Comparison of (triphenylphosphine)ruthenium complexes containing the 2,2′:6′,2″-terpyridine (trpy) and 4,4′,4″-tri-t- butyl-2,2′:6′,2″-terpyridine (trpy*) ligands

Article abstract of DOI:10.1016/S0020-1693(03)00300-1

A comparison of (triphenylphosphine)ruthenium(II) complexes containing the 2,2′:6′,2″-terpyridine (trpy) and 4,4′,4″-tri-t- butyl-2,2′:6′,2″-terpyridine (trpy*) ligands was conducted. Electronic spectra and electrochemical data readily differentiated the trans- and cis-[RuCl₂(trpy or trpy*)(PPh₃)] complexes. ¹H, ¹³C and ³¹P NMR assignments were made for each of the isomers as well as the trans-[RuCl(trpy*) (PPh₃)₂](PF₆) complex. Notably, the ³¹P chemical shift differences between the trans- and cis-[RuCl ₂(trpy*)(PPh₃)] complexes were not dramatic and the ¹H NMR spectra were found to be the best way for determining the position of the triphenylphosphine ligand relative to the terpyridyl ligand. X-ray crystal structure analyses confirmed the structures of the cis-[RuCl ₂(trpy*)(PPh₃)] and trans-[RuCl(trpy*) (PPh₃)₂]PF₆ complexes. Similar π-stacking interactions occurred between the phenyl rings and the trpy* ligand in both complexes.

Full text of DOI:10.1016/S0020-1693(03)00300-1

Inorganica Chimica Acta 355 (2003) 103ꢀ115
/
www.elsevier.com/locate/ica
Comparison of (triphenylphosphine)ruthenium complexes containing
the 2,2?:6?,2??-terpyridine (trpy) and 4,4?,4??-tri-t-butyl-2,2?:6?,2??-
terpyridine (trpy*) ligands
Susan B. Billings a, Michael T. Mock a, Kevin Wiacek a, Melinda B. Turner a,
W. Scott Kassel a, Kenneth J. Takeuchi b, Arnold L. Rheingold c, Walter J. Boyko a,*,
Carol A. Bessel a,*
a Department of Chemistry, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085, USA
b Department of Chemistry, State University of New York at Buffalo, Buffalo, NY 14214, USA
c Department of Chemistry and Biochemistry, University of Delaware, Delaware, DE 19716, USA
Received 22 January 2003; accepted 3 May 2003
Abstract
A comparison of (triphenylphosphine)ruthenium(II) complexes containing the 2,2?:6?,2??-terpyridine (trpy) and 4,4?,4??-tri-t-butyl-
2,2?:6?,2??-terpyridine (trpy*) ligands was conducted. Electronic spectra and electrochemical data readily differentiated the trans- and
1
cis-[RuCl2(trpy or trpy*)(PPh3)] complexes. H, 13C and 31P NMR assignments were made for each of the isomers as well as the
trans-[RuCl(trpy*)(PPh3)2](PF6) complex. Notably, the 31P chemical shift differences between the trans- and cis-[RuCl2(tr-
py*)(PPh3)] complexes were not dramatic and the 1H NMR spectra were found to be the best way for determining the position of the
triphenylphosphine ligand relative to the terpyridyl ligand. X-ray crystal structure analyses confirmed the structures of the cis-
[RuCl2(trpy*)(PPh3)] and trans-[RuCl(trpy*)(PPh3)2]PF6 complexes. Similar p-stacking interactions occurred between the phenyl
rings and the trpy* ligand in both complexes.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Ruthenium; NMR spectroscopy; Crystal structures; Terpyridine complexes
1. Introduction
contrasted with 2,2?-bipyridine (bpy)-containing ruthe-
nium complexes [7ꢀ11].
/
The 2,2?:6?,2??-terpyridine (trpy) ligand has been
widely studied as a chelating agent due to its chemical
stability [1]. Several families of complexes containing
substituted-trpy ligands have demonstrated unusual
While new synthetic procedures have considerably
reduced the high cost associated with the synthesis of the
trpy ligand [12], a number of synthetically modified trpy
analogues have been developed to improve the ligand
yield, the ligand chelating ability, and the specific
electrochemical and/or spectroscopic properties of the
transition metal complexes which incorporated these
redox properties [2ꢀ4] and subsequently some of the
/
families have been studied as stoichiometric and/or
catalytic oxidants [5] as well as molecular recognition
agents [6]. Additionally, the photochemistry and photo-
physics of some complexes containing substituted-trpy
ligands remain a current interest, especially when
ligands [2ꢀ
/
11,13ꢀ17]. The 4,4?,4??-tri-alkyl-2,2?:6?,2??-
/
terpyridine ligands remain some of the most easily
synthesized and purified of the substituted-trpy analo-
gues [18].
Ben Hadda and Le Bozec [19,20] have reported the
coordination of 4,4?,4??-tri-t-butyl-2,2?:6?,2??-terpyridine
(trpy*) and 4,4?-di-t-butyl-2,2?-bipyridine (bpy*) in
complexes of the form [Ru(bpy or bpy*)(trpy*)X]nꢁ
* Corresponding authors. Tel.: ꢁ
/
1-610-519 4867 (W.J. Boyko), ꢁ1-
/
610-519 4876 (C.A. Bessel); fax: ꢁ1-610-519 7167.
/
E-mail addresses: walter.boyko@villanova.edu (W.J. Boyko),
carol.bessel@villanova.edu (C.A. Bessel).
(where Xꢂ
/
Clꢃ or CF3SO3ꢃ and nꢂ
/
1 or XꢂH2O and
/
0020-1693/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00300-1

