Peri-substituted phosphino-phosphonium salts: Synthesis and reactivity

Article abstract of DOI:10.1021/om400259h

The clean reaction of 5-lithio-6-(diisopropylphosphino)acenaphthene with dichlorophosphines RPCl₂ gives the peri-substituted phosphino-phosphonium salts [Acenap(PiPr₂)(PR)]⁺Cl ^- (2, R = Ph; 3, R = Fc; 4, R = NMe₂; 5, R = iPr; Acenap = acenaphthene-5,6-diyl). Their ionic structure is maintained in solution and in the solid state. The reduction of 2 and 3 with LiAlH₄ led to the formation of mixed tertiary/secondary chelating bis(phosphines) Acenap(PiPr ₂)(PRH) (6 and 7), which were subsequently reacted with PtCl ₂(cod) to give the complexes [(6)/(7)PtCl₂] (8 and 9). Reaction of 2 and 3 with a large excess of MeOTf at elevated temperature gave the chiral 1,2-diphosphoniums [Acenap(PiPr₂)(PRMe)] ²⁺([TfO]^-)₂ (10 and 11), which were reduced with LiAlH₄ to the heteroleptic bis(phosphines) Acenap(PiPr ₂)(PRMe) (12 and 13); these were then reacted with [(nor)Mo(CO) ₄] to give the complexes [(12)/(13)Mo(CO)₄] (14 and 15). The heteroleptic bis(phosphines) 6, 7, 12, and 13 display large through-space couplings (formally ⁴J_PP = 163-199 Hz), comparable in magnitude to ¹J_PP couplings observed in phosphino-phosphonium salts 2-5 (303-412 Hz). Single-crystal X-ray structures of 2, 3, 7-9, 14, and 15 are reported.

Full text of DOI:10.1021/om400259h

Article
pubs.acs.org/Organometallics
peri-Substituted Phosphino-Phosphonium Salts: Synthesis and
Reactivity
Matthew J. Ray, Alexandra M. Z. Slawin, Michael Buhl, and Petr Kilian*
̈
School of Chemistry, EaStChem, University of St Andrews, Fife KY16 9ST, U.K.
S
* Supporting Information
ABSTRACT: The clean reaction of 5-lithio-6-(diisopropylphosphino)acenaphthene with dichlorophosphines RPCl2 gives the
peri-substituted phosphino-phosphonium salts [Acenap(PiPr2)(PR)]+Cl− (2, R = Ph; 3, R = Fc; 4, R = NMe2; 5, R = iPr; Acenap
= acenaphthene-5,6-diyl). Their ionic structure is maintained in solution and in the solid state. The reduction of 2 and 3 with
LiAlH4 led to the formation of mixed tertiary/secondary chelating bis(phosphines) Acenap(PiPr2)(PRH) (6 and 7), which were
subsequently reacted with PtCl2(cod) to give the complexes [(6)/(7)PtCl2] (8 and 9). Reaction of 2 and 3 with a large excess of
MeOTf at elevated temperature gave the chiral 1,2-diphosphoniums [Acenap(PiPr2)(PRMe)]2+([TfO]−)2 (10 and 11), which
were reduced with LiAlH4 to the heteroleptic bis(phosphines) Acenap(PiPr2)(PRMe) (12 and 13); these were then reacted with
[(nor)Mo(CO)4] to give the complexes [(12)/(13)Mo(CO)4] (14 and 15). The heteroleptic bis(phosphines) 6, 7, 12, and 13
4
1
display large through-space couplings (formally JPP = 163−199 Hz), comparable in magnitude to JPP couplings observed in
phosphino-phosphonium salts 2−5 (303−412 Hz). Single-crystal X-ray structures of 2, 3, 7−9, 14, and 15 are reported.
INTRODUCTION
■
Stabilization of low-valent main-group species by the
coordination of a Lewis base has allowed the isolation of
many exotic and otherwise unstable structural motifs.1 While
phosphino-phosphonium cations (R3P+−PR2) can be viewed as
+
a class of quasi-phosphonium salts (PR4 ) having a −PR2 group
as one of its four substituents, they can also be viewed as
donor−acceptor complexes, in which a reactive low-coordinate
(phosphenium) species is stabilized by a Lewis base (a tertiary
phosphine). The latter description is represented by the Lewis
+
structure R3P→PR2 . Both structural descriptions are justifiable,
as examples of reactivities expected from each of these bonding
interpretations are known.
Synthetic methods for phosphino-phosphonium salts are
closely interlinked with the chemistry of “free” (low-
2
+
coordinate) phosphenium cations (PR2 ). Free phospheniums
are generally formed by halide abstraction from halophos-
phines. Addition of a phosphine to such free phospheniums
gives phosphino-phosphonium salts, such as A and B (Figure
1).3,4 Early examples involved amido substituents on the
phosphorus, which stabilize the electron-deficient phosphe-
niums via π-donation from the nitrogen atoms. The “all carbon”
free phosphenium Fc2P+ (Fc = ferrocenyl) was reported in
1981,5 and the related phosphino-phosphonium cation
[nBu3PPFc2]+ (D) was reported soon after.6 The first crystal
structures of phosphino-phosphonium salts C (with two
different counteranions) were reported by Schomburg in
Figure 1. Phosphino-phosphonium salts.
1984.7 P−P distances in these examples as well as in others
are around 2.20 Å, within a typical range for a single P−P bond.
A large series of “all carbon” phosphino-phosphonium salts
(D) was synthesized and well characterized by Burford, mostly
in the past decade. These and others were reviewed extensively
Received: March 27, 2013
© XXXX American Chemical Society
A
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up to 2008,8 and several additional papers from Burford have
appeared since.9,10 Notably, a modified synthetic method was
used to make phosphino-phosphonium salts D. A three-
component reaction takes place among a chlorophosphine, a
halide abstractor, and a donor phosphine. The free
phosphenium is not isolated (or even detected); instead, it is
“trapped” by a phosphine donor to form the phosphino-
phosphonium cation.
Preparation of phosphino-phosphonium chlorides by the
reaction of trialkylphosphines and chlorophosphines without
the presence of a halide abstractor (a variation on the historic
synthesis by Seidel and Sisler11) was revisited by Burford
recently.12
phosphonium salt with organolithiums or Grignard reagents
resulted in P−P bond cleavage and formation of two tertiary
phosphine functionalities.17a
We have an ongoing interest in the chemistry of peri-
substituted phosphorus compounds. Forced interactions across
the peri positions often lead to novel reactivity not observed in
comparable intermolecular reactions.25 To date, several peri-
substituted phosphino-phosphonium salts were reported by
Schmutzler21 and us.23,26
We have recently reported that lithiation of 1 and subsequent
reaction with PCl3 led to the formation of the first room-
temperature-stable phosphine-phosphine complex (E; see
Scheme 2).27
The most studied reactivity of phosphino-phosphonium salts
to date is the formation of 1,2-diphosphonium salts (R3P+−
P+R3) by reacting phosphino-phosphonium salts with strong
alkylating reagents, such as MeOTf or, less commonly,
Me3OBF4 or GaCl3/tBuCl. Many of the phosphino-phospho-
nium salts discussed above were synthesized with dication
preparation in mind. These reactions have been extensively
studied by Burford,13,14 building on pioneering work by
Schmutzler15 and Alder.16,17
Scheme 2. Synthesis of a Room-Temperature-Stable
Phosphine-Phosphine Complex
A variety of ligand exchange reactions of phosphino-
phosphonium cations have been reported. Both (1) phosphine
+
(PR3) exchange at the phosphenium (PR2 ) Lewis acceptor site
Since the reaction shown in Scheme 2 gave such an unusually
thermally stable product, we were intrigued as to whether a
similar stabilizing effect of the peri interaction would be
observed in the related reaction of the same lithiated precursor
with dichlorophosphines RPCl2, possibly via formation of stable
products analogous to E. However, due to the lower
electrophilicity of the acceptor center in the latter, the products
adopt ionic (phosphino-phosphonium salt) rather than neutral
molecular (phosphine-phosphine) structures (see Figure 5).
The results of our synthetic investigations of the phosphino-
phosphonium salts are discussed below.
and (2) phosphine- or phosphonium-substituent exchanges are
plausible. An example of the first type of exchange is given in eq
1; in this reaction the chlorophosphine moiety is being replaced
ClR2P+−PR2 + PR′3 → R′3P+−PR2 + R2PCl
(1)
with a more strongly donating tertiary phosphine.8,18 Such a
phosphine exchange is an example of donor−acceptor complex
like reactivity of phosphino-phosphonium cations. The
mechanism of exchange was studied by Russell19 and Baker20
in some detail.
The second type of exchange reactions of phosphino-
phosphonium cations are those where a substituent on either
phosphorus center is replaced, but not the whole functionality.
These are commonplace for amido-substituted species; the
−NR2 groups are easily replaced with chloride, generally
without disturbance of the P−P bond. An example from the
group of Schmutzler is shown in Scheme 1.21 Other examples
were reported by Bickelhaupt22 and us.23 A variety of halide
sources was used in these reactions such as HCl, BCl3·Et2O,
and P2I4.
RESULTS AND DISCUSSION
■
Phosphino-Phosphonium Chlorides 2−5. A series of
phosphino-phosphonium chlorides 2−5 was synthesized using
the bromide 1 as the principal starting material. Thus, 5-lithio-
6-(diisopropylphosphino)acenaphthene was obtained from 1
by a low-temperature lithium−halogen exchange reaction and
was then reacted with selected dichlorophosphines RPCl2 (R =
Ph, Fc, NMe2, iPr) (see Scheme 3). In the case of 2−4, 1 equiv
of the dichlorophosphine was sufficient to achieve the desired
reactivity. In case of 5, though, it was necessary to reverse the
order of addition and use a 3-fold excess of iPrPCl2, in order to
avoid formation of the previously reported geminally bis(peri-
substituted) tridentate phosphine product.28 For 2, 3, and 5
efficient removal of the salt byproducts was achieved via
washing with degassed water, indicating that they are stable
toward hydrolysis. As 4 decomposes on contact with water, its
salt byproducts were removed by filtration using filtration aid
(Celite). Further details of workup procedures differed slightly
for each of 2−5.
Scheme 1. Example of a Substitution Reaction of an Amido
Phosphino-Phosphonium Salt
Following the general procedure outlined above using
PhPCl2, the phosphino-phosphonium chloride 2 was obtained
as a colorless oil after removal of volatiles in vacuo. Washing
with diethyl ether and toluene gave 2 as a white powder in 97%
yield. Purer material was obtained after precipitation from 1,2-
dichloroethane/toluene. The 31P{1H} NMR spectrum of 2
A small number of reactions of phosphino-phosphonium
salts in which the P−P bond is broken have also been reported.
