The carboxylate-bridged polymer [{Ru2[μ-η2-OC(R)O]2(CO) 4}n] (R = H, Me or Et) as a synthon in the synthesis of dinuclear phosphorus pyridyl-, quinolyl- and bipyridyl-bridged derivatives of ruthenium(I)

Article abstract of DOI:10.1039/a701897e

Treatment of [{Ru₂[μ-η²-OC(R)O]₂(CO) ₄}_n] or its acetonitrile adduct [Ru₂{μ-η²-OC(R)O}₂(CO) ₄(MeCN)₂] (R = H, Me or Et) with a two-fold molar equivalent of the phosphorus-nitrogen ligands 2-diphenylphosphinopyridine (dppy), 2-diphenylphosphinoquinoline (dpquin) and 6-diphenylphosphino-2,2′-bipyridine (dpbipy) in alcohol under reflux resulted in the formation of dinuclear products of the type [Ru₂{μ-η²-OC(R)O}₂(CO) ₄-(PPh₂R′)₂] (R′ = pyridyl, quinolyl or bipyridyl) in which the PPh₂R′ ligands are monodentate, co-ordinating axially through the phosphorus donor atoms, as established X-ray crystallographically for [Ru₂{μ-η²-OC(Me)O}₂-(CO) ₄(dppy)₂]. On the other hand reaction of [{Ru₂(μ-η²-OC(R)O]₂(CO) ₄}_n] with 2 molar equivalents of dppy or dpquin in toluene under reflux in the presence of NH₄PF₆ and under a slight pressure of carbon monoxide afforded products of the type [Ru₂{μ-η²-OC(R)O}(CO)₄(μ-dppy) ₂]PF₆ or [Ru₂{μ-η²-OC(R)O}(CO)₄(μ-dpquin) ₂]-PF₆ in which the dppy or dpquin ligands adopt the bridging co-ordination mode, this mode of co-ordination being confirmed through a crystal structure determination on [Ru₂{μ-η²-OC(H)O}(CO)₄(μ-dppy) ₂]PF₆. Reaction of [{Ru₂(μ-η²-OC(R)O]₂(CO) ₄}_n] with dpbipy in n-butanol under reflux likewise afforded products, isolated as their hexafluorophosphate salts, in which the phosphorus-nitrogen ligands are bridging, viz. [Ru₂{μ-η²-OC(R)O}-(CO) ₂(μ-dpbipy)₂]PF₆, the structure of [Ru₂{μ-η²-OC(Me)O}(CO) ₂(μ-dpbipy)₂]PF₆ being established X-ray crystallographically.

Full text of DOI:10.1039/a701897e

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The carboxylate-bridged polymer [{Ru2[ì-ç2-OC(R)O]2(CO)4}n]
(R ؍ H, Me or Et) as a synthon in the synthesis of dinuclear
phosphorus pyridyl-, quinolyl- and bipyridyl-bridged derivatives of
ruthenium(I)
John S. Field, Raymond J. Haines* and Campbell J. Parry
Department of Chemistry, University of Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209,
Republic of South Africa
Treatment of [{Ru2[µ-η2-OC(R)O]2(CO)4}n] or its acetonitrile adduct [Ru2{µ-η2-OC(R)O}2(CO)4(MeCN)2]
(R = H, Me or Et) with a two-fold molar equivalent of the phosphorus–nitrogen ligands 2-diphenylphosphino-
pyridine (dppy), 2-diphenylphosphinoquinoline (dpquin) and 6-diphenylphosphino-2,2Ј-bipyridine (dpbipy) in
alcohol under reflux resulted in the formation of dinuclear products of the type [Ru2{µ-η2-OC(R)O}2(CO)4-
(PPh2RЈ)2] (RЈ = pyridyl, quinolyl or bipyridyl) in which the PPh2RЈ ligands are monodentate, co-ordinating
axially through the phosphorus donor atoms, as established X-ray crystallographically for [Ru2{µ-η2-OC(Me)O}2-
(CO)4(dppy)2]. On the other hand reaction of [{Ru2[µ-η2-OC(R)O]2(CO)4}n] with 2 molar equivalents of dppy or
dpquin in toluene under reflux in the presence of NH4PF6 and under a slight pressure of carbon monoxide
afforded products of the type [Ru2{µ-η2-OC(R)O}(CO)4(µ-dppy)2]PF6 or [Ru2{µ-η2-OC(R)O}(CO)4(µ-dpquin)2]-
PF6 in which the dppy or dpquin ligands adopt the bridging co-ordination mode, this mode of co-ordination
being confirmed through a crystal structure determination on [Ru2{µ-η2-OC(H)O}(CO)4(µ-dppy)2]PF6. Reaction
of [{Ru2[µ-η2-OC(R)O]2(CO)4}n] with dpbipy in n-butanol under reflux likewise afforded products, isolated as
their hexafluorophosphate salts, in which the phosphorus–nitrogen ligands are bridging, viz. [Ru2{µ-η2-OC(R)O}-
(CO)2(µ-dpbipy)2]PF6, the structure of [Ru2{µ-η2-OC(Me)O}(CO)2(µ-dpbipy)2]PF6 being established X-ray
crystallographically.
