Reactions of 2-indolylphosphines with Ru3(CO)12: Cluster capping with μ3, η2-indohlyphosphine as an anionic six-electron P,N-donor ligand

Article abstract of DOI:10.1039/b409930c

Stepwise bidentate coordination of the novel indolylphosphine ligands HL (1, HL = P(C₆H₅)₂(C₉H₈N) (diphenyl2-(3-methylindolyl)phosphine); 2, HL = P(C₆H ₅)(C₉H₈N)₂ (phenyldi-2-(3- methylindolyl)phosphine); and 3, HL = P(C₆H₅)(C ₁₇H₁₂N₂) (di(1H-3-indolyl)methane-(2,12)- phenylphosphine)) to the ruthenium cluster Ru₃(CO)₁₂ is demonstrated. Reactions of 1-3 with Ru₃(CO)₁₂ led to the formation of Ru₃(CO)₁₁(HL) (4-6), in which HL is mono-coordinated through the phosphorus atom. The X-ray structures of 4-6 show that the phosphorus atom is equatorially coordinated to the triruthenium core. In all cases, gentle heating of Ru₃(CO)₁₁(HL) resulted in the formation of Ru₃(CO)₉(μ-H)(μ₃, η²-L) (7-9) in which the NH proton of the indolyl substituent had migrated to the ruthenium core to form a bridging hydride ligand. The X-ray structure of Ru₃(CO)₉(μ-H)[μ₃, η²P(C₆H₅)₂(C₉H ₇N)] (7) shows the deprotonated nitrogen atom of the indolyl moiety bridging over the face of the triruthenium core, bonding to the two ruthenium metal centers to which the phosphorus atom is not bound. The phosphorus atom is forced to adopt an axial bonding mode due to the geometry of the indolylphosphine ligand. Cluster electron counting and X-ray data suggest that the indolylphosphine behaves as a six-electron ligand in this mode of coordination. Compounds 4-9 have been characterized by IR, ¹H, ¹³C and ³¹P NMR spectroscopy.

Full text of DOI:10.1039/b409930c

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F U L L P A P E R
Reactions of 2-indolylphosphines with Ru3(CO)12: cluster capping
with l3,g2-indolylphosphine as an anionic six-electron P,N-donor
ligand
Edmond Lam, David H. Farrar,* C. Scott Browning and Alan J. Lough
Davenport Chemical Research Building, University of Toronto, 80 St. George Street, Toronto,
Ontario, Canada, M5S 3H6. E-mail: dfarrar@chem.utoronto.ca; Fax: (+416) 946-7526;
Tel: (+416) 946-7526
Received 30th June 2004, Accepted 16th August 2004
First published as an Advance Article on the web 9th September 2004
Stepwise bidentate coordination of the novel indolylphosphine ligands HL (1, HL = P(C6H5)2(C9H8N) (diphenyl-
2-(3-methylindolyl)phosphine); 2, HL = P(C6H5)(C9H8N)2 (phenyldi-2-(3-methylindolyl)phosphine); and 3,
HL = P(C6H5)(C17H12N2) (di(1H-3-indolyl)methane-(2,12)-phenylphosphine)) to the ruthenium cluster Ru3(CO)12
is demonstrated. Reactions of 1–3 with Ru3(CO)12 led to the formation of Ru3(CO)11(HL) (4–6), in which HL is
mono-coordinated through the phosphorus atom. The X-ray structures of 4–6 show that the phosphorus atom
is equatorially coordinated to the triruthenium core. In all cases, gentle heating of Ru3(CO)11(HL) resulted in the
formation of Ru3(CO)9(l-H)(l3,g2-L) (7–9) in which the NH proton of the indolyl substituent had migrated to the
ruthenium core to form a bridging hydride ligand. The X-ray structure of Ru3(CO)9(l-H)[l3,g2-P(C6H5)2(C9H7N)]
(7) shows the deprotonated nitrogen atom of the indolyl moiety bridging over the face of the triruthenium core,
bonding to the two ruthenium metal centers to which the phosphorus atom is not bound. The phosphorus atom
is forced to adopt an axial bonding mode due to the geometry of the indolylphosphine ligand. Cluster electron
counting and X-ray data suggest that the indolylphosphine behaves as a six-electron ligand in this mode of
coordination. Compounds 4–9 have been characterized by IR, 1H, 13C and 31P NMR spectroscopy.
2-pyridinyl). In these ligands, both the nitrogen and phosphorus
centers serve as two-electron donors.
Introduction
We have recently reported the synthesis of several new
indolylphosphine ligands HL (1, HL = P(C6H5)2(C9H8N) (di-
phenyl-3-methylindolylphosphine); 2, HL = P(C6H5)(C9H8N)2
(phenyldi(3-methylindolyl)phosphine); and 3, HL = P(C6H5)-
(C17H12N2) (di(1H-3-indolyl)methane-(2,12)-phenylphosphine))
in which the phosphorus atom is bound to the C2 position of
the indolyl substituent.1
The 2-indolylphosphines1,4 notwithstanding, diphenyl
(2-pyrrolyl)phosphine, PPh2(2-C4H3NH), is the only P-donor
ligand that features a protic hydrogen on an aromatic substituent.
