Ruthenium(III) complexes containing bi-and tridentate phosphorus-nitrogen ligands

Article abstract of DOI:10.1139/cjc-2013-0539

Air-stable Ru^III complexes containing a bidentate aminophosphine ligand (PN) of the type mer-RuCl₃(PN)(PR₃) are made from the precursors RuCl₃(PR₃)₂(DMA)·DMA (PN = o-diphenylphosphino-N,N′-dimethylaniline (P-N) and (R)-N,N′- dimethyl-1-[o-diphenylphosphinophenyl]ethylamine ((R)-AMPHOS); R = Ph, p-tolyl; DMA = N,N′-dimethylacetamide). With the tridentate bis[o-(N,N′- dimethylamino)phenyl]phenylphosphine (BNP), the product is mer-RuCl ₃(BNP) (3), while tris[o-(N,N′-dimethylaminophenyl)phosphine (TNP) is unreactive toward the precursor. Crystal structures of mer-RuCl ₃(PN)(PPh₃), where PN is P-N (2a), (R)-AMPHOS (4a), and 3·CHCl₃ are reported as well as those of (R)-AMPHOS, BNP, and TNP. The Ru^III-aminophosphine complexes are the first monomeric Ru^III species to be formed via the useful, easily synthesized, air-stable Ru^III precursors RuCl₃(PR₃) ₂(DMA)·DMA (1a and 1b); complex 2a is formed also via reaction of HCl with trans-RuCl₂(P-N)(PPh₃). A crystal structure of mer,cis-RuCl₃(DMA)₂(PPh₃)·DMA (1c), a side-product from the synthesis of the Ru^III precursor, is also presented and is the first-reported complex of DMA with Ru^III. Preliminary data show that the Ru^III-aminophosphine complexes in DMA (a proton-accepting solvent) are reduced by H₂ to Ru^II species that can react further to form an η²-H₂ adduct and then a Ru^II-hydridochloro species.

Full text of DOI:10.1139/cjc-2013-0539

716
ARTICLE
Ruthenium(III) complexes containing bi- and tridentate
phosphorus−nitrogen ligands
Dona C. Mudalige, Erin S.F. Ma, Steven J. Rettig, Brian O. Patrick, and Brian R. James
Abstract: Air-stable RuIII complexes containing a bidentate aminophosphine ligand (PN) of the type mer-RuCl3(PN)(PR3) are made
from the precursors RuCl3(PR3)2(DMA)·DMA (PN = o-diphenylphosphino-N,N=-dimethylaniline (P−N) and (R)-N,N=-dimethyl-1-[o-
diphenylphosphinophenyl]ethylamine ((R)-AMPHOS); R = Ph, p-tolyl; DMA = N,N=-dimethylacetamide). With the tridentate bis[o-(N,N=-
dimethylamino)phenyl]phenylphosphine (BNP), the product is mer-RuCl3(BNP) (3), while tris[o-(N,N=-dimethylaminophenyl)phosphine (TNP)
is unreactive toward the precursor. Crystal structures of mer-RuCl3(PN)(PPh3), where PN is P−N (2a), (R)-AMPHOS (4a), and 3·CHCl3 are
reported as well as those of (R)-AMPHOS, BNP, and TNP. The RuIII−aminophosphine complexes are the first monomeric RuIII species to
be formed via the useful, easily synthesized, air-stable RuIII precursors RuCl3(PR3)2(DMA)·DMA (1a and 1b); complex 2a is formed also
via reaction of HCl with trans-RuCl2(P−N)(PPh3). A crystal structure of mer,cis-RuCl3(DMA)2(PPh3)·DMA (1c), a side-product from the
synthesis of the RuIII precursor, is also presented and is the first-reported complex of DMA with RuIII. Preliminary data show that the
RuIII−aminophosphine complexes in DMA (a proton-accepting solvent) are reduced by H2 to RuII species that can react further to form
an ␩2-H2 adduct and then a RuII-hydridochloro species.
Key words: Ru(III) complexes, phosphorus−nitrogen ligands, N,N=-dimethylacetamide complex, HCl as oxidant, crystallography.
Résumé : Les complexes de l’ion RuIII du type mer-RuCl3(PN)(PR3), comportant un ligand bidentate aminophosphine (PN), sont
synthétisés a` partir des précurseurs RuCl3(PR3)2(DMA)·DMA (PN = o-diphénylphosphino-N,N=-diméthylaniline (ligand P−N) et
(R)-N,N=-diméthyl-1-[o-diphénylphosphinophényl]éthylamine ((R)-AMPHOS); R = Ph, p-tolyl; DMA = N,N=-diméthylacétamide). Avec
le tridentate bis[o-(N,N=-diméthylamino)phényl]phénylphosphine (BNP), le produit obtenu est un mer-RuCl3(BNP) (3), alors que
tris[o-(N,N=-diméthylamino)phényl]phosphine (TNP) ne montre aucune réactivité avec le précurseur. Les structures cristallines
des ligands mer-RuCl3(PN)(PPh3), où PN représente le ligand P−N (2a) et (R)-AMPHOS (4a), et 3·CHCl3 ainsi que celles des ligands
(R)-AMPHOS, BNP et TNP sont décrites dans le présent article. Les complexes RuIII−aminophosphine sont les premières espèces
monomériques a` être produites a` l’aide des précurseurs du RuIII, utiles, facilement synthétisables et stable a` l’air, de formule
RuCl3(PR3)2(DMA)·DMA (1a et 1b). Le complexe 2a est produit par la réaction du HCl avec trans-RuCl2(P−N)(PPh3). La structure
cristalline du complexe mer,cis-RuCl3(DMA)2(PPh3)·DMA (1c), sous-produit de la synthèse du précruseur du RuIII, est également
présent dans le présent article. Il s’agit du premier complexe jamais observé formé a` partir du DMA et du RuIII. Des données
préliminaires montrent que que les complexes de RuIII−aminophosphine dans le DMA (solvant accepteur de protons) sont
réduits pas H2 pour former des complexes du RuII pouvant réagir a` leur tour et produire un adduit de formule ␩2-H2 puis des
complexes RuII-hydridochloro. [Traduit par la Rédaction]
Mots-clés : complexes du Ru(III), ligands phosphore−azote, complexe N,N=-diméthylacétamide, HCl comme oxydant, cristallographie.
