Syntheses, structures and redox properties of tris(pyrazolyl)borate-capped ruthenium vinyl complexes

Article abstract of DOI:10.1016/j.jorganchem.2012.09.001

Reaction of RuHCl(CO)(PPh₃)₃ with aryl alkynes HCCC₆H₄R-4 [1: R = N(C₆H₄Me-4) ₂ (a), OMe (b), Me (c), CO₂Me (d), NO₂ (e)] gives the five-coordinate vinyl complexes Ru(CHCHC₆H ₄R-4)Cl(CO)(PPh₃)₂ (2a-e). Reaction of 2a with excess PMe₃ gives crystallographically characterised Ru{CHCHC ₆H₄N(C₆H₄Me-4)₂-4}Cl(CO) (PMe₃)₃ (3a), whilst reaction of 2a-e with KTp affords Ru(CHCHC₆H₄R-4)(CO)(PPh₃)Tp (4a-e) bearing the facially capping Tp^- ligand. Electrochemical and spectroelectochemical properties of 4a-e are consistent with substantial redox activity associated with the vinyl ligand, and these properties have been satisfactorily modelled by DFT based calculations of electronic structure.

Full text of DOI:10.1016/j.jorganchem.2012.09.001

Journal of Organometallic Chemistry 721-722 (2012) 173e185
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Syntheses, structures and redox properties of tris(pyrazolyl)borate-capped
ruthenium vinyl complexesq
Julian D. Farmer a, Wing Y. Man a, Mark A. Fox a, Dmitry S. Yufit a, Judith A.K. Howard a, Anthony F. Hill b,
,
Paul J. Lowa
*
a Department of Chemistry, Durham University, South Rd, Durham DH1 3LE, UK
b Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
a r t i c l e i n f o
a b s t r a c t
Article history:
Reaction of RuHCl(CO)(PPh3)3 with aryl alkynes HC^CC6H4R-4 [1: R ¼ N(C6H4Me-4)2 (a), OMe (b), Me (c),
CO2Me (d), NO2 (e)] gives the five-coordinate vinyl complexes Ru(CH]CHC6H4R-4)Cl(CO)(PPh3)2 (2aee).
Reaction of 2a with excess PMe3 gives crystallographically characterised Ru{CH]CHC6H4N(C6H4Me-4)2-4}
Cl(CO)(PMe3)3 (3a), whilst reaction of 2aee with KTp affords Ru(CH]CHC6H4R-4)(CO)(PPh3)Tp (4aee)
bearing the facially capping Tpꢀ ligand. Electrochemical and spectroelectochemical properties of 4aee
are consistent with substantial redox activity associated with the vinyl ligand, and these properties have
been satisfactorily modelled by DFT based calculations of electronic structure.
Received 25 July 2012
Received in revised form
6 September 2012
Accepted 8 September 2012
Keywords:
Ruthenium
Vinyl
Ó 2012 Elsevier B.V. All rights reserved.
Redox non-innocence
Spectroelectrochemistry
1. Introduction
character noted in Jorgensen’s review. It is also implicit in these
descriptionsthatthebehaviouroftheligandisstronglyinfluencedby
The redox chemistry of Werner-style transition metal coordina-
tion complexes, [MLn], is usually governed by changes in the formal
metal oxidation state and occupation of frontier orbitals with
considerable metal d-orbital character. However, systems in which
redox character is more closely associated with changes in pop-
ulation of ligand-based orbitals have long been recognised, and
the nature of the metal fragment (metal and supporting ligands) to
which it is coordinated, and the same ligand may display redox
innocentornon-innocent behaviourdependingon therelative redox
potentials of the ligand and the supporting metal fragment, other
potentially redox active ligands and the synergistic s- and p-forward
and back-bonding interactions [3e5]. Keeping the judicial parlance,
spectroscopic evidence is required to establish the redox guilt or
innocence of a ligand, often supported by quantum mechanical
calculations [6]. Nevertheless, the capacity for both ligand and metal
to adjust their redox state has considerable implications for the
design of catalytic systems, with ligands used as electron reservoirs
or sinks to help shuttle electrons to a substrate [7e9].
activity in the area has expanded from simple O2/O2 ꢀ/O22ꢀ and NOþ/
ꢁ
NOꢁ/NOꢀ series through redox related families based on dithiolenes,
diimines, ortho-quinones to an expansive range of largerheterocyclic
and macrocyclic ligands. The combination of redox active metals
with redox active ligands leads to considerable scope for ambiguity
in oxidation state assignments [1], giving rise to descriptions of
‘innocent’ (those that allow unambiguous assignment of metal
oxidation state) and ‘suspect’ ligands coined by Jorgensen [2]. In
more recent times, the description of ligands as ‘suspect’, has often
given way to descriptions in terms of ‘non-innocent’ behaviour,
although this term should be reserved for systems in which the
ligand has established redox activity, rather than the suspect
Within the span of complexes in which redox activity can be well
described in terms of changes in metal (e.g. [Co(NH3)6]2þ/3þ) [10] or
ligand (e.g. [Cr(tBu2-bpy)3]3þ/2þ/1þ/0
) [11] oxidation state lie
complexes of intermediatecharacter inwhich theredoxactive orbitals
have extensively mixed metal and ligand character. For this latter
group there exists considerable ambiguity in terms of the precise
oxidation states of either component [4]. However, the extensive
mixing of metaleligand character which complicates the assignment
of accurate integer oxidation states to a particular atomic centre in
a strongly delocalised molecular framework underpins many of the
fascinating optoelectronic properties of this class of metal complex
[12]. It has now been firmly established that ruthenium alkynyl
q
Dedicated to Professor Thomas P. Fehlner, in recognition of his outstanding
contributions to organometallic chemistry.
* Corresponding author.
E-mail address: p.j.low@durham.ac.uk (P.J. Low).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.09.001

174
J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
complexes Ru(ChCR)(PP)Cp0 (P ¼ phosphine, PP ¼ bis(phosphine);
Cp0 ¼ Cp, Cp*) [13e15] and Ru(X)(ChCR)(PP)2 (X ¼ Cl, ChCR) [16]
2. Results and discussion
feature such extensive mixing of the metal d and alkynyl ligand
p-
2.1. Syntheses
orbitals. Vinyl complexes Ru(CH]CHR)Cl(CO)(PR03)2L (R ¼ Me, iPr, Ph;
L ¼ vacant coordination site, PR03, pyridine donor ligand, CO, NCR, etc)
[17] also fall in this latter ‘delocalised’ category for R ¼ H, But, Ph, and
exhibit increasing degrees of ligand redox character as the alkynyl or
vinyl ligand substituent R is made progressively lower and lower in
energy (e.g.1-naphthyl, 9-anthryl, ethynylphenyl) [18e20], and when
incorporated into bridging ligands spanning two strongly electron-
donating ruthenium fragments [21e28].
The reaction of terminal aryl alkynes, HC^CC6H4R-4 [1:
R ¼ N(C6H4Me-4)2 (a), OMe (b), Me (c), CO2Me (d), NO2 (e)], with
RuHCl(CO)(PPh3)3 in CH2Cl2 proceeded smoothly to give the five-
coordinate complexes Ru(CH]CHC6H4R-4)Cl(CO)(PPh3)2 (2aee),
evidenced by the developing red colouration of the reaction
mixture (Scheme 2). Complex 2a was isolated as a red solid,
following a series of precipitations, and characterised by way of
example. The IR spectrum of 2a in CH2Cl2 solution features
The complexes Ru(CH]CHR)Cl(CO)(PR03)2L, which are readily
prepared by insertion of an alkyne into the RueH bond in
RuHCl(CO)(PR03)n (n ¼ 2, 3) [29] offeran entry point to awide range of
vinyl complexes through facile substitution reactions of the sup-
porting phosphineandchlorideligandsbyawiderangeofneutraland
anionic mono and bidentate ligands (Scheme 1) [30,31]. The binding
of the ligand trans to the vinyl ligand is weakened by the strong trans
influence of the vinyl ligand, and inthecaseof bulkyphosphines, PR03,
the complexes are often isolated as the five-coordinate species
(L ¼ vacant site) [32e35], or exist as a mixture of the five- and six-
coordinate complexes (Scheme 1) [36]. The five-coordinate species
are convenient precursors to a range of derivatives through ligand
substitution reactions [37e44], giving considerable scope to tune the
metaleligand coordination sphere.
a strong
five-coordinate species Ru(CH]CHPh)Cl(CO)(PR03)2 (R0
1927 cmꢀ1; iPr,1911 cmꢀ1) and reflects the relative sensitivity of the
(CO) frequency to the electron-donating character of the PiPr3 and
n
(CO) band at 1932 cmꢀ1, which compares with other
Ph,
¼
n
PPh3 ligands, and relative insensitivity to the nature of the vinyl
ligand substituent [18]. In addition, the vinyl protons were identi-
fied from coupled resonances at 5.54 (d, JHH ¼ 13 Hz, RueCH]CH)
and 8.22 (dt, JHH ¼ 13 Hz, JHP ¼ 2 Hz, RueCH]CH), the latter being
additionally coupled to the two 31P nuclei of the phosphine ligands.
The trans-disposition of the phosphine ligands was evidenced
by the observation of a singlet in the 31P{1H} NMR spectrum at
d
29.5 ppm.
Reaction of red 2a with excess PMe3 gave the white complex Ru
This considerable flexibility in the coordination sphere presents
a wide range of interesting possibilities for fine-tuning the degree of
metal vs vinyl ligand redox character [5]; however, to date the vast
majority of investigations of the redox chemistry of ruthenium vinyl
complexes have been restricted to five-coordinate Ru(CH]CHR)
Cl(CO)(PiPr3)2 systems [17,18,21e23,45] or six-coordinate complexes
Ru(CH]CHR)Cl(CO)(PPh3)2L (L ¼ 4-ethyl-isonicotinate) [18], Ru(CH]
CHR)(CO)(O2CR)(PiPr3)2 [18] and Ru(CH]CHR)Cl(CO)(PMe3)3
[28,46].
In this report, we describe efforts to further tune the electronic
character of the RueCH]CHR fragment through the preparation and
study of the tris(pyrazolyl)borate (Tpꢀ) derivatives Ru(CH]CHC6H4R-
4)(CO)(PPh3)Tp. The tridentate tris(pyrazolyl)borate ligand occupies
a facially capping position on the octahedral (six-coordinate) metal
centre [43], whilstthe retention of the CO ligand provides a convenient
{CH]CHC6H4N(C6H4Me-4)2-4}Cl(CO)(PMe3)3 (3a) (Scheme 2),
which is a further example of the mer-Ru(CH]CHR)Cl(CO)(PMe3)3
system [28,46e48]. The vinyl proton resonances at 6.53 and
7.90 ppm displayed additional couplings to the three phosphine
ligands, giving rise to a ddt pattern in each case, whilst in turn the
31P{1H} NMR spectrum was characterised by a AM2 pattern. The
observation of the n
(CO) band at 1919 cmꢀ1 is consistent with the
electronic trends of the supporting ligands. Further reaction of 2ae
e with the potassium salt of tris(pyrazolyl)borate (KTp) gave
complexes Ru(CH]CHC6H4R-4)(CO)(PPh3)Tp (4aee) bearing the
facially capping Tpꢀ ligand [43,49] (Scheme 2). With the exception
of the orange-coloured NO2 substituted derivative 4e, these Tp
complexes were isolated as pale yellow or green coloured solids.
The choice of the Tpꢀ ligand was inspired by the analogy with the
anionic cyclopentadienyl ligand that has been used to support
many half-sandwich ruthenium complexes [50]. The Cpꢀ and Tpꢀ
ligands are isoelectronic, six-electron donors, which usually coor-
dinate in a tridentate manner, and lead to similar chemistry [51e
54]. As KTp is a commercially available, air-stable solid, [Ru(CR]
CHR)(CO)(PPh3)Tp] complexes are somewhat more readily avail-
able than the isoelectronic Cp analogues [43], and were chosen for
studies of the electrochemical properties and electronic structure
of ruthenium vinyl complexes.
n(CO) spectroscopic probe through which to assess the electron
densityatthe metalcentre [17]. The details of the syntheses, structures
and electrochemical properties of the complexes Ru(CH]CHC6H4R-
4)(CO)(PPh3)Tp (R ¼ N(C6H4Me-4)2, OMe, Me, CO2Me, NO2) are re-
ported together with UVeviseNIR and IR spectroelectrochemical
studies of [Ru(CH]CHC6H4R-4)(CO)(PPh3)Tp]nþ (n ¼ 0, 1). The
resulting descriptions of the redox character of the vinyl ligand are
supported by DFT calculations.
Scheme 1. A representative array of ligand substitution reactions associated with five-coordinate vinyl complexes Ru(CH]CHR)Cl(CO)(PR03)2.