The carboxylate-bridged polymers [{Ru2[µ-η2-OC(R)O]2-
(CO)4}n] (R = H, Me, Et, Ph, etc.), readily synthesized by a
number of procedures including the reaction of [Ru3(CO)12]
with the appropriate carboxylic acids,1 together with their corre-
sponding solvated products [Ru2{µ-η2-OC(R)O}2(CO)4-
(solv)2], obtained by treatment of the polymer with donor
solvents such as acetonitrile,1 tetrahydrofuran (thf)2 or hot
alcohol,3 have been established to be excellent precursors for the
synthesis of dinuclear carboxylate-bridged derivatives of
ruthenium(). For instance their reaction with an excess of neu-
tral monodentate donor ligand L such as carbon monoxide,
pyridine and tertiary phosphines affords products of the type
[Ru2{µ-η2-OC(R)O}2(CO)4L2].4,5 Further product types are
formed in their reactions with bidentate neutral ligands.3,6–10
Thus, while the reaction of [{Ru2[µ-η2-OC(R)O]2(CO)4}n] with
2 molar equivalents of Ph2PCH2PPh2 (dppm) in alcohol
under ambient conditions affords [Ru2{µ-η2-OC(R)O}2(CO)4-
(dppm-P)2], the corresponding reaction under reflux gives
[Ru2{µ-η2-OC(R)O}(CO)4(µ-dppm)2]ϩ together with smaller
quantities of [Ru2{OC(O)R}2(CO)4(µ-dppm)2], the former
being readily isolated as its hexafluorophosphate salt. On the
other hand reaction of the polymers with strongly chelating
ligands such as Ph2PC2H4PPh2 and 2,2Ј-bipyridine yields prod-
ucts of the type [Ru2{µ-η2-OC(R)O}(µ-CO)2(L᎐L)2]ϩ (L᎐L =
Ph2PC2H4PPh2, 2,2Ј-bipyridine, etc.). Significantly the acetate
ligand in [Ru2{µ-η2-OC(Me)O}(CO)4(µ-dppm)2]ϩ is susceptible
to nucleophilic substitution by halide and tetrahydroborate
ions, the latter in the presence of carbon monoxide, affording
[Ru2(µ-X)X(CO)3(µ-dppm)2] (X = Cl, Br or I) and [Ru2(µ-CO)-
(CO)4(µ-dppm)2] respectively.11,12
(dpquin) and 6-diphenylphosphino-2,2Ј-bipyridine (dpbipy)
have been investigated.
Results and Discussion
Synthetic studies
Reaction of the polymer [{Ru2[µ-η2-OC(R)O]2(CO)4}n] or its
acetonitrile adduct [Ru2{µ-η2-OC(R)O}2(CO)4(MeCN)2] (R =
H, Me or Et) with 2 molar equivalents of the above ligands, i.e.
dppy, dpquin and dpbipy, in ethanol or toluene under reflux for
short periods of time (less than 4 h) was shown to produce, in
moderate to high yields, air-stable, sparingly soluble neutral
compounds characterised as [Ru2{µ-η2-OC(R)O}2(CO)4-
(PPh2RЈ)2] 1 (R = H, Me or Et; RЈ = pyridyl, quinolyl or bipyri-
dyl). All nine compounds were found to exhibit very similar
band patterns in the C᎐O stretching region of their IR spectra,
each pattern comprising four peaks of relative intensity strong,
medium, very strong and weak (shoulder) and with the fre-
quencies of corresponding peaks being very similar. These spec-
tra closely resemble those of the axially substituted compounds
[M2{µ-η2-OC(Me)O}2(CO)4L2] (M = Ru or Os; L = PPh3,
AsPh3, PMe2Ph, PMePh2, C5H5N, MeCN or Ph2PCH2PPh2-P)
in the C᎐O stretching region which is interpreted in terms of the
new compounds adopting a similar core structure with each
ligand functioning as monodentate and co-ordinating
axially.7,8,13 The 31P-{1H} NMR spectra exhibit well resolved
singlets in the range δ 16.9 to 18.1, as expected for a sym-
metrical structure for these compounds. A crystal structure
determination on [Ru2{µ-η2-OC(Me)O}2(CO)4(dppy)2] (see
below) has confirmed the structure proposed. The geometry of
the Ru2{µ-η2-OC(R)O}2(CO)4 core in [Ru2{µ-η2-OC(R)O}2-
(CO)4(L᎐L)2] 1 is the same as that established for the polymer
[{Ru2[µ-η2-OC(R)O]2(CO)4}n].14,15 This reflects that the form-
ation of 1 merely involves the cleavage of the intermolecular
Ru-O(carboxylate)-Ru bridges by the attacking nucleophile.
With the object of synthesizing dinuclear compounds of
ruthenium(), stabilised to fragmentation by phosphorus,
pyridyl and related ligands, the reactions of [{Ru2[µ-η2-
OC(R)O]2(CO)4}n] (R = H, Me or Et) with 2-diphenyl-
phosphinopyridine (dppy), 2-diphenylphosphinoquinoline
J. Chem. Soc., Dalton Trans., 1997, Pages 2843–2848
2843

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Table
1
Selected interatomic distances (Å) and angles (Њ) for
[Ru2{µ-η2-OC(Me)O}2(CO)4(dppy)2]
Ru(1)᎐Ru(2)
