A new methodology for the preparation of cationic organoplatinum(II) complexes with hydrogen-bonding functionality

Article abstract of DOI:10.1021/om010127c

A new methodology for the preparation of two series of cationic organoplatinum(II) complexes with hydrogen-bonding functionality is described. The mononuclear complexes of the type trans-[Pt(σ-aryl)L(PPh₃)₂]OTf (L = nicotinic acid, a

Full text of DOI:10.1021/om010127c

Organometallics 2001, 20, 3373-3382
3373
Articles
A New Meth od ology for th e P r ep a r a tion of Ca tion ic
Or ga n op la tin u m (II) Com p lexes w ith Hyd r ogen -Bon d in g
F u n ction a lity
David P. Gallasch, Edward R. T. Tiekink, and Louis M. Rendina*
Department of Chemistry, The University of Adelaide, Adelaide,
South Australia 5005, Australia
Received February 16, 2001
A new methodology for the preparation of two series of cationic organoplatinum(II)
complexes with hydrogen-bonding functionality is described. The mononuclear complexes
of the type trans-[Pt(σ-aryl)L(PPh3)2]OTf (L ) nicotinic acid, aryl ) C3-benzoic acid (9) or
C4-benzoic acid (10); L ) isonicotinic acid, aryl ) C3-benzoic acid (11) or C4-benzoic acid
(12); OTf ) trifluoromethanesulfonate (triflate)) constitute the first series, and the dinuclear
complexes of the type trans-[Pt(σ-aryl)(PPh3)2(µ-L)Pt(σ-aryl)(PPh3)2](OTf)2 (L ) 1,1-bis(4-
pyridyl)ethene, aryl ) C3-benzoic acid (19) or C4-benzoic acid (20); L ) 4,7-phenanthroline,
aryl ) C3-benzoic acid (21) or C4-benzoic acid (22); L ) 4,4′-bipyridine, aryl ) C3-benzoic
acid (23) or C4-benzoic acid (24)) constitute the second series. The methodology described
here involves the protection of the carboxylic acid group of a 3- or 4-iodobenzoic acid precursor
as the tert-butyldiphenylsilyl ester, followed by an oxidative addition reaction of the C-I
bond with the Pt(0) species Pt(PPh3)4 to yield the key (σ-aryl)iodoplatinum(II) intermediates
3 and 4, the structures of which were determined by X-ray crystallography. Subsequent
treatment of these products with AgOTf, followed by the addition of a suitable monodentate
or bridging bidentate N-donor ligand and, finally, facile removal of the silyl protecting group-
(s) with HOTf affords the target complexes with hydrogen-bonding functionality in high
1
yield. Variable-temperature H NMR experiments with the silyl-protected complexes trans-
[Pt(σ-aryl)L(PPh3)2]OTf (aryl ) C3-tert-butyldiphenylsilyl benzoate, L ) nicotinic acid (5) or
isonicotinic acid (7)) confirm that a dynamic intramolecular process involving the pyridyl
ligand is occurring. The rotational barrier of a pyridyl ligand in an organoplatinum(II)
complex is reported for the first time, where ∆Gq ) 48.3 ( 0.9 and 45.7 ( 0.9 kJ mol-1 for
complexes 5 and 7, respectively.
In tr od u ction
means of controlling the self-assembly process, hybrid
molecular polygons are feasible.3,4
Although the coordinate-covalent bond is an efficient
and versatile motif for the construction of molecular
polygons and polyhedra,1 its combination with the
hydrogen bond is an alternative approach for the
assembly of discrete macrocyclic entities containing
transition metal centers. By using coordinate-covalent
bonds to afford tectons2 (building blocks) of appreciable
size and the highly directional hydrogen bond as a
Recently, we have shown that dinuclear organoplati-
num(II) tectons with hydrogen-bonding functionality
can be programmed to self-assemble into dimeric and
trimeric macrocycles in CD2Cl2 solution at 298 K.4a The
synthetic methodology that was employed in the prepa-
ration of the complexes consisted of a well-known double
oxidative addition reaction of an aryl di-iodide to a
platinum(0) species,5 followed by triflate metathesis of
the iodo ligands in the resulting diplatinum(II) product
and, finally, the addition of a N-donor ligand containing
the hydrogen-bonding functionality, e.g., nicotinic acid,
to the diplatinum(II)-triflato species.4 In principle, one
* Corresponding author. Tel: 61 8 8303 4269. Fax: 61 8 8303 4358.
E-mail: lou.rendina@adelaide.edu.au.
(1) For recent reviews, see: (a) Leininger, S.; Olenyuk, B.; Stang,
P. J . Chem. Rev. 2000, 100, 853. (b) Stang, P. J . Chem. Eur. J . 1998,
4, 19. (c) Olenyuk, B.; Fechtenko¨tter, A.; Stang, P. J . J . Chem. Soc.,
Dalton Trans. 1998, 1707. (d) Fujita, M. Chem. Soc. Rev. 1998, 27,
417. (e) J ones, C. J . Chem. Soc. Rev. 1998, 27, 289. (f) Fujita, M.; Ogura,
K. Coord. Chem. Rev. 1996, 148, 249. (g) Stang, P. J .; Olenyuk, B. Acc.
Chem. Res. 1997, 30, 502. (h) Cao, D. H.; Chen, K.; Fan, J .; Manna, J .;
Olenyuk, B.; Whiteford, J . A.; Stang, P. J . Pure Appl. Chem. 1997, 69,
1979.
(3) (a) Metzger, S.; Lippert, B. J . Am. Chem. Soc. 1996, 118, 12467.
(b) Sigel, R. K. O.; Freisinger, E.; Metzger, S.; Lippert, B. J . Am. Chem.
Soc. 1998, 120, 12000.
(4) (a) Gianneschi, N. C.; Tiekink, E. R. T.; Rendina, L. M. J . Am.
Chem. Soc. 2000, 122, 8474. (b) Crisp, M. G.; Pyke, S. M.; Rendina, L.
M. J . Organomet. Chem. 2000, 607, 222.
(2) (a) Ducharme, Y.; Wuest, J . D. J . Org. Chem. 1988, 53, 5787.
(b) Gallant, M.; Viet, M. R. P.; Wuest, J . D. J . Org. Chem. 1991, 56,
2284.
(5) Manna, J .; Kuehl, C. J .; Whiteford, J . A.; Stang, P. J . Organo-
metallics 1997, 16, 1897.
10.1021/om010127c CCC: $20.00 © 2001 American Chemical Society
Publication on Web 07/12/2001

3374 Organometallics, Vol. 20, No. 16, 2001
Gallasch et al.
Sch em e 1
could prepare platinum tectons that are isomeric to
those described previously by employing an aryl iodide
with hydrogen-bonding functionality in the oxidative
addition reaction and by using a suitable N-donor ligand
to bridge the two platinum(II) centers after triflate
metathesis. However, this alternative synthetic method
would present a formidable challenge. Several types of
transition metal complexes in low oxidation states are
known to react with the O-H bond of carboxylic acids,6
and protection of the acidic functional group in the aryl
iodide is a necessary step if the oxidative addition
reaction involving platinum(0) is to proceed cleanly.
A protecting group that is sufficiently robust to
withstand the reaction conditions throughout the syn-
thetic pathway is required. In particular, it must be
chemically stable at the elevated temperatures that are
required for an oxidative addition reaction. Further-
more, the protecting group must be cleaved under mild
conditions so that the integrity of the platinum coordi-
nation sphere is not compromised. Protecting the car-
boxylic acid as a silyl ester promises to satisfy both the
stability and cleavage requirements. Silyl esters are
particularly stable to nonaqueous environments, even
when heated to high temperatures. In addition, they can
be cleaved at room temperature by mildly acidic or basic
hydrolysis or, more commonly, with fluoride salts.7
In this work, the wide applicability of a silyl ester
protection/deprotection methodology will be demon-
strated by the preparation of several types of cationic
organoplatinum(II) complexes with carboxylic acid func-
tionality from a platinum(0) precursor, some of which
are isomeric with those reported previously.4a To the
best of our knowledge, this approach has not been
previously employed for an oxidative addition reaction
in transition metal chemistry.
of an intractable mixture containing several unidenti-
fied products. After numerous attempts at obtaining a
reproducible, high-yielding preparation of the desired
organoplatinum(II) complexes with hydrogen-bonding
functionality, an alternative approach employing the
protection of the carboxylic acid group was investigated.
3- and 4-iodobenzoic acids were protected as the corre-
sponding tert-butyldiphenylsilyl esters 1 and 2, respec-
tively.7 Both products were obtained as colorless, crys-
talline solids in high yield.
P r ep a r a tion of th e Iod op la tin u m (II) Com p lexes
3 a n d 4. The oxidative addition reaction of the aryl
iodide derivatives 1 and 2 with Pt(PPh3)4 successfully
resulted in the formation of the corresponding iodoplati-
num(II) complexes 3 and 4, respectively, in high yield
and purity (Scheme 1). Both products were isolated as
air- and moisture-stable, colorless solids.
1
The H NMR spectrum of 3 shows a broad multiplet
between δ 7.17-7.74 due to the SiPh2 and PPh3 protons,
which obscures the H2 resonance of the σ-aryl group.
The H4 and H6 protons appear as doublets at δ 7.03 and
7.08, respectively, each with three-bond coupling (3J HH
) 7.8 Hz) to the adjacent H5 proton which appears as a
triplet at δ 6.28. 2D-COSY NMR experiments allowed
the H,6 H4, and H5 protons to be assigned unambigu-
ously. The symmetry of 4 simplifies its 1H NMR
spectrum, which shows only a broad multiplet between
δ 7.22-7.72 due to the SiPh2 and PPh3 protons, a
multiplet between δ 6.80-6.88 due to the AA′BB′ spin
system which is present in the σ-aryl ligand, and a
singlet at δ 1.12 due to the CH3 protons.
