Carbonyl-Carboxylato-Ruthenium Complexes Incorporating Diimine Ligands and Unexpected Cyclometalation of Carboxylate Ligands

Article abstract of DOI:10.1021/ic0348401

We report two new synthetic routes to the dinuclear Ru(I) complexes, [Ru^I₂(RCO₂)(CO)₄(N/N) ₂]⁺ (N/N = 2,2′-bipyridine or 1,10-phenanthroline derivatives) that use RuCl₃·3H₂O as a starting material. Direct addition of the bidentate diimine ligand to a methanolic solution of [Ru(CO)₂Cl₂]n and sodium acetate yielded a mixture of [Ru^I₂(MeCO₂)(CO) ₄(N^N)₂]⁺ (N^N = 4,4′-dmbpy, and 5,6-dmphen), and [Ru^II(MeCO₂)₂(CO) ₂(N^N)] (N^N = 4,4′-dmbpy and 5,5′-dmbpy). Single-crystal X-ray studies confirmed that the Ru(II) complexes had a trans-acetate-cis-carbonyl arrangement of the ligands. In contrast, the use of sodium benzoate resulted in the unexpected formation of a Ru-C bond producing ortho-cyclometalated complexes, [Ru^II(O₂CC ₆H₄)(CO)₂(N^N)], where N^N = bpy or phen. A second approach used ligand exchange between a bidentate ligand (N^N) and the pyridine ligands of [Ru^I(RCO₂)(CO)₂(py)] ₂ to convert these neutral complexes into [Ru^I ₂(RCO₂)(CO)₄(N^N)₂]⁺. This method, although it involved more steps, was applicable for a wider variety of diimine ligands (R = Me and N^N = 4,4′-dmbpy, 5,5′-dmbpy, 5,6-dmphen; R = Ph and N^N = bpy, phen, 5,6-dmphen).

Full text of DOI:10.1021/ic0348401

Inorg. Chem. 2004, 43, 683−691
Carbonyl−Carboxylato−Ruthenium Complexes Incorporating Diimine
Ligands and Unexpected Cyclometalation of Carboxylate Ligands
,†
Pauline Pearson,† Christopher M. Kepert,† Glen B. Deacon,† Leone Spiccia,* Andrew C. Warden,†
Brian W. Skelton,‡ and Allan H. White‡
School of Chemistry, Monash UniVersity, 3800, Victoria, Australia, and Chemistry,
UniVersity of Western Australia, Crawley, 6009, WA, Australia
Received July 17, 2003
I
We report two new synthetic routes to the dinuclear Ru(I) complexes, [Ru2(RCO )(CO)4(N∧N)2]+ (N∧N ) 2,2′-
2
bipyridine or 1,10-phenanthroline derivatives) that use RuCl3‚3H O as a starting material. Direct addition of the
2
bidentate diimine ligand to a methanolic solution of [Ru(CO)2Cl2]n and sodium acetate yielded a mixture of
I
II
[Ru2(MeCO )(CO)4(N∧N)2]+ (N∧N ) 4,4′-dmbpy, and 5,6-dmphen), and [Ru (MeCO ) (CO)2(N∧N)] (N∧N ) 4,4′-
2
2 2
dmbpy and 5,5′-dmbpy). Single-crystal X-ray studies confirmed that the Ru(II) complexes had a trans-acetate−
cis-carbonyl arrangement of the ligands. In contrast, the use of sodium benzoate resulted in the unexpected formation
II
of a Ru−C bond producing ortho-cyclometalated complexes, [Ru (O CC H )(CO)2(N∧N)], where N∧N ) bpy or
2
6 4
phen. A second approach used ligand exchange between a bidentate ligand (N∧N) and the pyridine ligands of
I
I
[Ru(RCO )(CO)2(py)]2 to convert these neutral complexes into [Ru2(RCO )(CO)4(N∧N)2]+. This method, although it
2
2
involved more steps, was applicable for a wider variety of diimine ligands (R ) Me and N∧N ) 4,4′-dmbpy,
5,5′-dmbpy, 5,6-dmphen; R ) Ph and N∧N ) bpy, phen, 5,6-dmphen).
Introduction
Carbonyl-carboxylato complexes of ruthenium(I) and (II),
Figure 1, have been of interest due to their favorable catalytic
properties, with respect to, for example, hydrogenation and
carbonylation of organic substrates.1,2 Unfortunately the high
cost of existing syntheses based on Ru3(CO)123 has restricted
the application of these complexes.
Previous syntheses involved reacting Ru3(CO)12 with car-
boxylic acids for prolonged periods at high temperature to
produce the polymeric carboxylato complexes, [RuI(RCO2)-
(CO)2]n. These polymers were either directly reacted with a
diimine ligand4 or converted to the acetonitrile adduct prior
to reaction with the bidentate ligand (Scheme 1).5
Figure 1. (A) [RuI2(RCO2)(CO)4(N∧N)2]+ and (B) [RuII(RCO2)2(CO)2-
(N∧N)], where N∧N ) a diimine ligand, such as 2,2′-bipyridine (bpy) or
1,10-phenanthroline (phen).
[RuI(RCO2)(CO)2(L)]2, which is based on the relatively
inexpensive RuCl3‚3H2O precursor (Scheme 2).6 An N-donor
ligand, e.g., pyridine, was reacted with [RuII(CO)2Cl2]n in
the presence of sodium carboxylate to yield [RuI(RCO2)-
(CO)2(L)]2. Here, we report the extension of this synthetic
approach to generate cationic [RuI2(RCO2)(CO)4(N∧N)2]+
We have recently reported a new synthetic route to dimeric
ruthenium(I) complexes incorporating unidentate ligands (L),
* Corresponding author: E-mail: leone.spiccia@sci.monash.edu.au.
Telephone: +61 3 9905 4526. Fax: +61 3 9905 4597.
† Monash University.
‡ University of Western Australia.
(4) Frediani, P.; Bianchi, M.; Salvini, A.; Guarducci, R.; Carluccio, L.
C.; Piacenti, F.; Ianelli, S.; Nardelli, M. J. Organomet. Chem. 1993,
463, 187.
(1) Matteolli, U.; Menchi, G.; Bianchi, M.; Piacenti, F. J. Mol. Catal.
1991, 64, 257.
(2) Frediani, P.; Bianchi, M.; Salvini, A.; Carluccio, L. C.; Rosi, L. J.
Organomet. Chem. 1997, 547, 35.
(3) Crooks, G. R.; Johnson, B. F. G.; Lewis, J.; Williams, I. G. J. Chem.
Soc. A 1969, 2761.
(5) Sherlock, S. J.; Cowie, M.; Singleton, E.; de V. Steyn, M. M.
Organometallics 1988, 7, 1663.
(6) Kepert, C. M.; Deacon, G. B.; Spiccia, L.; Fallon, G. D.; Skelton, B.
W.; White, A. H. J. Chem. Soc., Dalton Trans. 2000, 2867.
10.1021/ic0348401 CCC: $27.50 © 2004 American Chemical Society
Published on Web 12/25/2003
Inorganic Chemistry, Vol. 43, No. 2, 2004 683

Pearson et al.
Scheme 1
Scheme 3
Scheme 2
Scheme 4
complexes. We further report the unexpected formation of
cyclometalated benzoate complexes obtained when [RuII(CO)2-
Cl2]n was reacted with sodium benzoate and bpy or phen.
Although cyclometalation of ligands, particularly phosphines
and phosphites7,8 by ruthenium complexes is known, and has
been extended to, for example, heterocyclic amine ligands,9
aromatic enolates10 and Schiff bases,11 Ru-cyclometalated
benzoates have not been characterized by single-crystal X-ray
diffraction studies. Solution rearrangement of an aryl-
amidobenzoate led to an equilibrium with a Ru-cyclometa-
lated anthranilate but the latter could not be obtained pure,
and an attempted direct ortho-metalation of phenylacetate
failed.12 Although some cyclometalated ruthenium complexes
incorporating aromatic alkanoates have been isolated, viz.,
[Ru(O2CC6H4)(CO)2(PPh3)2]13 and [Ru(O2CC6H3Me)(CO)2-
(PPh3)2],13 their characterization by spectroscopic studies
leaves structural uncertainties.
expected dinuclear RuI complex being obtained. In the case
of N∧N ) 5,6-dmphen, the precipitate obtained was a mixture
of the RuI dinuclear complex, the RuII byproduct and the
free ligand. This “direct addition” method is not general, the
low yields and difficulty in separating the RuI and RuII
products rendering it an unviable synthetic route to
[RuI2(RCO2)(CO)4(N∧N)2]+. However, if the conditions could
be optimized to selectively generate [RuII(MeCO2)2(CO)2-
(N∧N)], this would be an improvement on existing syntheses
that require either long reflux in acetic acid14 or use of silver
carboxylate salts.15
The attempted direct synthesis of [RuI2(PhCO2)(CO)4-
(N∧N)2]+ by the addition of bpy and phen to refluxing
solutions of [Ru(CO)2Cl2]n and sodium benzoate in methanol
yielded crystalline ruthenium(II) complexes incorporating a
cyclometalated benzoate (Scheme 4). The formation of these
complexes was unexpected as the neutral pyridine complex,
[RuI(PhCO2)(CO)2(py)]2, had been successfully made from
[Ru(CO)2Cl2]n.6
An approach that enabled the synthesis of [RuI2(RCO2)-
(CO)4(N∧N)2]+ involved the use of RuI precursors. [RuI-
(MeCO2)(CO)2(py)]2 and [RuI(PhCO2)(CO)2(py)]2 were con-
sidered to be suitable synthons due to their relative ease of
preparation and demonstrated lability of the pyridine ligands.6
Ligand exchange reactions initially performed in refluxing
alcohols resulted in decomposition of the dinuclear core.