In addition to its difficult synthesis, its unpredictable coordina-
tion chemistry has hindered investigations into the behavior
of PPh2(2-C4H3NH) as a ligand. Its reaction with Mn2(CO)10
to obtain the complex Mn3(l3-P,N-g5-Ph2PC4H3N)(CO)11
(Scheme 1) in low yield as one of three products5 represents the
only example of an anionic nitrogen centre in a phosphineligand.
In addition to g5-coordination of the azacyclopentadienyl ring
to a manganese tricarbonyl unit, deprotonation of the nitrogen
atom occurs, allowing the diphenyl-2-pyrrolylphosphine ligand
to bridge across the Mn2(CO)8 unit as a four-electron donor.
The synthesis of these ligands was carried out by using a
(dialkylamino)methyl protecting group to direct lithiation at the
C2 position of the indole,2 followed by electrophilic substitution
of a phosphonous acid dichloride (RPCl2) or phosphinous acid
chloride (R2PCl) to give the desired ligand. In the absence of
base with which to deprotonate NH, the coordination of these
ligands to palladium occurred exclusively at the phosphorus
atom.1
Scheme 1
As part of an ongoing examination into the behaviour of the
2-indolylphosphines, we herein report the investigation of the ad-
ditional reactivity of the NH moiety of the indolyl substituents
of the coordinated ligands 1–3. The metal carbonyl cluster
Ru3(CO)12 was chosen as the platform for this study because
of previous studies in the literature in which the reactions
of Ru3(CO)12 with closely related ligands such as PPh2Py are
well characterized. The substitution reactions of monodentate
tertiary phosphine ligands6 to yield Ru3(CO)11L occurs favour-
ably via a radical reaction using sodium diphenylketyl as the
initiator.6a
These 2-indolylphosphines bear closest resemblance to
diphenyl(2-pyrrolyl)phosphine and the 2-pyridinylphosphines.
There are many examples in the chemical literature of P–C–N
bridges across two metal centers using the latter ligands,3
3a
as observed in the complex Pt2Cl2(PPh2Py)2 (where Py =
The Ph2CO− catalyzed reactions between Ru3(CO)12 and
the indolylphosphine ligands 1–3 give the mono-substituted
clusters Ru3(CO)11(HL) (4–6) in which coordination of the
ligand occurs only at the phosphorus atom. These reactions
give very high yields. We then demonstrate the ability of the
indolylphosphine ligand to bridge metal centers in the synthesis
T h i s j o u r n a l i s
©
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
D a l t o n T r a n s . , 2 0 0 4 , 3 3 8 3 – 3 3 8 8
3 3 8 3

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Table 1 Crystallographic and refinement data for clusters 4, 5, 6 and 7·C6D6
4
5
6
7
Empirical formula
M
C32H18NO11PRu3
926.65
C35H21N2O11PRu3
979.72
C34H17N2O11PRu3
963.68
C36H18D6NO9PRu3
948.74
Crystal colour, shape
Crystal size/mm
Crystal system
Space group
Red plate
0.14 × 0.12 × 0.08
Triclinic
Red plate
0.13 × 0.10 × 0.10
Triclinic
Red needle
0.20 × 0.10 × 0.10
Monoclinic
P21/n
Red needle
0.12 × 0.12 × 0.10
Triclinic
P1
P1
P1
a/Å
b/Å
c/Å
a/°
9.9970(2)
11.4500(2)
14.8620(4)
100.723(1)
95.278(1)
100.585(1)
1628.96(6)
2
8.4910(2)
12.7190(3)
16.6940(3)
88.873(1)
78.824(1)
88.770(1)
1768.08(7)
2
9.2360(3)
35.246(1)
10.4650(4)
90
95.060(2)
90
3393.4(2)
4
1.886
10.4643(3)
10.9306(3)
15.8905(5)
106.70(1)
94.64(1)
91.27(1)
1733.26(9)
2
b/°
c/°
V/Å3
Z
Dc/g cm−3
1.889
1.84
1.818
F(000)
904
1.484
960
1.373
1880
1.43
932
1.393
0 to 13
l(Mo-Ka)/cm−1
Limiting indices, hkl
−12 to 12
−14 to 14
−17 to 19
2.67–27.47
0.892, 0.699
18107
7390/435
0.0008(2)
435
−10 to 11
−16 to 16
−20 to 21
2.90–27.51
0.885, 0.510
19589
8047/0.0554
0.0009(3)
472
−11 to 11
−45 to 45
−11 to 13
2.61–27.50
0.868, 0.783
17172
7717/0.0438
none
460
−14 to 14
−20 to 20
2.67–27.34
0.8733, 0.8507
13967
7390/0.161
0.0065(7)
457
h Range/°
Max. and min. transmission
No. of reflections collected
No. of independent reflections/Rint
Extinction coefficient
No. of refined parameters
Final R1, wR2
0.0362, 0.0788
0.0549, 0.0880
1.058
0.0371, 0.0850
0.0526, 0.0938
1.041
0.0411, 0.0785
0.0783, 0.0923
1.039
0.0481, 0.1230
0.0757, 0.1442
1.047
Final R1, wR2 (all data)
Goodness of Fit
Dqmin,max/e Å−3
−0.989, 1.576
−1.327, 1.400
−0.822, 0.732
−1.434, 1.947
of Ru3(CO)9(l-H)(l3,g2-L) (7–9). The resulting negatively
charged nitrogen atom of the indolyl group axially bonds to two
ruthenium atoms as a four-electron donor. We have been able
to isolate the mono-substituted indolyl clusters Ru3(CO)11(HL)
in good quantities without ligand fragmentation and subse-
quently effect their conversion to Ru3(CO)9(l-H)(l3,g2-L) in a
controlled, stepwise manner. A discussion of the bonding mode
of the novel six-electron indolylphosphine ligand is described in
the crystal structure of Ru3(CO)9(l-H)[(l3,g2-P(C6H5)2(C9H7N)]
protonated. The broadness of the single peak at d 204.2 ppm
in the 13C NMR suggested that the carbonyl ligands of the
ruthenium cluster are fluxional in solution.