The 31P{1H} NMR spectra of 3 and 4 display a singlet
resonance that is flanked by 195Pt (I ) 1/2; abundance
) 33.8%) satellite signals for the equivalent trans-PPh3
ligands at δ 22.0 (1J PPt ) 3024 Hz) and δ 21.4 (1J PPt
)
3021 Hz), respectively. The chemical shifts of the
resonances and the magnitude of the Pt-P coupling
constants are comparable to those reported for other
σ-arylplatinum(II) complexes with mutually trans PPh3
ligands.4a,5,8 The 195Pt{1H} NMR spectra of 3 and 4 show
the expected triplet resonances at δ -4732 and -4700,
Resu lts a n d Discu ssion
The direct reaction of 3- or 4-iodobenzoic acid with
Pt(PPh3)4 in toluene solution resulted in the formation
(6) (a) Ladipo, F. T.; Kooti, M.; Merola, J . S. Inorg. Chem. 1993, 32,
1681. (b) Van Doorn, J . A.; Masters, S.; Van der Woude, C. J . Chem.
Soc., Dalton Trans. 1978, 1213. (c) Marder, T. B.; Cham, D. M.-T.;
Fultz, W. C.; Calabrese, J . C.; Milstein., D. J . Chem. Soc., Chem.
Commun. 1987, 1885.
(7) Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic
Synthesis, 2nd ed.; J ohn Wiley & Sons: New York, 1991.
1
respectively, with J PtP within experimental error of
those reported above.
(8) Pregosin, P. S.; Kunz, R. W. 31P and 13C NMR of Transition Metal
Complexes; Springer-Verlag: Berlin, 1979.

Cationic Organoplatinum(II) Complexes
Organometallics, Vol. 20, No. 16, 2001 3375
significant interaction involving the O(2) atom is mani-
fested in the separation of 2.57 Å from a symmetry-
related H(8) atom, symmetry operation: 0.5-x, -y,
0.5+z.
The molecular structure of 4 has also been deter-
mined. Although full details of the structure are not
reported here owing to ambiguity associated with the
solvent of crystallization, the molecular structure of the
complex is unambiguous. Substitution at the 4-position
of the σ-aryl ligand in 4 compared with that in 3 leads
to a more “open” structure. Geometric parameters about
the platinum center are experimentally equivalent to
the comparable parameters in 3, and the relative
disposition of the phenyl rings also mirrors that in 3.
P r ep a r a tion of Mon on u clea r Com p lexes w ith
Hyd r ogen -Bon d in g F u n ction a lity. Treatment of 3
or 4 with 1 equiv of AgOTf led to the formation of the
corresponding triflato complexes in situ. The asym-
metric, mononuclear complexes 5-8, containing one free
and one silyl-protected carboxylic acid group, were
formed by the addition of nicotinic acid or isonicotinic
acid to the solution containing the platinum(II)-triflato
species. Facile removal of the silyl protecting group in
5-8 was effected by the addition of HOTf in CH2Cl2 at
room temperature to afford one series of target com-
plexes 9-12 (Scheme 1), each containing two carboxylic
acid groups that are available for hydrogen-bonding
interactions.
Initially, Bu4NF was used for the deprotection of the
carboxylic acid group in 5-8. Although the silyl group
appeared to be cleaved successfully by this method, the
resulting product was found to be poorly soluble in
common organic solvents, probably due to the fluoride
acting as a counterion in the target cationic complexes
9-12. To maintain the triflate counterion in these
complexes, HOTf was used to hydrolyze the silyl ester.
Interestingly, at no stage was electrophilic cleavage of
the Pt-C bond observed, as reported for other organo-
platinum(II) complexes where the reaction is thought
to proceed by an oxidative addition mechanism involving
protonation of the electron-rich, coordinatively unsatur-
ated metal center to afford a hydridoplatinum(IV)
intermediate.9 The absence of Pt-C bond protonolysis
in any of the complexes prepared in this work is most
probably the result of the cationic nature of the silyl-
protected complexes.
Selected 1H, 31P{1H}, and 195Pt{1H} NMR spectro-
scopic data for the isomeric dicarboxylic acid complexes
9-12 are presented in Table 2. The assignment of the
pyridyl proton resonances was facilitated by 2D-COSY
NMR experiments for 9 and 11, whereby distinct cross-
peaks were observed for all coupled protons of the
pyridyl ring system. For the nicotinic acid complexes 9
and 10, the H2 proton appears as a singlet at ca. δ 8.6
owing to its proximity to the pyridyl nitrogen atom. The
H4 and H6 protons each appear as doublets at ca. δ 7.85
and 8.5, respectively, with three-bond couplings to the
adjacent H5 proton. The H5 proton in complex 9 appears
as a doublet of doublets at ca. δ 6.8, while the H5 proton
in 10 is masked by other aromatic signals. For the
isonicotinic acid complexes 11 and 12, the H2,6 and H3,5
protons appear as characteristic AA′XX′ signals at ca.
δ 8.5 and 7.24, respectively, with cross-peaks to each
F igu r e 1. Molecular structure and atomic numbering
scheme for 3.
Ta ble 1. Selected In ter a tom ic (Å, d eg) P a r a m eter s
for 3
Pt-I
2.7071(8)
2.302(2)
1.679(5)
1.204(9)
94.42(5)
171.5(2)
88.1(2)
Pt-P(1)
Pt-C(1)
C(7)-O(1)
2.309(2)
2.015(6)
1.346(9)
Pt-P(2)
Si-O(1)
C(7)-O(2)
I-Pt-P(1)
I-Pt-C(1)
P(1)-Pt-C(1)
Pt-C(1)-C(2)
I-Pt-P(2)
88.39(5)
166.41(7)
91.0(2)
P(1)-Pt-P(2)
P(2)-Pt-C(1)
Pt-C(1)-C(6)
122.8(5)
118.8(5)
X-r a y Str u ctu r e of Com p lex 3. The molecular
structure of 3 was determined by X-ray crystallographic
methods. The structure is shown in Figure 1, and
selected geometric parameters are collected in Table 1.
The platinum atom exists in the expected square planar
geometry defined by a C, I, P2 donor set. However, there
are significant deviations from the ideal geometry, as
seen in the respective deviations of the C(1), I, P(1), and
P(2) atoms from their weighted least-squares plane of
0.0025(5), -0.042(2), -0.047(2), and 0.667(6) Å; the
platinum atom lies 0.2172(3) Å above this plane. The
aryl group, C(1)-C(6), is orthogonal to the ligand donor
set, forming a dihedral angle of 83.9(2)°. The carboxylate
residue is planar with the C(1)-C(6) ring, as evidenced
by the O(1)/C(7)/C(3)/C(2) torsion angle of 1.7(9)°. Steric
congestion in the structure is apparent from Figure 1,
from which it can also be seen that two phosphorus-
bound phenyl rings on each phosphorus atom are
directed away from the platinum-bound aryl group. The
dihedral angle of 22.9(4)° between C(1)-C(6) and C(24)-
C(29), and 25.0(3)° between C(1)-C(6) and C(42)-C(47),
indicates that there is no evidence for significant π‚‚‚π
interactions between them, even though the respective
distances between the ring centroids are 3.74 and 3.80
Å. The most significant intermolecular interaction in the
lattice is of the type C-H‚‚‚π. The distance between
C(33)-H(31) and the ring centroid of C(36)-C(41) is
2.75 Å, and the angle subtended at H(31) is 148.4°;
symmetry operation: 0.5+x, -0.5-y, -1-z. The most
(9) Rendina, L. M.; Puddephatt, R. J . Chem. Rev. 1997, 97, 1735.

3376 Organometallics, Vol. 20, No. 16, 2001
Gallasch et al.
Ta ble 2. Selected 1H, 31P {1H}, a n d 195P t{1H} NMR Sp ectr oscop ic Da ta for th e Mon on u clea r Com p lexes
9-12a
δ (1H)
complex
H2
H3
H4
7.85
H5
H6
H8
H9
H10
H11
H12
δ (31P)b δ (195Pt)b
-4318
) (2995) (3008)
9
8.58 (s)
c
c
6.96 (dd,
8.51 (d,
d
c
7.04 (d,
6.39 (t, 7.11 (d, 22.6
(d, J HH 3J HH ) 7.8,
3J HH
)
3J HH ) 7.8)
3J HH
7.8)
e
)
3J HH
7.8)
f
3
) 7.8)
3J HH ) 5.4)
5.4)
10
11
8.58 (s)
7.84
d
8.51 (d, 6.90-6.98
c
22.2
(2993) (2990)
-4297
3
(d, J HH
3J HH
5.1)
h
)
(m, AA′BB′)
) 7.5)
c
8.47 (AA′ 7.24 (XX′
portion) portion)
g
g
d
c
6.95 (d,
6.36 (t, 7.10 (d, 22.2
-4309
(2990) (2993)
3J HH ) 7.5)
3J HH
7.5)
e
)
3J HH
7.5)
f
)
12
8.46 (AA′ 7.24 (XX′
portion) portion)
c
h
6.89
(m, AA′BB′)
c
21.9
(2992) (2984)
-4288
a
b 1
Measured in CD3OD; coupling constants in hertz. Quoted multiplicities do not include 195Pt satellites.