Ru(2)᎐P(2)
Ru(2)᎐O(2)
Ru(2)᎐O(4)
Ru(1)᎐C(40)
Ru(2)᎐C(42)
O(2)᎐C(35)
O(4)᎐C(37)
C(37)᎐C(38)
2.720(1)
2.413(2)
2.119(6)
2.071(6)
1.80(1)
1.78(1)
1.22(1)
1.28(1)
1.54(2)
Ru(1)᎐P(1)
Ru(1)᎐O(1)
Ru(1)᎐O(3)
Ru(1)᎐C(39)
Ru(2)᎐C(41)
O(1)᎐C(35)
O(3)᎐C(37)
C(35)᎐C(36)
2.410(2)
2.118(7)
2.054(7)
1.80(1)
1.84(1)
1.27(1)
1.26(1)
1.51(1)
Ru(2)᎐Ru(1)᎐P(1)
Ru(2)᎐Ru(1)᎐O(1)
Ru(2)᎐Ru(1)᎐O(3)
Ru(2)᎐Ru(1)᎐C(39)
Ru(2)᎐Ru(1)᎐C(40)
P(1)᎐Ru(1)᎐O(1)
P(1)᎐Ru(1)᎐O(3)
P(1)᎐Ru(1)᎐C(39)
P(1)᎐Ru(1)᎐C(40)
O(1)᎐Ru(1)᎐O(3)
O(1)᎐Ru(1)᎐C(39)
O(1)᎐Ru(1)᎐C(40)
O(3)᎐Ru(1)᎐C(39)
O(3)᎐Ru(1)᎐C(40)
C(39)᎐Ru(1)᎐C(40)
169.5(1)
83.5(2)
87.4(2)
92.8(3)
89.6(4)
89.9(2)
87.4(2)
94.1(3)
98.6(4)
85.6(3)
175.6(4)
89.5(5)
96.4(5)
172.2(5)
88.1(7)
Ru(1)᎐Ru(2)᎐P(2)
Ru(1)᎐Ru(2)᎐O(2)
Ru(1)᎐Ru(2)᎐O(4)
176.6(1)
82.8(1)
84.4(2)
Ru(1)᎐Ru(2)᎐C(41)
Ru(1)᎐Ru(2)᎐C(42)
P(2)᎐Ru(2)᎐O(2)
P(2)᎐Ru(2)᎐O(4)
P(2)᎐Ru(2)᎐C(41)
P(2)᎐Ru(2)᎐C(42)
O(2)᎐Ru(2)᎐O(4)
O(2)᎐Ru(2)᎐C(41)
O(2)᎐Ru(2)᎐C(42)
O(4)᎐Ru(2)᎐C(41)
O(4)᎐Ru(2)᎐C(42)
C(41)᎐Ru(2)᎐C(42)
93.0(3)
88.4(3)
93.8(2)
95.5(2)
90.4(3)
91.5(3)
84.1(3)
174.5(3)
91.4(3)
92.0(4)
171.9(3)
91.9(4)
One of the carboxylate ligands in [{Ru2[µ-η2-OC(R)O]2-
(CO)4}n] (R = H, Me or Et) is readily displaced if the reaction of
this polymer with 2 molar equivalents of dppy or dpquin is
carried out in toluene under reflux in the presence of NH4PF6
and carbon monoxide is passed through the solution. The reac-
tion is relatively slow and reaction times of between 4 and 8 h
are required. The products which separate from solution were
characterised as the cationic species [Ru2{µ-η2-OC(R)O}(CO)4-
(µ-dppy)2]PF6 2 or [Ru2{µ-η2-OC(R)O}(CO)4(µ-dpquin)2]PF6 3
in which the phosphorus–nitrogen ligands adopt a bridging co-
ordination mode. Four peaks of distinctive band pattern were
observed in the C᎐O stretching region of the IR spectra of
these compounds, this band pattern being very similar to that
observed in the spectra of the analogous dppm- and dmpm-
bridged compounds [Ru2{µ-η2-OC(R)O}(CO)4(µ-dppm)2]PF6
and [Ru2{µ-η2-OC(R)O}(CO)4(µ-dmpm)2]PF6 (dmpm = Me2-
PCH2PMe2).3 The 31P-{1H} NMR spectra of these compounds
exhibit well resolved singlets, well down field of compounds of
type 1, consistent again with products of symmetrical structure.
A crystal structure determination on [Ru2{µ-η2-OC(H)O}-
(CO)4(µ-dppy)2]PF6 has confirmed the structural features being
proposed for 2 on the basis of the spectroscopic evidence.
Compounds of type 2 or 3 can also be synthesized directly
from the corresponding compound of type 1, simply by reflux-
ing a suspension of the latter in toluene in the presence of
NH4PF6 and under a very slight pressure of carbon monoxide.
This is interpreted in terms of 1 being an intermediate in the
formation of 2 or 3. This conversion involves the migration
of the pendant phosphorus–nitrogen ligands from axial to
equatorial positions together with the displacement of a carb-
oxylate ion on co-ordination of these ligands to the two
rutheniums through their nitrogen atoms.
The phosphorus bipyridyl ligand dpbipy also affords prod-
ucts in which the ligand functions in a bridging co-ordination
mode, on reaction with the polymer [{Ru2[µ-η2-OC(R)O]2-
(CO)4}n] but fairly vigorous reaction conditions are required.
Thus reaction of the polymer with 2 molar equivalents of the
ligand in n-butanol under reflux for at least 3 h and subsequent
addition of an excess of NH4PF6 led to the separation of a
brown product from solution which after crystallisation from
acetone–diethyl ether (1:1) was characterised as [Ru2{µ-η2-
OC(R)O}(CO)2(µ-dpbipy)2]PF6 4. The IR spectra of these
compounds contain two peaks in the C᎐O stretching region,
one of which occurs as a shoulder on the other, while their 31P-
{1H} NMR spectra each exhibit a singlet, again well downfield
of those observed for the monodentate derivatives and, at the
same time, slightly more downfield than those for [Ru2{µ-η2-
OC(R)O}(CO)4(µ-dppy)2]PF6 and [Ru2{µ-η2-OC(R)O}(CO)4-
(µ-dpquin)2]PF6. The structure of these compounds has been
established unequivocally through a crystal structure determin-
ation of [Ru2{µ-η2-OC(Me)O}(CO)2(µ-dpbipy)2]PF6.