of RuII.4c,4d The syntheses of these complexes from reaction of
RuCl3·3H2O with a twofold excess of PR3 in DMA at room temper-
Introduction
Ruthenium phosphine chemistry has been an ongoing interest
ature have been briefly described,4c and further details on these
in our group for almost 50 years,1 a shorter time than one of us
syntheses, and one of a RuCl3(DMA)2(PPh3)·DMA (1c) side-product,
(B.R.J.) has known Barry Lever! Of note, the first report on asym-
are presented in this current paper. More importantly, we report
here on the reactions of 1a and 1b with four known aminophos-
phines, one of which is chiral (Scheme 1), to form air-stable RuIII
complexes; some data are also presented on the reactivity of the
RuIII products toward H2. The first three aminophosphines were
first reported by Venanzi’s group5 and the chiral one by Tsuji’s
group6 with Payne and Stephan later providing synthesis and char-
acterization details;7 crystal structures of BNP, TNP, and (R)-AMPHOS
(referred to hereafter as AMPHOS) are also reported here in our
paper.
metric hydrogenation of olefinic substrates using RuII-chiral phos-
phine species appeared from our group in 1975,2 and a readily
observed problem with using such precursor catalyst species is
their sensitivity to O2 (with concomitant formation of phosphine
oxides3); thus, air-stable RuIII−phosphine complexes were synthe-
sized4 because these could be readily reduced in situ by H2 to RuII,
the required oxidation state for catalytic hydrogenation.4a–4d We
have used previously the air-stable complexes RuIIICl3(PR3)2(DMA)·DMA,
R = Ph (1a) or p-tolyl (1b), which contain both a coordinated and
solvate N,N=-dimethylacetamide molecule as a convenient source
Received 20 November 2013. Accepted 17 January 2014.
D.C. Mudalige, E.S.F. Ma, S.J. Rettig,* B.O. Patrick, and B.R. James. Department of Chemistry, The University of British Columbia, Vancouver,
BC V6T 1Z1, Canada.
Corresponding author: Brian R. James (e-mail: brj@chem.ubc.ca).
*Deceased October 27, 1998.
This article, based on Ru(III) chemistry, is dedicated to Professor A.B.P. (Barry) Lever in recognition of his contributions (particularly in ruthenium chemistry) to the development
of Canadian chemistry.
Can. J. Chem. 92: 716–723 (2014) dx.doi.org/10.1139/cjc-2013-0539
Published at www.nrcresearchpress.com/cjc on 29 January 2014.

Mudalige et al.
717
Scheme 1. The aminophosphines used in the studies.
NMe2
PPh2
H
NMe2
NMe2
NMe2
PPh2
Me2N
Me
P
P
Me2N
BNP
Me2N
TNP
P
N
(R)-AMPHOS
N,N'-dimethyl-1-[o-diphenyl-
phosphinophenyl]ethylamine
o-diphenylphosphino-
N,N'-dimethylaniline
bis[o-(N,N'-dimethylamino)-
tris[o-(N,N'dimethylamino-
phenyl]phenylphosphine
phenyl)]phosphine
RuCl3(P(p-tolyl3))2(DMA)·DMA (1b)
Experimental section
The synthesis was the same as described for 1a but using a
twofold excess of P(p-tolyl)3 (4.7 g, 15.3 mmol). Yield: 4.0 g, 53%.
Anal. calcd. C50H60N2O2Cl3P2Ru: C 60.64, H 6.06, N 2.83, Cl 10.76;
found: C 60.5, H 6.1, N 2.9, Cl 10.6. IR (Nujol): ␯C=O 1646 (free DMA)
and 1598 (coordinated DMA).
General procedures
All manipulations were carried out under an O2-free argon
atmosphere at room temperature (r.t.) (ϳ22 °C) using standard
Schlenk techniques. Analytical-grade solvents and CDCl3 from
Cambridge Isotope Laboratories were purified and stored using
standard methods;8 DMA was stirred over CaH2 for at least 24 h,
vacuum distilled at 35–40 °C, and stored under argon in the dark.
Purified argon (H.P.) and H2 (Research, extra dry) were Union Car-
bide Canada products, and anhydrous HCl was obtained from the
Matheson Gas Co.; the argon was dried by passage through CaSO4
columns, and H2 was passed through an Engelhard Deoxo cata-
lytic hydrogen purifier to remove trace O2. The aminophosphines
P−N,5 bis[o-(N,N=-dimethylamino)phenyl]phenylphosphine (BNP),5
TNP,5 and AMPHOS7 were synthesized by the reported methods;
X-ray-quality crystals of BNP and TNP were obtained by recrystal-
lization from their ethanol solutions, and crystals of AMPHOS
were acquired by slow evaporation of a benzene solution of the
compound. The RuCl3·3H2O was donated by Colonial Metals Inc.,
and trans-RuCl2(P–N)(PPh3) was made as reported.9 Proton sponge
(PS = 1,8-bis(dimethylamino)naphthalene) was obtained from
Aldrich. NMR spectra were recorded at r.t. on Varian XL300
(300.0 MHz for 1H and 121.4 MHz for 31P) or Bruker AMX500
mer-RuCl3(P−N)(PPh3) (2a)
(a) A suspension of 1a (1.0 g, 1.10 mmol) and P−N (0.34 g,
1.10 mmol) in 100 mL of hexanes was refluxed for 24 h and
then cooled to r.t., when a red solid precipitated. This was
collected and washed with hexanes (4 × 15 mL), dissolved in
CH2Cl2, and reprecipitated by addition of hexanes. Yield:
0.77 g, 90%. Anal. calcd. C38H35NCl3P2Ru: C 58.89, H 4.55,
N 1.81; found: C 58.7, H 4.7, N 1.8; ␮eff = 2.0 BM. X-ray-quality
crystals of 2a were obtained by layering hexanes onto a
CH2Cl2 solution of the complex.