J
coupling constants (Hz)
PtP
in parentheses. c Not applicable. Resonance masked by other aromatic signals. e Equivalent to H9. f Equivalent to H8. Equivalent to
d
g
H3. Equivalent to H2.
h
other in the 2D-COSY NMR spectrum. The proton
resonances of the 3-substituted σ-aryl ligand in 9 and
11 were unambiguously assigned with the assistance
of 2D-COSY NMR experiments. The H11 proton appears
as a triplet at ca. δ 6.4, with three-bond couplings to
the H10 and H12 protons, which appear as doublets at
ca. δ 7.0 and 7.1, respectively. All aromatic protons of
the 4-substituted σ-aryl ligand in 10 and 12 appear as
a multiplet due to the AA′BB′ spin system that is
present in the σ-aryl group. The H8,12 and H9,11 protons
of 10 appear as a multiplet between δ 6.90-6.98, and
the corresponding protons of 12 appear as a multiplet
centered at δ 6.89.
The 31P{1H} NMR spectra of 9-12 display a singlet
resonance that is flanked by 195Pt satellite signals at
ca. δ 22 (1J PPt ≈ 3000 Hz). The signal has shifted ca. 1
ppm downfield when compared to the 31P{1H} NMR
spectra of the silyl-protected complexes 5-8. This small
shift is mainly attributed to the change in solvent from
CDCl3 to CD3OD, which was necessary to maintain the
solubility of the complexes.
ligand from the parent platinum(II) species, a feature
that has been reported previously for related com-
plexes.4
Dyn a m ic In t r a m olecu la r R ea r r a n gem en t s of
1
Com p lexes 5 a n d 7. The H NMR spectra of 5 and 7
displayed the H2 and H6 protons as broad peaks at room
temperature. To further investigate this phenomenon,
variable-temperature (VT) 1H NMR spectroscopy ex-
periments were performed with 5 (Figure 2) and 7 in
CD2Cl2 solution.
1
The VT H NMR spectroscopy experiments support
a nondegenerate intramolecular rearrangement be-
tween the syn (5a ) and anti (5b) isomers of complex 5
(Scheme 2). Free rotation about the Pt-C(aryl) bond is
not possible as a consequence of the considerable steric
interactions between the bulky PPh3 ligands and the
3-substituted tert-butyldiphenylsilyl ester group. This
proposal is supported by the X-ray structure of the
precursor complex 3 (Figure 1), which shows that the
silyl group is effectively locked between the mutually
trans PPh3 ligands. Furthermore, the 4-substituted
isomers 6 and 8 do not exhibit related dynamic NMR
behavior, consistent with free rotation about the Pt-
C(aryl) bond in these complexes. The rotation of the
pyridyl ligand about the Pt-N bond in 5 is not signifi-
cantly hindered, however, even though it would possess
partial double-bond character owing to the back-bonding
of the filled metal d-orbitals with appropriate symmetry
into the unoccupied π*-orbitals of the pyridyl ligand.11,12
As a result, both the syn and anti rotamers of 5 are
The 195Pt{1H} NMR spectra of 9-12 show the ex-
pected triplet resonance at ca. δ -4300 and coupling
constants (1J PtP ≈ 3000 Hz). As would be expected,
essentially no shift in the 195Pt signal is observed after
deprotection of the carboxylic acid group. Furthermore,
a considerable downfield shift of ca. 400 ppm is observed
in the 195Pt{1H} NMR spectra upon substituting the less
electronegative iodo ligand with a N-donor ligand.10
The complexes 9-12 were further analyzed by ESI
mass spectrometry in the positive ion mode. Each of the
complexes displayed a peak at m/z 963 attributed to [M
- OTf]+. Furthermore, peaks at m/z 840 and 719 were
also detected, and they are most likely attributed to the
loss of nicotinic acid followed by the loss of the σ-aryl
1
readily observed by H NMR spectroscopy at low tem-
peratures. As the populations of the two rotamers are
almost equal in CD2Cl2 solution, the difference in free
energies for the ground-state molecular structures of 5
(11) Tomasik, P.; Ratajewicz, Z. Pyridine-Metal Complexes; J ohn
Wiley & Sons: New York, 1985; Vol. 14, Part 6B.
(12) Note that the cationic charge of complex 5 is expected to
diminish the degree of back-bonding.
(10) Pregosin, P. S. Coord. Chem. Rev. 1982, 44, 247.

Cationic Organoplatinum(II) Complexes
Organometallics, Vol. 20, No. 16, 2001 3377
num(II) complex has been determined. Its value is
comparable to that determined for the rotation of the
3-picoline ligands about the Pt-N bond in the cationic
coordination complex [Pt(R-(+)-BINAP)(3-picoline)2]-
(OTf)2 (BINAP ) 2,2′-bis(diphenylphosphino)-1,1′-bi-
naphthyl) in CD3OD solution (58.5 ( 2.1 kJ mol-1).16
In the case of the isonicotinic acid derivative 7, a
dynamic process related to 5 was observed by means of
1
VT H NMR spectroscopy experiments in CD2Cl2 solu-
tion. In contrast to 5, however, complex 7 displays
degenerate intramolecular behavior, where the ground-
state free energies of the rotamers are identical. Once
again, a value for ∆Gq can be derived from Tc (238 K) of
the H2,6 protons, and in this case ∆Gq ) 45.7 ( 0.9
238
kJ mol-1
.
Upon cleavage of the silyl ester by treatment of 5 or
7 with HOTf, the σ-aryl ligand is able to rotate freely
about the Pt-C(aryl) bond, and consequently, no broad
aromatic signals are observed in the room-temperature
1H NMR spectra of the deprotected complexes 9 and 11.
This observation further supports the proposed dynamic
intramolecular rearrangement of complexes 5 and 7.
P r ep a r a tion of Din u clea r Com p lexes w ith Hy-
d r ogen -Bon d in g F u n ction a lity. A second series of
organoplatinum(II) complexes was synthesized by the
same methodology as the first series except that a
bridging bidentate N-donor ligand such as 4,4′-bipyri-
dine was added to 2 equiv of the platinum(II)-triflato
species derived from the corresponding iodo complex 3
or 4. Removal of the silyl protecting groups in 13-18
with HOTf yielded the symmetrical, dinuclear organo-
platinum(II) complexes with hydrogen-bonding func-
tionality, 19-24 (Scheme 3).
Selected 1H, 31P{1H}, and 195Pt{1H} NMR spectro-
scopic data for the deprotected species 19, 20, 23, and
24 are presented in Table 3. The broad aromatic signals
that are observed in the room-temperature 1H NMR
spectra of the 4,7-phenanthroline complexes 21 and 22
(and their precursors 15 and 16) are most probably the
result of a dynamic intramolecular process related to
that described earlier for the mononuclear species 5 and
7, the details of which require further investigation. As
expected, the 31P{1H} and 195Pt{1H} NMR spectra of
19-24 are almost identical to those observed for the
corresponding silyl-protected species, and furthermore,
the signals lie in the same chemical shift range as those
of the mononuclear species 9-12.
Complexes 19-24 were analyzed by ESI mass spec-
trometry in the positive ion mode. The base peaks in
the MS of the complexes were observed at m/z 1022,
1020, and 996 for the 1,1-bis(4-pyridyl)ethene, 4,7-
phenanthroline, and 4,4′-bipyridine derivatives, respec-
tively, and each is attributed to the species [M - 2OTf
- [Pt(PPh3)2C6H4(CO2H)]+]+. No evidence was obtained
for an intact, doubly charged species. The facile loss of
the N-donor ligand is probably facilitated by the strong
trans effect of the σ-aryl group.
1
F igu r e 2. VT H NMR spectra of the pyridyl (H2, H,4 H,5
and H6) and σ-aryl (H11) protons of 5 in CD2Cl2 solution.
Sch em e 2
must be negligible in this solvent.13 Furthermore, one
can reasonably assume that the free energies of activa-
tion (∆Gq) for the forward and reverse processes are
almost equal, and a value for ∆Gq can thus be derived
from the coalescence temperature (Tc) by means of a
modified Eyring equation.14 For example, Tc ) 243 K
and ∆Gq
) 48.3 ( 0.9 kJ mol-1 for the H5 and H5′
243
signals.15 To our knowledge, this is the first time the
rotational barrier of a pyridyl ligand in an organoplati-
(13) We were unable to observe any significant increase in the
intensity of one or more of the signals when CD3OD was used as the
solvent.
Con clu sion s
(14) Gu¨nther, H. NMR Spectroscopy: Basic Principles, Concepts, and
Applications in Chemistry, 2nd ed.; J ohn Wiley & Sons: New York,
1995; p 335.
The facile protection and deprotection steps employed
in this work extend the utility of the oxidative addition
(15) Alternatively, ∆Gq for the rotation process can also be calculated
from the Tc (240 K) of resonances H6/H6′and H2/H2′. In both cases,
∆Gq ) 46.1 ( 1.0 kJ mol-1. A more detailed study of this phenom-
(16) Fuss, M.; Siehl, H.-U.; Olenyuk, B.; Stang, P. J . Organometallics
1999, 18, 758.
240
enon based on line shape analysis of the spectra is planned.

3378 Organometallics, Vol. 20, No. 16, 2001
Gallasch et al.
Sch em e 3
Ta ble 3. Selected 1H, 31P {1H}, a n d 195P t{1H} NMR Sp ectr oscop ic Da ta for th e Din u clea r Sp ecies 19, 20, 23,
a n d 24a
δ (1H)
complex
H3,5
H2,6
H8
H9
H10
H11
H12
δ (31P)b
δ (195Pt)b
19
6.38 (XX′
portion)
6.36 (XX′
portion)
6.84 (XX′
portion)
6.83 (XX′
portion)
8.29 (AA′
portion)
8.28 (AA′
portion)
8.39 (AA′
portion)
8.36 (AA′
portion)
c
d
6.96 (d,
3J HH ) 7.5)
d
6.37 (t,
3J HH ) 7.5)
e
7.12 (d,
3J HH ) 7.5)
f
22.4
(3002)
22.1
(3000)
22.2
(2985)
21.9
(2990)
-4310
(2992)
-4288
(3016)
-4310
(3009)
-4288
(2979)
20
23
24
6.90 (m, AA′BB′)
c
d
6.96 (d,
3J HH ) 7.8)
d
6.38 (t,
3J HH ) 7.8)
e
7.11 (d,
3J HH ) 7.8)
f
6.90 (m, AA′BB′)
a
b 1
Measured om CD3OD; coupling constants in hertz. Quoted multiplicities do not include 195Pt satellites.