X-Ray quality crystals of 4 were grown from a saturated
hexanes solution of the cluster. An ORTEP representation is
given in Fig. 1. Crystallographic data for the crystal 4 is provided
in Table 1. A selection of bond distances and angles is given in
Table 2.
(7). The compounds 4–9 have been characterized by IR, 1H, 13
C
and 31P NMR spectroscopy.
Results and discussion
Synthesis and characterization of Ru3(CO)11(HL) (4–6)
The 48-electron, red and air-stable mono-substituted cluster 4
was efficiently prepared by addition of a catalytic amount of
Ph2CO− into a 1:1 orange coloured solution of Ru3(CO)12 and
1 in THF at 40 °C (eqn. (1)).
Fig. 1 ORTEP drawing of Ru3(CO)11[(P(C6H5)2(C9H8N)] 4 with atoms
shown as 30% probability ellipsoids. Phenyl hydrogen atoms have been
omitted for clarity.
(1)
The reaction was complete within 5 min. The mCO absorption
pattern of 4 was consistent with that of other previously char-
acterized mono-substituted tertiary phosphine ruthenium
clusters such as Ru3(CO)11(PPh3).6a Coordination of the indolyl-
phosphine to the ruthenium cluster resulted in a downfield shift
in the 31P NMR spectrum from d −33.1 ppm for the free ligand 1
to d 15.9 ppm for the cluster. The absence of any metal–hydride
resonances in the 1H NMR and a signal at d 8.83 ppm for the NH
proton confirmed that the nitrogen atom on the indole remained
The crystal structure confirms substitution of a carbonyl
group by the indolylphosphine 1 in the triruthenium core. P(1)
is bonded equatorially to the Ru(1) atom with a bond length of
2.3665(9) Å. The Ru(1)–P(1) bond length is comparable to the
Ru–P bond length of 2.380(6) Å for Ru3(CO)11(PPh3) in which
the phosphorus atom is similarly bonded equatorially to the
ruthenium cluster.7 Eleven carbonyl ligands complete the ligand
shell of the cluster. The NH proton was found in the difference
3 3 8 4
D a l t o n T r a n s . , 2 0 0 4 , 3 3 8 3 – 3 3 8 8

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Table 2 Selected bond distances (Å) and bond angles (°) for clusters
4–6
4
5
6
Ru(1)–Ru(2)
Ru(1)–Ru(3)
Ru(2)–Ru(3)
Ru(3)–P(1)
N(1)–C(12)
N(1)–C(19)
P(1)–C(12)
C(12)–C(13)
C(13)–C(14)
C(14)–C(19)
2.8628(7)
2.9014(7)
2.8648(7)
2.3665(9)
1.389(4)
1.380(4)
1.818(4)
1.372(5)
1.426(5)
1.417(5)
2.8449(4)
2.8693(7)
2.8411(7)
2.3597(9)
1.389(4)
1.381(4)
1.809(3)
1.376(5)
1.448(5)
1.402(5)
2.8604(5)
2.8894(5)
2.8641(5)
2.343(1)
1.394(4)
1.381(5)
1.800(4)
1.367(5)
1.429(5)
1.407(5)
Ru(1)–Ru(2)–Ru(3)
Ru(1)–Ru(3)–Ru(2)
Ru(2)–Ru(1)–Ru(3)
Ru(1)–P(1)–C(12)
P(1)–C(12)–N(1)
C(12)–N(1)–C(19)
C(12)–C(13)–C(14)
C(13)–C(14)–C(19)
C(14)–C(19)–N(1)
60.87(1)
59.532(9)
59.60(1)
117.7(1)
122.6(2)
109.4(3)
107.2(3)
107.6(3)
106.8(3)
60.612(9)
59.760(9)
59.628(9)
113.5(1)
119.6(3)
103.3(4)
106.5(3)
107.3(3)
107.7(3)
60.63(1)
59.62(1)
59.75(1)
111.5(1)
121.8(3)
108.4(3)
107.2(3)
107.3(3)
107.8(3)
Fig. 2 ORTEP drawing of Ru3(CO)11[P(C6H5)(C9H8N)2] 5 with atoms
shown as 30% probability ellipsoids. Phenyl hydrogen atoms have been
omitted for clarity.