104
S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ115
/
nꢂ
/
2) or Ru(bpy*)2Cl2. Le Bozec and coworkers [21]
all measurements were conducted at room temperature
using 0.1 M tetrabutylammonium tetrafluoroborate
(TBAB) in CH2Cl2 or CH3CN as the electrolyte solu-
have also reported the results of thermal and photo-
chemical isomerization studies which converted trans-
[RuCl2(trpy*)(Y)] to cis-[RuCl2(trpy*)(Y)] (where Yꢂ
/
tion. The E1/2 values for ferrocene at ꢁ
CH3CN or ꢁ0.50 V in CH2Cl2 were used as an internal
standard.
1H, 13C and 31P NMR spectra were recorded with a
Varian 300 MHz Fourier Transform spectrometer in
deuterated methylene chloride (CD2Cl2). 1H NMR
spectra were obtained at 299.9 MHz and referenced to
tetramethylsilane. 13C NMR spectra were obtained at
/
0.40 V in
CO, PPh3, PMe3, PMePh, P(OPh)3 or P(OMe)3). In the
latter publication, the authors used cyclic voltammetry
to monitor the relative amounts of both the trans- and
cis-[RuCl2(trpy*)(Y)] products. The introduction of the
bulky t-butyl substituent on the trpy ligand was
observed to increase the solubilities of the (trpy*)ruthe-
nium complexes in non-polar solvents relative to the
parent (trpy)ruthenium complexes. The t-butyl substi-
tuents were also observed to donate electron density to
the metal center and reduce the redox potentials of the
resultant trpy* complexes relative to their trpy analo-
gues.
/
75.4 MHz and referenced to CD2Cl2. Protonꢀ
/proton
COSY and carbonꢀhydrogen HETCOR were run with
/
standard Varian-supplied pulse sequences to confirm
assignments. NMR spectral assignments for quaternary
carbons were confirmed using the ChemWindow3 C-13
NMR module computer application [25].
Our group is interested in sterically large ligands and
their effect on the properties of transition metal com-
The single-crystal X-ray diffraction experiments were
performed on a Siemens P4/CCD diffractometer. Sys-
tematic absences uniquely defined the space group for
both crystal structures and the choice of the space
groups resulted in chemically reasonable structures that
remained stable over the course of structural refine-
ments. The structures were solved using direct methods
and subsequent difference Fourier syntheses. Final
structure refinements were made using full-matrix,
least-squares procedures. All non-hydrogen atoms
were refined with anisotropic displacement parameters.
All hydrogen atoms were calculated in idealized posi-
tions. All software used in the structure determination
and sources of the scattering factors were contained in
the SHELXTL (5.10) program library [26].
plexes [22ꢀ24]. We report here a more detailed compar-
/
ison of the trans- and cis-[RuCl2(trpy*)(PPh3)]
complexes with their trpy analogues using electronic
spectroscopy, electrochemistry and 1H, 13C and 31P
NMR spectroscopies. The electronic and 13C NMR
spectroscopies of the [RuCl2(trpy*)(PPh3)] isomers have
not been previously reported. We have also noted
1
significant changes in the H and 31P NMR spectra for
the trans-[RuCl2(trpy*)(PPh3)] isomer on aging; these
changes have not been previously reported. Addition-
ally, we report the X-ray structural analysis of the cis-
[RuCl2(trpy*)(PPh3)] complex. To the best of our
knowledge, this is the first time a crystal structure of
the cis-geometry has been reported for (chloro)(pho-
sphine)ruthenium complexes. Finally, we report the
crystal structure of trans-[RuCl(trpy*)(PPh3)2](PF6)
and its comparison with similar trans-di(phosphine)(tr-
py)ruthenium complexes.
2.2. Materials and preparations
Reagents were obtained from Aldrich Chemical Co.
and used as received. The trpy* ligand was prepared
according to slight variations in the literature proce-
dures described by Rosevear and Sasse [18] and Ben
Hadda and Le Bozec [19]. Preparations of RuCl3(trpy*)
(1), trans-[RuCl2(trpy*)(PPh3)] (2) and cis-[RuCl2(tr-
py*)(PPh3)] (3) have been previously reported [21]. The
following are variations of literature procedures. All
syntheses were carried out under N2(g), unless otherwise
noted.
2. Experimental
2.1. Physical measurements
Elemental analyses were conducted by Atlantic Mi-
crolabs, Norcross, GA. Electronic spectra were mea-
sured with
a
Cary 1G Diode Array UVꢀVis
/
spectrophotometer. Cyclic voltammetry was conducted
with a Bioanalytical Systems (BAS) 50 W potentiostat.
Electrochemical measurements were conducted using a
standard three-electrode cell arrangement. A saturated
sodium chloride calomel (SSCE) reference electrode, a
platinum wire auxiliary electrode and a platinum work-
ing electrode (Bioanalytical Systems) were used. The
working electrode was polished with 0.5 mm alumina
(Buehler Ltd. or Bioanalytical Systems) for 30 s, then
sonicated in distilled water and rinsed with methanol
rinse just prior to use. No IR corrections were made and
2.2.1. trans-[RuCl2(trpy*)(PPh3)] (2)
A 1.01 g (1.66 mmol) of 1 and 0.650 g (2.48 mmol)
triphenylphosphine (PPh3) were mixed in 300 ml CH2Cl2
and outgassed with N2(g). Triethylamine (15 ml) was
added and the solution was heated to reflux for 1.5 h
during which time the solution became purple. The
solvent was removed using a rotary evaporator and the
product was redissolved in a minimal amount of CH2Cl2
before passing down an alumina column. The column
was eluted with CH2Cl2. The initial purple band was

S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ
/115
105
collected, reduced in volume and then dripped into
stirring hexanes. The purple solid was collected by
vacuum filtration, washed with a minimal amount of
hexanes, and air-dried. Often the product contained a
small amount of impurity and so column chromatogra-
phy was repeated a second time. Yield: 0.711 g (0.85
mmol), 51%. Anal. Calc. for RuC45H50Cl2PN3: C,
64.64; H, 6.04. Found: C, 64.52; H, 6.12%.
produces 3. The combination of 3 with excess PPh3
produces the cationic species 4 which is precipitated
after metathesis with PF6ꢃ. Complex 4 has not pre-
viously been reported.
3.2. Electronic spectroscopy
The electronic spectra of the ruthenium complexes 2ꢀ
/
4 as well as their trpy analogues are reported in Table 1.
Electronic spectra have not previously been reported for
the (trpy*)ruthenium complexes. The absorbances in the
2.2.2. cis-[RuCl2(trpy*)(PPh3)] (3)
A 0.0560 g sample (0.0669 mmol) of 2 was dissolved
in 50 ml CH2Cl2 and refluxed by heating under a 120-W
spotlight for 24 h. During this time, the color of the
solution changed from purple to reddish-violet. The
solid was reduced in volume and dripped into stirring
diethyl ether. The product was vacuum-filtered, washed
with a minimal amount of diethyl ether, and air-dried.
Yield: 0.0356 g (0.0428 mmol), 64%. Elemental analysis
was not performed as X-ray structural data were
available (vide infra).
UV region have been assigned to intraligand p0p*
/
transitions within both the trpy* ligand and the phenyl
groups of the triphenylphosphine ligand(s) [23,24,27,28].
In the visible region, the lower energy absorption
bands have been assigned to metal-to-ligand charge
transfer (MLCT) transitions in analogy to other ruthe-
nium(trpy) complexes [24,27,28]. The differences in the
electronic spectra of the trans- and cis-[RuCl2(L)(PPh3)]
(where Lꢂ
lowest energy absorption bands are assigned as mani-
folds of transitions which are predominantly Ru(dp)0
/
trpy or trpy*) complexes are significant. The
2.2.3. trans-[RuCl(trpy*)(PPh3)2]PF6 (4)
/
A 0.500 g (0.821 mmol) sample of 1 was mixed with
1.08 g (4.11 mmol) of triphenylphosphine along with 150
ml methylene chloride and 12.5 g of zinc amalgam. The
reaction was heated to reflux for 24 h and then
irradiated under a spotlight for 18 h. After the reaction
was completed, the mixture was filtered to remove the
zinc amalgam and the solution was reduced to dryness
using a rotary evaporator. A solution of 30 ml of
ethanol and 45 ml of water was added to dissolve the
filtrate before a solution of 3.5 g NH4PF6 dissolved in a
minimum amount of water was added, to cause the
ruthenium complex to precipitate. The crude precipitate
was collected by vacuum filtration, washed with a
minimum amount of water, and air-dried. This product
was purified on an alumina column using a CH2Cl2/
CH3OH eluent (90:10, v/v). The major orange band was
reduced in volume on a rotary evaporator, dripped into
stirring hexanes, and vacuum-filtered. The pure product
was washed with a minimal amount of hexanes and air-
dried. Yield: 0.674 g (0.558 mmol), 68%. Anal. Calc. for
RuP3ClN3C63H65F6: C, 62.66; H, 5.39. Found: C, 62.37;
H, 5.57%.
trpy*(p*) in character. In the trpy complexes, the lmax
value of the lowest energy MLCT band in the cis-
[RuCl2(L)(PPh3)] isomer (3?) is approximately 18 nm
lower in wavelength than that for the corresponding
trans-[RuCl2(L)(PPh3)] isomer (2?) [27]. In the trpy*
complexes, this shift in wavelength for the two isomers is
exactly the same, i.e., the MLCT band of 3 is 18 nm
lower in wavelength than that of complex 2. The shifts
to higher energy and the more positive Ru(III/II)
potentials of the cis-isomers are consistent with stabili-
zation of the dp levels in the cis-isomer when compared
to the trans-isomer [27].
The addition of a second triphenylphosphine ligand
to 3 and the consequent change from a neutral to a
positively charged molecule results in a shift of the
MLCT bands (again assigned to Ru(dp)0trpy*(p*)
/
transitions) to higher energies. The shift from cis-
[RuCl2(L)(PPh3)] to trans-[RuCl(L)(PPh3)2]ꢁ is evident
in a decrease of the lmax of 58 nm for the trpy complexes
and 51 nm for the trpy* complexes.
Interestingly, a comparison of the trpy*-containing
complexes 2 and 3 with the trpy-containing complexes 2?
and 3? shows that the lmax of the MLCT bands of the
trpy* complexes are 7 nm lower in wavelength than
those of the trpy complexes. These small shifts to lower
wavelength are consistent with the greater electron-
donating character of the t-butyl groups present on
trpy* and are also evident in the electrochemical data
(vide infra). The E1/2 values of the trpy* complexes (2
and 3) are 40 mV less than the corresponding trpy
complexes (2? and 3?). The slightly higher energies of the
MLCT bands observed for the trpy* complexes suggest
that p*-orbitals of the trpy* ligand increase the energy
gap and stabilize the ruthenium(II) state.
3. Results and discussion
3.1. Synthesis
Scheme 1 represents the synthesis of complexes 2ꢀ4
/
(where the tridentate, N-donor ligand on the meridional
plane is trpy*; see Scheme 2). The synthesis is initiated
by combining complex 1 with PPh3 and a reducing
agent, NEt3, to form complex 2. Irradiation of a
solution of 2 isomerizes the ruthenium geometry and

