Ruthenium PCP-bis(phosphinite) pincer complexes

Article abstract of DOI:10.1016/j.ica.2005.07.050

The reactions of [RuHCl(CO)(PPh₃)₃] with resorcinol bis(phosphinite) pincer ligands lead to complexes of the general formula [RuCl(PCP)(CO)(PPh₃)]; the crystal structure of one example has been determined. The structures of the bulky resorcinol 2-methyl-4,6-di-tert-butyl resorcinol and its mono-diisopropylphosphinite derivative were also determined. Reactions of [RuCl₂(PPh₃)₃] with resorcinol bis(phosphinite) ligands yield complexes of the type [RuCl(PCP)(PPh ₃)], while the reaction of C₆H-2-Me-4,6- ^tBu₂-1,3-(OPPh₂) with [RuHCl(CO)(PPh ₃)₃] provides a PCP-pincer complex in which the ligand has undergone 2-methyl C-H activation.

Full text of DOI:10.1016/j.ica.2005.07.050

Inorganica Chimica Acta 359 (2006) 1870–1878
www.elsevier.com/locate/ica
Ruthenium PCP–bis(phosphinite) pincer complexes
a,
a
b
c
Robin B. Bedford *, Michael Betham , Michael E. Blake , Simon J. Coles ,
d
c
d
Sylvia M. Draper , Michael B. Hursthouse , P. Noelle Scully
a
School of Chemistry, University of Bristol, CantockÕs Close, Bristol BS8 1TS, UK
Department of Chemistry, University of Exeter, Exeter EX4 4QD, UK
b
c
EPSRC National Crystallography Service, Department of Chemistry, University of Southampton, Highfield Road, Southampton SO17 1BJ, UK
d
Department of Chemistry, Trinity College Dublin, Dublin 2, Ireland
Received 2 July 2005; accepted 20 July 2005
Available online 24 January 2006
Dedicated to Professor Gerard van Koten in recognition of his many outstanding contributions to organometallic chemistry.
Abstract
The reactions of [RuHCl(CO)(PPh3)3] with resorcinol bis(phosphinite) pincer ligands lead to complexes of the general formula
[RuCl(PCP)(CO)(PPh3)]; the crystal structure of one example has been determined. The structures of the bulky resorcinol 2-methyl-
4,6-di-tert-butyl resorcinol and its mono-diisopropylphosphinite derivative were also determined. Reactions of [RuCl2(PPh3)3] with res-
orcinol bis(phosphinite) ligands yield complexes of the type [RuCl(PCP)(PPh3)], while the reaction of C6H-2-Me-4,6-tBu2-1,3-(OPPh2)
with [RuHCl(CO)(PPh3)3] provides a PCP–pincer complex in which the ligand has undergone 2-methyl C–H activation.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Ruthenium; Pincer ligands; C–H activation; Phosphinites; Orthometallation
1. Introduction
While there is a rich chemistry associated with PCP–
ÔPCPÕ pincer complexes of the type 1 display a wide range
ruthenium complexes of the type 2 containing bis(phos-
of catalytic activity [1]. For instance palladium complexes
phine) pincer ligands, to the best of our knowledge there
have been used in coupling reactions [2] and the allylation
are no reported bis(phosphinite) analogues, 3. This is
and phenylation of aldehydes and imines [3]. Both palladium
despite the fact that bis(phosphinite) PCP-complexes have
and platinum complexes have been exploited for the asym-
been shown to be highly active catalysts for both C–C cou-
metric aldol reaction of methylisocyanate with aldehydes
pling reactions and alkane dehydrogenation [2d,2e,8].
[4]. Ruthenium complexes have been used for transfer hydro-
Therefore, we were interested to see whether such com-
genation reactions [5] and chiral versions have been employed
plexes could be synthesised and it is to this that we now
in asymmetric reactions [6], while iridium complexes prove to
turn our attention.
be active catalysts for alkane dehydrogenation reactions [7].
PR2
PR2
RuLn
PR2
O
O
PR2
RuLn
PR2
MLn
PR2
Rn
1
Rn
Rn
*
Corresponding author. Fax: +44 0117 925 1295.
3
2
E-mail address: r.bedford@bristol.ac.uk (R.B. Bedford).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.07.050

R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
1871
R1
O
O
PR3
R2
2. Results and discussion
R1
OH
2
The ligands 1a and b were prepared according to litera-
ture methods [2d,9]. We wished to investigate the effect of
increasing the steric profile of the resorcinol ring since this
may lead to faster rates of orthometallation of the resultant
ligand (vide infra). Therefore, we synthesised the 4,6-di-
tert-butyl resorcinol bis(diphenylphosphinite) and bis(di-
isopropylphosphinite) ligands 1c and d.
We previously found that the reaction of a 2-methyl-
resorcinol bis(phosphinite) ligand with palladium trifluo-
roacetate does not lead to C–H activation of the methyl
group, but rather to aromatic C–H activation at the 4-
and 6-positions of the resorcinol [10]. In order to avoid
this problem with ruthenium, we decided to block off
the 4- and 6-positions. Accordingly we synthesised the
precursor resorcinol, 2-methyl-4,6-di-tert-butyl resorcinol
(2) by the reaction of 2-methylresorcinol with tert-butanol
in the presence of phosphoric acid (Scheme 1). A crystal
structure of the diol was determined and the molecule is
shown in Fig. 1.
(i)
R1
PR3
R1
OH
2
1a: R1 = R2 = H; R3 = Ph
b: R1 = R2 = H; R3 = iPr
c: R1 = tBu; R2 = H; R3 = Ph
d: R1 = tBu; R2 = H; R3 = iPr
e: R1 = tBu; R2 = Me; R3 = Ph
(iii)
But
OH
OH
(ii)
2
But
OH
OH
The reaction of the diol 2 with two equivalents of chlo-
rodiphenylphosphine in toluene with triethylamine as base
yields the bis(phosphinite) ligand 1e. By contrast the anal-
ogous reaction with two equivalents of chlorodiisopropyl-
phosphine does not produce the desired bis(phosphinite)
1f cleanly, but rather as a mixture which also contains
the starting diol 2 and the mono-substituted product 3
(Scheme 1) in an approximately 1.5:1.5:2 ratio, respec-
tively, presumably as a consequence of the high steric pro-
files of both the diol and the chlorophosphine. When the
reaction is repeated with four equivalents of the chloro-
phosphine, the proportion of 1f increases (ratio = 3:3:1.5
for 1f, 3 and 2, respectively) but a mixture is still obtained.