J
coupling constants
PtP
(Hz) in parentheses. c Resonance masked by other aromatic signals. Not applicable. e Equivalent to H9. f Equivalent to H8.
d
reaction in inorganic synthesis when reactive organic
functionalities need to be incorporated into the desired
product. The wide applicability of the new methodology
is demonstrated by the preparation of two series of
cationic organoplatinum(II) complexes with hydrogen-
bonding functionality. It greatly expands the avenues
available for the synthesis of the subunits that are
required in the construction of hybrid supramolecular
entities, for which the combination of both the coordina-
tion and hydrogen-bonding motifs vastly increases the
versatility of self-assembly as a tool for supramolecular
architecture. Studies of the self-association character-
istics of selected complexes in low-polarity solvents are
planned.
Exp er im en ta l Section
Gen er a l Meth od s. All procedures were performed under
an inert atmosphere of high-purity N2 using standard Schlenk
techniques. CH2Cl2 and THF were distilled from CaH2 and
sodium metal, respectively. Toluene was predried over CaSO4,
followed by distillation from sodium metal. 3- and 4-iodoben-
zoic acid were purified by recrystallization from toluene and
ethanol, respectively, and dried in a desiccator over P2O5. All

Cationic Organoplatinum(II) Complexes
Organometallics, Vol. 20, No. 16, 2001 3379
1D NMR spectra were recorded at 298 K by means of a Varian
Gemini 2000 NMR spectrometer (1H at 300.10 MHz, 31P at
121.50 MHz, and 195Pt at 64.38 MHz). 2D and VT 1H NMR
spectroscopy experiments were performed on a Varian Unity
INOVA 600 MHz NMR instrument. 1H chemical shifts are
reported in ppm relative to TMS. 31P{1H} and 195Pt{1H} NMR
spectra were referenced to a sealed external standard of 85%
H3PO4 and Na2[PtCl6] in D2O, respectively. Electrospray mass
spectra were obtained using a Finnegan LCQ mass spectrom-
eter, in the positive ion mode, using HPLC grade methanol as
the solvent. Melting points were determined using a Kofler
hot-stage apparatus under a Reichert microscope, and are
uncorrected. IR spectra were recorded on a Perkin-Elmer FT-
IR 1920x spectrophotometer. Elemental analyses were deter-
mined by Chemical and Micro Analytical Services, Pty. Ltd.,
Victoria (Australia). Tetrakis(triphenylphosphine)platinum-
(0)17 and 1,1-bis(4-pyridyl)ethene18 were prepared according
to the literature procedures.
ter t-Bu tyld ip h en ylsilyl-3-iod oben zoa te (1). A solution
of N-methylmorpholine (0.44 mL, 4.04 mmol) and tert-butyl-
chlorodiphenylsilane (1.05 mL, 4.04 mmol) in THF (5 mL) was
added dropwise to a stirred solution of 3-iodobenzoic acid (1.00
g, 4.03 mmol) in THF (10 mL). The resulting solution was
stirred at room temperature for 20 h, during which time a
white precipitate had formed. The mixture was filtered off,
the solvent was removed in vacuo, and the residual oil was
eluted through a plug of silica gel (n-hexane/CH2Cl2, 2:1). The
solvent was removed in vacuo to afford 1 as a white solid (1.92
g, 98%). An analytical sample was recrystallized from CH2-
Cl2/ethanol to yield colorless crystals: mp 70-72 °C; IR (KBr)
3075, 3048, 3033 ν(Ar-H), 2958, 2930, 2893, 2858 ν(C-H),
tr a n s-Iod o(ter t-b u t yld ip h en ylsilyl b en zoa t e-C4)b is-
(tr ip h en ylp h osp h in e)p la tin u m (II) (4). Following a proce-
dure similar to that described for 3, tert-butyldiphenylsilyl-4-
iodobenzoate (0.99 g, 2.04 mmol) in toluene was reacted with
Pt(PPh3)4 (2.03 g, 1.70 mmol) to give 4 as an off-white solid
(1.97 g, 96%): mp 127-129 °C; IR (KBr) 3051 ν(dC-H), 2929,
2892 ν(C-H), 1695 ν(CdO), 1577, 1480, 1434 ν(CdC) cm-1
;
1H NMR (CDCl3) δ 7.72-7.22 (m, 40H, PPh3, SiPh), 6.88-6.80
(m, 4H, AA′BB′, ArH), δ 1.12 (s, 9H, CH3); 31P{1H} NMR
1
(CDCl3) δ 21.4 (s, J PPt ) 3021 Hz); 195Pt{1H} NMR (CDCl3) δ
1
-4700 (t, J PtP ) 3027 Hz). Anal. Calcd for C59H53IO2P2PtSi:
C, 58.66; H, 4.59. Found: C, 58.76; H, 4.43.
tr a n s-(Nicotin ic acid)(ter t-bu tyldiph en ylsilyl ben zoate-
C3)bis(tr ip h en ylp h osp h in e)p la tin u m (II) Tr ifla te (5). To
a stirred solution of 3 (0.250 g, 0.21 mmol) in CH2Cl2 (20 mL)
was added AgOTf (0.053 g, 0.21 mmol), and the mixture was
stirred at room temperature for 16 h in the absence of light.
AgI was filtered off using Celite filter-aid, and the solvent was
reduced in vacuo to ca. 5 mL. Nicotinic acid (0.023 g, 0.19
mmol) was added, and the mixture was stirred at room
temperature for 17 h. The solvent was removed in vacuo to
afford 5 as a white solid (0.239 g, 86%). An analytical sample
was recrystallized from CH2Cl2/diethyl ether: IR (Nujol) 3394
ν(O-H), 1729, 1709 ν(CdO), 1607, 1587, 1562, 1434 ν(CdC,
CdN) 1252, 1220, 1187, 1158, 1039 (OTf) cm-1
;
1H NMR
3
(CDCl3) δ 8.48 (bs, 1H, H2), 8.13 (d, 1H, J HH ) 5.4 Hz, H6),
7.87 (d, 1H, 3J HH ) 7.8 Hz, H4), 7.65-7.19 (m, 42H, PPh3, SiPh,
H,8 H12), 7.05 (d, 1H, 3J HH ) 7.8 Hz, H10), 6.82 (dd, 1H, 3J HH
)
3
3
5.4 Hz, 1H, J HH ) 7.8 Hz, H5), 6.49 (t, 1H, J HH ) 7.8 Hz,
H11), 1.16 (s, 9H, CH3); 31P{1H} NMR (CDCl3) δ 21.2 (s, J PPt
1
) 2976 Hz); 195Pt{1H} NMR (CDCl3) δ -4325 (t, J PtP ) 2971
1
1707 ν(CdO), 1588, 1568, 1558, 1472, 1461, 1428 ν(CdC) cm-1
;
Hz). Anal. Calcd for C66H58F3NO7P2PtSSi: C, 58.66; H, 4.33;
N, 1.04. Found: C, 58.64; H, 4.49; N, 0.99.
4
1H NMR (CDCl3) δ 8.47 (t, 1H, J HH ) 1.5 Hz, H2), 8.10 (dt,
3
4
3
1H, J HH ) 7.9 Hz, J HH ) 1.5 Hz, H6), 7.92 (dt, 1H, J HH
)
tr a n s-(Nicotin ic acid)(ter t-bu tyldiph en ylsilyl ben zoate-
C4)bis(tr ip h en ylp h osp h in e)p la tin u m (II) Tr ifla te (6). Fol-
lowing a procedure similar to that described for 5, complex 4
(0.250 g, 0.21 mmol) in CH2Cl2 was treated with AgOTf (0.053
g, 0.21 mmol), followed by nicotinic acid (0.023 g, 0.19 mmol),
to give 6 as a white solid (0.228 g, 83%): IR (Nujol) 3457 ν-
(O-H), 1729, 1699 ν(CdO), 1608, 1581, 1435 ν(CdC, CdN),
4
3
7.9 Hz, J HH ) 1.5 Hz, H4), 7.22 (t, 1H, J HH ) 7.9 Hz, H5),
7.74-7.70 (m, 4H, SiPh), 7.48-7.37 (m, 6H, SiPh), 1.19 (s, 9H,
CH3). Anal. Calcd for C23H23IO2Si: C, 56.79; H, 4.77. Found:
C, 56.61; H, 4.87.
ter t-Bu tyld ip h en ylsilyl-4-iod oben zoa te (2). Following a
procedure similar to that described for 1, 4-iodobenzoic acid
(1.00 g, 4.03 mmol) in THF solution was reacted with N-
methylmorpholine (0.44 mL, 4.04 mmol) and tert-butylchlo-
rodiphenylsilane (1.05 mL, 4.04 mmol) to give 2 as a white
solid (1.69 g, 86%): mp 119-120 °C; IR (KBr) 3091, 3072, 3031
ν(dC-H), 2952, 2934, 2893, 2857 ν(C-H), 1702 ν(CdO), 1583,
1479, 1472, 1463, 1428 ν(CdC) cm-1; 1H NMR (CDCl3) δ 7.89
(s, 4H, ArH), 7.82-7.75 (m, 4H, SiPh), 7.53-7.41 (m, 6H,
SiPh), 1.23 (s, 9H, CH3). Anal. Calcd for C23H23IO2Si: C, 56.79;
H, 4.77. Found: C, 56.89; H, 4.87.