106
S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ115
/
Scheme 1.
the quasi-reversible Ru(III/II) couples are summarized
in Table 1. For the trpy* complexes, the Ru(III/II)
potential for 3 is 120 mV more positive than that for 2,
an effect that has been observed for other trans ꢀ
/
cis
pairs [21,23,24,27ꢀ29]. The addition of a second triphe-
/
nylphosphine ligand to complex 3 (to produce complex
4) increases the E1/2 values by an additional 260 mV,
consistent with other trans-(diphosphine)ruthenium
Scheme 2.
complexes [23,24,27ꢀ29].
/
Interestingly, a comparison of the electronic spectra
of 4 and 4? indicates no significant differences in the
energies of the absorbance bands, i.e., the lmax of the
MLCT band for both the trpy* and trpy complexes is
473 nm even though the E1/2 value of the trpy* complex
4 is 90 mV lower than that of the trpy complex 4?. The
inconsistency in the differences between the trpy and
trpy* absorption maxima and E1/2 values may indicate
that multiple electronic transitions are involved and, as
stated above, the visible absorbances actually reflect a
manifold of transitions with slightly different energies
due to the geometries of the particular complexes.
Hadda and Le Bozec [19,20] reported that the
presence of the tert-butyl substituents enhanced the
electron-donating influence of the trpy ligand when
[Ru(bpy)Cl(trpy)]ꢁ
[Ru(bpy*)Cl(trpy*)]ꢁ. They observed a decrease in the
potential of the Ru(III)/(II) couple of approximately 75
mV when both trpy* and bpy* were substituted for trpy
and bpy, respectively. We have observed both smaller
(40 mV for 2 vs. 2? and 3 vs. 3?) and larger (100 mV for 4
vs. 4?) changes in the Ru(III/II) redox potentials when
trpy* was substituted for trpy in ruthenium(II) com-
plexes. While it is expected that the electron-donating
ability of the trpy* ligand is constant in each of the
was
compared
to
complexes, the potentials of these complexes 2ꢀ4 may
/
3.3. Electrochemistry
also be affected by the steric size of the trpy* ligand. The
size of spectator ligands has been observed to effect the
redox potential of the metal center in several examples in
the literature [22b,30]. The importance of the steric
Cyclic voltammetry was used to measure the redox
potentials and reversibilities of the (trpy*)ruthenium
complexes in non-aqueous media. The E1/2 values for
Table 1
Electronic spectroscopy and electrochemical data for ruthenium(trpy) and (trpy*) complexes
Complex
E1/2 (V) (DEp, mV) a
lmax, nm (10ꢃ3 o, Mꢃ1 cmꢃ1
)
trans-[RuCl2(trpy)(PPh3)] (2?)
trans-[RuCl2(trpy*)(PPh3)] (2)
cis-[RuCl2(trpy)(PPh3)] (3?)
cis-[RuCl2(trpy*)(PPh3)] (3)
trans-[RuCl(trpy)(PPh3)2][PF6] (4?)
trans-[RuCl(trpy*)(PPh3)2][PF6] (4)
ꢁ
/
0.46 (70) b,c,d
705 (sh), 549 (4.66), 403 (4.71), 375 (sh), 331 (17.9), 320 (sh), 286 (sh), 275 (16.5) b,e
0.41 b,f 694 (sh), 542 (4.5), 404 (5.3), 328 (21.9), 319 (sh) b
ꢁ
/
0.42 (90) b; ꢁ
/
ꢁ
/
0.58 (65) b,c,d
531 (4.79), 488 (sh), 363 (sh), 319 (20.8), 286 (sh), 275 (16.3) b,e
ꢁ
/
0.54 (130) b; ꢁ
/
0.55 b,f 524 (5.2), 497 (sh), 356 (sh), 313 (25.0), 290 (sh), 277 (26.3) b
ꢁ
/
0.89 (70) c,d,g
0.80 (60) g
473 (3.62), 431 (sh), 330 (sh), 312 (23.2), 268 (43.2) g
ꢁ/
473 (4.7), 436 (sh), 328 (sh), 311 (30.5), 269 (48.2), 231 (sh) g
a
Unless otherwise noted, half-wave potentials (E1/2
electrode with Pt working and auxiliary electrodes. Data were recorded at 100 mV sꢃ1 in 0.1 M Bu4NBF4 and referenced vs. internal ferrocene.
ꢂ
/
Ep,anodicꢁEp,cathodic/2) were measured from cyclic voltammograms vs. an SSCE reference
/
DEpꢂ
/
jEp,c
ꢃ
/
Ep,aj.
b
c
d
e
f
Recorded in CH2Cl2.
Reported in Ref. [27].
E1/2 vs. SSCE in 0.1 M Bu4NPF6 at 200 mV sꢃ1 with a Pt working electrode.
Reported in Ref. [23].
Reported in Ref. [21]; E1/2 vs. unreported reference, in 0.1 M Bu4NPF6 at 200 mV sꢃ1 with a Pt working electrode.
Recorded in CH3CN.
g

