The effect of ancillary ligands on intramolecular proton-hydride (NH?HIr) bonding in complexes of iridium(III)

Article abstract of DOI:10.1016/S0022-328X(00)00238-2

The reaction of the trihydride IrH₃(PPh₃)₃ with HBF₄ in the presence of pyridinethione (SpyH) affords a dihydrido SpyH complex [IrH₂(η¹-SpyH)(PPh₃)₃](BF ₄) (1). Complex 1 undergoes a substitution of one of the PPh₃ ligands by another SpyH to produce [IrH₂(η¹-SpyH)₂(PPh₃) ₂](BF₄) (2). Complex 2 slowly eliminates a dihydrogen molecule to form a known monohydrido complex [IrH(η¹-SpyH)(η²-Spy)(PPh₃) ₂](BF₄) under mild conditions. [IrH(CO)(η¹-SpyH)₂(PPh₃) ₂](BF₄)₂ (3) is obtained from the reaction of known IrH₃(CO)(PPh₃)₂ with HBF₄ in the presence of SpyH. The properties of the NH?HIr proton-hydride bonds (also known as dihydrogen bonds) in complexes 1-3 are characterized in solution by T₁ NMR measurements and in the solid state by IR measurements and single crystal X-ray diffraction. They are compared with properties of three related complexes to understand the effect of the ancillary ligands on the strength of this non-classical bond. Stronger proton-hydride bonds are formed in complexes with PCy₃ co-donor ligands in comparison with complexes with PPh₃ co-donor ligands. The strength of proton-hydride bonds is decreased in complexes containing more PPh₃ or CO ligands. The best indicators of H?H bond strength are Av values from IR and the N?Ir distance from the X-ray structures.

Full text of DOI:10.1016/S0022-328X(00)00238-2

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 609 (2000) 110–122
The effect of ancillary ligands on intramolecular protonꢀhydride
(NH···HIr) bonding in complexes of iridium(III)
Sung Han Park a,1, Alan J. Lough a, Glenn P.A. Yap b,2, Robert H. Morris a,*
a Department of Chemistry, Uni6ersity of Toronto, 80 St. George Street, Toronto, Ont., Canada M5S 3H6
b Department of Chemistry, Uni6ersity of Windsor, Windsor, Ont., Canada N9B 3P4
Received 19 February 2000; received in revised form 16 April 2000
Abstract
The reaction of the trihydride IrH3(PPh3)3 with HBF4 in the presence of pyridinethione (SpyH) affords a dihydrido SpyH
complex [IrH2(h1-SpyH)(PPh3)3](BF4) (1). Complex 1 undergoes a substitution of one of the PPh3 ligands by another SpyH to
produce [IrH2(h1-SpyH)2(PPh3)2](BF4) (2). Complex 2 slowly eliminates a dihydrogen molecule to form a known monohydrido
complex [IrH(h1-SpyH)(h2-Spy)(PPh3)2](BF4) under mild conditions. [IrH(CO)(h1-SpyH)2(PPh3)2](BF4)2 (3) is obtained from the
reaction of known IrH3(CO)(PPh3)2 with HBF4 in the presence of SpyH. The properties of the NH···HIr protonꢀhydride bonds
(also known as dihydrogen bonds) in complexes 1–3 are characterized in solution by T1 NMR measurements and in the solid state
by IR measurements and single crystal X-ray diffraction. They are compared with properties of three related complexes to
understand the effect of the ancillary ligands on the strength of this non-classical bond. Stronger protonꢀhydride bonds are
formed in complexes with PCy3 co-donor ligands in comparison with complexes with PPh3 co-donor ligands. The strength of
protonꢀhydride bonds is decreased in complexes containing more PPh3 or CO ligands. The best indicators of H···H bond strength
are Dw values from IR and the N···Ir distance from the X-ray structures. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Protonꢀhydride bond; Pyridinethione; SpyH; Trihydride; Dihydrogen; Iridium
the tautomer of 2-mercaptopyridine, or 2-thiazo-
lidinethione or 2-benzothiazolethione; (ii) a reaction of
IrH5(PCy3)2, with pyridiniumthiol (HSpyH+) [1]. The
latter method, when conducted using an excess of hy-
drogen bond donor ligand and acid, afforded species of
the type [Ir(SpyH···H···HpyS)(SpyH)2(PCy3)]2+ and
[Ir(SpyH···H···HpyS)(h2-Spy)(PCy3)]+ (6 in Fig. 1)
[2].First the route to the known triphenylphosphine
complexes of iridium containing proton hydride bonds
will be reviewed. The neutral trihydrido aminopyridine
(pyNH2) complex IrH3(pyNH2)(PPh3)2 (I) [7] was pre-
pared from IrH5(PPh3)2 with 2-aminopyridine under
very mild conditions (room temperature (r.t.) for sev-
eral hours) according to Eq. (1). Due to the difficulty in
obtaining IrH5(PPh3)2 in high yield, a trihydride
IrH3(PPh3)3 was used in an attempt to make an
analogous trihydrido species (I, LꢀNHꢁSpyH) under
similar conditions [3]. The result was the chelation of
the pyridinethione ligand to give a complex of type II in
Eq. (1). As noted in our earlier studies, the protonation
of II with an acid in the presence of proton donor
1. Introduction
Our group has been investigating the structural types
of NH···HIr protonꢀhydride bonds [1–6] since their
existence was recognized by some of us and by Crabtree
and co-workers [7–9] in 1994. Related OH···HIr inter-
actions were identified by Stevens et al. [10] and Crab-
tree and co-workers [7] and labelled ‘dihydrogen bonds’
[11]. The object of the current study is to prepare
triphenylphosphine analogs to the tricyclohexylphos-
phine complexes already characterized [1,2,4] (e.g. com-
plexes 5 and 6 in Fig. 1). Complexes of the type 5 are
obtained by two different routes: (i) a substitution of
weakly coordinated solvent molecules [4] in
[IrH2(solvent)2(PCy3)2]+ with pyridinethione (SpyH),
* Corresponding author. Tel./fax: +1-416-978-6962.
E-mail address: rmorris@chem.utoronto.ca (R.H. Morris).
1 Present address: Department of Chemistry, Stanford University,
Stanford, CA 94305, USA.
2 Present address: X-Ray Laboratory, 401 Pavillon d’Iorio, 10
Marie Curie Avenue, University of Ottawa, Ottawa, Ont., Canada.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00238-2