Prolonged reaction of an excess of a bidentate ligand with
the complexes under milder conditions (40 °C) in methanol
enabled the substitution of the axially coordinated pyridines
(Scheme 5), hexafluorophosphate being used to precipitate
the cationic product. Use of an aqueous solution of NH4PF6,
instead of KPF6 (which coprecipitated other water insoluble
compounds, e.g., unreacted [Ru(RCO2)(CO)2(py)]2 and di-
imine ligand), gave clean products, with clean electrospray
Results and Discussion
Synthesis. The first approach followed the procedure
outlined in Scheme 2, the unidentate ligand, L, being replaced
with a bidentate ligand, N∧N. The reaction of 4,4′-dimethyl-
2,2′-bipyridine (4,4′-dmbpy) with a refluxing solution of
[RuII(CO)2Cl2]n/NaO2CMe (Scheme 3) gave the dinuclear
[RuI2(MeCO2)(CO)4(4,4′-dmbpy)2]+ complex which precipi-
tated as a chloride/acetate salt (42% yield, cf. 55% for
[RuI(MeCO2)(CO)2(py)]2) and was converted to the PF6- salt.
Attempts to retrieve additional product from the reaction
mixture yielded [RuII(MeCO2)2(CO)2(4,4′-dmbpy)], consist-
ent with reports that [RuII(RCO2)2(CO)2(L)2] was formed in
the reaction mixtures from [RuI(RCO2)(CO)2(L)]2 syntheses.6
When N∧N ) 5,5′-dmbpy, the major product was
[RuII(MeCO2)2(CO)2(5,5′-dmbpy)], only trace amounts of the
(7) Bennett, M. A.; Bruce, M. I.; Matheson, T. W. ComprehensiVe
Organometallic Chemistry; Pergamon: Oxford, England, 1982; Vol.
4, Chapters 32 and 33.
(8) Hill, A. F. ComprehensiVe Organometallic Chemistry; Pergamon:
Oxford, England, 1995; Vol. 7, Chapter 6.
(9) Bardwell, D. A.; Jeffrey, J. C.; Schatz, E.; Tilley, E. E. M.; Ward, M.
D. J. Chem. Soc., Dalton Trans. 1995, 825.
(10) Hartwig, J. F.; Bergman, R. G.; Andersen, R. A. Organometallics 1991,
10, 3326.
(11) Munshi, P.; Samanta, R.; Lahiri, G. K. J. Organomet. Chem. 1999,
586, 176.
(12) Hartwig, J. F.; Bergman, R. G.; Andersen, R. A. J. Am. Chem. Soc.
1991, 113, 6499.
(14) Frediani, P.; Bianchi, M.; Salvini, A.; Guarducci, R.; Carluccio, L. C.
J. Organomet. Chem. 1994, 476, 7.
(15) Black, D. S.; Deacon, G. B.; Thomas, N. C. Aust. J. Chem. 1982, 35,
2445.
(13) Rotem, M.; Shvo, Y. J. Organomet. Chem. 1993, 448, 189.
684 Inorganic Chemistry, Vol. 43, No. 2, 2004

Carbonyl-Carboxylato-Ruthenium Complexes
Scheme 5
signal (half of that for coordinated acetate) and gravi-
metric chloride analysis17 supported the formulation as
[RuI2(MeCO2)(CO)4(4,4′-dmbpy)2](0.5MeCO2/0.5Cl).
Analysis of the IR spectra of [RuII(MeCO2)2(CO)2(N∧N)]
complexes revealed two strong bands attributable to ν(CO)
of cis-terminal carbonyl ligands (2057 and 1996 cm-1 for
N∧N ) 4,4′-dmbpy, 2052 and 1983 cm-1 for N∧N ) 5,5′-
dmbpy; cf., 2058, 1995 cm-1 for [RuII(MeCO2)2(CO)2(bpy)]
and 2060, 1993 cm-1 for [RuII(MeCO2)2(CO)2(phen)]15).
Bands attributable to the νas(CO2) and νs(CO2) vibrational
modes were observed at 1629, 1620, and 1315 cm-1 for N∧N
) 4,4′-dmbpy or N∧N ) 5,5′-dmbpy. A large ν(COO)
separation of ca. 310 cm-1, cf. ionic acetate (∼164 cm-1),
is indicative of unidentate acetate coordination18 and is
similar to that reported for bpy and phen analogues (320-
330 cm-1). 15
The 1H NMR spectrum of [RuII(MeCO2)2(CO)2(4,4′-
dmbpy)] was consistent with a symmetrical geometry,
showing only three resonances arising from the aromatic
protons of the diimine ligand. Combined with the two ν(CO)
frequencies, this indicates an isomer with trans acetate and
cis carbonyl ligands. About 1 month later, the spectrum of
the same NMR solution showed six additional aromatic
signals, consistent with the presence of unsymmetrically
bound 4,4′-dmbpy. An extra carbonyl stretch was observed
in the IR spectrum at 1947 cm-1, which increased in intensity
over time. This product was identified as [Ru(MeCO2)2(CO)-
(4,4′-dmbpy)]2 from the electrospray mass spectrum, which
showed a peak due to [Ru(MeCO2)2(CO)(4,4′-dmbpy)]2H+
at m/z 865. Similar [Ru(CO)2Cl2(N∧N)] complexes under-
go photodecarbonylation to yield the dimers [RuII(CO)-
Cl2(N∧N)]2, which display a single ν(CO) at ∼1945
cm-1.19
and NMR spectra. This approach uses mild conditions,
eliminating the necessity for separation from Ru(II) byprod-
ucts, and was found to be general for [RuI2(RCO2)(CO)4-
(N∧N)2]PF6 complexes: R ) Me, N∧N ) 4,4′-dmbpy, 5,5′-
dmbpy, 5,6-dmphen; R ) Ph, N∧N ) bpy, phen, 5,6-
dmphen.
Characterization. The IR spectra of the [RuI2(RCO2)-
(CO)4(N∧N)2]+ complexes show two bands in the region
2100-1900 cm-1, which can be assigned to ν(COterminal), and
two bands between 1900 and 1700 cm-1 attributable to
ν(CObridging). An absorption in the region 1550-1520 cm-1
results from antisymmetric stretching (νas) of bridging acetate,
while the symmetric stretch (νs) is found in the 1440-1400
cm-1 region. A band at ∼1600 cm-1 is ascribed to CdC or
CdN stretching of the diimine ligands. Frediani et al. have
reported that the νas stretch of the ionic acetate occurs in the
1655-1627 cm-1 region,4 more appropriate for unidentate
acetate. It is expected to be much closer to νas(CO2) of
sodium acetate (1578 cm-1).16 [RuI2(MeCO2)(CO)4(4,4′-
dmbpy)2](0.5MeCO2/0.5Cl) displayed multiple bands in the
region 1560-1520 cm-1, attributable to νas of the pair of
inequivalent acetates (bridging and anionic).
In the IR spectrum of [RuI2(MeCO2)(CO)4(5,6-dmphen)2]-
PF6 (prepared from the RuII precursor) ν(CO) absorptions
additional to those expected for this product were observed
and are attributed to [RuII(MeCO2)2(CO)2(5,6-dmphen)] with
NMR analysis indicating a ∼1:1 ratio of products. These
types of Ru(II) complexes typically display two strong
CO stretching bands at ∼2050 and 1990 cm-1,14,15 which
should obscure the weaker terminal ν(CO) absorptions of
[RuI2(MeCO2)(CO)4(5,6-dmphen)2]PF6. Characteristic bridg-
ing ν(CO) absorptions (at 1801 and 1731 cm-1), however,
prove the presence of [RuI2(MeCO2)(CO)4(5,6-dmphen)2]PF6.
The electrospray mass spectrum also displayed a signal at
m/z 791 corresponding to [RuI2(MeCO2)(CO)4(5,6-dmphen)2]+.