(b) In an NMR-scale reaction, 1 atm of anhydrous HCl was bub-
bled at r.t. through a dark green C6D6 solution of trans-
RuCl2(P-N)(PPh3) (ϳ10−2 mol L−1). The colour immediately
became deep red, and the 31P{1H} AX doublets of the RuII
reactant (␦ 83.69 and 48,87, 2JPP = 36.5 Hz)9 disappeared; some
red crystals deposited on slow evaporation of the solvent, and
an X-ray structure revealed the compound to be 2a. Anal.
found: C 58.7, H 4.6, N 1.8.
1
(500.0 MHz for H and 202.5 MHz for 31P) instruments. Residual
deuterated solvent protons (relative to external SiMe4) and exter-
nal 85% H3PO4 were used as references. Infrared data were re-
corded on a Bomem Michelson 100 FTIR instrument and are
reported in cm−1. The magnetic susceptibilities of the RuIII−PN
complexes were determined at 20 °C by either the Evans’ method
(for the P(p-tolyl)3-containing species) using CDCl3 solutions con-
taining ϳ2% t-butanol and the complex10 or the Gouy method (for
the less soluble PPh3-containing species) using a Johnson−Matthey
Magnetic Susceptibility Balance, diamagnetic contributions from
RuIII and ligands being calculated from Pascal’s constants.11 Micro-
analyses were performed in this department on a Carlo Erba 1106
instrument; chloride was measured gravimetrically using AgNO3.
mer-RuCl3(P−N)(P(p-tolyl3)) (2b)
The complex was prepared as described for 2a but using 1b as
precursor (1.0 g, 1.01 mmol). Yield: 0.73 g, 88%. Anal. calcd.
C41H41NCl3P2Ru: C 60.26, H 5.06, N 1.71, Cl 13.02; found: C 60.4,
H 5.2, N 1.6, Cl 13.3. ␮eff = 1.73 BM.
mer-RuCl3(BNP) (3)
A solution of BNP (38.0 mg, 0.11 mmol) in CH2Cl2 (10 mL) was
added to a solution of 1a (100.0 mg, 0.11 mmol) in CH2Cl2 (10 mL),
and the mixture was stirred for 2.5 h during which time an orange
solution formed. The solution volume was then reduced to 3 mL,
and hexanes (10 mL) were added to precipitate a dark orange solid
that was collected and washed with hexanes (2 × 10 mL). Yield:
55 mg, 90%. Satisfactory elemental analysis was not obtained even
RuCl3(PPh3)2(DMA)·DMA (1a) and
mer,cis-RuCl3(DMA)2(PPh3)·DMA (1c)
Solid PPh3 (4.0 g, 15.3 mmol) was added to a dark brown solution
of RuCl3·3H2O (2.0 g, 7.6 mmol) in DMA (60 mL) and the mixture
was stirred at r.t. for 24 h. The air-stable, green precipitate was
filtered off, washed with DMA (2 × 5 mL) and hexanes (3 × 5 mL),
and dried under vacuum. Yield of 1a: 5.2 g, 75%. Anal. calcd.
C44H48N2O2Cl3P2Ru: C 58.32, H 5.34, N 3.09, Cl 11.76; found: C 58.2,
after three reprecipitations with CH2Cl2−hexanes. ␮ = 1.5 BM.
eff
Orange crystals of 3·CHCl3 were obtained by slow evaporation
from a CHCl3 solution of the complex.
mer-RuCl3(AMPHOS)(PPh3) (4a)
H 5.2, N 3.0, Cl 11.8. IR (Nujol): ␯
1632 (free DMA) and 1590
C=O
The complex was prepared as described for 2a but using
AMPHOS as the aminophosphine (0.37 g, 1.10 mmol); the product
was bright red. Yield: 0.71 g, 80%. Anal. calcd. C40H39NCl3P2Ru:
(coordinated DMA), ␯
335 and 319. ␮ = 1.84 BM. After
Ru−Cl
eff
ϳ4 weeks, dark red crystals precipitated from the DMA filtrate,
their identity being established first by X-ray analysis. Yield of 1c:
ϳ0.5 g, 9%. Anal. calcd. C30H42N3O3Cl3PRu: C 49.29, H 5.79, N 5.75;
C 59.82, H 4.89, N 1.74; found: C 59.7, H 5.0, N, 1.7. ␮ = 1.5 BM.
eff
X-ray-quality crystals of 4a were obtained by layering hexanes
found: C 49.1, H 5.9, N 5.8. IR (Nujol): ␯
1635 (free DMA), 1593
C=O
and 1572 (coordinated DMA).
onto a CH2Cl2 solution of the complex.
Published by NRC Research Press

718
Can. J. Chem. Vol. 92, 2014
Table 1. Crystallographic data for the aminophosphine ligands.
Crystal
BNP
TNP
(R)-AMPHOS
Formula
C
22H25N2P
C24H30N3P
391.48
Colourless, irregular
0.40×0.40×0.30
Triclinic
P1 (#2)
C23H24NP
333.41
Colourless, prism
0.25×0.35×0.40
Triclinic
P1(#1)
10.484(2)
12.486(2)
8.582(1)
96.09(2)
103.74(1)
114.79(1)
963.3(3)
2
Formula weight
Crystal colour, habit
Crystal size (mm)
Crystal system
Space group
348.41
Colourless, plate
0.04×0.25×0.30
Monoclinic
Cc(#9)
9.026(1)
14.859(2)
15.677(1)
90
106.119(7)
90
2019.9(4)
4
´
a (Å)
7.582(1)
9.098(1)
´
b (Å)
´
c (Å)
16.969(4)
83.859(7)
87.340(3)
65.63(1)
1060.1(3)
2
␣ (°)
␤ (°)
␥ (°)
´
V (Å3)
Z
Dc (g cm−3
)
1.146
12.3
1.226
1.44
1.149
1.40
␮ (cm−1
)
Total no. of reflections
No. of unique reflections
2271
9643
4789 (Rint = 0.044)
4663
4418 (Rint = 0.017)
2168 (Rint = 0.024)
No. of variables
R1
wR2
231
259
431
0.069 (I > 2␴(I))
0.240 (I > 2␴(I))
1.12
0.23
−0.32
0.041 (I > 2␴(I))
0.103 (I > 2␴(I))
0.96
0.23
−0.46
0.033 (I > 3␴(I))
0.032 (I > 3␴(I))
1.85
0.12
−0.16
Goodness-of-fit
´
Max. diff. (e Å−3
´
)
Min. diff. (e Å−3
)
Table 2. Crystallographic data for the RuIII complexes.