Recrystallisation from diethyl ether leads to the separation
of reasonably pure mono-substituted product 3 (contains
ꢀ10% starting diol, 2). The structure was confirmed by a
single crystal X-ray analysis and the molecule of 3 is shown
in Fig. 2.
(iv)
But
But
O
O
PiPr2
PiPr2
But
But
O
PiPr2
+
OH
1f
3
Scheme 1. Synthesis of ligands. Conditions. (i) ClPR3, NEt3, toluene,
2
reflux, 18 h. (ii) tBuOH, H3PO4, r.t., 1 h. (iii) ClPPh2, toluene, NEt3,
reflux, 18 h. (iv) ClPiPr2, NEt3, toluene, reflux, 18 h.
Table 1 shows the collected 31P NMR data for the
ligands 1a–f. It is not possible, with this limited data set,
to determine how the chemical shift varies with increasing
bulk of the substituents on both the phosphine groups and
the resorcinol backbone, but it is apparent that the pertur-
bation in shift is considerably greater for the dii-
sopropylphosphino-containing ligands. The 31P NMR
spectrum of 3 shows a singlet at d 160.9 ppm, very close
to that for the bis-substituted product, 1f.
The reaction of the bis(phosphinite) ligand 1a with
[RuHCl(CO)(PPh3)3] in toluene at reflux temperature for
48 h leads to the isolation of the PCP–pincer complex 4a,
in good yield (Scheme 2).
The presence of the carbonyl ligand is indicated by IR
spectroscopy which shows a strong m(CO) at 1966 cmÀ1
.
The 31P NMR spectrum of 4a consists of a doublet at d
147.7 ppm and a triplet at 17.3 ppm, corresponding to
the pincer phosphorus donors and the triphenylphosphine
Fig. 1. Molecular structure of 2-methyl-4,6-di-tert-butylresorcinol (2).

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R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
Fig. 2. X-ray structure of phosphinite 3. A molecule of ether has been
omitted for clarity.
Table 1
31P NMR spectroscopic data for the ligands 1
R2
O
PR1
2
R3
R2
O
R2
PR1
2
˚
R1
R3
31P NMR d (ppm)
Fig. 3. Molecular structure of complex 4a. Selected bond lengths (A) and
angles (ꢁ): Ru1–C2, 2.083(3); Ru1–P1, 2.4676(10); Ru1–P2, 2.3454(10);
Ru1–P3, 2.3767(8); Ru1–C1, 1.942(4); Ru1–Cl1, 2.4399(13); P2–Ru1–P3,
155.40(3); P2–Ru1–C2, 77.69(8); P3–Ru1–C2, 77.72(8); C2–Ru1–P1,
175.21(7);C1–Ru1–Cl1, 174.42(8).
1a
1c
1e
1b
1d
1f
Ph
Ph
Ph
iPr
iPr
iPr
H
H
H
Me
H
H
112.1
115.4
114.3
149.8
139.5
159.8
tBu
tBu
H
tBu
tBu
Me
ing to the carbonyl, and 161.7 ppm, corresponding to the
orthometallated ipso-carbon. The structure of complex 4a
was confirmed by single crystal X-ray analysis and the
molecular structure is shown in Fig. 3. As can be seen
the chloride is trans to the carbonyl ligand whilst the
triphenylphosphine is trans to the orthometallated carbon,
as may be expected from electronic considerations. The
Ru1–C2 bond length is in the typical range for Ru(II)–
ÔPCPÕ–pincer complexes.
R1
OPR2
R1
O
PR2
2
2
CO
[RuHCl(CO)(PPh3)3]
Ru PPh3
toluene, Δ
Cl
R1
OPR2
R1
O
PR2
2
2
The synthetic methodology used for 4a can also be
exploited for the production of the analogous complexes
4b–d (Scheme 2) and a summary of selected spectroscopic
data for the complexes is presented in Table 2. As can be
seen the data are broadly comparable and the incorporation
of tert-butyl substituents on the resorcinol backbones has
very little impact on the resultant structures. The approxi-
mately 20 cmÀ1 lower carbonyl stretching frequency for
the bis(diisopropyl)phosphinite complexes compared with
the bis(diphenylphosphino)phosphinite analogues indicates
that the former donate greater net electron density to the
ruthenium centres, as expected.
We have previously found that the rate of orthometalla-
tion of triarylphosphite ligands at palladium is greatly
enhanced by the presence of ortho-tert-butyl groups on
the aryl rings [11]. This proves to be the case with ruthe-
nium complexes of resorcinol bis(phosphinite) pincer
ligands. The 31P NMR spectra of crude product mixtures
4a: R1 = H; R2 = Ph, 72%
b: R1 = H; R2 = iPr, 67.5%
c: R1 = tBu; R2 = Ph, 71%
d: R1 = tBu; R2 = iPr, 78%
Scheme 2. Synthesis of complexes 4.
ligand respectively, with a mutual 2JPP coupling of 14.5 Hz.
The magnitude of the coupling is consistent with the triphe-
nylphosphine residue being cis to the equivalent phosphi-
nite residues. Assuming the complex is octahedral, this
means that the phosphinite residues are trans disposed.