J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
175
Scheme 2. The preparation of 2aee, 3a and 4aee.
The presence of the Tpꢀ ligand in the metal coordination
sphere was readily apparent from the usual series of multiplets
between 5.8 and 7.5 ppm arising from the pyrazoyl protons and
Reaction of RuHCl(CO)(PPh3)3 with HC^CC6H4CN-4 (1f) typi-
cally proceeds to give a yellow solution, likely containing a poly-
meric species {Ru(CH]CHC6H4CN)(CO)(PPh3)2}n. Whilst we were
unable to conclusively characterise this species, on one occasion
addition of KTp gave small quantities of Ru(CH]CHC6H4CN-
4)(CO)(PPh3)Tp (4f), which was identified crystallographically and
found to be isostructural with 4c and 4e. In the absence of full
spectroscopic characterisation, and the capricious nature of the
synthesis, the results of the structure determination have been
included in the Supporting information but no further study of this
compound has been undertaken.
the BeH resonance in the 1H{11B} spectrum at 4.64 ppm. In the 13
C
NMR spectrum, the carbonyl carbon was observed as a doublet
(JCP ¼ 15e17 Hz) near 207 ppm. The vinyl Ca carbon also gave rise
to a characteristic doublet (JCP w 14 Hz), the chemical shift of
which was rather more sensitive to the nature of the vinyl
substituent, and falling near
d 160 ppm for 4a, 4b and 4c bearing
the more electron-donating groups, and at 171.3 (4d) and 179.2
(4e) for those with strongly electron-withdrawing substituents,
clearly demonstrating the effectiveness of conjugation through the
vinyl ligand. The IR spectra of 4aee were characterised in each
2.2. Molecular structures
case by a
n
(CO) band which fell in the narrow range 1940e
(BeH) band was observed between 2481
1946 cmꢀ1, whilst the
n
Single crystals of 3a and 4bee were grown from CH2Cl2/hexane
(3a, 4b, 4c) or CH2Cl2/MeOH (4d, 4e). Plots of these molecules are
shown in Figs. 1e5, and crystallographic data and important bond
lengths and bond angles are summarised in the caption of Fig.1 and
Tables 1e3.
The metal centre in 3a exhibits a distorted octahedral geometry,
consistent with previous examples [28,46]. The vinyl ligand is co-
planar with the CO moiety (C(23)eRu(1)eC(1)eC(2) 9.7ꢂ),
and 2485 cmꢀ1. The 31P NMR spectra exhibited singlets between
49.4 and 51.3 ppm arising from the PPh3 ligand. The complexes
were further characterised by Atmospheric Solids Analysis Probe
(ASAP) ionisation mass spectrometry [54], which gave clean
spectra containing either the molecular ion, [M]þ, or the proton-
ated form, [M þ H]þ, and the structures confirmed by single
crystal X-ray diffraction studies.
Fig. 1. A plot of a molecule of 3a, showing the atom-labelling scheme. Thermal ellipsoids in this and all subsequent figures are plotted at the 50% probability level. Selected bond
ꢂ
ꢀ
lengths (A) and angles ( ): Ru(1)eP(1) 2.3539(5); Ru(1)eP(2) 2.3919(4); Ru(1)eP(3) 2.3657(5); Ru(1)eCl(1) 2.4617(5); Ru(1)eC(23) 1.8602(19); Ru(1)eC(1) 2.1165(15); C(1)eC(2)
1.339(2); C(2)eC(3) 1.480(2); N(1)eC(6) 1.422(2); N(1)eC(9) 1.408(2); N(1)eC(16) 1.433(2); P(1)eRu(1)eP(2) 95.73(2); P(1)eRu(1)eCl(1) 86.11(2); P(1)eRu(1)eC(23) 94.16(5);
P(1)eRu(1)eC(1) 82.37(4); P(1)eRu(1)eP(3) 164.31(2).

176
J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
Fig. 2. A plot of a molecule of 4b, showing the atom-labelling scheme.
Fig. 4. Plot of a molecule of 4d, showing the atom-labelling scheme.
a feature common to the vinyl complexes described here and
elsewhere, and commented upon in more detail below. The
nitrogen centre is essentially planar, with the sum of angles at N(1)
360ꢂ, confirming the sp2 nature of this atom. The planes of vinyl
and phenyl (C3eC8) groups are not parallel (torsion angle C1eC2e
C3eC4 is 24.1ꢂ) and aromatic rings around N1 atom adopt the usual
“propeller” configuration.
individual structures. The co-planar arrangement of the vinyl and
carbonyl ligands has been noted previously [43], and arises to maxi-
mise back-bonding interactions between the metal d-orbitals with
the vinyl and carbonyl p* systems [57]. This preferential bonding
situation that arises from a coplanar orientation of the carbonyl and
vinyl ligands results in a significant energy barrier to rotation about
the metal alkenyl bond, up to 10 kcal molꢀ1, which is significantly
higher than values found in simple organic alkene molecules, where
rotation is often less than 2 kcal molꢀ1 [58,59]. Although a simple
schematic MO description does not distinguish a preference for the
vinyl ligand cis or trans to the CO ligand, detailed NBO analysis on
related model systems suggests that the cis geometry is marginally
(<2 kcal molꢀ1) more stable [58]; steric effects may also play a role. It
Compounds 4bee crystallize in centrosymmetrical space groups
and therefore are racemic mixtures of two enantiomers. The Tpꢀ
anion acts as a facial tridentate ligand occupying three coordination
sites, and hence the ruthenium metal centre exhibits a distorted
octahedral geometry. Within the series 4bee, the RueCO
ꢀ
ꢀ
[1.8273(19)e1.833(3) A], RueP [2.3193(5)e2.3360(8) A] and Rue
ꢀ
C(1) [2.038(3)e2.0582(19) A] bond lengths are comparable with
those of related hydroruthenated compounds such as [Ru(CH]
ꢀ
is also possible to speculate that intra-molecular C(2)eH/
(carbonyl) interactions may augment the preference of coplanar cis-
p
CHC3H7)Cl(CO)(PPh3)2(Me2Hpz)] [RueCO; 1.79(1) A, RueP;
ꢀ
ꢀ
2.319(3) A, and RueCa; 2.05(1) A] [55] and [{RuCl(CO)(PPh3)2(Py)
ꢀ
ꢀ
orientation of vinyl and carbonyl ligands (the corresponding
CH]CH}3C6H3-1,3,5] [RueCO; 1.809(10) A, RueP; 2.397(2) A, and
RueCa; 2.050(8) A] [56]. There is little or no evidence for significant
ꢀ
ꢀ
distances H/middle of CO are in range 2.49e2.82 A).
quinoidal character within the phenylene portion of the molecule.
The strong trans influence of the s-vinyl ligand noted above also
2.3. Electrochemistry
causes an elongation of the RueN(5) distance. The vinyl ligand is
essentially planar, with the C(1)eC(2)eC(3)eC(4)/C(8) torsion angle
in the range 2.3e19.6ꢂ, although there are no obvious close inter-
molecular contacts that might account for the variation between
Despite the close relationships between Tpꢀ and Cpꢀ [60], and
the interest in the redox chemistry of both half-sandwich
Fig. 3. Plot of a molecule of 4c, showing the atom-labelling scheme.
Fig. 5. A plot of a molecule of 4e, showing the atom-labelling scheme.