The 1H NMR spectra of [RuI2(RCO2)(CO)4(N∧N)2]+
indicate that these complexes have a high degree of sym-
metry so that the halves of the diimine ligands behave
identically. Coordination of the diimine ligands to the
diruthenium core caused the proton resonances to shift
downfield relative to the free ligands (e.g., protons in the
5,5′ and 6,6′ positions of dmbpy by 0.9 and 1.5 ppm,
respectively and by >1.2 ppm for the aromatic protons of
5,6-dmphen). When R ) Me, the spectrum displayed singlets
at ca. 1 and 1.9 ppm attributable to the methyl group of the
bridging acetate and unbound acetate, respectively. For
[RuI2(MeCO2)(CO)4(4,4′-dmbpy)2]+, the integration of this
The cyclometalated benzoate complexes, [RuII(O2CC6H4)-
(CO)2(N∧N)] (N∧N ) bpy, phen), like the diacetate com-
plexes, display two strong IR absorptions in the region
2050-1960 cm-1, attributable to ν(CO) of cis-terminal
carbonyls. The νas(COO) and νs(COO) absorptions also
showed large separations (∼300 cm-1), relative to that of
ionic benzoate (140 cm-1), and in agreement with those
observed for [(C5Me5)M(O2CC6H4)(DMSO)] (300-330 cm-1
for M ) Rh, Ir) which also contain O,C-bound benzoate(s).20
1
The H NMR spectra, assigned with reference to the
chemical shifts and coupling constants for the benzoate
resonances of [Os(p-MeC6H4CHMe2)(O2CC6H4)(DMSO)],20
exhibited the signals expected for cyclometalated benzoate
complexes. The 13C NMR spectra of the cyclometalated
products reported here showed a signal due to the ruthenium
bound carbon at 165 ppm, the other benzene carbon signals
being in the region 125-141 ppm. The former corresponded
well to those of [Os(p-MeC6H4CHMe2)(O2CC6H4)(DMSO)]
(17) Vogel, A. I. Vogel’s Textbook of QuantitatiVe Inorganic Analysis, 4th
ed.; Longmans: New York, 1981.
(18) Deacon, G. B.; Phillips, R. J. Coord. Chem. ReV. 1980, 33, 227.
(19) Deacon, G. B.; Kepert, C. M.; Sahely, N.; Skelton, B. W.; Spiccia,
L.; Thomas, N. C.; White, A. H. J. Chem. Soc., Dalton Trans. 1999,
275.
(16) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coor-
dination Compounds, 4th ed.; John Wiley & Sons: 1986.
(20) Kisenyi, J. M.; Sunley, G. J.; Cabeza, J. A.; Smith, A. J.; Adams, H.;
Salt, N. J.; Maitlis, P. M. J. Chem. Soc., Dalton Trans. 1987, 2459.
Inorganic Chemistry, Vol. 43, No. 2, 2004 685

Pearson et al.
Table 1. Ruthenium Environments, [RuII(MeCO2)2(CO)2(N∧N)], N∧N
) 4,4′/5,5′-dmbpya
atomb
r
N(1*)
C(1)
C(1*)
O(11)
O(11*)
N(1)
N(11)
N(21)
2.103(3) 77.6(1)
96.7(1) 174.2(1) 87.5(1)
98.8(5) 174.8(5) 83.8(3)
96.5(5) 176.1(5) 85.7(4)
84.4(1)
87.2(3)
85.5(3)
2.12(1)
2.12(1)
78.1(4)
78.1(4)
N(1*) (2.103(3))
N(11′) 2.12(1)
N(21′) 2.13(1)
(174.2(1)) (96.7(1)) (84.4(1)) (87.5(1))
176.9(5)
174.6(5)
96.6(5) 85.9(3)
98.0(5) 84.8(3)
85.9(3)
86.6(3)
C(1)
C(110) 1.89(1)
C(210) 1.83(1)
1.885(4)
89.1(2) 96.5(2)
86.5(6) 94.0(4)
87.4(6) 95.5(4)
90.9(2)
93.8(4)
92.4(4)
C(1*) (1.885(4))
C(120) 1.86(1)
C(220) 1.86(1)
(90.9(2)) (96.5(2))
95.9(4)
93.7(5)
92.6(4)
94.6(5)
Figure 3. Molecular projection of the [RuI2(MeCO2)(CO)4(5,5′-dmbpy)2]+
cation.
O(11)
2.072(3)
169.6(1)
168.9(3)
168.8(3)
O(111) 2.092(7)
O(211) 2.063(8)
Table 2. Ruthenium Environments, [RuI2(MeCO2)(Co)4(5,5′-dmbpy)2]+
O(11*) (2.072(3))
O(121) 2.073(7)
O(221) 2.073(7)
atom
r
N(1′)
C(10)
C(10*)
C(20)
O(11)
N(1)
N(1′)
C(10)
C(10*) 2.021(5)
C(20)
O(11)
2.190(4) 74.7(1) 169.1(2)
2.175(4)
2.010(5)
95.1(2) 95.4(2)
81.6(2)
84.0(2)
93.2(2)
90.8(2)
174.7(2)
95.3(2) 169.2(1) 91.0(2)
94.5(2) 89.2(2)
93.8(2)
a r (Å) is the Ru-ligand atom distance; other entries in the matrix are
the angles (deg) subtended by the relevant entries at the head of the row
and column. b The three values in each entry are for the N∧N ) 4,4′-dmbpy,
N∧N ) 5,5′-dmbpy (two molecules) adducts respectively; the single “atom”
entries across the head of the table imply the use of the other associates as
appropriate. Asterisked atom entries for the 4,4′-dmbpy adduct are generated
by the intramolecular 2-axis, redundant entries being given in parentheses
(see also Table 2).
1.856(5)
2.109(5)
arrangement. Since Ru(II) is kinetically inert (d6 configura-
tion), undergoing only slow ligand exchange at room
temperature, the solid state and initial solution structures
1
should correspond within the H NMR time frame. For the
4,4′-dmpby and 5,5′-dmpby complexes, X-ray studies showed
a trans-acetato-cis-carbonyl ligand arrangement (Figures 2
and 3) in agreement with the structure proposed by Black et
al.15 and consistent with the 1H NMR data. NMR studies of
[RuII(MeCO2)2(CO)2(bpy)], prepared by the method of
15
Black et al.
indicated that both cis and trans acetate
complexes are present initially, but the trans isomer converts
to the cis isomer over a prolonged time.
[RuII(MeCO2)2(CO)2(4,4′-dmbpy)] crystallizes (modeled
as a dichloromethane hemisolvate) with half of the formula
unit comprising the asymmetric unit of the structure, the six-
coordinate ruthenium being disposed on a crystallographic
2-axis which passes through the midpoint of the central C-C
bond of the bipyridine component, relating the cis-carbonyl
and trans-O-acetato pairs of ligands. The structure is more
precisely established than that of its [RuII(MeCO2)2(CO)2-
(5,5′-dmbpy)] counterpart, wherein two complete molecules,
pseudo symmetrically related, comprise the asymmetric unit
of the structure. The geometries about the ruthenium atoms
show no pronounced differences (Table 1). In both cases,
the trans-acetato-O donors bow toward the aromatic chelate,
presumably in consequence of its small bite (Figure 2); an
interesting difference between the two structures is found in
the relative dispositions of the pairs of acetate planessin
the 5,5′-dmbpy adduct the uncoordinated acetate oxygen
atoms lie disposed between the pair of cis-carbonyl groups,
thus: O(12)‚‚‚O(110, 120) 3.43(1), 3.16(1) Å; O(122)‚‚‚
O(110, 120) 3.12(1), 3.26(1) Å; O(212)‚‚‚O(210, 220) 3.14(1),
3.34(1) Å; O(222)‚‚‚O(210, 220) 3.23(1), 3.15(1) Å. The
pairs within each molecule are thus slightly disposed to either
side of the putative mirror plane passing through the
Figure 2. Molecular projection of [RuII(MeCO2)2(CO)2(N∧N)], N∧N )
4,4′-dmbpy (ruthenium site symmetry 2). The two molecules of the 5,5′-
dmbpy adduct are similar, albeit lacking crystallographic symmetry.
(156 ppm) and [Ru(O2CC6H4)(PPh3)2(CO)2] (171 ppm).13
Electrospray mass spectroscopy supported the formulation
of [RuII(O2CC6H4)(CO)2(N∧N)] with signals corresponding
to [complex]H+ being observed at m/z 435 (bpy) and 459
(phen).
Crystallography. Single-crystal X-ray structure determi-
nations were undertaken for [RuII(MeCO2)2(CO)2(4,4′-
dmbpy)], [RuII(MeCO2)2(CO)2(5,5′-dmbpy)], [RuII(O2CC6H4)-
(CO)2(N∧N)] ((N∧N ) bpy, phen), and [RuI2(MeCO2)-
(CO)4(5,5′-dmbpy)2]PF6. The assignment of the stereochem-
istry of [RuII(MeCO2)2(CO)2(N∧N)] complexes on the basis
of NMR spectroscopy has been debated. Black et al.15
assigned the prevalent geometry as trans-carboxylate-cis-
carbonyl, while Frediani et al.14 proposed an all cis-
686 Inorganic Chemistry, Vol. 43, No. 2, 2004

Carbonyl-Carboxylato-Ruthenium Complexes
Figure 4. Molecular projection of [RuII(C6H4CO2)(CO)2(phen, bpy)].