S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
111
ligand (SpyH) was attempted to obtain complexes like 5
or 6 but containing PPh3. However, the reaction pro-
duced the monohydrido species 4 (Fig. 1) [3]. Another
possible synthetic approach is the use of IrH3(PPh3)3 in
the direct reaction with HSpy and an acid. This will be
described in the first part of this study.
influence the strength of this non-classical hydrogen
bond.
2. Results and discussion
2.1. Synthesis of [IrH2(p1-SpyH)(PPh3)3](BF4) (1)
The reaction of fac-IrH3(PPh3)3 with tetrafluoroboric
acid etherate in the presence of pyridine-2-thione in
dichloromethane or chloroform gives a product iden-
tified as [IrH2(SpyH)(PPh3)3](BF4) (1) according to Eq.
(2). Complex 1 is isolated in 91% yield as a yellow
microcrystalline solid which is slightly soluble in
CHCl3, toluene, benzene or acetone, but very soluble in
CH2Cl2. Complex 1 has been also prepared from the
mixture of fac- and mer-isomers of the trihydride which
is conveniently obtained in similar yield from iridium
trichloride according to a method similar to that of
Chatt et al [12].
(1)
In the second part of this study, a synthetic approach
to hydrido carbonyl complexes containing the SpyH
hydrogen bond donor group is described. A carbonyl
ligand might be a weaker hydrogen bond acceptor than
hydride and may not interfere with the formation of
SpyH···HIr bonds. On the other hand, it is a strong
p-acid and could influence the strength of the proton
hydride bond. Some preliminary results are presented.
Finally, in the last part of this study, the features of
the proton hydride bonds in the six pyridinethione
complexes described previously or prepared in the cur-
rent study will be compared to discern factors that
(2)
2.2. Characterization of [IrH2(p1-SpyH)(PPh3)3](BF4)
(1)
Complex 1 has been characterized by microanalysis,
1
NMR techniques (31P- and H-NMR, VT–T1 measure-
ment), infrared spectroscopy, and an X-ray diffraction
study. In CDCl3 the 31P{1H}-NMR spectrum of 1
consists of two signals at 2.23 as a doublet and −0.93
ppm as a triplet with an intensity ratio of 2:1. The
appearance of these resonances is monitored by
31P{1H}-NMR in comparison with the disappearance
of the singlet at 10 ppm for the parent trihydride. The
pattern of the new resonances indicates the formation
of a single isomer with three phosphine ligands in two
different magnetic environments. The proton NMR
spectrum of 1 in CDCl3 contains assignable peaks for
the protons on the pyridine ring, the phenyl groups as
well as the hydrides. Peaks for the pyridine ring protons
are overlapping with those for the phenyl ring protons
in the region from 7.8 to 6.4 ppm. The patterns of the
resonances of the two inequivalent hydrides are distinc-
tive at −12.7 and −15.8 ppm. The former appears as
a doublet of triplet of doublets due to couplings of
trans JPH (116 Hz), cis JPH (22 Hz), and cis JHH (3.6
Hz) while the latter appears as a pseudo quartet of
doublets due to couplings with three cis-phosphorus
nuclei and a cis-hydride nucleus. Finally the NH pro-
ton resonance appears at 10.9 ppm as a broad singlet.
Other possible isomers such as fac-cis-1a and mer-
trans-1b depicted in Fig. 2 have not been observed in
the product. Probably the former is less favored be-
Fig. 1. Iridium(III) complexes possessing one or two proton hydride
bonding units.
Fig. 2. Possible isomers other than 1 that might form in reaction 2.

112
S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
shorter T1min of 0.18 s is assigned to the resonance for
the hydride (Ha) cis to the SpyH ligand. The relaxation
rate (5.6 s−1) for this T1 value is attributed to two PPh3
b
protons (1.0 s−1, 2.4 A), cis-hydride (H ) (0.7 s−1, 2.3
,
A) and the NH proton (3.9 s−1). The calculation [13]
,
a
,
gives the H ···H(N) distance of ca. 1.71 A from the
T1min of the hydride (Ha). Using a T1min of 0.22 s for the
Fig. 3. Comparison of the hydride and NH resonances and their
T1min for 1.
NH proton and the sole relaxation rate contribution
(3.2 s−1) from the hydride, after subtraction of a
cause of steric congestion caused by the three large
phosphine ligands and the latter, because of the insta-
bility of trans-hydrides. After ca. four weeks, 1 under-
goes a partial isomerization in the solid state under
laboratory fluorescent light conditions. The isomeriza-
tion yield is about 10% as judged by the intensity ratio
in the proton and phosphorus NMR spectra. The iso-
merization product is proposed to be the trans-hydride
1b based on the following NMR characterization in
CD2Cl2. The 31P{1H}-NMR spectrum of the isomeriza-
tion product exhibits resonances characteristic of a
typical mer-phosphine complex as a doublet (J=15.67
Hz) and a triplet (J=15.55 Hz) at −10.05 and −
17.32 ppm, respectively. Complex 1a would also give
this pattern. The proton NMR spectrum contains a
hydride resonance at −19.75 ppm as a doublet of
triplets with coupling constants of 22.4 and 8.85 Hz due
to coupling to the phosphorus nuclei in two different
cis-environments. Two mutually trans-hydrides are
magnetically equivalent with respect to these three cis-
phosphorus ligands and a cis-pyridinethione ligand.
The NH resonance of the monodentate SpyH ligand
appears at 12.5 ppm as a broad singlet with half the
intensity of the hydride resonances. The fact that the
spectrum lacks a resonance with a large trans-PH cou-
pling suggests that the fac-isomer 1a is not formed. The
intensity of the hydride and NH proton resonances of
1b relative to those of 1 is about 10% after a month and
no further change is observed.
contribution of 1.4 s−1 for N at 1.0 A, the H···H
14
,
,
distance of ca. 1.77 A is obtained.
H/D exchange experiments have been carried out at
r.t. with D2 gas or CH3OD. Exposure of a CD2Cl2
solution of 1 to D2 gas at 1 atm for 3 min resulted in no
significant changes in the intensities of the NH and IrH
resonances in the proton NMR spectrum. This con-
trasts with the reactivity of 5 where extensive exchange
of ND for NH and IrD for IrH was observed under
comparable conditions [1]. Isotopic shifts are observed
when this solution is treated with an excess of CH3OD,
a result of the deuteration at the NH group. After 15 h
in the presence of CH3OD the pseudoquartet resonance
at −15.7 ppm for the hydride trans to the SpyH ligand
becomes a superimposed multiplet (15 lines evenly
spaced) centered at −15.48 ppm while the doublet of
triplet of doublet resonance at −12.7 ppm for the
other hydride is broadened by unresolved resonances
due to isotopomers. Similarly, in the 31P{1H}-NMR
spectrum, the resonance at −0.66 ppm (triplet) for the
phosphine ligand trans to the hydride is unchanged
while that of the other two equivalent phosphorus
nuclei has shifted (Dl=0.079) from 1.72 (doublet) to
1.82 ppm (doublet). A similar isotopic perturbation
with CH3OD has been described for [IrH(h1-SpyH)(h2-
Spy)(PPh3)2](BF4) (4) [3].
2.3. Formation of [IrH2(p1-SpyH)2(PPh3)2](BF4) (2)
The solid state IR spectrum of 1 contains characteris-
tic bands corresponding to w(IrꢀH) and w(NH). Bands
for w(IrꢀH) at 2063 and 2197 cm−1 (KBr) are compara-
ble to those (2214; 2137, 2120 cm−1) for the pro-
tonꢀhydride-bonded complexes [IrH(h1-SpyH)(h2-Spy)-
(PPh3)2](BF4) 4, and [IrH2(h1-SpyH)2(PCy3)2](BF4) 5,
respectively [1,5]. The w(NH) of coordinated SpyH in 1
appears as a broad band at 3225 cm−1. This band is
similar to that (3236 cm−1) of 4, but at higher
wavenumbers than that (3111 cm−1) of 5. This proba-
bly indicates that the IrꢀH···HꢀN interactions are
weaker in 1 and 4 than those in 5.
The minimum T1 (T1min) values for the two hydrides
and the NH proton of 1 have been obtained at 233 K
at 400 MHz. These are shown in Fig. 3 with a proposed
structure of 1, the one found by X-ray diffraction (see
below). The T1 minima are 0.18 and 0.23 s for the
hydrides and 0.22 s for the NH proton in CD2Cl2. The
One of the triphenylphosphine ligands in [IrH2-
(SpyH)(PPh3)3](BF4) (1) is replaced by another pyri-
dine-2-thione ligand at r.t. over a period of one week.
Thus, the product is a bis(triphenylphosphine) complex
containing two SpyH proton donor groups. This is
formulated as [IrH2(h1-SpyH)2(PR3)2](BF4) (2) (R=
Ph) which is the triphenylphosphine analog to 5 (R=
Cy) (Fig. 1). However, 2 is a difficult complex to isolate
because it undergoes a further reaction to eliminate a
dihydrogen molecule (Scheme 1).
Based on the following NMR observations, the struc-
ture of the species formed in this H2 elimination
reaction is proposed to be trans-[IrH(h1-SpyH)-
(h2-Spy)(PPh3)2](BF4) (4%) which is the trans-isomer of 4
that contains both chelating pyridinethiolate and
monodentate pyridinethione ligands. The hydride reso-
nance of 4% at −16.68 ppm is a triplet (JPH=12.21 Hz)
and the NH proton resonance at 11.91 ppm is a broad

