abs coeff (mm−1
Cryst size (mm3)
)
Synthesis of [W(CO)4(PPh3)(pip)] (1)
θ range for data coll
Index ranges
Cis-[W(CO)4(pip)2] (1.40 g, 3 mmol) and PPh3 (1.58 g,
6 mmol) were placed in a 100 mL Schlenk flask under nitro-
gen. 60 mL CH2Cl2 was added and the solution refluxed for
~10 min. The reaction was cooled to room temperature and
the filtered through diatomaceous earth. The solvent volume
was reduced by half under vacuum and ~50 mL methanol
was added slowly. The flask was placed in the freezer and
crystals were obtained after 3 days (~30% yield). The yellow
rod like crystals were of suitable quality for X-ray diffraction
studies; see Table 1 for the crystallographic details. 31P{1H}
NMR (121 MHz, CDCl3): 22.1 ppm. An alternative synthe-
sis and additional spectroscopic data for 1 may be found in
reference [11].
Reflns collected
Independent reflns
Abs correction
Data/restraints/param
GOF
44,679
8897 R(int) =0.0805
SADABS
8897/0/311
0.976
Final R indices [I>2σ(I)]
R1 =0.0355
wR2 =0.0648
R indices (all data)
CCDC no.
R1 =0.0599
wR2 =0.0721
1403755
X‑ray Crystallography
details may be found in Table 1. Crystallographic data for
the structure reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre (CCDC
1403755). Copies of the data can be obtained free of charge
at http://www.ccdc.cam.ac.uk.
Single crystals of cis-[W(CO)4(PPh3)(pip)] (1) were
obtained by slow diffusion of methanol into a saturated
CH2Cl2 solution of cis-[W(CO)4(PPh3)(pip)]. The data were
collected at 100 ( 1) K on a Bruker APEX CCD diffractom-
eter with Mo Kα radiation (λ=0.71073 Å). A detector-to-
crystal distance of 4.94 cm was used along with 0.5° rotation
about ω between frames and an exposure time of 10 s per
frame. Data collection was optimized utilizing the APEX2
software package. Data integration, correction for Lorentz
and polarization effects, and final cell refinement were per-
formed using SAINTPLUS, SADABS was utilized to correct
for absorption. The structure of 1 was solved using direct
methods followed by successive least squares refinement
on F2 using the SHELXTL software package [12, 13]. All
non-hydrogen atoms were refined anisotropically and hydro-
gen atoms placed in calculated positions. Crystallographic
Results and Discussion
Complex 1, cis-[W(CO)4(PPh3)(pip)], was synthesized in
modest yield by the reaction of cis-[W(CO)4(pip)2] with
PPh3 in refluxing CH2Cl2, Scheme 1. Addition of metha-
nol to the CH2Cl2 solution resulted in the formation of pale
yellow rods after 3 days in the freezer. A yellow rod was
selected and placed on the X-ray diffractometer for data col-
lection. The crystal data and structure refinement informa-
tion are provided in Table 1.
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Journal of Chemical Crystallography
Table 2 Selected bond lengths (Å) and angles (°) for cis-
[W(CO)4(pip)(PPh3)] (1)
CO
W
H
N
OC
OC
Reflux
CH2Cl2
cis–[W(CO)4(pip)2]
+
PPh3
Bond lengths
W1–C1
W1–C2
W1–C3
W1–C4
W1–N1
W1–P1
P1–C22
PPh3
CO
1.945 (4)
1.983 (4)
2.023 (4)
2.041 (4)
2.322 (3)
2.5444 (9)
1.829 (4)
1.834 (3)
1.842 (3)
1.488 (4)
N1–C5
N1–H
1.493 (4)
0.80 (4)
Scheme 1 Synthesis of cis-[W(CO)4(pip)(PPh3)]
O1–C1
O2–C2
O3–C3
O4–C4
C5–C6
C6–C7
C7–C8
C8–C9
1.175 (4)
1.153 (4)
1.150 (4)
1.152 (4)
1.524 (5)
1.514 (5)
1.526 (5)
1.521 (5)
The solid state structure of cis-[W(CO)4(pip)(PPh3)]
is, as expected, similar to related complexes such as: cis-
[Mo(CO)4(pip)(PPh2(p-C6H4F))] [5], cis-[Mo(CO)4(pip)
(PPhMe2)] [4], cis-[Mo(CO)4(pip)(P(OMe)3)] [3], and cis-
[W(CO)4(pip)(P(OPh)3)] [2]. Figure 1 contains a thermal
ellipsoid representation of 1 along with the atomic num-
bering scheme. Selected bond lengths and angles may be
found in Table 2. Packing diagrams for 1 may be found
in Figs. 2 and 3. The closest phenyl phenyl interaction is
>5 Å between adjacent molecules. The geometry about the
metal center is that of a distorted octahedron with angles
of the trans ligands found to be: 177.01° (N1–W1–C1),
174.79° (P1–W1–C2), and 168.59° (C3–W1–C4). The
N1–W1–P1 angle of 86.56° observed for 1 is very close
to that reported for cis-[W(CO)4(pip)PH(t-Bu)(Mes)]
(85.97°) [9], cis-[Mo(CO)4(pip)(P(OMe)3)] (86.3°) [3],
cis-[Mo(CO)4(pip)(PPh2(p-C6H4F))] (86.28°) [5], and
slightly more acute than observed for cis-[W(CO)4(pip)
(P(OPh)3)] (88.23) [2]. Each of these previously reported
piperidine complexes exhibit an intramolecular hydro-
gen bond, often between the N–H of piperidine and the
oxygen of the phosphite or an NH and arene π system.