Alkaline hydrolysis of a bicyclic phosphino-phosphonium salt
with a transannular P−P bond resulted in cleavage of this bond
and formation of phosphine oxide and secondary phosphine
functionalities.24 Reaction of another bicyclic phosphino-
1
consists of two doublets at δP −34.5 and 60.0 ppm, JPP = 303
Hz, corresponding to the phosphino and phosphonium
B
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Scheme 3. Synthesis of Compounds 2−15
1
moieties, respectively. 2 was further characterized by H and
13C{1H} NMR, IR, Raman, and ES MS, including exact mass
determination (HRMS).
Crystals of 2 suitable for X-ray crystallography were grown
from MeCN. The X-ray crystal structure of 2 is shown in Figure
2, and selected bond lengths and angles are given in Table 1.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 2,
3·0.5 MeCN, and 7
Compound 2
C1−P1
1.833(3)
90.17(8)
C9−P9
C9−P9−P1
Compound 3·0.5 MeCN
1.793(3)
98.21(8)
C1−P1−P9
C1−P1
1.842(5)
C13−P1
1.803(5)
C9−P9
C1−P1−P9
C13−P1−C1
1.791(5)
89.23(14)
100.5(2)
C9−P9−P1
98.96(14)
C13−P1−P9
102.03(15)
Compound 7
C1−P1
H1−P1
C1−P1−H1
C13−P1−C1
1.856(5)
C9−P9
C13−P1
C13−P1−H1
1.847(5)
1.822(4)
94.2(11)
1.325(19)
104.7(15)
101.58(19)
Figure 2. Crystal structure of 2 with ellipsoids drawn at the 50%
probability level. The chloride counterion and hydrogen atoms are
omitted for clarity.
Figure 3. Definition of a splay angle.
The crystal structure confirms the ionic nature of 2 with a
phosphino-phosphonium cation and a chloride counteranion.
The P−P bond length in 2 is 2.2347(9) Å, typical of a single
The phosphino-phosphonium chloride 3 was obtained from
FcPCl2 via the coupling reaction shown in Scheme 3. 3 was
isolated as an orange solid in 98% yield. The 31P{1H} NMR
bond (normal range 2.20
0.05 Å). The geometry around
spectrum of 3 is very similar to that of 2, exhibiting two
1
both phosphorus centers shows a few significant deviations
from the ideal tetrahedral angle, the most acute angle being
C1−P1−P9 (90.17(8)°), where the geometry is forced by the
rigid acenaphthene backbone. 2 has a splay angle (see Figure 3
for a definition) of −8.85(18)°, the negative value of which is
consistent with an attractive interaction (i.e., a bond) across the
peri gap. Overall, the molecular geometry of 2 is rather relaxed;
the acenaphthene ring is planar, and both phosphorus atoms lie
rather close to the mean acenaphthene ring plane (the
displacements are 0.142 and 0.274 Å for P1 and P9,
respectively).
doublets at δP −36.2 ppm (FcP) and 54.6 ppm (iPr2P), JPP
=
311 Hz. 3 was further characterized by 1H and 13C{1H} NMR,
IR, Raman, and ES MS, including HRMS, and its purity was
verified by microanalyses.
Crystals of 3 suitable for X-ray crystallography were grown
from MeCN. The X-ray crystal structure of 3 is shown in Figure
4, and selected bond distance and angles are given in Table 1. 3
cocrystallizes with half a molecule of MeCN, but the structure
is otherwise largely analogous to that of 2, including the angular
distortions around the phosphorus centers (see Table 1). The
P−P bond length in 3 is 2.2483(17) Å.
C
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2−5 encourages dissociation (see Figure 5). In addition to
electronic effects, steric reasons also favor dissociation of
Figure 5. Molecular (left) vs ionic (right) structure of 2−5. The ionic
structure is observed in both the solid state and solution for 2−5.
Figure 4. Crystal structure of 3 with ellipsoids drawn at the 50%
probability level. The chloride counterion, the cocrystallized molecule
of MeCN (hemisolvate), and hydrogen atoms are omitted for clarity.
chloride in 2−5, as the organic substituent or amino group is
more difficult to accommodate comfortably in the pseudo-
trigonal-bipyramidal molecular geometry (in 2′−5′) than in the
pseudo-tetrahedral geometry (seen in 2−5).
Reaction of 1 with nBuLi followed by addition of
(NMe2)PCl2 was performed under the same conditions as for
the above preparations of 2 and 3. The 31P{1H} NMR
spectrum of the mixture after the reaction revealed that the
desired phosphino-phosphonium chloride 4 was formed (as an
AB spin system, δP 36.2 ((NMe2)P) and 66.2 ppm (iPr2P), 1JPP
= 412 Hz, ca. 77% of integral intensity). However, other
phosphorus-containing products were also formed in significant
quantities, which is in contrast with the near-quantitative
conversions achieved for 2 and 3. Despite our numerous
attempts, we have been unable to purify 4 by recrystallization or
other methods. Hence, 4 was characterized by 31P NMR and
Mixed Tertiary/Secondary Bis(phosphines) 6 and 7.
Reduction of 2 with LiAlH4 in thf, followed by quenching and
washing with water, gives the heteroleptic bis(phosphine) 6 as a
pale yellow oil in 85% yield. The 31P{1H} NMR spectrum of 6
displays two doublets at δP −41.0 (Ph(H)P) and −12.3 ppm
4
(iPr2P), JPP = 169 Hz. The 31P NMR spectrum (1H coupled)
exhibits an additional large coupling of the secondary
phosphine signal (1JPH = 202 Hz), while the complexity of
the iPr2P phosphorus signal does not allow direct reading of the
5
across peri-gap JPH coupling. However, the latter coupling
1
constant was obtained from the H NMR spectrum, where the
hydrogen directly bonded to phosphorus atom gives a doublet
1
1
5
mass spectrometry only. Notably, the JPP coupling constant
of doublets with JHP = 202 Hz and JHP = 57.6 Hz, the large
magnitude of both indicating a significant through-space
component. 6 is extremely soluble in organic solvents, and
evaporation of solvents leads to an oil, which has not proved to
be amenable to crystallization. We have used this oil for further
characterization by 1H and 13C{1H} NMR and ES MS,
including HRMS; it was of sufficient purity for further synthetic
use.
(412 Hz) in 4 is of considerably higher magnitude than related
couplings observed in 2 (303 Hz) or 3 (311 Hz), possibly due
to the stronger electron-donating nature of the dimethylamino
group in comparison with phenyl or ferrocenyl. Because of the
difficulties with purification of 4, no further synthetic use was
attempted.
As alluded to above, the synthesis of the phosphino-
phosphonium chloride 5 required a modified synthetic
procedure; in particular, reversing the order of addition of
reactants resulted in improved selectivity of the reaction toward
5. A suspension of 5-lithio-6-(diisopropylphosphino)-
acenaphthene was thus added to a 3-fold excess of iPrPCl2 at
−78 °C. A workup procedure similar to that used for 2 gave 5
as a white solid in 94% yield. The 31P{1H} NMR spectrum of 5
consisted of doublets at δP −22.9 (iPrP) and 60.6 (iPr2P) ppm,
1JPP = 306 Hz. We were unable to obtain crystals of 5 suitable
for X-ray crystallography, but the compound was fully
Reduction of 3 with LiAlH4 using the same conditions and
workup procedures as above led to clean formation of 7 as an
orange solid, which was isolated in 89% yield. The 31P{1H}
NMR spectrum of 7 exhibits two doublets at δP −51.9
(Fc(H)P) and −9.3 ppm (iPr2P), 4JPP = 199 Hz. The 31P NMR
(1H coupled) spectrum of 7 revealed a 1JPH coupling of 237 Hz.
1
1
The magnitude of the JPH coupling was confirmed by the H
NMR spectrum, the P−H hydrogen atom giving a doublet of
1
5
doublets with JHP = 237 and JHP = 33.2 Hz.
4
The across peri-gap JPP coupling in 6 and 7 is of magnitude
1
characterized by H and 13C{1H} NMR, Raman, and MS ES,
similar to that observed in “homoleptic” 1,8-bis-
(diphenylphosphino)naphthalene (dppn) by MAS solid-state
NMR (199 Hz).29 Acenap(PiPr2)(P(OPh)2) (Acenap =
acenaphthene-5,6-diyl) is the only literature example of a
“heteroleptic” species with two different phosphorus(III)
moieties at the peri positions, which allows direct observation
and its purity was verified by microanalyses.
It is interesting to note that chloride dissociation is not
observed in the solid-state structure of the related phospho-
nium-phosphoranide E;27 hence, E has a molecular character.
This is in contrast with the ionic structures of 2−5, which exist
as phosphino-phosphonium cations with chloride counter-
anions in solution (as judged from their 31P NMR chemical
shifts) and in the solid state (from single-crystal X-ray
diffraction). Thus, the less electron-withdrawing nature of the
aryl, dimethylamino, and isopropyl substituents in compounds
4
of its P···P coupling. JPP coupling with a magnitude of 199.5
Hz was observed in this compound, again in good agreement
with the relevant values in 6 and 7.27
Crystals of 7 suitable for X-ray crystallography were obtained
from a concentrated solution in hexane. The X-ray crystal
D
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structure of 7 is shown in Figure 6, and selected bond distances
and angles are given in Table 1. The P1···P9 distance in 7 is
further characterized by 1H and 13C{1H} NMR, IR, Raman, and
ES MS, and its purity was verified by microanalyses.
Crystals of 8 suitable for X-ray crystallography were grown
from CH2Cl2 and diethyl ether. The crystal structure of 8 is
shown in Figure 7, and selected bond distances and angles are
Figure 6. Crystal structure of 7 with ellipsoids drawn at the 50%
probability level. Carbon-bound hydrogen atoms are omitted for
clarity.
Figure 7. Crystal structure of 8 with ellipsoids drawn at the 50%
probability level. Carbon-bound hydrogen atoms are omitted for
clarity.