S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
113
singlet. These resonances are compared with those for 4
at −17.78 ppm as doublet of doublets for the hydride
(JPH=14.3 Hz) and 11.86 ppm as a broad singlet for
the NH proton [3]. Although there are two possible
trans isomers (i.e. the hydride trans to S or N of the
chelate ring), Scheme 1 shows the one with the sulfur
atom trans to the hydride, which would result from the
stereospecific elimination of H2 from 2.
Complex 4% is apparently an intermediate species
observed by NMR spectroscopy in the transformation
of 2 in CDCl3 to the cis-product, 4 (Scheme 1). Com-
plex 4% has been also observed previously as an interme-
diate in the preparation of 4 from the reaction of the
dihydride IrH2(h2-Spy)(PPh3)2 with tetrafluoroboric
acid in the presence of pyridine-2-thione [3].
2.4. Characterization of [IrH2(p1-SpyH)2(PPh3)2](BF4)
(2)
Yellow crystals of 2 were obtained by fractional
crystallization of the mixture of products from the
reaction of 1 with one equivalent pyridine-2-thione by
layering in CHCl3 with ether. The NMR resonances for
2 are very similar to those for 5, a PCy3 analog (Table
1). In the proton NMR spectrum in CD2Cl2 the reso-
nances for the NH protons and hydrides appear at
11.70 ppm as a broad singlet and −15.95 ppm as a
triplet, respectively. The 31P{1H}-NMR spectrum con-
tains a singlet at 9.4 ppm. These results are consistent
with the equivalence of ligand groups of two SpyH
ligands, two hydrides and two phosphorus ligands. The
short T1min of 0.16 s for the NH protons and 0.20 s for
the hydrides have been obtained for a solution of 2 in
CD2Cl2 at 193 K, 400 MHz. These T1min values and the
relaxation rate contributions are compared with those
for 5 in Table 1. The results suggest that the solution
structure of 2 is very similar to that of 5. The X-ray
structure determination of 2 supports this conclusion
(see Section 2.6).
Scheme 1. Transformation of 1 to 4 via 2 and 4%, the trans isomer of
4.
Table 1
Comparison of the selected NMR a and T1min calculations for 2 and
5
2
5
l (NH)
11.70 (br s)
0.16 s (193 K)
6.2
12.18 (br s)
0.18 s (233 K)
5.6
T1min (observed)
Total relaxation rate (s−1
)
14N contribution (s−1
)
1.4
1.4
,
(1.0 A)
Other contribution b (s−1
)
1.4
,
(2.1 A: one H of PPh3)
Sole contribution of H(Ir) 3.4
(s−1
T1 (correct) (s)
3.1
)
0.28
0.23
,
d(HH) from T1(NH) (A)
1.7490.05
1.6890.05
l(IrH) (t, J=15.3 Hz)
T1min (observed) (s)
−15.95
0.20 (193 K)
5.0
−18.28
0.17 (233 K)
5.9
Total relaxation rate (s−1
)
2.5. Synthesis of [IrH(CO)(SpyH)2(PPh3)2](BF4)2 (3)
,
,
Cis-hydride contribution
0.9 (2.2 A)
0.5 (2.4 A)
c
(s−1
)
PR3 proton contributions
1.5
1.7
Triphenylphosphine complexes containing carbonyls
are often prepared from the reaction of commercially
available transition metal chlorides with reactive or-
ganic carbonyl-containing compounds such as alde-
hydes or alcohols in the presence of a strong base [14].
In our attempt, a tris(triphenylphosphine)hydrido com-
plex of Ir(III) was reacted with sodium hydroxide as a
base and methanol as a carbonyl source, according to
Eq.(3). A mixture of hydrido species consisting of a
major (ca. 90%) and minor (ca. 10%) species was
obtained. The hydride resonances for the major species
in CDCl3 appeared at −10.10 and −10.55 ppm as a
triplet of doublets (JPH=16.6 Hz, JHH=4.6) and a
triplet of triplets (JPH=19.2 Hz, JHH=4.2), respec-
tively, with an intensity ratio of 2:1. In the 31P{1H}-
NMR spectrum there is a singlet at 16.29 ppm for the
d
(s−1
)
(2.2 and 2.3 A)
Sole contribution of H(N) 2.6
(s−1
T1 (correct) (s)
(2.2 and 2.2 A)
3.7
,
,
)
0.37
1.8290.05
ca. 1.78
0.27
1.7290.05
ca. 1.70
,
d(HH) from T1(IrH) (A)
Average d(HH) from T1
,
(A)
31P{1H}
9.4 (s)
8.21 (s)
a Chemical shifts in ppm, NMR measured in CD2Cl2 at 400 MHz.
Relaxation rate contributions and d(HH) calculations done using the
approach of Desrosiers et al. [13].
b Contribution from PCy3 protons in 5 is not added because the
position of the hydrides is uncertain.
c The typical distance between two cis-hydrides is assumed to be
,
2.4 A in 5.
d Two trans-PR3 groups each with two CH protons near to the
hydrides.