Table 3. Ruthenium Environments, [RuII(C6H4CO2)(CO)2L], L ) Bpy,
coordinated carboxylate oxygens, the overall molecular
symmetry approaching 2m. By contrast, in the 4,4′-dmbpy
adduct, the carboxylates are twisted (necessarily, in opposite
directions) about the O-Ru-O axis, so that the uncoordi-
nated carboxylate oxygens lie outside the pair of cis-carbonyl
groupssO(12)‚‚‚O(1) is 2.970(7) Å, with τ (C(11)-O(11)-
Ru-C(1)) being 15.8(3)° and the overall symmetry reduced
to 2. O-Ru-O angles are similar in both compounds, but
Ru-O-C in the 4,4′-dmbpy complex (124.6(3)°) is larger
than the counterparts in the 5,5′-dmbpy adduct (range
120.8(8)-122.1(7)°). No significant concomitant change is
observed in Ru-O lengths. The O-Ru-O angle, ca. 169°
in these complexes, may be contrasted with the Cl-Ru-Cl
angle (176.3(1)°) in the chloro counterpart [RuIICl2(CO)2-
(bpy)];21 Ru-C, N in the latter (1.83(2), 2.11(1) Å ( )) are
similar to the present values. The 4,4′-dmbpy ligand itself,
for which a redetermination of superior precision is re-
ported herein,22,23 (see Supporting Information) adopts, as
might be expected, a centrosymmetric trans conformation.
[Ru2(MeCO2)(CO)4(5,5′-dmbpy)2](PF6) (Table 2, Figure 3)
crystallizes (modeled as a 1/3 methanol solvate) with half of
the formula unit comprising the asymmetric unit of the
structure, the binuclear cation disposed with a crystal-
lographic 2-axis passing through the C-C bond of the acetate
ligand and the midpoint of the Ru‚‚‚Ru line. The C2O2
skeleton of the acetate is thus obligate planar; of smaller
“bite” (O‚‚‚O 2.243(5) Å) than the Ru‚‚‚Ru distance (2.7021(5)
Å). Concomitant with its bridging function we find the trans
axes through the two µ-carbonyl groups divergent and the
Ru(µ-CO)2Ru four-membered ring nonplanar, the “fold”
dihedral angle at the C‚‚‚C line being 18.5(2)°, with the
carbonyl groups essentially collinear (ø2 ) 1143). Geometries
about the metal are otherwise similar to those found in the
counterpart species [Ru2(MeCO2)(CO)4(N∧N)2]+, N∧N )
phen,4 bpy,24 and “dpa” ()bis(2-pyridyl)amine).25
Phena
atom
N(1)
r
N(1′)
C(10)
C(20)
O(11)
C(12)
2.171(3) 76.8(1) 101.1(1) 99.7(2)
2.165(3) 77.4(1) 102.4(1) 99.6(1)
86.4(1) 163.7(1)
82.9(1) 161.7(1)
N(1′)
2.133(3)
2.133(3)
177.7(1) 92.2(1)
178.0(1) 90.0(1)
88.9(2)
85.2(1)
84.8(1)
93.9(2)
97.2(1)
172.8(1)
173.6(1)
92.6(1)
93.4(1)
89.4(1)
87.4(1)
93.0(2)
96.2(1)
80.4(1)
80.5(1)
C(10) 1.890(4)
1.874(4)
C(20) 1.860(5)
1.857(4)
O(11) 2.102(3)
2.091(2)
88.1(2)
C(12) 2.062(4)
2.065(3)
aValues for the bpy complex are above those for the phen adduct.
Figure 5. Unit cell projection of [RuII(O2CC6H4)(CO)2(bpy)], down a
showing the hydrogen-bonding interactions.
confirm their isolation as solvates. A few examples of
ruthenium cyclometalated aromatic carboxylates are known,
[Ru(O2CC6H3NH2)(PPh3)4],12 [Ru(O2CC6H4)(CO)2(PPh3)2]13
and [Ru(O2CC6H3Me)(CO)2(PPh3)2],13 but [RuII(O2CC6H4)-
(CO)2(bpy, phen)] appear to be the first to be structurally
characterized. Other transition metal complexes incorporating
a O,C-chelating benzoate to be structurally characterized
include [Ir(O2CC6H4)(Cp*)(DMSO)]26 (O-Ir-C 78.4(10)°,
Ir-C 2.08(3) Å, Ir-O 2.09(2) Å); [Pt(O2CC6F4)(PPh3)(2,6-
Me2py)]27 (Pt-C 2.01(2), Pt-O 2.06(1), C-O 1.28(2), CdO,
1.24(2) Å. C-Pt-O 81.9(5)°). A comparison of the geo-
metric features of the benzoate chelate in [RuII(O2CC6H4)-
(CO)2(bpy, phen)] (Table 3, Figure 4) with those exhibited
The structures of [RuII(O2CC6H4)(CO)2(bpy, phen)] es-
tablish the formation of cyclometalated benzoate products,
resolve the isomer issue (-C(O)O- trans to CO or N), and
(21) Haukka, M.; Kiviaho, J.; Ahlgre´n, M.; Pakkanen, T. A. Organo-
metallics 1995, 14, 825.
(22) Shuangxi, L.; Ying, Z.; Linpei, J. Beijing Shifan Dax. Xue., Zir. Kex.
1996, 32, 371.
(23) Beswick, M. A.; Davies, J. E. CCDC NAMKAN (private communica-
tion).
(24) de V. Steyn, M. M.; Singleton, E. Acta Crystallogr. C 1988, 44, 1722.
(25) Kepert, C. M.; Deacon, G. B.; Spiccia, L. Inorg. Chim. Acta 2003,
355C, 213.
(26) Kisenyi, J. M.; Cabeza, J. A.; Smith, A. J.; Adams, H.; Sunley, G. J.;
Salt, N. J.; Maitlis, P. M. J. Chem. Soc., Chem. Commun. 1985, 770.
(27) Anastasiou, D.; Deacon, G. B.; Gatehouse, B. M. J. Organomet. Chem.
1987, 329, 267.
Inorganic Chemistry, Vol. 43, No. 2, 2004 687

Pearson et al.
Method 1. [RuI2(MeCO2)(CO)4(4,4′-dmbpy)2](0.5MeCO2/0.5Cl)
(89 mg, 0.11 mmol) was dissolved in methanol (15 mL) by heating
the mixture in a water bath at 50 °C with stirring. Addition of a
methanolic solution (5 mL) of KPF6 (28 mg, 1.5 mmol) immediately
precipitated pale yellow [RuI2(MeCO2)(CO)4(4,4′-dmbpy)2](PF6)
(Yield: 79 mg, 80%). Anal. Calcd for C30H27F6N4O6PRu2
{[RuI2(MeCO2)(CO)4(4,4′-dmbpy)2](PF6)}: C, 40.6; H, 3.1; N, 6.3.
by these complexes shows similar chelate angles and M-C
and M-O distances despite differences in the metal centers.
In the present complexes, as in the other structures, the
interleaving or overlapping of the planar bidentate ligands
are dominant motifs throughout the lattice arrays (representa-
tive cell projections have been deposited). Also of signifi-
cance is the hydrogen bonding in the hydrated bpy cyclo-
metalated adduct, the water molecules bridging successive
inversion related substrate molecules via their carboxylate
groups into a string parallel to the b axis (Figure 5). This
structure lends credence to the claim (from microanalyses)
that [RuII(XC6H3CO2)(CO)2(PPh3)2] (X ) H, Me) were
isolated as hydrates.
Found: C, 40.6; H, 3.3; N, 6.4. Infrared Spectrum (KBr disk), cm-1
:
2021 s, 1961 m, 1804 w, 1737 s, 1620 m, 1527 m, 1493 m, 1448
m, 1421 m, 1318 w, 1242 w, 1021 w, 916 w, 847 s, 709 m, 670 w,
559 m, 515 w, 422 w. 1H NMR spectrum (d6-acetone): 1.00 (3H,
s, µ-CH3CO2), 2.73 (12H, s, bpy-CH3), 8.03 (4H, d, bpy-H5), 8.77
(4H, s, bpy-H3), 10.08 (4H, d, bpy-H6). Electrospray mass spectrum
(acetone:methanol 1:1): m/z 743 (100%, [RuI2(MeCO2)(CO)4(4,4′-
dmbpy)2]+).