J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
177
Table 1
Crystal data and structure refinement for compounds 3a, 4be4f.
Complex
3a
4b
4c
4d
4e
4f
Empirical formula
Formula weight (g molꢀ1
Crystal system
C32H47ClNOP3Ru
691.14
Triclinic
P ꢀ 1
C37H34BN6O2PRu
737.55
Orthorhombic
Pbca
15.1780(3)
18.1705(3)
24.3305(5)
90.00
90.00
90.00
6710.2(2)
8
1.460
C37H34BN6OPRu
721.55
Monoclinic
P 21/n
12.3553(4)
17.5258(6)
15.5575(5)
90.00
90.66(1)
90.00
C39H36BCl2N6O3PRu
850.49
Orthorhombic
Pca21
17.9655(9)
13.7346(7)
15.5579(9)
90.00
90.00
90.00
3838.9(4)
4
1.472
C36H31BN7O3PRu
752.53
Monoclinic
P21/n
12.2388(2)
17.7482(3)
15.5664(3)
90.00
90.36(10)
90.00
C37H31BN7OPRu
732.54
Monoclinic
P21/n
12.3271(4)
17.7540(5)
15.5549(4)
90
90.19(1)
90.0
)
Space group
ꢀ
a (A)
11.5356(3)
12.9757(4)
13.3499(4)
64.04(1)
70.43(1)
78.61(1)
1689.77(8)
2
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢂ)
(ꢂ)
(ꢂ)
3
ꢀ
Volume (A )
Z
3368.54(19)
4
1.423
3381.21(10)
4
1.478
3404.3(2)
4
1.429
rcalc (mg/m3)
1.358
0.710
m
(mmꢀ1
)
0.559
0.553
0.635
0.559
0.549
F(000)
Reflections collected
720
30,109
3024
98,899
1480
44,956
1736
30,441
1536
42,882
1496
38,474
Independent reflections/Rint
Data/restraints/parameters
Goodness-of-fit on F2
9862
9862/0/540
1.064
8512/0.0626
8512/0/569
1.069
9799/0.0607
9799/0/560
1.026
10,183/0.0273
10,183/1/483
1.047
8573/0.0727
8573/0/450
0.986
8972/0.0898
8972/0/437
0.976
Final R1 indices [I > 2
wR2 indices (all data)
s(I)]
0.0286
0.0344
0.0361
0.0990
0.0324
0.0820
0.0380
0.1069
0.0334
0.0847
0.0409
0.0809
complexes bearing unsaturated ligands [20] and five and six-
coordinate vinyl complexes [17], the redox chemistry of Ru(CH]
CHC6H4R-4)(CO)(PPh3)Tp systems seems to have been barely
explored. The six-coordinate Tpꢀ capped ruthenium vinyl
complexes 4aee all show one or two (4a) oxidation waves at
platinum working electrodes in CH2Cl2/0.1 M NBu4BF4 at potentials
that reflect the electronic properties of the aryl substituent
(Table 4), but with some signs of slow electron transfer and
chemical decomposition of the cations. Similar complications have
been noted previously for Ru(CH]CHR)Cl(CO)(PMe3)3 derivatives
[28]. Complex 4e also has a reduction wave, reversible in CH2Cl2,
which can be readily assigned to the reduction of the nitrophenyl
moiety. The significant influence of the aryl ring substituent on the
electrochemical potentials in the series of complexes 4aee indi-
cates that the aryl group is likely closely associated with the redox-
active orbitals. At a glassy carbon working electrode in NCMe/0.1 M
NBu4BF4 the electrochemical response was fully electrochemically
accompany the variation in redox state using spectroelec-
trochemical methods [61]. Metal-based oxidations usually result in
a shift in
n
(C^O) of wþ100 cmꢀ1, due to the substantial decrease in
metal-carbonyl back-bonding [62]. On oxidation of the complexes
4aee there is a shift in
n
(C^O) of ca. þ30e50 cmꢀ1 (Table 5), which
compares with the ca. þ20e65 cmꢀ1 that results from the oxidation
of closely related systems [Ru(CH]CHAr)Cl(CO)(PiPr3)2(L)]
(Ar ¼ Ph, pyrenyl; L ¼ 4-ethyl-isonicotinate, vacant coordination
site) and interpreted in terms of redox non-innocent vinyl ligands
[18]. In the present examples, the concept of a substantial degree of
ligand involvement in the redox process is supported by the small
shift in the
n
(BeH) of wþ15 cmꢀ1, which indicates that the Tpꢀ
ligand is hardly affected by the oxidation process. In addition, for 4d
the ester carbonyl also exhibited a small shift (ca. þ11 cmꢀ1
, n(CO)
1708e1719 cmꢀ1) which compares with the þ3e5 cmꢀ1 shift in the
isonicotinate ester bands upon oxidation of the five-coordinate
complexes [Ru(CH]CHR0)Cl(CO)(PiPr3)2(py)] (R0 ¼ But, Ph, 1-
pyrene, py ¼ 4-ethyl-isonicotinate) in which the ester reporting
group is connected via a pyridine ligand to the metal centre [18].
Consistent with the voltammetric data in CH2Cl2, a degree of
decomposition of the radical cations was evident in most
complexes, with a persistent band at ca. 1973 cmꢀ1 being formed
with a concomitant decrease in the intensity of the parent
spectrum on back-reduction. Attempts to probe the dication
[4a]2þ were compromised by rapid decomposition of the sample
at the platinum mini-grid working electrode of the spectroelec-
trochemical cell.
reversible at
n
¼ 100 mV/s, with linear dependence of peak current
on
n
1/2, peak-to-peak separation comparable with that of the
internal ferrocene reference, and peak current ratios of unity.
However, for consistency with the spectroelectrochemical experi-
ments, which employ a cell with a Pt micromesh working electrode,
voltammetric data from a Pt working electrode is reported here;
potential variations between the Pt and C electrodes are negligible.
2.4. IR spectroelectrochemistry
The n(CO) and n(BeH) bands provide convenient tools through
which to assess the structural and electronic changes that
Table 3
Selected bond angles and dihedral angles for 4bee.
Table 2
R
OMe
Me
CO2Me
NO2
Selected bond lengths for 4bee.
Complex
4b
4c
4d
4e
R
OMe
Me
CO2Me
NO2
C(9)eRu(1)eC(1)
C(9)eRu(1)eN(3)
C(1)eRu(1)eN(5)
C(9)eRu(1)eP(1)
C(1)eRu(1)eP(1)
N(1)eRu(1)eP(1)
C(2)eC(1)eRu(1)
C(1)eC(2)eC(3)
91.03(11)
174.77(9)
169.78(9)
92.61(8)
94.11(7)
175.47(6)
134.0(2)
127.0(3)
ꢀ8.53
86.52(8)
172.72(7)
171.96(7)
92.75(6)
91.92(5)
177.27(4)
132.10(15)
127.02(19)
ꢀ7.83
88.72(12)
174.54(12)
171.04(10)
93.37(10)
92.78(8)
174.19(7)
134.3(2)
125.2(3)
ꢀ5.52
87.42(10)
173.36(9)
171.91(8)
92.32(8)
92.46(6)
176.85(5)
131.89(19)
126.9(2)
7.89
Complex
4b
4c
4d
4e
Ru(1)eC(1)
Ru(1)eP(1)
Ru(1)eN(1)
Ru(1)eN(3)
Ru(1)eN(5)
C(1)eC(2)
C(2)eC(3)
Ru(1)eCO
CeO(1)
2.049(3)
2.0582(19)
2.3193(5)
2.1407(16)
2.1555(16)
2.1952(5)
1.342(3)
1.474(3)
1.8273(19)
1.153(2)
2.038(3)
2.3360(8)
2.121(2)
2.167(3)
2.179(2)
1.352(4)
1.472(4)
1.833(3)
1.154(4)
2.044(2)
2.3249(6)
2.125(2)
2.143(2)
2.190(2)
1.329(4)
1.470(4)
1.836(3)
1.149(3)
2.3315(6)
2.1368(19)
2.1504(19)
2.1879(18)
1.338(3)
1.466(3)
1.829(2)
1.154(3)
C(9)eRu(1)eC(1)eC(2)
Ru(1)eC(1)eC(2)eC(3)
C(1)eC(2)eC(3)eC(8)
ꢀ173.40
1.0
173.57
ꢀ176.29
ꢀ2.5
176.61
18.3
19.6

178
J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
Table 4
(torsion angles:
q
¼ COeRueCaeCb;
f
¼ CaeCbeCipsoeCortho, Fig. 6).
Electrochemical data for 4aee.a
For example, the Ca]Cb bond lengths in 4a0ee0 fall between 1.3504
ꢀ
and 1.3554 A, whilst the RueP bond length, which has been used as
Complex
R
E1/2/V
4ab
4bc
4c
N(C6H4CH3ꢀ4)2
0.00
0.14
0.24
0.40
0.51
a relatively sensitive structural probe of electron density at the
metal centre [67], falls in the small range 2.1423e2.1435 A. This
structural invariance in the RueP bond length likely reflects the
stronger back-bonding character of the vinyl p* system which
competes with the phosphine for electron-density from the same
ꢀ
OMe
Me
4d
CO2Me
NO2
4ed
a
Data acquired in 0.1 M NBu4BF4 in CH2Cl2 using a platinum working electrode,
platinum counter and reference electrodes at a scan rate of 100 mV sꢀ1 and refer-
enced to FcH/[FcH]þ ¼ 0 V reported for comparison with spectroelectrochemical
experiments conducted under similar conditions.
metal d-orbital. The computed and observed n(CO) frequencies also
display little variation across the series 4a0e4e0 and together these
structural and spectroscopic data suggest that there is little elec-
tronic influence of the ligand on the local electronic environment at
the metal centre.
b
A reversible oxidation was observed at E1/2 0.39 V attributed to the oxidation of
the amine moiety.
c
An irreversible oxidation was observed at Epa 0.64 V attributed to the oxidation
In general, the HOMO is delocalised over the metal, vinyl moiety
and substituent. However, in the case of 4a0 the HOMO is rather
more heavily weighted on the triarylamine fragment, which is
consistent with the low oxidation potentials of triarylamines [68],
and it is the HOMOe1 which offers character similar to the HOMO
in the other members of the series. Plots of the HOMO, LUMO and
LUMOþ1 for 4b0 which are representative of the key molecular
orbitals across the series are given in Fig. 7, whilst orbital energies
and composition of selected important frontier orbitals are sum-
marised in Table 7, with more complete lists given in the
Supporting information. In the neutral systems 4b0ee0, the metallic
contribution to the HOMO and HOMOe1 is modestly sensitive to
the nature of the substituent, with vinyl ligand contribution and
HOMO energy greater for those systems bearing electron-donating
substituents (4b, 4c). Similarly significant contributions (67e84%)
of the vinyl ligand to the HOMOs in complexes [Ru(CH]CHAr)
Cl(CO)(PMe3)2] (Ar ¼ Ph, Py) have been computed by Winter and
his team [18]. Thus, in each case, the HOMO is predominately
of the anisole moiety.
d
A reversible reduction was observed at E1/2 ꢀ1.72 V for the nitro moiety.
2.5. Electronic structure calculations
The use of DFT based calculations in support of electrochemical
and spectroscopic data to determine details of molecular electronic
structure is now firmly established [6,64], although correlation
problems continue to provide challenges for the design of appro-
priate functionals [65,66]. The computational models 4a0ee0 were
constructed using the same ligands as in the real complexes with
no symmetry constraints. The ‘prime’ nomenclature is used to
distinguish the computational and experimental systems. We have
found on previous occasions that B3LYP/3-21G* generally gives
computational results which are in good agreement with experi-
mentally determined structural and spectroscopic properties for
both ruthenium acetylide [20] and vinyl [28] complexes. However,
in the case of [4a0]n (n ¼ 0, þ1, þ2), [4b0]n (n ¼ 0, þ1), [4c0]n
(n ¼ 0, þ1), [4d0]n (n ¼ 0, þ1) and [4e0]n (n ¼ ꢀ1, 0, þ1), it proved
necessary to use the LANL2DZ basis set on Ru (3-21G* on all other
atoms) to obtain optimised structures free of imaginary frequen-
cies. There is very good agreement between the available crystal-
lographically determined structures of 4be4e and the DFT
optimised geometries, denoted 4a0e4e0 (Table 6), and also between
comprised of a RueCH]CHeAr p-type system and can be termed
a “metaleligand” (ML) orbital (Fig. 7, Table 7). The corresponding
vinyl ligand p* system features an appreciably smaller metal
contribution (Fig. 7, Table 7) and can be designated a “ligand” (L)
orbital. The energy of this p* orbital is also sensitive to the elec-
tronic nature of the aryl substituent, and comprises the LUMO for
4d0 and 4e0, LUMOþ4 for 4a0 and LUMOþ8 for 4b0 and 4c0. For 4a0,
4b0 and 4c0 the LUMO is essentially a phosphine s*-orbital, with
contributions from the metal centre.
spectroelectrochemically observed and calculated
(BeH) frequencies (Table 5), although the (BeH) values were
consistently over-estimated in the calculations.
n(C^O) and
n
n
This description of the electronic structure is further supported
by the UVeviseNIR spectra of 4aee. The UVeviseNIR spectrum of
each complex 4aee is characterised by an intense absorption
envelope which decreases in energy 4b > 4a > 4c [ 4d [ 4e
The computed structures 4a0ee0 are remarkably consistent, with
little variation in response to the electronic character of the vinyl
ligand substituent despite the high degree of conjugation between
the metal and aryl moiety suggested by the almost coplanar
arrangement of the vinyl ligand, phenylene ring and substituent
(Fig. 8, Table 8) and assigned to the vinyl ligand
pe
p* transition,
p* given the nature
which may perhaps be better described as d
p
e
Table 5
IR spectroelectrochemical data for [4aee]nþ (n ¼ 0, 1) in 0.1 M NBu4BF4 in CH2Cl2, and calculated frequencies from [4a0ee0]nþ (n ¼ 0, 1).a
R
Neutral
(C^O)/cmꢀ1
Cation
(C^O) /cmꢀ1
n
n
(BeH)/cmꢀ1
n
n
(BeH) /cmꢀ1
Dn(C^O)/cmꢀ1
Dn(BeH)/cmꢀ1
4a
4a0
4b
4b0
4c
N(C6H4CH3-4)2
OMe
1940
1939
1940
1938
1942
1939
1944
1940
1946
1942
2482
2550
2481
2550
2484
2551
2482
2552
2485
2555
1973
1961
1992
1974
1995
1980
1995
1984
1996
1990
2490
2573
2497
2581
2496
2583
2496
2446
2500
2589
33
22
52
36
53
42
51
45
50
49
8
23
16
32
12
33
14
34
15
35
b
Me
4c0
4dc
4d0
4e
CO2Me
NO2
d
4e0
a
A scaling factor of 0.98 applied to all caꢀlc1ulated frequencies [63].
b
c
LS-[4a0]2þ n(CO) 1988; (BeH) 2596 cm ; HS-[4a0]2þ n(CO) 1998; (BeH) 2598 cmꢀ1
n
n
.
Also
n
(COester): 4d 1708, [4d]þ 1719 cmꢀ1; [4d0] 1696; [4d0]D 1698 cmꢀ1
(BeH) 2531 cmꢀ1
.
d
[4e0]ꢀ n(CO) 1927;
n
.