1
There is no sign of a hydride signal in the H NMR spec-
trum of 4a. This implies that the metallation process occurs
via the loss of H2 rather than HCl. The 13C NMR spectrum
of 4a shows two low-field peaks at 197.4 ppm, correspond-

R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
1873
Table 2
Selected spectroscopic data for the complexes 4
Complex
31P NMR d (ppm)
2JPP (Hz)
13C NMR d (ppm)
Ru–CO
m(CO) (cmÀ1
)
PCP
PPh3
17.3
Ru–C
147.7
14.5
197.4
161.7
1966
O
PPh2
CO
Ru PPh3
Cl
4a
4b
O
PPh2
PiPr2
183.5
147.7
183.6
15.4
17.4
15.5
12
13
12
201.1
198.1
201.2
162.6
156.9
167.6
1943,1924 (sh)
O
CO
Ru PPh3
Cl
O
PiPr2
But
O
PPh2
CO
1969
Ru PPh3
Cl
But
But
O
PPh2
4c
4d
PiPr2
1945, 1923(sh)
O
CO
Ru PPh3
Cl
But
O
PiPr2
from the reactions of [RuHCl(CO)(PPh3)3] with the
bis(diphenylphosphinite) ligands 1a and c at 80 ꢁC in tolu-
ene for 24 h show that the complexes 4a and c are formed
in approximately 16.5% and 73%, respectively (versus tri-
phenylphosphine oxide internal standard). In both cases
the spectra are not clean but show significant amounts of
other species.
the ligands 1c and d (Scheme 2) in toluene at reflux temper-
ature overnight. The complexes 5a and b are produced
under these conditions, but we were unable to separate
the products from the triphenylphosphine produced, due
to their high solubility in all solvents tested.1 The 31P
NMR spectrum of complex 5b shows a doublet at
146.7 ppm and a triplet at 81.6 ppm corresponding to the
pincer ligand and coordinated triphenylphosphine, respec-
tively. In this case the resonance for the pincer ligand is
very similar to that of the carbonyl complex 4c, but a large
(64.2 ppm) downfield shift is still observed for the triphe-
nylphosphine ligand compared with that of 4c. Again there
Interestingly, in the reaction of [RuHCl(CO)(PPh3)3]
with the bulky bis(diisopropyl)phosphinite pincer ligand
1d in toluene at reflux temperature, the 31P NMR spectrum
of a crude product mixture shows the presence of reason-
able amounts of a second product (ꢀ10%). This species
is typified by a doublet at 170.8 ppm for the pincer ligand
and a triplet at 76.8 ppm corresponding to a triphenyl-
phosphine ligand, with a mutual coupling of 33 Hz. The
phosphinite peak is shifted 12.8 ppm upfield compared
with that of complex 4d whilst the triphenylphosphine
2
is a substantial increase in the JPP of complex 5b (34 Hz)
compared with that of 4c. The smaller shift difference of
the pincer ligands compared with the phosphine ligands
on decarbonylation is perhaps not surprising, given that
the coordination mode of the pincer would remain largely
unaffected by the change in geometry from octahedral to
trigonal bipyramidal.
In order to try to establish a cleaner synthesis of com-
plexes of the type 5, we investigated the possibility of
using [{RuCl2(p-cymene)}2] as the ruthenium precursor
in the presence of one equivalent each of ligand 1c and
2
peak is shifted 61.4 ppm downfield. In addition the JPP
is 2.75 times larger than that in complex 4d. Taken
together, the data indicate a substantial electronic differ-
ence between complex 4d and the minor species. It seemed
plausible to us that the second species could be the decarb-
onylation product, complex 5a (Scheme 3), therefore we
next attempted to synthesise genuine examples of com-
plexes of the type 5 via alternate routes. In the first
instance we examined the reactions of [RuCl2(PPh3)3] with
1
Milstein and co-workers experience similar problems with bis(diiso-
propyl)phosphine Ru(II) pincer complexes: see ref. [14].

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R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
But
But
O
PiPr2
CO
But
O
PiPr2
Cl
- CO
(i)
Ru PPh3
Ru
PPh3
PiPr2
Cl
PiPr2
But
O
O
4d
5a
vacuum
+
But
But
O
PiPr2
Py
But
OPR2
OPR2
But
But
O
O
PiPr2
(iii)
Cl
Ru
Py
PiPr2
Ru Py
R = iPr
Cl
PiPr2
But
O
7
Py
8
R = Ph, iPr
(ii)
But
But
O
PR2
Cl
Ru
+ 2 PPh3
PPh3
O
PR2
intractable mixtures
5a: R = iPr
b: R = Ph
Scheme 3. Conditions. (i) Toluene, D. (ii) [RuCl2(PPh3)3], toluene, D, 18 h. (iii) [RuCl2(NBD)(Py)2], toluene, D, 18 h.
triphenylphosphine in toluene at reflux temperature over-
night. Unfortunately, this gave a mixture of products as
determined by 31P NMR spectroscopy, none of which is
the desired complex. As an alternative we next heated a
mixture of [{RuCl2(NBD)}2] and 1c in toluene at reflux
temperature, but no reaction was observed. Bergens
and co-workers recently demonstrated that the pyridine-
containing complex [RuCl2(NBD)(Py)2] (6) reacts with
chelating bisphosphines to give the complexes
[RuCl2(py)2(bisphosphine)] [12]. We therefore wondered
whether this would make a good precursor to PCP–pin-
cer complexes. Complex 6 was heated in toluene with
ligand 1d overnight to give a mixture of two products
assigned as the mono (major) and bis-pyridine (minor)
complexes 7 and 8 (Scheme 3), on the basis of their
NMR data. The 31P NMR spectrum shows a singlet
173.3 ppm for complex 7 and another at 187.8 ppm for
the labile nature of at least one of the pyridine ligands in
8, we imagined that treatment of a mixture of 7 and 8
with triphenylphosphine would yield complex 5a. How-
ever, when this is attempted at room temperature in tol-
uene solution, 31P NMR spectroscopy revealed that only
a very small quantity of 5a is produced. Even on heating
at reflux in toluene overnight, substantial amounts of the
starting material 7 and triphenylphosphine persist. Inter-
estingly, the peak at 187.8 ppm corresponding to com-
plex 8 almost completely disappears and is replaced by
another singlet at 194.5 ppm. This latter peak may corre-
spond to a second isomer of 8.
