Synthesis, reactivity, spectroscopic characterization, X-ray structures, PGSE, and NOE NMR studies of (η5-C5Me 5)-rhodium and -iridium derivatives containing bis(pyrazolyl)alkane ligands

Article abstract of DOI:10.1021/ic061928g

Rhodium(III) and iridium(III) complexes containing bis(pyrazolyl)methane ligands (pz = pyrazole, L′ in general; specifically, L¹ = H₂C(pz)₂, L² = H₂C(pz ^Me2)₂, L³ = H₂C(pz ^4Me)₂, L⁴ = Me₂C(pz)₂), have been prepared in a study exploring the reactivity of these ligands toward [Cp*MCl(μ-Cl)]₂ dimers (M = Rh, Ir; Cp* = pentamethylcyclopentadienyl). When the reaction was carried out in acetone solution, complexes of the type [Cp*M(L′)Cl]Cl were obtained. However, when L¹ and L² ligands have been employed with excess [Cp*MCl(μ-Cl)]₂, the formation of [Cp*M(L′)-Cl][Cp*MCl₃] species has been observed. PGSE NMR measurements have been carried out for these complexes, in which the counterion is a cyclopentadienyl metal complex, in CD₂Cl₂ as a function of the concentration. The hydrodynamic radius (r_H) and, consequently, the hydrodynamic volume (V_H) of all the species have been determined from the measured translational self-diffusion coefficients (D_t), indicating the predominance of ion pairs in solution. NOE measurements and X-ray single-crystal studies suggest that the [Cp*MCl₃]^- approaches the cation, orienting the three Cl-legs of the piano-stool toward the CH₂ moieties of the bis(pyrazolyl)methane ligands. The reaction of 1 equiv of [Cp*M(L′)Cl]Cl or [Cp*M(L′)Cl][Cp*MCl₃] with 1 equiv of AgX (X = ClO₄ or CF₃SO₃) in CH₂Cl₂ allows the generation of [Cp*M(L′)Cl]X, whereas the reaction of 1 equiv of [Cp*M(L′)Cl] with 2 equiv of AgX yields the dicationic complexes [Cp*M(L′)(H₂O)][X] ₂, where single water molecules are directly bonded to the metal atoms. The solid-state structures of a number of complexes were confirmed by X-ray crystallographic studies. The reaction of [Cp*Ir(L′)(H ₂O)][X]₂ with ammonium formate in water or acetone solution allows the generation of the hydride species [Cp*Ir(L′)H] [X].

Full text of DOI:10.1021/ic061928g

Inorg. Chem. 2007, 46, 896−906
Synthesis, Reactivity, Spectroscopic Characterization, X-ray Structures,
PGSE, and NOE NMR Studies of (
5-C5Me5)-Rhodium and -Iridium
Derivatives Containing Bis(pyrazolyl)alkane Ligands
η
Claudio Pettinari,*,† Riccardo Pettinari,*,† Fabio Marchetti,† Alceo Macchioni,§ Daniele Zuccaccia,§
Brian W. Skelton,‡ and Allan H. White‡
Dipartimento di Scienze Chimiche, UniVersita` di Camerino, Via S. Agostino 1, 62032 Camerino,
Italy, Dipartimento di Chimica, UniVersita` di Perugia, Via Elce di Sotto, 8-06123 Perugia, Italy,
Chemistry M313, The UniVersity of Western Australia, Crawley, Western Australia 6009, Australia
Received October 9, 2006
Rhodium(III) and iridium(III) complexes containing bis(pyrazolyl)methane ligands (pz
specifically, L1 H2C(pz)2, L2 H2C(pzMe2)2, L3 H2C(pz4Me)2, L4
Me2C(pz)2), have been prepared in a study
exploring the reactivity of these ligands toward [Cp*MCl( -Cl)]2 dimers (M Rh, Ir; Cp* pentamethylcyclopen-
tadienyl). When the reaction was carried out in acetone solution, complexes of the type [Cp*M(L )Cl]Cl were obtained.
However, when L1 and L2 ligands have been employed with excess [Cp*MCl(
-Cl)]2, the formation of [Cp*M(L )-
) pyrazole, L′ in general;
)
)
)
)
µ
)
)
′
µ
′
Cl][Cp*MCl3] species has been observed. PGSE NMR measurements have been carried out for these complexes,
in which the counterion is a cyclopentadienyl metal complex, in CD2Cl2 as a function of the concentration. The
hydrodynamic radius (rH) and, consequently, the hydrodynamic volume (VH) of all the species have been determined
from the measured translational self-diffusion coefficients (Dt), indicating the predominance of ion pairs in solution.
NOE measurements and X-ray single-crystal studies suggest that the [Cp*MCl3]- approaches the cation, orienting
the three Cl-legs of the “piano-stool” toward the CH2 moieties of the bis(pyrazolyl)methane ligands. The reaction
of 1 equiv of [Cp*M(L
the generation of [Cp*M(L
dicationic complexes [Cp*M(L
The solid-state structures of a number of complexes were confirmed by X-ray crystallographic studies. The reaction
of [Cp*Ir(L )(H2O)][X]2 with ammonium formate in water or acetone solution allows the generation of the hydride
species [Cp*Ir(L )H][X].
′
)Cl]Cl or [Cp*M(L
′
)Cl][Cp*MCl3] with 1 equiv of AgX (X
)
ClO4 or CF3SO3) in CH2Cl2 allows
′
)Cl]X, whereas the reaction of 1 equiv of [Cp*M(L′)Cl] with 2 equiv of AgX yields the
′
)(H2O)][X]2, where single water molecules are directly bonded to the metal atoms.
′
′
Introduction
are less rigid than some other bidentate ligands such as 2,2′-
bipyridine (bpy) or 1,10-phenanthroline. In addition, because
of the aromatic rings, they are likely to give more stable
adducts than the most commonly used aliphatic diamines
such as ethylenediamine. In the literature, the first rhodium-
(I) complexes containing the ligand H2C(pz)2 were reported
by Oro and co-workers.4 Rh(I) derivatives containing H2C-
(pzMe2)2 can be used as catalysts in the hydroformylation and
hydroaminomethylation of olefins.5 Ir(1,5-cyclooctadiene)
and Ir(CO)2 derivatives containing L1 and L2 have been
Since the first syntheses of poly(pyrazolyl)borates by
Trofimenko in 1966,1 over two thousand publications have
appeared describing the syntheses and applications of bis-
(pyrazolyl)borate ligands in various areas of chemistry.2
Adducts of bis(pyrazolyl)alkanes remain less studied because
of greater difficulties encountered in the preparation of large
quantities of these N2-donor species.3 These bidentate ligands
* To whom correspondence should be addressed. E-mail:
claudio.pettinari@unicam.it (C.P.); riccardo.pettinari@unicam.it (R.P.).
† Universita degli Studi di Camerino.
(3) (a) Pettinari, C.; Pettinari, R. Coord. Chem. ReV. 2005, 249, 525. (b)
Pettinari, C.; Pettinari, R. Coord. Chem. ReV. 2005, 249, 663.
(4) Oro, L. A.; Esteban, M.; Claramunt, R. M.; Elguero, J.; Foces-Foces,
C.; Hernandez, Cano, F. J. Organomet. Chem. 1984, 276, 79.
(5) Teuma, E.; Loy, M.; Le Berre, C.; Etienne, M.; Daran, J.-C.; Kalck,
P. Organometallics 2003, 22, 5261.
§ Universita` di Perugia.
‡ University of Western Australia.
(1) Trofimenko, S. J. Am. Chem. Soc. 1966, 88, 1842.
(2) Trofimenko, S. Scorpionates: The Coordination Chemistry of Poly-
pyrazolylborate Ligands; Imperial College Press: London, 1999.
896 Inorganic Chemistry, Vol. 46, No. 3, 2007
10.1021/ic061928g CCC: $37.00
© 2007 American Chemical Society
Published on Web 01/11/2007

(η5-C5Me5)-Rhodium and -Iridium DeriWatiWes
synthesized, characterized, and demonstrated to be effective
catalysts for the alcoholysis of a range of alcohols and
hydrosilanes, including secondary and tertiary hydrosilanes,
under mild conditions.6
M ) Rh, L′ ) L1; 3 M ) Ir, L′ ) L1; 5 M ) Rh, L′ ) L2;
7 M ) Ir, L′ ) L2) have been prepared from the reactions
of equimolar quantities of [Cp*MCl(µ-Cl)]2 dimers and bis-
(pyrazolyl)methane ligands L1 and L2, in THF, under N2
streams (Chart 1). The formation of the anion [Cp*MCl3]-
is rather unusual, as recently described by Severin and co-
workers, who attribute the formation of the anion in [Cp*Ru-
(C6H6)][Cp*RhCl3] to the generation of the cationic [Cp*Ru-
(C6H6)]+ moiety.19 In contrast, in our compounds, the driving
force is more likely to be the ligand conformation and the
number and nature of the substituents on the heterocyclic
ligands. Analogous [Cp*M(bpy)Cl][Cp*MCl3] bpy-contain-
ing species have not yet been reported. Under the same
conditions analogous compounds cannot be obtained by using
L3 and L4, even if a large excess of [Cp*MCl(µ-Cl)]2 is
employed. On the other hand, when L1, L2, L3, and L4 react
with [Cp*MCl(µ-Cl)]2 in acetone, [Cp*M(L′)Cl]Cl com-
plexes (2 M ) Rh, L′ ) L1; 4 M ) Ir, L′ ) L1; 6 M ) Rh,
L′ ) L2; 8 M ) Ir, L′ ) L2; 9 M ) Rh, L′ ) L3; 10 M )
Ir, L′ ) L3; 11 M ) Ir, L′ ) L4) have been prepared (Chart
1). In this solvent, no evidence of [Cp*MCl3]- formation,
as in 1, 3, 5, and 7, is found.
As an extension of our previous work on Cp*Rh(III)- and
Cp*Ir(III)-scorpionates,7 we have undertaken a systematic
study of the reactions between [Cp*MCl(µ-Cl)]2 dimers (M
) Rh, Ir) and bis(pyrazolyl)alkane (R2C)n(pz′)2 ligands.
