Group VIII coordination chemistry of a pincer-type bis(8-quinolinyl)amido ligand

Article abstract of DOI:10.1021/ic801047s

This paper provides an entry point to the coordination chemistry of the group VIII chemistry of the bis(8-quinolinyl)amine (BQA) ligand. In this context, mono- and disubstituted BQA complexes of iron, ruthenium, and osmium are described. For example, the low-spin bis-ligated Fe(III) complex [Fe(BQA)₂][BPh₄] has been prepared via amine addition to FeCl₃ in the presence of a base and NaBPh₄. Complexes featuring a single BQA ligand are more readily prepared for Ru and Os. Auxiliary ligands featuring a single BQA ligand, along with two other L-type donor ligands, allow for a variety of ligand types to occupy a sixth coordination site. Representative examples include the halide and pseudohalide complexes trans-(BQA)MX(PPh₃)₂ (M = Ru, Os; X = Cl, Br, N ₃, OTf), as well as the hydride and alkyl complexes trans-(BQA)RuH(PMe₃)₂ and trans-(BQA)RuMe(PMe ₃)₂. Electrochemical studies are discussed that help to contextualize the BQA ligand with respect to its neutral counterpart 2,2′,2″-terpyridine (terpy) in terms of electron-releasing character. Bidentate ligands have been explored in conjunction with the BQA ligand. Thus, the bidentate, monoanionic aryl(8-quinolinyl)amido ligand 3,5-(CF₃)₂-(C₆H₃)QA has been installed onto the (BQA)Ru platform to provide (BQA)Ru(3,5-(CF₃) ₂-(C₆H₃)QA)(PPh₃). A bis(phosphino)borate ligand stabilizes the five-coordinate complex [Ph ₂B(CH₂PPh₂)₂]Ru(BQA). Finally, access to dinitrogen complexes of the types [(BQA)Ru(N₂)(PPh ₃)₂][PF₆], [(BQA)Ru(N₂)(PMe ₃)₂][PF₆], and [(BQA)Os(N₂)(PPh ₃)₂][PF₆] is provided by exposure of the sixth coordination site under a N₂ atmosphere.

Full text of DOI:10.1021/ic801047s

Inorg. Chem. 2008, 47, 11570-11582
Group VIII Coordination Chemistry of a Pincer-Type
Bis(8-quinolinyl)amido Ligand
Theodore A. Betley,† Baixin A. Qian, and Jonas C. Peters*,‡
DiVision of Chemistry and Chemical Engineering, Arnold and Mabel Beckman Laboratories of
Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, and
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
Received June 11, 2008
This paper provides an entry point to the coordination chemistry of the group VIII chemistry of the
bis(8-quinolinyl)amine (BQA) ligand. In this context, mono- and disubstituted BQA complexes of iron, ruthenium,
and osmium are described. For example, the low-spin bis-ligated Fe(III) complex [Fe(BQA)2][BPh4] has been prepared
via amine addition to FeCl3 in the presence of a base and NaBPh4. Complexes featuring a single BQA ligand are
more readily prepared for Ru and Os. Auxiliary ligands featuring a single BQA ligand, along with two other L-type
donor ligands, allow for a variety of ligand types to occupy a sixth coordination site. Representative examples
include the halide and pseudohalide complexes trans-(BQA)MX(PPh3)2 (M ) Ru, Os; X ) Cl, Br, N3, OTf), as well
as the hydride and alkyl complexes trans-(BQA)RuH(PMe3)2 and trans-(BQA)RuMe(PMe3)2. Electrochemical studies
are discussed that help to contextualize the BQA ligand with respect to its neutral counterpart 2,2′,2′′-terpyridine
(terpy) in terms of electron-releasing character. Bidentate ligands have been explored in conjunction with the BQA
ligand. Thus, the bidentate, monoanionic aryl(8-quinolinyl)amido ligand 3,5-(CF3)2-(C6H3)QA has been installed
onto the (BQA)Ru platform to provide (BQA)Ru(3,5-(CF3)2-(C6H3)QA)(PPh3). A bis(phosphino)borate ligand stabilizes
the five-coordinate complex [Ph2B(CH2PPh2)2]Ru(BQA). Finally, access to dinitrogen complexes of the types
[(BQA)Ru(N2)(PPh3)2][PF6], [(BQA)Ru(N2)(PMe3)2][PF6], and [(BQA)Os(N2)(PPh3)2][PF6] is provided by exposure of
the sixth coordination site under a N2 atmosphere.
Introduction
cyclometalated arylbis(phosphine), and related systems where
the donors are amines, carbenes, and other donors are also
well established.2-4
In the past several years, “pincer-type” amido ligands have
gained prominence in organometallic and inorganic chem-
istry,5,6 the most popular examples of such systems being
diarylamido ligands in which two phosphine donors extend
Some years ago, the term “pincer-type amido” ligand was
introduced to refer to anionic tridentate ligands that feature
a central X-type metal-amido linkage with two chelating
donor arms extending from this central donor.1 The use of
the term “pincer” implied amido ligands that would most
commonly favor a planar binding geometry such that, when
coordinated to an octahedral metal complex, they would
display a mer binding configuration. In this regard, such
ligands are conceptually analogous to the more popular
family of anionic “pincer” ligands in which a central carbon
rather than nitrogen X-type linkage binds the metal. A
prototypical example of the latter ligand type is a
(2) (a) Pugh, D.; Danopoulos, A. A. Coord. Chem. ReV. 2007, 251, 610.
(b) van der Boom, M. E.; Milstein, D. Chem. ReV. 2003, 103, 1759.
(c) Gossage, R. A.; Van De Kuil, L. A.; van Koten, G. Acc. Chem.
Res. 1998, 31, 423.
(3) (a) Liu, F. C.; Pak, E. B.; Singh, B.; Jensen, C. M.; Goldman, A. S.
J. Am. Chem. Soc. 1999, 121, 4086. (b) Sundermann, A.; Uzan, O.;
Milstein, D.; Martin, J. M. L. J. Am. Chem. Soc. 2000, 122, 7095. (c)
Dani, P.; Karlen, T.; Gossage, R. A.; Gladiali, S.; van Koten, G.
Angew. Chem., Int. Ed. 2000, 39, 743.
(4) (a) Mayer, H. A.; Kaska, W. C. Chem. ReV. 1994, 94, 1239. (b)
Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Zanobini, F. Coord.
Chem. ReV. 1992, 120, 193. (c) Cotton, F. A.; Hong, B. Prog. Inorg.
Chem. 1992, 40, 179.
(5) Liang, L. C.; Lin, J. M.; Hung, C. H. Organometallics 2003, 22, 3007.
(6) Harkins, S. B.; Peters, J. C. J. Am. Chem. Soc. 2004, 126, 2885.
* Author to whom correspondence should be addressed. E-mail:
jcpeters@mit.edu.
†
Current address: Harvard University, Cambridge MA.
Current address: Massachusetts Institute of Technology, 77 Mas-
‡
sachusetts Ave Cambridge, MA 02139.
(1) Peters, J. C.; Harkins, S. B.; Brown, S. D. Inorg. Chem. 2001, 40,
5083.
11570 Inorganic Chemistry, Vol. 47, No. 24, 2008
10.1021/ic801047s CCC: $40.75  2008 American Chemical Society
Published on Web 11/13/2008

Group VIII Chemistry of a Bis(8-quinolinyl)amido Ligand
Scheme 1
from the ortho positions of the aryl rings.7 These ligands
closely resemble the hard/soft bis(phosphine)amido ligands
that were originally introduced by Fryzuk.8 Indeed, while it
is often assumed that the diarylamido bis(donor) ligands will
adopt a rigid planar geometry owing to the aryl bridging
units, such ligands are in fact conformationally quite flexible
and, like the earlier Fryzuk systems, give rise to more diverse
that have been studied in recent years,13 for example, in the
context of transfer dehydrogenation reactions.14 However,
in octahedral d6 complexes of the type described herein, a
filled amido N(2p) orbital is of appropriate symmetry to mix
with a filled metal d orbital (see Scheme 1). If significant
mixing occurs, the highest occupied molecular orbital
(HOMO) is raised in energy. This HOMO-raising can in
principle manifest itself at the metal complex by an increased
affinity for π-acidic ligands, or conversely, by a decreased
affinity for π-basic ligands.
9
structure types.
The pincer-type bis(8-quinolinyl)amido ligand, which
presents two sp2-hybridized hard N donors to a chelated metal
ion in addition to the diarylamido unit, is perhaps more highly
disposed to bind in a planar fashion; it was hence for this
ligand system that the term “pincer-type” amido ligand was
first coined.1 However, even this ligand can adopt a facial
binding motif, as shown for an octahedral Pt(IV) system.9c
Nevertheless, we and others have generally found that this
ligand is most typically disposed to a planar binding
motif1,9c,10,11 and is, moreover, a robust chelate even in the
presence of aqueous and acidic solvents. These properties
distinguish it from many other amido ligands, whether or
not they are stabilized by a chelate effect, for which
aminolysis can be both kinetically and thermodynamically
problematic. In this regard, bis(8-quinolinyl)amido ligands
have many properties in common with conjugated aromatic
N-heterocyclic chelates, such as the ubiquitous 2,2′,2′′-
terpyridine (terpy) ligand,12 and should likewise be robust
under relatively oxidizing conditions owing to the exclusive
presence of hard N donors conjugated into an aromatic π
system. However, as the bis(8-quinolinyl)amine (BQA)
ligand is typically monoanionic when coordinated to a metal,
rather than a neutral donor as for terpy, its resulting metal
complexes should be appreciably more electron-rich than
terpy relatives, a property that is potentially advantageous
for reductive small molecule activation reactions.
Results and Discussion
Preparation of [Fe(BQA)2][BPh4]. To obtain electro-
chemical data of M(BQA)2 species for comparison with
ferrocene, we sought to prepare Fe(BQA)2. We have pre-
viously found that delivery of the bis(quinolinyl)amine
(HBQA, 1) ligand to group 10 metals could be achieved via
two routes: reaction of a metal halide with 1[Li] or reaction
of the free amine 1 with a metal precursor in the presence
of excess base.1 Metalation of the BQA ligand was carried
out with FeCl3 (anhydrous) via an in situ salt metathesis
reaction (eq 1). Reacting two equivalents of amine 1 with
FeCl3 in dichloromethane with the addition of Na2CO3 in
water results in rapid formation of the desired complex
[Fe(BQA)2][Cl]. The addition of an aqueous solution of
(7) Liang, L. C. Coord. Chem. ReV. 2006, 250, 1152.
(8) Fryzuk, M. D. Can. J. Chem. 1992, 70, 2839.
(9) (a) Harkins, S. B.; Peters, J. C. J. Am. Chem. Soc. 2004, 126, 2885.
(b) Harkins, S. B.; Peters, J. C. J. Am. Chem. Soc. 2005, 127, 2030.
(c) Harkins, S. B.; Peters, J. C. Inorg. Chem. 2006, 45, 4316. (d) Fout,
A. R.; Basuli, F.; Fan, H. J.; Tomaszewski, J.; Huffman, J. C.; Baik,
M. H.; Mindiola, D. J. Angew. Chem., Int. Ed. 2006, 45, 3291.
(10) (a) Jenson, K. A.; Nielson, P. H. Acta Chem. Scand. 1964, 18, 1. (b)
Puzas, J. P.; Nakon, R.; Pertersen, J. L. Inorg. Chem. 1986, 25, 3837.
(11) Maiti, D.; Paul, H.; Chanda, N.; Chakraborty, S.; Mondal, B.; Puranik,
V. G.; Lahiri, G. K. Polyhedron 2004, 831.
(12) Sauvage, J.-P.; Collin, J.-P.; Chambron, J.-C.; Guillerez, S.; Coudret,
C.; Balzani, V.; Barigelletti, F.; De Cola, L.; Flamigni, L. Chem. ReV.
1994, 94, 993.
(13) (a) Gusev, D. G.; Madott, M.; Dolgushin, F. M.; Lyssenko, K. A.;
Antipin, M. Y Organometallics 2000, 19, 1734. (b) Regis, R. M.;
Rozenberg, H.; Shimon, L. J. W.; Milstein, D. Organometallics 2001,
20, 1719. (c) Dani, P.; Karlen, T.; Gossage, R. A.; Smeets, W. J. J.;
Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 1997, 119, 11317. (d)
Jia, G.; Lee, H. M.; Xia, H. P.; Williams, I. D. Organometallics 1996,
15, 5453.
To begin to more thoroughly explore the advantages and
disadvantages of the bis(8-quinolinyl)amido auxiliary as a
conveniently synthesized, monanionic “pincer” analogue of
terpyridine, we have undertaken the preparation and study
of a series of group VIII coordination complexes supported
by BQA. These systems are cousins of tridentate and planar
2,6-bis(phosphino)aryl-Ru(II) (i.e., PCP-Ru(II)) complexes
(14) Dani, P.; Karlen, T.; Gossage, R. A.; Gladiali, S.; van Koten, G. Angew.
Chem., Int. Ed. 2000, 39, 743.
Inorganic Chemistry, Vol. 47, No. 24, 2008 11571