P1–C16
P1–C10
N1–C9
Bond angles
C1–W1–C2
C1–W1–C3
C2–W1–C3
C1–W1–C4
C2–W1–C4
C3–W1–C4
C1–W1–N1
C2–W1–N1
C3–W1–N1
C4–W1–N1
C1–W1–P1
C2–W1–P1
C3–W1–P1
C4–W1–P1
N1–W1–P1
89.04 (14)
82.72 (14)
88.32 (14)
86.87 (15)
86.85 (14)
168.59 (14)
177.01 (13)
91.29 (13)
94.32 (12)
96.12 (13)
92.86 (10)
174.79 (10)
87.11 (10)
98.09 (10)
86.56 (7)
C9–N1–C5
C9–N1–W1
C5–N1–W1
O1–C1–W1
O2–C2–W1
O3–C3–W1
O4–C4–W1
N1–C5–C6
C22–P1–C16
C22–P1–C10
C16–P1–C10
C22–P1–W1
C16–P1–W1
C10–P1–W1
110.0 (3)
116.6 (2)
113.9 (2)
177.0 (3)
177.7 (3)
172.2 (3)
171.7 (3)
112.4 (3)
101.73 (16)
105.35 (15)
103.83 (15)
112.45 (11)
120.57 (11)
111.43 (11)
cis-[W(CO)4(pip)2], with an N–W–N angle of 85.90°,
was reported to take part in significant hydrogen bond-
ing lowering νCO to as low as 1768 cm−1 [14]. In
cis–[W(CO)4(pip)(PPh3)] (θ for pip = 121° [15]) a weak
interaction between the N–H bond and the π system of
PPh3 is observed with a H1N⋯C15 distance of 2.537 Å and
a H1N⋯C10 distance of 2.653 Å (H1N⋯arene centroid
2.958 Å). A very similar interaction was observed in cis-
[Mo(CO)4(pip)(PPh2(p-C6H4F))] [5]. This weak interac-
tion may help account for the acute N–W–P angle in 1. In a
related complex, [W(CO)4(pip)(κ1-P-PTA=C(C6H4OCH3)
NH2)], the P1–W1–N1 angle is slightly larger than in 1 at
94.87° [10]. This complex also contains an N–H bond
interacting with a π system in a more central position on
the arene relative to 1. The H1N⋯arene centroid distance
is significantly shorter at 2.557 Å [10]. P1–M–P2 angles
for cis-[M(CO)4L2] complexes (where M = W or Mo) are
typically > 90° and vary with cone angle. For example cis-
[Mo(CO)4(PPh3)2] exhibits a P–M–P angle of 104.6° (θ
for PPh3 = 145°) [16], substituting PMe2Ph (θ = 122°) or
PMePh2 (θ = 136°) resulted in P–M–P angles of 94.8° and
92.5° respectively [4]. Even cis-[W(CO)4(PTA)2], where
Fig. 1 Thermal ellipsoid representation (50%) of cis-[W(CO)4(pip)
(PPh3)] containing the atomic numbering scheme. Hydrogen atoms,
with the exception of that on N1, have been omitted for clarity
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Journal of Chemical Crystallography
Conclusion
The structure of cis-[W(CO)4(pip)(PPh3)] (1) adds to a short
list of structurally characterized examples of mixed phos-
phine–piperidine substituted tungsten carbonyl complexes.
This complex exhibits a weak N–H⋯π interaction and a
slightly shortened W–P bond length, but is otherwise similar
to the previously reported compounds.
Acknowledgements Support from the National Science Founda-
tion (CHE-0226402) is acknowledged for funding for the X-ray
diffractometer.
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