3.05 Å, in keeping with values previously reported for 1,8-
bis(phosphino)naphthalenes, which range from 2.9092(7) to
3.070(1) Å.29−33 Hence, it would appear that the small steric
bulk of the secondary phosphine center does not lead to a
shorter peri distance. The repulsive P···P interaction results in a
positive splay angle of +12.1(4)° and an increase in out-of-
plane displacement for P1 (0.373 Å) and P9 (0.156 Å) in
comparison with relevant values for the phosphino-phospho-
nium chloride 3.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 8,
9·MeCN, 14, and 15
Complex 8
P1−Pt1
P1−Pt1−P9
2.2006(13)
95.19(6)
P9−Pt1
Cl1−Pt1−Cl2
2.2455(15)
88.19(5)
Bis(phosphine) 7 was further characterized by 1H and
13C{1H} NMR, IR, Raman, and ES MS, including HRMS.
Platinum(II) Complexes 8 and 9. Bis(phosphines) 6 and
7 represent the first examples of peri-substituted mixed tertiary/
secondary phosphines. Due to the ease of their synthesis, they
have the potential to become a useful new class of P-chiral
heteroleptic chelating ligands. As a preliminary study into their
coordination properties, racemic platinum(II) chloride com-
plexes 8 and 9 have been prepared and fully characterized.
Treatment of 6 with PtCl2(cod) (cod = 1,5-cyclooctadiene)
in CH2Cl2 at room temperature, followed by evaporation of
volatiles, gives [(6)PtCl2] (8) as a white solid in quantitative
yield. The 31P{1H} NMR spectrum of 8 exhibits two doublets
Complex 9·MeCN
P1−Pt1
P1−Pt1−P9
2.1931(15)
93.25(6)
P9−Pt1
Cl1−Pt1−Cl2
2.2426(15)
89.28(5)
Complex 14
P1−Mo1
P1−Mo1−P9
2.4720(12)
P9−Mo1
2.5300(13)
2.554(6)
86.96(4)
Complex 15
2.506(5) P9−Mo1
P1−Mo1
P1−Mo1−P9
84.37(17)
given in Table 2. The geometry about the platinum center is
slightly distorted square planar. Interestingly, the P1···P9
distance in 8 (3.28 Å) is intermediate between those in acyclic
cis-PtCl2(PPh3)2 (3.44 Å)34 and cis-PtCl2(Ph2P(CH2)3PPh2)
(3.20 Å),35 the latter containing a flexible C3 backbone. This
indicates that the steric properties of the rigid ligand 6 are
rather favorable for η2-square-planar coordination. Interestingly,
while the P1−Pt1 bond distance (2.2006(13) Å) is slightly
shorter than the P9−Pt1 distance (2.2455(15) Å) in 8,36 this is
not mirrored in the expected 1JPPt trend (a shorter bond results
2
at δP −20.9 (Ph(H)P) and 14.8 ppm (iPr2P), JPP = 25.4 Hz.
Both doublets are accompanied by a set of 195Pt satellites (1JPPt
= 3212 (Ph(H)P) and 3397 Hz (iPr2P)). In the 31P NMR (1H
coupled) spectrum of 8 an additional large splitting from the
hydrogen directly bonded to phosphorus atom is observed,
1
with JPH = 451 Hz. The 195Pt{1H} NMR spectrum of 8
revealed the anticipated doublet of doublets centered at δPt
1
−4504 ppm, with the JPtP coupling constants corresponding
1
1
well with those found in the 31P{1H} NMR spectrum. The H
in a greater J magnitude). Instead, JP1−Pt coupling (3212 Hz)
NMR spectrum of 8 shows a doublet of doublets for the
corresponding to the shorter bond has a smaller magnitude
than the JP9−Pt (3397 Hz) coupling, corresponding to the
1
1
hydrogen bonded directly to the phosphorus atom with JHP
=
3
451 Hz and JHP = 21.0 Hz. Notably, the through-space H−
longer P−Pt bond.
5
P···P coupling (formally JHP) in the free ligand 6 is of larger
To shed light on the unexpected Pt−P distance/J-coupling
relation, we performed density functional theory (DFT)
computations on complex 8. The PBE0/ECP1 optimized Pt−
magnitude (57.6 Hz) than the related H−P−Pt−P coupling
3
(formally JHP) in the complex 8 (21.0 Hz). Complex 8 was
E
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P1 and Pt−P2 distances, 2.216 and 2.268 Å, respectively, are
somewhat overestimated in comparison to the X-ray diffraction
values (see above),37 but the overall trend is reproduced quite
1
well. Calculated JPPt values are collected in Table 3.
1
Table 3. ZORA-SO/BP86/TZ2P Computed JPPt Values
(Hz) for Complex 8
a
entry
complex
Pt1−P1(H)Ph
Pt1−P9(iPr)2
1
2
3
8//8
2344
2060
2211
2426
1961
2211
8H//8
8H//8H
a
8H is the parent complex with the acenaphthene-4,5-diphosphine
(C12H8-4,5-(PH2)2) ligand. The notation A//B means that complex A
uses the structural parameters optimized for complex B.
For the fully optimized structure of 8 (entry 1) the
quantitative agreement with experiment is not impressive (the
experimental numbers are underestimated by ca. 900 Hz);
however, this is in line with previous findings at related levels.38
Nonetheless, the qualitative trend of a larger coupling constant
for the longer bond is well captured computationally. Entry 2 is
for the parent molecule 8H (acenaphthene-5,6-diphosphine,
C12H8-5,6-(PH2)2), but using the structural parameters of 8
(i.e., with the Ph and iPr groups replaced by H atoms without
further optimization). The difference with respect to entry 1 is
thus the direct electronic effect of the substituents. Apparently
two iPr groups enhance the coupling more strongly (by nearly
500 Hz) than one Ph (nearly 300 Hz), so that entry 2 has the
expected sequence (smaller coupling for the longer bond).
Entry 3 corresponds to the fully relaxed parent 8H, which
optimizes to a fully planar structure (save for the phosphine H
atoms) with C2v symmetry (Pt−P distance 2.215 Å). The
difference from entry 2 is thus the effect of the structural
distortion brought about by the bulky substituents. This is
more pronounced for P9 (which would carry the two iPr
groups), for which the coupling decreases noticeably,
concomitant with the increase in the Pt−P distance. This
effect, however, is outweighed by the electronic effect of the iPr
groups that serves to increase the coupling, to the extent that
Figure 8. Crystal structure of 9 with ellipsoids drawn at the 50%
probability level. The cocrystallized molecule of MeCN and carbon-
bound hydrogen atoms are omitted for clarity.
1
1
and JP1Pt1 = 3159 Hz vs P9−Pt1 = 2.2426(15) Å and JP9Pt1
=
3456 Hz).
1,2-Diphosphonium Salts 10 and 11. The alkylation
reactions of the phosphine centers in 2 and 3 were investigated
with a view to the formation of 1,2-diphosphoniums. Neither 2
nor 3 reacts with an excess of MeOTf in 1,2-dichloroethane at
room temperature or on heating under reflux (at 84 °C).
However, the reaction of 2 or 3 with a large excess of neat
MeOTf at 90 °C did yield the desired 1,2-diphosphoniums 10
and 11 (Scheme 3). The extremely forcing conditions resulted
in the formation of significant amounts of unidentified side
products; integration of the 31P NMR spectra of the mixtures
after reaction revealed conversion to 10 was ca. 70% and that to
11 was ca. 60%.
10 was obtained as a pale yellow oil after evaporation of
volatiles in vacuo. The 31P{1H} NMR spectrum of 10 exhibited
an AB spin system with δP 31.0 (Ph(Me)P) and 52.8 ppm
(iPr2P), with a low magnitude of 1JPP coupling (27.6 Hz), which
is consistent with the suggested 1,2-diphosphonium structure
(see below). Despite many attempts, we have been unable to
further purify or crystallize 10. However, ES MS data provide
evidence for its formation; the adduct of the dication with OH
(the partial hydrolysis product) was observed in the ES+
spectrum, and such an adduct has been identified as the
characteristic peak in other 1,2-diphosphoniums previously.26
In addition, we have identified products of further trans-
formations of 10 (see below), which unambiguously confirm
the 1,2-diphosphonium structure of 10.
1
the longer bond in 8 has the higher JPPt value.
The platinum complex [(7)PtCl2] (9) was obtained as an
orange solid in quantitative yield from the reaction of 7 and
PtCl2(cod) in CH2Cl2. The 31P{1H} NMR spectrum of 9 is
similar to that of 8; it consists of an AB spin system (two
doublets) at δP −17.4 (Fc(H)P) and 14.6 ppm (iPr2P) (2JPP
=
1
25.6 Hz) with 195Pt satellites, JPPt = 3159 (Fc(H)P) and 3456
Hz (iPr2P). The 31P NMR spectrum revealed additional large
splitting of the secondary phosphine resonance from the
The 31P{1H} NMR spectrum of 11 consists of two doublets
1
phosphine hydrogen atom with JPH = 468 Hz.
1
1
at δP 33.2 (Fc(Me)P) and 47.9 ppm (iPr2P), JPP = 45.4 Hz.
The H NMR spectrum of 9 is very broad, which made
The markedly higher P−P coupling could be down to the more
electron donating nature of the ferrocenyl vs the phenyl group;
a similar difference was observed in the 4JPP coupling constants
in 6 and 7 (see Table 4). The identity of 11 was further
confirmed via identification of the products of its further
transformations (see below).
detailed assignment of peaks difficult. 9 is poorly soluble in
common organic solvents, which prevented its characterization
by 13C{1H} and 195Pt{1H} NMR spectroscopy; however, we
characterized it by IR, Raman, and ES MS, including HRMS,
and its purity was verified by microanalyses.