Several studies have been reported describing the molecular
structures of [Cp*Rh(N-N)X]n+ systems, as interesting
catalytic precursors, and it has been proposed that catalytic
activity depends on the chelate ring conformation, metal-
ligand bond distances, and interbond angles. However, to
date, structural information is limited to complexes contain-
ing bipyridine-type ligands that generate five-membered
chelate rings.8
[Cp*Rh(bpy)(H2O)]2+ has been demonstrated to be a
versatile tool for efficient nonenzymatic regeneration of
oxidoreductase coenzymes such as NAD(P)H, NAD(P)+, and
FADH2.9 [Cp*Rh(bpy)H]+, generated in situ from [Cp*Rh-
(bpy)(H2O)]2+ and sodium formate,10,11 can be considered
to be a biomimetic enzymatic hydride via its ability to bind
and regioselectively transfer a hydride in the 4-ring-position
of the NAD+ model.12 Here we report the syntheses and
spectral and structural characterization of a number of
complexes containing the Cp*M synthons (M ) Rh and Ir)
with various bis(pyrazolyl)alkanes which are able to form
six-membered chelate rings. The reactivity of some species
toward PPh3 and ammonium formate has been investigated.
[Cp*Ir(L′)H]+ hydride formation has been found be inde-
pendent of the pH value and solvent employed.
Complexes 1-11 are stable both in the solid and solution
states. Under an inert atmosphere, their solutions are stable
indefinitely. IR (nujol) and NMR solution data (CDCl3) are
consistent with the η5-Cp* and κ2-L coordinations confirmed
by single-crystal X-ray studies, with a doublet in the 13C-
{1H} NMR spectra of the rhodium derivatives in the range
of 88-97 ppm (J(13C-103Rh) ≈ 8 Hz), indicative of η5-Cp*
binding. In the IR spectra, ν(M-Cl) fall between 260 and
280 cm-1, in accordance with the presence of single M-Cl
bonds. Two sets of signals in the 1H spectra, attributable to
the Cp* protons, are always detected in the spectra of 1, 3,
5, and 7, in accordance with the existence in solution of the
two ionic forms. When the 1H NMR spectra of [Cp*M(L′)-
Cl][Cp*MCl3] were measured in acetone, the immediate
formation of [Cp*M(L′)Cl]Cl was observed.
Since it is well-recognized that ion-pairing drastically
affects the reactivity and structure of ionic organometallics,13
we also considered it to be of interest to investigate the
interionic solution structures of the complexes [Cp*M(L1)Cl]+-
[Cp*MCl3]-, which possess an unusual organometallic
counterion. (By “interionic structure”, we mean both the
relative anion-cation position, determined by NOE (nuclear
Overhauser effect) NMR experiments,14-16 and the level of
aggregation, estimated by the PGSE (pulsed-field gradient
spin echo) NMR technique).17,18 This work is reported herein.
It is interesting to note that the [Cp*M(L′)Cl]Cl com-
pounds can be obtained by the reaction of [Cp*M(L′)Cl]-
[Cp*MCl3] with excess L′ (L′ ) L1 or L2, solvent ) THF)
(eq 1). On the other hand, the addition of the dimer
Results and Discussion
(14) (a) Macchioni, A. Eur. J. Inorg. Chem. 2003, 195. (b) Binotti, B.;
Macchioni, A.; Zuccaccia, C.; Zuccaccia, D. Comments Inorg. Chem.
2002, 23, 417. (c) Macchioni, A. In PerspectiVes in Organometallic
Chemistry; Screttas, C. G., Steele, B. R., Eds.; The Royal Society of
Chemistry: Cambridge, U.K., 2003; pp 196-207.
(15) (a) Beck, S.; Geyer, A.; Brintzinger, H.-H. Chem. Commun. 1999,
2477. (b) Zuccaccia, C.; Stahl, N. G.; Macchioni, A.; Chen, M.-C.;
Roberts, J. A.; Marks, T. J. J. Am. Chem. Soc. 2004, 126, 1448.
(16) Zuccaccia, D.; Sabatini, S.; Bellachioma, G.; Cardaci, G.; Clot, E.;
Macchioni, A. Inorg. Chem. 2003, 42, 5465.
(17) (a) Valentini, M.; Ru¨egger, H.; Pregosin, P. S. HelV. Chim. Acta. 2001,
84, 2833. (b) Pregosin, P. S.; Martinez-Viviente, E.; Kumar, P. G. A.
Dalton Trans. 2003, 4007. (c) Bagno, A.; Rastrelli, F.; Saielli, G. Prog.
Nucl. Magn. Reson. Spectrosc. 2005, 47, 41. (d) Brand, T.; Cabrita,
E. J.; Berger, S. Prog. Nucl. Magn. Reson. Spectrosc. 2005, 46, 159.
(e) Cohen, Y.; Avram, L.; Frish, L. Angew. Chem., Int. Ed. 2005, 44,
520. (f) Pregosin, P. S.; Kumar, P. G. A.; Ferna´ndez, I. Chem. ReV.
2005, 105, 2977.
Synthesis and Spectroscopic Characterization of Com-
plexes 1-21. The complexes [Cp*M(L′)Cl][Cp*MCl3] (1
(6) Field, L. D.; Messerle, B. A.; Rehr, M.; Soler, L. P.; Hambley, T. W.
Organometallics 2003, 22, 2387.
(7) Carmona, E.; Cingolani, A.; Marchetti, F.; Pettinari, C.; Pettinari, R.;
Skelton, B. W.; White, A. H. Organometallics 2003, 22, 2820.
(8) (a) Ogo, S.; Uehara, K.; Abura, T.; Watanabe, Y.; Fukuzumi, S. J.
Am. Chem. Soc. 2004, 126, 16520. (b) Ogo, S.; Hayashi, H.; Uehara,
K.; Fukuzumi, S. Appl. Organomet. Chem. 2005, 19, 639.
(9) Hollmann, F.; Witholt, B.; Schmid, A. H. J. Mol. Catal. B: Enzym.
2003, 19-20, 167.
(10) Kaim, W.; Reinhardt, R.; Greulich, S.; Fiedler, J. Organometallics
2003, 22, 2240.
(11) Ogo, S.; Makihara, N.; Kaneko, Y.; Watanabe, Y. Organometallics
2001, 20, 4903.
(12) Lo, H. C.; Leiva, C.; Buriez, O.; Kerr, G. B.; Olmstead, M. M.; Fish,
R. H. Inorg. Chem. 2001, 40, 6705.
(13) Macchioni, A. Chem. ReV. 2005, 105, 2039.
(18) Zuccaccia, D.; Macchioni, A. Organometallics 2005, 24, 3476.
(19) Quebatte, L.; Scopelliti, R.; Severin, K. Eur. J. Inorg. Chem. 2006,
231.
Inorganic Chemistry, Vol. 46, No. 3, 2007 897

Pettinari et al.
Chart 1
[Cp*MCl(µ-Cl)]2 to [Cp*M(L′)Cl]Cl yields [Cp*M(L′)Cl]-
[Cp*MCl3] (L′ ) L1 or L2, solvent ) THF) (eq 2)
presence of the M-Cl stretching frequency in their IR spectra
and by the characteristic absorption in the 1200-1000 cm-1
regions, attributable to an ionic SO3CF3 group.
In the 1H-NMR spectra of 1-10, 12, and 13, the bridging
geminal methylene protons (L1, L2, and L3 derivatives) are
diastereotopic and appear as two doublets arising from a well-
resolved AX system. In addition, in the spectra of 11, 14,
and 15 (L4 derivatives), the two anisochronous methyl groups
appear as two singlets.
The 1H-NOESY spectrum of complex 5 (Figure 1) shows
strong dipolar interactions between the CHup and MeCp*
protons and between CHdown and Me5 protons, with intensities
comparable to those of the interactions between Me5 (or Me3)
with H4. By contrast, no dipolar interactions are present
between the CHup and Me5 protons and between the CHdown
and MeCp* protons. These observations are consistent with
the preferential presence in solution of the boat conformer
shown in Figure 1. In this conformation, the pyrazolyl rings
[Cp*M(L′)Cl][Cp*MCl3] + L f 2[Cp*M(L′)Cl]Cl (1)
[Cp*M(L′)Cl]Cl + 1/2[Cp*MCl(µ-Cl)]2 f
[Cp*M(L′)Cl][Cp*MCl3] (2)
Compounds 12-15 [Cp*M(L′)Cl][CF3SO3] (12 M ) Rh,
L′ ) L1; 13 M ) Rh, L′ ) L2; 14 M ) Rh, L′ ) L4; 15 M
) Ir, L′ ) L4) have been prepared in one-pot syntheses by
mixing equimolar quantities of the [Cp*MCl(µ-Cl)]2 dimers
and the N2-donor ligand L4, followed by the addition of the
silver salt. Compounds 12-15 can also be prepared by the
reaction between equimolar quantities of the [Cp*M(L′)Cl]-
Cl species and silver triflate. These species, which are air
and solution stable, are readily soluble in polar solvents. The
substitution of only one chloride group is supported by the
898 Inorganic Chemistry, Vol. 46, No. 3, 2007

(η5-C5Me5)-Rhodium and -Iridium DeriWatiWes
Figure 2. 1H NMR spectrum (D2O solution) of a mixture of 19 and
HCOONH4 in 1:3 molar ratio at 296 K (pH ≈ 7).
perature as sharp singlets, suggesting that the inversion of
the metal center for the dicationic water complexes is fast
on the NMR scale, in accordance with the literature.23
However, when the acetone solutions of 16 and 20 are cooled
down to 210 K, two doublets from the resolved AB system
appear, whereas in the case of 18 and 19, two sharp signals
are evident at 253 Κ. No change has been observed until
213 K.
We have also observed that compounds 17 and 19, soluble
in water, react with ammonium formate, in the absence of
reducible substrates, in water or acetone solution indiffer-
ently, yielding the hydride complex [Cp*Ir(L′)H]+ (Figure
2), presumably through a â-hydrogen elimination with
evolution of CO2, in accordance with the literature.11,12 It is
interesting to note that in our case hydride generation occurs
in the pH range of 3-7, independently of the solvent choice,
whereas the amount of hydride formation depends on the
ligand choice, the higher quantity being formed when the
L4 derivative 19 is employed.
1
Figure 1. Section of H-NOESY NMR spectrum (400.13 MHz, 296 K,
CD2Cl2, mixing time ) 800 ms) of complex 5. On the top, the two boat
and chair conformations of the metallacycle M(N-N)2C are depicted with
the expected NOEs between CHup (and CHdown) and Me5 (and MeCp*). The
asterisk (*) denotes the resonance of H2O.