114
S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
Fig. 4. Characteristic NH stretching wavenumbers for 3 (Nujol, KBr).
(5)
major species. The presence of a carbonyl ligand is
confirmed by a strong w(CO) band at 2077 cm−1. These
NMR and IR observations are consistent with a trihy-
drido carbonyl complex IrH3(CO)(PPh3)2 [15]. The mi-
nor species was not identified.
The IR spectrum of 3 in Nujol provides evidence for
a carbonyl ligand and two types of NH units in the
SpyH ligands. There is a strong band at 2044 cm−1 for
the carbonyl ligand. There are two NH stretching fre-
quencies at 3287 (sharp) and 3247 cm−1 (very broad)
(Fig. 4). The NHa···HIr interaction is probably respon-
sible for the broadening of the peak at lower wavenum-
ber. The NHa stretching frequency of 3247 cm−1 in 3 is
a little lower than that of non-hydrogen bonding SpyH
at 3376 cm−1 [16]. The Dw value of 129 cm−1 indicates
that the NHa···HIr interaction in 3 is relatively weak.
Comparisons with other complexes will make this
clearer in discussion further on. Another band at 3287
cm−1 is due to the NHb unit which is not involved in
protonꢀhydride bonding. The Dw value of this band in
comparison with w(NH) of non hydrogen bonding
SpyH is 89 cm−1. This difference can be attributed to
the perturbation in w(NH) caused by the coordination
of the ligand. However, it is difficult to confirm this
since there is a very weak NꢀH···F hydrogen bond
involving one of the BF−4 counterions revealed by
X-ray analysis (see later). For comparison purposes,
however, both the w(NH) of non hydrogen bonding free
SpyH at 3376 cm−1 and the NHb stretching frequency
of 3287 cm−1 in 3 are arbitrarily used as references to
calculate the difference (Dw) and to estimate an approx-
imate bond energy using Iogansen’s equation [17].
(3)
When crude IrH3(CO)(PPh3)2 was treated with HBF4
in the presence of an excess of HSpy in CDCl3, the
suspension became clear yellow in about 10 min and a
1:1 mixture of two species was formed according to the
1H-NMR spectrum. The products are proposed to be
two dihydrido species [IrH2(CO)(h1-SpyH)(PPh3)2]-
(BF4) and IrH2(CO)(h1-Spy)(PPh3)2 (Eq. (4)) based on
the observation of one NH proton resonance (10.8
ppm) with two sets of hydride resonances of triplet of
doublets: set 1: −7.28 (JPH=17.5, JHH=4.56 Hz) and
−18.5 ppm (JPH=14.04, JHH=4.68 Hz) and set 2:
−8.78 (JPH=17.6, JHH=2.7 Hz) and −13.9 ppm
(JPH=13.4, JHH=2.6 Hz). The former is a monoca-
tionic species containing a monodentate SpyH ligand
cis to one of the hydrides while the latter is a neutral
species with a monodentate pyridinethiolate. These
complexes, however, could not be isolated as they
decomposed in less than 10 min to give several uniden-
tifiable species.
2.6. X-ray structural analyses for 1, 2 and 3
The summary of crystal data parameters is found in
Table 2. Selected bond distances and angles for 1, 2 and
3 are shown in Table 3. The ORTEP diagrams of the
cations for 1, 2 and 3 are shown in Figs. 5, 6 and 8,
respectively.
Complex 1 is a cationic octahedral complex with
(4)
three triphenylphosphine ligands,
a
monodentate
pyridinethione ligand and two hydrides trans to a phos-
phine and a sulfur atom (Fig. 5). It has a mirror plane
in the equatorial plane through atoms of the
pyridinethione, the two hydrides and a phosphorus and
one of its phenyl rings. Therefore half of the total
atoms are assigned by symmetry relationship. The two
hydrogens on the two nitrogens and the two cis-hy-
drides are well-defined in an electron difference map.
One of these species crystallized from chloroform
solution by slow evaporation in the air over several
weeks. The yellowish orange crystals were collected
and analyzed by X-ray diffraction and infrared
spectroscopy. They contain a dicationic monohydrido
complex formulated as [IrH(CO)(h1-SpyH)2(PPh3)2]-
(BF4)2 (3) with two monodentate SpyH ligands, one of
which is cis to the hydride and the other, cis to the
carbonyl.
,
One of the hydrides located at 1.81(8) A from the
iridium atom is in proximity to the NH proton at a

S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
115
Table 2
Summary of crystal data, details of intensity collection, and least-squares refinement parameters for complexes 1, 2 and 3
Complex
1
2
3
Empirical formula
Crystal size (mm)
Formula weight
Crystal class
C61H54BCl6F4IrNP3S
0.42×0.38×0.44
1417.73
Monoclinic
P21/m
C
56.50H54BF4IrN2P2S2
C48H43B2Cl2F8IrN2OP2S2
0.10×0.10×0.10
1226.63
Monoclinic
P21/c
0.63×4.5×3.1
1166.09
Monoclinic
C2/c
Space group
Unit cell dimensions
,
a (A)
10.570(2)
22.964(5)
12.751(2)
102.199(12)
3025.3(10)
2
1.556
2.638
37.528(4)
15.280(2)
23.387(3)
125.046(7)
10979(2)
8
1.411
2.617
4696
18.5325(1)
15.3441(2)
18.4464(2)
94.221(1)
5231.27(9)
4
1.557
2.861
2432
,
b (A)
,
c (A)
i (°)
V (A )
3
,
Z
Dcalc (mg m−3
)
v(Mo–Ka) mm−1
F(000)
1416
T (K)
173(2)
213(2)
296(2)
Reflections collected
Independent reflections
Refinement method
7034
11 983
40 443
9104 (Rint=0.0443)
6686 (Rint=0.0696)
11 790 (Rint=0.0465)
Full-matrix least-squares on
Full-matrix least-squares on F2 Full-matrix least-squares on F2
F2
Data/restraints/parameters
Goodness-of-fit on F2
R1 [I\2|(I)]
6295/2/384
1.109
0.0594
11782/2/531
0.911
0.0461
9104/3/625
1.079
0.0392
wR2 (all data)
0.1677
0.1307
0.1099
Largest difference. peak and hole (e
1.663 and −1.537
1.202 and −0.787
1.013 and −0.725
−3
,
A
)
,
distance of about 2.1 A. The two hydrides cause a
lengthening of the trans MꢀL distances: IrꢀS1 {2.469(3)
Table 3
,
,
A} and IrꢀP2 {2.414(3) A}. Other structural features are
compared with related structures later in this discussion.
Complex 2 is a structural analog to 5. It is a monoca-
tionic iridium (III) complex containing two trans
triphenylphosphine ligands and two monodentate
pyridinethione ligands coordinated via sulfur atoms
trans to two hydrides (Fig. 6). Two hydrides are located
,
Selected bond distances (A) and angles (°) for 1, 2, and 3
Bond length
1
IrꢀS1
IrꢀP2
IrꢀP1
Bond angles
2.469(3)
2.414(3)
2.329(2)
1.81(8)
2.1(2)
P1ꢀIrꢀP2
P1ꢀIrꢀS1
P1ꢀIrꢀH1
P1ꢀIrꢀH2
P2ꢀIrꢀS1
99.10(5)
91.30(5)
80.54(6)
88.6(7)
IrꢀH1 (IrꢀH2)
H1···H(N2)
,
in the difference map at about 1.52 A from the iridium
97.8(1)
atom. From the two elongated IrꢀS distances {2.438(2),
2
,
2.447(2) A}, the trans influence of the hydrides is
IrꢀP1
IrꢀP2
IrꢀS1
IrꢀS2
IrꢀH1 (IrꢀH2)
H(1Ir)···H(1A)
H(2Ir)···H(2B)
2.316(2)
2.315(2)
2.438(2)
2.447(2)
1.52
P1ꢀIrꢀP2
P1ꢀIrꢀS1
P1ꢀIrꢀS2
P2ꢀIrꢀS1
P2ꢀIrꢀS2
S1ꢀIrꢀS2
171.08(6)
89.38(6)
95.83(6)
98.68(6)
89.36(6)
79.98(5)
evident. The NH···HIr distances are found to be 2.0–2.2
,
,
A: a shorter distance (ca. 2.0 A) in the H(2B)···H(2Ir)
,
unit and
a longer distance (ca. 2.2 A) in the
H(1A)···H(1Ir) unit.
2.24
2.03
The fluorines of the counterion BF−4 of 2 are also
weakly associated by hydrogen bonding to the NH units
3
,
at about 2.4 A. Both the NH units are involved in such
IrꢀP2
IrꢀP1
IrꢀS1
IrꢀS2
IrꢀC77
C77ꢀO77
IrꢀH1
H1···N1
H1···H1A(N1)
2.388(1)
2.387(1)
2.409(1)
2.478(1)
1.919(7)
1.136(7)
1.58(4)
2.42
P1ꢀIrꢀP2
P1ꢀIrꢀS1
P1ꢀIrꢀS2
P2ꢀIrꢀS1
P2ꢀIrꢀS2
S1ꢀIrꢀS2
S1ꢀIrꢀC77
S2ꢀIrꢀC77
P1ꢀIrꢀC77
P2ꢀIrꢀC77
IrꢀC77ꢀO77
174.81(4)
85.42(4)
95.53(4)
92.62(4)
88.75(4)
78.14(4)
171.5(2)
110.3(2)
93.0(2)
intermolecular NH···FBF3 hydrogen bonds to make a
polymeric chain (Fig. 7). Note that the counterion BF4−
of the PCy3 analog 5 is observed to be farther away
from the two NH units of the SpyH rings. As noted
earlier, BF−4 in 4 has been observed to form a hydrogen
bond with an NH unit of a coordinated pyridinethione
2.1
,
with a d(F···H) of ca. 2.0 A [3].
Complex 3 is a dicationic octahedral complex with an
88.2(2)
171.6(6)
iridium(III) centre surrounded by two triphenylphos-