Fourier map confirming that the indole nitrogen atom of the
ligand remains protonated.
In adopting a terminal, equatorial mode of coordination
in 4, 1 serves as a classic monodentate P-donor ligand. This
behaviour lies in contrast to the reactivity observed for PPh2(2-
C4H3NH) and PPh2Py toward Ru3(CO)12.8,9 In both cases, the
mono-substituted Ru3(CO)11L clusters were not isolated in
good yields as they undergo further reaction under ambient
conditions (vide infra).
The analogous clusters 5 and 6 were prepared in similar
fashion and exhibit comparable mCO IR absorption patterns
to 4.
Fig. 3 ORTEP drawing of Ru3(CO)11[P(C6H5)(C17H12N2)] 6 with
atoms shown as 30% probability ellipsoids. Phenyl hydrogen atoms have
been omitted for clarity.
Synthesis and characterization of Ru3(CO)9(l-H)(l3,g2-L) (7–9)
The extensive H-bonding involving the indole substituents
of ligands 1–3 in their palladium complexes1 corroborated
our belief that the NH group would serve as an additional
site of reactivity in these ligands. Metallation of coordinated
phosphines in trinuclear clusters of Group 8 metals has occurred
previously at elevated temperatures.10,11 Decarbonylation of
Os3(CO)11(PPh2Me) in refluxing octane led to the formation of
six products, one of which was Os3H(C6H4PMePh)(CO)9 where
the l3-phosphine is bound through phosphorus at one osmium
center and through the metallated phenyl ring to the remaining
twoosmiumcenters.10 Similarly,pyrolysisof Ru3(CO)10(diphenyl-
phosphinoferrocene) afforded Ru3(l-H){l3-PPh(g1,g2-C6H4)(g-
C5H4)–Fe(g-C5H4PPh2)}(CO)8 in low yield as one of eighteen
products.11
Ligands 2 and 3 also exhibited similar downfield changes
in their 31P NMR chemical shifts as 1 upon bonding to the
triruthenium core. The absence of any metal–hydride resonances
in the 1H NMR spectrum suggested that the NH proton had not
been transferred to the cluster. X-Ray quality crystals of 5 and 6
were also grown from saturated hexanes solutions of the clusters
to confirm the structure of both. ORTEP representations of 5
and 6 are shown in Figs. 2 and 3, respectively.
Crystallographic data for the crystals of 5 and 6 are given
in Table 1. A selection of bond distances and angles for
both crystals is presented in Table 2. Similarly to 4, electron
difference maps demonstrate that the indole nitrogens in 5 and
6 remain protonated. In 5 and 6, P(1) is bonded equatorially
to Ru(1). Intermolecular hydrogen bonding exists in 5 between
N(1)–H(1A) of one cluster and carbonyl O(6) of its crystallo-
graphic partner in the unit cell. Two sets of hydrogen bonding
interactions are present in the crystal lattice of 6. N(1)–H(1A)
hydrogen bonds intramolecularly with carbonyl O(1) while
N(2)–H(2A) hydrogen bonds intermolecularly with carbonyl
O(6) as observed in 5. Hydrogen bonding between NH of the
phosphine and chloride ligands of palladium was previously
reported in the crystal structures of Pd2Cl4[P(C6H5)2(C9H8N)]2,
Pd2Cl4[P(C6H5)(C9H8N)2]2 and Pd2Cl4[P(C6H5)(C17H12N2)]2.1 As
with 1, the ligands 2 and 3 serve as classic monodentate two-
electron P-donors upon substitution of Ru3(CO)12.
The gentle heating of cluster 4 in hexanes at 70 °C (eq. 2)
was monitored by IR spectroscopy. The characteristic mCO IR
absorption of 4 disappeared, leading to a new series of mCO IR
absorptions for Ru3(CO)9(l-H)[(l3,g2-P(C6H5)2(C9H7N)], 7, that
remained unchanged after 4 h of heating.