When 13 reacts with an equimolar quantity of PPh3,
displacement of the chloride ligand from the Rh coordination
sphere is observed, with the formation of the dicationic
[Cp*Rh(L2)PPh3][Cl][SO3CF3] compound 21. The 31P NMR
spectrum of 21 indicates coordination in solution of the P
donor, the Rh-P coupling constant being similar to those
reported for analogous Rh(III) species.24
NOE and PGSE NMR Measurements. The interionic
structures in solutions of compounds 5 and 13 were studied
by combining the information derived from NOE (nuclear
Overhauser effect)25 and PGSE (pulsed-field gradient spin-
echo)26 NMR experiments.
are positioned far away from the encumbered Cp*. The same
conformation of the metallacycle M(N-N)2C is observed
in the solid state for all complexes studied.
Upon warming of methanol or chloroform solutions of
complexes 1-15 to 331 K, no changes were observed in
1
the H-NMR spectra, suggesting that they are very rigid
molecules20,21 in which the inversion of the metal center is
very slow on the NMR scale.22
Finally, compounds 16-19, [Cp*M(L′)(H2O)][CF3SO3]2
(16 M ) Rh, L′ ) L1; 17 M ) Ir, L′ ) L2; 18 M ) Rh, L′
) L4; 19 M ) Ir, L′ ) L4), which contain two triflate ions
and one water molecule bonded to the Cp*M moiety
(confirmed by X-ray and IR data), can be obtained in two
different ways: (i) by mixing 1 equiv of [Cp*MCl(µ-Cl)]2
with 2 equiv of N2-donor ligands and 4 equiv of the silver
salt and (ii) by the reaction of compounds 12, 14, and 15
with excess of the silver triflate. The presence of adventitious
water can be attributed to the not rigorously anhydrous
solvents employed for the recrystallization of 16-19.
Compound 20 has been prepared with the same procedure
reported for 16-19, but with silver(I) perchlorate.
The relative anion-cation orientations in solution for
complexes 5 and 13 ([Cp*Rh(L2)Cl][X]) were investigated
-
by recording 19F,1H-HOESY (X- ) CF3SO3 ) and 1H-
NOESY (X- ) [Cp*RhCl3]-) NMR spectra at room tem-
perature (296 K) in CD2Cl2.
For complex 13, strong interionic NOE contacts were
-
observed between the fluorine atoms of CF3SO3 and the
(23) (a) Asano, H.; Katayama, K.; Kurosawa, H. Inorg. Chem. 1996, 35,
5760. (b) Davies, D. L.; Fawcett, J.; Garratt, S. A.; Russell, D. R.
Organometallics 2001, 20, 3029.
It is interesting to note that in 16 and 18-20, the CH3 or
CH2 protons of the methylene chain appear at room tem-
(24) Pettinari, C.; Marchetti, F.; Pettinari, R.; Pizzabiocca, A.; Drozdov,
A.; Troyanov, S. I.; Vertlib, V. J. Organomet. Chem. 2003, 688, 216.
(25) Neuhaus, D.; Williamson, M. The Nuclear OVerhauser Effect in
Structural and Conformational Analysis, 2nd ed; WILEY-VCH:
Chichester, U.K., 2000.
(26) (a) Hahn, E. L. Phys. ReV. 1950, 80, 580. (b) Stejskal, E. O; Tanner,
J. E. J. Chem. Phys. 1965, 42, 288. (c) Stilbs, P. Prog. Nucl. Magn.
Reson. Spectrosc. 1987, 19, 1. (d) Price, W. S. Concepts Magn. Res.
1997, 9, 299. (e) Price, W. S. Concepts Magn. Reson. 1998, 10, 197.
(f) Johnson, C. S., Jr. Prog. Nucl. Magn. Res. Spectrosc. 1999, 34,
203.
(20) Minghetti, G.; Cinellu, M. A.; Bandini, A. L.; Banditelli, G.; Demartin,
F.; Manassero, M. J. Organomet. Chem. 1986, 315, 387.
(21) Cinellu, M. A.; Stoccoro, S.; Minghetti, G, Bandini, A. L.; Banditelli,
G.; Bovio, B. J. Organomet. Chem. 1989, 372, 311.
(22) (a) Brunner, H. Angew. Chem. 1999, 111, 1248. (b) Brunner, H.;
Zwack, T. Organometallics 2000, 19, 2423. (c) Brunner, H. Eur. J.
Inorg. Chem. 2001, 905.
Inorganic Chemistry, Vol. 46, No. 3, 2007 899

Pettinari et al.
Table 1. Diffusion Coefficients (Dt, ×1010 m2 s-1), Hydrodynamic
Radii (rH, Å), Hydrodynamic Volumes (VH, Å3), and Aggregation
Numbers (N) for Compounds 5 and 13 in CD2Cl2 as a Function of
Concentration (C, mM)
+
-
+
-
entry
Dt+
Dt-
rH
rH
VH
VH
N+ N-
C
5
1
2
3
4
5
6
10.7 11.0 5.2
10.6 10.6 5.3
9.6 10.3 5.6
5.0
5.3
5.3
5.4
5.4
5.5
575
600
720
720
755
771
533 1.0 0.9
600 1.0 1.0
610 1.2 1.0
649 1.2 1.1
670 1.3 1.1
0.008
0.1
1.4
4.2
8.5
9.3
9.0
8.5
9.7 5.6
9.5 5.7
9.0 5.7
694 1.3 1.2 31
13
7
8
9
10
11
10.7 12.7 5.0
10.3 11.3 5.3
10.1 10.2 5.4
9.8 10.2 5.5
9.6 10.0 5.5
4.4
4.9
5.3
5.3
5.3
540
627
652
681
674
364 1.2 0.8
502 1.4 1.1
630 1.5 1.4
623 1.6 1.4
0.05
0.6
3.5
7.2
616 1.6 1.4 30.0
to lie in the range of 3.3-3.7 Å and indicate the presence of
electrostatic C-Hδ+‚‚‚Clδ- interactions29 (cf. the X-ray work,
below). For complex 5, containing the [Cp*RhCl3]- coun-
1
terion, the H-NOESY NMR spectrum does not show any
interionic dipolar interactions between the MeCp* resonance
of the anion and the cationic protons. This suggests that the
[Cp*RhCl3]- species approaches the cation orienting the
three Cl legs of the “piano-stool” toward the cation and,
plausibly, toward the CH2-moiety of the cation where the
positive charge is mainly accumulated.27,28 Again, this
orientation is consistent with that found in the solid state
where the organometallic anion that is closest to the cation
orients the three chlorines toward the methylene carbon
(Figure 4). The distances between the chlorine legs and the
methylene carbons are in the range of 3.3-4.0 Å, establishing
in this case also the C-Hδ+‚‚‚Clδ- interaction.
Figure 3. Section of 19F-1H-HOESY NMR spectrum (400.13 MHz, 296
K, CD2Cl2, mixing time ) 800 ms) of complex 13. The asterisk (*) denotes
the resonance due to a residue of non-deuterated solvent.
Me5 protons (Figure 3). Medium-sized NOEs were also
detected with the MeCp* resonance, while weak NOEs were
observed with the CH2 resonance. The anion did not show
any interaction with Me3 and H4. All these observations
indicate that the CF3SO3- group lies close to the CH2 moiety,
between the two methyl groups in position 5 (Figure 3), as
previously observed for octahedral Ru(II)27 and square-planar
Pd(II) and Pt(II)28 complexes. In this position, the anion also
has a dipolar interaction with the methyl groups of Cp*
(Figure 3).
1H- and 19F-PGSE NMR experiments were carried out for
complexes 5 and 13 in CD2Cl2 using TMSS as internal
standard (TMSS ) [tetrakis-(trimethylsilyl)silane]). PGSE
measurements allowed the translational self-diffusion coef-
ficients (Dt) for both cationic (Dt+) and anionic (Dt-) moieties
(Table 1) to be determined. By applying (see the Experi-
mental Section) the Stokes-Einstein equation Dt ) kT/
cπηrH, where k is the Boltzman constant, T is the temper-
ature, c is a numerical factor,18 and η is the solution viscosity,
the average hydrodynamic radii for the anionic (rH+) and
cationic (rH-) moieties were measured (Table 1). Their
hydrodynamic volumes (VH) were obtained from rH, assum-
ing the aggregates to have a spherical shape. From the ratio
between VH and the Van der Waals (VVdW) volumes of the
ion pairs, known from the solid state (Experimental Section),
the cationic (N+) and anionic (N-) aggregation numbers were
evaluated (Table 1). Because, a distribution of ionic species
is present in solution, N+ and N- indicate the apparent
average aggregation number of the ionic moieties. For
example, if they are both equal to 1 or 2, this means that
either ion pairs or ion quadruples, that is, (Ru+X-)2, are the
predominant species in solution, respectively. On the other
hand, if N+, N-, or both are lower than 1, then free ions are
This single cation-anion orientation in solution deduced
by NOE studies is consistent with that in the solid state.
X-ray investigations of complexes containing Cl- as coun-
terion indicate that the cation lies close to two anions in the
solid state (see below). Both anions are adjacent to the bis-
(pyrazolyl)methane ligands, near to the CH2-moiety and well
removed from the chlorine ligand. The distances between
the chloride anions and the methylene carbons are calculated
(27) (a) Bellachioma, G.; Cardaci, G.; Macchioni, A.; Reichenbach, G.;
Terenzi, S. Organometallics 1996, 15, 4349. (b) Macchioni, A.;
Bellachioma, G.; Cardaci, G.; Gramlich, V.; Ru¨egger, H.; Terenzi,
S.; Venanzi, L. M. Organometallics 1997, 16, 2139. (c) Macchioni,
A.; Bellachioma, G.; Cardaci, G.; Cruciani, G.; Foresti, E.; Sabatino,
P.; Zuccaccia, C. Organometallics 1998, 17, 5549. (d) Zuccaccia, C.;
Bellachioma, G.; Cardaci, G.; Macchioni, A. J. Am. Chem. Soc. 2001,
123, 11020.
(29) (a) Steiner, T. Angew. Chem., Int. Ed. 2002, 41, 48. (b) Jeffrey, G. A.
An Introduction to Hydrogen Bonding; Oxford University Press:
Oxford, U.K., 1997.