J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
179
Table 6
Selection of critical bond lengths from the crystallographically determined structures of 4b, 4c, 4d and 4e, and the corresponding bond lengths from the optimised geometries
of the model systems [4a0]n (n ¼ 0, þ1, þ2), [4b0]n (n ¼ 0, þ1), [4c0]n (n ¼ 0, þ1), [4d0]n (n ¼ 0, þ1) and [4e0]n (n ¼ ꢀ1, 0, þ1).
RueCa
Ca ¼ Cb
CbeCipso
RueP
RueN1 (trans phosphine)
RueN3 (trans CO)
RueN5 (trans vinyl)
4a0
2.0696
2.0090
1.9579
2.0526
2.049(3)
2.0717
1.9953
2.0582(19)
2.0705
1.9944
2.038(3)
2.0655
1.9979
2.044(2)
2.0601
2.0045
2.0718
1.3513
1.3828
1.4180
1.3621
1.329(4)
1.3504
1.3871
1.342(3)
1.3505
1.3850
1.352(4)
1.3529
1.3824
1.338(3)
1.3554
1.3775
1.3596
1.4767
1.4361
1.4021
1.4694
1.470(4)
1.4786
1.4375
1.474(3)
1.4788
1.4439
1.472(4)
1.4736
1.4490
1.466(3)
1.4686
1.4549
1.4620
2.3742
2.4175
2.4564
2.4703
2.3249(6)
2.3769
2.4377
2.3193(5)
2.3773
2.4459
2.3360(8)
2.3795
2.4526
2.3315(6)
2.3835
2.4597
2.3774
2.1435
2.1490
2.1471
2.1431
2.125(2)
2.1423
2.1475
2.1407(16)
2.1423
2.1540
2.121(2)
2.1428
2.1455
2.1368(19)
2.1432
2.1448
2.1422
2.1814
2.1631
2.1470
2.1413
2.143(2)
2.1807
2.1577
2.1555(16)
2.1799
2.1540
2.167(3)
2.1778
2.1488
2.1504(19)
2.1768
2.1474
2.1797
2.2319
2.2142
2.1902
2.1642
2.190(2)
2.2338
2.2094
2.1952(15)
2.2335
2.2068
2.179(2)
2.2312
2.2022
2.1879(18)
2.2277
2.1955
2.2566
[4a0]þ
LS-[4a0]2þ
HS-[4a0]2þ
4b
4b0
[4b0]þ
4c
4c0
[4c0]þ
4d
4d0
[4d0]þ
4e
4e0
[4e0]þꢀ
[4e0]
of the molecular orbitals. In addition, 4a features a characteristic
N(p)eAr(p*) transition envelope near 31,850 cmꢀ1 [69]. These
suggestions are in agreement with the results of TD DFT calcula-
tions, the results of which are summarised in Table 8.
regarding the composition of the
b-LUSO, the spin density distri-
bution in [4a0]þ reinforces the concept that the triarylamine moiety
plays an important role in stabilising the charge generated after
oxidation.
The orbital characteristics described for the neutral systems are
largely retained upon oxidation (Fig. 9, Table 9), although the a-
LUSO is essentially comprised of the vinyl ligand p* system
The computational methods also allow clarification of the
nature of the electrochemically observed species [4a]2þ and [4e]ꢀ.
The low-spin (singlet) dication [4a0]2þ, is calculated to lie some
0.16 eV lower in energy than the high-spin (triplet) state. The
optimised geometries of LS- and HS-[4a0]2þ (Table 6) are conve-
niently represented by the limiting valence bond descriptions given
admixed with some metal character in each case, evidencing
a degree of electronic and structural relaxation on oxidation. The
HOSO is rather more metal in character (Table 9). In addition, the
metallic contribution to the -LUSO is generally somewhat greater
b-
b
than in the HOMþO of the corresponding neutral system, although in
the case of [4a0] there is a substantial contribution from the tri-
arylamine moiety to this orbital and the amine group clearly is
important in stabilising the charge in this rather delocalised
system. The structural differences between the neutral complexes
4a0ee0 and the radical cations [4a0ee0]þ reflect the composition and
nodal properties of the HOMO (Fig. 7, Table 7) in 4a0ee0 and
b-LUSO
in [4a0ee0]þ (Fig. 9, Table 9).
The calculated
those observed from the spectroelectrochemical experiments, and
the small increase in frequency of the (C^O) band upon oxidation
-LUSO. Spin
n(C^O) frequencies are in good agreement with
n
is consistent with small metal contribution to the
b
density calculations on the optimised geometries of [4a0ee0]þ
support these general conclusions, with the vinyl ligand support-
ing progressively more of the electron spin as the donating prop-
erties of the vinyl substituent increase (Fig. 10). As noted above
Fig. 6. A schematic representation of the torsion angles (ꢂ)
geometries 4a0ee0.
q
and
f
from the optimised
Fig. 7. Plots of the HOMO, LUMO and LUMOþ8 for 4b0. In this and the subsequent
figures, orbitals are plotted with contour values at ꢃ0.04 (e/bohr3)1/2
.

180
J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
Table 7
Table 8
Energy (eV) and composition (%) of selected frontier orbitals 4a0ee0.
Principal UVevis absorption bands [nmax/cmꢀ1 /Mꢀ1 cmꢀ1)] observed from 0.1 M
( 3
TBABF4 in CH2Cl2 solutions of [4aee]nþ (n ¼ 0, 1) and results of TD DFT calculations.
3
(eV)
þ0.13
ꢀ0.19 55
ꢀ0.20
%Tp %PPh3 %CO %Ru %CHCH %C6H4 %R
Complex
R
Wavenumber/cmꢀ1
,
TD DFT excitations/cmꢀ1
(oscillator strength) and
principal character
4a0 LUMOþ9
LUMOþ5
LUMOþ4
LUMOþ3
LUMO
2
0
21
38
64
85
1
0
15
0
4
1
0
7
2
6
8
0
1
13
5
1
17
19
10
1
31
8
1
25
9
88
0
9
2
0
[
3
/Mꢀ1 cmꢀ1
]
7
ꢀ0.39 11
4a
N(C6H4CH3ꢀ4)2 31,850 [27,530]
31,675 (f ¼ 0.2326)
HOMO / LUMOþ9
29,545 (f ¼ 0.3834)
HOMO / LUMOþ4
28,835 (f ¼ 0.2331)
HOMO / LUMOþ5
27,609 (f ¼ 0.1860)
HOMO / LUMOþ3
ꢀ0.76
ꢀ4.31
ꢀ5.10
4
1
5
HOMO
HOMOꢀ1
0
9
47
36
29,500 [32,300]
2
0
30
4b0 LUMOþ10 þ0.63
3
1
12
85
2
3
5
1
0
2
6
8
0
18
1
91
36
0
0
2
0
8
LUMOþ8
þ0.38 21
LUMO
ꢀ0.71
ꢀ4.47
4
3
HOMO
22
33
33
[4a]þ
20,530 [18,250]
8640 [20,350]
23,580 (f ¼ 0.2276)
4c0 LUMOþ8
LUMO
þ0.28 32
15
85
2
1
1
0
4
8
28
13
1
35
33
0
30
1
0
1
a
b
-HOSO / a-LUSO
-HOSO-17 / b-LUSO
ꢀ0.73
ꢀ4.64
4
4
9875 (f ¼ 0.5151)
HOMO
b
-HOSO / -LUSO
b
4d0 LUMOþ1
LUMO
ꢀ0.80
ꢀ0.91
ꢀ4.92
5
2
5
63
24
2
1
1
0
9
3
33
3
13
34
13
38
24
7
19
3
4b
OMe
33,560 [20,270]
35,644 (f ¼ 0.1791)
HOMO / LUMOþ8
HOMO / LUMOþ10
HOMO
4e0 LUMOþ1
LUMO
ꢀ0.98
ꢀ2.03
ꢀ5.21
5
0
6
82
0
2
2
0
0
10
1
37
1
7
32
0
28
20
0
64
3
[4b]þ
23,420 [13,200]
12,220 [6240]
27,226 (f ¼ 0.4696)
a
b
-HOSO / a-LUSO
-HOSO-17 / b-HOSO
HOMO
13,496 (f ¼ 0.1233)
b
b
-HOSO-5 /
b-LUSO
-HOSO / -LUSO
b
in Fig. 11. These simple descriptions are supported further by the
spin density distribution in the case of the open-shell system HS-
[4a0]2þ (Fig. 10). Thus, whilst the HS state is well described in terms
of localised Ru(III) and triarylamininum cations, the lower energy
LS state has a more delocalised electronic structure which would be
more in keeping with the description of the redox product in terms
of a doubly oxidised styrene, supported by the strongly electron-
donating {Ru(CO)(PPh3)Tp} and {N(C6H4Me-4)2} moieties. There
is little difference in the structures of 4e0 and [4e0]ꢀ (Table 6) and
analysis of the LUMO composition of 4e and spin density distri-
bution in [4e0]ꢀ suggests that electrochemical reduction of 4e can
be described entirely satisfactorily in terms of a NO2 based redox
event.
11,302(f ¼ 0.1397)
-HOSO / -LUSO
b
b
4c
CH3
32,900 [18,570]
36,144(f ¼ 0.2991)
HOMO / LUMOþ8
[4c]þ
24,390 [3270]
13,040 [1070]
27,771 (f ¼ 0.3614)
a
b
-HOSO / a-LUSO
-HOSO-17 / b-LUSO
13,198 (f ¼ 0.1311)
b
-HOSO / -LUSO
b
4d
CO2Me
27,930 [31,960]
29,606 (f ¼ 0.5414)
HOMO / LUMO
HOMO / LUMOþ1
In the UVeviseNIR spectroelectrochemical studies, oxidation of
4bee to [4bee]þ causes a shift of the d p* (or ML-LCT) transition
pe
[4d]þ
22,320 [2190]
13,120 [700]
25,500 (f ¼ 0.0537)
to lower energy by 5000e10,000 cmꢀ1, with a new transition in the
NIR region near 10,000 cmꢀ1 (1160e760 nm) (Fig. 8). These new,
low energy bands can largely be assigned to excitations from the
a
b
-HOSO / a-LUSO
-HOSO-19 / b-LUSO
12,744 (f ¼ 0.1267)
b
-HOSO / -LUSO
b
b
-HOSO to the b-LUSO and therefore have more MLCT character.
4e
NO2
22,830 [28,750]
23,757 (f ¼ 0.4830)
HOMO/LUMO
[4e]þ
16,050 [4020]
12,800 [1070]
14,085 (f ¼ 0.0940)
b
-HOSO-3 / b-LUSO
12,230 (f ¼ 0.0695)
b
b
-HOSO /
-HOSO-1 /
b
-LUSO
-LUSO
b
With the exception of [4e]þ, the visible band corresponds to the
-HOSO to -LUSO excitation, admixed with excitations involving
a lower lying -spin orbital and -LUSO of similar composition
(Tables 8 and 9). The absorption band therefore arises from exci-
a
a
b
b
tations with essentially the same dpe
p* (ML-LCT) character as the
UV band in the neutral species. For [4e]þ, which carries the most
electron withdrawing substituent, the visible band is much lower in
energy, weak, and has much more significant MLCTcharacter. In the
case of oxidation of 4a to [4a]þ both ML-LCT and N(p)eAr(p*
)
Fig. 8. The UVeviseNIR spectra of 4b and [4b]þ obtained by spectroelectrochemical
methods (CH2Cl2/0.1 M NBu4BF4).
transitions collapsed, reflecting the mixed metal/nitrogen chaþr-
acter of the HOMO in 4a0 and the -HOSO and LUSO in [4a0] .
a- and b