Crystals of 9 (MeCN solvate) suitable for X-ray crystallog-
raphy were obtained from a solution in MeCN. The crystal
structure is shown in Figure 8, and selected bond distances and
angles are given in Table 2. The structure of 9 is in many ways
analogous to that of 8. As observed above for 8, the shorter of
the two P−Pt distances in 9 corresponds with a smaller
magnitude of observed 1JPPt coupling (P1−Pt1 = 2.1931(15) Å
31P{1H} NMR confirmed the formation of 1,2-diphospho-
niums 10 and 11 rather unambiguously due to the uniquely low
1JPP coupling constants of 1,2-diphosphoniums. The vast
majority of 1,2-diphosphoniums reported in the literature
possess magnetically equivalent phosphorus atoms, and hence,
1JPP coupling cannot be read from their 31P NMR spectra
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1H and 13C{1H} NMR, Raman, IR, and CI MS, and the purity
was verified by microanalyses.
directly. However, a limited number of “heteroleptic” 1,2-
diphosphoniums are known. Burford prepared a series of such
1,2-diphosphoniums, including Et3P+−P+Me3, nPr3P+−P+Me3,
Reduction of the (impure) 1,2-diphosphonium 11 with
LiAlH4 gave complete conversion to the respective bis-
(phosphine) 13, which was obtained as an orange oil not
amenable to crystallization (ca. 60% purity as judged by 31P
NMR). The 31P{1H} NMR spectrum of 13 is consistent with
two strongly through space coupled phosphine environments;
two doublets at δP −47.5 (Fc(Me)P) and −5.2 ppm (iPr2P),
1
iPr3P+−P+Me3, and Me3P+−P+tBu2Me, in which JPP coupling
constants range from −48.1 to −94.2 Hz.13 A seminal paper
from Schmutzler reported a 1,2-diphosphonium with a
1
remarkably high magnitude of JPP coupling of 219 Hz;
however, this example is electronically and structurally very
dissimilar to our species 10 and 11.15 Hence, 11 has a
4
1
with JPP = 163 Hz, were observed. Like 12, 13 was used for
magnitude of JPP coupling constant at the low end of the
1
further synthesis without purification.
reported range, while 10 exhibits the lowest magnitude of JPP
Reacting (impure) 13 with [(nor)Mo(CO)4] gave [(13)-
Mo(CO)4] (15) as an orange oil after evaporation of volatiles.
Recrystallization from MeCN gave analytically pure 15 as small
brown crystals in 23% yield. The 31P{1H} NMR spectrum of 15
displayed two doublets at δP 4.5 (Fc(Me)P) and 41.6 ppm
coupling reported among 1,2-diphosphoniums so far.
Heteroleptic Bis(phosphines) 12 and 13 and Their
Molybdenum(0) Complexes 14 and 15. In order to explore
the general synthetic utility of heteroleptic 1,2-diphosphoniums
10 and 11, and also to obtain further evidence for their
formation, we subjected them to reduction with LiAlH4 and
subsequent coordination to [(nor)Mo(CO)4] (nor = norbor-
nadiene).
2
(iPr2P), JPP = 30.2 Hz.
Despite our repeated efforts using a variety of solvents, we
have only been able to grow relatively small crystals of 15.
Hence, our structural data are rather poor; however they are
adequate to demonstrate connectivity and support assignment
of the structure. The crystals used for X-ray work were obtained
from MeCN; the crystal structure of 15 is shown in Figure 10,
and selected bond distances and angles are given in Table 2.
The structure of 15 in the crystal is largely similar to that of 14.
Reduction of 10 gave bis(phosphine) 12 as a pale yellow oil.
The 31P{1H} NMR of 12 exhibits two doublets at δP −35.4
4
(Ph(Me)P) and −8.5 ppm (iPr2P), JPP = 169 Hz. The
integration indicated ca. 70% purity of the crude product,
confirming that the transformation from the 1,2-dication 10
was essentially quantitative. Since we were unable to purify the
oily product 12, it was used without further detailed
characterization for the next reaction. The reaction of 12
with [(nor)Mo(CO)4] in CH2Cl2 gave a brown suspension
which, after filtration and removal of the solvent in vacuo, gave
crude [(12)Mo(CO)4] (14) as a brown solid. Analytically pure
14 was obtained by recrystallization from MeCN in 23% yield.
The 31P{1H} NMR spectrum of 14 consists of two doublets at
δP 8.6 (Ph(Me)P) and 42.9 ppm (iPr2P), 2JPP = 35.1 Hz. Some
of the crystals obtained from MeCN were suitable for X-ray
crystallography work. The X-ray crystal structure of 14 is shown
in Figure 9, and selected bond distances and angles are given in
Table 2. As expected, the bis(phosphine) ligand is coordinated
to the octahedral Mo center in a cis fashion. In addition to X-
ray diffraction and 31P{1H} NMR, 14 was fully characterized by
Figure 10. Crystal structure of 15 with ellipsoids drawn at the 50%
probability level. Hydrogen atoms are omitted for clarity.
In addition to X-ray diffraction and 31P{1H} NMR, 15 was
fully characterized by 1H and 13C{1H} NMR and IR
spectroscopy and the purity was verified by microanalyses.
The full characterization of both 14 and 15 provides
unequivocal verification for the formation of 1,2-diphospho-
niums 10 and 11, as shown in Scheme 3.
Due to the heteroleptic substitution patterns of the peri-
substituted species described in this paper, we have been able to
observe P−P coupling constants across the peri gap in variety of
bonding and nonbonding geometries. These are collated in
Table 4. The most striking trend is the difference in magnitude
of 2JPP (in 8, 9, 14, and 15) and 4JPP coupling constants (in 6, 7,
4
12, and 13). The fact that JPP couplings are of much larger
magnitude in spite of a formally longer range illustrates the
significance of through-space coupling, which operates when
Figure 9. Crystal structure of 14 with ellipsoids drawn at the 50%
probability level. Hydrogen atoms are omitted for clarity.
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Bromo-6-(diisopropylphosphino)acenaphthene,27 (Me2N)PCl2,39 and
PtCl2(cod)40 were prepared according to literature procedures. Where
possible, new compounds were fully characterized by 31P, 31P{1H}, 1H,
Table 4. Selected NMR Parameters and P···P Distances for
Compounds 2−15
a
1
and 13C{1H} NMR, including measurement of H{31P}, H−H DQF
compd
JPP type
JPP value (Hz)
P1···P9 distance
2
1J
1J
1J
1J
4J
4J
2J
2J
1J
1J
4J
4J
2J
2J
303
311
412
306
169
199
25.4
25.6
27.6
45.3
169
163
35.1
30.2
2.2347(9)
COSY, H−P HMQC, H−C HSQC, and H−C HMBC experiments.
Measurements were performed at 25 °C unless otherwise indicated;
85% H3PO4 was used as an external standard in 31P, aqueous Na2PtCl6
was used as an external standard in 195Pt, and TMS was used as an
3
2.2483(17)
4
1
internal standard in H and 13C NMR. The NMR numbering scheme
5
6
for compounds 2−15 is shown in Scheme 4. All filtrations were
performed using a sinter of porosity 3.
7
3.05
3.28
3.22
8
Scheme 4. NMR Numbering Scheme for 2−15
9
10
11
12
13
14
15
3.44
3.40
a
From X-ray diffraction.
CCDC 931190−931196 contain supplementary crystallographic
data for this paper. These data can be obtained free of charge via www.
ccdc.cam.ac.uk/data_request/cif, by emailing data_request@ccdc.cam.
ac.uk, or by contacting The Cambridge Crystallographic Data Centre,
12, Union Road, Cambridge CB2 1EZ, U.K. (fax: +44 1223 336033).
[Acenap(PiPr2)(PPh)]+Cl−, Phosphino-Phosphonium Chlor-
ide 2. nBuLi (1.14 mL of 2.5 M solution in hexanes, 2.86 mmol)
was added dropwise to 1 (1.0 g, 2.86 mmol) in diethyl ether (40 mL)
at −78 °C. The mixture was stirred at −78 °C for 2 h. PhPCl2 (0.41
mL, 2.86 mmol) in diethyl ether (9 mL) was added dropwise at −78
°C. The resulting white suspension was stirred at −78 °C for 2 h
before it was warmed to room temperature slowly and stirred for 16 h.
Solvent was removed in vacuo to give a white solid, which was
dissolved in CH2Cl2 (20 mL) and washed with degassed water (2 mL),
and the organic layer was separated. Solvent was removed in vacuo to
give a colorless oil. Washing with diethyl ether (15 mL) then toluene
(5 mL) gave 2 as a white powder, which was dried in vacuo (1.15 g,
97% yield). Purer material was obtained by slow addition of toluene to
a concentrated solution of 2 in 1,2-dichloroethane to give a white
precipitate, which was collected by filtration and dried in vacuo.
Colorless cube-shaped crystals suitable for X-ray crystallography were
grown from MeCN at 2 °C. 1H NMR (300.1 MHz, CD3CN): δ 0.83−
1.38 (m, 12H, 4 × iPr CH3), 2.91−3.06 (m, 1H, iPr CH), 3.26−3.41
(m, 1H, iPr CH), 3.62 (s, 4H, 2 × CH2), 7.32−7.46 (br m, 4H, o/m-
Ph CH), 7.49−7.57 (m, 1H, p-Ph CH), 7.67−7.74 (m, 1H, H7),
7.74−7.80 (m, 1H, H3), 8.07 (t, 1H, J = 7.4 Hz, H8), 8.31 (t, 1H, J =
7.3 Hz, H2). 13C{1H} NMR (67.9 MHz, CD3CN): δ 16.7−17.4 (m, 4
× iPr CH3), 25.1−28.8 (m, 2 × iPr CH), 31.6 (s, CH2), 32.3 (s, CH2),
lone pairs are available on the peri atoms. A particularly
illustrative example of this is seen in the ligand 7 and its Pt
complex 9, which show a drop of coupling constant from (4JPP)
199 Hz to (2JPP) of 25.6 Hz on coordination, while the P···P
distance increases by a mere 5% (from 3.05 to 3.22 Å).
CONCLUSION
■
Phosphino-phosphonium chlorides 2−5, which adopt ionic
structures both in solution and in the solid state, are
synthesized in high yields by P−C coupling of dichlorophos-
phines with 5-lithio-6-(diisopropylphosphino)acenaphthene. It
is likely that the synthetic method used for 2−5 can be
extended toward other derivatives, potentially affording a wide
range of “heteroleptic” phosphino-phosphonium salts. We have
demonstrated the use of phosphino-phosphonium salts 2 and 3
as convenient synthons to make mixed tertiary/secondary
bis(phosphines) 6 and 7 and heteroleptic 1,2-diphosphoniums
10 and 11, although the latter were formed with only 60−70%
conversion. 10 and 11 were reduced to their respective
heteroleptic bis(phosphines) 12 and 13, which were isolated
and fully characterized as their molybdenum(0) complexes 14
and 15. The described transformations demonstrate the
synthetic utility of the phosphino-phosphonium salts toward
a library of heteroleptic species. Although we have not
attempted separation of enantiomers of any of the reported
compounds, they possess one stereogenic phosphorus center
each and as such may be of future interest for asymmetric
synthesis/catalysis.