116
S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
,
,
{2.409(1) A}. The hydride was located at 1.58(4) A from
the iridium atom. This places the hydride within about
,
2.1 A of the NH proton of the cis SpyH ligand
,
(IrH···N1 distance is about 2.62 A). The SpyH ligand cis
to the hydride is approximately in the equatorial coordi-
nation plane with a dihedral angle of 16.9° about the
C6ꢀS1 bond with respect to the plane consisting of Ir,
H1, S1, S2, and C77. The pyridine unit of the other
SpyH ligand cis to CO is much farther away from the
coordination plane. The dihedral angle of this ring with
respect to the plane is about 31.8° (Fig. 9). The cis
S1ꢀIrꢀS2 angle {78.14(5)°} in 3 is not much different
from those {80.88(6), 79.13(4)°} for 5 and 2, respec-
tively. Unusually wide angles of 128.3(5)° for S1ꢀC6ꢀN1
and 126.4(4)° for S2ꢀC16ꢀN11 are found. These are
shown in Fig. 9 and compared with others in Table 4.
Similar to complex 2, 3 appears to have a weak
F···HꢀN hydrogen bond between one of the BF−4 coun-
terions and one of the SpyH ligands. The NH···F
Fig. 5. ORTEP diagram of the cation of [IrH2(h1-SpyH)(PPh3)3](BF4)
(1) at 173 K.
,
distance in the (N11)H···F2(B) unit is roughly 2.6 A
which is slightly less than the sum of the van der Waals
,
radii of the two atoms in contact (H, 1.2 and F, 1.47 A).
2.7. Comparison of the solid state structures containing
SpyH···HIr bonds
The angles and the bond distances around the coordi-
nated SpyH ligands of six iridium(III) complexes char-
acterized by X-ray analyses are listed in Table 4. All are
Fig. 6. ORTEP diagram of the cation of [IrH2(h1-SpyH)2(PPh3)2](BF4)
(2) (213 K).
Fig. 8. ORTEP diagram of the cation of [IrH(CO)(h1-SpyH)2(PPh3)2]-
(BF4)2 (3) at 296 K.
Fig. 7. Structure of 2 showing a hydrogen bonded polymeric chain
with BF−4 counterions.
phine ligands and two SpyH ligands cis to a hydride and
a carbonyl ligand. The ORTEP diagram for 3 is shown in
Fig. 8. Due to the presence of the trans-hydride, the
,
IrꢀS2 distance is longer {2.478(1) A} than that for IrꢀS1
Fig. 9. Angles in the SpyH ligands of 3.