Betley et al.
Figure 1. (a) Electronic spectrum of [Fe(BQA)2][BPh4] (2). (b) EPR spectrum of solid 2 (4 K, X-band, 9.62 GHz).
Figure 2. Displacement ellipsoid representation (50%) of (a) (BQA)RuCl(cod) (3), (b) (BQA)RuCl(PPh3)2 (5), and (c) (BQA)OsCl(PPh3)2 (6). Hydrogen
atoms have been removed for clarity. Selected bond distances (Å) and angles (deg) for 3: Ru-N1 2.128(3), Ru-N2 2.048(2), Ru-N3 2.126(3), Ru-Cl
2.426(1), avg. Ru-C 2.215(3), N1-Ru-N2 76.9(1), N2-Ru-N3 77.9(1), N1-Ru-N3 151.5(1). For 5: Ru-N1 2.066(3), Ru-N2 2.005(2), Ru-N3 2.061(3),
Ru-Cl 2.482(1), Ru-P1 2.397(1), Ru-P2 2.379(1), N1-Ru-N2 80.4(1), N2-Ru-N3 80.3(1), N1-Ru-N3 160.7(1), P1-Ru-P2 178.9(1). For 6: Os-N1
2.063(3), Os-N2 2.023(3), Os-N3 2.064(3), Os-Cl 2.488(1), Os-P1 2.368(1), Os-P2 2.381(1), N1-Os-N2 81.5(1), N2-Os-N3 80.1(1), N1-Os-N3
161.5(1), P1-Os-P2 174.8(1).
NaBPh4 to the reaction affords [Fe(BQA)2][BPh4] (2). The
resulting brick red, cationic FeIII species is air-stable and is
readily soluble in polar solvents (CH2Cl2, DMSO). This is
distinct from its poorly soluble iron(II) counterpart, Fe-
(BQA)2, which can be readily generated from FeCl2, HBQA,
and NEt3 (or from 1[Li] and FeCl2) and identified by
electrospray ionization mass spectrometry, but is difficult to
isolate in pure form owing to its poor solubility. Complex 2
intense transitions at 514, 418, and 306 nm are most likely
ligand-centered π-π* transitions, which is in agreement with
the recently assigned spectrum for [Co(BQA)2][ClO4] by
Lahiri et al.11 The presence of a weak transition at 680 nm
2
may be the d-d transition (3A1 f Tg) expected for the d5
system. The large extinction coefficient for the band at 1030
nm suggests it is a charge-transfer band, quite possibly a
ligand-to-metal charge transfer event in which a ligand-
centered electron is excited into the singly occupied d orbital.
The EPR of a solid sample of 2 was also collected at 4 K
and is shown in Figure 1b. The spin S ) 1/2 state of 2 gives
rise to a rhombic signal where the three g tensors are
resolved: gz ) 2.39, gy ) 2.14, gx ) 1.98. No hyperfine
coupling to nitrogen is observed.
1
exhibits paramagnetically shifted H NMR resonances and
appears to populate a doublet ground state exclusively (µeff
) 2.1 µB), as determined by a room-temperature-solution
Evans method determination.15 Iron(III) {Fe(terpy)2}+ spe-
cies are likewise low-spin in nature.16
Preparation of Ru and Os BQA Complexes. A single
BQA ligand can be installed onto divalent Ru or Os centers
from a variety of precursors. For example, the reaction of
polymeric [RuCl2(COD)]n with one equivalent of 1[Li] yields
(BQA)RuCl(COD) (3) and variable amounts (20-30%) of
the disubstituted species Ru(BQA)2 (COD ) cyclooctadiene).
Flash chromatography effectively separates the products.
Complex 3 has been characterized in the solid state by X-ray
crystallography, and its solid-state structure is shown in
Figure 2. Quantitative conversion to the disubstituted species
Ru(BQA)2 (4) can be achieved by refluxing [RuCl2(COD)]n
with two equivalents of 1[Li] in toluene. An electrospray
mass spectrum (ES-MS) of the product mixture reveals only
the parent ion peak for the disubstituted species, 4, at m/z )
A dichloromethane solution of 2 exhibits multiple intense
transitions in the UV-visible region, [λmax/nm (ε/M-1 cm-1)]:
1030 (11 000), 680 (2700), 514 (33 000), 418 (49 000), 306
(90 000) (Figure 1a). The high extinction coefficients for the
(15) (a) Sur, S. K. J. Magn. Reson. 1989, 82, 169. (b) Evans, D. F. J. Chem.
Soc. 1959, 2003.
(16) Reiff, W. M. J. Am. Chem. Soc. 1974, 96, 3829.
11572 Inorganic Chemistry, Vol. 47, No. 24, 2008

Group VIII Chemistry of a Bis(8-quinolinyl)amido Ligand
Figure 3. (a) Cyclic voltammetry of 2 in 0.4 M nBu4NPF6/THF, scan rate ) 75 mV/s. (b) Postulated radical delocalization of the bis(quinolinyl)amide
ligand (Q ) quinoline).
642, without 3 or any ligand fragmentation products apparent
in the spectrum.
) +0.14 V. The shape of the secondary oxidation event was
independent of scan rate (0.05-0.5 V/s) and did not change
noticeably when THF or dichloromethane was the solvent.
This second redox event could signify a FeIV/III redox event,
or it could represent some redox process centered on the
BQA ligand itself. The BQA ligand, which exhibits an
irreversible oxidation event at +0.56 V (vs Fc/Fc+), is the
most likely the candidate for oxidation in this case. If this
second redox event is ligand-centered, the radical thus formed
can be delocalized over the quinoline rings of BQA. Possible
contributing resonance structures that would serve to stabilize
the radical are presented in Figure 3b. In any event, the
increase in current that is observed positive in this event (ca.
0.3V) suggests the formation of at least one new species from
the irreversible redox process.
Refluxing RuCl2(PPh3)3 in dichloromethane with HBQA
in the presence of excess base (NEt3) results in the formation
of (BQA)RuCl(PPh3)2 (5), which can be isolated in crystal-
line yields exceeding 85%. The 31P NMR spectrum of 5
shows a single chemical shift at δ ) 29 ppm in benzene,
suggesting that the phosphorus nuclei are trans-disposed with
the BQA ligand bound in the expected mer fashion. This is
confirmed by X-ray diffraction (XRD) analysis (vide infra).
Product 5 can also be obtained via salt elimination by the
reaction of 1[Li] and RuCl2(PPh3)3 in toluene at room
temperature. Similarly, the Os congener (BQA)OsCl(PPh3)2
(6) is produced via the reaction of 1[Li] and OsCl2(PPh3)3
in toluene at room temperature. However, when OsCl2(PPh3)3
is exposed to the free amine 1, in the presence of excess
triethylamine base, the product cis-(PPh3)2OsCl(BQA) (7)
is instead exclusively obtained, as revealed by its 31P NMR
Ruthenium complexes bearing the BQA ligand and 2,2′,2′′-
terpyridine (terpy) ligands were also examined to compare
the BQA ligand’s electron releasing character with its neutral
terdentate counterpart. Thus, [Ru(terpy)2]2+ (8),18 [(terpy)Ru
(BQA)][BPh4] (9), and Ru(BQA)2 (4) were each studied by
cyclic voltammetry. The mixed BQA/terpy complex 9 was
readily synthesized by refluxing a dichloromethane solution
of (terpy)RuCl2(PPh3)19 with one equivalent of NaBPh4 and
1 in the presence of three equivalents of triethylamine. The
cyclic voltammograms for 8, 9, and 4 are presented in Figure
2
spectrum (δ 2.2, -0.9, JP-P ) 10.7 Hz). While 7 can be
isolated as a brown solid, all attempts to crystallize it from
solution invariably yielded crystals of the green, trans-
disposed product 6, suggesting the latter to be thermally
favored on steric grounds. The solid-state crystal structures
for complexes 5 and 6 are shown in Figure 2. The solid-
state structures for 3, 5, and 6 all demonstrate that the BQA
ligand binds in a mer fashion. The amido N-M bond
distances are consistently shorter (∆ ∼ 0.06 Å) than the
quinolinyl N-M bond distances. The proclivity for the BQA
ligand to “pinch” back is also apparent by the N1-M-N3
bond angles, which range from 150 to 160°. Finally, the BQA
ligands display a gentle twist that presumably relieves a steric
interaction between the H atoms connected to the C7
positions of the two quinoline arms.
Electrochemical Analysis of (BQA)nM Complexes. It
is interesting to compare the FeIII/II redox potentials of 2 to
other examples of homoleptic Fe complexes. Figure 3 shows
the cyclic voltammogram of 2 in 0.1 M nBu4NPF6 in
dichloromethane referenced against an internal Fc/Fc+
standard. The FeIII/II couple for 2 (E1/2 ) -0.79 V, ∆p ) 65
mV) is 0.79 V more reducing than the FeIII/II couple for Fc,
suggesting that 2 could be used as a mild oxidizing agent.17
The electron-rich Fe(BQA)2 system features an FeIII/II couple
that is at a potential even lower than Cp*2Fe, which exhibits
an FeIII/II couple at -0.48 V.17 In addition to the FeIII/II couple,
complex 2 exhibits a second, irreversible redox event at E1/2
n
4a. The measurements were taken in 0.1 M Bu4NPF6 in
dichloromethane and referenced against an internal Fc/Fc+
standard. Complexes 8, 9, and 4 (labeled A, B, and C in
Figure 4a, respectively) each exhibit reversible waves
assigned as RuIII/II couples. The effect of substituting the
neutral terpy ligand by anionic BQA is dramatic. The RuIII/
II couple shifts cathodically by ca. 620 mV from the dication
8 (E1/2 ) 0.92 V)18 to the monocation 9 (E1/2 ) 0.31 V, ∆p
) 89 mV); the RuIII/II couple shifts an additional 520 mV
from 9 to neutral 4 (E1/2 ) -0.21 V, ∆p ) 99 mV). As for
the iron derivative 2, neutral 4 exhibits a second wave
centered at E1/2 ) +0.60 V (∆p ) 97 mV), though in this
case, it exhibits a higher degree of reversibility. There is
also a small feature, centered at ca. 0.3 V, that is most likely
due to an impurity in the sample. As discussed above, the
higher potential redox event may be attributable to a
reversible RuIV/III couple, or it may represent a redox event
(18) Sauvage, J.-P.; Collin, J.-P.; Chambron, J.-C.; Guillerez, S.; Coudret,
C.; Balzani, V.; Barigelletti, F.; De Cola, L.; Flamigni, L. Chem. ReV.
1994, 94, 993.
(19) Sullivan, B. P.; Calvert, J. M.; Meyer, T. J. Inorg. Chem. 1980, 19,
1404.
(17) Connelly, N. G.; Geiger, W. E. Chem. ReV. 1996, 96, 877.
Inorganic Chemistry, Vol. 47, No. 24, 2008 11573