Crystal structure determinations
[Ru2{ì-ç2-OC(Me)O}2(CO)4(dppy)2]. The stereochemistry of
this compound is illustrated in Fig. 1 and a selection of inter-
atomic distances and angles given in Table 1. The two
ruthenium atoms, separated by a distance of 2.720(1) Å corre-
sponding to a formal ruthenium–ruthenium bond, are linked
through two bridging acetate ligands cis disposed with respect
to each other. Two carbonyl groups on each ruthenium atom
are co-ordinated mutually cis and trans to the two bridging
acetates while the two phosphorus pyridyl ligands which func-
tion as monodentate occupy axial sites on each ruthenium. The
complex adopts an essentially eclipsed configuration as
reflected by C(39)᎐Ru(1)᎐Ru(2)᎐C(41) and C(40)᎐Ru(1)᎐Ru(2)᎐
C(42) torsion angles of 8.5 and 4.6Њ respectively. The structure
is similar to those reported for the carboxylate-bridged com-
pounds [Ru2{µ-η2-OC(R)O}2(CO)4L2] (R = Me, Prn, Ph or 4-
FC6H4; L = CO, PBut3, py, H2O or PhCO2H)15–18 and for the
anionic ligand-bridged derivatives [Ru2(µ-X)2(CO)4(PR3)2]
(X = 3,5-dimethylpyrazolato or pyridin-2-onato; R = But, Ph or
p-MeC6H4).13,19,20
[Ru2{ì-ç2-OC(H)O}(CO)4(ì-dppy)2]PF6. A perspective view
of the cation of this complex is illustrated in Fig. 2 and a selec-
tion of interatomic distances and angles given in Table 2. The
two ruthenium atoms are bridged by two mutually trans dppy
ligands as well as by a formate anion. Each ruthenium is also
bound to two carbonyl groups, cis disposed with respect to each
other, with one occupying an equatorial site and the other co-
ordinating axially. The local geometry of each ruthenium is
essentially octahedral, the sixth site being occupied by the other
ruthenium atom, with the angles subtended by cis-disposed
ligands ranging from 80.8(1) to 98.1(2)Њ. The ruthenium–
ruthenium distance of 2.731(1) Å corresponds to a formal
ruthenium–ruthenium bond. The cation is substantially dis-
torted from an eclipsed configuration as reflected by the
P(1)᎐Ru(1)᎐Ru(2)᎐N(1) and P(2)᎐Ru(2)᎐Ru(1)᎐N(2) torsion
angles of 28.2 and 30.7Њ respectively. This torsional twist about
the ruthenium–ruthenium vector is markedly larger than that
2844
J. Chem. Soc., Dalton Trans., 1997, Pages 2843–2848

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Fig. 1 Molecular structure of [Ru2{µ-η2-OC(Me)O}2(CO)4(dppy)2] showing the atom labelling scheme
Table
2
Selected interatomic distances (Å) and angles (Њ) for
[Ru2{µ-η2-OC(H)O}(CO)4(µ-dppy)2]PF6
Ru(1)᎐Ru(2)
Ru(1)᎐O(3)
Ru(1)᎐C(35)
Ru(2)᎐P(2)
Ru(2)᎐N(1)
Ru(2)᎐C(38)
2.731(1)
2.132(3)
1.960(5)
2.296(1)
2.178(4)
1.841(5)
Ru(1)᎐P(1)
Ru(1)᎐N(2)
Ru(1)᎐C(36)
Ru(2)᎐O(6)
Ru(2)᎐C(37)
2.287(1)
2.178(4)
1.848(5)
2.151(3)
1.943(5)
Ru(2)᎐Ru(1)᎐P(1)
Ru(2)᎐Ru(1)᎐O(3)
Ru(2)᎐Ru(1)᎐N(2)
Ru(2)᎐Ru(1)᎐C(35)
Ru(2)᎐Ru(1)᎐C(36)
P(1)᎐Ru(1)᎐O(3)
P(1)᎐Ru(1)᎐N(2)
P(1)᎐Ru(1)᎐C(35)
P(1)᎐Ru(1)᎐C(36)
O(3)᎐Ru(1)᎐N(2)
O(3)᎐Ru(1)᎐C(35)
O(3)᎐Ru(1)᎐C(36)
N(2)᎐Ru(1)᎐C(35)
N(2)᎐Ru(1)᎐C(36)
C(35)᎐Ru(1)᎐C(36)
84.8(1)
82.3(1)
88.8(1)
176.2(2)
91.2(1)
88.6(1)
168.3(1)
92.8(2)
91.8(2)
80.8(1)
94.8(2)
173.5(2)
93.1(2)
98.1(2)
91.7(2)
Ru(1)᎐Ru(2)᎐P(2)
Ru(1)᎐Ru(2)᎐O(6)
Ru(1)᎐Ru(2)᎐N(1)
Ru(1)᎐Ru(2)᎐C(37)
Ru(1)᎐Ru(2)᎐C(38)
P(2)᎐Ru(2)᎐O(6)
P(2)᎐Ru(2)᎐N(1)
P(2)᎐Ru(2)᎐C(37)
P(2)᎐Ru(2)᎐C(38)
O(6)᎐Ru(2)᎐N(1)
O(6)᎐Ru(2)᎐C(37)
O(6)᎐Ru(2)᎐C(38)
N(1)᎐Ru(2)᎐C(37)
N(1)᎐Ru(2)᎐C(38)
C(37)᎐Ru(2)᎐C(38)
83.5(1)
81.5(1)
89.3(1)
173.5(2)
93.5(1)
90.7(1)
170.1(1)
91.8(2)
93.0(2)
81.5(1)
94.3(3)
173.4(1)
94.9(2)
94.2(2)
91.0(2)
observed in [Ru2{µ-η2-OC(Me)O}(CO)4{µ-(PriO)2PN(Et)-
P(OPri)2}2]PF6, with corresponding torsion angles of 17.3
Fig.
2
Structure of the cation in [Ru2{µ-η2-OC(H)O}(CO)4-
(µ-dppy)2]PF6 showing the atom labelling scheme
3
and 13.8Њ,21 [Ru2{µ-η2-OC(Me)O}(CO)4(µ-dppm)2]PF6 and
[Ru2{µ-η2-OC(Ph)O}(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2]PF6,
the latter adopting in fact an almost eclipsed configuration as
reflected by the corresponding torsion angles of 0.7 and 1.5Њ
respectively.22 Significantly, the ruthenium–carbon distances
for the axial carbonyls [Ru(1)᎐C(35) 1.960(5), Ru(2)᎐C(37)
1.943(5) Å] are substantially longer than those for the
equatorial carbonyls [Ru(1)᎐C(36) 1.848(5), Ru(2)᎐C(38)
1.841(5) Å], which undoubtedly reflects large differences in the
trans influence of the formate ion and the adjacent ruthenium
atom.
ruthenium with these two carbonyl groups being situated at
equatorial sites trans to the acetate group. The ruthenium–
ruthenium distance of 2.688(2) Å, which again corresponds to a
formal ruthenium–ruthenium single bond, is one of the short-
est known for compounds of this type. The cation adopts a
partially staggered conformation as reflected by the P(1)᎐Ru᎐
RuЈ᎐N(1) torsion angle of 22.6Њ. Both ruthenium atoms have a
distorted octahedral geometry with angles subtended by cis-
disposed ligands ranging from 76.1(2) [N(1Ј)᎐Ru᎐N(2Ј)] to
106.5(7)Њ [P(1)᎐Ru᎐N(2Ј)]. This distortion is undoubtedly as a
consequence of the restrictive bite of the dpbipy ligands and in
particular that of the bipyridyl fragments with this restriction in
turn being reflected by the angle associated with the group co-
ordinated at the axial site of 164.3(8)Њ [RuЈ᎐Ru᎐N(2Ј)] and the
dihedral angle between the pyridyl rings of the dipyridyl frag-
ment of 11.2Њ.