S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
117
Table 4
Selected angles and bond distances around the SpyH ligands a
1
2
3
4
5
6
a
b
c
d
e
117.4(4)
122.7(9)
2.469(3)(H)
1.70(1)
113.7(2)
122.3(5)
2.438(2)(H)
1.702(6)
3.62(1)
112.4(2)
128.3(5)
2.409(1)(CO)
1.698(6)
3.67(1)
114.4(3)
122.7(6)
2.394(2)(P)
1.730(8)
3.61(1)
111.7(3)
120.4(6)
2.451(2)(H)
1.707(7)
3.49(1)
113.1(2)
122.5(5)
2.355(2)(S)
1.714(6)
3.52(1)
b
3.72(1)
a
b
113.1(2)
121.8(5)
2.447(2)(H)
1.696(7)
3.56(1)
114.6(2) c
126.4(4) c
113.5(2)
121.4(5)
2.434(2)(H)
1.718(8)
3.55(1)
112.2(3)
123.4(6)
2.351(2)(S)
1.705(8)
3.50(1)
c
c b
d
2.478(1)(H)
1.721(5) c
3.91(1) c
e
a
,
Angles a, b in degrees and distances c, d in A. See Fig. 10 for the definition of these angles. Data are listed for two such ligands in 5, 6, 2,
and 3.
b Atoms in brackets are trans atoms. Complexes 6 and 4 also have IrꢀS distances (trans to hydride) in the chelating Spy ligand of 2.486(2) and
,
2.535(2) A, respectively.
c Ligand cis to CO that is not involved in protonꢀhydride bonding.
cationic species containing one or two SpyH ligands.
These include two of the PCy3 complexes (5, 6) and four
of the PPh3 complexes (1–4) (Fig. 1). The angles, IrꢀSꢀC
and SꢀCꢀN are labeled as a and b, respectively, and the
distances, IrꢀS and SꢀC as c and d, respectively. The di-
mensions of the pyridine rings were not found to vary
significantly but are consistent with pyridinethione-like
character.
The sulfur angles a of monodentate SpyH ligands are
in the range of 111 to 114° with an exception of 117.4(4)°
for 1. The carbon angles b in the range of 120 to 123° are
similar to that {120.5(1)°} for free pyridinethione except
for 3 {126.4(4) and 128.3(5)°}. One can expect that, the
smaller the angles a and b in the plane of the IrꢀH, the
closer the NH unit can approach to the iridium hydride.
The larger angles a or b in 1 and 3 are consistent with the
longer NH···HIr distance.
The SꢀC distances d are found in the range from 1.696
,
,
to 1.730 A which are comparable to that {1.698(2) A}
for the free pyridinethione dimer [18]. These are slightly
,
shorter than those {1.724(7) and 1.741(7) A} for the
chelating h2-pyridinethiolate ligands in 6 and 4, respec-
tively.
Table 5 shows a comparison of the selected angles and
distances in the IrꢀH···HꢀN units. The range of
IrꢀH···H(N) angles A (Fig. 12) is roughly 107–125° and
the range of (Ir)H···HꢀN angles B is 135–156°. It should
be noted that the NH is not directed toward the middle
of the MꢀH bond as it is in the structure of the
ReH5(PPh3).3indole as determined by single crystal neu-
tron diffraction [19]. The H···H distances are roughly in
,
the range from 1.9 to 2.2 A. The shortest H···H distance
,
of 1.9 A is in complex 6 which has the shortest Ir···N dis-
tances among the complexes given in Table 5.
Complexes 1 and 2 are related by replacing a PPh3 lig-
and with a protonꢀhydride bonded SpyH ligand (Fig. 1).
In both complexes, the SpyH ligands have
pyridinethione character and the IrꢀS distances show ev-
idence of a trans hydride influence. The N···Ir distances
in 2 are significantly shorter than that in 1 (Table
The N···Ir distances e which are more reliable than the
H···H distances may be a useful indicator of the latter
,
distances. The distances range from 3.49 to 3.61 A with
,
the exceptions of complexes 1 (3.72 A) and 3 (3.67 and
,
,
3.91 A). The longer N···Ir distance of 3.91 A is for the ni-
trogen on the non-interacting SpyH ring cis to the car-
bonyl ligand in 3. In comparison of N···Ir distances
,
,
{3.49(1), 3.55(1) A} for 5 with those {3.62(1), 3.56(1) A}
,
for 2, a slightly longer distance of ca. 0.13 A is found for
one of the SpyH rings in 2.
In the structural series in Table 4, many of the sulfur
atoms are trans to hydrides (X=H in Fig. 10) and the
SꢀIr distances are subject to their trans influence. The
Fig. 10. Definition of the distances and angles listed in Table 4.
,
SꢀIr distances in the influence are 2.44–2.54 A, longer
,
than the normal SꢀIr distances of 2.35–2.40 A. However
these variations in distance do not correlate with the
N···Ir distances e. Shorter SꢀC distance d resulting from
the SpyH ring having pyridinethione rather than proto-
nated pyridinethiolate character (Fig. 11) do not appar-
ently result in shorter N···Ir distances e.
Fig. 11. Three resonance structures of protonated pyridinethiolate
and pyridinethione.

118
S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
Table 5
Comparison of the selected angles and distances in IrꢀH···HꢀN units a
,
,
,
,
Complex d(Ir···N) (A)
d(IrꢀH) (A) d(NꢀH) (A)
dHH (A) A (°)
B (°)
Interacting unit
6
4
1
2
3
3.50(1) 3.52(1) 1.61(3)
0.78(7) 0.70(6)
0.94(8)
0.88
0.87 0.87
0.86
1.9 1.9
2.1(1)
2.1(2)
2.0 2.2
2.1
108 119
112
107
109 114
125
144 145 N(32)ꢀH(32A)···HꢀIr N(22)ꢀH(22A)..HꢀIr
3.61(1)
3.72(1)
1.7(1)
1.81(8)
142
156
N(2)ꢀH(2A)···HꢀIr
N(2)ꢀH(2A)···HꢀIr
3.56(1) 3.62(1) 1.52
3.67(1) 1.58(4)
149 154 N(1)ꢀH(1A)···H(1)ꢀIr N(2)ꢀH(2B)···H(2)ꢀIr
135 N(1)ꢀH(1)···HꢀIr
a See Fig. 12 for the definition of angles A and B.
4). The (PPh3)3 donor set in 1 makes the hydride less
hydridic and therefore a weaker hydrogen-bond accep-
tor than the (PPh3)2(SpyH) donor set in 2. Both the
larger IrꢀSꢀC angle a of 117.4(4)° and the longer N···Ir
examined by T1min measurements. The H···H distances
,
calculated from T1min are in the range from 1.7 to 1.8 A
for the PCy3 and PPh3 complexes. Table 7 also includes
the differences of the NH stretching frequencies in
comparison with that of non-hydrogen bonding SpyH
as well as with that of the SpyH unit (NHb) in 3 that is
weakly hydrogen-bonded to the BF−4 counterion. The
differences (Dw) vary from 265 to 129 cm−1 in compari-
son with the former and from 176 to 40 cm−1 in
comparison with the latter. If we apply Iogansen’s
equation to estimate approximate energy changes using
the Dw values, the strength of the protonꢀhydride bond
can be from 5 to 3 kcal mol−1 with respect to the
w(NH) of free SpyH and 4–1 kcal mol−1 with respect
to the w(NHb) of complex 3. These results again indi-
cate that protonꢀhydride bonds are stronger in com-
plexes with PCy3 than with PPh3 donor ligands.
Fig. 13 shows the relative strength of proton hydride
bonds and NꢀH covalent bonds on an IR scale in
comparison with those between the two extreme cases
(pyridinethione dimer and dilute SpyH). It shows that
the NꢀH···HꢀIr proton hydride bonds in PCy3 and
PPh3 complexes are attractive. The proton hydride
bonds in PCy3 complexes are slightly stronger than
those in PPh3 complexes, but weaker than the conven-
tional NꢀH···S hydrogen bond in the pyridinethione
dimer.
,
distance (ca. 3.72 A) in 1 reflect this weaker NH···HIr
interaction. The IrꢀSꢀC bond angle a is flexible and can
close down from 117 in 1 to 113° in 2 while all the
other angles in the IrSCNH···H ring remain constant.
The flexibility of the IrꢀSꢀC angle is due in part to the
ease of change of CꢀS bond character from thione to
thiolate (Fig. 11).
Complexes 2 and 3 are related by replacing a hydride
ligand with a carbonyl ligand (Fig. 1). There are sub-
stantial differences at the angle b which reflect the
significant differences in the N···Ir distances between 2
and 3. The large angles b {126.4(4), 128.3(5)°} in 3 are
very unusual for an sp2 carbon. It is not clear why the
carbon angles b in 3 are out of the range of all others
of the series in Table 4.
Based on the N···Ir distances, the relative strength of
the proton hydride bonds may be roughly arranged as
shown in the first row of Table 6. Table 6 also lists the
donor ligands that may affect the strength of proton
hydride bonds. The stronger proton hydride bonds
occur when the co-donor ligands are the more basic
PCy3 ligands, while weaker proton hydride bonds occur
when they are the less basic PPh3. The hydricity of the
hydride that is two bonds away from the substituent
change will be affected more by this change than the
acidity of the NꢀH group that is remote from this
change in electronics. Furthermore, in the series, the
weakest bonds are observed when a complex has three
PPh3 or two PPh3 with a CO. Clearly an S2P2 donor set
makes the hydride a better acceptor than the SP3 donor
set.
3. Conclusions
Three new iridium hydride complexes containing pro-
tonꢀhydride bonds are identified in this work. The
NH···HIr distances in these complexes are ca. 2.0–2.1
1
,
,
A by X-ray diffraction and 1.7–1.8 A by H-NMR.
2.8. Comparison of spectroscopic features of proton
hydride bonds
The best indicators of H···H bond strength are the Dw
Table 7 summarizes some important NMR and IR
features for the proton hydride bonds in the SpyH
complexes prepared in this study. Two PCy3 complexes
5 and 6 and three PPh3 complexes 1, 2 and 4 are
Fig. 12. Definition of the angles listed in Table 5.