Betley et al.
n
Figure 4. (a) Cyclic voltammetry of [(terpy)2Ru]2+ (8), [(terpy)Ru(BQA)]+ (9), and Ru(BQA)2 (4), in 0.4 M Bu4NPF6/CH2Cl2, scan rate ) 75 mV/s. (b)
n
Cyclic voltammetry of (D) (BQA)RuCl(PPh3)2 (5) and (E) (BQA)OsCl(PPh3)2 (6), in 0.1 M Bu4NPF6/CH2Cl2, scan rate ) 50 mV/s.
Scheme 2
at the BQA ligand. At present, we cannot distinguish between
these two possibilities, though it is noteworthy that the second
redox wave is observed at significantly different potentials
for the two M(BQA)2 species (M ) Fe, Ru).
Ligand Exchange Reactions. To survey the general
reactivity of the (BQA)MX(PPh3)2 complexes, we probed
exchange reactions of the phosphine and halide ligands
(Scheme 2). Substitution of the PPh3 units on 5 for smaller,
stronger σ-donor phosphine ligands occurs under relatively
mild conditions. For example, triethylphosphine fully sub-
stitutes in refluxing toluene to form trans-(BQA)RuCl(PEt3)2
(10), while trimethylphosphine fully substitutes at room
temperature to form trans-(BQA)RuCl(PMe3)2 (11) (Scheme
The potential MIV/III redox couples observed for 2 and 4
prompted us to examine whether this feature was limited to
complexes of the composition M(BQA)2. Interestingly, both
the ruthenium and osmium complexes, 5 and 6, also exhibit
two reversible redox processes, as shown in Figure 4b (0.4
M nBu4NPF6 in dichloromethane, referenced to internal Fc/
2). The trans geometry is preserved as evidenced by the 31
P
Fc+). Complex 5 exhibits a reversible redox wave at E1/2
)
NMR spectrum, which shows a single chemical shift for both
10 and 11 at 11.8 and 0.5 ppm, respectively. Refluxing 5 in
excess pyridine resulted in incomplete phosphine substitution,
as ascertained by 31P NMR, while acetonitrile did not effect
any phosphine displacement under refluxing conditions.
Likewise, refluxing precursor 5 with larger ligand types such
as PCy3 failed to afford phosphine displacement.
-0.55 V (∆p ) 78 mV) assigned as the RuIII/II couple. The
second reversible redox wave occurs at E1/2 ) +0.45 V (∆p
) 76 mV). The Os complex 6 similarly displays two
reversible redox processes centered at E1/2 ) -0.72 V (OsIII/
II, ∆p ) 85 mV) and E1/2 ) +0.23 V (BQA/BQA+, ∆p ) 83
mV).
11574 Inorganic Chemistry, Vol. 47, No. 24, 2008

Group VIII Chemistry of a Bis(8-quinolinyl)amido Ligand
Figure 5. Displacement ellipsoid representation (50%) of (left) (BQA)Ru(3,5-(CF3)2-(C6H3)QA)(PPh3) (19) and (right) [(Ph2BP2)RuCl(BQA)][NEt4] (21).
Hydrogen atoms and solvent molecules have been removed for clarity. Selected bond distances (Å) and angles (deg) for 19: Ru-N1 2.066(3), Ru-N2
2.021(3), Ru-N3 2.045(3), Ru-N4 2.094(3), Ru-N5 2.144(3), Ru-P1 2.319(1), N1-Ru-N2 81.02(1), N2-Ru-N3 80.88(1), N1-Ru-N3 160.82(1),
N4-Ru-N5 77.48(1), N5-Ru-P1 170.99(1). For 21: Ru-N1 2.095(4), Ru-N2 2.050(4), Ru-N3 2.078(4), Ru-Cl 2.515(1), Ru-P1 2.353(1), Ru-P2
2.291(1), N1-Ru-N2 78.9(1), N2-Ru-N3 79.8(1), N1-Ru-N3 158.1(1), P1-Ru-P2 90.33(5).
Scheme 3
We also probed the replacement of the halide ligand in
11 with several other anionic ligands. For instance, refluxing
11 in THF with four equivalents of potassium halide salts
produced the bromide and iodide complexes trans-(BQA)Ru-
Br(PMe3)2 (12) and trans-(BQA)RuI(PMe3)2 (13) (Scheme
2). The reaction between 11 and LiAlH4 in toluene at room
temperature provided the hydride complex trans-(BQA)Ru-
H(PMe3)2 (14) in moderate yield. Access to the methyl
complex trans-(BQA)RuMe(PMe3)2 (15) required excess
MeLi in refluxing toluene. The azide complex trans-
(BQA)Ru(N3)(PMe3)2 (16) was readily prepared by refluxing
NaN3 and 11 in a mixture of THF and dichloromethane for
several hours. Complexes 12-16 all maintain the coordina-
tion environment of the parent species 11, showing no
propensity to give rise to other isomers. For the methyl and
hydride derivatives in particular, it is noteworthy that the
amido N atom and the alkyl/hydride ligand remain trans-
disposed. This contrasts with PCP-type pincer systems, where
cis disposition is often favored.20 We presume that the amido
N atom of the BQA system is not very strongly trans
influencing, and that the phosphine ligands themselves are
appreciably more so.
We also canvassed the reaction between 5 and the sodium
salt of the bidentate monoquinolinyl-amide ligand [3,5-(CF3)2-
(C6H3)QA][Na(Et2O)] (18), because we were interested in
determining whether the two amide functionalities would adopt
a cis or trans arrangement. This reaction produced the deep
purple complex (BQA)Ru(3,5-(CF3)2-(C6H3)QA)(PPh3) (19)
(Scheme 3). For 19, the amide from the monoquinoline ligand
adopts a trans disposition to the phosphine ligand, orienting the
bulky bis-3,5-triflouromethyl phenyl amide substituent on the
opposite side of the BQA plane from the phosphine ligand. This
orientation was verified via crystallographic characterization of
19, whose solid-state structure is shown in Figure 5, and can
likely be explained on steric grounds alone. Interestingly, the
monoquinolinyl amido N atom that is trans to the phosphine
ligand (N5 in Figure 5) is substantially elongated relative to
the amido N atom from the BQA ligand (N2 in Figure 5) due
to the strong trans influence of the phosphine ligand. Substitution
of the remaining phosphine ligand of 19 occurs when it was
refluxed in toluene. For example, the carbonyl adduct (BQA-
)Ru(3,5-(CF3)2-(C6H3)QA)(CO) (20) is formed by refluxing 19
in toluene under an atmosphere of CO gas for 20 h. Formation
of 20 from 19 is accompanied by a color change from deep
purple to an intense red.
(20) (a) Vila, J. M.; Pereira, M. T.; Ortigueira, J. M.; Lata, D.; Lopez Torres,
M.; Fernandez, J. J.; Fernandez, A.; Adams, H. J. Organomet. Chem.
1998, 566, 93. (b) Crespo, M.; Solans, X.; Font-Bardia, M. Polyhedron
1998, 17, 3927. (c) Gandelman Vigalok, A.; Shimon, L. J. W.;
Milstein, D. Organometallics 1997, 16, 3981.
Inorganic Chemistry, Vol. 47, No. 24, 2008 11575