1280, 1261, 1224, 1176, 1159, 1030 (OTf) cm-1
;
1H NMR
3
(CDCl3) δ 8.52 (s, 1H, H2), 8.22 (d, 1H, J HH ) 4.7 Hz, H6),
7.85 (d, 1H, 3J HH ) 8.0 Hz, H4), 7.70-7.67 (m, 4H, SiPh), 7.47-
7.24 (m, 36H, PPh3, SiPh), 7.08 (2H, AA′ portion of AA′XX′,
H8,12), 6.90 (2H, XX′ portion of AA′XX′, H9,11), 6.84 (dd, 1H,
3
3J HH ) 4.7 Hz, J HH ) 8.0 Hz, H5), 1.14 (s, 9H, CH3); 31P{1H}
1
NMR (CDCl3) δ 20.8 (s, J PPt ) 2985 Hz); 195Pt{1H} NMR
(CDCl3) δ -4299 (t, 1J PtP ) 2974 Hz). Anal. Calcd for C66H58F3-
NO7P2PtSSi: C, 58.66; H, 4.33; N, 1.04. Found: C, 58.42; H,
4.37; N, 0.97.
tr a n s-Iod o(ter t-b u t yld ip h en ylsilyl b en zoa t e-C3)b is-
(tr ip h en ylp h osp h in e)p la tin u m (II) (3). tert-Butyldiphenyl-
silyl-3-iodobenzoate (0.67 g, 1.40 mmol) in toluene (60 mL) was
added to Pt(PPh3)4 (1.50 g, 1.25 mmol). The resulting mixture
was stirred at 75 °C for 14 h. After allowing the solution to
cool to room temperature, the solvent was reduced in vacuo
to ca. 15 mL, and n-hexane (50 mL) was added to precipitate
the product as an off-white solid. The product was filtered off,
washed with n-hexane, and dried in vacuo (1.43 g, 98%). An
analytical sample was recrystallized from CH2Cl2/n-hexane to
yield colorless crystals: mp 248-249 °C; IR (KBr) 3073, 3054
ν(Ar-H), 2954, 2930, 2856 ν(C-H), 1699 ν(CdO), 1560, 1480,
tr a n s-(Ison icotin ic a cid )(ter t-bu tyld ip h en ylsilyl ben -
zoa te-C3)bis(tr ip h en ylp h osp h in e)p la tin u m (II) Tr ifla te
(7). Following a procedure similar to that described for 5,
complex 3 (0.250 g, 0.21 mmol) in CH2Cl2 was treated with
AgOTf (0.053 g, 0.21 mmol), followed by isonicotinic acid (0.023
g, 0.19 mmol), to give 7 as a white solid (0.238 g, 86%): IR
(Nujol) 3384 ν(O-H), 1728, 1698 ν(CdO), 1617, 1588, 1560,
1438 ν(CdC, CdN), 1279, 1254, 1224, 1164, 1030 (OTf) cm-1
;
1H NMR (CDCl3) δ 8.12 (2H, AA′ portion of AA′XX′, H2,6), 7.64-
3
7.12 (m, 44H, PPh3, SiPh, H,3,5 H,8 H12), 7.07 (d, 1H, J HH
)
7.8 Hz, H10), 6.47 (t, 1H, 3J HH ) 7.8 Hz, H11), 1.15 (s, 9H, CH3);
1464, 1434 ν(CdC) cm-1
;
1H NMR (CDCl3) δ 7.74-7.17 (m,
31P{1H} NMR (CDCl3) δ 21.0 (s, J PPt ) 2985 Hz); 195Pt{1H}
1
3
41H, PPh3, SiPh, H2), 7.08 (d, 1H, J HH ) 7.8 Hz, H6), 7.03 (d,
1
NMR (CDCl3) δ -4314 (t, J PtP ) 2985 Hz). Anal. Calcd for
3
3
1H, J HH ) 7.8 Hz, H4), 6.28 (t, 1H, J HH ) 7.8 Hz, H5), 1.13
C
66H58 F3NO7P2PtSSi: C, 58.66; H, 4.33; N, 1.04. Found: C,
(s, 9H, CH3); 31P{1H} NMR (CDCl3) δ 22.0 (s, 1J PPt ) 3024 Hz);
58.49; H, 4.46; N, 0.98.
195Pt{1H} NMR (CDCl3) δ -4732 (t, J PtP ) 3024 Hz). Anal.
1
tr a n s-(Ison icotin ic a cid )(ter t-bu tyld ip h en ylsilyl ben -
zoa te-C4)bis(tr ip h en ylp h osp h in e)p la tin u m (II) Tr ifla te
(8). Following a procedure similar to that described for 5,
complex 4 (0.250 g, 0.21 mmol) in CH2Cl2 was treated with
AgOTf (2.03 g, 1.70 mmol), followed by isonicotinic acid (0.023
g, 0.19 mmol), to give 8 as a white solid (0.226 g, 82%): IR
Calcd for C59H53IO2P2PtSi: C, 58.76; H, 4.43. Found: C, 58.75;
H, 4.47.
(17) Ugo, R.; Cariati, F.; La Monica, G. Inorg. Synth. 1990, 28, 123.
(18) Fujita, M.; Aoyagi, M.; Ogura, K. Inorg. Chim. Acta 1996, 246,
53.

3380 Organometallics, Vol. 20, No. 16, 2001
Gallasch et al.
(Nujol) 3501 ν(O-H), 1708, 1687 ν(CdO), 1616, 1582, 1438
H2,6), 7.47-7.30 (m, 30H, PPh3), 7.24 (2H, XX′ portion of
AA′XX′, H3,5), 6.89 (m, 4H, AA′BB′, H,8,12 H9,11); 31P{1H} NMR
(CD3OD) δ 21.9 (s, 1J PPt ) 2992 Hz); 195Pt{1H} NMR (CD3OD)
ν(CdC, CdN), 1293, 1237, 1177, 1160, 1025 (OTf) cm-1 1H
;
NMR (CDCl3) δ 8.26 (2H, AA′ portion of AA′XX′, H2,6), 7.70-
7.67 (m, 4H, SiPh), 7.47-7.26 (m, 38H, PPh3, SiPh, H3,5), 7.03
(2H, AA′ portion of AA′XX′, H8,12), 6.90 (2H, XX′ portion of
AA′XX′, H9,11), 1.14 (s, 9H, CH3); 31P{1H} NMR (CDCl3) δ 20.7
1
δ -4288 (t, J PtP ) 2984 Hz); ES-MS (m/z) 963 [M - OTf]+,
840 [M - OTf - C4H4N(CO2H)]+, 719 [M - OTf - C5H4N-
(CO2H) - [Pt(PPh3)2C6H4(CO2H)]+]+. Anal. Calcd for C50H40F3-
NO7P2PtS: C, 53.96; H, 3.62; N, 1.26. Found: C, 54.08; H, 3.54;
N, 1.37.
tr a n s-µ-1,1-Bis(4-p yr id yl)et h en eb is[(ter t-b u t yld ip h e-
n ylsilyl ben zoa te-C3)bis(tr ip h en ylp h osp h in e)p la tin u m -
(II)] Bis(tr ifla te) (13). Following a procedure similar to that
described for 5, complex 3 (0.210 g, 0.17 mmol) in CH2Cl2 was
treated with AgOTf (0.045 g, 0.17 mmol) and stirred with 1,1-
bis(4-pyridyl)ethene (0.014 g, 0.078 mmol) for 1 h to give 13
as a white solid (0.202 g, 88%): IR (Nujol) 1695 ν(CdO), 1611,
1
1
(s, J PPt ) 2989 Hz); 195Pt{1H} NMR (CDCl3) δ -4286 (t, J PtP
) 2993 Hz). Anal. Calcd for C66H58F3NO7P2PtSSi: C, 58.66;
H, 4.33; N, 1.04. Found: C, 58.56; H, 4.42; N, 1.02.
tr a n s-(Ben zoic a cid -C3)(n icotin ic a cid )bis(tr ip h en yl-
p h osp h in e)p la tin u m (II) Tr ifla te (9). To a stirred solution
of complex 5 (0.120 g, 0.089 mmol) in CH2Cl2 (2 mL) was added
HOTf (0.85 mL of 0.109 M solution in CH2Cl2, 0.093 mmol).
The mixture was then stirred at room temperature for 2 h.
Diethyl ether was added to precipitate 9 as a white solid, which
was filtered off, washed with diethyl ether, and dried in vacuo
(0.074 g, 75%). An analytical sample was recrystallized from
CH2Cl2/diethyl ether: IR (Nujol) 3425 ν(O-H), 1726, 1684 ν-
(CdO), 1608, 1585, 1560, 1439, 1435 ν(CdC, CdN), 1287, 1263,
1225, 1167, 1027 (OTf) cm-1; 1H NMR (CD3OD) δ 8.58 (s, 1H,
1561 ν(CdC, CdN), 1276, 1260, 1222, 1150, 1030 (OTf) cm-1
;
1H NMR (CDCl3) δ 8.14 (4H, AA′ portion of AA′XX′, H3,5), 7.61-
3
7.19 (m, 64H, PPh3, SiPh, H,8 H12), 6.96 (d, 2H, J HH ) 7.8
Hz, H10) 6.43 (t, 2H, 3J HH ) 7.8 Hz, H11), 6.42 (4H, XX′ portion
of AA′XX′, H2,6), 5.47 (s, 2H, CH2), 1.14 (s, 18H, CH3); 31P{1H}
3
3
1
H2), 8.51 (d, 1H, J HH ) 5.4 Hz, H6), 7.85 (d, 1H, J HH ) 7.8
NMR (CDCl3) δ 21.6 (s, J PPt ) 2989 Hz); 195Pt{1H} NMR
Hz, H4), 7.49-7.27 (m, 31H, PPh3, H8), 7.11 (d, 1H, 3J HH ) 7.8
(CDCl3) δ -4282 (t, J PtP ) 3010 Hz). Anal. Calcd for
1
Hz, H12), 7.04 (d, 1H, J HH ) 7.8 Hz, H10), 6.96 (dd, 1H, J HH
C132H116F6N2O10P4Pt2S2Si2: C, 60.08; H, 4.43; N, 1.06. Found:
3
3
) 7.8 Hz, J HH ) 5.4 Hz, H5), 6.39 (d, 1H, J HH ) 7.8 Hz, H11);
C, 59.90; H, 4.72; N, 1.03.