(28) Binotti, B.; Bellachioma, G.; Cardaci, G.; Macchioni, A.; Zuccaccia,
C.; Foresti, E.; Sabatino, P. Organometallics. 2002, 21, 346.
900 Inorganic Chemistry, Vol. 46, No. 3, 2007

(η5-C5Me5)-Rhodium and -Iridium DeriWatiWes
Figure 4. Anion-cation orientations in the solid state for compound 7 (Projection quasi-normal to the crystallographic mirror plane).
Table 2. Metal Atom Environments (bond distances, Å, and angles, deg)
atom/M/X
4/Ir/Cl
6‚2H2O/Rh/Cl
15/Ir/Cl
16/Rh/OH2
18/Rh/OH2
M-N(12)
2.053(7)
2.073(7)
2.108(8)
-2.172(8)
2.14(2)
2.131(2)
2.124(2)
2.155(2)
-2.176(2)
2.167(9)
1.784
2.083(5)
2.083(6)
2.138(7)
-2.168(8)
2.153(11)
1.779
2.115(2)
2.118(1)
2.127(2)
-2.172(2)
2.15(2)
2.118(4)
2.114(3)
2.138(4)
-2.159(3)
2.150(9)
1.768
M-N(22)
M-Ar(cp)
M-Ar(0)
M-X
1.769
2.383(2)
1.763
2.185(1)
2.4136(6)
2.401(2)
2.172(3)
X-M-N(12)
85.9(2)
87.0(2)
128.4
82.9(3)
126.9
87.57(4)
87.86(6)
124.5
86.49(7)
128.5
83.8(2)
84.2(2)
123.6
86.1(2)
131.8
83.88(5)
81.54(5)
129.2
87.31(5)
129.1
81.0(1)
81.7(1)
127.7
86.3(1)
131.5
X-M-N(22)
X-M-Ar(0)
N(12)-M-N(22)
N(12)-M-Ar(0)
N(22)-M-Ar(0)
130.3
128.4
130.9
129.3
130.6
present in solution. If only free ions were present in solution,
N+ and N- should be 0.60 and 0.40 for 5 and 0.84 and 0.16
for 13. PGSE NMR data reported in Table 1 clearly indicate
that complexes 5 and 13 are mainly present in CD2Cl2 as
ion pairs even at micromolar concentration (entries 1 and
7). These findings suggest that, in addition to the electrostatic
forces, specific C-Hδ+‚‚‚Xδ- (X ) O for complex 13 and
Cl for complex 5) interactions occur in solution as previously
described.28 In addition, an increase of the salt concentra-
tion causes further aggregation with the formation of
aggregates higher than that of ion pairs (entries 6 and
9-11);16 the tendency seems less in compound 5, compared
to compound 13.
Crystal Structures. A number of the present molecular
geometries for all complexes studied, except 5, 7, and the
dichloromethane solvate of 6 (which, for the cations, may
be regarded as represented by more precisely determined
similar (or identical) species), are presented in Table 3. In
5, in the [Cp*RhCl3]- counterion, which, like the cation, lies
on a crystallographic mirror plane, Rh-Cl distances are
2.421(4) and 2.428(3) (×2) Å with the Rh-Cp (centroid)
being 1.765 Å; the Cp (centroid)-Rh-Cl angles range
between 121.73(7) and 126.3(1)°, with Cl-Rh-Cl being
90.0(1) (×2) and 92.8(1)°, harmonious with the values of
ref 19. In 7, in the anion, the Ir-Cl distances are 2.427(6)
and 2.427(5) (×2) Å, with Ir-Cp (centroid) being 1.763 Å;
the Cp (centroid)-Ir-Cl angles range between 125.75(9)
and 127.5(2)° with Cl-Ir-Cl being 89.4(2) and 87.8(2)°
(×2). For the most precisely determined [Cp*M(L′)Cl]+
cations of 6 and 15, the values of Table 3 differ little from
those of the neutral counterpart molecules of the scorpionates
of ref 7; in 16 and 18, where the X ligand is aqua, the
exchange appears to have little impact on the remainder of
the coordination environment. In 16, in particular, there are
interesting hydrogen-bonding interactions with the oxygen
atoms of the triflate anions (Figure 5).
In 4, 6‚2H2O, 15, 16, and 18‚3H2O, a single formula unit,
devoid of crystallographic symmetry, comprises the asym-
metric unit of the structure. In 4, with water molecule
hydrogen atoms postulated from difference map evidence,
we find that in projection down a, as set, the anions and
solvent molecules comprise a well-defined ribbon down the
center of the cell (Cl(2)‚‚‚O(1), H(1a); O(1), H(1a)(xj, yj, jz)
3.170(7), 2.7 (est (estimated); 3.216(7), 2.7 Å (est)) bounded
by columns of cations. There are contacts to the CH2
hydrogen atoms of the L′ ligands (Cl(2)‚‚‚C(0), H(0a),
H(0b) (xj, yj, jz) 3.565(9), 2.7 Å (×2)), although there are
stronger interactions to either side with the pyrazole ring
hydrogen atoms. Compounds 5 and 7 are “isomorphous”,
with “disorder” being resolvable in the former but not the
latter. Cations and anions approach each other pairwise as
depicted in Figure 4; for 7, the Cl3 component of the anion
embraces the CH2 bridge of the cation. In the better-defined
Ir complex, 7, C(10), H(101,102)‚‚‚Cl(22) are 3.35(2), 3.0,
Inorganic Chemistry, Vol. 46, No. 3, 2007 901

Pettinari et al.
Table 3. Crystal/refinement Data
4‚H2Oa
5
6‚2H2Ob
6‚1/2CH2Cl2
7
15
18‚3H2O
16*
formula
Mr (Da)
cryst syst
C
564.6
triclinic
17H25Cl2IrN4O C31H46Cl4N4Rh2
C
549.3
monoclinic
P21/n
(No. 14)
15.765(2)
8.3050(10)
18.554(2)
90.261(9)
2429
100
1.502
4
0.95
21H35Cl2N4O2Rh C21.5H32Cl3N4Rh C31H46Cl4Ir2N4
C
688.2
monoclinic
C2/c
(No. 15)
22.596(5)
8.570(2)
23.910(5)
91.232(4)
4624
153
1.977
8
6.0
20H27ClF3IrN4O3 C21H35F6N4O10RhS2 C19H25F6N4O7RhS2
822.4
555.8
triclinic
P1h
1000.9
monoclinic
P21/m
(No. 11)
9.6379(8)
14.1369(9))
14.047(2)
110.073(8)
1798
784.6
702.5
monoclinic
P21/m
(No. 11)
9.623(3)
14.176(4)
13.315(4)
99.136(5)
1793
153
1.244
2
1.24
monoclinic
P21/n
monoclinic
Cc
space group P1h
(No. 2)
7.542(3)
8.536(3
15.912(6)
99.460(6)
972.8
153
1.927
2
7.2
(No. 2)
(No. 14)
11.184(3)
23.044(6)
13.132(3)
113.902(4)
3094
(No. 19)
18.293(3)
10.2940(10)
14.626(4)
105.891(7)
2649
a (Å)
b (Å)
c (Å)
12.602(4)
13.993(5)
17.467(6)
82.048(5)
2652
â (deg)
V (Å3)
T (K)
Dc (g cm-3
Z
153
100
153
100
)
1.392
4
1.849
2
1.684
1.761
4
4
µ
Mo (mm-1
)
0.91
7.7
0.78
0.89
specimen
(mm3)
Tmin/max
Nt
2θmax (deg)
N
0.07 × 0.05
× 0.03
0.57
8815
55
4298
0.052
0.35 × 0.25
× 0.03
0.60
16 722
52.5
3782
0.096
2516
0.10
0.12
1.13
0.38 × 0.24
× 0.12
0.85
71 975
70
10 706
0.036
8169
0.28 × 0.17
× 0.06
0.57
22 725
50
9126
0.075
9126
0.28 × 0.21
× 0.055
0.37
9406
50
3265
0.071
2635
0.084
0.08 × 0.07
× 0.03
0.58
21 808
52.5
4690
0.064
3385
0.060
0.093
1.14
0.24 × 0.13
× 0.12
0.85
28 712
58
7818
0.045
6128
0.043
0.12
1.09
0.28 × 0.26
× 0.19
0.93
44 821
76
13 535
0.030
11410
0.034
Rint
No (I > 2σ(I)) 4298
R1
wR2
GOF
0.052
0.12
1.14
0.037
0.103
1.10
0.10
0.12
1.17
0.22
1.09
0.060
1.010
b
a R, γ ) 102.563(6), 97.057(6)°. R, γ ) 74.662(5), 63.242(5)°.
2.9 Å (est). Compound 6 is described in two phases. In the
better defined form, modeled as a dihydrate, the anions and
solvent molecules are modeled with a considerable degree
of disorder, forming a ribbon, seen at the center of the cell
in projection down b contained to either side by the planes
of the Cp* ligands, the bridging CH group of the cation
interacting with the chloride of an adjacent cation
(Cl(1)‚‚‚C(10), H(10B) (x, 1 + y, z) 3.659(3), 2.7 Å (est).
In the other phase, modeled as a dichloromethane hemisol-
vate, two ion pairs plus a disordered solvent molecule make
up the asymmetric unit of the structure; one of the anions
(Cl(01/03), is also disordered. Contacts are found from C(10),
H(10B) of cation 1 to Cl(01) ( xj, 1 - y, jz) 3.711(9), 2.8
(est) and from C(10), H(10A) to component Cl(02) (1 + x,
y, z) (3.30(1), 2.7 Å (est)), the CH2 group of cation 2
interacting more strongly with a solvent fragment.
the two triflate anions, one linking the residues into a
polymer.
Experimental Section
Materials and Methods. All chemicals and reagents were of
reagent grade quality and were used as received without further
purification. All solvents were distilled prior to use. THF and light
petroleum (310-333 K) were dried by refluxing over freshly cut
sodium. Dichloromethane was freshly distilled from CaH2. Other
solvents were dried and purified by standard procedures. The
samples were dried in vacuo to constant weight (293 K, 0.1 Torr).