1
2
112.8 (dd, JCP = 49.8 Hz, JCP = 5.2 Hz, Ph q-C), 123.2−123.6 (m,
2
2
C3/C7), 125.4−125.9 (m, C5), 126.6 (dd, JCP = 26.0 Hz, JCP = 6.6
Hz, C10), 129.5 (d, 1JCP = 47.1 Hz, C1), 130.6−130.9 (m, o-Ph CH),
2
132.7−132.9 (m, o-Ph CH), 135.1 (d, JCP = 4.6 Hz, C8), 135.4 (d,
2JCP = 4.6 Hz, C2), 135.8 (d, 2JCP = 8.4 Hz, m-Ph CH), 136.2 (d, 2JCP
= 8.6 Hz, m-Ph CH), 136.9 (s, p-Ph CH), 139.7−142.0 (m, C9), 151.1
(s, C4 or C6), 156.1 (s, C4 or C6). 31P{1H} NMR (109.4 MHz,
We have previously reported the synthesis of peri-substituted
phosphino-phosphonium salts by methylation of the diphos-
1
CD3CN): δ −34.5 (d, PhP), 60.0 (d, iPr2P), JPP = 303 Hz. Raman
26
(glass capillary, cm−1): ν 3057 (s), 2930 (br, νC−H), 1607 (s), 1582 (s),
1444 (s), 1416 (s), 1386 (s), 996 (s), 595 (m), 407 (m), 260 (m). IR
(KBr disk, cm−1): ν 1609 (m), 1458 (m), 1437 (m), 1397 (m), 1259
(m), 1148 (m), 1084 (m), 1038 (m), 857 (m), 750 (m), 699 (m). MS
phine Nap(PhP)2 (Nap = naphthalene-1,8-diyl). However,
the synthesis of diphosphines such as Nap(PhP)2 is nontrivial
and we have encountered great difficulties extending it toward
other derivatives. The route to the same family of phosphino-
phosphonium salts presented here is both more convenient and
much more amenable to extending toward other derivatives
with varied electronic and steric properties.
+
(ES+): 377 (cation), 409 (cation + MeOH). HRMS for C24H27P2 :
calcd 377.1588, found 377.1596. Mp: 95−98 °C.
[Acenap(PiPr2)(PFc)]+Cl−, Phosphino-Phosphonium Chloride
3. nBuLi (3.4 mL of 2.5 M solution in hexanes, 8.58 mmol) was added
dropwise to 1 (3.0 g, 8.58 mmol) in diethyl ether (60 mL) at −78 °C.
The mixture was stirred at −78 °C for 2 h. A suspension of FcPCl2
(2.46 g, 8.58 mmol) in diethyl ether (40 mL) was added dropwise at
−78 °C. The resulting pale orange suspension was stirred at −78 °C
for 2 h before it was warmed to room temperature slowly and stirred
EXPERIMENTAL SECTION
General Procedures. All experiments were carried out in standard
Schlenk glassware. Solvents were dried on an MBraun solvent
purification system and stored over molecular sieves prior to use. 5-
■
H
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2
for 16 h. Solvent was removed in vacuo to give an orange solid, which
was dissolved in CH2Cl2 (50 mL) and washed with degassed water (10
mL). The organic layer was separated, and solvent was removed in
vacuo to give 3 as an orange solid (4.38 g, 98% yield). Analytically
pure material was obtained by slow addition of toluene to a
concentrated solution of 3 in 1,2-dichloroethane to give an orange
precipitate, which was collected by filtration and dried in vacuo.
Orange needle-shaped crystals of 3 suitable for X-ray crystallography
were grown from MeCN at 2 °C. Anal. Calcd for C28H31ClFeP2: C,
22.2−22.5 (m, iPr CH3), 22.7 (d, JCP = 5.0 Hz, iPr CH3), 24.3−24.5
(m, iPr2P iPr CH), 24.7−24.8 (m, iPrP iPr CH), 25.0−25.2 (m, iPr2P
iPr CH), 31.4 (s, CH2), 32.1 (s, CH2), 122.7−123.0 (m, C3 and C7),
134.8−135.3 (m, C2), 135.8−136.0 (m, C8), 150.1 (s, C4 or C6),
156.0 (s, C4 or C6). 31P NMR (109.4 MHz, CD3CN): δ −23.0 (br d,
iPrP), 60.5 (br d, Pr2P). JPP = 306 Hz. 31P{1H} NMR (109.4 MHz,
i
1
i
i
1
CD3CN): δ −22.9 (d, PrP), 60.6 (d, Pr2P). JPP = 306 Hz. Raman
(glass capillary, cm−1): ν 3059 (m), 2933 (br s, νC−H), 1604 (m), 1569
(m), 1447 (m), 1417 (m), 1332 (s), 1168 (m), 945 (m), 821 (m), 721
(m), 646 (m), 585 (m), 265 (m). MS (ES+): 383 (cation + OH +
Na+), 743 ((cation + OH)2 + Na+). Mp: 174−178 °C.
Acenap(PiPr2)(PPhH), Bis(phosphine) 6. LiAlH4 (0.33 mL of
2.4 M solution in thf, 0.80 mmol) was added to 2 (0.73 mmol, 0.3 g)
in thf (25 mL) at 0 °C over a few minutes. The resulting mixture was
warmed to room temperature and was stirred for 2 h. Volatiles were
removed in vacuo, and CH2Cl2 (10 mL) was added. The solution was
washed with degassed H2O (2 mL), and the organic layer was
separated. Evaporation of volatiles in vacuo gave 6 as a yellow oil
1
64.57; H, 6.00. Found: C, 64.40; H, 5.89. H NMR (300.1 MHz,
CD3CN): δ 1.00−1.19 (m, 12H, 4 × iPr CH3), 2.86−3.00 (m, 1H, iPr
CH), 3.05−3.13 (m, 1H, iPr CH), 3.19−3.22 (m, 1H, PCp CH), 3.62
(s, 4H, 2 × CH2), 4.36−4.39 (m, 1H, PCp CH), 4.44 (s, 5H, Cp CH),
4.70−4.73 (m, 1H, PCp CH), 4.81−4.85 (m, 1H, PCp CH), 7.69−
7.75 (m, 1H, H7), 7.76−7.81 (m, 1H, H3), 8.16 (t, 1H, J = 8.1 Hz,
H8), 8.28 (t, 1H, J = 6.5 Hz, H2). 13C{1H} NMR (67.9 MHz,
CD3CN): δ 16.5−17.6 (m, 4 × iPr CH3), 24.4−25.6 (m, 2 × iPr CH),
31.6 (s, CH2), 32.2 (s, CH2), 66.5 (d, 1JCP = 19.5 Hz, Cp q-C), 70.8 (s,
3
1
5 × Cp CH), 71.8 (d, JCP = 5.1 Hz, PCp CH), 73.0 (s, PCp CH),
(0.236 g, 85% yield). H NMR (300.1 MHz, CDCl3): δ 0.36 (dd, J =
11.1 Hz, J = 7.0 Hz, 3H, iPr CH3), 0.89−1.00 (m, 6H, 2 × iPr CH3),
1.03−1.12 (m, 3H, iPr CH3), 1.98−2.13 (m, 2H, 2 × iPr CH), 3.33 (s,
2
2
74.9 (d, JCP = 7.8 Hz, PCp CH), 76.0 (d, JCP = 35.3 Hz, PCp CH),
113.0 (d, 1JCP = 57.1 Hz, PCp CH, C9), 123.0 (s, C3 or C7), 123.1 (s,
C3 or C7), 126.1−126.6 (m, C10), 129.5 (d, JCP = 47.4 Hz, C1), 135.7
1
5
4H, 2 × CH2), 5.65 (dd, JHP = 202 Hz, JHP = 57.6 Hz), 7.12−7.20
(m, 4H, Ar CH), 7.25−7.35 (m, 3H, Ar CH), 7.59 (dd, J = 3.1 Hz, J =
7.1 Hz, 1H, Ar CH), 7.67−7.72 (m, 1H, Ar CH). 13C{1H} NMR (75.5
MHz, CDCl3): δ 19.7−20.5 (m, 4 × iPr CH3), 25.2−25.6 (m, 2 × iPr
CH), 27.0 (s), 27.2 (s), 30.3 (s, CH2), 30.5 (s, CH2), 31.1 (d, JCP = 4.5
Hz), 119.6 (s, 3 or 7), 119.9 (s, C3 or C7), 127.7 (s, Ph CH), 128.2
(d, 2JCP = 7.0 Hz, o-Ph CH), 134.0−134.4 (m, C2 or C8), 134.7 (s, C2
(dd, 2JCP = 24.9 Hz, 3JCP = 8.2 Hz, C8), 136.6 (s, C2), 139.7 (d, 3JCP
=
11.9 Hz, C5), 150.9 (s, C4 or C6), 155.9 (s, C4 or C6). 31P{1H} NMR
1
(109.4 MHz, CD3CN): δ −36.2 (d, FcP), 54.6 (d, iPr2P), JPP = 311
Hz. Raman (glass capillary, cm−1): ν 3103 (br), 2930 (br, νC−H), 1608
(s), 1444 (s), 1417 (s), 1384 (s), 1158 (m), 1108 (vs), 596 (m), 430
(m), 338 (m), 311 (m), 255 (m). IR (KBr disc, cm−1): ν 2966 (m),
2862 (m, νC−H), 1641 (s, br), 1607 (m), 1458 (m), 1384 (m), 1263
(m), 1193 (m), 1157 (m), 1105 (m), 1023 (br, m), 824 (m), 612 (v
or C8), 140.4 (s, Ph CH), 148.7 (d, JCP = 11.0 Hz, q-C). 31P NMR
1
4
1
(121.5 MHz, CDCl3): δ −41.0 (dd, JPP = 169 Hz, JPH = 202 Hz,
+
br), 487 (m). MS (ES+): 485.1 (cation). HRMS for C28H31FeP2 :
Ph(H)P), −12.3 (m (∼d), JPP = 169 Hz, iPr2P). 31P{1H} NMR
4
calcd 485.1250, found 485.1245. Mp: 110−114 °C.
4
(121.5 MHz, CDCl3): δ −41.0 (d, Ph(H)P), −12.3 (d, iPr2P), JPP
=
[Acenap(PiPr2)(P(NMe2))]+Cl−, Phosphino-Phosphonium
Chloride 4. nBuLi (0.35 mL of a 2.5 M solution in hexanes, 0.86
mmol) was added dropwise to 1 (0.3 g, 0.86 mmol) in diethyl ether (8
mL) at −78 °C. The mixture was stirred at −78 °C for 2 h.