3
3
31P{1H} NMR (CD3OD) δ 22.6 (s, J PPt ) 2995 Hz); 195Pt{1H}
1
tr a n s-µ-1,1-Bis(4-p yr id yl)et h en eb is[(ter t-b u t yld ip h e-
n ylsilyl ben zoa te-C4)bis(tr ip h en ylp h osp h in e)p la tin u m -
(II)] Bis(tr ifla te) (14). Following a procedure similar to that
described for 5, complex 4 (0.300 g, 0.25 mmol) in CH2Cl2 was
treated with AgOTf (0.064 g, 0.25 mmol) and stirred with 1,1-
bis(4-pyridyl)ethene (0.020 g, 0.11 mmol) for 1 h to give 14 as
a white solid (0.296 g, 88%); IR (Nujol) 1699 ν(CdO), 1611,
1581, 1439 ν(CdC, CdN), 1277, 1261, 1223, 1176, 1151, 1030
(OTf) cm-1; 1H NMR (CDCl3) δ 8.20 (4H, AA′ portion of AA′XX′,
H3,5), 7.70-7.67 (m, 8H, SiPh), 7.43-7.25 (m, 72H, PPh3, SiPh),
7.03 (4H, AA′ portion of AA′XX′, H8,12), 6.82 (4H, XX′ portion
of AA′XX′, H9,11), 6.40 (4H, XX′ portion of AA′XX′, H2,6), 5.45
(s, 2H, CH2), 1.14 (s, 9H, CH3); 31P{1H} NMR (CDCl3) δ 21.2
NMR (CD3OD) δ -4318 (t, 1J PtP ) 3008 Hz); ES-MS (m/z) 963
[M - OTf]+, 840 [M -OTf - C4H4N(CO2H)]+, 719 [M - OTf -
C5H4N(CO2H) - [Pt(PPh3)2C6H4(CO2H)]+]+. Anal. Calcd for
C50H40F3NO7P2PtS: C, 53.96; H, 3.62; N, 1.26. Found: C,
53.79; H, 3.75; N, 1.35.
tr a n s-(Ben zoic a cid -C4)(n icotin ic a cid )bis(tr ip h en yl-
p h osp h in e)p la tin u m (II) Tr ifla te (10). Following a proce-
dure similar to that described for 9, complex 6 (0.110 g, 0.081
mmol) in CH2Cl2 was treated with HOTf (0.55 mL of 0.164 M
solution in CH2Cl2, 0.090 mmol) to give 10 as a white solid
(0.070 g, 77%): IR (Nujol) 3427 (O-H), 1710 ν(CdO), 1610,
1584, 1439 ν(CdC, CdN), 1284, 1254, 1225, 1168, 1030 (OTf)
cm-1; 1H NMR (CD3OD) δ 8.55 (s, 1H, H2), 8.51 (d, 1H, 3J HH
)
(s, J PPt ) 2999 Hz); 195Pt{1H} NMR (CDCl3) δ -4282 (t, J PtP
) 3010 Hz). Anal. Calcd for C132H116F6N2O10P4Pt2S2Si2: C,
60.08; H, 4.43; N, 1.06. Found: C, 59.85; H, 4.50; N, 0.99.
tr a n s-µ-4,7-P h en a n t h r olin ebis[(ter t-b u t yld ip h en ylsi-
lyl ben zoate-C3)bis(tr iph en ylph osph in e)platin u m (II)] Bis-
(tr ifla te) (15). Following a procedure similar to that described
for 5, complex 3 (0.250 g, 0.21 mmol) in CH2Cl2 was treated
with AgOTf (0.053 g, 0.21 mmol) and stirred with 4,7-
phenanthroline (0.017 g, 0.094 mmol) for 1 h to give 15 as a
white solid (0.245 g, 89%): IR (Nujol) 1698 ν(CdO), 1587, 1563,
1439, 1435 ν(CdC, CdN), 1277, 1260, 1223, 1153, 1031 (OTf)
1
1
3
5.1 Hz, H6), 7.84 (d, 1H, J HH ) 7.5 Hz, H4), 7.46-7.26 (m,
30H, Ph), 6.98-6.90 (m, 5H, H,8,12 H,9,11 H5); 31P{1H} NMR
(CD3OD) δ 22.2 (s, 1J PPt ) 2993 Hz); 195Pt{1H} NMR (CD3OD)
1
δ -4297 (t, J PtP ) 2990 Hz); ES-MS (m/z) 963 [M - OTf]+,
840 [M - OTf - C4H4N(CO2H)]+, 719 [M - OTf - C5H4N-
(CO2H) - [Pt(PPh3)2C6H4(CO2H)]+]+. Anal. Calcd for C50H40F3-
NO7P2PtS: C, 53.96; H, 3.62; N, 1.26. Found: C, 53.80; H, 3.86;
N, 1.24.
tr a n s-(Ben zoic a cid -C3)(ison icot in ic a cid )b is(t r ip h -
en ylp h osp h in e)p la tin u m (II) Tr ifla te (11). Following a
procedure similar to that described for 9, complex 7 (0.160 g,
0.12 mmol) in CH2Cl2 was treated with HOTf (1.2 mL of 0.107
M solution in CH2Cl2, 0.13 mmol) to give 11 as a white solid
(0.086 g, 65%): IR (Nujol) 3436 ν(O-H), 1732, 1679 ν(CdO),
1583, 1564, 1438, 1435 ν(CdC, CdN), 1294, 1265, 1230, 1176,
1025 (OTf) cm-1; 1H NMR (CD3OD) δ 8.47 (2H, AA′ portion of
AA′XX′, H2,6), 7.53-7.23 (m, 31H, PPh3, H8), 7.24 (2H, XX′
3
cm-1; 1H NMR (CD3OD) δ 9.82 (s, 2H, H5,6), 9.15 (d, 2H, J HH
3
) 4.2 Hz, H3,8), 9.00 (d, 2H, J HH ) 8.4 Hz, H1,10), 7.76-7.10
(m, 88H, PPh3, SiPh, H,2,9 H,12 H,14 H16), 6.40 (bs, 2H, H15),
1
1.14 (s, 18H, CH3); 31P{1H} NMR (CDCl3) δ 19.9 (s, J PPt
)
3029 Hz); 195Pt{1H} NMR (CDCl3) δ -4267 (t, J PtP ) 2974
Hz). Anal. Calcd for C132H114F6N2O10P4Pt2S2Si2: C, 60.13; H,
4.36; N, 1.06. Found: C, 59.99; H, 4.58; N, 1.06.
1
3
portion of AA′XX′, H3,5), 7.10 (d, 1H, J HH ) 7.5 Hz, H12), 6.95
tr a n s-µ-4,7-P h en a n t h r olin ebis[(ter t-b u t yld ip h en ylsi-
lyl ben zoate-C4)bis(tr iph en ylph osph in e)platin u m (II)] Bis-
(tr ifla te) (16). Following a procedure similar to that described
for 5, complex 4 (0.300 g, 0.25 mmol) in CH2Cl2 was treated
with AgOTf (0.064 g, 0.25 mmol) and stirred with 4,7-
phenanthroline (0.020 g, 0.11 mmol) for 1 h to give 16 as a
white solid (0.289 g, 88%): IR (Nujol) 1700 ν(CdO), 1582, 1439
3
3
(d, 1H, J HH ) 7.5 Hz, H10), 6.36 (t, 1H, J HH ) 7.8 Hz, H11);
31P{1H} NMR (CD3OD) δ 22.2 (s, J PPt ) 2990 Hz); 195Pt{1H}
1
NMR (CD3OD) δ -4309 (t, 1J PtP ) 2993 Hz). ES-MS (m/z): 963
[M - OTf]+, 840 [M - OTf - C4H4N(CO2H)]+, 719 [M - OTf
- C5H4N(CO2H) - [Pt(PPh3)2C6H4(CO2H)]+]+. Anal. Calcd for
C
50H40F3NO7P2PtS: C, 53.96; H, 3.62; N, 1.26. Found: C,
ν(CdC, CdN), 1279, 1262, 1223, 1180, 1153, 1031 (OTf) cm-1
;
53.65; H, 3.25; N, 1.27.