Elemental analyses were carried out in-house with a Fisons
Instruments 1108 CHNSO-elemental analyzer. IR spectra from 4000
to 150 cm-1 were recorded with a Perkin-Elmer System 2000 FT-
IR instrument. 1H and 13C{1H} NMR solution spectra were recorded
1
on a VXR-300 Varian spectrometer (300 for H and 75 MHz for
13C, respectively). One- and two-dimensional 1H, 13C, 19F, and 31
P
NMR spectra were measured on Bruker DRX 400 spectrometers.
Referencing is relative to TMS (1H and 13C), CCl3F(19F), and 85%
H3PO4 (31P). NMR samples were prepared by dissolving a suitable
amount of compound in 0.5 mL of solvent.
In 15, where the anion is triflate, the closest interactions
arise from the oxygen atoms to peripheral pyrazole hydrogen
atoms: O(11)‚‚‚C, H(23) (1/2 + x, 1/2 + y, z) 3.20(1), 2.3
(est); O(12)‚‚‚C, H(25) (1/2 - x, 1/2 + y, jz) 3.05(1), 2.2 Å
(est). In 16 and 18, unsurprisingly, the coordinated water
molecules are found to interact strongly with the anions,
triflates in both cases. In 16, as noted above, these are
straightforward (Figure 5): O(1), H(1B)‚‚‚O(11) 2.689(2),
1.8 (est); O(1), H(1A)‚‚‚O(22) 2.715(2), 1.8 Å (est)). In 18
(which is hydrated), a more extended network is found, the
hydrogen atoms of the coordinated water molecule hydro-
gen bonding to other uncoordinated water molecule oxy-
gen atoms: O(1), H(1a)‚‚‚O(2) 2.658(5), 1.7 (est); O(1),
H(1b)‚‚‚O(3) 2.658(6), 1.8 Å (est). The hydrogen atoms of
the latter (O(2,3)) in turn then hydrogen bond further afield,
one to a residue assigned as a water molecule oxygen atom
O(4) (for which no hydrogen atoms were located, although
plausible interactions could be postulated with triflate oxygen
atoms: O(4)‚‚‚O(21), O(21) ( xj, yj, jz) 2.88(1) (×2) Å) and
Syntheses. [Cp*Rh(L1)Cl][Cp*RhCl3] (1). A THF solution
containing [Cp*RhCl(µ-Cl)]2 (0.182 g, 0.294 mmol) and L1 (0.087
g, 0.588 mmol) was stirred for 48 h under N2 at room temperature.
The resulting orange precipitate was isolated by filtration and dried
in vacuum. The residue obtained was washed with 5 mL of THF
and recrystallized from 1:1 CH2Cl2/light petroleum (40-60 °C) and
shown to be compound 1 (0.200 g, 0.261 mmol, yield 89%). mp:
208-210 °C. Anal. Calcd for C27H38Cl4Rh2N4: C, 42.32; H, 5.00;
N, 7.31. Found: C, 41.96; H, 4.92; N, 7.27. IR (nujol, cm-1):
3098w, 1768w, 1631s, 1508w ν(C-C, C-N), 450w, 398w, 277s
1
ν(Rh-Cl). H NMR (CD3OD, 293 K): δ 1.57 (s, 15H, CH3Cp*),
2
1.64 (s, 15H, CH3Cp*), 6.26, 6.87 (d, 2Hgem, CH2(pz)2, J ) 14.3
Hz), 7.28 (s, 2H, H4), 7.48 (d, 2H, H5), 9.37 (s, 2H, H3). 1H NMR
(DMSO, 293 K): δ 1.50 (s, 15H, CH3Cp*), 1.63 (s, 15H, CH3Cp*),
2
6.26, 6.68 (d, 2H, CH2, Jgem ) 14.3 Hz), 7.15 (s, 2H, H4), 7.63
(d, 2H, H5), 9.78 (s, 2H, H3). 13C NMR (CD3OD, 293 K): δ, 8.74
(s, CH3Cp*), 8.90 (s, CH3Cp*), 57.61 (s, CH2), 94.60 (dbr, CCp*),
902 Inorganic Chemistry, Vol. 46, No. 3, 2007

(η5-C5Me5)-Rhodium and -Iridium DeriWatiWes
that reported for 1 using [Cp*IrCl(µ-Cl)]2 and L1. mp: 258-260
°C. Anal. Calcd for C27H38Cl4N4Ir2: C, 34.32; H, 4.05; N, 5.93.
Found: C, 34.26; H, 4.24; N, 5.82. IR (nujol, cm-1): 3114w,
1
1515w, ν(C-C, C-N), 279s ν(Ir-Cl). H NMR (CDCl3, 293
K): δ 1.66 (s, 15H, CH3Cp*), 1.71 (s, 15H, CH3Cp*), 5.68, 9.05 (d,
2
2H, CH2, Jgem ) 14.0 Hz), 6.46 (t, 2H, H4), 7.64 (d, 2H, H5),
9.37 (d, 2H, H3). 13C NMR (CDCl3, 293 K): δ 9.18 (s, CH3Cp*),
9.41 (s, CH3Cp*), 63.22 (s, CH2), 88.92 (s, CCp*), 108.80 (s, C4),
136.40 (s, C5), 144.35 (s, C3).
[Cp*Ir(L1)Cl][Cl]‚H2O (4). Compound 4 (0.112 g, 0.198 mmol,
yield 67%) was prepared following a procedure similar to that
reported for 2 using [Cp*IrCl(µ-Cl)]2 and L1. mp: 214-215 °C.
Anal. Calcd for C17H25Cl2IrN4O: C, 36.17; H, 4.46; N, 9.92.
Found: C, 35.75; H, 4.48; N, 9.65. IR (nujol, cm-1): 3400br,
3111w, 1514 m, ν(C-C, C-N), 275s ν(Ir-Cl). 1H NMR
(CD3OD, 293 K): δ 1.71 (s, 15H, CH3Cp*), 5.88, 7.03 (d, 2H, CH2,
2Jgem ) 14.6 Hz), 6.65 (t, 2H, H4), 7.88 (d, 2H, H5), 8.15 (d, 2H,
1
H3). H NMR (CDCl3, 293 K): δ 1.70 (s, 15H, CH3Cp*), 5.77,
9.07 (d, 2H, CH2, 2Jgem ) 14.6 Hz), 6.48 (t, 2H, H4), 7.65 (d, 2H,
H5), 8.71 (d, 2H, H3). 13C NMR (CD3OD, 293 K): δ 9.18 (s,
CH3Cp*), 64.31 (s, CH2), 90.71 (s, CCp*), 110.13 (s, C4), 135.92 (s,
C5), 147.06 (s, C3). 13C NMR (CDCl3, 293 K): δ 9.38 (s, CH3Cp*),
62.89 (s, CH2),88.95 (s, CCp*), 108.85 (s, C4), 136.29 (s, C5), 144.49
(s, C3).
[Cp*Rh(L2)Cl][Cp*RhCl3] (5). Compound 5 (0.210 g, 0.279
mmol, yield 87%) was prepared following a procedure similar to
that reported for 1 using [Cp*RhCl(µ-Cl)]2 and L2. mp: 280-281
°C. Anal. Calcd for C31H46Cl4N4Rh2: C, 43.41; H, 5.41; N, 6.53.
Found: C, 43.30; H, 5.31; N, 6.60. IR (nujol, cm-1): 3400br, 1556s,
ν(C-C, C-N), 279s ν(Rh-Cl). 1H NMR (CDCl3, 293 K): δ 1.63
(s, 15H, CH3Cp*), 1.76 (s, 15H, CH3Cp*), 2.41 (s, 6H, 5-CH3), 2.62
(s, 6H, 3-CH3), 6.09, 7.06 (d, 2H, CH2, 2Jgem ) 14.3 Hz), 5.99 (s,
2H, H4). 13C NMR (CDCl3, 293 K): δ 9.56 (s, CH3Cp*), 10.12 (s,
CH3Cp*), 12.54 (s, 5-CH3), 15.12 (s, 3-CH3), 59.77 (s, CH2), 94.10
(dbr, CCp*), 97.03 (d, CCp*, J(103Rh-13C) ) 7.8 Hz), 109.16 (s, C4),
144.61 (s, C5), 154.36 (s, C3).
[Cp*Rh(L2)Cl][Cl]‚2H2O (6). Compound 6 (0.122 g, 0.222
mmol, yield 75%) was prepared following a procedure similar to
that reported for 2 using [Cp*RhCl(µ-Cl)]2 and L2. mp: 281-283
°C. Anal. Calcd for C21H35Cl2N4O2Rh: C, 45.92; H, 6.42; N, 10.20.
Found: C, 45.64; H, 6.64; N, 10.24. IR (nujol, cm-1): 3400sbr,
1560 m, 1531w, 1519w ν(C-C, C-N), 274s ν(Rh-Cl). 1H NMR
(CDCl3, 293 K): δ 1.73 (s, 15H, CH3Cp*), 2.38 (s, 6H, 5-CH3),
Figure 5. Projections of individual molecules (ions) of (a) 6a and (b) 16.
97.30 (d, CCp*, J(103Rh-13C) ) 8.5 Hz), 121.36(s, C4), 131.81 (s,
C5), 140.84 (s, C3).
2
2.58 (s, 6H, 3-CH3), 6.06, 7.04 (d, 2H, CH2, Jgem ) 16.6 Hz),
5.98 (s, 2H, H4). 13C NMR (CDCl3, 293 K): δ 9.56 (s, CH3Cp*),
[Cp*Rh(L1)Cl][Cl]‚H2O (2). An acetone solution (10 mL)
containing [Cp*RhCl(µ-Cl)]2 (0.182 g, 0.294 mmol) and L1 (0.087
g, 0.588 mmol) was stirred for 6 h under N2 at room temperature.
The resulting orange precipitate was isolated by filtration and dried
in vacuum. The residue obtained was washed with 5 mL of acetone
and recrystallized from 1:1 CH2Cl2/light petroleum (40-60 °C) and
shown to be compound 2 (0.095 g, 68% yield). mp: 217-219 °C.
Anal. Calcd for C17H25Cl2N4ORh: C, 42.32; H, 5.39; N, 11.00.
Found: C, 42.69; H, 5.30; N, 11.19. IR (nujol, cm-1): 3380wbr,
12.52 (s, 5-CH3), 15.24 (s, 3-CH3), 59.77 (s, CH2), 96.97 (d, CCp*
,
J(103Rh-13C) ) 8.3 Hz), 109.16 (s, C4), 144.61 (s, C5), 154.36 (s,
C3).