Betley et al.
Scheme 4
Scheme 5
The reaction of 5 with the anionic bis(phosphine) ligand
of dinitrogen, even under elevated pressures (60-80 psi).
This was somewhat surprising to us, especially in light of
observations regarding N2 binding described below. The
carbonyl complex [Ph2BP2]Ru(CO)(BQA) (23) can be readily
prepared, however, by the addition of CO gas to a solution
of 22 in dichloromethane, or alternatively, by chloride
displacement in 21 in THF.
Cationic (BQA)M(PR3)2(L)+ Species (M ) Ru, Os).
Halide abstraction routes were also canvassed so as to expose
a labile coordination site at the (BQA)M(PR3)2(X) species.
Chloride abstraction reactions with 5 or 6 using sodium or
potassium reagents such as NaBPh4 or KPF6 proceeded only
in the presence of relatively good donor solvents. For
instance, the reaction of trans-(BQA)RuCl(PPh3)2 (5) with
NaBPh4 in a mixture of THF/acetonitrile immediately
produced the purple solvento species [(BQA)Ru(NCCH3)
(PPh3)2][BPh4] (24) with a concomitant release of NaCl
(Scheme 5). By contrast, complex 5 is not reactive toward
an excess of NaBPh4 under a dinitrogen atmosphere over a
period of several days, even when pressurized with N2
(14-80 psi of N2). This was true in a variety of solvents
[Ph2B(CH2PPh2)2][NEt4] (hereafter referred to as [Ph2BP2])21
in THF generated the product {[Ph2BP2]RuCl(BQA)}{NEt4}
(21) as a midnight blue solid. The 31P NMR spectrum for
complex 21 displays a doublet of doublets (δ 54, 28.3 ppm,
2JP-P ) 36 Hz), indicating the inequivalent phosphorus
environments. This is confirmed by the solid-state X-ray
crystal structure (Figure 5). The [Ph2BP2]- ligand afforded
complete displacement of the phosphine ligands from 5.
Interestingly, the chloride remains coordinated to the metal
in a position cis to the amido nitrogen. Washing 21 with
ethanol, however, extracts NEt4Cl to precipitate the 16-
electron, neutral complex [Ph2BP2]Ru(BQA) (22) as a wine
red solid (Scheme 4). Complex 22 displays a singlet in its
31P NMR spectrum at 69 ppm, which suggests that the
phosphine positions are equivalent on the NMR time scale,
and we presume 22 adopts the trigonal-bipyramidal geometry
shown in Scheme 4, though no solid-state structural data are
available. The neutral complex 22 is stable as a coordina-
tively unsaturated complex and does not bind an equivalent
(21) Thomas, J. C.; Peters, J. C. J. Am. Chem. Soc. 2001, 123, 5100.
11576 Inorganic Chemistry, Vol. 47, No. 24, 2008

Group VIII Chemistry of a Bis(8-quinolinyl)amido Ligand
Scheme 6
(e.g., THF, THF/EtOH, CH2Cl2). The reaction of 5 with
NaBPh4 under an atmosphere of carbon monoxide in THF
produces the cherry red complex [(BQA)Ru(CO)(PPh3)2]
[BPh4] (25) within minutes (Scheme 5). The Os congener
[(BQA)Os(CO)(PPh3)2][BPh4] (26) can be similarly synthe-
sized from 6 and NaBPh4. For both 25 and 26, the phosphines
remain trans-disposed, as indicated by their 31P NMR spectra,
which show single peaks for both species (δ ) 30.1 ppm
for 25, 0.31 ppm for 26). The infrared stretching frequency
of the carbonyl ligand for cationic 25 (νCO ) 1946 cm-1) is
lower than that of the neutral terpyridine complex
(trpy)RuCl2(CO) (νCO ) 1953 cm-1).19 The Os complex 26
features a more substantially reduced carbonyl stretching
frequency (νCO ) 1921 cm-1) from 25.
In an effort to realize Ru(BQA) systems that might bind
dinitrogen, more aggressive halide scavenging reagents were
canvassed. Puenta and co-workers successfully employed
AgOTf as a halide scavenger to form a cationic dinitrogen
complex en route to [TpRu(N2)(PEt3)2][BPh4] (Tp ) hydro-
tris(pyrazolyl)borate),22 and van Koten et al. have reported
that the PCP-pincer complex [RuII(OTf){C6H2(CH2-
PPh2)2}(PPh3)] can be prepared by the addition of AgOTf
to the corresponding chloride precursor.23 However, when
a solution of 5 in THF protected from ambient room light is
exposed to an equimolar amount of AgOTf, the initially aqua-
blue hue of 5 immediately fades along with the production
of a dark brown precipitate and Ag0 mirror. The isolated
brown solid is assigned as the paramagnetic oxidation
product [(BQA)RuIIICl(PPh3)2][OTf] (27) (Scheme 5).
To circumvent a metal oxidation event, thallium reagents
were employed. The divalent triflate complexes (BQA)Ru-
(OTf)(PPh3)2 (28) and (BQA)Os(OTf)(PPh3)2 (29) thus
proved available by reaction between the corresponding
chloride complexes 5 and 6 and TlOTf in THF (Scheme 6).
These complexes are difficult to isolate in analytically pure
form, presumably due to the high lability of the triflate ligand
and propensity to coordinate solvent or dinitrogen. Thus,
when 5 is stirred with TlPF6 in THF solution, the color of
the solution darkens within minutes to produce a midnight
blue solution along with concurrent release of a white
precipitate. A 31P NMR spectrum of this solution, taken in
situ, shows a very modest shift from 5 (δ ) 29 ppm) to 28
ppm, whereas the solution IR does not reveal any vibrations
unique from the parent species 5. We therefore conclude
that this species is the THF solvent adduct
[(BQA)Ru(THF)(PPh3)2][PF6]. Removal of the reaction vola-
tiles in vacuo yields a purple solid that has limited solubility
in THF and is completely insoluble in hydrocarbon solvents
(e.g., pentane, benzene, toluene). Dissolution of this purple
residue in dichloromethane affords an intense cherry-red
solution (λmax ) 542 nm), and examination of its IR spectrum
reveals an intense vibration at 2130 cm-1 attributable to a
coordinated dinitrogen ligand. The product is thus assigned
as trans-[(BQA)Ru(N2)(PPh3)2][PF6] (30). Complex 30 shows
a single 31P NMR resonance at 25 ppm, confirming that the
phosphines remain trans-disposed. The THF adduct complex
has not been more thoroughly characterized due to its
propensity to form 30 upon storage under N2 atmospheres.
Thallium halide abstraction from the more electron-rich
PMe3 complex 11 with TlPF6 proceeds directly to the
dinitrogen adduct complex [(BQA)Ru(N2)(PMe3)2][PF6] (31)
in THF solutions (KBr/THF; νNN ) 2129 cm-1), without
(22) Tenorio, M. A. J.; Tenorio, M. J.; Puerta, M. C.; Valerga, P. J. Chem.
Soc., Dalton Trans. 1998, 3601.
(23) Karlen, T.; Dani, P.; Grove, D. M.; Steenwinkel, P.; van Koten, G.
Organometallics 1996, 15, 5687.
Inorganic Chemistry, Vol. 47, No. 24, 2008 11577

Betley et al.
Experimental Section
All manipulations were carried out using standard Schlenk or
glovebox techniques under a dinitrogen atmosphere. Unless oth-
erwise noted, solvents were deoxygenated and dried by thorough
sparging with N2 gas followed by passage through an activated
alumina column. Nonhalogenated solvents were typically tested with
a standard purple solution of sodium benzophenone ketyl in
tetrahydrofuran in order to confirm effective oxygen and moisture
removal. The reagents NaBPh4, TlPF6, FeCl2, and FeCl3(anhydrous)
were purchased from commercial vendors and used without further
purification. HBQA (1, HBQA
)
bis(quinolinyl)amide),1
RuCl2(PPh3)3,25 [RuCl2(cod)]n,26 OsCl2(PPh3)3,27 and [Ph2B(CH2-
PPh2)2][NEt4]21 were synthesized as described previously. Deuter-
ated solvents were degassed and stored over activated 3 Å molecular
sieves prior to use. Elemental analyses were carried out at Desert
Analytics, Tucson, Arizona. NMR spectra were recorded at ambient
temperature on Varian Mercury 300 MHz, Joel 400 MHz, and
Figure 6. Displacement ellipsoid representation (50%) of
[(BQA)Os(N2)(PPh3)2][PF6] (32). Hydrogen atoms have been removed for
clarity. Selected bond distances (Å) and angles (deg) for 32: Os-N1
2.096(2), Os-N2 2.032(3), Os-N3 2.062(2), Os-N4 1.954(3), N4-N5
1.080(4), Os-P1 2.403(1), Os-P2 2.403(1), N1-Os-N2 79.97(1),
N2-Os-N3 80.80(1), N1-Os-N3 160.6(1), P1-Os-P2 177.4(1).
1
Anova 500 MHz spectrometers, unless otherwise noted. H and
13C NMR chemical shifts were referenced to residual solvent. 31P
NMR, 11B NMR, and 19F NMR chemical shifts are reported relative
to an external standard of 85% H3PO4, neat BF3 ·Et2O, and neat
CFCl3, respectively. IR spectra were recorded on a Bio-Rad
Excalibur FTS 3000 spectrometer controlled by Win-IR Pro
software. MS data for samples were obtained by injection of a
hydrocarbon solution into a Hewlett-Packard 1100MSD Mass
Spectrometer (ES+) or an Agilent 5973 Mass Selective Detector
(EI). UV-vis measurements were taken on a Hewlett-Packard
8452A diode array spectrometer using a quartz crystal cell with a
Teflon cap. X-ray diffraction studies were carried out in the
Beckman Institute Crystallographic Facility on a Bruker Smart 1000
CCD diffractometer.
X-Ray Crystallography Procedures. X-ray-quality crystals
were grown as indicated in the experimental procedures for each
complex. The crystals were mounted on a glass fiber with
Paratone-N oil. Structures were determined using direct methods
with standard Fourier techniques using the Bruker AXS software
package. In some cases, Patterson maps were used in place of the
direct methods procedure.
discernible formation of a THF solvent adduct species.
Likewise, reaction of the Os complex 6 with TlPF6 produces
the dinitrogen adduct [(BQA)Os(N2)(PPh3)2][PF6] (32) with-
out an observable THF solvent adduct precursor (see Scheme
6). The Os congener 32 is appreciably more stable than its
ruthenium cousins and is identifiable as the Os-N2 cation
by ES-MS (m/z ) 1014) and IR spectroscopy (νNN ) 2073
cm-1). A solid-state crystal structure of this latter species
was obtained via XRD analysis, further confirming that the
N2 ligand resides at the site trans to the amido nitrogen
(Figure 6). The dinitrogen ligand does not exhibit significant
elongation from free N2.24
Conclusions
The bis(quinolinyl)amido ligand featured in this manu-
script can be exploited as an anionic analogue of the
ubiquitous, neutral polypyridine ligand 2,2′,2′′-terpyridine
(terpy). The family of Ru and Os complexes described herein
underscores this point. Comparative electrochemical studies
establish that the bis(quinolinyl)amido ligand substantially
shifts MIII/II and MIV/III redox couples cathodically relative
to structurally related terpy derivatives. We caution that the
degree to which the BQA ligand can behave as a redox
noninnocent ligand has yet to be firmly established. Hence
ligand-centered oxidation cannot be ruled out at positive
potentials. Regardless, the (BQA)MII(L)2 platform (M ) Ru,
Os) gives rise to a wealth of well-defined substitution
chemistry providing access to a structurally diverse set of
complexes. Opportunities for small molecule activation
chemistry within these systems are envisaged. The N2 adducts
characterized herein suggest that favorable π-donation from
the BQA ligand will facilitate binding of π-acidic substrates
at the site trans to the N-amido donor. Future studies will
aim to explore the reactivity patterns of the systems described
herein.
EPR Measurements. X-band EPR spectra were obtained on a
Bruker EMX spectrometer equipped with a rectangular cavity
working in the TE102 mode. Variable-temperature measurements
were conducted with an Oxford continuous-flow helium cryostat
(temperature range 3.6-300 K). Accurate frequency values were
provided by a frequency counter built in the microwave bridge.
Solution spectra were acquired in toluene for all of the complexes.
Sample preparation was performed under a nitrogen atmosphere.
[Fe(BQA)2][BPh4] (2). HBQA and (0.82 g, 3.02 mmol) and
FeCl3 (anhydrous) (245 mg, 1.5 mmol) were added to a flask and
stirred in CH2Cl2 (25 mL). A solution of Na2CO3 (320 mg, 3.05
mmol) and NaBPh4 (517 mg, 1.5 mmol) in H2O (30 mL) was then
added to this slurry. The reaction mixture was stirred for 20 h at
room temperature. The product was extracted into CH2Cl2 and
washed with H2O (3 × 25 mL). The organic phase was evaporated
to dryness to yield a red powder (0.98 g, 71%). 1H NMR (DMSO-
d6, 300 MHz, 25 °C): δ 29.1, 19.8, 7.17, 6.91 (t, J ) 6.6 Hz), 6.77
(t, J ) 6.6 Hz), -8.3, -29.0, -61.7, -65.3. UV-vis [λmax/nm
(ε/M-1 cm-1)]: 1030 (11 000), 680 (2700), 514 (33 000), 418
(49 000), 306 (90 000). ES-MS (electrospray): positive mode
(25) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth. 1970,
12, 237.
(26) Bennett, M. A.; Smith, A. K. J. Chem. Soc., Dalton Trans. 1974, 233.
(27) Elliott, G. P.; McAuley, N. M.; Roper, W. R. Inorg. Synth. 1989, 26,
184.
(24) Stoicheff, B. P Can. J. Phys. 1954, 82, 630.
11578 Inorganic Chemistry, Vol. 47, No. 24, 2008