The reaction of complex 6 with the PCP ligand 1d leads
to a mixture of several complexes as determined by 31P
NMR spectroscopy. Two singlets are seen at d 172.0 and
157.3 ppm, which are tentatively assigned as the mono-
and bis-pyridine complexes 7b and 8b. These signals are
15.6 and 16.0 ppm, respectively, downfield of the equiva-
lent signals for the complexes 7a and 8a. A downfield shift
on substitution of PiPr2 with PPh2 donors is consistent with
the data obtained for the complexes 4. Further, the differ-
ence in shift between 7b and 8b (14.9 ppm) is very close
to that between 7a and 8a (14.5 ppm). In addition to these
complexes, two other major species are observed which are
tentatively assigned as isomers of di-ruthenium complexes
which contain two ÔPCP–RuÕ fragments that are bridged
1
complex 8. The H NMR signals associated with the pyr-
idine ring of the mono-pyridine adduct 7 are somewhat
sharper than those of the bis-pyridine adduct 8, implying
that one of the pyridine ligands in the latter complex
may be labile. Indeed, when the mixture is held under
vacuum for 12 h, the proportion of 7 in the mixture
increases slightly. Addition of excess pyridine to a CDCl3
solution of the mixture leads to the almost complete con-
version of complex 7 to the bis-pyridine adduct 8. Given

R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
1875
PiPr2
PPh3
PiPr2
by a third, non-C–H activated ÔPCHPÕ pincer ligand. The
first isomer shows a doublet at d 150.5 ppm and a triplet
at 107.1 ppm with a mutual coupling constant of 38.9 Hz,
PPh3
Ru
Ru
Cl
PiPr2
Cl
whilst the second species displays a doublet at
d
PiPr2
149.7 ppm and a triplet at 41.2 ppm with a coupling of
37.7 Hz. Van Koten and co-workers have shown that
related bimetallic PCP–ruthenium species with bridging
ÔPCHPÕ ligands are formed as intermediates in the synthesis
of mononuclear bis(diphenylphosphine) PCP complexes
[13].
10
11
In conclusion, we have shown that resorcinolbis(phos-
phinite) ligands readily form ruthenium PCP–pincer com-
plexes, particularly when steric bulk is introduced onto
the resorcinol backbone, in which case the rate of C–H
activation is significantly accelerated. We are currently
investigating the application of the resultant ruthenium
complexes in a range of catalytic reactions and these results
will be published at a later date.
But
O
PiPr2
But
O
PiPr2
Py
Cl
Ru
Ru Py
Py
PiPr2
Cl
But
O
But
O
PiPr2
7b
8b
3. Experimental
Finally, we examined the possibility of producing a
bis(phosphinite) pincer complex by the activation of an
alkyl rather than an aryl C–H bond. This was achieved
in a straight-forward manner by the reaction of [RuHCl-
(CO)(PPh3)3] with ligand 1e to give the complex 9
(Scheme 4). The 31P NMR spectrum of 9 shows a doublet
at 147.3 and a triplet at 17.3 ppm with a mutual coupling
constant of 13.4 Hz for the ÔPCPÕ pincer and the triphe-
nylphosphine ligands, respectively. The PCP pincer reso-
nance is remarkably close to those for the complexes 4a
and c in which aromatic C–H activation has occurred;
consistent with the data obtained by Milstein and co-
workers for the related bis(diisopropyl)phosphine PCP–
3.1. General
All reactions were performed under a nitrogen atmo-
sphere either in a glove-box or using standard Schlenk
techniques. Solvents were distilled prior to use from
appropriate drying agents. Ligands 1a and b and 4,6-
di-tert-butylresorcinol were made according to literature
procedures [2d,9,15]. All other reagents were purchased
from commercial sources and used as received.
3.1.1. Synthesis of 2-methyl-4,6-di-tert-butylresorcinol (2)
2-Methyl resorcinol (25.2 g, 203 mmol), phosphoric acid
(50 ml) and tert-butanol (39.4 g, 531 mmol) were vigorously
stirred at 60 ꢁC for 1 h. The solution was cooled to room
temperature and water (500 ml) was added to complete pre-
cipitation of the product. The product was collected by fil-
tration and washed with water (2 · 100 ml) and then
aqueous methanol (2:1, 2 · 100 ml). The crude product
was recrystallised from methanol and dried in vacuo to give
2 as a white solid. Yield: 39.4 g (82%). Crystals suitable for
X-ray analysis were obtained by recrystallisation from a
concentrated methanol solution of 2 at 0 ꢁC. Anal. Calc.
for C14H24O2: C, 75.0; H, 10.8. Found: C, 74.7; H, 11.1%.
1H NMR (CDCl3, 300 MHz): d 1.32 (s, 18H, C(CH3)3),
2.05 (s, 3H, Ar-CH3), 4.66 (s, 2H, Ar-OH), 6.98 (s, 1H,
Ar-H). 13C NMR (CDCl3, 75.5 MHz): d 8.84 (s, Ar-CH3),
30.41 (s, C(CH3)3), 34.62 (s, C(CH3)3), 110.86 (s, Ar C),
122.42 (s, Ar CH), 127.19 (s, Ar C), 151.28 (s, Ar C).
1
pincer complexes 10 and 11 [14]. The H NMR spectrum
3
shows a broad doublet at 3.08 ppm with a JPP of 12 Hz
corresponding to the metallated methylene group. The
shift is similar to that observed by Milstein and co-work-
ers for complex 11 (3.28 ppm) [14]. The half-height width
of each half of the doublet indicates that cis coupling to
the phosphinite residues must be less than 7 Hz, therefore
the 12 Hz coupling to the triphenylphosphine confirms
that this ligand is trans to the metallated methylene.
The IR spectrum of complex 9 shows a m(CO) of
1967 cmÀ1, very close to those for complexes 4a and c,
indicating a similar net electron density at the ruthenium
centre.
3.2. General method for the synthesis of ligands 1c–e
But
But
O
O
PPh2
PPh2
But
But
O
O
PPh2
CO
[RuHCl(CO)(PPh3)3]
A mixture of the appropriate dry (toluene azeotrope)
resorcinol, chlorophosphine and NEt3 in toluene (20 ml)
was heated at reflux temperature for 18 h. The reaction
mixture was allowed to cool, filtered through celite and
the volatiles were removed under reduced pressure to give
the resorcinol bis(phosphinite) ligand.
Ru
toluene, Δ
Cl
PPh3
PPh2
1e
9
Scheme 4. Synthesis of complex 9.

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R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
3.2.1. 4,6-Di-tert-butylresorcinolbis(diphenylphosphinite)
(1c)
3.2.4. Reaction of 2-methyl-4,6,-di-tert-butylresorcinol with
chlorodiisopropylphosphine (3)
Chlorodiphenylphosphine (3.85 ml, 21.0 mmol), 4,6-di-
tert-butyl resorcinol (2.22 g, 10 mmol) and NEt3 (5.57 ml,
40 mmol) gave 1c as a white solid. Yield: 5.12 g (87%).