S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ
/115
107
influence of the trpy* ligand was further corroborated
by the differences in peak potentials (DEpꢂjEp,c
the 1H NMR spectrum for the uncoordinated trpy*
ligand has been reported by Ben Hadda and Le Bozec
[19] in CD3Cl. Herein, we report the 1H NMR spectrum
of trpy* (taken in CH2Cl2 for easier comparison with
our ruthenium complex spectra) as well as the 13C NMR
spectrum of the uncoordinated trpy* ligand (which has
not previously been reported).
In analogy to trpy, the uncoordinated trpy* contains
terminal pyridine rings which are magnetically equiva-
lent. Uncoordinated trpy* is also expected to demon-
strate a trans,trans-configuration in solution due to the
repulsion of the non-bonding electrons on the nitrogen
/
ꢃ
/
Ep,aj). For the trpy* complexes, the DEp values of 60ꢀ
/
130 mV were, in general, more variable and considerably
larger than those of the analogous trpy complexes
(DEpꢂ
/
65ꢀ70 mV). This increase in DEp is indicative
/
of greater electrochemical irreversibility in the trpy*
complexes. Such irreversibility may be due to the
difficulty of the trpy* complexes to compensate (in
terms of changing bond lengths and angles), when the
complexes are oxidized and/or reduced. This difficulty
may be due to the steric strain induced by the interaction
of the t-butyl groups of the trpy* ligand and the phenyl
rings of the PPh3 ligand(s). This is further discussed
during the examination of the X-ray crystal structures of
3 and 4.
atoms. The protonꢀproton coupling constants (e.g., Jab,
/
Jac and Jbd) were used to confirm the proton assign-
ments in many of the reported ruthenium complexes.
The protonated carbons of the 13C NMR spectrum were
assigned from HETCOR analysis. Carbons c and d are
of the correct height and in the proper region of the
spectrum as predicted by the ChemWindow 3 C-13
NMR Module [25]. Carbons e and f are in the correct
region; however, their individual shifts may be switched
since their values are close and both carbons have the
same intensity (as expected).
3.4. NMR spectroscopy
1H, 13C and 31P NMR spectroscopies were used to
confirm the structures and investigate the effects of
changes in geometry of the low spin, d6, (trpy*)ruthe-
nium(II) complexes. Scheme 2 gives the designations
used in the discussion of the NMR assignments; Table 2
contains 1H NMR assignments (chemical shifts and
coupling constants) and Table 3 contains 13C and 31P
NMR assignments.
3.4.2. Analyses of triphenylphosphine spectra
1
The H NMR spectrum of free triphenylphosphine
(PPh3) shows one broad singlet in the aromatic region at
d 7.28 ppm in CDCl3 [31]. The 13C NMR spectrum of
PPh3 shows seven peaks at d 137.27, 137.12, 133.79,
133.53, 128.60, 128.44, and 128.35 ppm in CDCl3 [31].
NMR studies have been successful in characterizing the
3.4.1. Analyses of the free trpy* spectra
We have previously discussed revised NMR spectral
assignments for the uncoordinated trpy ligand [23] and
Table 2
1H NMR chemical shifts for the uncoordinated trpy* ligand and the ruthenium(trpy*) and trpy complexes
1H chemical shifts
trpy*
trpy
Ligand
Fresh 2
Aged 2
3
4
2?
3?
4? a
A
8.586
7.353
8.019
6.856
8.110
6.861
9.106
7.333
8.808
7.080
8.286
6.926
7.662
8.066
8.153
7.901
7.836
7.320
7.375
9.270
7.338
7.666
7.746
7.561
7.402
7.227
7.055
7.179
9.009
7.107
7.687
7.745
7.469
7.469
7.135
7.075
7.243
B
C
ꢀ/
8.756
8.481
ꢀ/
7.976
8.057
ꢀ/
7.992
8.108
ꢀ/
7.707
7.627
ꢀ/
7.505
7.415
D
G
H
ꢀ/
ꢀ/
ꢀ/
ꢀ/
1.426
1.454
5.3
ꢀ/
ꢀ/
ꢀ/
ꢀ/
J
7.775
7.250
7.304
1.293
1.506
6.0
7.787
7.255
7.305
1.296
1.514
6.1
7.198
7.052
7.182
1.375
1.470
6.0
7.056
7.038
7.229
1.302
1.480
6.0
K
L
Tb2
Tb4
Jab
Jac
Jad
Jbc
Jbd
Jcd
Jgh
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
5.4
1.3
Nd
7.4
1.6
5.8
1.7
0.7
7.6
1.4
8.1
8.0
5.4
1.5
0.6
7.4
1.5
8.1
8.0
ꢀ/
0.7
ꢀ
/
ꢀ/
nd
ꢀ/
0.5
ꢀ/
nd
ndb
ꢀ/
2.1
ꢀ/
2.2
ꢀ/
2.2
ꢀ/
2.1
ꢀ/
1.8
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
8.3
c
a
NMR spectrum has been previously reported in Ref. [23].
nd, not determined.
Protons g and h are magnetically equivalent; the coupling constant cannot be determined.
b
c