Group VIII Chemistry of a Bis(8-quinolinyl)amido Ligand
[(BQA)2Fe]+ m/z 596, found (M)+ m/z 596; [Ph4B]- m/z 319, found
(M)- m/z 319. Anal. calcd for C60H44BFeN6: C, 75.45; H, 4.58; N,
11.12. Found: C, 75.22; H, 4.68; N, 11.00.
diffusion of petroleum ether into benzene. 1H NMR (CD2Cl2, 300
MHz, 25 °C): δ 8.44 (dd, J ) 4.8 Hz, 1.5 Hz, 2H), 7.62 (m, 12H),
7.08 (d, J ) 7.8 Hz, 2H), 6.94 (t, J ) 8.2 Hz, 2H), 6.75-6.87 (m,
20 H), 6.48 (d, J ) 7.8 Hz, 4H), 6.38 (dd, J ) 4.8 Hz, 1.5 Hz,
4H). 31P {1H} NMR (C6D6, 121.4 MHz, 25 °C): δ -8. ES-MS
(electrospray): calcd for C54H42ClN3P2Os (M) m/z 1020, found (M
+ H) m/z 1021, 986 (M - Cl). Anal. calcd for C54H42ClN3P2Os:
C, 63.55; H, 4.15; Cl, 3.47; N, 4.12. Found: C, 63.46; H, 4.02; N,
4.10.
(BQA)RuCl(cod) (3). A suspension of Ru(cod)Cl2 (0.36 g, 1.3
mmol) in toluene (10 mL) was treated with a solution of [BQA][Li]
(0.35 g, 1.3 mmol) in toluene (10 mL) at room temperature. After
the mixture was stirred for 48 h, the solvent was removed in vacuo.
The residue was extracted with dichloromethane and filtered through
Celite on a sintered glass frit to yield a purple filtrate. Layering
the filtrate with petroleum ether precipitated a purple solid. The
product was collected via filtration, washed with copious amounts
cis-(BQA)OsCl(PPh3)2 (7). A solution of HBQA (500 mg, 1.84
mmol) and NEt3 (373 mg, 3.69 mmol) in CH2Cl2 (5 mL) was added
to a stirring solution of OsCl2(PPh3)3 (1.93 g, 1.84 mmol) in CH2Cl2
(8 mL). The reaction solution was heated to 65 °C for 5 h. The
reaction was then cooled to room temperature, and the volatiles
were removed in vacuo. The brown solid was washed with ethanol
(2 × 15 mL), Et2O (2 × 15 mL), and petroleum ether (2 × 15
mL). The remaining solid was dried in vacuo, yielding 1.26 g of 7
(67%). Vapor diffusion of petroleum ether into a solution of 7 in
1
of petroleum ether, and dried in vacuo (0.41 g, 62%). H NMR
(CDCl3, 300 MHz): δ 9.12-9.11 (m, 2H), 8.12-8.09 (m, 2H),
7.90-7.87 (m, 2H), 7.48-7.37 (m, 2H), 7.01-6.98 (m, 2H),
4.52-4.50 (m, 2H), 3.19-3.17 (m, 2H), 2.67-2.60 (m 2H),
2.29-2.20 (m, 2H), 1.96-1.92 (m, 2H), 1.80-1.74 (m, 2H). 13C
{1H} NMR (CDCl3, 75 MHz): δ 149.94, 137.14, 131.68, 128.83,
128.42, 122.60, 122.03, 113.52, 112.85, 94.75, 89.92, 30.39, 28.68.
UV-vis [λmax/nm (ε/M-1 cm-1)]: 324 (9900), 302 (7000), 590
(6200). Anal. calcd for C26H24ClN3Ru: C, 60.64; H, 4.70; N, 8.16.
Found: C, 60.73; H, 4.82; N, 7.89.
1
benzene yielded crystals of the trans product 6. H NMR (C6D6,
300 MHz, 25 °C): δ 8.8 (dd, J ) 4.8 Hz, 1.5 Hz, 2H), 7.6-6.5 (m,
36 H), 6.40 (dd, J ) 4.8 Hz, 1.5 Hz, 4H). 31P {1H} NMR (C6D6,
121.4 MHz, 25 °C): δ 2.2 (d, J ) 10.7 Hz), -0.92 (d, J ) 10.7
Hz). ES-MS (electrospray): calcd for C54H42ClN3P2Os (M)+ m/z
1020, found (M + H) m/z 1021, 986 (M - Cl).
Ru(BQA)2 (4). A suspension of Ru(cod)Cl2 (0.36 g, 1.3 mmol)
in toluene (10 mL) was added to a solution of [BQA][Li] (0.72 g,
2.6 mmol) in toluene (10 mL) in a bomb reactor with a Teflon
stopcock. The mixture was heated at reflux for 48 h. The volatiles
were removed in vacuo, and the residue was extracted with
dichloromethane and filtered through Celite on a sintered glass frit
to yield a red-purple filtrate. Layering the filtrate with petroleum
ether precipitated a burgundy solid. The product was collected via
filtration, washed with copious amounts of petroleum ether, and
[(terpy)Ru(BQA)][BPh4] (9). A solution of HBQA (32.6 mg,
0.12 mmol) and NEt3 (30 mg, 0.37 mmol) in CH2Cl2 (5 mL) was
added to a stirring solution of (tpy)RuCl2(PPh3) (50 mg, 0.075
mmol) and NaBPh4 (15 mg, 0.075 mmol) in ethanol (5 mL) at
room temperature. The reaction solution was then heated at 65 °C
for 15 h. The reaction mixture was then cooled to room temperature,
and the volatiles were removed in vacuo. The red solid was washed
with Et2O (2 × 15 mL) and petroleum ether (2 × 15 mL). The
remaining solid was dried in vacuo, yielding 59.6 mg of analytically
pure material (86%). ES-MS (electrospray): calcd for C33H23N6Ru
(M)+ m/z 605, found (M+) m/z 605. Anal. calcd for C57H43BN6Ru:
C, 74.10; H, 4.69; N, 9.10. Found: C, 74.35; H, 4.75; N, 9.06.
trans-(BQA)RuCl(PEt3)2 (10). A blue solution of 5 (0.15 g, 0.47
mmol) in toluene (10 mL) was treated with neat triethylphosphine
(0.20 mL, 2.0 mmol) at room temperature. The mixture was heated
to reflux for 18 h. The reaction mixture was cooled down, and all
volatile materials were removed in vacuo. The green solids were
washed with Et2O (3 × 15 mL) and petroleum ether (3 × 15 mL).
The remaining green solid was dried in vacuo to yield analytically
1
dried in vacuo (0.83 g, 89%). H NMR (CD2Cl2, 300 MHz, 25
°C): δ 9.10 (dd, J ) 4.8 Hz, 1.5 Hz, 4H), 7.16 (d, J ) 7.8 Hz,
4H), 7.05 (m, J ) 8.1 Hz, 4H), 6.65 (m, J ) 7.8 Hz, 8H), 6.35
(dd, J ) 4.8 Hz, 1.5 Hz, 4H). 13C {1H} NMR (CD2Cl2, 75 MHz):
δ 150, 138, 132, 129, 128.4, 122.8, 122. Anal. calcd for
C36H24N6Ru: C, 67.38; H, 3.77; N, 13.10. Found: C, 67.63; H, 3.66;
N, 13.12.
trans-(BQA)RuCl(PPh3)2 (5). A solution of HBQA (500 mg,
1.84 mmol) and NEt3 (373 mg, 3.69 mmol) in CH2Cl2 (5 mL) was
added to a stirring solution of RuCl2(PPh3)4 (2.25 g, 1.84 mmol)
in CH2Cl2 (8 mL). The reaction solution was heated to 65 °C for
5 h. The reaction was then cooled to room temperature and the
solvent removed in vacuo. The green solid was washed with ethanol
(2 × 15 mL), Et2O (2 × 15 mL), and petroleum ether (2 × 15
mL). The remaining solid was dried in vacuo, yielding 1.21 g of 5
(70.2%). Crystals of (BQA)RuCl(PPh3)2 were grown by vapor
1
pure material (0.073 g, 70%). H NMR (C6D6, 300 MHz): δ 9.06
(dd, J ) 4.8 Hz, 1.5 Hz, 4H), 7.18 (d, J ) 7.8 Hz, 4H), 7.04 (t, J
) 8.2 Hz, 4H), 6.72 (d, J ) 7.8 Hz, 8H), 6.40 (dd, J ) 4.8 Hz, 1.5
Hz, 4H), 1.82 (m, 12 H), 0.70 (d, 18H). 31P{1H} NMR (C6D6, 121
MHz) δ 11.8. Anal. calcd for C30H42ClN3P2Ru: C, 56.02; H, 6.58;
N, 6.53. Found: C, 55.88; H, 6.48; N, 6.51.
1
diffusion of petroleum ether into benzene. H NMR (C6D6, 300
MHz, 25 °C): δ 9.036 (dd, J ) 4.8 Hz, 1.5 Hz, 2H), 7.49 (m, 12H),
7.08 (d, J ) 7.8 Hz, 2H), 6.96 (t, J ) 8.1 Hz, 2H), 6.75-6.87 (m,
20 H), 6.53 (d, J ) 7.8 Hz, 4H), 6.40 (dd, J ) 4.8 Hz, 1.5 Hz,
4H). 31P {1H} NMR (C6D6, 121.4 MHz, 25 °C): δ 29.2. ES-MS
(electrospray): calcd for C54H42ClN3P2Ru (M)- m/z 931, found (M
+ H) m/z 931, 669 (M - PPh3). Anal. calcd for C54H42ClN3P2Ru:
C, 69.63; H, 4.55; N, 4.51. Found: C, 68.93; H, 4.69; N, 4.49.
trans-(BQA)OsCl(PPh3)2 (6). A solution of [BQA][Li] (300 mg,
1.11 mmol) in toluene (5 mL) was added to a stirring solution of
OsCl2(PPh3)4 (1.156 g, 1.11 mmol) in toluene (8 mL) at room
temperature. The reaction solution was heated to 65 °C for 5 h.
The reaction was then cooled to room temperature, and the volatiles
were removed in vacuo. The green solid was washed with ethanol
(2 × 15 mL), Et2O (2 × 15 mL), and petroleum ether (2 × 15
mL). The remaining solid was dried in vacuo, yielding 1.04 g of
analytically pure material (92%). Crystals of 6 were grown by vapor
trans-(BQA)RuCl(PMe3)2 (11). A blue solution of 5 (0.44 g,
0.47 mmol) in THF (10 mL) was treated with neat trimethylphos-
phine (0.19 mL, 1.9 mmol) at -30 °C. The mixture was allowed
to warm to room temperature, and during that time, the solution
turned green. After the mixture was stirred at room temperature
for 1 h, all volatile materials were removed in vacuo. Flash column
chromatography with 4:1 toluene/ethyl acetate yielded a black
purple analytically pure solid (0.18 g, 69%) (Rf ) 0.21). 1H NMR
(C6D6, 300 MHz): δ 9.06-9.03 (m, 2H), 7.70-7.67 (m, 2H),
7.34-7.22 (m, 4H), 6.74-6.72 (m, 2H), 6.58-6.53 (m, 2H), 0.68
(t, J ) 3.0 Hz, 18H). 13C{1H} NMR (C6D6, 75 MHz): δ 152.56,
151.74, 148.27 (t, J ) 2.4 Hz), 132.32 (t, J ) 1.7 Hz), 131.78,
128.14, 121.94, (t, J ) 1.6 Hz), 113.69, 113.36, 11.03 (t, J ) 11.3
Hz). 31P{1H} NMR (C6D6, 121 MHz): δ 0.47. ES-MS (electro-
Inorganic Chemistry, Vol. 47, No. 24, 2008 11579