(Me2N)PCl2 (0.1 mL, 0.86 mmol) in diethyl ether (3 mL) was added
dropwise at −78 °C. The resulting white suspension was stirred at −78
°C for 2 h before it was warmed to room temperature slowly and
stirred for 16 h. Solvent was removed in vacuo to give a colorless oil,
which was washed with diethyl ether (10 mL) and then dissolved in
CH2Cl2 (10 mL) and filtered through a sinter using filtration aid
(Celite). The Celite/sinter was washed with CH2Cl2 (5 mL). Solvent
was removed in vacuo to give 4 as a colorless oil. The purity
established by integration from 31P NMR was ca. 77%. 31P{1H} NMR
(121.5 MHz, CDCl3): δ 36.2 (d, (Me2N)P), 66.2 (d, iPr2P), 1JPP = 412
Hz. MS (ES+): 344 (cation), 376 (M + 2O). MS (APCI+): 300.1
((cation − NMe2)22+), 301.1 (cation − NMe2 + H).
+
169 Hz. MS (ES+): 377 (M − H). HRMS for C24H27P2 : calcd
377.1588, found 377.1576.
Acenap(PiPr2)(PFcH), Bis(phosphine) 7. LiAlH4 (3.85 mL of 2.4
M solution, 9.23 mmol) was added to 3 (7.10 mmol, 3.46 g) in thf
(100 mL) at 0 °C over a few minutes. The resulting suspension was
warmed to room temperature and stirred for 2 h. Solvent was removed
in vacuo, and CH2Cl2 (100 mL) was added. The solution was washed
with degassed H2O (20 mL) after slow addition at 0 °C, and the
organic layer was separated. Removal of volatiles in vacuo gave 7 as an
orange solid (3.06 g, 89% yield) of sufficient purity for further
synthesis. Yellow needle-shaped crystals suitable for X-ray crystallog-
raphy were obtained from concentrated solutions in hexane at 2 °C.
1H NMR (300.1 MHz, CDCl3): δ 0.88 (dd, 3H, 7.0 Hz, iPr CH3), 1.08
(dd, 3H, J = 5.8 Hz, J = 6.9 Hz, iPr CH3), 1.21 (m, 6H, 2 × iPr CH3),
2.24 (m, 2H, 2 × iPr CH), 3.28−3.40 (m, 4H, 2 × CH2), 4.16−4.18
(m, 1H, PCp CH), 4.25 (s, 5H, Cp CH), 4.27−4.33 (m, 2H, PCp
[Acenap(PiPr2)(PiPr)]+Cl−, Phosphino-Phosphonium Chlor-
ide 5. nBuLi (0.35 mL of 2.5 M solution in hexanes, 0.86 mmol)
was added to 1 (0.3 g, 0.86 mmol) in diethyl ether (10 mL) at −78 °C.
The mixture was stirred at −78 °C for 2 h. The resulting suspension
was warmed to 0 °C and added to iPrPCl2 (0.32 mL, 2.58 mmol) in
diethyl ether (3 mL) at −78 °C over a few minutes. The mixture was
warmed to room temperature and stirred for 16 h. Volatiles were
removed in vacuo, the resulting pale yellow oil was dissolved in
CH2Cl2 (5 mL) and washed with degassed H2O (1 mL), and the
organic layer was separated. Volatiles were removed in vacuo to give a
pale yellow oil, which was triturated with hexane (5 mL) to give 5 as a
white solid (0.307 g, 94% yield). Analytically pure material was
obtained by recrystallization from MeCN at 2 °C. Anal. Calcd for
1
5
CH), 4.60−4.63 (m, 1H, PCp CH), 5.65 (dd, JHP = 237 Hz, JHP
=
33.2 Hz, 1H, PH), 7.13 (d, 1H, J = 7.15 Hz, H7), 7.30 (d, 1H, J = 7.2
Hz, H3), 7.54 (t, 1H, J = 6.6 Hz, H8), 7.68 (dd, 1H, J = 3.2 Hz, J = 4.0
Hz, H2). 13C{1H} NMR (75.5 MHz, CDCl3): δ 19.9−20.5 (m, iPr
CH3), 20.7 (d, 2JCP = 12.2 Hz, iPr CH3), 26.1−26.6 (m, iPr CH), 30.1
(s, CH2), 30.5 (s, CH2), 69.5 (s, 5 × Cp CH), 70.5 (d, 2JCP = 7.0 Hz,
2
PCp CH), 70.7 (s, PCp CH), 75.0 (d, JCP = 7.9 Hz, PCp CH), 75.5
3
(d, JCP = 4.8 Hz, PCp CH), 119.3 (s, C7), 119.6 (s, C3), 134.5 (s,
C8), 137.0 (s, C2), 147.4 (s, C4 or C6), 148.6 (s, C4 or C6). 31P
4
1
NMR (109.4 MHz, CDCl3): δ −51.9 (dd, JPP = 199 Hz, JPH = 237
Hz, Fc(H)P), −9.4 (m (∼d), JPP = 199 Hz, iPr2P).31P{1H} NMR
4
4
(109.4 MHz, CDCl3): δ −51.9 (d, Fc(H)P), −9.3 (d, iPr2P), JPP
=
1
C21H29ClP2: C, 66.58; H, 7.72. Found: C, 66.69; H, 7.82. H NMR
199 Hz. Raman (capillary tube, cm−1): ν 3110 (m), 2935 (br s, νC−H),
2318 (m, νP−H), 1609 (m), 1566 (m), 1418 (m), 1325 (s), 1165 (m),
1108 (s), 585 (m), 315 (m). IR (KBr disc, cm−1): ν 3038 (m), 2928
(m), 2840 (m, νC−H), 2374 (m, νP−H), 1606 (m), 1459 (m), 1383 (m),
1263 (m), 1216 (m), 1156 (m), 1105 (m), 1032 (s), 822 (m), 486 (s).
MS (ES+): 485 (M − H). APCI: 271.1610 (C12H9PiPr2 + H),
287.1559 (C12H9P(O)iPr2 + H), 443.0771 (M − iPr), 487.1394 (M
(300.1 MHz, CD3CN): δ 1.02 (dd, 3H, 3JHP = 18.7 Hz, 3JHH = 9.0 Hz,
iPr CH3), 1.21−1.39 (m, 12H, iPr CH3), 1.60 (dd, 3H, 3JHP = 18.1 Hz,
3JHH = 9.0 Hz, iPr CH3), 2.62−2.77 (m, 1H, iPr2P iPr CH), 3.15−3.29
(m, 1H, iPrP iPr CH), 3.32−3.39 (m, 1H, iPr2P iPr CH), 3.48−3.59
(m, 4H, 2 × CH2), 7.53−7.61 (m, 1H, H3), 7.67−7.74 (m, 1H, H7),
7.90−7.96 (m, 1H, H2), 8.24−8.31 (m, 1H, H8). 13C{1H} NMR (75.5
MHz, CD3CN): δ 16.7−17.0 (m, iPr CH3), 18.0 (d, 2JCP = 4.0 Hz, iPr
+
+ H). HRMS for C28H33FeP2 : calcd 487.1401, found 487.1394. Mp:
2
CH3), 18.30 (d, JCP = 2.7 Hz, iPr CH3), 20.5−20.9 (m, iPr CH3),
133−138 °C.
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[(6)PtCl2], Complex 8. 6 (0.18 g, 0.44 mmol) in CH2Cl2 (5 mL)
was added to PtCl2(cod) (0.16 g, 0.44 mmol) in CH2Cl2 (15 mL) at
room temperature. After the mixture was stirred for 2 h, volatiles were
removed in vacuo to give 8 as a white solid in quantitative yield (0.284
g). Colorless, air-stable, oblong crystals suitable for X-ray crystallog-
raphy were grown from CH2Cl2 and diethyl ether at 2 °C. Anal. Calcd
give 11 as a dark brown-orange oil (60% purity by 31P NMR). 31P{1H}
NMR (121.5 MHz, CD3CN): δ 33.2 (d, Fc(Me)P), 45.9 (d, iPr2P),
1JPP = 45.3 Hz. 31P NMR (121.5 MHz, CD3CN): δ 33.2 (br m
Fc(Me)P), 45.9 (br m, iPr2P).
Acenap(PiPr2)(PPhMe), Bis(phosphine) 12. LiAlH4 solution
(0.80 mL of 2.4 M solution in thf, 1.92 mmol) diluted with thf (5 mL)
was added dropwise to 10 (obtained in the above procedure,
approximately 0.45 mmol) at 0 °C. The resulting mixture was stirred
at 0 °C for 10 min and then warmed to room temperature and stirred
for a further 30 min to give a pale yellow solution. Volatiles were
removed in vacuo, and CH2Cl2 (5 mL) was added. The resulting
solution was washed with degassed H2O (2 mL), separated, and
filtered through a sinter using filtration aid (Celite), which was then
washed with CH2Cl2 (2 × 5 mL). Volatiles were removed in vacuo to
give 12 as a yellow oil. 31P NMR spectra indicated complete
conversion of 10 to 12; hence, the resulting oil was of approximately
70% purity. 31P{1H} NMR (121.5 MHz, CDCl3): δ −35.4 (d,
1
for C24H28Cl2P2Pt: C, 44.75; H, 4.38. Found: C, 44.64; H, 4.26. H
NMR (400.1 MHz, CD2Cl2): δ 0.58 (dd, 3H, J = 8.4 Hz, J = 7.0 Hz,
iPr CH3), 0.78 (dd, 3H, J = 8.5 Hz, J = 7.0 Hz, iPr CH3), 1.11−1.17
(m, 3H, iPr CH3), 1.48 (dd, 3H, J = 9.0 Hz, J = 7.0 Hz, iPr CH3),
2.77−2.88 (m, 1H, iPr CH), 3.47−3.63 (m, 4H, 2 × CH2), 3.71−3.81
1
3
(m, 1H, iPr CH), 6.53 (m (∼dt), 1H, JHP = 451 Hz, JHP = 21.0 Hz,
PH), 7.17−7.26 (m, 4H, Ph CH), 7.29−7.35 (m, 1H, H3 or H7),
7.52−7.57 (m, 2H, H3 or H7 and Ph CH), 7.90−7.95 (m, 1H, H8),
8.02 (dd, 1H, J = 8.0 Hz, J = 7.1 Hz, H2). 31P NMR (162.0 MHz,
1
1
CD2Cl2): δ −20.9 (m with satellites, JPH = 451 Hz, JPPt = 3212 Hz,
Ph(H)P), 14.8 (m with satellites, JPPt = 3397 Hz, iPr2P). 31P{1H}
1
2
4
Ph(Me)P), −8.5 (d, iPr2P), JPP = 169 Hz. 31P NMR (121.5 MHz,
NMR (162.0 MHz, CD2Cl2): δ −20.9 (d with satellites, JPP = 25.4
1
2
Hz, JPPt = 3212 Hz, Ph(H)P), 14.8 (d with satellites, JPP = 25.4 Hz,
1JPPt = 3397 Hz, iPr2P). 195Pt{1H} NMR (58.1 MHz, CD2Cl2): δ
CDCl3): δ −35.4 (br m (∼d), Ph(Me)P), −8.5 (br m (∼d), iPr2P),
4JPP = 169 Hz.