108
S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ115
/
Table 3
13C and 31P NMR chemical shifts for the uncoordinated trpy* ligand and the ruthenium(trpy*) and trpy complexes
trpy*
trpy
13C chemical shifts
ligand
fresh 2
aged 2
3
4
2?
3?
4? a
a
149.10
121.15
160.85
118.45
156.46
155.51
117.92
162.18
158.02
122.55
157.93
119.64
160.75
160.63
118.26
159.59
nd
158.04
122.82
nd b
154.36
124.00
160.09
118.55
159.00
155.43
118.39
159.68
133.08
133.22
127.93
129.11
35.32
30.65
35.65
31.09
42.0
155.14
157.86
124.93
135.40
122.27
nd
154.36
126.26
135.09
121.26
159.47
158.58
120.77
129.82
131.69
132.62
127.67
128.91
155.79
126.84
136.87
122.66
158.18
157.66
122.83
132.52
130.13
133.23
128.57
130.10
b
124.31
161.81
119.04
157.68
157.25
119.44
157.77
130.82
133.30
128.37
129.87
35.39
30.50
35.83
31.21
39.2
c
d
119.88
e
nd
nd
f
nd
g
118.17
120.48
131.05
nd
h
nd
i
ꢀ/
ꢀ/
ꢀ/
ꢀ/
35.28
30.66
35.59
30.87
135.91
135.56
127.91
129.41
35.12
30.61
35.94
30.98
32 c
j
135.57
127.99
129.43
35.09
30.70
35.97
31.00
nd
135.09
127.64
129.17
k
l
tb1
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
41.9
9.4
ꢀ/
tb2
tb3
ꢀ/
ꢀ/
39.2
10.3
9.1
tb4
1JPC
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
nd
2JPC
nd
nd
10.1
8.5
9.5
9.2
10.3
9.0
8.2
6.5
0
3JPC
9.2
2.3
4JPC
nd
ꢀ/0
2.2
44.20
ꢀ
/
0
22.66
ꢀ
/
1.6
21.10
31P chemical shifts
ꢀ/
ꢀ/45
46.04
44.20 d
41.1
a
i
i
For 4 and 4?, the j JPCj coupling is actually j JPCꢁj
/
JPCj where jꢂiꢁ
/
/
2.
b
c
nd, not determined.
Unreliable values were obtained due to line broadening.
Aged sample had a 31P NMR chemical shift of 44.20 ppm with a JPC
d
ꢂ37 Hz.
/
dynamic processes of PPh3 ligands in many transition
metal complexes [32,33]. Rotation about the three Pꢀ
Cipso bonds as well as the metalꢀP bond is possible.
Brock and Ibers [34] have estimated these barriers to
rotation to be less than 2 kcal molꢃ1. For steric reasons,
the three phenyl groups generally adopt a chiral
propeller-like conformation (with either a clockwise or
counter-clockwise screw configuration) and this is ob-
served in the crystal structures of 3 and 4 (vide infra)
[33]. The interconversion of the two enantiometric
which increased by 0.091 and 0.051 ppm on aging,
respectively. The chemical shifts due to the aging of 2
are much larger for the trpy* pyridyl rings than for the
PPh3 groups (maximum chemical shift difference on
aging was 0.012 ppm) or the t-butyl groups of the trpy*
ligand (maximum difference on aging was 0.008 ppm).
At this point, we cannot explain the cause of the shifts
caused by the aging of 2. It should be noted, however,
that the chemical reactivity of 2 did not change with
aging (i.e., both fresh and aged samples of 2 converted
to 3 with similar yields and purities) and the chemical
shift differences between the fresh and aged samples of 2
are significantly smaller than the chemical shift differ-
ences found between the isomers (e.g., 2 vs. 3 or 4).
Additionally, chemical shift differences were not ob-
served with fresh and aged samples of 3 or 4, nor where
/
/
configurations or full rotation about any Pꢀ
/
Cipso bond
requires cooperative motion within the PPh3 [34].
3.4.3. Analyses of the ruthenium complex spectra
The literature contains very little NMR spectral data
on the differences between trans- and cis-[RuCl2(trpy or
trpy*)(PR3)] complexes, even though these complexes
are diamagnetic, monomeric, and highly soluble in a
variety of common NMR solvents [21,26]. We herein
report the NMR comparison of the trpy* and analogous
they observed for any of the trpy analogues (2?ꢀ4?). The
/
13C NMR shifts did show some changes between aged
and fresh samples of 2; however, these differences in
chemical shift are not as significant as those found in the
1H NMR spectra. The largest differences in 2 on aging
occur with Cb and Cd which shift downfield by 0.27 and
0.24 ppm, respectively. Notably, while others have
reported the 1H NMR spectrum of 2 and 3, no mention
was made of the instability in the NMR spectrum of 2
with time. For the rest of our discussion, we will make
comparisons based on fresh samples of 2 only.
trpy (2?ꢀ4?) ruthenium complexes.
/
1
Interestingly, there are subtle changes in H NMR
shifts of the trpy* protons of 2 when fresh (observed
immediately after purification) and aged (left in CD2Cl2,
in the dark, for 1ꢀ2 days) samples are compared in
/
CD2Cl2 (see Table 2). These differences can be signifi-
cant as demonstrated by chemical shifts of Ha and Hg

S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ
/115
109
ligand, the chemical shifts in 2 and 2? show downfield
shifts in the PPh3 resonances when the chemical shifts in
the complexes are compared to those of free PPh3. For
complexes 3 and 4, the PPh3 resonances are 0.05ꢀ0.24
/
ppm upfield of their expected position and for the
analogous trpy compounds these shifts were observed
0.04ꢀ0.21 ppm upfield. These shifts have been attrib-
/
uted to a mutual anisotropic deshielding between the
phenyl rings of the PPh3 ligand and the trpy ligand [23].
As only three chemical shifts are observed for the PPh3
ligand(s) of 2ꢀ
bonds as well as those of the Ruꢀ
/
4, free rotations about all three Pꢀ
/
Cipso
/
P bonds are indicated.
Notably, the ORTEP diagrams of 3 and 4 (Figs. 2 and 3,
respectively) show that (a) each phenyl group of the
PPh3 ligands has a slightly different orientation depend-
ing on its position relative to the trpy* ligand and (b) the
PPh3 ligands in 3 and 4 are similarly arranged regardless
of whether there is one or two PPh3 ligands in the
complex. In each structure, two of the phenyl rings of
each PPh3 ligand are located in an approximately
parallel arrangement to the trpy* ligand and the third
phenyl ring is nearly perpendicular to the plane of the
terminal trpy* pyridines. From the NMR data and the
X-ray structures of 3 and 4, it is postulated that as the
PPh3 ligand(s) rotates along the Ruꢀ
phenyl ring adjusts its orientation along the Pꢀ
axis. That is, as each phenyl ring moves around the Ruꢀ
/
P bond, each
/Cipso
Fig. 1. Proton NMR spectra (400 MHz, CD2Cl2) of (a) a fresh sample
of trans-[RuCl2(trpy*)(PPh3)] (2) and (b) cis-[RuCl2(trpy*)(PPh3)].
The proton assignments are the same as that of Scheme 2.
/
P bond, it may travel in a monotonic or slightly
oscillatory path over the trpy* ring, but as it clears the
1
Fig. 1 compares the aromatic region of the H NMR
spectrum of a freshly prepared sample of 2 with the
same region of 3. The proton shifts in these ruthenium
complexes clearly reflect the position of the triphenyl-
phosphine ligand(s) relative to the meridional trpy or
trpy* ligands. For example, the shift for the Ha protons
in 2 (or 2?) are 1.09 (0.98) ppm upfield of those in 3 (3?)
and 0.79 (0.72) ppm upfield of that in 4 (4?). Other
protons show similar, though slightly less dramatic,
trends: the Hb of trpy* (trpy) demonstrates a downfield
shift of 0.48 (0.41) ppm on going from 2 (2?) to 3 (3?) and
0.22 (0.18) ppm on going from 2 (2?) to 4 (4?). In
1
addition to changes in the H spectra of the trpy* and
trpy ligands on change in geometry, the triphenylpho-
sphine ligand(s) also shows significant changes in their
chemical shifts when the geometry about the ruthenium
center is altered. The Hj of trpy* (trpy) demonstrates a
upfield shift of 0.58 (0.61) ppm on going from 2 (2?) to 3
(3?) and 0.72 (0.70) ppm on going from 2 (2?) to 4 (4?).
These differences clearly delineate the position of the
triphenylphosphine ligand as being either in the same
plane as the terpyridyl ligand (lower Ha, higher Hb and
Hj chemical shifts) or perpendicular to the terpyridyl
ligand (higher Ha and Hb and lower Hj chemical shifts).
When the proton chemical shifts of the triphenylpho-
sphine ligand are compared to the uncoordinated PPh3
Fig. 2. ORTEP diagram of cis-[RuCl2(trpy*)(PPh3)] (3) viewed down
the P(1)ꢀ
/
RuꢀCl(2) axis (drawn at 10% probability).
/