Betley et al.
spray): calcd for C24H30ClN3P2Ru (M)+ m/z 559, found (M+) m/z
559. Anal. calcd for C24H30ClN3P2Ru: C, 51.57; H, 5.41; N, 7.52.
Found: C, 51.66; H, 5.35; N, 7.43.
azide (48 mg, 0.70 mmol). The mixture was stirred at 50 °C for
4 h. The volatiles were then removed in vacuo. The resulting residue
was extracted with benzene and filtered through a pad of Celite.
The filtrate was concentrated in vacuo, triturated with petroleum
trans-(BQA)RuBr(PMe3)2 (12). A green solution of 11 (0.13
g, 0.23 mmol) in 4 mL of THF/MeOH (1:1) was mixed with
potassium bromide (90 mg, 0.76 mmol) at room temperature. The
mixture was heated to 50 °C for 4 h, cooled, and filtered over a
pad of Celite. The filtrate was dried in vacuo, then redissolved in
toluene and flashed through silica gel. The volatiles were removed
in vacuo to yield a purple solid. The purple product was washed
with petroleum ether (2 × 15 mL) and dried in vacuo (0.11 g, 77%).
1H NMR (C6D6, 300 MHz): δ 9.19-9.17 (m, 2H), 7.70-7.67 (m,
2H), 7.30-7.22 (m, 4H), 6.73-6.70 (m, 2H), 6.53-6.48 (m, 2H),
0.72 (t, J ) 3.0 Hz, 18H). 13C{1H} NMR (C6D6, 75 MHz): δ
152.02, 151.52, 149.72 (t, J ) 2.3 Hz), 132.42, 131.68, 128.12,
122.02, 113.66, 113.41, 11.54 (t, J ) 11.5 Hz). 31P{1H } NMR
(C6D6, 121 MHz): δ -0.94. Anal. calcd for C24H30BrN3P2Ru: C,
47.77; H, 5.01; N, 6.96. Found: C, 50.72; H, 5.30; N, 6.50.
trans-(BQA)RuI(PMe3)2 (13). A green solution of 11 (89 mg,
0.16 mmol) in 4 mL of THF/MeOH (1:1) was mixed with potassium
iodide (90 mg. 0.54 mmol) at room temperature. The mixture was
heated at 50 °C for 4 h, filtered over a pad of Celite, and the volatiles
removed in vacuo to yield a purple solid. The filtrate was dried in
vacuo, then redissolved in toluene and flashed through silica gel.
Removal of the volatiles in vacuo afforded analytically pure material
(87 mg, 84%). 1H NMR (C6D6, 300 MHz): δ 9.38-9.35 (m, 2H),
7.71-7.68 (m, 2H), 7.28-7.22 (m, 4H), 6.70-6.68 (m, 2H),
6.46-6.41 (m, 2H), 0.79 (t, J ) 3.0 Hz, 18H). 13C{1H } NMR
(C6D6, 75 MHz): δ 152.59 (m), 151.50, 150.73, 132.75, 131.79,
128.30, 122.32, 113.82, 113.65, 12.83 (t, J ) 11.9 Hz). 31P{1H }
NMR (C6D6, 121 MHz): δ -2.96. Anal. calcd for C24H30IN3P2Ru:
C, 44.32; H, 4.65; N, 6.46. Found: C, 44.32; H, 4.70; N, 6.48.
trans-(BQA)RuH(PMe3)2 (14). To a green solution of 11 (37
mg, 0.066 mmol) in toluene (5 mL) was added 68 µL of a 0.25 M
solution of LiAlH4 in THF at room temperature. The mixture was
stirred at room temperature for 5 h, after which the volatiles were
removed in vacuo. The residue was extracted into toluene and
filtered through a Celite pad. The volatiles were removed in vacuo,
and the solid obtained was triturated with petroleum ether to give
an analytically pure, black-green solid (26 mg, 75%). Scaling this
reaction resulted in drastically diminished yields. 1H NMR (C6D6,
300 MHz): δ 8.44 (br, s, 2H), 7.87-7.84 (m, 2H), 7.39-7.28 (m,
4H), 6.75-6.72 (m, 2H), 6.37-6.33 (m, 2H), 0.80 (br, s, 18H),
1
ether, and dried in vacuo to yield a green solid (64 mg, 64%). H
NMR (C6D6, 300 MHz): δ 8.78-8.75 (m, 2H), 7.66-7.63 (m, 2H),
7.31-7.20 (m, 4H), 6.72-6.69 (m, 2H), 6.59-6.54 (m, 2H), 0.56
(t, J ) 3.0 Hz, 18H). 31P{1H} NMR (C6D6, 121 MHz): δ 1.66. IR
(Nujol/KBr): νN3 ) 2028.1 cm-1. Anal. calcd for C24H30N6P2Ru:
C, 50.97; H, 5.35; N, 14.86. Found: C, 51.14; H, 5.23; N, 14.40.
3,5-(CF3)2Ph-QAH (17). A 200 mL reaction vessel equipped
with a Teflon stopcock and stir bar was charged with Pd2(dba)3
(0.218 g, 0.238 mmol), 1,1′-bis(diphenylphosphino)ferrocene (DPPF)
(0.264 g, 0.476 mmol), and toluene (30 mL) under a dinitrogen
atmosphere. The resulting solution was allowed to stir for 5 min,
after which 3,5-bis(triflouromethyl)bromobenzene (3.49 g, 11.9
mmol), 8-aminoquinoline (2.48 g, 11.9 mmol), and additional
toluene (70 mL) were added. The subsequent addition of sodium
tert-butoxide (1.60 g, 16.66 mmol) resulted in a brown solution
that was stirred vigorously for three days at 110 °C under a vacuum.
The solution was then allowed to cool and filtered through a silica
plug that was then extracted with dichloromethane to ensure
complete removal of the desired product. Concentration of the
collected extracts and removal of the solvent yielded a crude red
solid (3.98 g, 94%). Purification by flash chromatography on silica
gel (4:1 toluene/ethyl acetate) yielded a burgundy red liquid as a
spectroscopically pure and synthetically useful compound (3.7 g,
87%). 1H NMR (C6D6, 300 MHz, 25 °C): δ 8.50 (dd, J ) 1.8, 4.2
Hz, 1H), 8.40 (s, 1H), 7.53 (dd, J ) 1.8, 8.4 Hz, 1H), 7.36 (m, J
) 0.9 Hz, 1H), 7.28 (s, 2H), 7.23 (dd, J ) 1.5, 7.2 Hz, 1H),
6.95-7.04 (m, 2H), 6.82 (dd, J ) 4.2, 4.2 Hz, 1H). 13C NMR (C6D6,
75.409 MHz, 25 °C): δ 148.1, 144.2, 139.6, 138.7, 136.5, 133.3,
132.9, 129.5, 127.6, 126.1, 122.4, 119.4, 118.2, 114.5 (m), 110.1.
19F NMR (C6D6, 282.127 MHz, 25 °C): δ -63.4. ES-MS (elec-
trospray): calcd for C17H10F6N2 (M)+ m/z 356, found (M + H)+
m/z 357.
[3,5-(CF3)2-(C6H3)QA][Na(Et2O)] (18). A suspension of NaH
(60% by weight; 57 mg, 1.4 mmol) in Et2O (2 mL) was added to
a solution of 3,5-(CF3)2Ph-QAH (500 mg, 1.4 mmol) in Et2O (4
mL). Upon heating to reflux, a red-orange salt precipitated. After
10 h of heating, the reaction was cooled to room temperature, and
the solvent decanted away. The salt was washed with petroleum
ether (4 × 5 mL) and dried in a vacuum to afford an orange powder
(544 mg, 86%). Hydrolysis of the salt with water cleanly affords
2
-11.75 (t, JP-H ) 27.4 Hz). 31P{1H} NMR (C6D6, 121 MHz): δ
1.47. IR (Nujol mull/KBr): νRu-H 1743.0 cm-1. Anal. calcd for
C24H31N3P2Ru: C, 54.95; H, 5.96; N, 8.01. Found: C, 54.99; H,
5.88; N, 7.96.
the parent amine. H NMR (C6D6, 300 MHz, 25 °C): δ 7.58 (dd,
1
J ) 1.8, 4.2 Hz, 1H), 7.49 (dd, J ) 1.8, 8.4 Hz, 1H), 7.38 (dd, J
) 1.2, 7.8 Hz, 1H), 7.18 (t, J ) 7.8 Hz, 1H), 7.12 (s, 1H), 7.08 (s,
2H), 6.84 (dd, J ) 1.2, 7.8 Hz, 1H), 6.65 (dd, J ) 4.2, 8.4 Hz,
1H), 3.01 (q, (CH3CH2)2O J ) 7.2 Hz, 4H), 0.86 (t, (CH3CH2)2O
J ) 7.2 Hz, 6H). 19F NMR (C6D6, 282.127 MHz, 25 °C): δ -65.
(BQA)Ru(3,5-(CF3)2-(C6H3)QA)(PPh3) (19). A solution of 18
(245.1 mg, 0.54 mmol) in THF (2 mL) was added dropwise to a
stirring solution of 5 (500 mg, 0.54 mmol) in THF (4 mL). The
reaction solution was heated to 80 °C for 3 h. The reaction was
then cooled to room temperature and the volatiles removed in vacuo.
The purple solid was washed with a 3:1 petroleum ether and ethanol
mix (3 × 5 mL). The remaining solid was dried in vacuo, yielding
476 mg of analytically pure material (90%). Crystals were grown
by cooling a solution of 19 in benzene layered with petroleum ether.
1H NMR (C6D6, 300 MHz, 25 °C): δ 8.99 (dd, J ) 1.2, 4.8 Hz,
1H), 7.57 (dd, J ) 1.2, 4.8 Hz, 2H), 7.49 (dd, J ) 1.2, 8.2 Hz,
1H), 7.19 (d, J ) 1.2 Hz, 1H), 6.77-7.08 (m, 14H), 6.75 (m, 6H),
6.58-6.64 (m, 5H), 6.53 (dd, J ) 5.4, 7.2 Hz, 1H), 6.44 (s, 2H),
trans-(BQA)RuMe(PMe3)2 (15). A green solution of 11 (0.10
g, 0.19 mmol) in toluene (5 mL) was treated with 3.5 equiv of
MeLi (1.0 M) in diethyl ether at -30 °C. The mixture was then
heated at 60 °C for 12 h. The reaction mixture was cooled to room
temperature, and the excess MeLi was quenched with ethanol. The
volatiles were then removed in vacuo. The resulting residue was
extracted with benzene and filtered through a pad of Celite. The
filtrate was concentrated in vacuo, triturated with petroleum ether,
1
and dried in vacuo to yield a green solid (51 mg, 50%). H NMR
(C6D6, 300 MHz): δ 8.28-8.26 (m, 2H), 7.84-7.81 (m, 2H),
7.37-7.30 (m, 4H), 6.75-6.72 (m, 2H), 6.47-6.42 (m, 2H), 0.57
(t, J ) 2.7 Hz, 18H, P(CH3)3), 0.01 (t, J ) 9.8 Hz, 3H, RuCH3).
31P{1H} NMR (C6D6, 121 MHz): δ 3.18. Anal. calcd C25H33N3P2Ru:
C, 55.75; H, 6.18; N, 7.80. Found: C, 55.36; H, 6.00; N, 7.78.
trans-(BQA)RuN3(PMe3)2 (16). A green solution of 11 (0.10
g, 0.19 mmol) in 10 mL of CH2Cl2 was treated with solid sodium
11580 Inorganic Chemistry, Vol. 47, No. 24, 2008