−4504 (dd, JPtP = 3403 Hz, JPtP = 3220 Hz). 13C{1H} NMR (75.5
MHz, CD2Cl2): δ 17.2 (d, 3JCP = 6.0 Hz, iPr CH3), 19.3−19.8 (m, 3 ×
iPr CH3), 27.0 (d, 1JCP = 34.7 Hz, iPr CH), 28.8 (d, 1JCP = 36.3 Hz, iPr
CH), 31.2 (s, CH2), 31.5 (s, CH2), 120.3 (d, 3JCP = 9.0 Hz, C3 or C7),
1
1
Acenap(PiPr2)(PFcMe), Bis(phosphine) 13. LiAlH4 solution
(0.70 mL of 2.4 M solution in thf, 1.65 mmol) was diluted with thf
(5 mL) and added dropwise to 11 (obtained in the above procedure,
approximately 0.38 mmol) at 0 °C. The resulting mixture was stirred
at 0 °C for 10 min and then warmed to room temperature and stirred
for a further 30 min to give an orange solution. Volatiles were removed
in vacuo, and CH2Cl2 (5 mL) was added. The resulting solution was
washed with degassed H2O (1 mL), separated, and filtered through a
sinter using filtration aid (Celite), which was then washed with
CH2Cl2 (2 × 5 mL). Volatiles were removed in vacuo to give 13 as an
orange oil. NMR spectra indicated complete conversion of 11 to 13;
hence, the resulting oil was of approximately 60% purity. 31P{1H}
NMR (121.5 MHz, CDCl3): δ −47.4 (d, Fc(Me)P), −5.2 (d, iPr2P),
4JPP = 163 Hz. 31P NMR (121.5 MHz, CDCl3): δ −47.4 (br m (∼d),
3
121.3 (d, JCP = 11.0 Hz, C3 or C7), 129.3 (s, Ph CH), 129.4 (s, Ph
CH), 132.0 (d, JCP = 2.9 Hz, Ph p-CH), 133.2 (s, Ph CH), 133.3 (s, Ph
2
CH) 135.1 (d, JCP = 3.2 Hz, C8), 139.0 (d, JCP = 6.4 Hz, C2) 154.0
(s, C4 or C6), 154.8 (s, C4 or C6). Raman (glass capillary, cm−1): ν
3063 (s), 2957 (m), 2917 (vs, νC−H), 2386 (m, νP−H), 1601 (m), 1588
(m), 1571 (m), 1443 (s), 1421 (m), 1343 (s), 1001 (m), 307 (m). IR
(KBr disk, cm−1): ν 2963 (m), 2926 (m, νC−H), 1596 (m), 1438 (m),
1261 (s), 1096 (s), 1024 (s), 802 (s). MS (ES+): 608 (M − Cl), 572
(M − HCl − Cl); correct isotopic patterns were observed for these
peaks. Mp: 134−138 °C.
[(7)PtCl2], Complex 9. 7 (0.3 g, 0.62 mmol) in CH2Cl2 (13 mL)
was added to PtCl2(cod) (0.23 g, 0.62 mmol) in CH2Cl2 (2 mL) at
room temperature. After the mixture was stirred for 16 h, the volatiles
were removed in vacuo to give 9 as an orange solid in quantitative
yield (0.466 g). Orange, oblong crystals suitable for X-ray
crystallography were grown from MeCN at 2 °C. Anal. Calcd for
4
Fc(Me)P), −5.1 (br m (∼d), iPr2P), JPP = 162.1 Hz.
[(12)Mo(CO)4], Complex 14. 12 (obtained in the above
procedure, approximately 0.44 mmol) in CH2Cl2 (10 mL) was
added to [(nor)Mo(CO)4] (0.13 g, 0.44 mmol) in CH2Cl2 (1 mL) at
room temperature. The resulting brown suspension was stirred for 16
h and then filtered through a sinter using filtration aid (Celite), which
was subsequently washed with CH2Cl2 (2 × 5 mL). Volatiles were
removed from the resulting brown solution in vacuo to give crude 14
as a brown oil. Crude material was recrystallized from MeCN at 2 °C
to give air-stable, analytically pure 14 as light brown crystals (61 mg,
23% yield). Some of the cube-shaped crystals were suitable for X-ray
crystallography. Anal. Calcd for C29H30MoO4P2: C, 58.01; H, 5.04.
1
C28H32Cl2FeP2Pt: C, 44.70; H, 4.29. Found: C, 44.85; H, 4.36. H
NMR (270.2 MHz, CD2Cl2): δ 0.60−0.81 (br m, 3H, iPr CH3), 1.03−
1.55 (br m, 9H, iPr CH3), 1.63−1.85 (br m, 1H, iPr CH), 3.48−3.61
(br m, 4H, 2 × CH2), 3.63−3.74 (br m, 1H, iPr CH), 3.92−5.14 (br
m, 9H, FcH), 6.97 (m (∼d), 1H, PH), 7.24−7.69 (br m, 3H, Ar CH),
7.81−8.26 (br m, 1H, Ar CH). 31P NMR (121.5 MHz, CD2Cl2): δ
1
1
−17.4 (m (∼d), JPH = 468 Hz, JPPt = 3159 Hz, Fc(H)P), 14.7 (m,
1
1JPPt = 3456 Hz, iPr2P). 31P{1H} NMR (121.5 MHz, CD2Cl2): δ −17.4
(d with satellites, JPP = 25.6 Hz, JPPt = 3159 Hz, Fc(H)P), 14.6 (d
Found: C, 57.94; H, 5.08. H NMR (300.1 MHz, CDCl3): δ 0.80−
2
1
1.01 (m, 6H, 2 × iPr CH3), 1.04−1.18 (m, 6H, 2 × iPr CH3), 2.15 (d,
3H, 2JHP = 4.7 Hz, P-Me), 2.40−2.54 (m, 1H, iPr CH), 3.41 (s, 4H, 2
× CH2), 7.22−7.32 (m, 6H, C7 and Ph CH), 7.37 (d, 1H, J = 7.3 Hz,
H3), 7.64−7.72 (m, 1H, H2), 7.78 (t, 1H, J = 7.5 Hz, H8). 13C{1H}
NMR (75.5 MHz, CDCl3): δ 18.6−19.2 (m, 4 × iPr CH3), 24.8 (dd,
2
1
with satellites, JPP = 25.6 Hz, JPPt = 3456 Hz, iPr2P). Raman (glass
capillary, cm−1): ν 3102 (m), 2926 (s), 1603 (m), 1571 (m), 1541
(m), 1442 (m), 1416 (m), 1337 (m), 1153 (m), 1109 (s), 887 (m),
828 (m), 730 (m), 587 (m), 446 (m), 324 (s), 239 (m). IR (KBr disk,
cm−1): ν 2962 (m), 2926 (m), 2374 (m, νP−H), 1602 (s), 1459 (br,
m), 1258 (m), 1034 (br, s), 538 (br, s). MS (ES+): 680.1 (M − HCl −
Cl). HRMS for C28H31FeP2Pt+: calcd 680.0898, found 680.0893. Mp:
185−190 °C.
1JCP = 24.1 Hz, 3JCP = 3.2 Hz, P-CH3), 29.3 (dd, 1JCP = 16.1 Hz, 3JCP
=
3.3 Hz, 2 × iPr CH), 30.2 (s, CH2), 30.4 (s, CH2), 119.2 (d, 3JCP = 5.2
Hz, C7), 119.7 (d, 3JCP = 6.0 Hz, C3), 123.8 (dd, 3JCP = 21.7 Hz, 3JCP
2
2
= 5.2 Hz, C5), 124.9 (dd, JCP = 30.0 Hz, JCP = 3.0 Hz, C10), 128.4
(d, JCP = 9.0 Hz, o- or m-Ph CH), 128.8 (s, p-Ph CH), 130.5 (d, JCP
[Acenap(PiPr2)(PPhMe)]2+(TfO−)2, 1,2-Diphosphonium 10.
MeOTf (2.0 mL, 17.67 mmol) and 2 (0.2 g, 0.48 mmol) were heated
to 90 °C for 4 h. Volatiles (including excess MeOTf) were removed in
vacuo at 50 °C to give 10 as a pale yellow oil (70% purity by 31P
NMR). 31P{1H} NMR (121.5 MHz, CD3CN): δ 31.0 (d, Ph(Me)P),
=
11.2 Hz, o- or m-Ph CH), 133.5 (s, C8), 136.4 (s, C2), 140.9−141.2
1
(m, C1), 143.1 (d, JCP = 32.7 Hz, Ph i-C), 150.6 (s, C6), 151.9 (s,
C4). 31P{1H} NMR (121.5 MHz, CDCl3): δ 8.6 (d, Ph(Me)P), 42.9
2
(d, iPr2P), JPP = 35.1 Hz. 31P NMR (121.5 MHz, CDCl3): δ 8.6 (br
m, Ph(Me)P), 42.9 (br m, iPr2P). Raman (glass capillary, cm−1): ν
3068 (m), 2925 (s, νC−H), 2010 (m), 1909 (s, νC−O), 1878 (s, νC−O),
1608 (m), 1591 (m), 1566 (m), 1445 (m), 1417 (m), 1322 (m), 1001
(m), 585 (m), 455 (s), 417 (m). IR (KBr disk, cm−1): ν 2931 (m,
νC−H), 2013 (m), 1897 (vs, νC−O), 1603 (m), 1439 (m), 1260 (m),
1136 (s), 1033 (s), 958 (m), 747 (m), 696 (m). MS (CI+): 602.1
(M+), 573.1 (M+ − CO), 547.1 (M+ − 2 CO), 518.1 (M+ − 3 CO),
271.2 (C12H9PiPr2+H+), 349.1 (C12H8PiPrPPhMe, base peak), 393.2
1
52.8 (d, iPr2P), JPP = 27.6 Hz. 31P NMR (121.5 MHz, CD3CN): δ
31.0 (br m, Ph(Me)P), 52.8 (br m, iPr2P). MS (ES+): 409 (dication +
O + H, hydrolysis product), MS (ES−): 149 (TfO), 299 ([(TfO)2H]),
321 ([(TfO)2Na]).