Method 2. [RuI(MeCO2)(CO)2(py)]2 (78 mg, 0.13 mmol) and
4,4′-dimethyl-2,2′-bipyridine (100 mg, 0.54 mmol) were suspended
in HPLC grade methanol (20 mL) in a quickfit round-bottomed
flask. The suspension was sonicated for several minutes until the
4,4′-dimethyl-2,2′-bipyridine had dissolved and the sealed vessel
was incubated in a thermostatically controlled water bath at 40 °C
for 24 h. The addition of aqueous potassium hexafluorophosphate
(5 mL, 1.0 M) induced the precipitation of a fine orange/yellow
powder which was collected by filtration and washed with cold
ethanol and diethyl ether before drying in air at 70 °C. (Yield: 0.109
g, 87%.) Anal. Calcd for C30H27F8K1/3N4O6P4/3Ru2 {[RuI2(MeCO2)-
(CO)4(4,4′-dmbpy)2]PF6‚1/3KPF6}: C, 38.0; H, 2.9; N, 5.9.
Experimental Section
Physical Measurements. Infrared spectra were recorded using
a Perkin-Elmer 1640 FTIR spectrophotometer. H NMR spectra
1
were recorded on a Bruker DPX300 spectrometer or Varian
Mercury 300 spectrometer, both operating at 300 MHz. Unresolved
doublets of doublets giving rise to apparent triplets are denoted by
an asterisk. Electrospray mass spectra were recorded on Micromass
Platform Quadrupole mass spectrometer fitted with an electrospray
source. Peaks are listed according to the most intense signal within
an isotopic distribution pattern. For Ru2 containing ions, this is one
of two nearly equal intensity peaks, corresponding to the natural
isotopic distribution of constituent elements.
Found: C, 38.1; H, 2.9; N, 6.0. Infrared spectrum (Nujol) cm-1
:
Materials and Reagents. Most materials and reagents were of
reagent or analytical reagent grade and used as received without
further purification. 3-Methylpyridine was distilled prior to use.
3132 w, 3078 w, 2012 s, 1958 s, 1805 m, 1737 s, 1617 s, 1529 s,
1491 s, 1318 m, 1296 m, 1242 m, 1140 w, 1038 w, 1022 m, 986
1
28
[Ru(CO)2Cl2]n and 5,5′-dmbpy29 were synthesized according to
w, 916 m, 850 s ν(PF6); 739 s. H NMR spectrum (d6-acetone):
1.01 (3H, s, CH3CO2); 2.73 (12H, s, bpy-CH3); 8.03 (4H, dd,
H5,H5′); 8.77 (4H, s, H3,H3′); 10.08 (4H, d, H6,H6′). Electrospray
mass spectrum (acetone): m/z 743 (100%, [RuI2(MeCO2)(CO)4-
(4,4′-dmbpy)2]+).
literature methods.
Syntheses.
µ-O,O′-Acetatodi-µ-C,C-carbonyl-di-C,C-car-
bonylbis(4,4′-dimethyl-2,2′-bipyridine)diruthenium(I) Acetate/
Chloride. [Ru(CO)2Cl2]n (274 mg, 1.20 mmol) was added to a
degassed solution of sodium acetate (1.20 g, 14.6 mmol) in
methanol (25 mL). The reaction mixture was refluxed under
nitrogen, at a bath temperature of 110°C. After 4 h, 4,4′-dmbpy
(264 mg, 1.43 mmol) was added to the pale orange solution,
resulting in an instant color change to bright red/orange. After
heating for a further 15 min, the reaction mixture was cooled
overnight in a refrigerator, giving a yellow precipitate in an orange
solution. The product, [RuI2(MeCO2)(CO)2(4,4′-dmbpy)2](0.5MeCO2/
0.5Cl) (yield: 199 mg, 42%), was collected by filtration and dried
in air at 70 °C (the filtrate yielded [RuII(MeCO2)2(CO)2(4,4′-
dmbpy)]). It was converted to the hexafluorophosphate salt as
indicated below. Infrared spectrum (KBr disk), cm-1: 2017 s, 1968
m, 1801 w, 1734 s, 1619 m, 1562 m, 1494 m, 1419 m, b, 1243 w,
µ-O,O′-Acetatodi-µ-C,C-carbonyldi-C,C-carbonylbis(5,5′-di-
methyl-2,2′-bipyridine)diruthenium(I) Hexafluorophosphate.
Method 2 for the preparation of [RuI2(MeCO2)(CO)4(4,4′-dmbpy)2]-
(PF6) was followed using [RuI(MeCO2)(CO)2(py)]2 (82 mg, 0.14
mmol) with 5,5′-dimethyl-2,2′-bipyridine (0.146 g, 0.79 mmol). The
less soluble hexafluorophosphate salt was formed on addition of
ammonium hexafluorophosphate (0.125 mg, 0.68 mmol), followed
by sonication for a period of 5 min. [RuI2(MeCO2)(CO)4(5,5′-
dmbpy)2](PF6) was then isolated as previously described. (Yield:
0.126 g, 96%.) Anal. Calcd for C30H27F6N4O6PRu2 {[RuI2(MeCO2)-
(CO)4(5,5′-dmbpy)2]PF6}: C, 40.6; H, 3.1; N, 6.3. Found: C, 40.3;
H, 3.1; N, 6.5. Infrared spectrum (Nujol) cm-1: 2017 s, 1974 s,
1811 m, 1755 s, 1602 w, 1584 w, 1525 s, 1482 s, 1348 w, 1326 w,
1321 w, 1298 w, 1243 m, 1164 m, 1144 w, 1068 w, 1050 m, 1029
1
1020 w, 834 w, 714 m, 623 w, 514 w. H NMR spectrum (d4-
1
methanol): 0.99 (3H, s, µ-CH3CO2), 1.89 (1.5H, s, CH3CO2-), 2.70
(12H, s, bpy-CH3), 7.87 (4H, d, bpy-H5), 8.61 (4H, s, bpy-H3),
10.05 (4H, d, bpy-H6). Electrospray mass spectrum (meth-
anol): m/z 743 (100%, [RuI2(MeCO2)(CO)4(4,4′-dmbpy)2]+).
Chloride analysis. Found: Cl-, 2.1. Calcd for C30H27ClN4O6Ru2
{[RuI2(MeCO2)(CO)4(4,4′-dmbpy)2](Cl)}: Cl-, 4.6. Calcd for
C31H28.5Cl0.5N4O6Ru2 {[RuI2(MeCO2)(CO)4(4,4′-dmbpy)2](0.5MeCO2/
0.5Cl)}: Cl-, 2.3.
w, 932 w, 844 s, 730 w (sh), 706 s, 652 w, 620 w. H NMR
spectrum (d6-acetone): 1.01 (3H, s, CH3CO2); 2.79 (12H, s, bpy-
CH3); 8.33 (4H, dd, H4,H4′); 8.73 (4H, d, H3,H3′); 10.08 (4H, m,
H6,H6′). Electrospray mass spectrum (acetone): m/z 743 (100%,
[RuI2(MeCO2)(CO)4(5,5′-dmbpy)2]+).
µ-O,O′-Acetatodi-µ-C,C-carbonyldi-C,C-carbonylbis(5,6-di-
methyl-1,10-phenanthroline)diruthenium(I) Acetate/Chloride.
Method 1. [RuI2(MeCO2)(CO)4(5,6-dmphen)2](MeCO2/Cl) was
synthesized in a fashion similar to [RuI2(MeCO2)(CO)4(4,4′-
dmbpy)2](MeCO2/Cl) by reaction between [Ru(CO)2Cl2]n (185 mg,
0.81 mmol) and NaO2CMe (900 mg, 110 mmol), followed by
addition of 5,6-dmphen (173 mg, 0.830 mmol) after 5.5 h. The
mixture was refrigerated overnight giving a pale orange precipitate
of [RuI2(MeCO2)(CO)4(5,6-dmphen)2](MeCO2/Cl) and colorless
µ-O,O′-Acetatodi-µ-C,C-carbonyldi-C,C-carbonylbis(4,4′-di-
methyl-2,2′-bipyridine)diruthenium(I) Hexafluorophosphate.
(28) Anderson, P. A.; Deacon, G. B.; Haarmann, K. H.; Keene, F. R.;
Meyer, T. J.; Reitsma, D. A.; Skelton, B. W.; Strouse, G. F.; Thomas,
N. C.; Treadway, J. A.; White, A. H. Inorg. Chem. 1995, 34, 6145.
(29) Badger, G. M.; Sasse, W. H. F. AdV. Heterocycl. Chem. 1963, 2, 179.
688 Inorganic Chemistry, Vol. 43, No. 2, 2004

Carbonyl-Carboxylato-Ruthenium Complexes
crystals (169 mg crude). Infrared spectrum (KBr disk), cm-1: 2055
vs, 2016 m (sh), 1989 vs, 1801 vw, 1731 m, 1630 m, 1600 m,
1524 w, 1433 m, 1376 m, 1313 m, 1020 w, 814 m, 728 m, 695 m.