J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
181
Fig. 9. Plots of the (a) a-HOSO (b) a-LUSO (c) b-HOSO and (d) b .
-LUSO for [4d0]þ
3. Conclusions
Tpꢀ supported complexes. The involvement of the vinyl ligand in
the redox-active orbitals is reflected in the sensitivity of the
oxidation potential E1/2 to the electronic character of the vinyl
ligand substituent, and the relatively small positive shift of the
The studies described above have shown that the vinyl ligand in
the complexes [Ru(CH]CHC6H4R-4)(CO)(PPh3)Tp]nþ (n ¼ 0, 1) is
significantly involved in both the HOMO of the neutral complexes
n
(C^O) frequencies that accompany oxidation of 4aee, which is
and the
b
-LUSO of the monocations. Thus, the suspicions con-
also reproduced in frequency calculations. UVeviseNIR spec-
troelectrochemistry, spin density calculations and analysis of the
frontier molecular and spin orbitals are also consistent with this
description in terms of a significant contribution of the vinyl ligand
to the oxidation event. The relative contribution of metal atom and
vinyl ligand to the frontier orbitals is sensitive to the vinyl ligand
substituent, permitting a degree of tuning of the electronic
structure.
cerning the nature of redox products derived from five- and six-
coordinate vinyl ligands raised by Winter are confirmed here for
Table 9
Energy (eV) and composition (%) of selected spin orbitals [4a0e4e0]þ.
3 (eV)
%Tp %PPh3 %CO %Ru %CH]CH %C6H4 %R
[4a0]þ
a
b
a
b
b
-LUSO
-LUSO
-HOSO
-HOSO
ꢀ3.45
ꢀ6.05
ꢀ7.35
2
2
3
3
1
1
1
11
1
0
0
0
1
4
18
13
29
7
29
23
19
8
50
29
29
13
10
12
26
36
39
21
4. Experimental
ꢀ7.70 10
-HOSO-17 ꢀ9.59 45
5
4.1. General conditions
[4b0]þ
a
b
a
b
b
b
-LUSO
-LUSO
-HOSO
-HOSO
-HOSO-5
-HOSO-17 ꢀ10.64 33
ꢀ3.70
ꢀ6.49
ꢀ8.08
2
4
4
7
2
2
3
37
3
1
0
0
1
3
2
5
31
16
27
28
21
39
30
26
8
3
31
42
27
40
24
5
4
6
12
10
3
All reactions were carried out under an atmosphere of nitrogen,
using standard Schlenk techniques. Reaction solvents were purified
and dried using an Inovative Technology SPS-400, and degassed
before use. No special precautions were taken to exclude air during
the workup. Compounds RuHCl(CO)(PPh3)3 [70], 1d and 1e [71]
were prepared by literature methods. 1a was prepared by desily-
lation of Me3SiC^CC6H4N(C6H4Me-4)2 [72]. Other reagents were
purchased (SigmaeAldrich) and used as received.
ꢀ8.58 28
ꢀ9.29 22
7
4
[4c0]þ
[4d0]þ
[4e0]þ
a
b
a
b
b
-LUSO
-LUSO
-HOSO
-HOSO
ꢀ3.81
ꢀ6.65
ꢀ8.39
3
5
6
8
2
2
5
11
2
0
0
1
2
5
37
17
22
18
39
30
29
11
30
42
24
43
24
13
1
1
3
2
2
ꢀ8.84 35
The NMR spectra were recorded on a 400 MHz Bruker Avance
spectrometer from deuterated chloroform solutions and referenced
-HOSO-17 ꢀ10.87 24
against residual protio solvent resonances (CHCl3: 1H 7.26 ppm; 13
C
a
b
a
b
b
-LUSO
-LUSO
-HOSO
-HOSO
ꢀ4.19
ꢀ6.84
ꢀ8.64
2
6
7
2
2
2
7
14
1
0
0
1
2
4
41
17
19
17
31
28
30
13
28
48
20
39
21
14
12
2
4
2
3
77.0 ppm) or external phosphoric acid. In 13C NMR assignments, the
carbons on the aromatic ring are labelled C1eC4 from the ethynyl
substituent, and C5eC8 for the tolyl ring carbons in 2a, 3a and 4a
from the N centre. The carbons on the phosphine ligands are labelled
Ci, Co, Cm, Cp relative to the P centre. IR spectra were recorded using
a Thermo 6700 spectrometer from CH2Cl2 solutions in a cell fitted
with CaF2 windows. MALDI-mass spectra of organometallic
complexes were recorded using Autoflex II TOF/TOF mass spec-
trometer (Bruker Daltonik, GmbH) equipped with a 337 nm laser.
Samples in CH2Cl2 (1 mg/ml) were mixed with a matrix solution of
ꢀ9.02 38
-HOSO-19 ꢀ11.01 22
a
b
a
b
b
b
-LUSO
ꢀ4.92
ꢀ7.13
1
8
0
2
3
9
14
74
0
0
0
1
3
1
2
46
18
19
20
6
13
25
31
11
4
34
16
35
12
4
49
3
3
1
0
-LUSO
-HOSO
-HOSO
-HOSO-1
-HOSO-3
ꢀ9.00 10
ꢀ9.28 46
ꢀ9.32 55
ꢀ9.50 12
3
4
0

182
J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
Fig. 10. A summary of the spin density distribution in [4a0ee0]þ and HS-[4a0]2þ
.
trans-2-[3-(40-tert-butylphenyl)-2-methyl-2-propenylidene]malo-
nonitrile (DCTB) in a 1:9 ratio, with 1 l of mixture spotted onto
Hartl design [74], from CH2Cl2 solutions containing 0.1 M NBu4BF4
electrolyte. The cell was fitted into the sample compartment of the
Nicolet Avatar, Thermo 6700, Thermo Array UVeVis or Perkine
Elmer Lambda 900 spectrophotometer and electrolysis in the cell
was performed with a PGSTAT-30 potentiostat.
m
a metal target prior to exposure to the MALDI ionization source.
Accurate mass measurements were recorded with a Xevo QToF mass
spectrometer (Waters Ltd, UK) equipped with an Agilent 7890 GC
(Agilent Technologies UK Ltd, UK). Exact mass measurements uti-
lised a lock-mass correction to provide <3 mDa precision. Exact
mass measurement used Elemental Composition version 4.0
embedded within MassLynx 4.1 (Waters Ltd, UK).
The single-crystal X-ray data were collected at 120.0(2)K on
a Bruker SMART-CCD 1K (compound 4f) and Bruker SMART CCD
ꢀ
6000 (all other compounds) diffractometers (
u
l
Mo-K
a
,
l
¼ 0.71073 A,
-scan, 0.3ꢂ/frame) equipped with Cryostream (OxfordCryosys-
Electrochemical analyses were carried out using an EcoChemie
Autolab PG-STAT 30 potentiostat, with platinum working, platinum
counter and platinum pseudo reference electrodes, from solutions
tems) open-flow nitrogen cryostat. The data for 4be4e were cor-
rected for absorption using SADABS (4b and 4d) and face-indexed
numerical absorption correction procedures. The structures were
solved by direct method and refined by full-matrix least squares on
F2 for all data using SHELXTL [75] and OLEX2 [76] software. All non-
hydrogen atoms were refined with anisotropic displacement
parameters, H-atoms were located on the difference map and
refined isotropically in structures 3a, 4b and 4c, while in the rest of
the structures the hydrogen atoms were placed in calculated posi-
tions and refined in riding mode. The crystallographic and refine-
ment parameters are given in Supporting information.
in CH2Cl2 containing 0.1 NBu4BF4,
n
¼ 100e800 mV sꢀ1. All redox
potentials are reported with reference to an internal standard of the
ferrocene/ferrocenium couple (FcH/FcHþ ¼ 0.0 V) [73]. Spec-
troelectrochemical measurements were made in an OTTLE cell of
4.2. Syntheses
4.2.1. Preparation of Ru{CH]CHC6H4N(C6H4Me-4)2-4}Cl(CO)(PPh3)2
(2a)
To a suspension of RuHCl(CO)(PPh3)3 (0.20 g, 0.210 mmol) in dry
CH2Cl2 (8 ml) was added (MeC6H4)2N(C6H4C^CH) (0.08 g,
0.250 mmol). The reaction was stirred for 40 min after which the
solvent was removed. Addition of hexane (6 ml) to the red residue
dissolved in CH2Cl2 (1 ml) led to the formation of a pink powder. A
red powder was produced from CH2Cl2 (2 ml) and methanol (10 ml)
and dried under vacuum (0.16 g, 79%). Precipitation by CH2Cl2 and
diethylether gave the analytically pure sample (67 mg, 22%). 1H
NMR:
d
2.30 (s, 6H, CH3), 5.54 (d, 3JHH ¼ 13 Hz, RuCH]CH), 6.62 (d,
3JHH ¼ 8 Hz, Ar), 6.80 (d, 3JHH ¼ 8 Hz, Ar), 6.96 (d, 3JHH ¼ 8 Hz, 4H,
3
AreMe), 7.04 (d, JHH ¼ 8 Hz, 4H, AreCH3), 7.35e7.58 (m, 30H,
PPh3), 8.22 (dt, 3JHH ¼ 13 and 4JHP ¼ 2 Hz, 1H, RuCH]CH). 13C NMR:
d
20.9 (s, Me), 123.2 (C2/3), 124.3 (C6/7), 125.2 (C2/13), 128.5 (t,
3
0
0
JCP ¼ 5 Hz, Cm/m ), 129.9 (C6/7), 130.3 (s, Cp/p ), 132.0 (d, JCP ¼ 16 Hz,
2
0
0
Ci/i ), 132.2 (s, C8), 133.4 (s, C4), 134.4 (t, JCP ¼ 5 Hz, Co/o ), 135.4 (t,
4JCP ¼ 3 Hz, Rub), 144.2 (t, JCP ¼ 12 Hz, Rua), 144.9 (s, C1), 145.7 (s,
3
C5), 201.8 (unresolved, CO). 31P NMR:
d 29.5. IR (CH2Cl2): n(CO)
1932 cmꢀ1. MALDI(þ)-MS: 987.2 [M]þ.
4.2.2. Preparation of Ru{CH]CHC6H4N(C6H4Me-4)2-4}Cl(CO)(PMe3)3
(3a)
To a suspension of RuHCl(CO)(PPh3)3 (0.10 g, 0.105 mmol) in dry
CH2Cl2 was added (MeC6H4)2N(C6H4C^CH) (0.03 g, 0.105 mmol).
The reaction was stirred for 30 min and then PMe3 was added
Fig. 11. Valence bond descriptions of LS- and HS-[4a0]2þ
.