D a l t o n T r a n s . , 2 0 0 4 , 3 3 8 3 – 3 3 8 8
3 3 8 5

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Table 3 Selected bond distances (Å) and angles (°) for cluster 7·C6D6
Ru(1)–Ru(2)
Ru(1)–Ru(3)
Ru(2)–Ru(3)
Ru(1)–P(1)
Ru(2)–N(1)
Ru(3)–N(1)
N(1)–C(10)
N(1)–C(18)
P(1)–C(10)
C(10)–C(11)
C(11)–C(13)
C(13)–C(18)
Ru(2)–H(1Ru)
Ru(3)–H(1Ru)
2.8026(7)
2.8068(7)
2.7848(7)
2.377(1)
2.191(4)
2.168(4)
1.446(6)
1.434(6)
1.797(5)
1.37(1)
Ru(1)–Ru(2)–Ru(3)
Ru(1)–Ru(3)–Ru(2)
Ru(2)–Ru(1)–Ru(3)
Ru(1)–P(1)–C(10)
P(1)–C(10)–N(1)
C(10)–N(1)–C(18)
C(10)–N(1)–Ru(2)
C(10)–N(1)–Ru(3)
Ru(2)–N(1)–Ru(3)
Ru(3)–Ru(2)–N(1)
Ru(2)–Ru(3)–N(1)
C(10)–C(11)–C(13)
C(11)–C(13)–C(18)
C(13)–C(18)–N(1)
Ru(2)–H(1Ru)–Ru(3)
60.31(2)
60.16(2)
59.53(2)
109.5(2)
114.5(3)
103.3(4)
117.3(3)
116.8(3)
79.4(1)
49.9(1)
50.7(1)
105.7(4)
108.4(4)
110.2(5)
93(3)
(2)
1.451(7)
1.386(8)
1.83(7)
A single broad resonance at d −11.2 ppm and the absence of
1
an indolyl NH resonance in the H NMR spectrum suggested
a net migration of a hydrogen atom to the triruthenium core.12
An X-ray structure determination of 7, a dark-red, air-stable
solid was undertaken to determine the mode of ligand bonding
and the position of the hydride in the cluster since the hydride
resonance was too broad to exhibit 31P-coupling.
2.00(7)
triruthenium core to the remaining two ruthenium metals.12,13
In both instances, the hydride ligand is situated trans to the
deprotonated nitrogen atom.
Red needles of the cluster were grown from a solution of 7 in
MeOH–hexanes (1:1) at −5 °C over three weeks. Benzene-d6,
used as a solvent during prior NMR analysis of this sample,
co-crystallized with the cluster. An ORTEP representation is
given in Fig. 4. Crystallographic data for the crystal 7·C6D6 is
presented in Table 1 and a selection of bond distances and angles
is given in Table 3. The triangular core of three ruthenium atoms
is retained in the cluster. The ligand spans all three ruthenium
atoms so as to cap one face of the triruthenium core. The P(1)
atom, which was bound equatorially to Ru(1) in 4, bonds
axially to the Ru(1) atom of 7. The Ru(1)–P(1) bond length
of 2.377(1) Å is comparable to the Ru(1)–P(1) bond length of
2.3665(9) Å in 4. The planar indolyl group effectively bisects the
cluster in an orientation that is almost perpendicular (dihedral
angle 88.9(1)°) to the triruthenium plane. Its N(1) atom is bonded
axially and symmetrically to both Ru(2) and Ru(3) atoms with
bond lengths of 2.191(4) and 2.168(4) Å, respectively. The
Ru(2)–N(1)–Ru(3) bond angle is 79.4(1)°. The bridging hydride
ligand H(1Ru) was located spanning the Ru(2)–Ru(3) edge of
the metal triangle, sitting trans to the l3,g2-P(C6H5)2(C9H7N)
ligand. the Ru(2)–H(1Ru)–Ru(3) plane lies 60(2)° away from
the plane of the triruthenium core; the Ru(2)–H(1Ru)–Ru(3)
angle is 93(3)°. Nine carbonyl groups complete the ligand shell
of the cluster.
We propose that the indolyl substituent similarly acts as
a four-electron donor in 7. The N(1)–C(10) and N(1)–C(18)
bonds of length 1.446(6) and 1.434(6) Å, respectively, are
significantly longer that the corresponding bonds in 1 (1.399(2)
and 1.373(2) Å), in 4 (1.389(4) and 1.380(4) Å), as well as when
P-bound in the dimer Pd2Cl4[P(C6H5)2(C9H8N)]2 (1.380(4) and
1.366(4) Å).1 These bond lengths more closely resemble those
of aromatic-C–four coordinate-N single bonds (average bond
length = 1.465(7) Å)14 and are significantly longer than the
analogous pyrrolo-pyridinate N–C bonds of Ru3(CO)9(l-H)-
(l3,g2-ppy) in which the disruption of ligand aromaticity is also
reported.13 The nitrogen centre in 7 is therefore best considered
as an sp3-hybridized centre which donates four electrons in a
48-electron cluster. The ability of 1 to behave as an anionic
six-electron l3,g2-P,N-donor polydentate ligand has been also
observed in the formation of the novel cluster Pd4Cl4[P(C6H5)2-
(C9H8N)]2[l3,g2-P(C6H5)2(C9H7N)]2.15
Despite their common bonding features, the controlled
metallation of 1 to cap the Ru3 core is not observed in the
subsequent reactions of the transient Ru3(CO)11L clusters of
PPh2(2-C4H3NH) and PPh2Py. Rather, Ru3(CO)11(PPh2Py)
spontaneously converts at room temperature into Ru3(l,g2-
C(O)Ph)[l3,g2-P(Ph)(C5H4N)](CO)9 (Scheme 2)9 which features
a bridging acyl group as a result of P–C bond cleavage. The
cluster Ru3(CO)11[Ph2P(2-C4H4N)] was isolated in only small
quantities as it readily loses carbonyl ligands to allow for metal-
lation at the pyrrolyl ring to form Ru3(CO)9(l-H)(l3-C4H3N)
(Scheme 3).8 Notably, metallation of the pyrrolyl ring occurs at
the C3 position, not at the nitrogen centre.