A methanol suspension of the solid was gently heated on a water
bath at 40 °C until the solid had completely dissolved. Addition of
a methanolic solution (10 mL) of KPF6 (140 mg, 0.76 mmol) to
the solution containing [RuI2(MeCO2)(CO)4(5,6-dmphen)2](MeCO2/
Cl) deposited a precipitate. Filtration of the mixture yielded a gray
precipitate and an orange filtrate. Reduction of the volume of the
filtrate under vacuum precipitated a solid mixture of [RuI2(MeCO2)-
(CO)4(5,6-dmphen)2](PF6) and [RuII(MeCO2)2(CO)2(5,6-dmphen)]
in ∼1:1 ratio, which was collected by filtration and dried in vacuo
(yield: 67 mg, ∼9% of RuI complex, ∼8% of RuII complex).
Infrared spectrum (KBr disk), cm-1: 3413 w, 3085 w, 2929 w,
2055 vs, 2013 s (sh), 1990 vs, 1803 w, 1733 s, 1630 s, 1603 s,
1544 w, 1524 w, 1483 vw, 1434 s, 1377 m, 1312 s, 1174 w, 1040
w, 844 s, 813 m (sh), 728 m, 682 m, 636 w, 596 w, 559 w, 522 w.
1HNMRspectrum(d6-acetone): [RuI2(MeCO2)(CO)4(5,6-dmphen)2]-
(PF6): 0.82 (3H, s, µ-CH3CO2), 3.00 (12H, s, phen-CH3), 8.57
(4H, dd, H3,H8), 9.28 (4H, dd, H4,H7), 10.61 (4H, dd, H2,H9).
Other product {[RuII(MeCO2)2(CO)2(5,6-dmphen)]}: 1.43 (6H, s,
CH3CO2-), 2.96 (6H, s, phen-CH3), 8.17 (2H, dd, H3′,H8′), 9.08
(2H, dd, H4′,H7′), 9.59 (2H, dd, H2′,H9′). Electrospray mass
spectrum (acetone): m/z 791 (100%, [RuI2(MeCO2)(CO)4(5,6-
dmphen)2]+).
mmol). (Yield: 115 mg, 64%.) Infrared spectrum (Nujol) cm-1
:
2019 s, 1978 s, 1808 m, 1741 s, 1630 w, 1603 w, 1593 w, 1538 s,
1520 m, 1434 m, 1413 s, 1307 w, 1227 w, 1175 w, 1149 w, 1026
1
w, 976 w, 931 w, 861 s, 851 s, 785 w, 717 m. H NMR spectrum
(d6-acetone): 6.33 (2H, d, benz-H2); 6.69 (2H, t*, benz-H3); 7.04
(1H, t, benz-H4); 8.52 (4H, s, phen-H5,H6); 8.58 (4H, dd, phen-
H3,H8); 9.18 (4H, dd, phen-H4,H7); 10.67 (4H, dd, phen-H2,H9).
Electrospray mass spectrum (acetone): m/z 797 (100%, [RuI2(PhCO2)-
(CO)4(phen)2]+), 769 (30%, [RuI2(PhCO2)(CO)3(phen)2]+), 740
(32%, [RuI2(PhCO2)(CO)2(phen)2]+).
µ-O,O′-Benzoatodi-µ-C,C-carbonyldi-C,C-carbonylbis(5,6-
dimethyl)-1,10-phenanthroline)diruthenium(I) Hexafluorophos-
phate. [RuI2(PhCO2)(CO)4(5,6-dmphen)2](PF6) was synthesized in
a fashion similar to [RuI2(MeCO2)(CO)4(5,5′-dmbpy)2](PF6) by
reaction between [RuI(PhCO2)(CO)2(py)]2 (143 mg, 0.152 mmol)
and 5,6-dimethyl-1,10-phenanthroline (148 mg, 0.711 mmol). The
product was isolated as a brown/orange powder. (Yield: 132 mg,
87%). Infrared spectrum (Nujol) cm-1: 2016 s, 1974 m, 1808 m,
1740 s, 1612 w, 1529 m, 1415 s, 1310 w, 1177 w, 1130 w, 1087
1
w, 1037 w, 879 w, 844 s, 729 m, 697 m. H NMR spectrum (d6-
acetone): 3.02 (12H, s, phen-CH3); 6.33 (2H, dd, benz-H2); 6.69
(2H, t*, benz-H3); 7.04 (1H, t, benz-H4); 8.56 (4H, dd, phen-
H3,H8); 9.29 (4H, dd, phen-H4,H7); 10.64 (4H, dd, phen-H2,H9).
Electrospray mass spectrum (acetone): m/z 853 (100%, [RuI2(PhCO2)-
(CO)4(5,6-dmphen)2]+).
Method 2. 5,6-Dimethyl-1,10-phenanthroline (138 mg, 0.66
mmol) and [RuI(MeCO2)(CO)2(py)]2 (118 mg, 0.200 mmol) were
reacted according to the process used to prepare [RuI2(MeCO2)-
(CO)4(5,5′-dmbpy)2](PF6), resulting in the isolation of fine, pale
orange needles of [RuI2(MeCO2)(CO)4(5,6-dmphen)2](PF6). (Yield:
176 mg, 72%.) Anal. Calcd for C34H27F6N4O6PRu2‚1/6NH4PF6
{[RuI2(MeCO2)(CO)4(5,6-dmphen)2](PF6)‚1/6NH4PF6}: C, 42.5; H,
2.9; N, 6.1. Found: C, 42.6; H, 2.9; N, 6.1. Infrared spectrum
(Nujol) cm-1: 2023 s, 1992 m, 1984 w (sh), 1968 m, 1806 m,
1732 s, 1600 w, 1586 w, 1548 m, 1440 s, 1348 w, 1310 w, 1201
w, 1176 w, 1118 w, 1084 w, 1040 w, 960 w, 846 s, 816 w (sh),
trans-Di-O,O-acetato-cis-di-C,C-carbonyl(4,4′-dimethyl-2,2′-
bipyridine)ruthenium(II). The orange filtrate from [RuI2(MeCO2)-
(CO)4(4,4′-dmbpy)2](0.5MeCO2/0.5Cl) was evaporated to dryness,
resulting in a mixture of sodium acetate and [RuII(MeCO2)2(CO)2-
(4,4′-dmbpy)]. Suspension of the residue by addition of CH2Cl2,
and filtration yielded an orange solution of [RuII(MeCO2)2(CO)2-
(4,4′-dmbpy)]. On evaporation, the orange complex still contained
a light colored solid. The residue was suspended in CH2Cl2 and
filtered to yield a yellow powder of [RuII(MeCO2)2(CO)2(4,4′-
dmbpy)] (yield: 160 mg, 29%). Infrared spectrum (KBr disk), cm-1
:
2057 s, 1996 s, 1620 s, b, 1376 m, 1315 m, 1036 w, 834 w, 678
w, 513 w. After exposure to light the powder started to change to
an orange color and was recrystallized from methanol, giving a
yellow/orange crystalline substance. Recrystallization was repeated
from CH2Cl2 to give single crystals suitable for X-ray crystal-
lography. Infrared spectrum (KBr disk), cm-1: 2058 s, 1991 s,
{1947 m ν(CO) of [RuII(MeCO2)2(CO)(4,4′-dmbpy)]2}, 1702 w,
1
804 w (sh), 646 w, 619 w. H NMR and mass spectra were in
agreement with those for the product from method 1.
µ-O,O′-Benzoatodi-µ-C,C-carbonyldi-C,C-carbonylbis(2,2′-bi-
pyridine)diruthenium(I) Hexafluorophosphate. The conditions
used to prepare [RuI2(MeCO2)(CO)4(5,5′-dmbpy)2](PF6) were em-
ployed to form [RuI2(PhCO2)(CO)4(bpy)2](PF6). The product was
collected as a light orange powder after the reaction between
[RuI(PhCO2)(CO)2(py)]2 (129 mg, 0.181 mmol) and 2,2′-bipyridine
(164 mg, 1.05 mmol). (Yield: 0.135 g; 84%.) Anal. Calcd for
C31H21F6N4O6PRu2 {[RuI2(PhCO2)(CO)4(bpy)2](PF6)}: C, 41.7; H,
2.4; N, 6.3. Found: C, 41.3; H, 2.2; N, 6.4. Infrared spectrum
(Nujol) cm-1: 2013 s, 1983 m, 1809 m, 1741 s, 1602 m, 1594 w,
1567 w, 1531 s, 1461 m, 1444 m, 1417 s, 1236 m, 1246 w, 1176
w, 1162 w, 1076 w, 1045 w, 1025 w, 917 w, 897 w, 856 s, 840 s,
767 m, 717 m, 653 w. 1H NMR spectrum (d6-acetone): 6.68 (2H,
dd, benz-H2); 6.89 (2H, t*d, benz-H3); 7.18 (1H, tt, benz-H4);
8.21 (4H, ddd, bpy-H5,H5′); 8.56 (4H, t*d, bpy-H4,H4′); 8.98 (4H,
d, bpy-H3,H3′); 10.31 (4H, dt*, bpy-H6,H6′). Electrospray mass
spectrum (acetone): m/z 693 (65%, [RuI2(PhCO2)(CO)2(bpy)2]+),
721 (40%, [RuI2(PhCO2)(CO)3(bpy)2]+), 749 (100%, [RuI2(PhCO2)-
(CO)4(bpy)2]+).