J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
183
(0.07 ml, 0.630 mmol) and the reaction stirred for a further 12 h.
The solvent was removed via Schlenk techniques and the resultant
oil triturated with hexane to produce a light yellow powder. Puri-
fication by preparative TLC using hexane and acetone (70:30)
produced a white powder (0.05 g, 67%). Crystallisation from CH2Cl2
7.68e7.71 (m, 3H, 3ꢄ Tp), 7.97 (dd, 3JHH ¼ 17 Hz and 3JHP ¼ 4 Hz, 1H,
RuCH]CH). 13C NMR:
d
55.7 (s, OMe), 105.4 (d, J ¼ 3 Hz, Tp), 105.5
3
0
(s, 2ꢄ Tp), 113.9 (s, C3), 125.5 (s, C2), 128.2 (d, JCP ¼ 9 Hz, Cm/m ),
4
1
0
0
130.0 (d, JCP ¼ 2 Hz, Cp/p ), 133.4 (d, JCP ¼ 42 Hz, Ci/i ), 134.4 (d,
2
0
JCP ¼ 10 Hz, Co/o ), 134.7 (d, J ¼ 2 Hz, Tp), 135.2 (s, Tp), 135.5 (s, Tp),
layered with hexane by slow diffusion gave crystals suitable for X-
135.8 (s, Cb), 136.1 (s, C1), 143.0 (s, Tp), 143.1 (s, Tp), 144.3 (s, Tp),
4
ray diffraction. 1H NMR:
d
1.40 (t, JHH ¼ 4 Hz, 18H, PMe3), 1.47 (d,
156.8 (s, C4),158.4 (d, 2JCP ¼ 14 Hz, Ca), 207.1 (d, 2JCP ¼ 17 Hz, CO). 31
P
4JHH ¼ 8 Hz, 9H, PMe3), 2.29 (s, 6H, Me), 6.47e6.53 (unresolved ddt,
1H RuCH]CH), 6.93 (d, 3JCP ¼ 8 Hz, 2H, Ar), 6.98 (d, 3JCP ¼ 8 Hz, 4H,
Ar), 7.03 (d, 3JCP ¼ 8 Hz, 4H, Ar), 7.17 (d, 3JCP ¼ 8 Hz, 2H, Ar), 7.87e
7.94 (ddt, 3JHH ¼ 20 Hz, 3JHꢀP(trans) ¼ 8 Hz, 3JHP ¼ 4 Hz, 1H, RuCH]
NMR:
1940,
d
51.3. MALDI(þ)-MS 738.2 [M þ H]þ. IR (CH2Cl2):
n(C^O)
n
(BeH) 2479 cmꢀ1. HR ASAP MS (m/z): 732.1760 [M þ H]þ
C37H35BN6O2PRu requires 732.1764.
CH). 13C NMR:
d
17.0 (td, 1JCP ¼ 15 and 3JCP ¼ 3 Hz, PMe3), 20.5 (dt,
4.2.5. Preparation of [{Ru(CO)(PPh3)Tp}(CH]CHC6H4Me-4)] (4c)
The synthesis and workup are similar to 2, with 1-ethynyl-4-
methoxybenzene replaced by p-tolylacetylene. A pale yellow
powder was collected by filtration and dried under vacuum
(0.051 g, 64%). Crystals suitable for X-ray diffraction were obtained
from the slow diffusion of hexane into a CH2Cl2 solution. 1H NMR:
1JCP ¼ 20 Hz, 3JCP ¼ 3 Hz, PMe3), 21.1 (s, Me), 124.1 (s, C6/7), 124.2 (s,
C2/3), 125.3 (s, C2/3), 130.0 (s, C6/7), 131.8 (s, C8), 134.6 (t, 3JCP ¼ 4 Hz,
Cb),136.8 (dt, 4JCP (trans) ¼ 8 and 4JCP ¼ 3 Hz, C1),144.7 (s, C4),146.1 (s,
2
2
C5), 163.3 (dt, JCP
¼ 77 Hz, JCP ¼ 18 Hz, Ca), 202.8 (q,
(trans)
2JCP ¼ 12 Hz, CO). 31P NMR:
d
ꢀ6.82 (d, J ¼ 23 Hz, PMe3), ꢀ18.63 (t,
J ¼ 23 Hz, PMe3). IR (CH2Cl2):
n
(CO) 1919 cmꢀ1. MALDI(þ)-MS: 615.1
d
2.30 (s, 3H, CH3), 5.90 (t, 3JHH ¼ 2 Hz, 1H, Tp), 5.92 (t, 3JHH ¼ 2 Hz,
[M ꢀ PMe3]þ, 587.1 [M ꢀ PMe3 ꢀ CO]þ.
1H, Tp), 6.05 (t, 3JHH ¼ 2 Hz, 1H, Tp), 6.36 (d, 3JHH ¼ 17 Hz, 1H, Rue
CH]CH), 6.78 (dd, 3JHH ¼ 12 and 3JHP ¼ 2 Hz, 2H, 2ꢄ Tp), 7.01e7.13
(m, 10H, 6H PPh3, 4H C6H4), 7.19e7.24 (m, 6H, PPh3), 7.33e7.37 (m,
3H, PPh3), 7.55 (unresolved t, 1H, Tp), 7.67e7.70 (m, 3H, 3ꢄ Tp), 8.14
4.2.3. Preparation of [{Ru(CO)(PPh3)Tp}(CH]CHC6H4N(C6H4Me)2)]
(4a)
To a suspension of RuHCl(CO)(PPh3)3 (0.30 g, 0.315 mmol) in dry
CH2Cl2 (10 ml) was added (MeC6H4)2N(C6H4C^CH) (0.11 g,
0.377 mmol). The reaction was allowed to stir for 30 min and then
KTp (0.16 g, 0.631 mmol) was added. After 18 h, the yellow green
solution was filtered through Celite, and the solvent removed. The
residue was redissolved in the minimum amount of CH2Cl2 (1 ml)
and methanol (8 ml) was added to produce a yellow precipitate.
Purification by preparative TLC using CH2Cl2 and hexane (35:65)
(dd, 3JHH ¼ 17 Hz and 3JHP ¼ 4 Hz,1H, RuCH]CH). 13C NMR:
d 21.3 (s,
CH3), 105.0 (d, J ¼ 3 Hz, Tp), 105.1 (s, 2ꢄ Tp), 124.3 (s, C2), 127.9 (d,
2
4
0
0
JCP ¼ 9 Hz, Cm/m ), 128.7 (s, C3), 129.6 (d, JCP ¼ 2 Hz, Cp/p ), 132.9 (s,
C4), 133.0 (d, 1JCP ¼ 42 Hz, Ci/i ), 134.0 (d, JCP ¼ 9 Hz, Co/o ), 134.4 (d,
3
0
0
J ¼ 3 Hz, Tp), 134.8 (s, Tp), 135.1 (s, Tp), 136.5 (s, Cb), 139.1 (s, C1),
2
142.6 (s, Tp), 142.7 (s, Tp), 143.9 (s, Tp), 160.0 (d, JCP ¼ 14 Hz, Ca),
206.7 (d, JCP ¼ 15 Hz, CO). 31P NMR:
d
50.6. MALDI(þ)-MS (m/z):
2
722.2 [M þ H]þ. IR (CH2Cl2):
n(C^O) 1942, n
(BeH) 2481 cmꢀ1. HR
gave a light yellow powder (0.60 g, 21%). 1H NMR:
d
2.31 (s, 6H, Me),
ASAP MS (m/z) 715.1735 [M] C37H34BN6OPRu requires 715.1737.
5.92 (t, 3JHH ¼ 2 Hz, Tp), 5.91 (t, 3JHH ¼ 2 Hz, Tp), 6.09 (unresolved t,
1H, Tp), 6.36 (d, 1H, 3JHH ¼ 16 Hz, RuCH]CH), 6.80 (dd, 3JHH ¼ 8 and
4JHP ¼ 4 Hz, 2H, 2ꢄ Tp), 6.94 (d, 3JHH ¼ 8 Hz, 2H, Ar), 6.99 (m, 10H,
2H Ar and 8H Ar0), 7.10e7.15 (m, 6H, PPh3), 7.21e7.26 (m, 6H, PPh3),
7.34e7.38 (m, 3H, PPh3), 7.58 (unresolved triplet, 1H, Tp), 7.70 (dd,
4.2.6. Preparation of [{Ru(CO)(PPh3)Tp}(CH]CHC6H4CO2Me-4)]
(4d)
The synthesis and workup are similar to 2, with 1-ethynyl-4-
methoxybenzene replaced by methyl 4-ethynylbenzoate. A light
green powder was produced (0.134 g, 56%). Crystals suitable for X-
ray diffraction were obtained from the slow diffusion of methanol
4
3JHH ¼ 17 and JHP ¼ 2 Hz, 2H, 2ꢄ Tp), 7.34 (m, 1H, Tp), 8.08 (dd,
3JHH ¼ 16 and 3JHP ¼ 4 Hz, 1H, RuCH]CH). 13C NMR:
d 21.1 (s, Me),
105.2 (d, J ¼ 2 Hz, Tp), 105.3 (s, Tp),105.3 (s, Tp),123.7 (s, C6/7), 124.5
into a CH2Cl2 solution. 1H NMR:
d 3.88 (s, 3H, OCH3), 5.91 (t,
3
(s, C2/3), 125.1 (s, C2/3), 128.0 (d, JCP ¼ 9 Hz, Cm/m ), 129.7 (s, C6/7),
3JHH ¼ 2 Hz, 1H, Tp), 5.94 (t, 3JHH ¼ 2 Hz, 1H, Tp), 6.07 (unresolved t,
0
1
129.8 (d, 4JCP ¼ 3 Hz, Cp/p ), 131.4 (s, C8), 133.1 (d, JCP ¼ 44 Hz, Ci/i ),
1H, Tp), 6.48 (d, 3JHH ¼ 17 Hz, 1H, RuCH]CH), 6.80 (dd, 3JHH ¼ 8 Hz
0
0
134.2 (d, 2JCP ¼ 9 Hz, Co/o ), 134.5 (d, J ¼ 3 Hz, Tp), 135.0 (s, Tp), 135.3
and JHP ¼ 2 Hz, 2H, 2ꢄ Tp), 7.04e7.09 (m, 6H, PPh3), 7.13 (d,
3
0
(s, Tp), 136.2 (s, Cb), 137.0 (s, C1), 142.8 (s, Tp), 142.9 (s, Tp), 144.0 (s,
J ¼ 8 Hz, 2H, C6H4), 7.18e7.23 (m, 6H, PPh3), 7.31e7.35 (m, 3H, PPh3),
2
Tp), 144.1 (s, C4), 146.1 (s, C5), 160.5 (d, JCP ¼ 12 Hz, Ca), 206.9 (d,
7.52 (unresolved t, 1H, Tp), 7.60 (d, 3JHH ¼ 2 Hz, 1H, Tp), 7.71 (d.o.d,
2JCP ¼ 17 Hz, CO). 31P NMR:
d
49.4. IR (CH2Cl2):
n
(CO) 1940,
n
(BH)
3JHH ¼ 8 Hz and JHP ¼ 2 Hz, 2H, 2ꢄ Tp), 7.87 (d, JHH ¼ 8 Hz, 2H,
3
3
2482 cmꢀ1
.
MALDI(þ)-MS: 903.2 [M]þ. HR ASAP MS (m/z):
C6H4), 8.68 (dd, JHH ¼ 17 Hz and JHP ¼ 4 Hz, 1H, RuCH]CH). 13
C
3
3
897.2664 C50H46BN7OPRu requires 897.2707.
NMR:
d
52.0 (s, OMe), 105.5 (d, J ¼ 2 Hz, Tp), 105.6 (s, Tp), 105.7 (s,
Tp), 124.2 (s, C2), 125.0 (s, C4), 128.3 (d, 2JCP ¼ 10 Hz, Cm/m ), 130.1 (s,
0
1
C3), 130.2 (d, 4JCP ¼ 2 Hz, Cp/p ), 133.0 (d, JCP ¼ 43 Hz, Ci/i ), 134.3 (d,
0
0
4.2.4. Preparation of [{Ru(CO)(PPh3)(Tp)}(CH]CHC6H4OMe-4)]
(4b)
3
0
JCP ¼ 10 Hz, Co/o ), 134.9 (d, J ¼ 2 Hz, Tp), 135.3 (s, Tp), 135.6 (s, Tp),
To a suspension of RuHCl(CO)(PPh3)3 (0.100 g, 0.105 mmol) in
CH2Cl2 (6 ml) was added 1-ethynyl-4-methoxybenzene (0.07 ml,
0.524 mmol). The solution turned red and was stirred for 30 min.
KTp (0.080 g, 0.315 mmol) was added and the solution turned green
over the course of an hour. The solution was then filtered through
Celite and the solvent removed. The residual solid was re-dissolved
in CH2Cl2 (2 ml), hexane was added (4 ml) and some solvent
removed. A light green powder was collected by filtration and dried
under vacuum (0.036 g, 43%). Crystals suitable for X-ray diffraction
136.7 (s, Cb), 142.9 (s, Tp), 143.0 (s, Tp), 144.3 (s, Tp), 145.5 (s, C1),
2
168.0 (s, CO of ligand), 171.3 (d, JCP ¼ 13 Hz, Ca), 206.8 (d,
2JCP ¼ 16 Hz, CO). 31P NMR:
d
50.9. MALDI(þ)-MS (m/z): 766.2
[M þ H]þ. IR (CH2Cl2):
n(C^O) 1940, n
(BeH) 2483 cmꢀ1. HR ASAP
MS (m/z): 760.1742 [M þ H]þ C38H34BN6O3PRu requires 760.1714.
4.2.7. Preparation of [{Ru(CO)(PPh3)Tp}(CH]CHC6H4NO2-4)] (4e)
The synthesis and workup are similar to 2, with 1-ethynyl-4-
methoxybenzene replaced by 1-ethynyl-4-nitrobenzene. An
orange powder was produced (0.152 g, 64%). Crystals suitable for X-
ray diffraction were obtained from the slow diffusion of methanol
were obtained from the slow diffusion of hexane into a solution of
3
CH2Cl2. 1H NMR:
d
3.78 (s, 3H, OCH3), 5.89 (t, JHH ¼ 2 Hz, 1H, Tp),
3
5.91 (t, JHH ¼ 2 Hz, 1H, Tp), 6.05 (unresolved t, 1H, Tp), 6.31 (d,
3JHH ¼ 17 Hz, 1H, RueCH]CH), 6.78e6.80 (m, 4H, 2H Tp and 2H
C6H4), 7.08e7.14 (m, 8H, 6H PPh3 and 2H C6H4), 7.20e7.23 (m, 6H,
PPh3), 7.33e7.36 (m, 3H, PPh3), 7.56 (unresolved triplet, 1H, Tp),
into a CH2Cl2 solution. 1H NMR:
d
5.93 (t, 3JHH ¼ 2 Hz, 1H, Tp), 5.96
3
(t, JHH ¼ 2 Hz, 1H, Tp), 6.08 (unresolved t, 1H, Tp), 6.54 (d,
3JHH ¼ 17 Hz, 1H, RueCH]CH), 6.81 (dd, JHH ¼ 16 Hz and
3
3JHP ¼ 2 Hz, 2H, 2ꢄ Tp), 7.03e7.07 (m, 6H, PPh3), 7.13 (d, 3JHH ¼ 9 Hz,