S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
119
Table 6
Comparison of the N···Ir distances versus co-donor ligands
a
Complexes
5:
6\
2\
4\
3\
1
,
N···Ir (A)
3.49(1) 3.55(1)
S
PCy3
PCy3
H
3.50(1) 3.52(1)
S
PCy3
S
N
S
3.56(1) 3.62(1)
S
PPh3
PPh3
H
3.61(1)
S
PPh3
PPh3
N
3.67(1)
S
PPh3
PPh3
CO
S
3.72(1)
PPh3
PPh3
PPh3
H
Trans to H
Cis to H
Cis to H
Cis to H
Cis to H
S
S
S
S
a N···Ir distances are increasing in the order from complex 5 to complex 1
Table 7
T1min from 1H-NMR and IR bands for IrH and NH groups a,b
c
,
Compound
T1min (IrH)
T1min (NH)
d (H···H) (A)
d (Ir···N)
1
2
4
5
6
0.18 0.23 d
0.20
0.27
0.17
0.17
0.22
0.16
0.24
0.18
0.22
1.890.05
1.890.05
1.890.05
1.790.05
1.790.05
3.72(1)
3.56(1) 3.62(1)
3.61(1)
3.49(1) 3.55(1)
3.50(1) 3.52(1)
e
f
w(IrH) (cm−1
)
w(NH) (cm−1
)
Dw (cm−1
)
Dw (cm−1
)
d(Ir···N)
SpyH g
1
3
4
3376 h
3225
2063, 2197
2180, 2216
2214
151
62
3.72(1)
3247 3287 i
3236
129 89
140
40 0
51
3.67(1) 3.91(1)
3.61(1)
5
6
2137, 2120
2193
3111 3184
3124
265 192
252
176 103
163
3.49(1) 3.55(1)
3.50(1) 3.52(1)
SpyH (dimer)
2900
476
a Proton NMR and T1min (s) measured in CD2Cl2 at 400 MHz.
b IR spectra measured in Nujol using KBr unless otherwise stated.
c H···H distances are estimated as discussed earlier.
d Values are for the hydride not associated with the protonꢀhydride bond.
e Reduction of w from w(NH) of free SpyH of 3376 cm−1
f Reduction of w from w(NHb) at 3287 cm−1 in 3.
.
g Dilute solution of SpyH in CCl4, regarded as non-hydrogen bonding species [16].
h w(NH) of free SpyH.
i w(NHb) not involved in protonꢀhydride bonding.
values from IR and the N···Ir distance from the X-ray
structures. The new dihydride [IrH2(h1-SpyH)-
(PPh3)3](BF4) 1 has the weakest IrH···HN interaction of
six comparable complexes because it is the most con-
gested and it has less basic ligands. Complex 1 provides
a route to [IrH2(h1-SpyH)2(PR3)2](BF4) (2) (R=Ph)
which is usefully compared with the tricyclohexylphos-
phine analog (5) (R=Cy). The less basic PPh3 ligands
of 2 result in less hydridic hydrides and therefore
weaker IrH···HN bonds than in 5 that has the strongest
such bonds of the series. Complex 2 slowly eliminates a
dihydrogen molecule to form the known complex
[IrH(h1-SpyH)(h2-Spy)(PPh3)2](BF4) (4) under mild
conditions. The complex [IrH(CO)(h1-SpyH)2(PPh3)2]-
(BF4)2 (3) contains both a protonꢀhydride bonded
SpyH ligand and a SpyH ligand that is weakly hydro-
gen-bonded to a BF−4 . Like 1, the NH···HIr bond in 3
is weak because of the presence of the electron-with-
drawing carbonyl ligand.
Fig. 13. Comparison of the NH stretching frequencies of coordinated
and free SpyH.