[Cp*Ir(L2)Cl][Cp*IrCl3] (7). Compound 7 (0.224 g, 0.223
mmol, yield 76%) was prepared following a procedure similar to
that reported for 1 using [Cp*IrCl(µ-Cl)]2 and L2. mp: 105-106.
°C. Anal. Calcd for C31H46Cl4N4Ir2: C, 35.93; H, 4.47; N, 5.41.
Found: C, 36.29; H, 4.76; N, 5.53. IR (nujol, cm-1): 3400br, 1556s,
ν(C-C, C-N), 278s ν(Ir-Cl). 1H NMR (CDCl3, 293 K): δ 1.62
(s, 15H, CH3Cp*), 1.71 (s, 15H, CH3Cp*), 2.41 (s, 6H, 5-CH3), 2.71
(s, 6H, 3-CH3), 5.88, 7.20 (d, 2H, CH2, 2Jgem ) 16.6 Hz), 6.05 (s,
2H, H4). 13C NMR (CDCl3, 293 K): δ 9.07 (s, CH3Cp*), 9.83 (s,
CH3Cp*), 12.58 (s, 5-CH3), 15.04 (s, 5-CH3), 61.90 (s, CH2), 96.20
(s, CCp*), 88.83 (s, CCp*), 109.01 (s, C4), 144.25 (s, C5), 154.03 (s,
C3).
1
1530w, 1507w ν(C-C, C-N), 274s ν(Rh-Cl). H NMR (CD3-
OD, 293 K): δ 1.74 (s, 15H, CH3Cp*), 6.06, 6.98 (d, 2Hgem, CH2,
2Jgem ) 14.7 Hz), 6.62 (t, 2H, H4), 7.92 (d, 2H, H5), 8.17 (d, 2H,
1
H3). H NMR (CD3OD, 331K): δ 1.74 (s, 15H, CH3Cp*), 6.06,
6.98 (d, 2H, CH2, 2Jgem ) 14.7 Hz), 6.59 (t, 2H, H4), 7.89 (d, 2H,
H5), 8.14 (d, 2H, H3). 13C NMR (CDCl3, 293 K): δ 9.70 (s,
CH3Cp*), 64.38 (s, CH2), 97.04 (d, CCp*, J(103Rh-13C) ) 8.5 Hz),
108.45 (s, C4), 137.20 (s, C5), 144.29 (s, C3).
[Cp*Ir(L2)Cl][Cl]‚2H2O (8). Compound 8 (0.160 g, 0.250
mmol, yield 85%) was prepared following a procedure similar to
that reported for 2 using [Cp*IrCl(µ-Cl)]2 and L2. mp: 107-108
[Cp*Ir(L1)Cl][Cp*IrCl3] (3). Compound 3 (0.236 g, 0.249
mmol, yield 85%) was prepared following a procedure similar to
Inorganic Chemistry, Vol. 46, No. 3, 2007 903

Pettinari et al.
°C (dec). Anal. Calcd for C21H35N4Cl2O2Ir: C, 39.49; H, 5.52; N,
8.77. Found: C, 39.60; H, 5.50; N, 8.45. IR (nujol, cm-1): 3390br
ν(O-H, H2O), 3121w, 3083w ν(C-H), 1620br, 1556s ν(C-C,
C-N), 1281s, 1029s, 453w, 362w, 278s ν(Ir-Cl). 1H NMR
(CDCl3, 293 K): δ 1.70 (s, 15H, CH3Cp*), 2.40 (s, 6H, 5-CH3),
2.67(s, 6H, 3-CH3), 5.90, 7.20 (d, 2H, CH2, 2Jgem ) 16.5 Hz), 6.05
(s, 2H, H4). 13C NMR (CDCl3, 293 K): δ 9.83 (s, CH3Cp*), 12.58
(s, 5-CH3), 15.05 (s, 3-CH3), 61.90 (s, CH2), 88.83 (s, CCp*), 109.02
(s, C4), 144.26 (s, C5), 154.04 (s, C3).
(CDCl3, 293 K): δ 9.25 (s, CH3Cp*), 62.77 (s, CH2), 97.03 (d, CCp*,
J(103Rh-13C) ) 8.2 Hz), 108.92 (s, C4), 135.57 (s, C5), 145.64 (s,
C3).
[Cp*Rh(L2)Cl][CF3SO3] (13). Compound 13 (0.262 g, 0.442
mmol, yield 75%) was prepared following a procedure similar to
that reported for 12 using [Cp*RhCl(µ-Cl)]2, L2, and AgCF3SO3.
Anal. Calcd for C22H31F3N4O3RhS: C, 44.68; H, 5.28; N, 9.47.
Found: C, 44.60; H, 5.14; N, 9.22. IR (nujol, cm-1): 3535br
ν(H2O), 3114s ν(CF3SO3), 1560 m, 1531w, 1519w, ν(C-C,
C-N), 270s ν(Rh-Cl). 1H NMR (CDCl3, 293 K): δ 1.76 (s, 15H,
CH3Cp*), 2.43 (s, 6H, 5-CH3), 2.50 (s, 6H, 3-CH3), 5.95, 6.70 (d,
[Cp*Rh(L3)Cl][Cl] (9). A THF solution containing [Cp*RhCl-
(µ-Cl)]2 (0.182 g, 0.294 mmol) and L3 (0.103 g, 0.588 mmol) was
stirred for 96 h at room temperature under N2. The resulting red
precipitate was isolated by filtration and dried in vacuum. The
residue obtained was washed with 5 mL of THF and recrystallized
from 1:1 CH2Cl2/light petroleum (40-60 °C) and shown to be
compound 9 (0.262 g, 0.538 mmol, yield 91%). mp: 237-239 °C.
Anal. Calcd for C19H27Cl2N4Rh: C, 47.07; H, 5.61; N, 11.45.
Found: C, 46.64; H, 5.44; N, 11.24. IR (nujol, cm-1): 1560w,
1541w ν(C-C, C-N), 2.92s, 279s ν(Rh-Cl). 1H NMR (CDCl3,
293 K): δ 1.71 (s, 15H, CH3Cp*), 2.04 (s, 6H, 4-CH3), 5.80, 8.57
2
2H, CH2, Jgem ) 15.8 Hz), 6.03 (s, 2H, H4).
[Cp*Rh(L4)Cl][CF3SO3] (14). Compound 14 (0.232 g, 0.490
mmol, yield 70%) was prepared following a procedure similar to
that reported for 12 using [Cp*RhCl(µ-Cl)]2, L4, and AgCF3SO3.
Anal. Calcd for C20H27F3N4O3RhS: C, 42.64; H, 4.83; N, 9.94.
Found: C, 42.33; H, 5.04; N, 9.64. IR (nujol, cm-1): 3114s ν(CF3-
SO3), 1536w ν(C-C, C-N), 272s ν(Rh-Cl). 1H NMR (CD2Cl2,
293 K): δ 1.75 (s, 15H, CH3Cp*), 2.25, 2.58 (s, 6H, CH3gem), 6.59
(t, 2H, H4), 7.84 (d, 2H, H5), 8.03 (d, 2H, H3). 13C NMR (CD2-
Cl2, 293 K): δ 9.24 (s, CH3Cp*), 26.19, 29.44 (s, C(CH3)2), 77.10
(s, CH2), 97.47 (d, CCp*, J(103Rh-13C) ) 8.5 Hz), 108.56 (s, C4),
132.43 (s, C5), 147.50 (s, C3).
2
(d, 2Hgem, CH2(pz)2, J ) 14.2 Hz), 7.45 (s, 2H, H5-pz), 8.42 (s,
2H, H3-pz). 13C NMR (CD2Cl2, 293 K): δ 9.16 (s, 4-CH3), 9.65
(s, CH3Cp*), 63.00 (s, CH2), 96.80 (d, CCp*, J(103Rh-13C) ) 8.5
Hz), 119.23 (s, C4), 135.33 (s, C5), 144.74 (s, C3).
[Cp*Ir(L4)Cl][CF3SO3] (15). Compound 15 (0.220 g, 0.318
mmol, yield 54%) was prepared following a procedure similar to
that reported for 12 using [Cp*IrCl(µ-Cl)]2, L4, and AgCF3SO3.
Anal. Calcd for C20H27ClF3IrN4O3S: C, 34.91; H, 3.95; N, 8.14.
Found: C, 34.47; H, 3.80; N, 7.89. IR (nujol, cm-1): 3121m, ν(CF3-
[Cp*Ir(L3)Cl][Cl] (10). Compound 10 (0.288 g, 0.500 mmol,
yield 85%) was prepared following a procedure similar to that
reported for 4 using [Cp*IrCl(µ-Cl)]2 and L3. mp: 292-294 °C
(dec). Anal. Calcd for C19H27Cl2N4Ir: C, 39.72; H, 4.74; N, 9.75.
Found: C, 39.33; H, 4.82; N, 9.56. IR (nujol, cm-1): 1569w
1
SO3), 1511sh ν(C-C, C-N), 275s ν(Ir-Cl). H NMR (CD2Cl2,
293 K): δ 1.68 (s, 15H, CH3Cp*), 2.18, 2.64 (s, 6H, CH3gem), 6.64
(t, 2H, H4), 7.78 (d, 2H, H5), 8.09 (d, 2H, H3). 13C NMR (CD2-
Cl2, 293 K): δ 9.04 (s, CH3Cp*), 26.45, 28.65 (s, C(CH3)2), 78.24
(s, CH2), 89.34 (s, CCp*), 109.09 (s, C4), 132.40 (s, C5), 147.64 (s,
C3).
1
ν(C-C, C-N), 311s, 300s, 257w, ν(Ir-Cl). H NMR (CDCl3,
293 K): δ 1.67 (s, 15H, CH3Cp*), 2.06 (s, 6H, 4-CH3), 5.48, 9.06
(d, 2H, CH2, 2Jgem ) 13.8 Hz), 7.42 (s, 2H, H5), 8.44 (s, 2H, H3).
13C NMR (CD2Cl2, 293 K): δ 9.13 (s, CH3Cp*), 31.13 (s, 4-CH3),
62.49 (s, CH2), 88.71 (s, CCp*), 119.23 (s, C4), 134.67 (s, C5),
144.24 (s, C3).