184
J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
[15] M.A. Fox, J.D. Farmer, R.L. Roberts, M.G. Humphrey, P.J. Low, Organometallics
28 (2009) 5266.
[16] N. Gauthier, N. Tchouar, F. Justaud, G. Argouarch, M.P. Cifuentes, L. Toupet,
D. Touchard, J.-F. Halet, S. Rigaut, M.G. Humphrey, K. Costuas, F. Paul,
Organometallics 28 (2009) 2253.
[17] P. Muecke, M. Linseis, S. Zalis, R.F. Winter, Inorg. Chim. Acta 374 (2011) 36.
[18] J. Maurer, M. Linseis, B. Sarkar, B. Schwederski, M. Niemeyer, W. Kaim, S. Zalis,
C. Anson, M. Zabel, R.F. Winter, J. Am. Chem. Soc. 130 (2008) 259.
[19] W.M. Khairul, M.A. Fox, P.A. Schauer, D. Albesa-Jove, D.S. Yufit, J.A.K. Howard,
P.J. Low, Inorg. Chim. Acta 374 (2011) 461.
[20] M.A. Fox, R.L. Roberts, W.M. Khairul, F. Hartl, P.J. Low, J. Organomet. Chem. 692
(2007) 3277.
[21] J. Maurer, B. Sarkar, B. Schwederski, W. Kaim, R.F. Winter, S. Zális, Organo-
metallics 25 (2006) 3701.
[22] E. Wuttke, F. Pevny, Y.-M. Hervault, L. Norel, M. Drescher, R.F. Winter,
S. Rigaut, Inorg. Chem. 51 (2012) 1902.
[23] F. Pevny, E. Di Piazza, L. Norel, M. Drescher, R.F. Winter, S. Rigaut, Organo-
metallics 29 (2010) 5912.
[24] K. Costuas, S. Rigaut, Dalton Trans. 40 (2011) 5643.
[25] A. Klein, O. Lavastre, J. Fiedler, Organometallics 25 (2006) 635.
[26] D.J. Armitt, M.I. Bruce, M. Gaudio, N.N. Zaitseva, B.W. Skelton, A.H. White, B. Le
Guennic, J.-F. Halet, M.A. Fox, R.L. Roberts, F. Hartl, P.J. Low, Dalton Trans.
(2008) 6763.
[27] M.A. Fox, B. Le Guennic, R.L. Roberts, D.A. Brue, D.S. Yufit, J.A.K. Howard,
G. Manca, J.-F. Halet, F. Hartl, P.J. Low, J. Am. Chem. Soc. 133 (2011) 18433.
[28] W.Y. Man, J.-L. Xia, N.J. Brown, J.D. Farmer, D.S. Yufit, J.A.K. Howard, S.H. Liu,
P.J. Low, Organometallics 30 (2011) 1852.
[29] A.F. Hill, in: D.E. Shriver, M.I. Bruce (Eds.), Comprehensive Organometallic
Chemistry II, vol. 7, Pergamon, Oxford, 1995, pp. 399e411.
[30] H. Werner, M.A. Esteruelas, H. Otto, Organometallics 5 (1986) 2295.
[31] H. Werner, U. Meyer, K. Peters, H.G. von Schnering, Chem. Ber. 122 (1989)
2089.
2H, C6H4), 7.19e7.24 (m, 6H, PPh3), 7.34e7.38 (m, 3H, PPh3), 7.59
(unresolved m, 2H, Tp), 7.72 (dd, 3JHH ¼ 12 Hz and 3JHP ¼ 2 Hz, 2H,
2ꢄ Tp), 8.06 (d, 3JHH ¼ 12 Hz, 2H, C6H4), 9.04 (dd, 3JHH ¼ 17 Hz and
3JHP ¼ 4 Hz, 1H, RuCH]CH). 13C NMR:
105.6 (d, J ¼ 3 Hz, Tp), 105.7
d
(s, Tp), 105.8 (s, Tp), 124.3 (s, C2), 124.5 (s, C3), 128.4 (d, 2JCP ¼ 10 Hz,
4
1
0
0
0
Cm/m ), 130.0 (d, JCP ¼ 2 Hz, Cp/p ), 132.7 (d, JCP ¼ 44 Hz, Ci/i ), 134.2
(d, 3JCP ¼ 10 Hz, Co/o ), 135.1 (d, JCP ¼ 2 Hz, Tp),135.5 (s, Tp),135.7 (s,
3
0
Tp), 136.0 (s, Cb), 142.9 (d, J ¼ 3 Hz, Tp), 144.0 (s, Tp), 144.4 (s, Tp),
146.6 (s, C1), 179.2 (d, 2JCP ¼ 12 Hz, Ca), 206.5 (d, 2JCP ¼ 16 Hz, CO).
*C1 not observed. 31P NMR:
d
50.7. MALDI(þ)-MS 753.10 [M þ H]þ.
IR (CH2Cl2): n(C^O) 1945, n
(BeH) 2485 cmꢀ1. HR ASAP MS (m/z):
747.1533 [M þ H]þ C36H32BN7O3PRu requires 747.1510.
4.3. Computations
All optimisations were carried out with the Gaussian 09 package
[77] using the B3LYP [78] hybrid functional and the pseudopoten-
tial LANL2DZ [79] for Ru and the 3-21G* basis set [80] for all other
atoms. These geometries were found to be true minima based on no
imaginary frequencies found. Electronic structure and TD-DFT
calculations were also carried out on the optimized geometries at
the B3LYP/LANL2DZ:3-21G* level of theory. The MO diagrams and
orbital contributions were generated with the aid of GaussView 5.0
[81] and GaussSum [82] packages, respectively.
[32] M.R. Torres, A. Vegas, A. Santos, J. Ros, J. Organomet. Chem. 309 (1986) 169.
[33] M.R. Torres, A. Santos, J. Ros, X. Solans, Organometallics 6 (1987) 1091.
[34] M.R. Torres, A. Vegas, A. Santos, J. Ros, Organometallics 7 (1988) 1233.
[35] M.R. Torres, A. Vegas, A. Santos, J. Ros, J. Organomet. Chem. 326 (1987) 413.
[36] S.K. Seetharaman, M.-C. Chung, U. Englich, K. Ruhlandt-Senge, M.B. Sponsler,
Inorg. Chem. 46 (2007) 561.
[37] A.F. Hill, R.P. Melling, J. Organomet. Chem. 396 (1990) C22.
[38] S. Bohle, G.R. Clarke, C.E.F. Rickard, W.R. Roper, W.E.B. Shepard, L.J. Wright,
J. Chem. Soc. Chem. Commun. (1987) 563.
[39] A. Gieren, C. Ruizperez, T. Hubner, M. Herberhold, A.F. Hill, J. Chem. Soc.
Dalton Trans. (1988) 1693.
[40] W.R. Roper, G.E. Taylor, J.M. Waters, L.J. Wright, J. Organomet. Chem. 157
(1978) C27.
Acknowledgements
Financial support from the EPSRC is gratefully acknowledged.
PJL held a Research School of Chemistry Visiting Fellowship whilst
on leave at the Australian National University, and holds an EPSRC
Leadership Fellowship. JDF held a Durham University Doctoral
Fellowship. WYM holds a studentship from the Durham Doctoral
Training Account.
[41] W.R. Roper, G.E. Taylor, J.M. Waters, L.J. Wright, J. Organomet. Chem. 182
(1979) C46.
Appendix A. Supplementary material
[42] M. Herberhold, A.F. Hill, J. Organomet. Chem. 395 (1990) 315.
[43] N.W. Alcock, A.F. Hill, R.P. Melling, Organometallics 10 (1991) 3898.
[44] J.D.E.T. Wilton-Ely, S.J. Honarkhah, M. Wang, D.A. Tocher, A.M.Z. Slawin,
Dalton Trans. (2005) 1930.
[45] P. Muecke, M. Zabel, R. Edge, D. Collison, S. Clement, S. Zalis, R.F. Winter,
J. Organomet. Chem. 696 (2011) 3186.
Tables of energy (eV) and composition (%) of selected frontier
orbitals. Crystallographic data for compounds 3a, 4b, 4c, 4d, 4e and
4f are deposited as CCDC 892268e892273. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
[46] X. Wu, T. Weng, S. Jin, J. Liang, R. Guo, G.-a. Yu, S.H. Liu, J. Organomet. Chem.
694 (2009) 1877.
[47] S.H. Liu, Q.Y. Hu, P. Xue, T.B. Wen, I.D. Williams, G. Jia, Organometallics 24
(2005) 769.
[48] Y. Lin, J. Yuan, M. Hu, J. Cheng, J. Yin, S. Jin, S.H. Liu, Organometallics 28 (2009)
6402.
[49] S.-H. Liu, H. Xia, K.L. Lok, R.C.Y. Yeung, Q.Y. Hu, G. Jia, J. Organomet. Chem. 683
(2003) 331.
[50] J. Gimeno, V. Cadierno, in: R.H. Crabtree, D.M.P. Mingos (Eds.), Comprehensive
Organometallic Chemistry III, Elsevier, Oxford, 2006, pp. 551e646 (Chapter
6.15).
[51] M.A.J. Tenorio, M.J. Tenorio, M.C. Puerta, P. Valerga, Organometallics 16 (2007)
5528.
[52] M.J. Tenorio, M.A.J. Tenorio, M.C. Puerta, P. Valerga, Inorg. Chim. Acta 259
(1997) 77.
[53] A.M. McNair, D.C. Boyd, K.R. Mann, Organometallics 5 (1986) 303.
[54] C.N. McEwen, R.G. McKay, B.S. Larsen, Anal. Chem. 77 (2005) 7826.
[55] M.R. Torres, A. Santos, A. Perales, J. Ros, J. Organomet. Chem. 353 (1988) 221.
[56] H.P. Xia, T.B. Wen, Q.Y. Hu, X. Wang, X.G. Chen, L.Y. Shek, I.D. Williams,
K.S. Wong, G.K.L. Wong, G.C. Jia, Organometallics 24 (2005) 562.
[57] S.H. Choi, I. Bytheway, Z.Y. Lin, G.C. Jia, Organometallics 17 (1998) 3974.
[58] K.B. Wiberg, E. Martin, J. Am. Chem. Soc. 107 (1985) 5035.
[59] A.E. Dorigo, D.W. Pratt, K.N. Houk, J. Am. Chem. Soc. 109 (1987) 6591.
Appendix B. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2012.09.001.
References
[1] W. Kaim, Inorg. Chem. 50 (2011) 9752.
[2] C.R. Jorgensen, Coord. Chem. Rev. 1 (1966) 164.
[3] C.C. Scarborough, K. Wieghardt, Inorg. Chem. 50 (2011) 9773.
[4] M.D. Ward, J.A. McCleverty, J. Chem. Soc. Dalton Trans. (2002) 275.
[5] F. Pevny, R.F. Winter, B. Sarkar, S. Zalis, Dalton Trans. 39 (2010) 8000.
[6] S. Zalis, R.F. Winter, W. Kaim, Coord. Chem. Rev. 254 (2010) 1383.
[7] W.I. Dzik, J.I. van der Vlugt, J.N.H. Reek, B. de Bruin, Angew. Chem. Int. Ed. 50
(2011) 3356.
[8] A.L. Smith, K.I. Hardcastle, J.D. Soper, J. Am. Chem. Soc. 132 (2010) 14358.
[9] P.J. Chirik, K. Wiegardt, Science 327 (2010) 794.
[10] F.A. Cotton, G. Wilkinson, Advanced Inorganic Chemistry, fourth ed., John
Wiley and Sons Inc., New York, 1980, p. 768.
S.J. Trofimenko, Prog. Inorg. Chem. 34 (1986) 115.
[60]
[61] S.P. Best, S.J. Borg, K.A. Vincent, in: W. Kaim, A. Klein (Eds.), Spectroelec-
trochemistry, Royal Society of Chemistry, Cambridge, 2008.
[62] J. Maurer, R.F. Winter, B. Sarkar, J. Fieldler, S. Zalis, Chem. Commun. (2004)
1900.
[11] C.C. Scarborough, S. Sproules, T. Weyhermueller, S. DeBeer, K. Wieghardt,
Inorg. Chem. 50 (2011) 12446.
[12] B. Albinsson, M.P. Eng, K. Pettersson, M.U. Winters, Phys. Chem. Chem. Phys. 9
(2007) 5847.
[63] (a) A.P. Scott, L. Radom, J. Phys. Chem. 100 (1996) 16502;
(b) J.C. Roder, F. Meyer, I. Hyla-Kryspin, R.F. Winter, E. Kaifer, Chem. Eur. J. 9
(2003) 2636.
[13] M.I. Bruce, A. Burgun, F. Gendron, G. Grelaud, J.-F. Halet, B.W. Skelton,
Organometallics 30 (2011) 2861.
[14] F. Paul, B.G. Ellis, M.I. Bruce, L. Toupet, T. Roisnel, K. Costuas, J.-F. Halet,
C. Lapinte, Organometallics 25 (2006) 649.
[64] A. Vleck, S. Zalis, Coord. Chem. Rev. 251 (2007) 258.