Anal. Calc. for C38H40O2P2: C, 77.3; H, 6.8. Found: C,
77.4; H, 6.8%. HRMS (CI) [M + H]+ Calc. for
C38H41O2P2: 591.2582. Found: 591.2602. 1H NMR
Chlorodiisopropylphosphine (3.98 ml, 25.0 mmol), 2
(2.36 g, 10 mmol) and NEt3 (6.40 ml, 40 mmol) were dis-
solved in toluene (20 ml) and heated at reflux for 18 h.
The resultant mixture was filtered through celite and the
volatiles were removed under reduced pressure to give a
white solid which contains a mixture of 2, 1f and 3. Ligand
3 could be obtained in a reasonably pure form (contains
ꢀ10% 2) by recrystallisation from Et2O (À20 ꢁC). Yield:
0.472 g (26%). Crystals of 3 suitable for X-ray analysis were
grown by recrystallisation from a concentrated Et2O solu-
tion at À20 ꢁC. Anal. Calc. for C21H37O2P: C, 71.6; H,
10.6. Found: C, 70.9; H, 10.1%. HRMS (CI) [M + H]+
Calc. for C21H37O2P: 353.2609. Found: 353.2638. 1H
t
(CDCl3, 300 MHz): d 1.59 (s, 18H, Bu), 7.51–7.72 (m,
14H, Ar-H), 8.07 (m, 8H, Ar-H). 31P NMR (CDCl3,
121.5 MHz): d 115.42 (s). 13C NMR (CDCl3, 75.5 MHz):
d 30.53 (s, C(CH3)3), 34.88 (s, C(CH3)3), 105.93 (s, Ar
CH), 106.90 (d, JCP = 23 Hz, Ar CH), 108.58 (t,
JCP = 22 Hz, Ar CH), 125.24 (s, Ar CH), 126.55 (s, Ar
C), 129.05 (s, Ar C), 129.23 (s, Ar C), 130.12 (s, Ar C),
130.81 (s, Ar C), 131.21 (s, Ar C), 132.48 (s, Ar C),
133.24 (s, Ar C), 140.93 (d, JCP = 18 Hz, Ar C), 154.01
(s, Ar C), 154.67 (d, JCP = 9 Hz, Ar CO).
3
NMR (CDCl3, 300 MHz): d 0.96 (d, 3H, JHH = 8 Hz,
3
CHCH3), 0.99 (d, 3H, JHH = 8 Hz, CHCH3), 1.00 (d,
3
3
3H, JHH = 8 Hz, CHCH3), 1.05 (d, 3H, JHH = 8 Hz,
CHCH3), 1.31 (s, 18H, C(CH3)3), 2.00–2.06 (m, 4H,
CH(CH3)2), 2.25 (s, 3H, Ar-CH3), 4.64 (br s, 1H, Ar-
OH), 6.98 (s, 1H, Ar-H). 31P NMR (CDCl3, 121.5 MHz):
d 160.95 (s). 13C NMR (CDCl3, 75.5 MHz): d 16.97 (s,
CHCH3), 17.01 (s, CHCH3), 28.96 (s, CHCH3), 29.16 (s,
CHCH3), 30.01 (s, C(CH3)3), 34.09 (s, C(CH3)3), 109.52
(s, Ar CH3), 120.85 (s, Ar CH), 125.77 (s, Ar C), 149.89
(s, Ar CO), 154.02 (d, JCP = 8 Hz, Ar CO).
3.2.2. 4,6-Di-tert-butylresorcinolbis(diisopropylphosphinite)
(1d)
Chlorodiisopropyl-phosphine (3.98 ml, 25.0 mmol), 4,6-
di-tert-butyl resorcinol (2.22 g, 10 mmol) and NEt3
(5.57 ml, 40 mmol) gave 1d as a crystalline white solid.
Yield: 4.41 g (91%). Anal. Calc. for C26H48O2P2: C, 68.7;
H, 10.6. Found: C, 68.0; H, 10.9%. HRMS (CI) [M + H]+
Calc. for C26H49O2P2: 455.3208. Found: 455.3196. 1H
3
NMR (CDCl3, 300 MHz): d 1.02 (d, 6 H, JHH = 8 Hz,
3.3. General method for the synthesis of
[Ru(PCP)Cl(CO)(PPh3)] complexes 4
3
CHCH3), 1.06 (d, 6H, JHH = 8 Hz, CHCH3), 1.08 (d,
3
3
6H, JHH = 8 Hz, CHCH3), 1.11 (d, 6H, JHH = 8 Hz,
CHCH3), 1.29 (s, 18H, C(CH3)3), 1.87–1.95 (m, 4H,
CH(CH3)2), 7.04 (s, 1H, Ar-H), 7.93 (t, 1H, JHP = 6 Hz,
Ar-H). 31P NMR (CDCl3, 121.5 MHz): d 139.48 (s). 13C
NMR (CDCl3, 75.5 MHz): d 18.02 (s, CHCH3), 18.08 (s,
CHCH3), 18.15 (s, CHCH3), 18.32 (s, CHCH3), 28.28 (s,
CHCH3), 28.53 (s, CHCH3), 30.75 (s, C(CH3)3), 34.92 (s,
C(CH3)3), 106.09 (t, JCP = 30 Hz, Ar CH), 125.57 (s, Ar
CH), 129.51 (s, Ar C), 155.79 (d, JCP = 9 Hz, Ar CO).
A mixture of [RuHCl(CO)(PPh3)3] and the appropri-
ate ligand 1 in toluene (15 ml) was heated at reflux for
18 h. The volatiles were removed under reduced pressure
and the crude product recrystallised from CH2Cl2:
hexane.
3.3.1. Complex 4a
Ligand 1a (0.268 g, 0.560 mmol) and [RuHCl(CO)
(PPh3)3] (0.533 g, 0.560 mmol) gave 4a as a light green
powder. Yield: 0.365 g (72%). Crystals suitable for X-ray
analysis were obtained from dichlorometahane/hexane.