[Cp*Rh(L1)(H2O)][CF3SO3]2 (16). A CH2Cl2 solution contain-
ing [Cp*RhCl(µ-Cl)]2 (0.077 g, 0.125 mmol), L1 (0.037 g, 0.250
mmol), and AgCF3SO3 (0.120 g, 0.500 mmol) was stirred at room
temperature under N2. After 2 h, the precipitate formed was isolated
by filtration and washed with acetone. The orange solution obtained
was evaporated under vacuum, and the residue was washed with
light petroleum and shown to be compound 16 (0.090 g, 0.128
mmol, 51%). It was recrystallized from CH2Cl2/light petroleum
(40-60 °C). Anal. Calcd for C19H25F6N4O7RhS2: C, 32.49; H, 3.59;
N, 7.98. Found: C, 32.60; H, 3.43; N, 7.34. 1H NMR ((CD3)2CO,
293 K): δ 1.91 (s, 15H, CH3Cp*), 6.72 (t, 2H, H4), 6.70 (br, 2H,
[Cp*Ir(L4)Cl][Cl] (11). Compound 11 (0.320 g, 0.560 mmol,
yield 85%) was prepared following a procedure similar to that
reported for 9 using [Cp*IrCl(µ-Cl)]2 and an excess of L4 (1:6).
mp: 278-279 °C. Anal. Calcd for C19H27Cl2IrN4: C, 39.72; H,
4.74; N, 9.75. Found: C, 39.33; H, 4.72; N, 9.46. IR (nujol, cm-1):
1
1537w, 1509sw ν(C-C, C-N), 367s, 245s ν(Ir-Cl). H NMR
(CDCl3, 293 K): δ 1.67 (s, 15H, CH3Cp*), 2.22, 2.87 (sbr, 6H,
CH3gem), 6.59 (sbr, 2H, H4), 7.70 (m, 2H, H5), 8.41 (sbr, 2H, H3).
13C NMR (CDCl3, 293 K): δ 9.24 (s, CH3Cp*), 27.60 (s, C(CH3)2),
79.93 (s, CH2), 89.18 (s, CCp*), 109.27 (s, C4), 133.77 (s, C5),
147.03 (s, C3).
1
CH2), 8.20 (d, 2H, H5), 8.33 (d, 2H, H3). H NMR ((CD3)2CO,
323 K): δ 1.91 (s, 15H, CH3Cp*), 6.72 (t, 2H, H4), 6.70 (sbr, 2H,
1
CH2), 8.20 (d, 2H, H5), 8.34 (d, 2H, H3). H NMR (CD3)2CO,
[Cp*Rh(L1)Cl][CF3SO3]‚2H2O (12). A CH2Cl2 solution con-
taining [Cp*RhCl(µ-Cl)]2 (0.182 g, 0.294 mmol) and L3 (0.087 g,
0.588 mmol) and AgCF3SO3 (0.151 g, 0.588 mmol) was stirred at
room temperature under N2. After 2 h, a colorless precipitate
formed, which was isolated by filtration and shown to be AgCl.
The clear orange solution obtained was evaporated under vacuum,
and the residue was washed with light petroleum and shown to be
compound 12 (0.270 g, 0.444 mmol, yield 75%). It was recrystal-
lized from CH2Cl2/light petroleum (40-60 °C). mp: 251-252 °C.
Anal. Calcd for C18H27ClF3N4O5RhS: C, 35.63; H, 4.48; N, 9.23.
Found: C, 36.05; H, 4.33; N, 9.34. IR (nujol, cm-1): 3535br
ν(H2O), 3117s ν(CF3SO3), 1524w ν(C-C, C-N), 1266s ν(CF3-
2
213 K): δ 1.92 (s, 15H, CH3Cp*), 6.26, 7.16 (d, 2H, CH2, Jgem
)
C
15.1 Hz), 6.67 (d, 2H, H5), 6.76 (t, 2H, H4), 8.28 (d, 2H, H3). 13
NMR ((CD3)2CO, 293 K): δ 9.40 (s, CH3Cp*), 63.87 (s, CH2), 99.60
(d, CCp*, J(103Rh-13C) ) 9.4 Hz), 110.10 (s, C4), 137.30 (s, C5),
146.37 (s, C3).
[Cp*Ir(L2)(H2O)][CF3SO3]2 (17). Compound 17 (0.123 g, 0.145
mmol, 58%) was prepared following a procedure similar to that
reported for 16 using [Cp*IrCl(µ-Cl)]2, L2, and AgCF3SO3. mp:
219-220 °C. Anal. Calcd for C23H33F6N4O7IrS2: C, 32.58; H, 3.92;
N, 6.61. Found: C, 32.40; H, 3.75; N, 6.55. IR (nujol, cm-1):
3200br, 1605s, 1562s ν(C-C, C-N), 572m, 515s, 462w. 1H NMR
((CD3)2CO, 293 K): δ 1.85 (s, 15H, CH3Cp*), 2.48 (s, 6H, 5-CH3),
1
2
SO3), 279s ν(Rh-Cl). H NMR (CD2Cl2, 293 K): δ 1.58 (s, 4H,
2.61 (s, 6H, 3-CH3), 5.91, 6.70 (d, 2H, CH2, Jgem ) 16.0 Hz),
H2O), 1.73 (s, 15H, CH3Cp*), 6.03, 7.34 (d, 2H, CH2, 2Jgem ) 14.6
Hz), 6.52 (t, 2H, H4), 7.75 (d, 2H, H5), 8.27 (d, 2H, H3). 13C NMR
6.41 (s, 2H, H4). 1H NMR (D2O, 293 K): δ 1.50 (s, 15H, CH3Cp*),
2.21 (s, 6H, 5-CH3), 2.34 (s, 6H, 3-CH3), 5.43, 6.25 (d, 2H, CH2,
904 Inorganic Chemistry, Vol. 46, No. 3, 2007

(η5-C5Me5)-Rhodium and -Iridium DeriWatiWes
2Jgem ) 15.6 Hz), 6.15 (s, 2H, H4). 13C NMR ((CD3)2CO, 293 K):
δ 9.69 (s, CH3Cp*), 11.43 (s, 5-CH3), 14.72 (s, 3-CH3), 58.84 (s,
CH2), 90.39 (s, CCp*), 110.12 (s, C4), 145.49 (s, C5), 154.38 (s,
C3).
(d, Cp), 133.90 (d, Co), 134.90 (d, Ci), 144.00 (s, C5), 155.04 (s,
C3). 31P NMR (CDCl3, 293 K):δ 30.96 (d,1J(31P-Rh) ) 144.0 Hz).
NOE Measurements. The 1H-NOESY30 NMR experiments were
acquired by the standard three-pulse sequence or by the PFG
version.31 Two-dimensional 19F,1H-HOESY NMR experiments were
acquired using the standard four-pulse sequence or the modified
version.32 The number of transients and the number of data points
were chosen according to the sample concentration and the desired
final digital resolution. Semiquantitative spectra were acquired using
a 1 s relaxation delay and 800 ms mixing times.
[Cp*Rh(L4)(H2O)][CF3SO3]2‚3H2O (18). Compound 18 (0.220
g, 0.318 mmol, yield 54%) was prepared following a procedure
similar to that reported for 16 using [Cp*RhCl(µ-Cl)]2 (0.182 g,
0.294 mmol), L4 (0.087 g, 0.588 mmol), and AgCF3SO3 (0.302 g,
0.588 mmol). Anal. Calcd for C21H35F6N4O10RhS2: C, 32.14; H,
4.50; N, 7.14. Found: C, 32.45; H, 4.44; N, 7.02. IR (nujol, cm-1):
3500br, 3143s ν(CF3SO3), 1538w ν(C-C, C-N). 1H NMR
(CD3)2CO, 293 K): δ 1.92 (s, 15H, CH3Cp*), 2.52 (sbr, 6H, CH3gem),
1
PGSE Experiments. H- and 19F-PGSE NMR measurements
were performed using the standard stimulated echo pulse sequence33
on a Bruker AVANCE DRX 400 spectrometer equipped with a
GREAT 1/10 gradient unit and a QNP probe with a Z-gradient
coil at 296 K without spinning. Me of the Cp* and fluorine
resonances were usually investigated. The dependence of the
resonance intensity (I) on a constant waiting time and on a varied
gradient strength (G) is described by eq 3
1
6.76 (t, 2H, H4), 8.38 (d, 2H, H5), 8.49 (d, 2H, H3). H NMR
(CD3)2CO, 253 K): δ 1.92 (s, 15H, CH3Cp*), 2.31, 2.73 (s, 6H,
1
CH3gem), 6.79 (t, 2H, H4), 8.37 (d, 2H, H5), 8.55 (d, 2H, H3). H
NMR (CD3)2CO, 213 K): δ 1.92 (s, 15H, CH3Cp*), 2.29, 2.72 (s,
6H, CH3gem), 5.95 (d, H2O), 6.81 (t, 2H, H4), 8.35 (d, 2H, H5),
8.57 (d, 2H, H3). 13C NMR ((CD3)2CO, 293 K): δ 9.45 (s, CH3Cp*),
78.44 (s, CH2), 99.45 (d, CCp*, J(103Rh-13C) ) 9.1 Hz), 109.35 (s,
C4), 134.50 (s, C5), 147.55 (s, C3).
I
I0
δ
3
ln ) -(γδ)2Dt ∆ - G2
(3)
(
)
[Cp*Ir(L4)(H2O)][CF3SO3]2 (19). Compound 19 (0.130 g, 0.158
mmol, yield 63%) was prepared following a procedure similar to
that reported for 16 using [Cp*IrCl(µ-Cl)]2, L4, and AgCF3SO3.
mp: 126-128 °C (dec). Anal. Calcd for C21H29F6N4O7IrS2: C,
30.77; H, 3.57; N, 6.83. Found: C, 30.95; H, 3.43; N, 6.62. IR
(nujol, cm-1): 3500s, 3142m, 1665m, 1613s, ν(C-C, C-N),
576m, 516m, 458w. 1H NMR ((CD3)2CO, 293 K): δ 1.82 (s, 15H,
CH3Cp*), 2.75 (sbr, 6H, CH3gem), 6.80 (t, 2H, H4), 8.34 (d, 2H, H5),
8.55 (d, 2H, H3). 1H NMR (D2O, 293 K): δ 1.51 (s, 15H, CH3Cp*),
1.93, 2.45 (s, 6H, CH3gem), 6.57 (t, 2H, H4), 7.94 (d, 2H, H5), 8.15
(d, 2H, H3). 13C NMR ((CD3)2CO, 293 K): δ 9.28 (s, CH3Cp*),
79.76 (s, CH2), 90.69 (s, CCp*), 110.16 (s, C4), 134.95 (s, C5),
148.32 (s, C3).
where I ) intensity of the observed spin echo, I0 ) intensity of the
spin echo without gradients, Dt ) diffusion coefficient, ∆ ) delay
between the midpoints of the gradients, δ ) length of the gradient
pulse, and γ ) magnetogyric ratio.