[Ru2{ì-ç2-OC(Me)O}(CO)4(ì-dpbipy)2]PF6. The structure
of the cation of this complex is illustrated in Fig. 3 and a selec-
tion of interatomic distances and angles given in Table 3. The
two ruthenium atoms are bridged by two mutually trans dpbipy
ligands as well as by an acetate group with the two dpbipy
ligands functioning as tridentates. A carbonyl group and the
other ruthenium atom complete the octahedron around each
J. Chem. Soc., Dalton Trans., 1997, Pages 2843–2848
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Fig. 3 Structure of the cation in [Ru2{µ-η2-OC(Me)O}(CO)2(µ-dpbipy)2]PF6 showing the atom labelling scheme
substantial precipitation had been effected. Although all
products were isolated sufficiently pure not to require further
crystallisation, highly crystalline material could be isolated
from a slowly evaporating CH2Cl2–ethanol (1:1 v/v) solution
of the product. Yields: R = H, 60; Me, 75; Et, 75% (Found:
C, 51.2; H, 3.7; N, 2.9. Calc. for C40H30N2O8P2Ru2: C, 51.6;
H, 3.3; N, 3.0. Found: C, 52.7; H, 4.1; N, 2.6. Calc. for
C42H34N2O8P2Ru2: C, 52.6; H, 3.6; N, 2.9. Found: C, 53.4; H,
4.2; N, 2.6. Calc. for C44H38N2O8P2Ru2: C, 53.6; H, 3.9; N,
2.8%).
Table
3
Selected interatomic distances (Å) and angles (Њ) for
[Ru2{µ-η2-OC(Me)O}(CO)2(µ-dpbipy)2]PF6
Ru᎐RuЈ
2.688(2)
2.170(11)
2.198(3)
1.25(1)
Ru᎐P(1)
2.250(4)
2.120(2)
1.78(2)
1.51(3)
Ru᎐O(2)
Ru᎐N(2Ј)
O(2)᎐C(24)
Ru᎐N(1Ј)
Ru᎐C(23)
C(24)᎐C(25)
RuЈ᎐Ru᎐P(1)
83.1(3)
92.7(2)
95.5(8)
171.6(4)
92.3(6)
84.4(3)
76.1(2)
95.3(6)
RuЈ᎐Ru᎐O(2)
RuЈ᎐Ru᎐N(2Ј)
P(1)᎐Ru᎐O(2)
P(1)᎐Ru᎐N(2Ј)
O(2)᎐Ru᎐N(1Ј)
O(2)᎐Ru᎐C(23)
N(2Ј)᎐Ru᎐C(23)
83.3(6)
164.3(8)
89.2(3)
106.5(7)
83.1(4)
177.8(6)
96.5(2)
RuЈ᎐Ru᎐N(1Ј)
RuЈ᎐Ru᎐C(23)
P(1)᎐Ru᎐N(1Ј)
P(1)᎐Ru᎐C(23)
O(2)᎐Ru᎐N(2Ј)
N(2Ј)᎐Ru᎐N(1Ј)
N(1Ј)᎐Ru᎐C(23)
[Ru2{ì-ç2-OC(R)O}2(CO)4(dpquin)2] (R ؍ H, Me or Et). A
suspension of the appropriate carboxylate-bridged polymer
[{Ru2[µ-η2-OC(R)O]2(CO)4}n] (R = H, Me or Et) (0.75 mmol)
and dpquin (0.47 g, 1.5 mmol) in toluene (10 cm3) was refluxed
whilst gently passing CO through the solution for 3 h. The
suspension gradually dissolved, yielding a bright yellow solu-
tion from which the product precipitated. This yellow product
was filtered off, washed with diethyl ether (2 × 5 cm3) and dried
in vacuo for 2 h. The products were sufficiently pure in all cases
so as not to require further crystallisation. Yields: R = H, 80;
Me, 90; Et, 70% (Found: C, 55.6; H, 3.5; N, 2.5. Calc. for
C48H34N2O8P2Ru2: C, 55.9; H, 3.3; N, 2.7. Found: C, 57.1; H,
3.5; N, 2.8. Calc. for C50H38N2O8P2Ru2: C, 56.7; H, 3.6; N, 2.7.
Found: C, 57.2; H, 3.7; N, 2.5. Calc. for C52H42N2O8P2Ru2: C,
57.5; H, 3.9; N, 2.6%).
Experimental
The ligands dppy, dpquin and dpbipy were synthesized accord-
ing to procedures described previously23–25 while [{Ru2[µ-η2-
OC(R)O]2(CO)4}n] (R = H, Me or Et) were also synthesized
according to a literature method.1 All reactions and manipu-
lations were carried out under an atmosphere of nitrogen
using Schlenk techniques. Solvents were purified according to
recognised procedures. Infrared spectra were measured on a
Shimadzu FTIR-4300 spectrometer, 31P-{1H} NMR spectra on
1
a Varian FT80A instrument and H NMR spectra on a Varian
Gemini 200 spectrometer. Relevant spectroscopic data are
summarised in Table 4.