Anal. Calc. for C49H38ClO3P3Ru: C, 65.1; H, 4.2. Found:
C, 65.9; H, 4.0%. 1H NMR (CDCl3, 300 MHz): d 6.28
3.2.3. 2-Methyl-4,6-di-tert-butylresorcinolbis
(diphenylphosphinite) (1e)
Chlorodiphenyl-phosphine (3.85 ml, 21.0 mmol),
2
(2.42 g, 10.2 mmol) and NEt3 (5.57 ml, 40 mmol) gave 1e
as a white solid, after washing with Et2O (2 · 10 ml). Yield:
4.87 g (79%). Anal. Calc. for C39H42O2P2: C, 77.5; H, 7.0.
Found: C, 77.2; H, 7.2%. HRMS (CI) [M + H]+ Calc.
for C39H43O2P2: 605.2738. Found: 605.2751. 1H NMR
4
3
(dd, 2H, JHP = 3 Hz and JHH = 9 Hz, Ar CH), 6.69 (t,
3
1H, JHH = 9 Hz, Ar CH), 6.87–7.51 (m, 35H, Ar CH).
31P NMR (CDCl3, 121.5 MHz): d 18.65 (t, 2JPP = 13.4 Hz,
PPh3), 147.16 (d, JPP = 13.4 Hz, phosphinite). 13C NMR
2
t
(CDCl3, 300 MHz): d 0.99 (s, 18H, Bu), 2.07 (br s, 3H,
(CDCl3, 75.5 MHz): d 103.04 (s, Ar CH), 106.56 (t,
JCP = 45 Hz, Ar C), 107.39 (s, Ar CH), 127.70 (s, Ar
CH), 127.45 (s, Ar CH), 12.90 (s, Ar CH), 127.99 (s, Ar
CH), 128.51 (s, Ar C), 130.54 (s, Ar CH), 130.64 (s,
Ar CH), 130.76 (s, Ar CH), 132.07 (s, Ar CH), 132.16 (s,
Ar C), 133.13 (s, Ar CH), 133.18 (s, Ar CH), 133.24
(s, Ar CH), 133.82 (s, Ar CH), 133.93 (s, Ar CH), 136.59
(s, Ar C), 157.43 (s, Ar C), 161.74 (t, JCP = 18 Hz, Ar C),
197.43 (dt, JCP = 8 and 16 Hz, Ru-CO). IR m(CO) (KBr
Ar-CH3), 7.02 (br s, 1H, Ar-H), 7.22–7.27 (m, 12H, PPh2
Ar-H), 7.52–7.57 (m, 8H, PPh2 Ar-H). 31P NMR (CDCl3,
121.5 MHz): d 114.26 (s). 13C NMR (CDCl3, 75.5 MHz):
d
8.91 (s, Ar-CH3), 30.62 (s, C(CH3)3), 34.98 (s,
C(CH3)3), 105.33 (s, Ar CH), 106.99 (d, JCP = 23 Hz, Ar
CH), 108.21 (t, JCP = 22 Hz, Ar CH), 125.64 (s, Ar CH),
126.49 (s, Ar C), 129.29 (s, Ar CH), 130.34 (s, Ar C),
131.86 (s, Ar C), 133.24 (s, Ar C), 140.78 (d, JCP = 18 Hz,
Ar C), 154.46 (d, JCP = 9 Hz, Ar C).
disc): 1966 cmÀ1
.

R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
1877
3
3.3.2. Complex 4b
H), 7.35 (t, 3H, JHH = 8 Hz, Ar-H), 7.67 (m, 4H, Ar-H).
31P NMR (CDCl3, 121.5 MHz): d 17.36 (t, 2JPP = 13.4 Hz,
Ligand 1b (0.222 g, 0.648 mmol) and [RuHCl(CO)
(PPh3)3] (0.618 g, 0.648 mmol) gave 4b as a dark green
powder. Yield: 0.336 g (67.5%). Anal. Calc. for
C37H46ClO3P3Ru: C, 57.9; H, 6.0. Found: C, 57.2; H,
6.2%. 1H NMR (CDCl3, 300 MHz): d 0.73 (q, 6H,
PPh3), 147.70 (d, JPP = 13.4 Hz, phosphinite). 13C NMR
2
(CD2Cl2, 75.5 MHz): d 30.33 (s, C(CH3)3), 34.53 (s,
C(CH3)3), 122.50 (s, Ar CH), 127.41 (s, Ar CH), 127.50
(s, Ar CH), 127.90 (s, Ar CH), 129.47 (s, Ar CH), 130.54
(s, Ar CH), 130.68 (s, Ar CH), 131.01 (d, J = 7 Hz, Ar
CH), 133.58 (s, Ar CH), 133.85 (d, J = 10 Hz, Ar CH),
136.28 (t, J = 6 Hz, Ar C), 156.89 (t, J = 6 Hz, Ar C),
198.07 (dt, J = 8 and 15 Hz, Ru-CO). IR m(CO) (KBr disc):
3JHH = 6 Hz, CHCH3), 0.83 (q, 6H, JHH = 6 Hz,
3
3
CHCH3), 0.94 (q, 6H, JHH = 6 Hz, CHCH3), 1.11 (q,
3
6H, JHH
=
6 Hz, CHCH3), 2.12 (br heptet, 2H,
3JHH = 6 Hz, CHCH3), 3.22 (br heptet, 2H, JHH = 6 Hz,
3
4
3
CHCH3), 6.50 (dd, 2H, JHP = 3 Hz and JHH = 9 Hz, Ar
1969 cmÀ1
.
3
CH), 6.80 (t, 1H, JHH = 9 Hz, Ar CH), 7.30 (m, 9H,
PPh3 Ar CH), 7.68 (m, 6H, PPh3 Ar CH). 31P NMR
3.3.4. Complex 4d
2
(CDCl3, 121.5 MHz): d 15.49 (t, JPP = 10.9 Hz, PPh3),
Ligand 1d (0.115 g, 0.253 mmol) and [RuHCl(CO)
(PPh3)3] (0.241 g, 0.253 mmol) gave 4d as a grey powder.