Group VIII Chemistry of a Bis(8-quinolinyl)amido Ligand
6.08 (dd, J ) 4.8, 8.2 Hz, 2H). 31P {1H} NMR (C6D6, 121.4 MHz,
25 °C): δ 50.5. 19F NMR (C6D6, 282.127 MHz, 25 °C): δ -64.
ES-MS (electrospray): calcd for C53H36F6N5PRu (M)+ m/z 988,
found (M + H)+ m/z 989. Anal. calcd for C53H36F6N5PRu: C, 64.37;
H, 3.67; N, 7.08. Found: C, 64.38; H, 3.64; N, 7.08.
) 7.5 Hz, 2 H), 6.27-6.44 (m, 10 H), 2.78 (d, J ) 12 Hz, 2 H),
2.02 (d, J ) 13.8 Hz, 2 H). 13C NMR (C6D6, 75.409 MHz, 25 °C):
δ 155, 151, 149, 137, 135, 133.2, 133.1, 132.6, 132.5, 131, 129,
128.5, 128.4, 128, 127, 126.8, 126.7, 123, 120, 114. 31P {1H} NMR
(C6D6, 121.4 MHz, 25 °C): δ 35.17 (d, J ) 35 Hz), 18.81 (d, J )
35 Hz). 11B {1H} NMR (C6D6, 128.3 MHz, 25 °C): δ -11.9. IR:
(CH2Cl2)νCO ) 1970 cm-1. Anal. calcd for C57H46BN3OP2Ru: C,
71.10; H, 4.82; N, 4.36. Found: C, 71.06; H, 4.70; N, 4.28.
[trans-(BQA)Ru(CO)(PPh3)2][BPh4] (25). NaBPh4 (18.2 mg,
0.05 mmol) in ethanol (1 mL) was added to a solution of 5 (45
mg, 0.05 mmol) in THF (2 mL) in a 10 mL Schlenk flask equipped
with a stir bar and septum. The flask was evacuated, then exposed
to 1 atm of CO gas. The green solution reddens instantly upon
exposure to CO. The reaction was allowed to stir for 30 min before
the volatiles were removed in vacuo. The red solid was washed
with ethanol (2 × 3 mL) and Et2O (2 × 3 mL). The remaining
solid was dried in vacuo, yielding 49 mg of analytically pure
material (82%). 1H NMR (C6D6, 300 MHz, 25 °C): complex pattern
of resonances between 8.55 and 6.98 ppm (62H). 31P {1H} NMR
(C6D6, 121.4 MHz, 25 °C): δ 30.1. IR: (CH2Cl2/KBr): νCO 1970
cm-1. ES-MS (electrospray): calcd for C55H42N3OP2Ru (M)+ m/z
924, found (M)+ m/z 924, 662 (M - PPh3). Anal. calcd for
C79H62BN3OP2Ru: C, 76.32; H, 5.03; N, 3.38. Found: C, 76.15; H,
4.87; N, 3.36.
(BQA)Ru(3,5-(CF3)2-(C6H3)QA)(CO) (20). A 100 mL reaction
vessel equipped with a Teflon stopcock and stir bar was charged
with a solution of 19 (50 mg, 0.05 mmol) in toluene (15 mL). The
reaction vessel was evacuated and then exposed to 1 atm of CO
gas. The reaction mixture was heated at reflux with vigorous stirring
for 8 h. The reaction was then cooled to room temperature and the
volatiles removed in vacuo. The red solid was washed with a 3:1
petroleum ether and ethanol mix (3 × 5 mL). The remaining solid
was dried in vacuo, yielding 36 mg of analytically pure material
(95%). 1H NMR (C6D6, 300 MHz, 25 °C): δ 9.01 (dd, J ) 1.2, 4.8
Hz, 1H), 7.50 (dd, J ) 1.2, 4.8 Hz, 2H), 7.48 (dd, J ) 1.2, 8.2 Hz,
1H), 7.20 (d, J ) 1.2 Hz, 1H), 6.58-7.08 (m, 11H), 6.52 (dd, J )
5.4, 7.2 Hz, 1H), 6.44 (s, 2H), 6.08 (dd, J ) 4.8, 8.2 Hz, 2H). 19
F
NMR (C6D6, 282.127 MHz, 25 °C): δ -64. Anal. calcd for
C36H21F6N5ORu: C, 57.30; H, 2.80; N, 9.28. Found: C, 57.02; H,
2.78; N, 9.18.
[(BQA)RuCl(PhBP2)][NEt4]
(21).
A
solution
of
[Ph2B(CH2PPh2)2][NEt4] (354 mg, 0.51 mmol) in THF (2 mL) was
added dropwise to a stirring solution of 5 (471 mg, 0.51 mmol) in
THF (4 mL). The reaction solution was heated to 80 °C for 3 h.
The reaction was then cooled to room temperature and the solvent
removed in vacuo. The dark purple solid was washed with Et2O (2
× 15 mL) and petroleum ether (2 × 15 mL). The remaining solid
was dried in vacuo, yielding 497 mg of analytically pure material
(89%). Crystals of 21 were grown by vapor diffusion of petroleum
[trans-(BQA)Ru(CH3CN)(PPh3)2][BPh4] (24). A solution of 5
(88 mg, 0.094 mmol) in a mixture of acetonitrile and methanol (2
mL/4 mL) was added to a solution of NaBPh4 (51 mg, 0.15 mmol)
in methanol (2 mL) at room temperature. The resulting mixture
was stirred at room temperature for 4 h; then, the volatiles were
removed in vacuo. The solid residue was extracted with dichlo-
romethane (5 mL) and filtered through a Celite pad. The volatiles
were removed in vacuo, and the purple solid was triturated with
petroleum ether. The solids were dried in vacuo to afford 78 mg
1
ether into THF. H NMR (C6D6, 300 MHz, 25 °C): δ 8.46 (bs,
4H), 7.93 (bs, 2H), 7.75 (bs, 2H), 7.49 (d, J ) 6.3 Hz, 2H),
6.95-7.39 (m, 18H), 6.79 (t, J ) 7.2 Hz, 5H), 6.67 (t, J ) 7.2 Hz,
4H), 6.36-6.47 (m, 9H), 3.29 (q, J ) 7.5 Hz, 8H), 2.35 (bs, 2H),
1.81 (bs, 2H), 1.23 (tt, J ) 1.5, 7.2 Hz, 12 H). 31P {1H} NMR
(C6D6, 121.4 MHz, 25 °C): δ 54 (d, J ) 36 Hz), 28.3 (d, J ) 36
Hz). 11B {1H} NMR (C6D6, 128.3 MHz, 25 °C): δ -11.8. Anal.
calcd for C64H66BClN4P2Ru: C, 69.85; H, 6.04; N, 5.09. Found: C,
69.78; H, 6.05; N, 5.08.
1
of analytically pure material (67%). H NMR (CDCl3, 300 MHz,
25 °C): complex pattern of resonances between 8.48 and 7.00 ppm
(62H). 31P{1H} NMR (CDCl3, 121 MHz) δ 28.7 (bs). Anal. calcd
for C78H62BN3P2Ru: C, 77.09; H, 5.14; N, 3.46. Found: C, 77.48;
H, 5.69; N, 3.69.
[trans-(BQA)Os(CO)(PPh3)2][PF6] (26). A solution of TlPF6
(13.6 mg, 0.02 mmol) in THF (1 mL) was added to a solution of
6 (40 mg, 0.02 mmol) in THF (2 mL) in a 10 mL Schlenk flask
equipped with a stir bar and septum. The flask was evacuated, then
exposed to 1 atm of CO gas. The green solution reddens after
stirring vigorously over the period of 1 h. The reaction was allowed
to stir for 5 h, and then the volatiles were removed in vacuo. The
red solid was washed with ethanol (2 × 3 mL) and Et2O (2 × 3
mL). The remaining solid was dried in vacuo, yielding 48 mg of
(BQA)Ru[Ph2BP2] (22). Solid 21 (100.6 mg, 0.09 mmol) was
stirred vigorously in ethanol (6 mL) for 30 min. A red solid
precipitated from solution and was isolated by decanting the liquor
away. The solids were dissolved in CH2Cl2 and filtered through a
pad of Celite. The solvent was removed in vacuo, and the remaining
wine red solid was washed with petroleum ether (2 × 3 mL) and
dried in vacuo, yielding 72 mg of analytically pure material (84%).
1H NMR (C6D6, 300 MHz, 25 °C): δ 8.17 (s, 5 H), 7.72 (d, J )
4.8 Hz, 2H), 7.54 (m, 10 H), 7.30 (d, J ) 6 Hz, 4H), 7.04 (d, J )
8.7 Hz, 2H), 6.851 (d, J ) 7.8 Hz, 2H), 6.50 (m, 10 H), 6.2 (m, 2
H), 5.81 (m, 2 H), 2.69 (s, 4 H). 31P {1H} NMR (C6D6, 121.4 MHz,
25 °C): δ 69.45. 11B {1H} NMR (C6D6, 128.3 MHz, 25 °C): δ
-12.1. Anal. calcd for C56H46BN3P2Ru: C, 71.95; H, 4.96; N, 4.50.
Found: C, 71.78; H, 5.05; N, 4.44.
(BQA)Ru(CO)(PhBP2) (23). A 20 mL vial containing 21 (60
mg, 0.054 mmol) in CH2Cl2 (2 mL) was sparged with CO gas.
The solution instantly reddened upon contact with the gas. The
solvent was removed in vacuo, and the remaining red solid was
washed with ethanol (2 × 2 mL). The resulting powder was washed
with petroleum ether (2 × 3 mL) and dried in vacuo, yielding 45
mg of analytically pure material (86%). 1H NMR (C6D6, 300 MHz,
25 °C): δ 7.90 (m, 4 H), 7.75 (d, J ) 4.5 Hz, 2H), 7.53 (d, J ) 7.2
Hz, 2 H), 7.32 (d, J ) 8.1 Hz, 2H), 7.11-7.22 (m, 8H), 7.04 (t, J
) 7.5 Hz, 4H), 6.92 (s, 6 H), 6.67 (t, J ) 6.6 Hz, 2 H), 6.53 (d, J
1
analytically pure material (90%). H NMR (C6D6, 300 MHz, 25
°C): complex pattern of resonances between 8.58 and 6.56 ppm
(42H). 31P {1H} NMR (C6D6, 121.4 MHz, 25 °C): δ 0.31. IR:
(CH2Cl2/KBr)νCO ) 1921 cm-1. ES-MS (Electrospray): calcd for
C55H42N3OOsP2 (M)+ m/z 1013, found (M)+ m/z 1014. Anal. calcd
for C55H42F6N3OOsP3: C, 57.04; H, 3.66; N, 3.63. Found: C, 56.64;
H, 3.51; N, 3.60.
[trans-(BQA)RuCl(PPh3)2][OTf] (27). To a vigorously stirring
solution of 5 (0.11 g, 0.12 mmol) in toluene (5 mL) was added
solid AgOTf (30 mg, 0.12 mmol) at room temperature. The reaction
mixture turned brown instantly, while a black precipitate formed.
After the mixture was stirred for 1 h, the solution was filtered
through a Celite pad to remove the precipitate. The volatiles were
removed in vacuo. The solids were then extracted into CH2Cl2 (5
mL) and filtered again through a Celite pad. The volume of the
filtrate was reduced to 1 mL, layered with diethyl ether, and allowed
Inorganic Chemistry, Vol. 47, No. 24, 2008 11581