Fig. 4 ORTEP
drawing
of
Ru3(CO)9(l-H)[l3,g2-P(C6H5)2-
(C9H7N)]·C6D6 (7·C6D6) with atoms shown as 30% probability ellipsoids.
Phenyl hydrogen atoms and C6D6 have been omitted for clarity.
The solid-state structure of 7 most closely resembles that
of Ru3(CO)9(l-H)(l3,g2-anpy) where anpy = 2-anilinopyridine
and Ru3(CO)9(l-H)(l3,g2-ppy) where ppy = pyrrolo[2,3-b]-
pyridine.12,13 Both products were prepared by reactions of the
ligands with Ru3(CO)12 in refluxing hydrocarbon solvents.
In neither case were intermediates or products with mono-
coordinated ligands identified.
Scheme 2
The analogous clusters 8 and 9 were synthesized in a manner
similarto7andexhibitcomparablemCO IRabsorptionfrequencies
1
The anpy and ppy ligands adopt a similar geometry to that
of 1 and, as anionic six-electron N,N-donors, bridge across the
and relative intensities to 7. The H NMR spectra of 8 and 9
showed broad resonances at d −11.2 and −11.9 ppm, respec-
3 3 8 6
D a l t o n T r a n s . , 2 0 0 4 , 3 3 8 3 – 3 3 8 8

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ties) with hydrogen atoms bonded to carbon atoms included in
the calculated positions and treated as riding atoms.
CCDC reference numbers 243366–243369.
See http://www.rsc.org/suppdata/dt/b4/b409930c/ for crystal-
lographic data in CIF or other electronic format.
Scheme 3
Ru3(CO)11[P(C6H5)2(C9H8N)] 4. A mixture of Ru3(CO)12
(100 mg, 0.156 mmol) and 1 (30 mg, 0.159 mmol) in anhydrous
tetrahydrofuran (12 mL) was heated to 40 °C to dissolve the
cluster. A sodium benzophenone ketyl solution (five drops) was
added dropwise via syringe until the solution became dark red.
The reaction was monitored by IR spectroscopy until comple-
tion. After 15 min, the solvent was removed in vacuo, leaving
a red residue. The product was separated by column chromato-
graphy with an eluent of hexanes–dichloromethane (3:1). The
first orange band was found to be Ru3(CO)12 while the second
red band was found to be the product. Removal of the solvent
from the second band gave a red solid (123 mg, 85%). Red plates
suitable for a single-crystal X-ray diffraction study were grown
by evaporation of a saturated hexanes solution of the cluster at
room temperature over 8 h. 31P{1H} NMR (CD2Cl2): d 15.9 (s).
1H NMR (CD2Cl2): d 8.34 (br s, 1H, NH), 7.21–7.71 (m, 14H)
and 1.95 (s, 3H, CH3 on indole). 13C{1H} NMR (CD2Cl2): d 204.2
tively, consistent with a hydride ligand bridging two ruthenium
atoms in triruthenium clusters.12 Broad NH resonances at d 8.38
and 8.48 ppm, respectively, remain, indicating that indolyl
metallation involves only one of the indolyl substituents while
the other remains protonated. Based on the spectroscopic data,
complexes 8 and 9 also represent 48-electron clusters with
anionic six-electron l3,g2-P(C6H5)(C9H8N)(C9H7N) and l3,g2-
P(C6H5)(C17H11N2) bridging ligands, respectively.