Yield: 0.172 g (78%). Anal. Calc. for C45H62ClO3P3Ru: C,
61.4; H, 7.1. Found: C, 60.8; H, 7.3%. H NMR (CDCl3,
300 MHz): d 0.81 (q, 6H, JHH = 6 Hz, CHCH3), 0.90 (q,
6H, JHH = 6 Hz, CHCH3), 0.98 (q, 6H, JHH = 6 Hz,
CHCH3), 1.17 (q, 6H, JHH = 6 Hz, CHCH3), 1.29 (s,
18H, C(CH3)3), 2.05 (br heptet, 2H, JHH = 6 Hz,
CHCH3), 3.08 (br heptet, 2H, JHH = 6 Hz, CHCH3),
182.69 (d, 2JPP = 10.9 Hz, phosphinite). 13C NMR (CDCl3,
75.5 MHz): d 17.81 (s, CHCH3), 17.98 (s, CHCH3), 18.53
(s, CHCH3), 18.90 (s, CHCH3), 28.86 (t, J = 10 Hz,
PCH), 31.35 (t, J = 11 Hz, PCH), 105.99 (s, Ar CH),
126.48 (s, Ar CH), 128.24 (d, J = 12 Hz, Ar CH), 128.78
(d, J = 12 Hz, Ar C) 129.91 (s, Ar CH), 132.16 (s, Ar
CH), 134.29 (d, J = 10 Hz, Ar CH), 138.36 (d, J = 31 Hz,
Ar C), 162.56 (t, J = 6 Hz, Ar C), 201.12 (dt, J = 8 and
1
3
3
3
3
3
3
15 Hz, Ru-CO). IR m(CO) (KBr disc): 1943, 1924 (sh) cmÀ1
.
6.82 (br s, 1H, Ar CH), 7.30 (m, 9H, PPh3 Ar CH), 7.68
(m, 6H, PPh3 Ar CH). 31P NMR (CDCl3, 121.5 MHz): d
2
2
3.3.3. Complex 4c
15.43 (t, JPP = 10.9 Hz, PPh3), 183.55 (d, JPP = 10.9 Hz,
phosphinite). 13C NMR (CDCl3, 75.5 MHz): d 18.81 (s,
CHCH3), 18.84 (s, CHCH3), 19.50 (s, CHCH3), 20.35 (s,
CHCH3), 29.59 (t, J = 11 Hz, PCH), 30.38 (s, C(CH3)3),
31.52 (t, J = 11 Hz, PCH), 34.51 (s, C(CH3)3), 123.11 (s,
Ar CH), 126.28 (dt, J = 2 and 48 Hz, Ar C), 127.85 (d,
J = 9 Hz, Ar CH), 128.41 (d, J = 12 Hz, Ar CH), 131.87
Ligand 1c (0.235 g, 0.398 mmol) and [RuHCl(CO)
(PPh3)3] (0.379 g, 0.398 mmol) gave 4c as a light green pow-
der. Yield: 0.286 g (71%). Anal. Calc. for C57H54ClO3P3Ru:
C, 67.4; H, 5.4. Found: C, 68.1; H, 5.9%. 1H NMR
(CDCl3, 300 MHz): d 1.29 (s, 18H, C(CH3)3), 6.85 (m,
6H, Ar-H), 6.97 (br s, 1H, Ar-H), 7.01–7.29 (m, 22H, Ar-
Table 3
Crystal data and refinement parameters for compounds 2, 3 and 4a
Compound
2
3
4a
C49H38ClO3P3Ru
904.22
monoclinic
P21/n
Empirical formula
Formula weight
Crystal system
Space group
C
236.34
monoclinic
C2/c
15H24O2
C25H47O3P
426.60
monoclinic
P21/c
Unit cell dimensions
˚
a (A)
21.874(4)
8.077(6)
16.087(3)
90
90.36(3)
90
2842.1(10)
8
1.105
10.9605(7)
15.7678(8)
15.333(7)
90
102.024(5)
90
2591.8(2)
4
1.093
10.0759(12)
20.2499(18)
20.470(14)
90
92.71(3)
90
4172(3)
4
1.440
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
Volume (A )
Z
Density (calc) (Mg/m3)
Absorption coefficient (mmÀ1
F(000)
)
0.071
1040
0.127
944
0.598
1848
Crystal size (mm)
hmax (ꢁ)
0.6 · 0.16 · 0.04
27.49
0.5 · 0.2 · 0.1
27.50
0.2 · 0.1 · 0.1
25.02
Reflections collected
15 430
26 838
7073
Independent reflections (I > 2rI)
Rint
1674
0.0923
4864
0.0327
5992
0.0421
Final R indices
F2 > 2rF2
Dq max/min (e A
R1 = 0.0617
wR2 = 0.1480
0.283/À0.295
R1 = 0.0365
wR2 = 0.0892
0.311/À0.326
R1 = 0.0297
wR2 = 0.0828
0.341/À0.372
À3
˚
)

1878
R.B. Bedford et al. / Inorganica Chimica Acta 359 (2006) 1870–1878
(s, Ar CH), 134.16 (d, J = 11 Hz, Ar CH), 138.36 (d,
J = 23 Hz, Ar C), 157.82 (t, J = 5 Hz, Ar C), 201.15 (dt,
J = 9 and 14 Hz, Ru-CO). IR m(CO) (KBr disc): 1945,
Acknowledgements
We thank Enterprise Ireland (studentship for PNS) and
the EPSRC (Advanced Research Fellowship for RBB,
PDRAs for MB and MEB) for funding.
1923 (sh) cmÀ1
.
3.4. Complex 9
References
Ligand 1e (0.13 g, 0.215 mmol) and [RuHCl(CO)
(PPh3)3] (0.205 g, 0.215 mmol) were dissolved in toluene
(10 ml) and heated at reflux for 18 h. The volatiles were
removed under reduced pressure to give a crude orange
solid. The crude product was recrystallised from
CH2Cl2:hexane and dried in vacuo to give complex 9
as a light green powder. Yield: 0.20 g (61.5%). Anal.
Calc. for C58H56ClO3P3Ru: C, 67.6; H, 5.5. Found: C,
69.7; H, 5.8%. 1H NMR (CDCl3, 300 MHz): d 1.26 (s,
18H, C(CH3)3), 3.08 (br d, 2H, Ar-CH2-Ru), 6.86 (br t,
[1] For reviews see: (a) J. Dupont, C.S. Consorti, J. Spencer, Chem. Rev.