The shape of the gradients was rectangular; their duration (δ)
was 4-5 ms, and their strength (G) was varied during the
experiments. All the spectra were acquired using 32 K points with
a spectral width of 5000 Hz and were processed with a line
broadening of 1.0 Hz. The semilogarithmic plots of ln(I/I0) versus
G2 were fitted using a standard linear regression algorithm; the R
factor was always higher than 0.99. Different values of ∆, nt
(number of transients), and number of different gradient strengths
(G) were used for different samples.
PGSE data were treated18 taking advantage of an internal standard
(TMSS [tetrakis-(trimethylsilyl)silane], the dimension of which is
known from the literature34), and introducing into the Stokes-
Einstein equation the semiempirical estimation of the c factor that
can be obtained through eq 435 derived from the microfriction theory
proposed by Wirtz and co-workers,36 in which c is expressed as a
function of the solute to solvent ratio of radii.
[Cp*Rh(L1)(H2O)][ClO4]2 (20). Compound 20 (0.316 g, 0.520
mmol, yield 88%) was prepared following a procedure similar to
that reported for 16 using [Cp*RhCl(µ-Cl)]2, L1, and AgCF3SO3.
Anal. Calcd for C17H29Cl2N4O9Rh: C, 33.66; H, 4.82; N, 9.24.
Found: C, 33.20; H, 4.63; N, 9.14. IR (nujol, cm-1): 1521w,
1
ν(C-C, C-N), 1089s, 622m ν(ClO4). H NMR ((CD3)2CO, 293
K): δ 1.90 (s, 15H, CH3Cp*), 6.75 (t, 2H, H4), 6.79 (br, 2H, CH2),
8.28 (d, 2H, H5), 8.37 (d, 2H, H3). 1H NMR ((CD3)2CO, 323 K):
δ 1.90 (s, 15H, CH3Cp*), 6.75 (t, 2H, H4), 6.82 (sbr, 2H, CH2),
1
8.28 (d, 2H, H5), 8.37 (d, 2H, H3). H NMR (CD3)2CO, 213 K):
6
δ 1.92 (s, 15H, CH3Cp*), 6.28, 7.18 (d, 2H, CH2, 2Jgem ) 15.0 Hz),
6.69 (d, 2H, H5), 6.78 (t, 2H, H4), 8.30 (d, 2H, H3). 13C NMR
((CD3)2CO, 293 K): δ 9.44 (s, CH3Cp*), 63.96 (s, CH2), 99.64 (d,
c )
(4)
2.234
rsolv
rH
1 + 0.695
(
)
[
]
C
Cp*, J(103Rh-13C) ) 9.1 Hz), 110.29 (s, C4), 137.04 (s, C5),
146.27 (s, C3).
From the Stokes-Einstein equation Dt ) kT/cπηrH and eq 4,
the ratio of the Dt values for the standard TMSS (st) and sample
(sa), which is also equal to the ratio of the slopes (m) of the straight
lines from the plot of log(I/Io) versus G2 (eq 3), is
[Cp*Rh(L2)(PPh3)][Cl][SO3CF3] (21). A CH2Cl2 solution con-
taining 13 (0.080 g, 0.133 mmol) and PPh3 (0.035 g, 0.133 mmol)
was stirred at room temperature under N2. After 6 h, the solution
was isolated by filtration, and the orange solution obtained was
evaporated under vacuum; the product was shown to be compound
21 (0.064 g, 0.072 mmol, yield 54%). mp: 139-140 °C. Anal.
Calcd for C40H46ClF3N4O3PRhS: C, 54.03; H, 5.21; N, 6.30.
Found: C, 54.44; H, 5.60; N, 5.79. IR (nujol, cm-1): 1521w
ν(C-C, C-N), 1089s, 622m ν(ClO4). 1H NMR (CDCl3, 273 K):
δ 1.71 (s, 15H, CH3Cp*), 2.42 (s, 6H, 5-CH3), 2.49 (s, 6H, 3-CH3),
(30) Jeener, J.; Meier, B. H.; Bachmann, P.; Ernst, R. R. J. Chem. Phys.
1979, 71, 4546.
(31) Wagner, R.; Berger, S. J. Magn. Reson. A 1996, 123, 119.
(32) Lix, B.; So¨nnichsen, F. D.; Sykes, B. D. J. Magn. Reson. A 1996,
121, 83.
(33) Stilbs, P. Prog. Nucl. Magn. Reson. Spectrosc. 1987, 19, 1.
(34) Dinnebier, R. E.; Dollase, W. A.; Helluy, X.; Ku¨mmerlen, J.; Sebald,
A.; Schmidt, M. U.; Pagola, S.; Stephens, P. W.; van Smaalen, S.
Acta Crystallogr. 1999, B55, 1014.
(35) (a) Chen, H.-C.; Chen, S.-H. J. Phys. Chem. 1984, 88, 5118. (b)
Espinosa, P. J.; de la Torre, J. G. J. Phys. Chem. 1987, 91, 3612.
(36) (a) Gierer, A.; Wirtz, K. Z. Naturforsch. A 1953, 8, 522. (b) Spernol,
A.; Wirtz, K. Z. Naturforsch. A 1953, 8, 532.
2
5.99, 6.70 (d, 2H, CH2, Jgem ) 15.6 Hz), 6.03 (s, 2H, H4) 7.32
(m, 15H, PPh3). 13C NMR (CDCl3, 293 K): δ 9.83 (s, CH3Cp*),
11.57 (s, 5-CH3), 15.25 (s, 3-CH3), 58.05 (s, CH2), 97.09 (d, CCp*
,
J(103Rh-13C) ) 8.3 Hz), 109.53 (s, C4), 128.75 (d, Cm), 129.13
Inorganic Chemistry, Vol. 46, No. 3, 2007 905

Pettinari et al.
st
Dsta cstrH
mst Dstt csarH
Crystal/Refinement Data. The crystal and refinement data are
given in Table 3.
msa
)
)
) f(rsolv,rsHa,rHst)
(5)
sa
4‚H2O. A difference map residue was modeled and refined as a
water molecule oxygen atom. Reflection weights were (σ2(F2) +
Equation 5 circumvents the dependence of the Dt values on the
temperature, solution viscosity (which changes when the concentra-
tion of the sample is varied), and gradient calibration, and allows
an accurate value of the hydrodynamic radius18 to be obtained.
The uncertainty of the measurements was estimated by determin-
ing the standard deviation of m by performing experiments with
different ∆ values. The standard propagation of error analysis gave
a standard deviation of approximately 3-4% in hydrodynamic radii
33F2)-1
.
6‚2H2O. Difference map residues were modeled in terms of
major and minor components of uncoordinated chlorine atoms and
oxygen atoms in concert, associated hydrogen atoms not being
located, component site occupancies refining to 0.761(4) and
complement.
6‚1/2CH2Cl2. The solvent component was modeled as disordered
CH2Cl2, geometries constrained to estimated values, site occupan-
cies 0.5.
7. The compound is quasi-isomorphous with 5. In 5, the cp rings
were modeled as disordered over two sets of sites; in the present,
such disorder was not resolvable, although refinement of the atoms
as single components resulted in unacceptable ellipsoids with the
isotropic forms ultimately being adopted. Attempted refinement in
lower symmetry in both cases was unfruitful.
and 10-15% in hydrodynamic volumes. The Van der Waals volume
37
(VvdW
)
was computed using the software package WebLab
ViewerLite 4.0.
Structure Determinations. Full spheres of CCD area-detector
diffractometer data were measured (ω-scans, monochromatic Mo
KR radiation, λ ) 0.71073 Å) yielding Nt(otal) reflections; these were
merged to N unique (Rint cited) after “empirical”/multiscan absorp-
tion correction, No with I > 2σ(I) being considered to be observed.
All reflections were used in the full-matrix least-squares refinements
on F2, refining anisotropic displacement parameter forms for the
non-hydrogen atoms, hydrogen atoms being included with param-
eters derivative of a riding model. Reflection weights were (σ2(F2)
15. Reflections weight were (σ2(F2) + 193F2)-1
16. “Friedel” data were preserved distinct; xabs refined to
0.00(4).
.
18‚3H2O. Difference map residues were modeled as water
molecule oxygen atoms. No associated hydrogen atoms were
+ (nwP)2 + nw′P)-1 (P ) (Fo + 2Fc2)/3). Neutral atom complex
2
located. Reflection weights were (σ2(F2) + 33F2)-1
.
scattering factors were employed within the Xtal 3.7 and SHELXL
97 program systems.38,39 Pertinent results are given in the tables
and figures, the latter showing 50% probability amplitude envelopes
for the non-hydrogen atoms, hydrogen atoms having arbitrary radii
of 0.1 Å.
(Note: Initial studies on 5, 7, and 6‚1/2CH2Cl2 resulted in inferior
determinations; further attempts on recrystallized samples resulted
in no improvement for 5, but for 6, a new form was defined, 6‚
2H2O, yielding a superior result.)
Acknowledgment. Support from the Universities of
Camerino, Perugia, and Western Australia is gratefully
acknowledged. This work has been partially supported by
the Fondazione CARIMA). A.M. and D.Z. thank the Min-
istero dell’Istruzione, dell’Universita` e della Ricerca (MIUR,
Rome, Italy), Programma di Rilevante Interesse Nazionale,
Cofinanziamento 2004-2005 for support.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of 4, 5, 6 (two forms),
7, 15, 16 and 18. This material is available free of charge via the
Internet at http://pubs.acs.org.
(37) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(38) Hall, S. R., du Boulay, D. J., Olthof-Hazekamp, R., Eds. The Xtal 3.7
System; University of Western Australia: Crawley, Australia, 2001.
(39) Sheldrick, G. M. SHELXL-97, A Program for Crystal Structure
Refinement; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
IC061928G
906 Inorganic Chemistry, Vol. 46, No. 3, 2007