[Acenap(PiPr2)(PFcMe)]2+(TfO−)2, 1,2-Diphosphonium 11.
MeOTf (2 mL, 17.67 mmol) and 3 (0.2 g, 0.38 mmol) were heated
to 90 °C for 4 h. On heating an orange precipitate forms and the color
of the solution darkens. Volatiles were removed in vacuo at 50 °C to
J
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(C12H8PiPr2PMePh+H+); correct isotopic patterns were observed for
all peaks. Mp: 135−139 °C.
(2) For a review of phospheniums see: Multiple Bonds and Low
Coordination in Phosphorus Chemistry; Regitz, M., Scherer, O. J., Eds.;
Georg Thieme Verlag: Stuttgart, Germany, 1990; pp 129−148.
(3) (a) Kopp, R. W.; Bond, A. C.; Parry, R. W. Inorg. Chem. 1976, 15,
3042−3046. (b) Schultz, C. W.; Parry, R. W. Inorg. Chem. 1976, 15,
3046−3050.
[(13)Mo(CO)4], Complex 15. 13 (obtained in the above
procedure, approximately 0.35 mmol) in CH2Cl2 (10 mL) was
added to [(nor)Mo(CO)4] (0.11 g, 0.35 mmol) in CH2Cl2 (2 mL) at
room temperature. The resulting dark brown suspension was stirred
for 16 h and then filtered through a sinter using filtration aid (Celite),
which was subsequently washed with CH2Cl2 (2 × 5 mL). Volatiles
were removed from the resulting orange solution in vacuo to give
crude 15 as an orange oil. Crude material was recrystallized from
MeCN at 2 °C to give air-stable, analytically pure 15 as dark brown
crystals (57 mg, 23% yield). Some of the rod-shaped crystals were
suitable for X-ray crystallography. Anal. Calcd for C33H34FeMoO4P2:
(4) Cowley, A. H.; Lattman, M.; Wilburn, J. C. Inorg. Chem. 1981, 20,
2916−2919.
(5) Baxter, S. G.; Collins, R. L.; Cowley, A. H.; Sena, S. F. J. Am.
Chem. Soc. 1981, 103, 714−715.
(6) Baxter, S. G.; Collins, R. L.; Cowley, A. H.; Sena, S. F. Inorg.
Chem. 1983, 22, 3475−3479.
(7) Schomburg, C. Acta Crystallogr., Sect. A 1984, 40, C265.
(8) (a) Dyker, C. A.; Burford, N. Chem. Asian J. 2008, 3, 28−36.
(b) Burford, N.; Ragogna, P. J. Dalton Trans. 2002, 4307−4315.
(c) Ellis, B. D.; Macdonald, C. L. B. Coord. Chem. Rev. 2007, 251,
936−973.
1
C, 55.95; H, 4.84. Found: C, 55.74; H, 4.71. H NMR (400.1 MHz,
CDCl3): δ 0.55−0.62 (m, 3H, iPr CH3), 0.74 (dd, 3H, J = 6.1 Hz, J =
6.8 Hz, iPr CH3), 1.32 (dd, 3H, J = 8.0 Hz, J = 7.0 Hz, iPr CH3), 1.39
(dd, 3H, J = 10.0 Hz, J = 6.8 Hz, iPr CH3), 1.81 (d, 3H, 2JHP = 5.5 Hz,
P-Me), 2.16−2.24 (m, 1H, iPr CH), 2.75−2.86 (m, 1H, iPr CH),
3.37−3.44 (m, 4H, CH2), 3.94−3.96 (m, 1H, PCp CH), 4.34 (s, 5H,
Cp CH), 4.43−4.46 (m, 1H, PCp CH), 4.59−4.61 (m, 1H, PCp CH),
4.71−4.73 (m, 1H, PCp CH), 7.14 (d, 1H, 3JHH = 7.2 Hz, H3), 7.21−
7.25 (m, 1H, H2), 7.36 (d, 3JHH = 7.2 Hz, 1H, H7), 7.81 (t, J = 7.2 Hz,
1H, H8). 13C{1H} NMR (67.9 MHz, CDCl3): δ 17.9 (s, 2 × iPr CH3),
19.2−19.6 (m, 2 × iPrCH3), 21.5 (d, 1JCP = 25.7 Hz, P-CH3), 28.2 (d,
(9) Carpenter, Y.; Dyker, C. A.; Burford, N.; Lumsden, M. D.;
Decken, A. J. Am. Chem. Soc. 2008, 130, 15732−15741.
(10) Weigand, J. J.; Burford, N.; Davidson, R. J.; Cameron, T. S.;
Seelheim, P. J. Am. Chem. Soc. 2009, 131, 17943−17953.
(11) (a) Seidel, W. Z. Anorg. Allg. Chem. 1964, 330, 141−150.
(b) Spangenberg, S. F.; Sisler, H. H. Inorg. Chem. 1969, 8, 1006−1010.
(c) Summers, J. C.; Sisler, H. H. Inorg. Chem. 1970, 9, 862−869.
(12) Chitnis, S. S.; MacDonald, E.; Burford, N.; Werner-Zwanziger,
U.; McDonald, R. Chem. Commun. 2012, 48, 7359−7361.
(13) Weigand, J. J.; Riegel, S. D.; Burford, N.; Decken, A. J. Am.
Chem. Soc. 2007, 129, 7969−7976.
1JCP = 25.7 Hz, iPr CH), 30.1 (s, CH2), 30.4 (s, CH2), 35.1 (d, 1JCP
=
18.5 Hz, iPr CH), 69.7 (s, 5 × Cp CH), 70.3 (s, PCp CH), 70.8 (s,
PCp CH), 70.9 (s, PCp CH), 71.6 (d, 2JCP = 9.3 Hz, PCp CH), 119.0
3
3
(d, JCP = 4.9 Hz, C3), 119.1 (d, JCP = 6.5 Hz, C7), 132.3 (s, C2),
132.5 (s, C8), 149.2 (s, C4 or C6), 150.6 (C4 or C6). 31P{1H} NMR
(162.0 MHz, CDCl3): δ 4.5 (d, Fc(Me)P), 41.6 (d, iPr2P), 2JPP = 30.2
Hz. 31P NMR (162.0 MHz, CDCl3): δ 4.5 (br m, Fc(Me)P), 41.6 (br
(14) Burford, N.; Ragogna, P. J.; McDonald, R.; Ferguson, M. J. J.
Am. Chem. Soc. 2003, 125, 14404−14410.
m, iPr P). IR (KBr disk, cm−1): ν 2963 (s), 2857 (m, νC−H), 2009
(15) Schomburg, D.; Bettermann, G.; Ernst, L.; Schmutzler, R.
Angew. Chem., Int. Ed. Engl. 1985, 24, 975−976.
2
(m), 1894 (s, νC−O), 1719 (m), 1600 (m), 1414 (m), 1262 (vs), 1099
(vs), 801 (vs), 391 (m).
(16) Alder, R. W.; Ganter, C.; Harris, C. J.; Orpen, A. G. Chem.
Commun. 1992, 1172−1174.
(17) (a) Alder, R. W.; Ganter, C.; Gil, M.; Gleiter, R.; Harris, C. J.;
Harris, S. E.; Lange, H.; Orpen, A. G.; Taylor, P. N. J. Chem. Soc.,
Perkin Trans. 1 1998, 1643−1655. (b) Alder, R. W.; Ellis, D. D.;
Gleiter, R.; Harris, C. J.; Lange, H.; Orpen, A. G.; Read, D.; Taylor, P.
N. J. Chem. Soc., Perkin Trans. 1 1998, 1657−1668.
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ASSOCIATED CONTENT
* Supporting Information
CIF, tables, and text giving crystallographic data for 2, 3, 7, 8, 9,
14, and 15 and X-ray experimental and computational details.
This material is available free of charge via the Internet at
http://pubs.acs.org.
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S
(19) Slattery, J. M.; Fish, C.; Green, M.; Hooper, T. N.; Jeffery, J. C.;
Kilby, R. J.; Lynam, J. M.; McGrady, J. E.; Pantazis, D. A.; Russell, C.
A.; Willans, C. E. Chem. Eur. J. 2007, 13, 6967−6974.
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19, 4944−4956.
AUTHOR INFORMATION
Corresponding Author
*E-mail for P.K.: pk7@st-andrews.ac.uk.
Notes
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(21) Karacar, A.; Freytag, M.; Thoennessen, H.; Jones, P. G.; Bartsch,
R.; Schmutzler, R. J. Organomet. Chem. 2002, 643, 68−80.
(22) Van der Winkel, Y.; van der Laarse, J.; de Kanter, F. J. J.; van der
Does, T.; Bickelhaupt, F.; Smeets, W. J. J.; Spek, A. L. Heteroat. Chem.
1991, 2, 17−28.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We thank Mrs. C. E. R. Horsburgh at the University of St
Andrews and the National Mass Spectrometry Service Center
at the University of Swansea for measurement of mass spectra
and EaStChem, EPSRC, and the COST action CM0802
PhoSciNet for financial support. M.B. wishes to thank H.
(23) Kilian, P.; Slawin, A. M. Z.; Woollins, J. D. Dalton Trans. 1996,
2175−2183.
(24) Charrier, C.; Maigrot, N.; Mathey, F.; Robert, F.; Jeannin, Y.
Organometallics 1986, 5, 623−630.
(25) For recent reviews see: Kilian, P.; Knight, F. R.; Woollins, J. D.
Chem. Eur. J. 2011, 17, 2302−2328. Kilian, P.; Knight, F. R.; Woollins,
J. D. Coord. Chem. Rev. 2011, 1387−1413.
Fruchtl for technical assistance. Computations were performed
̈
on PC clusters in St Andrews and, with assistance from Dr.
Helen Tsui, at the EPSRC UK National Service for Computa-
tional Chemistry Software (NSCCS) at Imperial College
London.
(26) Somisara, D. M. U. K.; Buehl, M.; Lebl, T.; Richardson, N. V.;
Slawin, A. M. Z.; Woollins, J. D.; Kilian, P. Chem. Eur. J. 2011, 17,
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Chem. 2009, 48, 2500−2506.
(28) Ray, M. J.; Randall, R. A. M.; Athukorala Arachchige, K. S.;
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(36) These distances are in line with those observed in related
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