Crystal
2a
3·CHCl3
4a
1c
Formula
C38H35NCl3P2Ru C23H26N2Cl6PRu C40H39NCl3P2Ru C30H42N3O3Cl3PRu
Formula weight
Crystal colour, habit
Crystal size (mm)
Crystal system
Space group
775.08
675.25
803.13
Red, prism
731.08
Red, prism
0.30×0.40×0.45
Orthorhombic
Pna21(#33)
Orange, plate
0.03×0.25×0.25
Monoclinic
P21/n(#14)
Red, unavailablea
0.12×0.25×0.25 Unavailablea
Orthorhombic Orthorhombic
P212121(#19)
P212121(#19)
´
a (Å)
19.615(3)
17.538(2)
13.027(3)
10.470(2)
13.311(3)
20.649(3)
9.839(3)
10.252(2)
´
b (Å)
´
c (Å)
10.152(1)
90, 90, 90
21.221(3)
90, 106.92, 90
13.187(4)
90, 90, 90
33.568(7)
90, 90, 90
␣, ␤, ␥ (°)
´
V (Å3)
3492.4(7)
4
1.474
7.9
2769.1(9)
4
1.620
105.8
6028
3624(1)
4
1.472
7.63
3601
3386(5)
4
1.43
Z
Dc (g cm−3
)
␮ (mm−1
Total no. of reflections
)
7.72
8466
Unavailablea
No. of unique reflections 8040 (Rint = 0.057) 5414 (Rint = 0.033) 2356 (I > 3␴(I)) 3861 (I > 3␴(I))
No. of variables
R1
wR2
409
302
424
388
0.030 (I > 2␴(I))
0.078 (I > 2␴(I))
0.97
0.52
−1.08
0.056 (I > 2␴(I))
0.153 (I > 2␴(I))
1.05
1.13
−1.20
0.030 (I > 3␴(I)) 0.034 (I > 3␴(I))
0.030
1.25
0.26
−0.32
0.043
1.54
0.78
Unavailablea
Goodness-of-fit
´
Max. diff. (e Å−3
)
´
Min. diff. (e Å−3
)
aSee Appendix C (supplementary material).
mer-RuCl3(AMPHOS)(P(p-tolyl3)) (4b)
aminophosphines and complexes, respectively. Full details for
data collection, data reduction, structure solution and refine-
ment, and the relevant references for the procedures used are
given in the “Supplementary material” section, which contains
crystallographic data in CIF format for BNP, TNP, 2a, and 3·CHCl3
(CCDC Nos. 962715–962718, respectively) and Appendices A, B, and
C for the structures of AMPHOS, 4a, and 1c, respectively, in non-
CIF format.
The complex was prepared as described for 2a but using 1b as
precursor (1.0 g, 1.01 mmol) and an equimolar amount of AMPHOS
(0.34 g, 1.01 mmol). A yield of 0.66 g (77%) of the bright red product
was obtained. Anal. calcd. C43H45NCl3P2Ru: C 61.11, H 5.37, N 1.66,
Cl 12.58; found: C 61.4, H 5.6, N 1.7, Cl 12.4. ␮eff = 1.87 BM.
X-ray crystallographic analyses
The structural measurements for the aminophosphines and the
four RuIII complexes were carried out on Rigaku instruments
(AFC6S or ADSC area detector). Graphite monochromated MoK␣
radiation (0.71069 Å) was used for TNP, AMPHOS, 2a, and 4a; CuK␣
radiation (1.54178 Å) was used for BNP and 3·CHCl3. Data were
collected at 21 1 °C, except for the TNP structure when –93 1 °C
was used. Tables 1 and 2 list some crystallographic data for the
Results and discussion
Structures of the aminophosphines
Although the four aminophosphines shown in Scheme 1 have
been known for at least 30 years, only the crystal structure of P−N
has been reported;12 this paper also gives a survey of the early
Published by NRC Research Press

Mudalige et al.
719
Table 3. Selected bond lengths and angles for BNP, TNP, and (R)-
Fig. 2. ORTEP diagram of TNP with 33% probability thermal ellipsoids.
AMPHOS, with estimated standard deviations in parentheses.
Bond
Length (Å)
Bond
Angle (°)
BNP
C(1)−P(1)
C(7)−P(1)
C(13)−P(1)
C(1)−P(1)
C(9)−P(1)
C(17)−P(1)
C(1)−P(1)
C(7)−P(1)
C(13)−P(1)
1.836 (7)
1.841 (8)
1.847 (8)
1.8470 (15)
1.8534 (16)
1.8526 (14)
1.840 (6)
1.837 (5)
C(1)−P(1)−C(7)
C(1)−P(1)−C(13)
C(7)−P(1)−C(13)
C(1)−P(1)−C(9)
C(1)−P(1)−C(17)
C(9)−P(1)−C(17)
C(1)−P(1)−C(7)
C(1)−P(1)−C(13)
C(7)−P(1)−C(13)
103.6 (3)
98.3 (3)
102.1 (4)
101.30 (7)
99.46 (6)
101.01 (7)
100.9 (2)
102.8 (3)
101.6 (2)
TNP
(R)-AMPHOSa
1.835 (5)
aData for one of two independent molecules in the asymmetric unit.
Fig. 1. ORTEP diagram of BNP with 33% probability thermal ellipsoids.
Fig. 3. ORTEP diagram of (R)-AMPHOS with 50% probability thermal
ellipsoids; one of two independent molecules in the asymmetric unit.
work on metal−PN ligand systems in homogeneous catalysis.
Thus, crystals of BNP, TNP, and AMPHOS were subjected to X-ray
analysis. Table 3 lists selected bond lengths and angles for these
three aminophosphines.
BNP contains one more dimethylamino group than P–N and has
three potential binding sites. As expected, the ORTEP diagram
(Fig. 1) reveals trigonal pyramidal geometry about the phosphorus
atom; the average P–C bond length of 1.84 Å is basically the same
as that of PPh3 (1.83 Å), while the C(1)–P(1)–C(7) (103.6°), C(7)–P(1)–
C(13) (102.1°), and C(1)–P(1)–C(13) (98.3°) bond angles differ slightly
from the average C–P–C angle of 103° in PPh3,13 the difference
presumably arising because of the steric effects of the NMe2
groups. The dihedral angles for the P(1)−C(1)–C(2)–N(1) and P(1)–
C(7)–C(8)–N(2) planes are –1.2(7)° and 3.7(8)°, respectively, indicat-
ing that the NMe2 groups and the phosphorus atom lone pair
point essentially in the same direction.