110
S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ115
/
Fig. 3. ORTEP diagram of trans-[RuCl(trpy*)(PPh3)2]ꢁ cation (4) viewed down the P(2)ꢀ
/
RuꢀP(1) axis (drawn at 10% probability).
/
plane above (and/or below) the trpy* ligand, the phenyl
rings may rotate about the PꢀCipso bonds to become
cogging mechanisms of the phenyl rings when under-
going concerted or unconcerted motions. While the
proton shifts are very sensitive to the relative orientation
of the trpy* ligand and the phenyl rings of the
phosphine(s), the protons do screen the carbons nuclei.
The chemical shifts in 13C NMR spectra are less
sensitive to the changing geometries about ruthenium
center (see Table 3). A comparison of the carbon
chemical shifts shows that the Ca of both the trpy and
trpy* complexes has greater shielding (occurs at higher
frequency) when the triphenylphosphine is moved from
the meridional position in the 2 or 2? isomer to the axial
position in the other 3 (3?) or 4 (4?).
/
perpendicular to the trpy* ring. This rotation causes
time averaging of the ortho and meta proton resonances
and results in only three unique proton resonances for
the PPh3-phenyl rings. Notably, the bulky t-butyl
groups of the trpy* ligand do not sterically hinder of
the motion of the PPh3 ligand(s) in either 3 or 4. Finally,
while we have not been able to grow X-ray quality
crystals of 2, the NMR spectrum of this complexes
indicates that even the positioning of the PPh3 ligand in
the same plane as the trpy* ligand does not hinder the
rotation of the Ruꢀ
/
P or Pꢀ
/
Cipso groups.
If the rotations of the Ruꢀ
/
P and PꢀCipso bond freely
/
The triphenylphosphine ligands in the 13C NMR
spectrum of 4 are observed as a set of four triplets.
The signals are triplets due to virtual coupling to the
occur, the chemical shifts of the PPh3 ligands are
expected to be upfield relative to the free PPh3 ligand,
since the PPh3 ligands of 3 and 4 spend more time in the
shielding areas over the trpy* compared to the two
pockets between the chlorine and each of the terminal
pyridines of trpy* ligand. Similarly, the trpy* protons
(except Ha) should experience shielding by the phenyl
rings of the PPh3 ligands and should be found upfield
when compared to the free trpy* ligand. As these
general upfield shifts are indeed observed in both the
PPh3 and trpy* ligands, anisotropic deshielding may be
the cause. Notably, the Ha protons are expected to be
unique since the phenyl rings of the PPh3 may freely
rotate once they clear the plane of the trpy* ligand. The
downfield shift for Ha of 3 and 4 may be due to the
anisotropic deshielding from the phenyls in the pockets.
Finally, it has been observed that the two trans-
triphenylphosphine ligands of 4 deshield the trpy*
protons somewhat less than the one triphenylphosphine
of 3. This may be due, in part, to the slightly different
second phosphorus nuclei. Since the two-bond Pꢀ
/
Ruꢀ
/
P? coupling is much larger than the PꢀC couplings, the
/
higher-order pattern is a triplet rather than a doublet-of-
doublets or a pentuplet as only the algebraic sum of the
two Pꢀ/C couplings can be measured across the outer
line of the triplet. For 4, the coupling constant values are
1
ipsoꢂ
/
j JPꢀCiꢁ3
/
JPꢀCijꢂ
/
39.2
Hz,
3
orthoꢂ
/
j JPꢀCjꢁ4
/
JPꢀCjjꢂ
/
10.3 Hz, metaꢂ
/
j JPꢀCkꢁ5
/
JPꢀCkjꢂ
/
2
4
9.0 Hz, and paraꢂ
/
j JPꢀClꢁ6
/
JPꢀCljꢂ
/
0 Hz. These values
are nearly the same as those that were observed for the
analogous trpy complex except that in 4? we were able to
measure the para coupling at 1.6 Hz [23]. Finally, there
were no important changes in the JPꢀC for phenyl
carbons with structural position (meridional or axial
relative to trpy*) but, for a given complex, the value for
the meta carbon is always smaller than the ortho carbon
value. This observation allowed for the absolute assign-