1
1620 s, b, 1544 w, 1382 m, 1323 m, 671 s. H NMR spectrum
(d6-acetone): trans-cis-[RuII(MeCO2)2(CO)2(4,4′-dmbpy)]: 1.57
(6H, s, CH3CO2-); 2.64 (6H, s, bpy-CH3); 7.60 (2H, d, H5,H5′);
1
8.47 (2H, s, H3,H3′); 9.05 (2H, d, H6,H6′). One month later, H
NMR spectrum (d6-acetone): {∼1:1 mixture of (i) trans-cis-
[RuII(MeCO2)2(CO)2(4,4′-dmbpy)] and (ii) [RuII(MeCO2)2(CO)(4,4′-
dmbpy)]2}: (i) 1.53 (6H, s, CH3CO2-), 2.65 (6H, s, bpy-CH3), 7.65
(2H, d, H5,H5′), 8.55 (2H, s, H3,H3′), 9.09 (2H, d, H6,H6′), and
(ii) 1.51 (6H, s, CH3CO2-), 2.60 (3H, s, bpy-CH3′), 2.72 (3H, s,
bpy-CH3), 7.36 (1H, d, H5′), 7.81 (1H, d, H5), 8.46 (1H, s, H3′),
8.60 (1H, s, H3′); 8.90 (1H, d, H6′), 9.22 (1H, d, H6). Infrared
spectrum (Nujol) cm-1
: 2056 s, 1989 s, {1946 s ν(CO) of
[RuII(MeCO2)2(CO)(4,4′-dmbpy)]2}, 1620 s, b, 1318 m, 837 w, 721
w. Electrospray mass spectrum (methanol): m/z 405 (100%, [M -
2CO + H]+), 437 (55%, [M - 2CO + MeOH + H]+), 461 (30%,
[M + H]+), 483 (35%, [M + Na]+), 865 (5%, [RuII(MeCO2)2(CO)-
(4,4′-dmbpy)]2H+).
µ-O,O′-Benzoatodi-µ-C,C-carbonyldi-C,C-carbonylbis(1,10-
phenanthroline)diruthenium(I) Hexafluorophosphate. Formation
of the 1,10-phenanthroline analogue of [RuI2(PhCO2)(CO)4(bpy)2]-
(PF6), [RuI2(PhCO2)(CO)4(phen)2](PF6), was achieved by replace-
ment of 2,2′-bipyridine with 1,10-phenanthroline (174 mg, 0.88
mmol) in the reaction with [RuI(PhCO2)(CO)2(py)]2 (136 mg, 0.191
trans-Di-O,O-acetato-cis-di-C,C-carbonyl(5,5′-dimethyl-2,2′-
bipyridine)ruthenium(II). In an attempt to prepare [RuI2(MeCO2)-
(CO)4(5,5′-dmbpy)2]+, degassed methanol (25 mL) containing
[Ru(CO)2Cl2]n (320 mg, 1.4 mmol) and MeCO2Na (780 mg, 9.4
Inorganic Chemistry, Vol. 43, No. 2, 2004 689

Pearson et al.
Table 4. Crystal/Refinement Dataa
compoundb
formula
Ac
B
C
D
E
Fa
C18H18N2O6Ru‚
C18H18N2O6Ru
C19H12N2O4Ru‚H2O
C21H12N2O4Ru‚MeOH
C30H27N4O6Ru2PF6‚
C12H12N2
0.5CH2Cl2
1/3MeOH
Mr
501.9
459.4
451.4
489.5
897.4
184.2
cryst syst
space group
a/Å
b/Å
c/Å
monoclinic
C2/c (No. 15)
15.792(2)
17.579(3)
7.915(1)
triclinic
P1h (No. 2)
9.2447(8)
12.256(1)
16.403(1)
99.362(1)
98.224(1)
90.164(1)
1814
1.682
4
0.90
n/a
triclinic
P1h (No. 2)
8.001(2)
9.208(2)
12.673(3)
91.27(3)
107.50(3)
100.31(3)
873.2
1.717
2
0.93
n/a
monoclinic
P21/c (No. 14)
8.7171(2)
10.7983(2)
20.1286(6)
rhombohedral
R3hc (No. 167, hex.)
28.7660(3)
orthorhombic
(D2h15) (No. 51)
11.9978(6)
10.7508(8)
7.4927(9)
21.1130(3)
R/deg
â/deg
γ/deg
V/Å3
112.437(3)
97.110(3)
2031
1.641
4
0.94
0.74
1880
1.729
4
0.87
n/a
15 141
1.771
18
1.03
n/a
966.5
1.266
4
0.08
0.81
Dc/g cm-3
Z
µ
Mo/mm-1
“T”min/max
2θ min/deg
Nt
68
50
7969
5946 (0.050)
2370
0.056
55
56.6
60
75
17 549
4213 (0.097)
2580
0.052
0.048
1.6(4)
10 793
4102 (0.057)
3233
0.042
0.044
12 467
4624 (0.047)
3371
0.040
0.042
0.8(1)
9845
4925 (0.077)
3427
0.053
0.075
1.0(1)
20 080
2563 (0.042)
1743
0.045
0.052
0.57(9)
N (Rint
N0
)
R
Rw
0.053
1.0(1)
|∆F max|/e Å-3
1.2(1)
a Variations in procedures: (A) A solvent component was modeled as dichloromethane, disordered about a center of symmetry, site occupancy set at 0.5
after trial refinement. (B) Weak and limited data would support meaningful anisotropic displacement parameter refinement for Ru only. (C) A difference
map residue was modeled as a water molecule oxygen atom, associated hydrogen atoms also being credibly located. (D) Solvent residues were modeled in
terms of methanol, disordered over two sets of sites, occupancies refining to 0.707(6) and complement. (E) Solvent residues were modeled in terms of
methanol disordered about the 3h axis; the PF6 was modeled as disordered about an axis defined by a pair of opposed fluorines, site occupancies of the two
components refining to 0.62(2) and complement. b A is [RuII(MeCO2)2(CO)2(4,4′-dmbpy)]0.5CH2Cl2; B is [RuII(MeCO2)2(CO)2(5,5′-dmbpy)]; C is
[RuII(C6H4CO2)(CO)2(bpy)].H2O; D is [RuII(C6H4CO2)(CO)2(phen)].MeOH; E is [RuI2(MeCO2)(CO)4(5,5′-dmbpy)2](PF6); F is the 4,4′-dimethyl-2,2′-bipyridine
ligand. c Specimen sizes: 0.20 × 0.12 × 0.35 mm (A); 0.20 × 0.12 × 0.035 mm (B); 0.40 × 0.60 × 0.80 mm (C); 0.40 × 0.50 × 0.30 mm (D); 0.30 ×
0.20 × 0.18 mm (F).
mmol) was heated for 4 h at 120 °C under nitrogen before 5,5′-
dimethyl-2,2′-bipyridine (310 mg, 1.7 mmol) was added, and heat-
ing was continued for 15 min. The flask was then sealed and cooled
to 2 °C. A few orange crystals (of presumably [RuI2(MeCO2)(CO)4-
(5,5′-dmbpy)2](MeCO2/Cl)) and a larger amount of very pale yellow
crystals of trans-diacetato-cis-dicarbonyl(5,5′-dimethyl-2,2′-bi-
pyridine)ruthenium(II) ([RuII(MeCO2)2(CO)2(5,5′-dmbpy)]) pre-
cipitated overnight. (Yield: 0.14 g, 21%.) Anal. Calcd for
C18H18N2O6Ru {[RuII(MeCO2)2(CO)2(5,5′-dmbpy)]}: C, 47.1; H,
3.9; N, 6.1. Found: C, 46.8; H, 4.1; N, 6.2. Infrared spectrum (KBr
disk), cm-1: 2052 s, 1983 s, 1629 s, 1597 s, 1545 w, 1478 m,
1376 s, 1315 s, 1240 m, 1169 w, 1147 w, 1062 w, 1042 w, 1014
(bpy)] (yield: 104 mg, 31%) were washed with a little more CH2Cl2
(5 mL) and water (5 mL). Anal. Calcd for C19H14N2O5Ru
{[RuII(O2CC6H4)(CO)2(bpy)].H2O}: C, 50.6; H, 3.1; N, 6.2. Found:
C, 51.1; H, 3.0; N, 6.3. Infrared spectrum (KBr disk), cm-1: 2047
vs, 1962 vs, 1703 vw, 1630 s, 1599 s, 1580 s, 1494 w, 1474 w,
1444 m, 1324 s, 1246 w, 1182 w, 1142 m, 1073 vw, 1023 w, 852
w, 819 vw, 769 s, 740 s, 701 w, 643 w, 614 w, 560 vw, 519 w,
475 w, 455 w, 412 w. 1H NMR spectrum (d4-methanol): 7.18 (1H,
td, benz-H4), 7.42 (1H, td, benz-H5), 7.46 (1H, ddd, bpy-H5), 7.61
(1H, ddd, benz-H3), 7.77 (1H, ddd, benz-H6), 7.77 (1H, ddd, bpy-
H5′), 7.89 (1H, ddd, bpy-H6), 8.18 (1H, ddd, bpy-H4), 8.28 (1H,
ddd, bpy-H4′), 8.60 (2H, t*, sH3, H3′), 9.14 (1H, ddd, bpy-H6′).