tr a n s-(Ben zoic a cid -C4)(ison icot in ic a cid )b is(t r ip h -
en ylp h osp h in e)p la tin u m (II) Tr ifla te (12). Following a
procedure similar to that described for 9, complex 8 (0.060 g,
0.044 mmol) in CH2Cl2 was reacted with HOTf (0.45 mL of
0.107 M solution in CH2Cl2, 0.048 mmol) to give 12 as a white
solid (0.036 g, 73%); IR (Nujol) 3407 ν(O-H), 1702 ν(CdO),
1583, 1438, ν(CdC, CdN), 1282, 1225, 1183, 1154, 1032 (OTf)
1H NMR (CD3OD) δ 9.83 (s, 2H, H5,6), 9.12 (d, 2H, J HH ) 5.1
Hz, H3,8), 9.03 (d, 2H, 3J HH ) 8.7 Hz, H1,10), 7.73-7.17 (m, 82H,
PPh3, SiPh, H2,9), 6.94 (bs, 8H, H,12,16 H13,15), 1.12 (s, 18H, CH3);
3
3
1H NMR (CD2Cl2) δ 9.95 (s, 2H, H5,6), 8.96 (d, 2H, J HH ) 8.4
Hz, H1,10), 8.70 (d, 2H, 3J HH ) 5.4 Hz, H3,8), 7.69-7.66 (m, 8H,
SiPh), 7.50-7.13 (m, 82H, PPh3, SiPh, H,2,9 H,12,16 H13,15), 1.14
1
(s, 18H, CH3); 31P{1H} NMR (CDCl3) δ 19.9 (s, J PPt ) 3026
cm-1
;
1H NMR (CD3OD) δ 8.46 (2H, AA′ portion of AA′XX′,
Hz); (CD2Cl2) 21.7 (s, 1J PPt ) 3007 Hz); 195Pt{1H} NMR (CDCl3)

Cationic Organoplatinum(II) Complexes
Organometallics, Vol. 20, No. 16, 2001 3381
δ -4237 (t, 1J PtP ) 3035 Hz). Anal. Calcd for C132H114F6N2O10P4-
Pt2S2Si2: C, 60.13; H, 4.36; N, 1.06. Found: C, 59.92; H, 4.52;
N, 0.97.
tr a n s-µ-4,7-P h en a n t h r olin eb is[(b en zoic a cid -C3)b is-
(tr ip h en ylp h osp h in e)p la tin u m (II)] Bis(tr ifla te) (21). Fol-
lowing a procedure similar to that described for 9, complex 15
(0.090 g, 0.034 mmol) in CH2Cl2 was treated with HOTf (0.45
mL of 0.164 M solution in CH2Cl2, 0.074 mmol) to give 21 as
a white solid (0.058 g, 79%): IR (Nujol) 3399 ν(O-H), 1699
ν(CdO), 1585, 1562, 1493, 1439, 1435 ν(CdC, CdN), 1281,
tr a n s-µ-4,4′-Bipyr idin ebis[(ter t-bu tyldiph en ylsilyl ben -
zoa te-C3)bis(tr ip h en ylp h osp h in e)p la tin u m (II)] Bis(tr i-
fla te) (17). Following a procedure similar to that described
for 5, complex 3 (0.250 g, 0.21 mmol) in CH2Cl2 was treated
with AgOTf (0.053 g, 0.21 mmol) and stirred with 4,4′-
bipyridine (0.015 g, 0.093 mmol) for 1 h to give 17 as a white
solid (0.240 g, 88%): IR (Nujol) 1699 ν(CdO), 1611, 1559, 1439
1
1267, 1225, 1156, 1030 (OTf) cm-1; H NMR (CD3OD) δ 9.94
3
(s, 2H, H5,6), 9.16 (d, 2H, J HH ) 4.5 Hz, H3,8), 9.02 (d, 2H,
3J HH ) 8.4 Hz, H1,10), 7.41-7.16 (m, 66H, PPh3, H,2,9 H,12 H16),
ν(CdC, CdN), 1276, 1262, 1223, 1151, 1030 (OTf) cm-1 1H
;
3
7.04 (d, 2H, J HH ) 7.8 Hz, H14), 6.28 (bs, 2H, H15); 31P{1H}
NMR (CDCl3) δ 8.17 (4H, AA′ portion of AA′XX′, H3,5), 7.64-
7.19 (m, 64H, PPh3, SiPh, H,8 H12), 7.09 (4H, XX′ portion of
1
NMR (CD3OD) δ 21.1 (s, J PPt ) 2989 Hz); 195Pt{1H} NMR
1
(CD3OD) δ -4274 (t, J PtP ) 2961 Hz); ES-MS (m/z) 1020 [M
3
AA′XX′, H2,6), 6.94 (d, 2H, J HH ) 7.8 Hz, H10), 6.45 (t, 2H,
- 2OTf - [Pt(PPh3)2C6H4(CO2H)]+]+, 840 [M - 2OTf - [Pt-
(PPh3)2C6H4(CO2H)]+ - C12H8N2]+, 719 [M - 2OTf - [Pt-
(PPh3)2C6H4(CO2H)]+ - C12H8N2 - C6H4(CO2H)]+. Anal. Calcd
for C100H78F6N2O10P4Pt2S2: C, 55.61; H, 3.64; N, 1.30. Found:
C, 55.62; H, 3.55; N, 1.32.
3J HH ) 7.8 Hz, H11), 1.15 (s, 18H, CH3); 31P{1H} NMR (CDCl3)
1
δ 21.1 (s, J PPt ) 2981 Hz); 195Pt{1H} NMR (CDCl3) δ -4311
1
(t, J PtP ) 2980 Hz). Anal. Calcd for C130H114F6N2O10P4Pt2S2-
Si2: C, 59.76; H, 4.40; N, 1.07. Found: C, 59.58; H, 4.47; N,
1.10.
tr a n s-µ-4,7-P h en an th r olin ebis[(ben zoic acid-C4)bis(tr i-
p h en ylp h osp h in e)p la tin u m (II)] Bis(tr ifla te) (22). Follow-
ing a procedure similar to that described for 9, complex 16
(0.160 g, 0.061 mmol) in CH2Cl2 was treated with HOTf (0.75
mL of 0.164 M solution in CH2Cl2, 0.12 mmol) to give 22 as a
white solid (0.112 g, 85%): IR (Nujol) 3427 ν(O-H), 1688 ν-
(CdO), 1584, 1490, 1481, 1439 ν(CdC, CdN), 1276, 1265, 1224,
1180, 1155, 1032 (OTf) cm-1; 1H NMR (CD3OD) δ 9.86 (s, 2H,
tr a n s-µ-4,4′-Bipyr idin ebis[(ter t-bu tyldiph en ylsilyl ben -
zoa te-C4)bis(tr ip h en ylp h osp h in e)p la tin u m (II)] Bis(tr i-
fla te) (18). Following a procedure similar to that described
for 5, complex 4 (0.300 g, 0.25 mmol) in CH2Cl2 was treated
with AgOTf (0.064 g, 0.25 mmol) and stirred with 4,4′-
bipyridine (0.018 g, 0.11 mmol) for 1 h to give 18 as a white
solid (0.276 g, 85%): IR (Nujol) 1699 ν(CdO), 1609, 1581 ν-
(CdC, CdN), 1278, 1260, 1224, 1176, 1152, 1030 (OTf) cm-1
;
3
3
H5,6), 9.10 (d, 2H, J HH ) 4.8 Hz, H3,8), 8.99 (d, 2H, J HH ) 9.0
1H NMR (CDCl3) δ 8.21 (4H, AA′ portion of AA′XX′, H3,5), 7.70-
7.67 (m, 8H, SiPh), 7.47-7.25 (m, 72H, PPh3, SiPh), 7.08 (4H,
XX′ portion of AA′XX′, H2,6), 7.06 (4H, AA′ portion of AA′XX′,
H8,12), 6.82 (4H, XX′ portion of AA′XX′, H9,11), 1.14 (s, 18H,
Hz, H1,10), 7.42-7.16 (m, 62H, PPh3, H2,9), 6.86 (bs, 8H, AA′BB′,
H,12,16 H13,15); 31P{1H} NMR (CD3OD) δ 21.0 (s, J PPt ) 2978
1
Hz); 195Pt{1H} NMR (CD3OD) δ -4252 (t, J PtP ) 2990 Hz);
1
ES-MS (m/z) 1020 [M - 2OTf - [Pt(PPh3)2C6H4(CO2H)]+]+, 840
[M - 2OTf -[Pt(PPh3)2C6H4(CO2H)]+ - C12H8N2]+, 719 [M -
2OTf - [Pt(PPh3)2C6H4(CO2H)]+ - C12H8N2 - C6H4(CO2H)]+.
Anal. Calcd for C100H78F6N2O10P4Pt2S2: C, 55.61; H, 3.64; N,
1.30. Found: C, 55.64; H, 3.55; N, 1.40.
1
195
CH3); 31P{1H} NMR (CDCl3) δ 20.7 (s, J PPt ) 2971 Hz);
-
Pt{1H} NMR (CDCl3) δ -4284 (t, 1J PtP ) 2986 Hz). Anal. Calcd
for C130H114F6N2O10P4Pt2S2Si2: C, 59.76; H, 4.40; N, 1.07.