105 (2005) 2527;
(b) I.P. Beletskaya, A.V. Cheprakov, J. Organometal. Chem. 689
(2004) 4055;
(c) R.B. Bedford, Chem. Commun. (2003) 1787;
(d) M. Albrecht, G. van Koten, Angew. Chem. Int. Ed. 40 (2001)
3750;
(e) J. Dupont, M. Pfeffer, J. Spencer, Eur. J. Inorg. Chem. (2001) 1917;
(f) I.P. Beletskaya, A.V. Cheprakov, Chem. Rev. 100 (2000) 3006.
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Soc. 119 (1997) 11687;
3
(b) S. Sjo¨vall, O.P. Wendt, C. Andersson, J. Chem. Soc., Dalton
Trans. (2002) 1396;
(c) D. Morales-Morales, R.E. Cramer, C.M. Jensen, J. Organomet.
Chem. 654 (2002) 44;
(d) R.B. Bedford, S.M. Draper, P.N. Scully, S.L. Welch, New J.
Chem. 24 (2000) 745;
4H, JHH = 6 Hz, Ar-H), 6.98 (br s, 1H, Ar-H), 7.03–
7.27 (m, 20H, Ar-H), 7.29–7.41 (m, 3H, Ar-H), 7.55–
7.79 (m, 8H, Ar-H). 31P NMR (CDCl3, 121.5 MHz): d
2
2
17.30 (t, JPP = 13.4 Hz, PPh3), 147.69 (d, JPP
=
13.4 Hz, phosphinite). 13C NMR (CDCl3, 75.5 MHz): d
30.54 (s, C(CH3)3), 34.62 (s, C(CH3)3), 66.93 (d,
2JCP = 211 Hz, CH2-Ru), 122.50 (s, Ar CH), 127.34 (s,
Ar CH), 127.87 (s, Ar CH), 127.96 (s, Ar CH), 130.35
(s, Ar CH), 130.38 (s, Ar CH), 130.48 (s, Ar CH),
131.27 (d, J = 7 Hz, Ar CH), 133.50 (s, Ar CH), 133.72
(d, J = 5 Hz, Ar CH), 133.98 (s, Ar CH), 134.91 (s, Ar
CH), 136.20 (t, J = 7 Hz, Ar C), 157.07 (t, J = 6 Hz,
Ar C), 199.13 (dt, J = 8 and 15 Hz, Ru-CO). IR m(CO)
´
(e) D. Morales-Morales, R. Redon, C. Yung, C.M. Jensen, Chem.
Commun. (2000) 1619;
(f) F. Miyazaki, K. Yamaguchi, M. Shibasaki, Tetrahedron Lett. 40
(1999) 7379.
[3] (a) N. Solin, J. Kjellgren, K.J. Szabo´, J. Am. Chem. Soc. 126 (2004)
7026;
´
(b) N. Solin, O.A. Wallner, K.J. Szabo, Org. Lett. 7 (2005) 689;
´
(c) O.A. Wallner, K.J. Szabo, Org. Lett. 6 (2004) 1829.
[4] (a) F. Gorla, A. Togni, L.M. Venanzi, A. Albinati, F. Lianza,
Organometallics 13 (1994) 1607;
(KBr disc): 1967 cmÀ1
.
(b) J.M. Longmire, X. Zhang, M. Shang, Organometallics 17 (1998)
4374.
[5] P. Dani, T. Karlen, R.A. Gossage, S. Gladiali, G. van Koten,
Angew. Chem. Int. Ed. 39 (2000) 743.
4. X-ray crystallography
[6] M. Albrecht, B.M. Kocks, A.L. Spek, G. van Koten, J. Organomet.
Chem. 624 (2001) 271.
[7] For a review see: C.M. Jensen, Chem. Commun. (1999) 2443.
[8] I. Go¨ttker-Schnetmann, P. White, M. Brookhart, J. Am. Chem. Soc.
126 (2004) 1804.
The data collection and refinement parameters of
structures 2, 3 and 4a are presented in Table 3. All data
for 4a were collected on a Enraf-Nonius CAD-4 area
detector diffractometer at 293 K with Mo Ka radiation
(k = 0.71073 A). For 2 and 3 X-ray diffraction data were
collected by means of combined phi and omega scans on
a Bruker-Nonius KappaCCD area detector situated at
´
[9] D. Morales-Morales, C. Grause, K. Kasaoka, R. Redon, R.E.
˚
Cramer, C.M. Jensen, Inorg. Chim. Acta 300–302 (2000) 958.
[10] R.B. Bedford, M.E. Blake, S.J. Coles, M.B. Hursthouse, P.N. Scully,
Dalton Trans. (2003) 2805.
[11] R.B. Bedford, S.L. Hazelwood, M.E. Limmert, D.A. Albisson, S.M.
Draper, P.N. Scully, S.J. Coles, M.B. Hursthouse, Chem. Eur. J. 9
(2003) 3216.
[12] C.G. Leong, O.M. Akotsi, M.J. Ferguson, S.H. Bergens, Chem.
Commun. (2003) 750.
[13] P. Dani, B. Richter, G.P.M. van Klink, G. van Koten, Eur. J. Inorg.
Chem. (2001) 125.
[14] M.E. van de Boom, H.-B. Kraatz, L. Hassner, Y. Ben-David, D.
Milstein, Organometallics 18 (1999) 3873.
[15] P.J. Halfpenny, P.J. Johnson, M.J.T. Robinson, M.G. Ward,
Tetrahedron 32 (1976) 1873.
[16] G.M. Sheldrick, SHELX97: Programs for Structure Solution and
Refinement, University of Go¨ttingen, Germany, 1997.
[17] G.M. Sheldrick, SADABS Version 2.10, Bruker AXS Inc, Madison, WI,
USA, 2003.
the window of
a
rotating anode (k(Mo Ka) =
˚
0.71073 A). All the structures were solved by direct meth-
ods, SHELXS-97 and refined using SHELXL-97 [16]. Hydro-
gen atoms were included in the refinement, but thermal
parameters and geometry were constrained to ride on
the atom to which they are bonded. The data for 2
and 3 were corrected for absorption effects using SADABS
[17]. The complete crystallographic data have also been
deposited with the Cambridge Crystallographic Data
Centre
[deposition
numbers
are
CCDC274508,
CCDC274507 and CCDC275894 for compounds 2, 3
and 4a, respectively].