120
S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
4. Experimental
4.1. General procedures
solved by the Patterson method and other non-hydro-
gen atoms were located by successive difference Fourier
syntheses. Non-hydrogen atoms were refined anisotrop-
ically by full-matrix least-squares on F2. Hydrogen
atoms were positioned on geometric grounds (CꢀH 0.96
All preparations were carried out under an atmo-
sphere of dry argon using conventional Schlenk tech-
niques. All the solvents were distilled under argon over
appropriate drying agents prior to use. Tetrahydro-
furan (THF) and diethyl ether (Et2O) were dried over
and distilled from sodium benzophenone ketyl.
Methanol was dried over sodium methoxide. Dichloro-
methane and chloroform were distilled from calcium
hydride. Deuterated solvents were dried over Linde
,
A). All calculations were done and diagrams created
using SHELXTL PC on a Pentium-75 personal computer.
The crystal for 3 belongs to monoclinic space group
,
P21/c with unit cell a=18.5325(1), b=15.3441(2) A
,
with i=94.221(1)°, and c=18.4464(2) A. The struc-
ture was solved by direct methods, completed by subse-
quent Fourier synthesis, and refined by full-matrix
least-squares procedures. The two counterions, and
chloroform solvent molecule were located. All
boronꢀfluorine interatomic separations were restrained
to be equal. All other non-hydrogen atoms were refined
with anisotropic displacement coefficients. The hydride
H1 was located from a difference map and refined with
a riding model.
,
type 4 A molecular sieves and degassed prior to use.
Distilled water was degassed prior to use. Triphenyl-
phosphine, pyridine-2-thione, sodium hydroxide and an
85% solution of HBF4. Et2O complex were purchased
from Aldrich Chemical Company Inc. Iridium trichlo-
ride hydrate was obtained from Johnson–Matthey Co.
Sodium ethoxide was generated in the reaction of
sodium metal with water-free ethanol under argon and
dried to a white powder before use.
Crystal data, data collection, and least squares
parameters are listed in Table 2 and selected bond
distances and angles are in Table 3. Views of cations of
complexes 1, 2 and 3 including the crystallographic
labeling scheme are shown in Figs. 5, 6 and 8,
respectively.
NMR spectra were obtained on a Unity-400, operat-
ing at 400.00 MHz for H, 161.98 MHz for 31P, or on
1
1
a Gemini-300 operating at 300.00 MHz for H, 121.45
MHz for 31P. All 31P-NMR spectra were obtained with
proton decoupling unless otherwise stated. 31P-NMR
chemical shifts were measured relative to H3PO4 as
4.3. Preparation of [IrH2(p1-SpyH)(PPh3)3](BF4) (1)
4.3.1. Method 1
1
internal reference. H-NMR chemical shifts were mea-
sured relative to deuterated solvent peaks or te-
tramethylsilane. Variable temperature T1 measurements
were made at 400 MHz using the inversion recovery
method. Microanalysis was performed by Guelph
Chemical Laboratories Ltd., Ontario.
4.3.1.1. Reaction of fac-IrH3(PPh3)3 with HSpy and
HBF4. fac-IrH3(PPh3)3 (1 g, 1.0 mmol) and HSpy (113
mg, 1.0 mmol) were suspended in CHCl3 (15 ml) in a
Schlenk flask under argon. To this was added excess
HBF4 (500 ml in ether solution). The solution became
clear yellow in a few min. After 10 min the clear
solution was filtered through Celite. The solvent was
then removed in vacuo. The resulting residue was
washed with ether several times (10 ml×3) to give a
bright yellow powder. This was further dried in vacuo.
Yield: 1.1 g, 91%.
4.2. Crystallographic structural determination
Complexes 1, 2 and 3 were crystallized by the slow
evaporation of a chloroform solution at r.t. A single
crystal for 1, 2 and 3 suitable for X-ray analysis was
mounted with epoxy glue and analyzed at 173 (1), 213
(2) and 296 K (3). The crystalline system for 1 was
found to be monoclinic with space group P21/m. The
unit cell dimensions of the crystal are a=10.570(2),
4.3.2. Method 2
,
b=22.964(5)
A
with i=102.199(12)°, and c=
4.3.2.1. Reaction of IrH3(PPh3)3 (fac- and mer- mixture)
with HSpy and HBF4. A mixture of fac- and mer-
IrH3(PPh3)3 (1 g, 1.0 mmol) and HSpy (113 mg, 1.0
mmol) were suspended in CH2Cl2 (15 ml) under argon.
To this was added excess HBF4 (500 ml in ether solu-
tion). The work up was similar to that of Section 4.3.1
with similar yield: Anal. Calc. for C59H52BF4IrNP3S.
CHCl3: C, 55.5; H, 4.12; N, 1.08. Found: C, 55.72; H,
4.35; N, 1.06%. NMR (CDCl3, l). 31P{1H}: 2.23 (d,
,
12.751(2) A. The crystal for 2 has the monoclinic space
,
group C2/c with unit cell a=37.528(4), b=15.280(2) A
with i=125.046(7)°, and c=23.387(3) A. Intensity
data for 1 and 2 were collected on a Siemens P4
diffractometer, using graphite monochromated Mo–Ka
,
,
radiation (u=0.71073 A). The ꢀ scan technique was
applied with variable scan speeds. Intensities of three
standards measured for each compound every 97 reflec-
tions showed no decay. Data were corrected for
Lorentz, and polarization effects and for absorption.
The Ir atom position in the structure of 1 and 2 was
1
J=15.2 Hz), −0.93 (t, J=15.6 Hz); H: −12.7 (dtd,
JtPH=116, JcPH=22, JHH=3.6 Hz, 1H, IrꢀH), −15.75
(qd, JHH=3.6, 1H, IrꢀH), 6.4–7.8 {m, 49 H, overlap-

S.H. Park et al. / Journal of Organometallic Chemistry 609 (2000) 110–122
121
ping P(C6H5)3 with SC5H4NH+}, 10.9 {br s, 1H,
(SC5H4NH+)}. IR (KBr pellet): w(IrꢀH), 2063, 2197
4.6. Crystallization of
[IrH(CO)(p1-SpyH)2(PPh3)2](BF4)2 (3)
cm−1; w(NH), 3225 cm−1
.
In a Schlenk flask crude IrH3(CO)(PPh3)2 (50 mg,
0.07 mmol) and HSpy (18 mg, 0.16 mol) were dissolved
in CHCl3 (2 ml). To this was added an excess of HBF4
etherate and allowed to react for 10 min during which
time gas evolution occurred and the solution became
clear yellow. This was left for slow evaporation at r.t. in
air for about a week resulting in some orange–yellow
crystals deposited among a yellow powder. The crystals
were collected and used for X-ray analysis and infrared
studies. IR (KBr, Nujol): w(CO), 2044 cm−1 (s); w(IrH),
2180, 2216 cm−1 (m); w(NH), 3247 (w, br), 3287 cm−1
(w).
4.4. Formation of [IrH2(p1-SpyH)2(PPh3)2](BF4) (2)
[IrH2(h1-SpyH) (PPh3)3](BF4) (1) (100 mg, 0.085
mmol) and HSpy (53 mg, 0.477 mmol) dissolved in
CHCl3 (6 ml) were added to a Schlenk flask fitted with
a magnetic stirring bar under argon. This was stirred
for over a week at r.t. The solution was monitored by
31P{1H}-NMR. There was a major species with a reso-
nance at 9.4 ppm (s) and a minor species at −9.97 ppm
(s) in addition to unreacted 1. The solution was further
stirred for a second week and checked by 31P{1H}-
NMR; no more unreacted 1 was observed. All the
volatiles were then removed in vacuo. To the residue
was added ether (10 ml) to wash out excess HSpy and
to give a light yellow powder. Three species were ob-
served by 31P{1H}-NMR: the major species was
[IrH2(h1-SpyH)2(PPh3)2](BF4) (2) and the minor species
are trans-[IrH(h1-SpyH)(h2-Spy)(PPh3)2](BF4) (4%) and
cis-[IrH(h1-SpyH)(h2-Spy)(PPh3)2](BF4) (4). The inten-
sities of the minor resonances grow over time as the
intensity of the resonances for the major species de-
creases. The final spectrum is consistent with that for
cis-[IrH(h1-SpyH)(h2-Spy)(PPh3)2](BF4) (4) [3]. Selected
proton NMR resonances (l): NH: 11.74 (br s, 2); 11.91
(br s, 4%); 11.86 (br s, 4). IrH: −16.10 (t, JPH=15.3 Hz,
5. Supplementary material
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data
Centre, CCDC nos. 140155 (1), 140156 (2), 140093 (3).
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
2); −16.68 (t, JPH=12.21 Hz, 4%); −17.78 (dd, JPH
14.3 Hz, 4).
=
Acknowledgements
NSERC Canada is thanked for an operating grant to
RHM.
4.5. Preparation of crude IrH3(CO)(PPh3)2
IrHCl2(PPh3)3 [20] (500 mg, 0.476 mmol) was sus-
pended in THF (25 ml) in a Schlenk flask fitted with a
stirring bar under dihydrogen gas. To this was added
ground sodium hydroxide (1 g, 0.025 mol). The suspen-
sion was stirred for about 20 h at r.t. followed by
evaporation of the solvent. To the residue was added
degassed water (ca. 20 ml). This was stirred for 10 min
before filtration. The wet residue was stirred in
methanol (ca. 20 ml) for 10 min. This was followed by
a vacuum filtration and drying to obtain a pale grey
yellow powder. This was washed with ether (2×10 ml)
and dried in vacuo. Yield: 280 mg, 78% based on
IrH3(CO)(PPh3)2 [15]. NMR (CDCl3, l) for the major
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