S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ
/115
111
ment of phenyl protons via a carbonꢀ
experiment.
/
proton HETCOR
chloride and four molecules of toluene. It should be
noted that in this treatment, the contribution of the
solvent molecules is collective and not as individual
atoms. Hence, the atom list does not contain the atoms
of the solvent molecules.
Freshly prepared samples of trans-[RuCl2(tr-
py*)(PPh3)] had 31P NMR chemical shifts of about 45
ppm with linewidths up to 1000 Hz (see Table 3). After
sitting for a day or two, the linewidth decreased to 10 Hz
and the chemical shift increased to 46.04 ppm. While
this shift compares well to the reported value of 46.45
ppm in the literature [21], there is no previous mention
of the initial wide line nor the decrease in linewidth when
the complex ages in CD2Cl2. Again, we presently have
no explanation for this behavior. Interestingly, 2? had a
line width of 48 Hz when freshly prepared but this
decreased to 37 Hz after 3 days and did not change
thereafter. The chemical shift of 2? (44.66 ppm) did not
change with aging.
Our 31P NMR chemical shift of 44.20 ppm for 3 in
CD2Cl2 is similar to the 44.59 ppm value of Le Bozec
and coworkers [21]. The linewidth for 3 was typically 17
Hz and did not change over time. The corresponding
trpy complex 3? had a chemical shift of 41.1 ppm and a
linewidth of 1.5 Hz. When a second triphenylphosphine
is added to 3 or 3? to form 4 or 4?, the 31P NMR
chemical shifts decrease to 22.66 and 21.21 ppm,
respectively.
Compound 4 co-crystallized with a molecule of
methylene chloride disordered in the unit cell. Again,
Squeeze/Platon [35] was applied to resolve the disor-
3
˚
dered solvent. Within the 804.5 A of void space
accessible to solvent molecules, a total of 175 electrons
were calculated, compared to 168 electrons predicted for
the presence of four molecules of methylene chloride.
The ruthenium atoms in each structure reside in a
distorted octahedral environment with a trpy* bite
angle, N(1)ꢀ
/
RuꢀN(3), of 159.44(6)8 and 157.9(2)8 for
/
complexes 3 and 4, respectively. These bite angles are
consistent with those found for other (trpy)ruthenium
complexes, namely trans-[RuCl(trpy)(PPh3)2](BF4),
157.9(3)8 [23], trans-[Ru(NO2)(trpy)(PMe3)2](ClO4),
158.3(2)8 [36], trans-[Ru(H2O)(trpy)(PEt3)2](ClO4)2,
158.3(3)8 [37], and trans-[Ru(NO2)(trpy)(PPh3)2](PF6),
156.9(5)8 [38]. The deviations from the ideallized 1808
attributed to an octahedral geometry are similar to those
that have been observed for trpy and are attributed to
the geometrical constraints of the trpy* backbone. The
We note that Meyer and coworkers [27] found a large
shift difference for the trans- and cis-[RuCl2(trpy)(P(p-
C6H4CH3)3)] isomers in CH3CN (referenced to 15%
H3PO4 in D2O). They reported chemical shifts of 27.3
and 41.6 ppm, respectively. We suspect that the litera-
ture value of their trans-[RuCl2(trpy)(P(p-C6H4CH3)3)]
complex may be in error.
Ruꢀ
to 2.0702(17) A in 3 and 1.957(5) to 2.094(4) A in 4 with
the shortest RuꢀN bond distance in both complexes
between the ruthenium and the nitrogen of the central
pyridine ring of trpy. Asymmetric bond lengths exist
between the ruthenium center and terminal nitrogens of
/
N(i) (iꢂ
/
1ꢀ
/
3) bond lengths range from 1.9418(15)
˚
˚
/
the trpy* ligand in both 3 and 4; however, all these Ruꢀ
N bond distances are typical of other (trpy)ruthenium
complexes: 1.952(9)ꢀ2.098(6) [36ꢀ39].
For complex 4, the P(1)ꢀRuꢀP(2) bond angle of
177.73(6)8 also deviates slightly from linearity (1808). A
normal range for trans-(PꢀRuꢀP) angles is given as
175.1(1)8 to 178.2(2)8 for PMe3 [36], PEt3 [37], PPr3 [39],
and PPh3 [23,40] complexes. Notably, the PꢀRuꢀ
/
3.5. X-ray structural analyses
/
/
/
/
The molecular structures of 3 and 4 have been
established by X-ray crystallography (Figs. 4 and 5).
The crystal and structure refinement data are summar-
ized in Table 4 and selected bond angles and lengths are
listed in Tables 5 and 6 for complexes 3 and 4,
respectively. Crystals of 3 and 4 were grown using the
/
/
/
/P
bond axis appears to bend in the direction of the
chloride ligand, implying that this region is less sterically
crowded than the region around the trpy* ligand.
double vial diffusion technique in CH2Cl2ꢀtoluene
/
solutions. While complex 3 crystallized in a molecular
unit, the overall structure of complex 4 consists of an
array of ordered ruthenium cations and anions (PF6ꢃ) in
a 1:1 stoichiometry along with solvent of crystallization.
Compound 3 co-crystallized with one-half of a
molecule of dichloromethane and one molecule of
toluene in the unit cell. The dichloromethane was both
positionally and occupationally disordered while the
toluene was positionally disordered in the unit cell.
Squeeze/Platon [35] was applied to resolve the disor-
A comparison of the ORTEP representations of 3 and 4
(Figs. 2 and 3, respectively) indicates that the phenyl
rings of the triphenylphosphine ligand(s) align in similar
positions about the trpy* ligand regardless of whether
one or two PPh3 ligands is coordinated to the ruthenium
center. By defining a reference plane for 3 as the plane of
the trpy* backbone (N1, N2 and N3), the ruthenium
atom and meridional chloride atom, we have examined
the angle that the plane of the phenyl rings of PPh3 make
with this reference. The planes containing each of the
phenyl rings of the triphenylphosphine ligands are
described by the phosphorous atom, the ipso-carbon
atom of the phenyl ring as well as the adjacent (ortho)
carbons of the phenyl ring. Using this scheme, it is
3
˚
dered solvent. Within the 1345.5 A of void space
accessible to the solvent molecules, a total of 239
electrons were calculated, compared to the 284 electrons
predicted for the presence of two molecules of methylene

112
S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ115
/
Fig. 4. Molecular structure of cis-[Ru(trpy*)(PPh3)Cl2] (3) (drawn at 30% probability), showing atomic labeling scheme. Hydrogen atoms are
omitted for clarity.
Fig. 5. Molecular structure of trans-[Ru(Cl)(trpy*)(PPh3)2]ꢁ cation (4) (drawn at 30% probability), showing labeling scheme. Hydrogen atoms are
omitted for clarity.