[Ru2{ì-ç2-OC(R)O}2(CO)4(dpbipy)2] (R ؍ H, Me or Et). A
suspension of the appropriate carboxylate-bridged polymer
[{Ru2[µ-η2-OC(R)O]2(CO)4}n] (R = H, Me or Et) (0.3 mmol)
and dpbipy (0.21 g, 0.6 mmol) in n-butanol (15 cm3) was
refluxed for 3 h. The suspension gradually dissolved affording
a clear brown-orange solution at the end of the reaction. The
hot solution was filtered quickly and then carefully reduced in
volume to ca. 5 cm3 under reduced pressure, yielding the prod-
uct as a dark orange microcrystalline material. This was filtered
off, washed with cold (0 ЊC) butan-1-ol (2 cm3) and diethyl ether
(10 cm3) and dried in vacuo for 12 h at 40 ЊC effectively to
remove any residual n-butanol. The product was recrystallised
from a slowly evaporating saturated acetone–ethanol (1:1 v/v)
solution. Yields: R = H, 60; Me, 70; Et, 70% (Found: C, 55.8; H,
3.5; N, 5.4. Calc. for C50H36N4O8P2Ru2: C, 55.4; H, 3.3; N, 5.2.
Syntheses
[Ru2{ì-ç2-OC(R)O}2(CO)4(dppy)2] (R ؍ H, Me or Et). A sus-
pension of the appropriate carboxylate-bridged polymer
[{Ru2[µ-η2-OC(R)O]2(CO)4}n] (R = H, Me or Et) (0.75 mmol)
and dppy (0.40 g, 1.5 mmol) in absolute ethanol (15 cm3) was
refluxed for 45 min. The suspension gradually dissolved to be
replaced by a yellow-orange precipitate which was filtered off,
washed with cold (0 ЊC) absolute ethanol (5 cm3) and diethyl
ether (5 cm3) and dried in vacuo for 1 h. In cases where the
product had not precipitated after 45 min (for R = H), the
solvent was carefully removed under reduced pressure until
2846
J. Chem. Soc., Dalton Trans., 1997, Pages 2843–2848

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Table 4 Infrared and 31P-{1H} NMR spectroscopic data
Compound
ν (CO)a/cmϪ1
ν (CO2)a/cmϪ1
31P-{1H} NMR b
[Ru2{µ-η2-OC(H)O}2(CO)4(dppy)2]
2025s, 1981m, 1952vs, 1914w (sh)
2027s, 1981m, 1953vs, 1913w (sh)
2027s, 1977m, 1952vs, 1912w (sh)
2033s, 1978m, 1945vs, 1913w (sh)
2032s, 1978m, 1950vs, 1913w (sh)
2034s, 1978m, 1950vs, 1912w (sh)
2026s, 1989m, 1952vs, 1912w (sh)
2025s, 1989m, 1953vs, 1914w (sh)
2025s, 1981m, 1952vs, 1913w (sh)
2021m, 1995vs, 1964s, 1942w
2027m, 2004vs, 1969s, 1950w
2023m, 1999vs, 1968s, 1951w
2060m, 1986vs, 1947s, 1920w
2056m, 1992vs, 1953s, 1920w
2061m, 1982vs, 1951s, 1926w
1934vs, 1899m (sh)
1572s
1571s
1574s
1567s
1568s
1570s
1575s
1572s
1566s
1557w
1541m
1550m
1556w
1553w
1552m
1557m
1551m
1576m
16.91 (s)
16.88 (s)
17.02 (s)
18.09 (s)
17.50 (s)
17.53 (s)
17.62 (s)c
17.79 (s)c
17.80 (s)c
45.03 (s)
45.24 (s)
45.91 (s)
47.22 (s)
47.34 (s)
47.31 (s)
45.03 (s)
45.24 (s)
45.91 (s)
[Ru2{µ-η2-OC(Me)O}2(CO)4(dppy)2]
[Ru2{µ-η2-OC(Et)O}2(CO)4(dppy)2]
[Ru2{µ-η2-OC(H)O}2(CO)4(dpquin)2]
[Ru2{µ-η2-OC(Me)O}2(CO)4(dpquin)2]
[Ru2{µ-η2-OC(Et)O}2(CO)4(dpquin)2]
[Ru2{µ-η2-OC(H)O}2(CO)4(dpbipy)2]
[Ru2{µ-η2-OC(Me)O}2(CO)4(dpbipy)2]
[Ru2{µ-η2-OC(Et)O}2(CO)4(dpbipy)2]
[Ru2{µ-η2-OC(H)O}(CO)4(µ-dppy)2]PF6
[Ru2{µ-η2-OC(Me)O}(CO)4(µ-dppy)2]PF6
[Ru2{µ-η2-OC(Et)O}(CO)4(µ-dppy)2]PF6
[Ru2{µ-η2-OC(H)O}(CO)4(µ-dpquin)2] PF6
[Ru2{µ-η2-OC(Me)O}(CO)4(µ-dpquin)2]PF6
[Ru2{µ-η2-OC(Et)O}(CO)4(µ-dpquin)2]PF6
[Ru2{µ-η2-OC(H)O}(CO)2(µ-dpbipy)2]PF6
[Ru2{µ-η2-OC(Me)O}(CO)2(µ-dpbipy)2]PF6
[Ru2{µ-η2-OC(Et)O}(CO)2(µ-dpbipy)2] PF6
1930vs, 1890m (sh)
1942vs, 1903m (sh)
a
Recorded in CH2Cl2. Abbreviations: v = very, s = strong, m = medium, w = weak, sh = shoulder. b δ in ppm relative to H3PO4. Recorded in CD2Cl2
unless otherwise specified. Abbreviation: s = singlet. c Recorded in [2H6]acetone.