J.D. Farmer et al. / Journal of Organometallic Chemistry 721-722 (2012) 173e185
185
[65] A.V. Arbuznikov, M. Kaupp, J. Chem. Phys. 136 (2012) 014111.
[66] J. Plotner, D.J. Tozer, A. Dreuw, J. Chem. Theory Comput. 6 (2010) 2315.
[67] R.L. Cordiner, D. Albesa-Jové, R.L. Roberts, J.D. Farmer, H. Puschmann, D. Corcoran,
A.E. Goeta, J.A.K. Howard, P.J. Low, J. Organomet. Chem. 690 (2005) 4908.
[68] (a) P.J. Low, M.A.J. Paterson, A.E. Goeta, D.S. Yufit, J.A.K. Howard,
J.C. Cherryman, D.R. Tackley, B. Brown, J. Mater. Chem. 14 (2004) 2516;
(b) P.J. Low, M.A.J. Paterson, D.S. Yufit, J.A.K. Howard, J.C. Cherryman,
D.R. Tackley, R. Brook, B. Brown, J. Mater. Chem. 15 (2005) 2304.
[69] P.J. Low, M.A.J. Paterson, H. Puschmann, A.R. Goeta, J.A.K. Howard, C. Lambert,
J.C. Cherryman, D.R. Tackley, S. Leeming, B. Brown, Chem. Eur. J. 10 (2004) 83.
[70] N. Ahmad, J.J. Levison, S.D. Robinson, M.F. Uttley, Inorg. Synth. 15 (1974) 45.
[71] O. Lavastre, L. Olivier, P. Dixneuf, Tetrahedron 15 (1996) 5495.
[72] W.Y. Man, K.B. Vincent, H.J. Spencer, D.S. Yufit, J.A.K. Howard, P.J. Low,
J. Cluster Sci. (2012). http://dx.doi.org/10.1007/s10876-012-0482-y.
[73] N.G. Connelly, W.E. Geiger, Chem. Rev. 96 (1996) 877.
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven,
J.A. Montgomery Jr., J.E. Peralta, F. Ogliaro, M. Bearpark, J.J. Heyd, E. Brothers,
K.N. Kudin, V.N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari,
A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M. Millam,
M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts,
R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski,
R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth, P. Salvador,
J.J. Dannenberg, S. Dapprich, A.D. Daniels, O. Farkas, J.B. Foresman, J.V. Ortiz,
J. Cioslowski, D.J. Fox, Gaussian 09, Revision A.02, Gaussian, Inc., Wallingford
CT, 2009.
[78] (a) A.D. Becke, J. Chem. Phys. 98 (1993) 5648;
(b) C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785.
[79] (a) T.H. Dunning Jr., P.J. Hay, in: H.F. SchaeferIII (Ed.), Modern Theoretical
Chemistry, vol. 3, Plenum, New York (, 1976, pp. 1e28;
(b) P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 270;
[74] M. Krejcik, M. Danek, F. Hartl, J. Electroanal. Chem. 317 (1991) 179.
[75] G.M. Sheldrick, Acta Cryst. A 64 (2008) 112.
(c) W.R. Wadt, P.J. Hay, J. Chem. Phys. 82 (1985) 284;
(d) P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 299.
[76] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, J. Appl.
Cryst. 42 (2009) 339.
[77] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb,
J.R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson,
H. Nakatsuji, M. Caricato, X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino,
G. Zheng, J.L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
[80] (a) G.A. Petersson, M.A. Al-Laham, J. Chem. Phys. 94 (1991) 6081;
(b) G.A. Petersson, A. Bennett, T.G. Tensfeldt, M.A. Al-Laham, W.A. Shirley,
J. Mantzaris, J. Chem. Phys. 89 (1988) 2193.
[81] R.D. Dennington II, T.A. Kieth, J.M. Millam, Gaussian Inc, Wallingford, CT,
2008.
[82] N.M. O’Boyle, A.L. Tenderholt, K.M. Langner, J. Comput. Chem. 29 (2008) 839.