S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ
/115
113
Table 4
Crystal data and structural refinement for cis-[RuCl2(trpy*)(PPh3)] (3)
and trans-[RuCl(trpy*)(PPh3)2]PF6 (4)
Table 5
˚
Selected bond lengths (A) and angles (8) for cis-[RuCl2(trpy*)(PPh3)]
(3)
3
4
Rutheniumꢀ
/
ligand distances
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
/
N(1)
N(2)
N(3)
2.0610(17)
1.9418(15)
2.0702(17)
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
/
P(1)
2.2803(4)
2.4448(5)
2.4507(5)
Empirical formula
Formula weight
Temperature (K) 173(2)
C
45H50Cl2N3PRu
C63H65ClF6N3P3Ru
1207.61
173(2)
/
/Cl(1)
835.82
/
/Cl(2)
Phosphorousꢀ
/
carbon distances
1.8310(19)
1.837(2)
˚
Wavelength (A)
Crystal system
Space group
Unit cell dimen-
sions
0.71073
monoclinic
P21/c
0.71073
monoclinic
P21/n
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
/
C(11)
C(21)
C(31)
/
/
1.836(2)
Angles around the ruthenium atom
˚
N(2)ꢀ
N(2)ꢀ
N(1)ꢀ
N(2)ꢀ
N(1)ꢀ
N(3)ꢀ
P(1)ꢀRu(1)ꢀ
Cl(1)ꢀRu(1)ꢀ
/
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Cl(1)
Cl(2)
/
N(1)
N(3)
N(3)
79.74(6)
79.75(6)
159.44(6)
N(2)ꢀ
N(1)ꢀ
N(3)ꢀ
N(2)ꢀ
N(1)ꢀ
N(3)ꢀ
92.188(17) P(1)ꢀRu(1)ꢀ
89.403(17)
/
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
/
P(1)
P(1)
92.70(4)
91.32(4)
91.06(4)
85.73(4)
88.85(4)
88.20(4)
178.361(19)
a (A)
13.7888(7)
24.3826(13)
13.4235(7)
90
11.9588(7)
19.1204(11)
28.8601(17)
90
˚
/
/
/
/
b (A)
˚
c (A)
/
/
/
/
P(1)
/
/
Cl(1) 174.50(5)
Cl(1) 97.63(5)
Cl(1) 102.69(4)
/
/
Cl(2)
Cl(2)
Cl(2)
a (8)
b (8)
g (8)
/
/
/
/
101.9930(10)
90
92.1080(10)
90
/
/
/
/
3
˚
/
/
/
/
Cl(2)
V (A )
4414.6(4)
4
1.258
6594.6(7)
4
1.216
/
/
Z
Density (calcu-
lated) (Mg mꢃ3
Angles around the phosphorous atoms
)
Absorption coef- 0.545
C(11)ꢀ
C(11)ꢀ
C(31)ꢀ
/
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
/
C(31)
C(21)
C(21)
100.32(9)
99.71(9)
108.82(9)
C(11)ꢀ
C(31)ꢀ
C(21)ꢀ
/
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
/
Ru(1) 122.13(6)
Ru(1) 109.21(6)
Ru(1) 115.13(6)
0.405
2496
/
/
/
/
ficient (mmꢃ1
F(0 0 0)
)
/
/
/
/
1736
Crystal size (mm3) 0.60ꢄ
/
0.40ꢄ
/
0.40
0.40ꢄ/0.20ꢄ0.20
/
Symmetry transformations were used to generate equivalent atoms.
Theta range for
data collection (8)
Index ranges
1.67ꢀ
/
28.30
1.41ꢀ25.00
/
ꢃ
/
165
285k 5
l 517
21 205
/h 5
/
13, ꢃ
/
ꢃ/135/h 5
/
13, ꢃ
/
225
/
Table 6
/
/31, ꢃ
/175
/
k 522, ꢃ
/
/335
/l 5
/33
˚
Selected bond lengths (A) and angles (8) for trans-[RuCl(tr-
py*)(PPh3)2]PF6 (4)
/
Reflections col-
lected
26 623
10 868 (Rint
25.008 (3.5%)
Rutheniumꢀ
/
ligand distances
Independent re-
flections
9260 (Rint
ꢂ
/0.0251)
ꢂ0.0686)
/
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
/
N(1)
N(2)
N(3)
2.094(4)
1.957(5)
2.076(4)
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
/
P(1)
P(2)
Cl(1)
2.4070(19)
2.3779(18)
2.4507(15)
/
/
Completeness to 28.308 (84.4%)
theta
/
/
Phosphorousꢀ
/
carbon distances
Absorption cor-
rection
semi-empirical/SA-
DABS
0.8115 and 0.7358
semi-empirical/SADABS
0.9233 and 0.8547
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
/
C(11)
C(21)
C(31)
1.840(6)
1.824(7)
1.837(6)
P(2)ꢀ
P(2)ꢀ
P(2)ꢀ
/
C(41)
C(51)
C(61)
1.831(6)
1.828(7)
1.834(6)
/
/
Max. and min.
transmission
Refinement meth- Full-matrix least-
/
/
Angles around the ruthenium atom
Full-matrix least-squares
on F2
10 868/20/704
squares on F2
P(1)ꢀ
P(2)ꢀ
P(2)ꢀ
P(1)ꢀ
Cl(1)ꢀ
P(1)ꢀRu(1)ꢀ
Cl(1)ꢀRu(1)ꢀ
N(2)ꢀRu(1)ꢀN(3)
/
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
N(3)
N(3)
/
P(2)
177.73(6)
88.17(6)
P(1)ꢀ
P(1)ꢀ
/
Ru(1)ꢀ
/
Cl(1)
90.51(6)
89.48(15)
107.43(15)
90.48(16)
79.1(2)
od
/
/
Cl(1)
N(1)
N(2)
/
Ru(1)ꢀ
/N(1)
Data/restraints/
parameters
Goodness-of-fit
on F2
9260/0/478
/
/
89.15(15) Cl(1)ꢀ
91.05(16) P(2)ꢀRu(1)ꢀ
173.31(14) N(1)ꢀRu(1)ꢀ
92.14(14) P(2)ꢀRu(1)ꢀN(3)
94.62(13) N(1)ꢀRu(1)ꢀN(3)
78.82(19)
/
Ru(1)ꢀ
N(2)
N(2)
/N(1)
/
/
/
/
1.005
1.080
/
/
N(2)
/
/
/
/
/
/
89.81(14)
157.9(2)
Final R indices
R1ꢂ
0.0859
R1ꢂ0.0362, wR2ꢂ
0.0889
/0.0307, wR2ꢂ
/
R1ꢂ
0.1712
R1ꢂ0.1177, wR2ꢂ
0.1895
1.214 and ꢃ
/
0.0748, wR2ꢂ
/
/
/
/
/
[Iꢁ2s(I)]
/
/
/
R indices (all
/
/
/
/
data)
Angles around the phosphorous atoms
Largest diff. peak 0.479 and ꢃ
/0.374
/0.855
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
Ru(1)ꢀ
/
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(2)ꢀ
P(2)ꢀ
P(2)ꢀ
/
C(11)
C(21)
C(31)
C(41)
C(51)
C(61)
116.9(2)
120.9(2)
108.7(2)
111.9(2)
112.2(2)
121.2(2)
C(11)ꢀ
C(11)ꢀ
C(21)ꢀ
C(41)ꢀ
C(41)ꢀ
C(51)ꢀ
/
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(2)ꢀ
P(2)ꢀ
P(2)ꢀ
/
C(21)
C(31)
C(31)
C(51)
C(61)
C(61)
101.0(3)
105.2(3)
102.1(3)
109.6(3)
100.1(3)
100.5(3)
ꢃ3
˚
and hole (e A
)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
observed that the three phenyl rings on P of complex 3 are
oriented at angles of 85.54(0.07)8, 27.78(0.09)8 and
18.48(0.06)8 from the reference plane (for ipso-carbons
from C(11) and proceeding clockwise about the P atom).
By defining similar reference and phenyl ring planes, we
have observed that the three phenyl rings on P(1) of 4 are
oriented at angles of 85.54(0.22)8, 16.36(0.14)8 and
50.86(0.19)8, 16.36(0.14)8 (from ipso-carbon C(21) and
/
/
/
/
proceeding clockwise around the P(1) atom) and the
three rings on P(2) are oriented at angles of 79.16(0.18)8,
23.68(0.14)8, 24.28(0.20)8 from the reference plane (for
ipso-carbon C(61) and proceeding clockwise about the

114
S.B. Billings et al. / Inorganica Chimica Acta 355 (2003) 103ꢀ115
/
P(2) atom). Notably, in the structures of both 3 and 4 one
of the phenyl rings lies between the chlorine atom and
one of the terminal pyridine rings of trpy*. The second of
the phenyl rings lies nearly parallel to the reference
surface between the central and terminal pyridyl rings of
trpy* and the third phenyl ring lies between the other
terminal pyridyl ring and the chlorine atom.
For the structure of 4, the phenyl rings of (C(21) and
C(61)), (C(31) and C(51)) and (C(11) and C(41)) exist as
nearly eclipsed pairs. Geometric considerations indicate
that each of these phenyl rings may be involved in p-
stacking with the trpy* ligand as they are within the
Acknowledgements
This work was supported by Research Corporation
(CC4252). S.B. was funded by a 1997 Villanova
University Chemistry Department Summer Research
Fellowship. The authors also wish to thank Ms. Pooja
Aggarwal for assistance in the synthesis of the ruthe-
nium complexes.
References
˚
prescribed approximately 3.6 A distance [41]. Finally, it
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