TNP with three NMe2 groups has four potential binding sites
and, like BNP, the structure (Fig. 2) shows that the phosphorus
atom and the amino groups point in the same direction as indi-
cated by the small dihedral angles of –2.4(2)°, –10.9(2)°, and 4.4(2)°
for the three relevant P–C–C–N planes. The P–C bond lengths and
C–P–C angles are in the ranges 1.84−1.85 Å and 99.4°−101.3°, re-
spectively.
In all three aminophosphines, the N–C bond lengths and C–N–C
angles are in the ranges of 1.41–1.48 Å and 108–116°, respectively,
and are again standard values.
Ruthenium(III)−aminophosphine complexes
On the 1:1 reactions of the RuIII precursors 1a and 1b with each
of P−N, BNP, and AMPHOS, PR3 and DMA ligands are substituted,
and air-stable RuIII−PN complexes are generated: P−N forms the
mer-RuCl3(P-N)(PR3) complexes 2a (R = Ph) and 2b (R = p-tolyl),
BNP forms mer-RuCl3(BNP) (3), and (R)-AMPHOS gives the mer-RuCl3-
(AMPHOS)(PR3) species 4a (R = Ph) and 4b (R = p-tolyl). The chem-
istry is summarized in Scheme 2.
The AMPHOS structure, which confirms the (R)-configuration, is
shown in Fig. 3; there are two independent molecules in the asym-
metric unit (one is shown), and these are related by a pseudo-
centre of symmetry with only the chiral amine portion of the
structure breaking the pseudo-inversion symmetry. The P–C bond
lengths and C–P–C angles of both molecules are “standard”, being,
respectively, 1.83−1.84 Å and 101.6°−102.8°.
TNP did not react with 1a or 1b, under the conditions used for
the three other PN ligands, presumably due to mutual repulsion of
the sterically demanding PR3 and TNP ligands; TNP was reported
at the time of its synthesis to form four-coordinate, square planar
complexes of the type MX2(P,N-TNP), where M = PdII and PtII and
X = halide,5b and catalysts based on Pd-TNP species have been used
for ethylene oligomerization and polymerization of a substituted
Published by NRC Research Press

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Can. J. Chem. Vol. 92, 2014
Scheme 2. Synthetic route to the RuIII−aminophosphine complexes.
PN
2 PR3
'RuCl3'
RuCl3(PR3)2(DMA)
RuCl3(PN)(PR3) ; PN = P-N, (R)-AMPHOS
or RuCl3(BNP)
thiophene.14 Cobalt(II) and nickel(II) complexes containing TNP
are also known.5a
Fig. 4. ORTEP diagram of mer-RuCl3(P−N)(PPh3) (2a) with 33%
probability thermal ellipsoids.
The structures of 2a (Fig. 4), 3·CHCl3 (Fig. 5), and 4a (Fig. 6) all
show distorted octahedral geometry, with mer-chloride ligands. In
2a and 4a, the nitrogen atom is trans to the monodentate phos-
phine; in 3, the BNP ligand is also bonded in a mer-configuration.
Selected bond lengths and angles are given in Tables 4 and 5,
respectively, and they are essentially as expected. In 2a, the major
distortions from the octahedral geometry involve the P1 atom of
the P−N ligand, which shows distortion from orthoganolity up to
ϳ12° and ϳ10° from linearity within the trans-Cl ligands; in 4a, the
corresponding distortions are both ϳ10°, and the trans-Cl–Ru–Cl
angle is 171.6°, which is ϳ5° more than for 2a; in 3, the departure
from orthogonality is only ϳ8°, although the mer-coordination of
BNP leads to a restricted trans-N–Ru–N angle of only 160°. The
aminophosphine ligand in 2a and 4a subtends angles at the ru-
thenium atom of about 79° and 90°, respectively, and in 3, the two
such angles are about 85° and 82°. The C–P–C and C–N–C bond
angles at the coordinated phosphorus and nitrogen atoms are
within ϳ6° of the tetrahedral angle, while those involving coordi-
nation to ruthenium (i.e., C–P–Ru and C–N–Ru) are always greater
than the tetrahedral angle (up to ϳ20°).
The bond lengths are similar to those found within examples of
other RuIII complexes containing phosphorus, nitrogen, or chlo-
ride donor ligands,15 including a related mer-RuCl3-PN-ligand spe-
cies where PN is diphenyl(2-pyridyl)phosphine,15e but interesting
features are evident. The Ru–P and Ru–N bond lengths in 3 are at
least 0.15 Å shorter than the average values of these bond lengths
in 2a and 4a, presumably because of the rigidly bonded mer-BNP.
In 3 also, two chloride ligands, Cl(2) and Cl(3), are weakly hy-
drogen bonded to the hydrogen atom of the CHCl3 solvate with
Cl···H distances of 2.68 and 2.83 Å (Fig. 5) and, as a result, the two
associated Ru–Cl bonds are longer by up to ϳ0.16 Å than the
Ru–Cl(1) bond, although some lengthening of the Ru–Cl(3) bond
results from the strong trans-influence of the phosphorus atom of
the BNP ligand. The same trans influence is seen in the structures
of 2a and 4a, where the relevant Ru–Cl bond is 0.07−0.08 Å longer
than the other two Ru–Cl bonds (Table 4). Finally, the average
values of the trans-Ru–Cl bond lengths in 2a and 4a are ϳ0.05 Å
shorter than the corresponding value found for the RuII analogue,
trans-RuCl2(P–N)(P(p-tolyl3)),9b which seems reasonable in terms of
the difference in oxidation states.
Fig. 5. ORTEP diagram of mer-RuCl3(BNP) (3)·CHCl3 with 33%
probability thermal ellipsoids.