Table 5 Crystallographic data
[Ru2{µ-η2-OC(Me)O}2(CO)4-
(dppy)2]
[Ru2{µ-η2-OC(H)O}(CO)4-
(µ-dppy)2]PF6
[Ru2{µ-η2-OC(Me)O}(CO)2-
(µ-dpbipy)2]PF6
Formula
M
Crystal system
Space group
a/Å
b/Å
c/Å
α/Њ
C42H34N2O8P2Ru2
958.83
C39H29F6N2O6P3Ru2
C48H37F6N4O4P3Ru2
1142.90
Monoclinic
P2/a (no. 13)
14.743(4)
9.985(3)
17.249(6)
—
91.34
—
2538(1)
2
1.495
1030.72
Monoclinic
P21/n (no. 14)
12.979(4)
16.224(5)
19.922(5)
—
108.93(2)
—
3968(1)
4
Triclinic
¯
P1 (no. 2)
9.484(2)
13.146(3)
16.838(6)
82.10(2)
87.85(2)
77.62(2)
2031(2)
2
β/Њ
γ/Њ
U/Å3
Z
Dc/g cmϪ3
1.568
1.725
F(000)
964
8.64
2048
9.11
1128
7.47
µ/cmϪ1
Crystal size/mm
Measured reflections
Independent reflections
Observed reflections [I > 3σ(I)]
No. variables
Weights (g)
0.40 × 0.32 × 0.30
5872
5230
4582
512
0.63 × 0.20 × 0.10
5927
4887
4067
524
0.42 × 0.19 × 0.33
5655
3231
2198
305
0.0010
0.070
0.0007
0.031
0.014
0.077
R
RЈ
0.086
0.033
0.084
∆/σ (maximum)
0.150
1.10
0.014
0.43
0.152
0.95
∆ρ/e ÅϪ3
¹
¹
Weighting scheme: w = 1/[σ2(F) ϩ gF2]. R = Σ(|Fo| Ϫ |Fc|)/Σ|Fo|, RЈ = Σw²(|Fo| Ϫ |Fc|)/Σw²Fo.
Found: C, 55.9; H, 3.7; N, 4.7. Calc. for C52H40N4O8P2Ru2: C,
56.1; H, 3.6; N, 5.0. Found: C, 56.7; H, 3.6; N, 4.6. Calc. for
C54H44N4O8P2Ru2: C, 56.8; H, 3.9; N, 4.9%).
yellow crystalline material, isolated as described above. Yields:
R = H, 65; Me, 70; Et, 65% (Found: C, 45.9; H, 2.9; N, 2.7.
Calc. for C39H29F6N2O6P3Ru2: C, 45.5; H, 2.8; N, 2.7. Found: C,
45.7; H, 3.2; N, 2.8. Calc. for C40H31F6N2O6P3Ru2: C, 46.0; H,
3.0; N, 2.7. Found: C, 46.3; H, 3.4; N, 2.8. Calc. for C41H33F6-
N2O6P3Ru2: C, 46.5; H, 3.1; N, 2.7%).
[Ru2{ì-ç2-OC(R)O}(CO)4(ì-dppy)2]PF6 (R ؍ H, Me or Et).
A suspension of the appropriate carboxylate-bridged polymer
[{Ru2[µ-η2-OC(R)O]2(CO)4}n] (R = H, Me or Et) (0.23 mmol),
dppy (0.125 g, 0.46 mmol) and NH4PF6 (0.075 g, 0.46 mmol) in
toluene (15 cm3) was refluxed whilst gently passing CO through
the solution for 4 h (for R = H and Me) or 6 h (for R = Et).
During this time the solution first turned orange and then
yellow with separation of a bright yellow precipitate. The reac-
tion mixture was cooled to room temperature and the solid
filtered off, washed with diethyl ether (2 × 5 cm3) and dried in
vacuo. Further product was obtained by reducing the volume of
the filtrate to ca. 3 cm3 and keeping it at Ϫ25 ЊC for 12 h. The
combined products were crystallised from a slowly evaporating
saturated CH2Cl2–ethanol (1:1 v/v) solution to afford a bright
[Ru2{ì-ç2-OC(R)O}(CO)4(ì-dpquin)2]PF6 (R ؍ H, Me or
Et). A suspension of the appropriate carboxylate-bridged
polymer [{Ru2[µ-η2-OC(R)O]2(CO)4}n] (0.23 mmol), dpquin
(0.145 g, 0.46 mmol) and an excess of NH4PF6 (0.30 g, 1.84
mmol) in toluene (15 cm3) was refluxed whilst gently passing
CO through the solution for 8 h. During this time the suspen-
sion slowly dissolved yielding a yellow solution from which a
yellow product precipitated. The solution was cooled and the
product filtered off. It was washed with diethyl ether (2 × 5 cm3)
and dried in vacuo. Further product could not be isolated from
the mother-liquor, removal of the solvent under reduced pres-
J. Chem. Soc., Dalton Trans., 1997, Pages 2843–2848
2847

View Article Online
sure yielding the corresponding compounds containing pen-
dant dpquin ligands. Yields: R = H, 10; Me, 15; Et, 5% (Found:
C, 49.9; H, 2.8; N, 2.5. Calc. for C47H33F6N2O6P3Ru2: C, 49.9;
H, 2.9; N, 2.5. Found: C, 50.5; H, 3.6; N, 2.5. Calc. for
C48H35F6N2O6P3Ru2: C, 50.4; H, 3.1; N, 2.5. Found: C, 50.5; H,
3.3; N, 2.6. Calc. for C49H37F6N2O6P3Ru2: C, 50.8; H, 3.2; N,
2.4%).
References
1 G. R. Crooks, B. F. G. Johnson, J. Lewis, I. G. Williams and
G. Gamlen, J. Chem. Soc. A, 1969, 2761.
2 D. S. Bohle and H. Vahrenkamp, Inorg. Chem., 1990, 29, 1097.
3 S. J. Sherlock, M. Cowie, E. Singleton and M. M. de V. Steyn,
Organometallics, 1988, 7, 1663.
4 M. Bianchi, U. Matteoli, P. Ferdiani, F. Piacenti, M. Nardeli and
G. Pelizzi, Chem. Ind. (Milan), 1981, 63, 475.
5 M. Bianchi, P. Ferdiani, U. Matteoli, G. Menchi, F. Piacenti and
G. Pettrucci, J. Organomet. Chem., 1983, 259, 207.
6 M. M. de V. Steyn and E. Singleton, Acta Crystallogr., Sect. C, 1988,
44, 1722.