4
1
(br s, CO), 137.2 (d, C8, JCP = 8 Hz), 133.8 (d, Ph–Ci, JCP
=
=
47 Hz), 132.2 (d, Ph–Co, 2JCP = 12 Hz), 130.8 (d, Ph–Cp, 4JCP
2 Hz), 130.0 (d, C9, 3JCP = 8 Hz), 129.0 (d, Ph–Cm, 3JCP = 11 Hz),
3
1
124.3 (s, C6), 123.5 (d, C3, JCP = 60 Hz), 120.6 (d, C2, JCP
=
8 Hz), 120.2 (s, C5), 119.5 (s, C4), 111.4 (s, C7) and 10.7 (s,
CH3 on indole). IR (mCO, cm−1, CH2Cl2): 2099 (m), 2048 (s) and
2014 (m). Anal. Calc. for C32H18NO11PRu3: C, 41.48; H, 1.96; N,
1.51. Found: C, 41.62; H, 2.01; N, 1.39%.
Summary
The present study has demonstrated two coordination modes
for indolylphosphine ligands. These ligands can serve as
monodentate two-electron P-donors in substitution reactions
with Ru3(CO)12. X-Ray structures of the Ru3(CO)11(HL) clusters
confirm l1 and equatorial coordination of the phosphorus atom
to the triruthenium core. Unlike the Ru3 complexes of related
P,N-donor ligands, gentle heating of the monosubstituted
clusters is required to effect further reaction. This has permit-
ted a degree of control over metallation of the indolyl moiety
in capping the cluster to form Ru3(CO)9(l-H)(l3,g2-L) clusters
without ligand fragmentation. The ligands in these com-
pounds behave as novel and robust polydentate six-electron
P,N-donors.
Ru3(CO)11[P(C6H5)(C9H8N)2] 5. In anhydrous tetrahydrofuran
(12 mL), a solution of Ru3(CO)12 (110 mg, 0.172 mmol) and 2
(60 mg, 0.163 mmol) was heated to 40 °C to dissolve the cluster.
The product was prepared in the same manner as 4 to give a
red solid (139 mg, 87%). Red plates suitable for a single-crystal
X-ray diffraction study were grown by evaporation of a satu-
rated hexanes solution of the cluster at room temperature over
10 h. 31P{1H} NMR (CD2Cl2): d −1.48 (s). 1H NMR (CD2Cl2):
d 8.26 (br s, 2H, NH), 7.00–7.75 (m, 13H) and 2.08 (s, 6H, CH3
on indole). 13C{1H} NMR (CD2Cl2): d 203.9 (br s, CO), 137.2
4
1
(d, C8, JCP = 8 Hz), 133.2 (d, Ph–Ci, JCP = 50 Hz), 131.6 (d,
2
3
Ph–Co, JCP = 12 Hz), 130.9 (s, Ph–Cp), 130.0 (d, C9, JCP
=
3
8 Hz), 129.2 (d, Ph–Cm, JCP = 11 Hz), 124.4 (s, C6), 121.9 (d,
C3, 3JCP = 62 Hz), 120.5 (d, C2, 1JCP = 8 Hz), 120.3 (s, C5), 119.5
(s, C4), 111.6 (s, C7) and 10.3 (s, CH3 on indole). IR (mCO, cm−1,
CH2Cl2): 2100 (m), 2050 (s) and 2017 (m). Anal. Calc. for
C35H21N2O11PRu3: C, 42.91; H, 2.16; N, 2.86. Found: C, 42.89;
H, 2.17; N, 2.75%.
Experimental
General procedures
All reactions and manipulations were carried out under an
atmosphereof nitrogenusingstandardSchlenktechniquesunless
otherwise stated. Ru3(CO)12 (Strem), sodium (ACP Chemicals)
and benzophenone, dichloromethane, hexanes and methanol
(Caledon) were used as received. Tetrahydrofuran was distilled
from dark purple solutions of sodium benzophenone ketyl
under a nitrogen atmosphere. Preparation of sodium benzo-
phenyl ketyl catalyst,6b P(C6H5)2(C9H8N) (1),1 P(C6H5)(C9H8N)2
(2),1 and P(C6H5)(C17H12N2) (3)1 were according to literature
methods. All 1H, 13C{1H} and 31P{1H} NMR were recorded on
Varian XL 400 and Varian Mercury 300 spectrometers and ref-
erenced to 85% H3PO4 and SiMe4 (TMS) in CDCl3. IR spectra
were recorded on a Nicolet 550 Magna FTIR spectrophotom-
eter in absorbance mode. Elemental analyses were performed
by ANALEST, Toronto, ON. X-Ray data were collected on a
Nonius Kappa CCD diffractometer using graphite monochro-
mated Mo-Ka radiation (k = 0.71073 Å). A combination of 1° 
and x (with j offsets) scans were used to collect sufficient data.