The magnetic moments of complexes 2–4 (1.5 to 2.0 BM) are
consistent with high-spin RuIII species. Of note, the reported com-
plex RuCl3(NO)(P–N) appears analogous to 2a and 2b, but in fact is
a RuII(NO+) species;16 other RuII(P–N)-containing complexes have
been reported.17
Ruthenium(III) precursor complexes
The RuIII−aminophosphine complexes discussed above are the
first monomeric RuIII species to be formed via the useful, easily
synthesized, air-stable RuIII precursors, RuCl3(PR3)2(DMA)·DMA
(1a and 1b). We have previously used these precursors with phos-
phine ligands for formation of monomeric and dimeric RuII
complexes and dimeric RuII/RuIII mixed-valence complexes;4b–4d
and a species that we initially formulated as a RuIII species,
PN ligands, the products are the mixed-valence, triply chloride-
bridged species Ru2Cl5(P-P)2 and the OPR3 oxide, the reduction
process being caused by the presence of trace water.19 The differ-
ence in reactivity of the PN and P–P ligands is attributed to the
␴-donor ability of the amine function that better stabilizes the
RuIII oxidation state. Complexes 1a and 1b are much superior RuIII
2
RuH(PR3)2(␮-Cl)2(␮-H)Ru(H)2(PR3)2,4b was later shown (by us) to be
the first structurally characterized dimeric species to contain a
molecular H2 ligand, and so, it is, in fact, formally a RuII com-
2
plex.18 Of interest, when 1a and 1b are reacted with chelating
bidentate P–P ligands under the identical conditions used for the
Published by NRC Research Press

Mudalige et al.
721
Fig. 6. ORTEP diagram of mer-RuCl3(AMPHOS)(PPh3) (4a) with 50%
probability thermal ellipsoids.
Table 5. Selected bond angles for the mer-complexes RuCl3(P−N)(PPh3)
(2a), RuCl3(BNP) (3), RuCl3(AMPHOS)(PPh3)(4a), and RuCl3(PPh3)(DMA)2·DMA
(1c), with estimated standard deviations in parentheses.
Bond
Angle (°)
Bond
Angle (°)
Complex 2a
Cl(1)−Ru−Cl(2)
Cl(1)−Ru−Cl(3)
Cl(1)−Ru−P(1)
Cl(1)−Ru−P(2)
Cl(1)−Ru−N
175.00 (3)
92.37 (3)
90.15 (3)
88.67 (3)
93.77 (8)
85.37 (3)
83.18 (8)
P(2)−Ru−Cl(3)
P(2)−Ru−Cl(2)
P(2)−Ru−N
P(2)−Ru−P(1)
Cl(3)−Ru−Cl(2)
Cl(3)−Ru−N
Cl(3)−Ru−P(1)
N−Ru−P(1)
84.22 (3)
94.64 (3)
175.38 (8)
105.02 (3)
91.69 (3)
91.75 (8)
170.47 (3)
78.91 (8)
Cl(2)−Ru−P(1)
Cl(2)−Ru−N
Complex 3·CHCl3
Cl(1)−Ru−Cl(2)
Cl(1)−Ru−Cl(3)
Cl(2)−Ru−Cl(3)
Cl(1)−Ru−P
Cl(1)−Ru−N(1)
Cl(1)−Ru−N(2)
Cl(2)−Ru−P
Cl(2)−Ru−N(1)
Complex 4a
Cl(1)−Ru−Cl(2)
Cl(1)−Ru−P(1)
Cl(1)−Ru−P(2)
Cl(1)−Ru−N
Cl(1)−Ru−Cl(3)
Cl(2)−Ru−Cl(3)
Cl(2)−Ru−P(1)
Cl(2)−Ru−P(2)
Complex 1c
O(1)−Ru−P
177.63(6)
87.77 (6)
90.00 (6)
92.13 (6)
98.40 (14)
96.57 (14)
90.09 (5)
82.61 (14)
Cl(2)−Ru−N(2)
Cl(3)−Ru−P
Cl(3)−Ru−N(1)
Cl(3)−Ru−N(2)
P(1)−Ru−N(1)
P(1)−Ru−N(2)
N(1)−Ru−N(2)
82.95 (14)
179.91 (7)
95.51 (14)
98.28 (13)
84.50 (14)
81.74 (13)
159.99 (18)
99.15 (7)
170.08 (7)
85.73 (7)
86.5 (2)
88.53 (7)
171.61 (8)
89.87 (7)
86.00 (7)
Cl(2)−Ru−N
Cl(3)−Ru−P(1)
Cl(3)−Ru−P(2)
Cl(3)−Ru−N
P(1)−Ru−P(2)
P(1)−Ru−N
87.2 (1)
82.24 (7)
98.01 (7)
90.0 (1)
99.09 (7)
89.9 (2)
168.7 (2)
Table 4. Selected bond lengths for the mer-complexes RuCl3(P−N)(PPh3)
(2a), RuCl3(BNP) (3), RuCl3(AMPHOS)(PPh3) (4a), and RuCl3(PPh3)(DMA)2·
DMA (1c), with estimated standard deviations in parentheses.
P(2)−Ru−N
Bond
Length (Å)
Bond
Length (Å)
90.91 (8)
175.15 (9)
88.5 (1)
84.7 (1)
173.9 (1)
89.3 (1)
95.1 (1)
O(1)−Ru−O(2)
P−Ru−Cl(3)
P−Ru−Cl(1)
85.9 (1)
93.69 (4)
90.09 (5)
90.43 (5)
93.01 (5)
93.73 (5)
173.19 (5)
Complex 2a
Ru−Cl(1)
Ru−Cl(2)
O(1)−Ru−Cl(3)
O(1)−Ru−Cl(1)
O(1)−Ru−Cl(2)
O(2)−Ru−P
O(2)−Ru−Cl(3)
O(2)−Ru−Cl(1)
O(2)−Ru−Cl(2)
2.3272 (9)
2.3331 (9)
2.3980 (8)
Ru−P(1)
Ru−P(2)
Ru−N(1)
2.3666 (9)
2.3497 (8)
2.350 (3)
P−Ru−Cl(2)
Ru−Cl(3)
Cl(3)−Ru−Cl(1)
Cl(3)−Ru−Cl(2)
Cl(1)−Ru−Cl(2)
Complex 3·CHCl3
Ru−Cl(1)
Ru−Cl(2)
2.3182 (15)
2.3577 (14)
2.4847 (15)
2.68
Ru−P(1)
Ru−N(1)
Ru−N(2)
Cl(3)···H(23)
2.1995 (13)
2.204 (5)
2.210 (5)
2.83
84.1 (1)
Ru−Cl(3)
Cl(2)···H(23)
Complex 4a
Ru−Cl(1)
Ru−Cl(2)
Ru−Cl(3)
2.398 (2)
2.319 (2)
2.356 (2)
Ru−P(1)
Ru−P(2)
Ru−N(1)
2.401 (2)
2.374 (2)
2.355 (6)
Fig. 7. ORTEP diagram of mer,cis-RuCl3(DMA)2(PPh3)·DMA (1c) with
50% probability thermal ellipsoids.