Betley et al.
to stand. A yellow precipitate formed and was isolated by decanting
the liquor. The solids were dried in vacuo to afford analytically
pure material (0.12 g, 93%). ES-MS (electrospray): calcd for
C54H42ClN3P2Ru (M)+ m/z 931, found (M + H)+ m/z 931. Anal.
calcd for C55H42ClF3N3O3P2RuS: C, 61.14; H, 3.92; N, 3.89. Found:
C, 60.81; H, 3.70; N, 3.76.
2H), 7.54 (t, J ) 7.8 Hz, 2H), 7.25 (dd, J ) 7.8, 7.8 Hz, 2H), 7.04
(d, J ) 7.8 Hz, 2H), 0.72 (t, J ) 2.7 Hz, 18H).
31P {1H} NMR
(CD2Cl2, 121.4 MHz, 25 °C): δ 0.42, -143 (sept, J ) 711 Hz).
ES-MS (electrospray): calcd for C24H30N5P2Ru (M)+ m/z 552, found
(M + H)+ m/z 524 (M - N2)+. IR (CH2Cl2/KBr): νNN 2129 cm-1
.
Anal. calcd for C24H30F6N5P3Ru: C, 41.39; H, 4.34; N, 10.05.
[trans-(BQA)Ru(N2)(PPh3)2][PF6] (30). TlPF6 (18.8 mg, 0.054
mmol) in THF (1 mL) was added to a solution of 5 (50 mg, 0.054
mmol) in THF (2 mL) at room temperature. The green solution
darkens to a midnight blue after stirring for several hours, and the
evolution of a white precipitate is noticeable. The reaction mixture
was allowed to stir for 24 h and was filtered through a Celite pad,
and then the volatiles were removed in vacuo. Dissolution of the
blue solids in CH2Cl2 caused a color change to an intense red. The
solution was filtered through a Celite pad, and the volatiles were
removed in vacuo. The red solid was washed with Et2O (2 × 3
mL). The remaining solid was dried in vacuo, yielding 56 mg of
analytically pure material (83%). 1H NMR (CD2Cl2, 300 MHz, 25
°C): complex pattern of resonances between δ 8.64 and 7.04 (42H).
31P {1H} NMR (CD2Cl2, 121.4 MHz, 25 °C): δ 25, -143 (sept, J
) 711 Hz). ES-MS (electrospray): calcd for C54H42ClN5P2Ru (M)+
m/z 924, found (M + H)+ m/z 896 (M - N2)+. IR: (CH2Cl2/KBr):
Found: C, 41.29; H, 4.15; N, 9.89.
[trans-(BQA)Os(N2)(PPh3)2][PF6] (32). A solution of TlPF6
(13.6 mg, 0.02 mmol) in THF (1 mL) was added to a solution of
6 (40 mg, 0.02 mmol) in THF (2 mL) at room temperature. The
green solution reddens after stirring vigorously over a period of
several hours. The reaction was allowed to stir for 24 h and was
filtered through a Celite pad, and then the volatiles were removed
in vacuo. The red solid was extracted into CH2Cl2 and filtered
through a Celite pad. The volatiles were removed in vacuo, and
the resultant solids were washed with Et2O (2 × 3 mL). The
remaining solid was dried in vacuo, yielding 48 mg of analytically
pure material (89%). 1H NMR (C6D6, 300 MHz, 25 °C): complex
pattern of resonances between 8.47 and 6.44 ppm (42H). 31P {1H}
NMR (C6D6, 121.4 MHz, 25 °C): δ -3.7. IR (CH2Cl2/KBr): νNN
2073 cm-1. ES-MS (electrospray): calcd for C54H42N5OsP2 (M)+
m/z 1013, found (M)+ m/z 1014, 986 (M - N2)+. Anal. calcd for
C54H42F6N5OsP3: C, 56.00; H, 3.66; N, 6.05. Found: C, 55.92; H,
3.61; N, 5.99.
ν
NN 2130 cm-1. Anal. calcd for C54H42F6N5P3Ru: C, 60.68; H, 3.96;
N, 6.55. Found: C, 60.55; H, 3.90; N, 6.48.
[trans-(BQA)Ru(N2)(PMe3)2][PF6] (31). TlPF6 (18.8 mg, 0.054
mmol) in THF (1 mL) was added to a solution of 5 (30 mg, 0.054
mmol) in THF (2 mL) at room temperature. The green solution
reddens after stirring for several hours, and the evolution of a white
precipitate is noticeable. The reaction mixture was allowed to stir
for 36 h and was filtered through a Celite pad, and then the volatiles
were removed in vacuo. The solids were dissolved in CH2Cl2 and
filtered through a Celite pad, and the volatiles were removed in
vacuo. The red solid was washed with Et2O (2 × 3 mL). The
remaining solid was dried in vacuo, yielding 36 mg of analytically
pure material (78%). 1H NMR (CD2Cl2, 300 MHz, 25 °C): δ 8.35
(d, J ) 5.1 Hz, 2H), 8.04 (d, J ) 7.8 Hz, 2H), 7.91 (d, J ) 7.8 Hz,
Acknowledgment. J.C.P. is grateful to the NSF for
financial support of this work (CHE-0750234 and CHE-
0132216). T.A.B. is grateful to the Department of Defense
for a graduate research fellowship.
Supporting Information Available: Crystallographic data (PDF
and CIF). This material is available free of charge via the Internet
at http://pubs.acs.org.
IC801047S
11582 Inorganic Chemistry, Vol. 47, No. 24, 2008