The data frames were integrated and scaled using the Denzo-
SMN package. The structures were solved and refined with the
SHELXTL-PC v5.1 software package. Refinement was by full-
matrix least squares on F2 using data (including negative intensi-
Ru3(CO)11[P(C6H5)(C17H12N2)] 6. A solution of Ru3(CO)12
(96 mg, 0.150 mmol) and 3 (50 mg, 0.142 mmol) in anhydrous
tetrahydrofuran (12 mL) was heated to 40 °C to dissolve the
cluster. The product was prepared in the same manner as 4
to give a red solid (112 mg, 82%). Red needles suitable for a
single-crystal X-ray diffraction study were grown by evapora-
tion of a saturated hexanes solution of the cluster at room
1
temperature over 6 h. 31P{1H} NMR (CD2Cl2): d −13.9 (s). H
NMR (CD2Cl2): d 8.28 (br s, 2H, NH), 7.10–7.93 (m, 13H), 4.54
2
4
(dd, 1H, CH2 bridge, JHH = 21 Hz, JHP = 5 Hz) and 4.42 (dd,
1H, CH2 bridge, JHH = 21 Hz, JHP = 5 Hz). 13C{1H} NMR
2
4
(CD2Cl2): d 204.0 (br s, CO), 139.33 (d, C8, 3JCP = 8 Hz), 133.8
1
2
(d, Ph–Ci, JCP = 43 Hz), 132.3 (d, Ph–Co, JCP = 14 Hz), 131.6
(d, Ph–Cp, 4JCP = 3 Hz), 129.3 (d, Ph–Cm, 3JCP = 11 Hz), 126.4 (d,
C9, 3JCP = 7 Hz), 126.2 (d, C2, 1JCP = 17 Hz), 124.3 (s, C6), 120.6
(s, C4), 119.6 (s, C5), 122.0 (d, C3, 2JCP = 5 Hz), 111.7 (s, C7) and
20.9 (s, CH2 bridge). IR (mCO, cm−1, CH2Cl2): 2097 (m), 2048 (s)
and 2014 (m). Anal. Calc. for C34H17N2O11PRu3: C, 42.38; H,
1.78; N, 2.91. Found: C, 42.04; H, 1.84; N, 3.19%.
D a l t o n T r a n s . , 2 0 0 4 , 3 3 8 3 – 3 3 8 8
3 3 8 7

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Ru3(CO)9(l-H)[l3,g2-P(C6H5)2(C9H7N)] 7. When 4 (50 mg,
0.054 mmol) was heated at 70 °C in hexane (10 mL), a dark
brown solution formed. Monitoring by IR spectroscopy in
the mCO region revealed complex formation with 100% spectro-
scopic yields within 4 h. The solvent was then removed in
vacuo, leaving a brown residue. The product (first band)
was separated by column chromatography with an eluent of
hexanes–acetone (4:1), giving a brown–red solid. The powder
was recrystallized from methanol–hexanes (1:1) at −5 °C over
3 weeks to give red needles suitable for a single-crystal X-ray
diffraction study (24 mg, 52%). 31P{1H} NMR (CD2Cl2):
d 21.6 (s). 1H NMR (CD2Cl2): d 7.02–7.87 (m, 14H), 2.20 (s, 3H,
CH3 on indole) and −11.1 (s, Ru–H). IR (mCO, cm−1, CH2Cl2):
2083 (m), 2057 (s), 2028 (s) and 2003 (m). Anal. Calc. for
C30H18NO9PRu3: C, 41.39; H, 2.08; N, 1.61. Found: C, 41.70;
H, 2.06; N, 1.54%.
C32H17N2O9PRu3: C, 42.34; H, 1.89; N, 3.09. Found: C, 42.38;
H, 1.79; N, 2.90%.
Acknowledgements
We thank Mr Dan Mathers for performing elemental analyses.
The study was supported by the University of Toronto Open
Fellowship.
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1
solid (23 mg, 49%). 31P{1H} NMR (benzene-d6): d 1.82 (s). H
NMR (benzene-d6): d 8.38 (s, 1H, NH) 7.09–7.74 (m, 13H),
1.82 (s, 3H, CH3 on indole) and −11.2 (s, Ru–H). IR (mCO, cm−1,
CH2Cl2): 2070 (m), 2045 (s), 2020 (s) and 1992 (m). Anal. Calc.
for C33H21N2O9PRu3: C, 42.91; H, 2.29; N, 3.03. Found: C, 42.61;
H, 2.23; N, 2.75%.
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Ru3(CO)9(l-H)[l3,g2-P(C6H5)(C17H11N2)] 9.
A
brown
solution formed when 6 (50 mg, 0.052 mmol) was heated at
75 °C in hexane (10 mL). The reaction was monitored by IR
spectroscopy in the mCO region for 5 h. The solvent was then
removed in vacuo, leaving a purple–brown residue. The product
was separated by column chromatography as the fourth band
with an eluent of hexanes–acetone (4:1) and further purified
with an eluent of hexanes–dichloromethane (1 :1) as the first
band, giving a purple–brown solid (22 mg, 46%). 31P{1H} NMR
(benzene-d6): d −11.9 (s). 1H NMR (benzene-d6): d 8.43 (s, 1H,
2
NH), 7.05–7.47 (m, 13H), 4.59 (dd, 1H, CH2 bridge, JHH
=
4
2
22 Hz, JHP = 5 Hz), 4.47 (dd, 1H, CH2 bridge, JHH = 22 Hz,
4JHP = 5 Hz) and −11.9 (s, Ru–H). IR (mCO, cm−1, CH2Cl2):
2081 (m), 2050 (s), 2030 (s) and 2007 (m). Anal. Calc. for
3 3 8 8
D a l t o n T r a n s . , 2 0 0 4 , 3 3 8 3 – 3 3 8 8