Complex 1c
Ru−Cl(1)
Ru−Cl(2)
2.345 (1)
2.350 (1)
2.311(1)
Ru−O(1)
Ru−O(2)
Ru−P
2.064 (3)
2.200 (3)
2.273(1)
Ru−Cl(3)
precursors than the commercially variable RuCl3·3H2O, which is a
mixture of RuIII and RuIV compounds.20
To the best of our knowledge, only one other group has used 1a
and 1b as synthetic precursors, the products again being RuII21 or
RuII−RuIII species.22 Worth noting is the accidental isolation of
crystals of mer,cis-RuCl3(DMA)2(PPh3)·DMA (1c) that precipitates
from the filtrate obtained from the synthesis of 1a; one PPh3
ligand of 1a has been replaced by DMA. Attempts to make 1c on
purpose by using a 1:1 PPh3/RuCl3·3H2O reaction in DMA were
surprisingly unsuccessful. The basic octahedral structure of 1c
(Fig. 7), which is less distorted than those of 2a and 4a, reveals
cis-O-bonded DMA ligands and, we believe, is the first reported
for a RuIII−DMA complex. There are structures reported for the
RuII complexes trans,trans-RuCl2(PPh3)2(CO)(DMA)21 and trans,trans-
RuCl2(PCy3)2(H2)(DMA)23 in which the Ru–O bond lengths are
2.149 Å (trans to CO) and 2.323 Å (trans to H2), respectively. The
Ru−O bond lengths in 1c are 2.064 and 2.200 Å and are respectively
trans to a chlorine and a phosphorus atom, the significantly longer
bond resulting from the trans influence of the phosphine ligand.
The geometries of the coordinated DMA in all three structures are
essentially the same and correspond to that found in other tran-
sition metal − DMA complexes.24
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722
Can. J. Chem. Vol. 92, 2014
Scheme 3. Formation of RuII-hydridochloro species from a RuIII precursor; ancillary ligands omitted.
H2
2 RuIIICl3 + H2
2 RuIICl2 + 2 H+Cl-; RuIICl2
(H2)RuIICl2
HRuIICl + H+Cl-
Reactivity of the mer-RuCl3(P–N)(PR3) complexes (2a and 2b)
No reactions were observed on exposure of CH2Cl2 solutions of
the RuIII−aminophosphine complexes (at ϳ10−2 mol L−1) to 1 atm
H2 at r.t.; however, in DMA solution, the initially dark red colour
of 2a (or 2b) rapidly becomes orange−red. The reaction with 2b,
for example, generates a solution whose 31P{1H} spectrum shows
just two species in a ratio of ϳ2:1 that are considered to be
RuCl2(P–N)(P(p-tolyl)3)(DMA) (5) and (␩2-H2)RuCl2(P–N)(P(p-tolyl)3)
Scheme 4. Plausible steps for the HCl/RuCl2(P−N)(PPh3) reaction to
give 2a; P−N is shown in Scheme 1.
P
P
P
N
N
N
HCl
+ 1/2 H2
Cl Ru Cl
Cl Ru Cl
Cl Ru Cl
C6D6
Ph3P
Ph3P
Ph3P
Cl
H
Cl
2a
(6), with respective AX doublet patterns at ␦ 56.6 and 72.4 (2JPP
=
39.9 Hz) and ␦ 53.5 and 59.1 (2JPP = 25.5 Hz). The spectrum for 5
is the same as that seen on dissolution of the known complex
RuCl2(P–N)(P(p-tolyl)3)9b in DMA under argon, and exposure of this
solution to H2 generates essentially the same 2:1 spectrum noted
above; such reactivity with H2 in CH2Cl2, CHCl3, and acetone so-
lutions, is known to generate the molecular H2 derivative.9b,25
Further, when DMA solutions of 2a or 2b are similarly reacted
with H2 in the presence of six equivalents of PS, only one in situ
product is seen in the 31P{1H} spectrum, and this is considered to
be the hydridochloro species Ru(H)Cl(P–N)(PR3), which have been
isolated via reactions of PS with the RuCl2(P–N)(PR3) complexes in
benzene solution;9b,25 the 31P{1H} spectra for both of these com-
plexes in DMA (doublets at ␦ ϳ 86 and ϳ70 with 2JPP ϳ 35 Hz) are
very similar to those seen in the in situ PS reactions. Use of two to
four equivalents of PS in the H2/DMA reaction generates a mixture
of the ␩2-H2 and hydridochloro species, the relative amounts of
the latter increasing with greater PS concentration.
Scheme 4 are reversible and that the production of H2 would
require two RuII (or a RuII2) species. More studies are needed on
this reaction, particularly at low temperature, to confirm the stoi-
chiometry and elucidate mechanistic details. Relevant also is a
report that gives a crystal structure of a PtII complex formulated
[PtClL2·HCl]Cl, where L is the P,N-coordinated aminophosphine
Ph2P(CH2)2N(H)tBu; however, the HCl is present as the proton in
t
an −N(H)2 Bu+ moiety and an associated chloride anion;32
a
related, reversible, solid-state reaction of two equivalents of HCl
with CuCl2L2 (L = 3-chloropyridine) has been shown to give
[HL+]2CuCl42– 33 Such protonation in our system would generate a
.