13C NMR spectrum (d4-methanol): 124.9 (bpy-C3/C3′), 125.3
(benz-C4), 128.1 (bpy-C5), 128.8 (bpy-C5′), 131.1 (benz-C3),
133.8 (benz-C5), 139.6 (benz-C6), 141.1 (benz-C2), 141.3 (bpy-
C4), 141.9 (bpy-C4′), 151.5 (bpy-C6), 155.6 (bpy-C6′), 156.1 (bpy-
C2), 157.9 (bpy-C2′), 165.5 (benz-C1-Ru), 182.5 (CO2), 198.3
(CO), 199.5 (CO′). Electrospray mass spectrum (MeOH): m/z 435
(55%, [M + H]+), 457 (90%, [M + Na]+), 473 (50%, [M + K]+),
563 (10%, [M + I + 2H]+), 869 (30%, [2M + H]+), 891 (100%,
[2M + Na]+), 906 (30%, [2M + K]+).
µ-C,O-o-Phenylenecarboxylato-C,C-carbonyl(1,10-phenan-
throline)ruthenium(II). Sodium benzoate (1.05 g, 7.29 mmol),
[Ru(CO)2Cl2]n (175 mg, 0.767 mmol), and 1,10-phenanthroline (173
mg, 0.96 mmol) were heated in degassed methanol (25 mL), at a
bath temperature of 130 °C for 24 h as outlined for [RuII(MeCO2)2-
(CO)2(5,5′-dmbpy)]. The reaction mixture was filtered to remove
any impurities and then evaporated to dryness under vacuum. The
pale orange residue was suspended in CH2Cl2 and the solid sodium
benzoate was removed by filtration. The filtrate was evaporated to
give an orange solid which was dissolved in methanol and left in
the dark to evaporate giving a yellow powder of [RuII(O2CC6H4)-
(CO)2(phen)] (yield: 88 mg, 23%). Anal. Calcd for C22H16N2O5-
1
w, 839 m, 679 m. H NMR spectrum (d4-methanol): 1.78 (6H, s,
CH3CO2); 2.67 (6H, s, bpy-CH3); 8.21 (2H, d, H4,H4′); 8.55 (2H,
d, H3,H3′); 9.18 (2H, s, H6,H6′). Electrospray mass spectrum
(MeOH): m/z 401 (83%, [M - MeCO2]+), 483 (100%, [M +
Na]+), 943 (91%, [2M + Na]+).
µ-C,O-o-Phenylenecarboxylato-C,C-carbonyl(2,2′-bipyridine)-
ruthenium(II). Sodium benzoate (1.03 g, 7.15 mmol), [Ru(CO)2Cl2]n
(175 mg, 0.767 mmol), and 2,2′-bipyridine (175 mg, 1.12 mmol)
were heated in degassed methanol (25 mL), at a bath temperature
of 120 °C for 5 h, as outlined for [RuII(MeCO2)2(CO)2(5,5′-dmbpy)].
The reaction mixture was filtered to remove any impurities and
then evaporated to dryness. The residue was suspended in CH2Cl2
and the excess sodium benzoate extracted into water. The yellow
solution of CH2Cl2 was then left to evaporate, resulting in nearly
colorless diamond-shaped crystals in a bulk yellow oily substance.
Infrared spectrum of mixture (KBr disk), cm-1: 2047 s, 1962 s,
1749 w, 1704 w, 1600 s, 1494 w, 1474 w, 1444 m, 1324 ms, 1244
w, 1141 w, 1069 w, 1023 w, 850 w, 768 ms, 738 m, 645 w, 614
w, 519 w.
A small volume of CH2Cl2 was used to dissolve the yellow oil
leaving the crystals behind. The crystals, [RuII(O2CC6H4)(CO)2-
690 Inorganic Chemistry, Vol. 43, No. 2, 2004

Carbonyl-Carboxylato-Ruthenium Complexes
Ru {[RuII(O2CC6H4)(CO)2(phen)].MeOH}: C, 54.0; H, 3.3; N, 5.7.
merging to N unique (Rint cited), No with I > 2σ(I)/F > 4σ(F)
considered “observed” and used in the full-matrix least-squares
refinements (anisotropic displacement parameter forms for the non-
hydrogen atoms, (x, y, z, Uiso)H constrained at estimated values
(exception: 4,4′-dmbpy in which they were refined). Conventional
residuals R ()∑∆/∑Fo), Rw () (∑w∆2)/∑wFo2)1/2) (weights: (σ2(Fo)
+ 0.0003Fo2)-1/2) are cited at convergence. Neutral atom complex
scattering factors were employed, within the Xtal 3.7 program
system.30 Pertinent results are given in the tables and figures, the
latter showing 50% probability amplitude displacement envelopes
for the non-hydrogen atoms, hydrogen atoms having arbitrary radii
of 0.1 Å; see Supporting Information for full .cif depositions.
Individual variations in procedure are noted in footnote a of Table
4.
Found: C, 54.9; H, 3.4; N, 5.9. Infrared spectrum (KBr disk), cm-1
:
2038 s, 1962 s, 1747 w, 1703 m, 1620 s, 1575, 1425 m, 1402 m,
1342 w, 1314 m, 1258 w, 1142 w, 846 m, 718 m. 1H NMR
spectrum (d4-methanol): 7.24 (1H, td, 4JH4,H6 1.2, 3JH3,H4 ) 3JH4,H5
7.5 Hz, benz-H4), 7.48 (1H, td, benz-H5), 7.66 (1H, ddd, benz-
H3), 7.78 (1H, dd, phen-H3), 7.88 (1H, ddd, benz-H6), 8.10 (1H,
dd,3JH8,H9 5.0, 3JH7.H8 8.3 Hz, phen-H8), 8.18 (2H, q*, phen-H5,H6),
8.17 (1H, dd, phen-H2), 8.73 (1H, dd, phen-H4), 8.84 (1H, dd,
phen-H7), 9.51 (1H, dd, phen-H9). 13C NMR spectrum (d4-
methanol): 125.4 (benz-C4), 126.7 (phen-C3), 127.6 (phen-C8),
128.7 (phen-C5), 129.2 (phen-C6), 131.1 (benz-C3), 132.2 (phen-
C13), 132.3 (phen-C14), 133.8 (benz-C5), 139.7 (benz-C6), 140.3
(phen-C4), 141.0 (phen-C7), 141.2 (benz-C2), 147.0 (phen-C11),
148.4 (phen-C12), 152.0 (phen-C2), 155.9 (phen-C9), 165.3 (benz-
C1-Ru), 182.4 (benz-CO2), 198.4 (CO), 199.6 (CO′). Electrospray
mass spectrum (MeOH): m/z 459 (65%, [M + H]+), 481 (85%,
[M + Na]+), 497 (25%, [M + K]+), 917 (20%, [2M + H]+), 939
(100%, [2M + Na]+), 955 (10%, [2M + K]+).
Structure Determinations. Full spheres of CCD diffractom-
eter data were measured at low temperature (for 4,4′-dmbpy,
[Ru(MeCO2)2(CO)2(4,4′-dmbpy)], Bruker AXS instrument, T
ca. 153 K, “empirical”/multiscan absorption correction; for
[Ru(O2CC6H4)(CO)2(bpy)], a Bruker P4 instrument (ω-scans, T ca.
153 K); for the remainder, an Enraf-Nonius Kappa instrument (T
ca. 123 K), no absorption corrections; all structures, monochromatic
Mo KR radiation, λ ) 0.7107 Å). Nt(otal) reflections were obtained,
Acknowledgment. This research was supported by a
Monash University Research Grant.
Supporting Information Available: Crystallographic files for
the five X-ray structure determinations in CIF format, figures
showing unit cell projections, and text giving further details of 1H
NMR spectra including coupling constants. This material is
available free of charge via the Internet at http://pubs.acs.org.
IC0348401
(30) Hall, S. R.; du Boulay, D. J.; Olthof-Hazekamp, R. The Xtal 3.7 System;
Uniiversity of Western Australia: Perth, Australia, 2001.
Inorganic Chemistry, Vol. 43, No. 2, 2004 691