Found: C, 59.64; H, 4.50; N, 0.95.
tr a n s-µ-1,1-Bis(4-pyr idyl)eth en ebis[(ben zoic acid-C3)bis-
(tr ip h en ylp h osp h in e)p la tin u m (II)] Bis(tr ifla te) (19). Fol-
lowing a procedure similar to that described for 9, complex 13
(0.090 g, 0.034 mmol) in CH2Cl2 was treated with HOTf (0.70
mL of 0.104 M solution in CH2Cl2, 0.073 mmol) to give 19 as
a white solid (0.053 g, 72%): IR (Nujol) 3406 ν(O-H), 1700
ν(CdO), 1612, 1561, 1480, 1439, 1435 ν(CdC, CdN), 1277,
tr a n s-µ-4,4′-Bipyr idin ebis[(ben zoic acid-C3)bis(tr iph en -
ylp h osp h in e)p la tin u m (II)] Bis(tr ifla te) (23). Following a
procedure similar to that described for 9, complex 17 (0.150
g, 0.057 mmol) in CH2Cl2 was treated with HOTf (1.1 mL of
0.109 M solution in CH2Cl2, 0.12 mmol) to give 23 as a white
solid (0.101 g, 82%): IR (Nujol) 3398 ν(O-H), 1700 ν(CdO),
1611, 1559, 1439, 1435 ν(CdC, CdN), 1279, 1258, 1224, 1166,
1030 (OTf) cm-1; 1H NMR (CD3OD) δ 8.39 (4H, AA′ portion of
AA′XX′, H2,6), 7.47-7.27 (m, 61H, PPh3, H8), 7.11 (d, 2H, 3J HH
1
1260, 1224, 1159, 1030 (OTf) cm-1; H NMR (CD3OD) δ 8.29
(4H, AA′ portion of AA′XX′, H2,6), 7.49-7.30 (m, 60H, PPh3),
3
3
7.12 (d, 2H, J HH ) 7.5 Hz, H12), 6.96 (d, 2H, J HH ) 7.5 Hz,
3
) 7.8 Hz, H12), 6.96 (d, 2H, J HH ) 7.8 Hz, H10), 6.84 (4H, XX′
H10), 6.38 (4H, XX′ portion of AA′XX′, H3,5), 6.37 (t, 2H, J HH
3
3
portion of AA′XX′, H3,5), 6.38 (t, 2H, J HH ) 7.8 Hz, H11); 31P-
) 7.5 Hz, H11), 5.59 (s, 2H, CH2); 31P{1H} NMR (CD3OD) δ
22.4 (s, 1J PPt ) 3002 Hz); 195Pt{1H} NMR (CD3OD) δ -4310 (t,
1J PtP ) 2992 Hz); ES-MS (m/z) 1022 [M - 2OTf - [Pt-
(PPh3)2C6H4(CO2H)]+]+, 840 [M - 2OTf - [Pt(PPh3)2C6H4-
(CO2H)]+ - C12H10N2]+, 719 [M - 2OTf - [Pt(PPh3)2C6H4-
(CO2H)]+ - C12H10N2 - C6H4(CO2H)]+. Anal. Calcd for
{1H} NMR (CD3OD) δ 22.2 (s, 1J PPt ) 2985 Hz); 195Pt{1H} NMR
1
(CD3OD) δ -4310 (t, J PtP ) 3009 Hz); ES-MS (m/z) 996 [M -
2OTf - [Pt(PPh3)2C6H4(CO2H)]+]+, 840 [M - 2OTf - [Pt-
(PPh3)2C6H4(CO2H)]+ - C10H8N2]+, 719 [M - 2OTf - [Pt-
(PPh3)2C6H4(CO2H)]+ - C10H8N2 - C6H4(CO2H)]+. Anal. Calcd
for C98H78F6N2O10P4Pt2S2: C, 55.11; H, 3.68; N, 1.31. Found:
C, 54.84; H, 3.90; N, 1.26.
C
100H80F6N2O10P4Pt2S2: C, 55.56; H, 3.73; N, 1.30. Found: C,
55.47; H, 3.89; N, 1.33.
tr a n s-µ-4,4′-Bipyr idin ebis[(ben zoic acid-C4)bis(tr iph en -
ylp h osp h in e)p la tin u m (II)] Bis(tr ifla te) (24). Following a
procedure similar to that described for 9, complex 18 (0.130
g, 0.050 mmol) in CH2Cl2 was treated with HOTf (0.95 mL of
0.107 M solution in CH2Cl2, 0.10 mmol) to give 24 as a white
solid (0.105 g, 99%); IR (Nujol) 3413 ν(O-H), 1700 ν(CdO),
1611, 1583, 1439, 1435 ν(CdC, CdN), 1282, 1260, 1225, 1176,
1030 (OTf) cm-1; 1H NMR (CD3OD) δ 8.36 (4H, AA′ portion of
AA′XX′, H2,6), 7.46-7.30 (m, 60H, PPh3), 6.90 (m, 8H, AA′BB′,
H,8,12 H9,11), 6.83 (4H, XX′ portion of AA′XX′, H3,5); 31P{1H}
tr a n s-µ-1,1-Bis(4-pyr idyl)eth en ebis[(ben zoic acid-C4)bis-
(tr ip h en ylp h osp h in e)p la tin u m (II)] Bis(tr ifla te) (20). Fol-
lowing a procedure similar to that described for 9, complex 14
(0.090 g, 0.044 mmol) in CH2Cl2 was treated with HOTf (0.65
mL of 0.107 M solution in CH2Cl2, 0.070 mmol) to give 20 as
a white solid (0.069 g, 93%): IR (Nujol) 3419 ν(O-H), 1700
ν(CdO), 1612, 1583, 1439 ν(CdC, CdN), 1279, 1260, 1224,
1159, 1030 (OTf) cm-1 1H NMR (CD3OD) δ 8.28 (4H, AA′
;
portion of AA′XX′, H2,6), 7.49-7.31 (m, 60H, PPh3), 6.90 (m,
8H, AA′BB′, H,8,12 H9,11), 6.36 (4H, XX′ portion of AA′XX′, H3,5),
1
NMR (CD3OD) δ 21.9 (s, J PPt ) 2990 Hz); 195Pt{1H} NMR
1
5.58 (s, 2H, CH2); 31P{1H} NMR (CD3OD) δ 22.1 (s, J PPt
)
1
3000 Hz); 195Pt{1H} NMR (CD3OD) δ -4288 (t, J PtP ) 3016
Hz); ES-MS (m/z) 1022 [M - 2OTf - [Pt(PPh3)2C6H4(CO2H)]+]+,
840 [M - 2OTf - [Pt(PPh3)2C6H4(CO2H)]+ - C12H10N2]+, 719
[M - 2OTf - [Pt(PPh3)2C6H4(CO2H)]+ - C12H10N2 - C6H4-
(CO2H)]+. Anal. Calcd for C100H80F6N2O10P4Pt2S2: C, 55.56; H,
3.73; N, 1.30. Found: C, 55.47; H, 4.09; N, 1.27.
1
(CD3OD) δ -4288 (t, J PtP ) 2979 Hz); ES-MS (m/z) 996 [M -
2OTf - [Pt(PPh3)2C6H4(CO2H)]+]+, 840 [M - 2OTf - [Pt-
(PPh3)2C6H4(CO2H)]+ - C10H8N2]+, 719 [M - 2OTf - [Pt-
(PPh3)2C6H4(CO2H)]+ - C10H8N2-C6H4(CO2H)]+. Anal. Calcd
for C98H78F6N2O10P4Pt2S2‚CH2Cl2: C, 53.54; H, 3.63; N, 1.26.
Found: C, 53.71; H, 3.81; N, 1.50.

3382 Organometallics, Vol. 20, No. 16, 2001
Gallasch et al.
X-r a y Cr ysta llogr a p h y. Suitable crystals of complex 3
were grown from CH2Cl2/n-hexane by means of diffusion
layering techniques. Data for a colorless crystal of 3 (11 × 0.15
× 0.40 mm) were collected at 173 K employing graphite-
monochromatized Mo KR radiation (λ ) 0.71073 Å) on a
Rigaku AFC7R diffractometer. Corrections were made for
Lorentz and polarization effects19 and for absorption using an
empirical procedure.20
Cr ysta l d a ta for 3: C59H53IO2P2PtSi, M ) 1206.1, orthor-
hombic, P212121, a ) 12.014(4) Å, b ) 36.823(8) Å, c ) 11.614-
(4) Å, V ) 5138(3) Å3, Z ) 4, Dx ) 1.559 g cm-3, T ) 173 K,
µ(Mo KR) ) 34.49 cm-1, 12 249 reflections measured, θmax
27.5°, 9051 unique, 5031 with I g 2.0σ(I).
mined by comparing the refinements for both hands. The
structure reported herein had a significantly reduced value of
Rw. Figure 1 shows a diagram of the molecule that was drawn
with ORTEP22 at the 50% probability level. PLATON23 was
also used in the analysis of crystal structure.
Ack n ow led gm en t. We thank Mr. Phil Clements for
1
recording the 2D and VT H NMR spectra, Ms. Susan
Woodhouse for recording the ESI mass spectra, Dr.
Daniela Caiazza for preparing the 1,1-bis(4-pyridyl)-
ethene ligand, and Dr. Simon Pyke for useful NMR
discussions. We are grateful to the Australian Research
Council (ARC) for financial support.
The structure was solved by heavy-atom methods21 and
refined by a full-matrix least-squares procedure based on F.19
Non-hydrogen atoms were refined with anisotropic displace-
ment parameters, and H atoms were included in the model in
their calculated positions (C-H 0.95 Å). The refinement was
continued until convergence with the application of a weight-
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic data file for 3, including atomic coordinates, bond
distances and angles, and thermal parameters, is available
in CIF format. This material is available free of charge via
the Internet at http://pubs.acs.org.
2
ing scheme of the form w ) 1/[σ2(Fo) + 0.00001|Fo| ] when R
) 0.030 and Rw ) 0.029. The absolute structure was deter-
OM010127C
(19) teXsan: Structure Analysis Software; Molecular Structure
Corp.: The Woodlands, TX, 1997.
(20) Walker, N.; Stuart, D. Acta Crystallogr. Sect. A 1983, 39, 158.
(21) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garc´ıa-Granda, S.; Smits, J . M. M.; Smykalla, C. The DIRDIF program
system, Technical Report of the Crystallography Laboratory; University
of Nijmegen: The Netherlands, 1992.
(22) J ohnson, C. K. ORTEP. Report ORNL-5138; Oak Ridge Na-
tional Laboratory: TN, 1976.
(23) Spek, A. L. PLATON, A Multipurpose Crystallographic Tool;
Utrecht University: Utrecht, The Netherlands, 2000; http://ww-
w.cryst.chem.uu.nl/platon/.