RuIICl3(P–NH+)(PPh3) intermediate, but we consider this less likely
to result in a redox process to give RuIIICl3(P–N)(PPh3). There is
certainly one paper that reports a one-electron oxidation of a
transition metal (NiI ¡ NiII) with coproduction of H2, and kinetic
data were interpreted in terms of a mechanism essentially involv-
ing initial protonation to form NiIIIH followed by bimolecular
decomposition of this to NiII and H2.34 Processes involving two-
electron oxidative addition of HCl are well known;35 such an
The presence of a base such as DMA26 or PS is required for the
reduction of the RuIII to RuII; this oxidation state allows for for-
mation of the ␩2-H2 complex that, in the presence of PS (a stronger
base than DMA), gives the hydridochloro species The relevant
chemistry is outlined in Scheme 3, in which both the initial and
final steps require base to react with the HCl coproduct. The net
chemistry has been well established within chloro-phosphine
systems,4b,18 but only in the case of the chloro-aminophosphine
systems is there direct evidence for the monomeric ␩2-H2
complex,9b,25 although an ␩2-H2 moiety within dimeric Ru-(chloro)-
phosphine species is well known.18,27 Of note, the RuII species
mentioned in this section (Scheme 3) are all O2 sensitive, and the
in situ synthesis via H2 reduction of RuIII provides a convenient
way for their preparation.
Of significant interest, after our extensive studies on reactions
of the five-coordinate trans-RuCl2(P–N)(PR3) complexes with small
molecules (H2S and thiols,3a H2,9b,25 N2,9b N2O,28 H2O and alco-
hols,29 and CO and NH330), which all form (at least initially) six-
coordinate 1:1 adducts, gaseous HCl was also tested. The red,
crystalline solid isolated from the r.t. reaction of anhydrous HCl
gas with the dark green C6D6 solution of RuCl2(P–N)(PPh3) was
surprisingly mer-RuCl3(P–N)(PPh3) (2a), as discovered via what
turned out to be a duplicate X-ray analysis and then elemental
analysis! We had hoped optimistically for a structure showing a
metal-coordinated HCl, which has yet to be reported, although
Sellman’s group has isolated a RuII(ClH)(PPh3)(“S4”) complex,
where “S4” is a dianionic, tetradentate dithiolate ligand, with
spectroscopic evidence suggesting that the HCl is coordinated as a
chloride ligand with the H+ hydrogen bonded to both the chloride
and a thiolate.31 Noted also in this paper is a reaction where this
RuII species is converted under N2 to RuIIICl(PPh3)(“S4”), with the
speculation that the H+ might be the oxidant. In our reaction,
written speculatively as proceeding via an intermediate with co-
ordinated HCl (Scheme 4), the proton must be the oxidant; unfor-
tunately, the required H2 coproduct was not detected (␦ ϳ 4.5)
because its concentration is low and the solution contains para-
magnetic RuIII. The observations imply that the reaction steps in
initial step in our RuII system would involve formation of a RuIV
−
hydride intermediate, with the RuIII product being formed via a
subsequent bimolecular process. A reviewer suggests that a spe-
cies with coordinated Cl···HCl moiety is also a feasible intermedi-
ate for the reaction of Scheme 4, but we prefer reactivity involving
the vacant site.
Preliminary studies on the other RuIII complexes 3 and 4a and
4b with H2 suggest behaviour similar to that of 2a and 2b. The
systems are active for catalytic hydrogenation of selected olefinic
substrates and imines in C6H6/MeOH mixed solvents at ϳ10 atm
H2; up to 100% conversions can be achieved, but asymmetric in-
duction using 4a and 4b, the chiral AMPHOS species, is minimal
(<10%).36
Conclusions
Synthetic routes to air-stable aminophosphine complexes of
RuIII via easily made RuIII precursors are described; earlier work
has shown that use of phosphine ligands generates RuII or di-
meric RuII/RuIII mixed-valence complexes. Reported here are X-ray
structures of three known aminophosphine ligands, three RuIII
complexes containing aminophosphine ligands, and a precursor-
type RuIII−DMA complex, which is the first structurally reported
N,N=-dimethylactamide complex of RuIII. The aminophosphine
complexes can be reduced in situ by H2 to air-sensitive RuII spe-
cies, this providing a convenient route to the usual +2 oxidation
state of catalytic ruthenium species. The formation of mer-RuCl3-
(P–N)(PPh3) by reaction of RuCl2(P−N)(PPh3) with gaseous HCl pro-
vides a rare example of this reagent acting as an overall one-
electron oxidant.
Supplementary material
Supplementary material is available with the article through
the journal Web site at http://nrcresearchpress.com/doi/suppl/
10.1139/cjc-2013-0539. This provides crystal data for (R)-AMPHOS,
Published by NRC Research Press

Mudalige et al.
723
(h) Alessio, E.; Balducci, G.; Calligaris, M.; Costa, G.; Attia, W. M. G.;
Mestroni, G. Inorg. Chem. 1991, 30, 609. doi:10.1021/ic00004a005;
(i) Jaswal, J. S.; Rettig, S. J.; James, B. R. Can. J. Chem. 1990, 68 (10), 1808.
doi:10.1139/v90-282.
and complexes 4a and 1c, in non-CIF form; the CCDC reference
numbers for BNP, TNP, and complexes 2a and 3·CHCl3 are 962715−
962718, respectively.
(16) daSilva, J. P.; Caetano, F. B.; Cavarzan, D. A.; Fagundes, F. D.; Romualdo, L. L.;
Ellena, J.; Jaworska, M.; Lodowski, P.; Barison, A.; de Araujo, M. P. Inorg.
Chim. Acta 2011, 373, 8. doi:10.1016/j.ica.2011.03.042.
(17) (a) Fagundes, F. D.da; Silva, J. P.; Veber, C. L.; Barison, A.; Pinheiro, C. B.;
Back, D. F.; de Sousa, J. R.; de Araujo, M. P. Polyhedron 2012, 42, 207;
(b) Hounjet, L. J.; Bierenstiel, M.; Ferguson, M. J.; McDonald, R.;
Cowie, M. Inorg. Chem. 2010, 49, 4288; (c) Moreno, M. A.; Haukka, M.;
Jääskeläinen, S.; Vuoti, S.; Pursiainen, J.; Pakkanen, T. A. J. Organomet. Chem.
2005, 690, 3803.
Acknowledgements
We thank the Natural Sciences and Engineering Council of Can-
ada for funding and Colonial Metals Inc. for a loan of RuCl3·3H2O.
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