7 E. Singleton, P. H. van Rooyen and M. M. de V. Steyn, S. Afr. J.
Chem., 1989, 42, 577.
8 R. W. Hilts, S. J. Sherlock, M. Cowie, E. Singleton and M. M.
de V. Steyn, Inorg. Chem., 1990, 29, 3161.
9 G. F. Schmidt and G. Süss-Fink, J. Organomet. Chem., 1989, 362,
179.
10 P. Frediani, M. Bianchi, A. Salvini, R. Guarducci, L. Carluccio and
F. Piacenti, J. Organomet. Chem., 1993, 463, 187.
11 K.-B. Shiu, W.-N. Guo, T.-J. Chan, J.-C. Wang, L.-S. Liou,
S.-M. Peng and M.-C. Cheng, Organometallics, 1995, 14, 1732.
12 A. P. Steyn, unpublished work.
13 R. Mason, K. M. Thomas, D. F. Gill and B. L. Shaw, J. Organomet.
Chem., 1972, 40, C67.
14 M. Rotem, Y. Shvo, I. Goldberg and U. Shmueli, Organometallics,
1984, 3, 1758.
15 M. Rotem, I. Goldberg, U. Shmueli and Y. Shvo, J. Organomet.
Chem., 1986, 314, 185.
16 J. G. Bullitt and F. A. Cotton, Inorg. Chim. Acta, 1971, 5, 406.
17 M. Spohn, T. Vogt and J. Stahle, Z. Naturforsch., Teil B, 1986, 41,
1373.
18 H. Schumann, J. Opitz and J. Pickardt, J. Organomet. Chem., 1977,
128, 253.
19 J. A. Cabeza, C. Landazuri, L. A. Oro, A. Tiripicchio and
M. Tiripicchio-Camellini, J. Organomet. Chem., 1987, 322, C16.
20 S. J. Sherlock, M. Cowie, E. Singleton and M. M. de V. Steyn,
J. Organomet. Chem., 1989, 361, 353.
21 J. S. Field, R. J. Haines, J. Sundermeyer and S. F. Woollam, J. Chem.
Soc., Dalton Trans., 1993, 2735.
22 J. S. Field, R. J. Haines, J. Sundermeyer, A. Wood and
S. F. Woollam, Polyhedron, 1994, 12, 2425.
23 G. Newkome and D. Hager, J. Org. Chem., 1978, 43, 947.
24 W. K. Schauerte, M.Sc. Thesis, University of Natal, Pietermaritz-
burg, 1992.
25 J. S. Field, R. J. Haines, C. J. Parry and S. H. Sookraj, S. Afr. J.
Chem., 1993, 46, 70.
[Ru2{ì-ç2-OC(R)O}(CO)2(ì-dpbipy)2]PF6 (R ؍ H, Me or
Et). A suspension of the appropriate carboxylate-bridged
polymer [{Ru2[µ-η2-OC(R)O]2(CO)4}n] (0.3 mmol) and dpbipy
(0.205 g, 0.6 mmol) in n-butanol (10 cm3) was refluxed at 120 ЊC
for 24 h. The solution slowly changed from orange-yellow
through to dark brown. The reaction solution was cooled to
room temperature and filtered. A hot solution of NH4PF6
(0.105 g, 0.65 mmol) in butan-1-ol was added dropwise with
stirring to precipitate the product as a brown powder. This was
filtered off, washed with diethyl ether (5 × 5 cm3) and dried in
vacuo for 12 h at 40 ЊC effectively to remove any residual
n-butanol. Recrystallisation of the product from acetonitrile–
diethyl ether (1:1 v/v) at Ϫ25 ЊC afforded the analytically pure
product as dark brown needles. Yields: R = H, 70; Me, 80; Et,
65% (Found: C, 49.9; H, 3.0; N, 4.7. Calc. for C47H35F6N4-
O4P3Ru2: C, 50.0; H, 3.1; N, 5.0. Found: C, 50.0; H, 3.7; N, 4.7.
Calc. for C48H37F6N4O4P3Ru2: C, 50.4; H, 3.3; N, 4.9. Found: C,
50.4; H, 3.1; N, 4.7. Calc. for C49H39F6N4O4P3Ru2: C, 50.9; H,
3.4; N, 4.8%).
Crystallography
Crystal data for [Ru2{µ-η2-OC(Me)O}2(CO)4(dppy)2], [Ru2-
{µ-η2-OC(H)O}(CO)4(µ-dppy)2]PF6,
and
[Ru2{µ-η2-OC-
(Me)O}(CO)2(µ-dpbipy)2]PF6 as well as details of the structure
solution and refinement are summarised in Table 5.
Intensity data were collected at 295 K on a CAD4 diffract-
ometer by the variable-speed ω–2θ scan method in the range
3 р 2θ р 46Њ with Mo-Kα radiation (λ = 0.710 69 Å) the data
being corrected for absorption by the ψ-scan method.26 The
structures were solved by standard Patterson methods and sub-
sequently completed by Fourier recycling and full-matrix least-
squares refinement based on F.27 Non-hydrogen atoms were
assigned anisotropic thermal factors and the hydrogen atoms a
single common thermal factor; the latter were placed in calcu-
lated positions. Neutral atom scattering factors were used with
corrections for anomalous dispersion.28
26 A. C. T. North, D. C. Philips and F. A. Mathews, Acta Crystallogr.,
Sect. A, 1968, 24, 35.
27 G. M. Sheldrick, SHELX 76, Program for Crystal Structure Solu-
tion and Refinement, University of Cambridge, 1976.
28 International Tables for X-Ray Crystallography, Kynoch Press,
Birmingham, 1974, vol. 4, pp. 99, 148.
CCDC reference number 186/571.
Acknowledgements
The authors express their sincere gratitude to the Foundation
for Research Development and the University of Natal for
financial support.
Received 18th March 1997; Paper 7/01897E
2848
J. Chem. Soc., Dalton Trans., 1997, Pages 2843–2848