Cu(I) complexes bearing the new sterically demanding and coordination flexible tris(3-phenyl-1-pyrazolyl)methanesulfonate ligand and the water-soluble phosphine 1,3,5-triaza-7-phosphaadamantane or related ligands

Article abstract of DOI:10.1021/ic801254b

The new sterically hindered scorpionate tris(3-phenylpyrazolyl) methanesulfonate (Tpms^Ph)^- has been synthesized and its coordination behavior toward a Cu(I) center, in the presence of 1,3,5-triaza-7-phosphaadamantane (PTA), N-methyl-1,3,5-triaza-7- phosphaadamantane tetraphenylborate ((mPTA)[BPh₄]) or hexamethylenetetramine (HMT) has been studied. The reaction between Li(Tpms ^Ph) (1) and [Cu(MeCN)₄][PF₆] yields [Cu(Tpms^Ph)(MeCN)] (2) which, upon further acetonitrile displacement on reaction with PTA, HMT, or (mPTA)[BPh₄], gives the corresponding complexes [Cu(Tpms^Ph)(PTA)] (3), [Cu(Tpms^Ph)(HMT)] (4), and [Cu(Tpms^Ph)(mPTA)][PF₆] (5). All the compounds have been characterized by ¹H, ³¹P, ¹³C, COSY or HMQC-NMR, IR, elemental analysis, and single crystal X-ray diffraction. In the complexes (3) and (5), which bear a phosphine ligand (i.e., PTA and mPTA, respectively), the new scorpionate ligand shows the typical N,N,N-coordination mode, whereas in (2) and (4), bearing a N-donor ligand (i.e., MeCN and HMT, respectively), it binds the metal via the N,N,O chelating mode, involving the sulfonate moiety.

Full text of DOI:10.1021/ic801254b

Inorg. Chem. 2008, 47, 10158-10168
Cu(I) Complexes Bearing the New Sterically Demanding and
Coordination Flexible Tris(3-phenyl-1-pyrazolyl)methanesulfonate Ligand
and the Water-Soluble Phosphine 1,3,5-Triaza-7-phosphaadamantane or
Related Ligands
Riccardo Wanke,† Piotr Smolen´ski,† M. Fa´tima C. Guedes da Silva,†,‡ Lu´ısa M. D. R. S. Martins,†,§
and Armando J. L. Pombeiro*,†
Centro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, TU Lisbon, AV. RoVisco
Pais, 1049-001 Lisbon, Portugal, UniVersidade Luso´fona de Humanidades e Tecnologias, Campo
Grande 376, 1749-024 Lisbon, Portugal, and Departamento de Engenharia Qu´ımica, ISEL, R.
Conselheiro Em´ıdio NaVarro, 1950-062 Lisbon, Portugal
Received July 4, 2008
The new sterically hindered scorpionate tris(3-phenylpyrazolyl)methanesulfonate (TpmsPh)- has been synthesized
and its coordination behavior toward a Cu(I) center, in the presence of 1,3,5-triaza-7-phosphaadamantane (PTA),
N-methyl-1,3,5-triaza-7-phosphaadamantane tetraphenylborate ((mPTA)[BPh4]) or hexamethylenetetramine (HMT)
has been studied. The reaction between Li(TpmsPh) (1) and [Cu(MeCN)4][PF6] yields [Cu(TpmsPh)(MeCN)] (2) which,
upon further acetonitrile displacement on reaction with PTA, HMT, or (mPTA)[BPh4], gives the corresponding
complexes [Cu(TpmsPh)(PTA)] (3), [Cu(TpmsPh)(HMT)] (4), and [Cu(TpmsPh)(mPTA)][PF6] (5). All the compounds
1
have been characterized by H, 31P, 13C, COSY or HMQC-NMR, IR, elemental analysis, and single crystal X-ray
diffraction. In the complexes (3) and (5), which bear a phosphine ligand (i.e., PTA and mPTA, respectively), the
new scorpionate ligand shows the typical N,N,N-coordination mode, whereas in (2) and (4), bearing a N-donor
ligand (i.e., MeCN and HMT, respectively), it binds the metal via the N,N,O chelating mode, involving the sulfonate
moiety.
Introduction
In pursuit of our recent investigation of the coordination
chemistry of N-, P- and O-donor ligands,3 including the
scorpionate-type tris(pyrazolyl)methane,4 toward copper(I)
and (II) centers, we have now focused our attention on the
Copper species are widely present in Nature as mono- or
multinuclear metal complexes and play a crucial role in
different enzymes and catalytic systems, leading to a
currently growing interest in the development of new copper
models.1 In bioinorganic and organometallic chemistry the
systems involving this metal represent one of the most
relevant areas of investigation.2
(2) (a) Kim, E.; Chufan, E. E.; Kamarai, K.; Karlin, K. D. Chem. ReV.
2004, 104, 1077–1133. (b) Chen, P.; Gorelsky, S. I.; Ghosh, S.;
Solomon, E. I. Angew. Chem., Int. Ed. 2004, 43, 4132–4140. (c) Koval,
I. A.; Belle, C.; Selmeczi, K.; Philouse, C.; Saint-Aman, E.; Schuitema,
A. M.; Gamez, P.; Pierre, J. L.; Reedijk, J. J. Biol. Inorg. Chem. 2005,
10, 739–750. (d) Koval, I. A.; Pursche, D.; Stassen, A. F.; Gamez, P.;
Krebs, B.; Reedijk, J. Eur. J. Inorg. Chem. 2003, 9, 1669–1674. (e)
Uber, J. S.; Vogels, Y.; Van Den Helder, D.; Multikainen, I.;
Turpeinen, U.; Fu, W. T.; Roubeau, O.; Gamez, P.; Reedijk, J. Eur.
J. Inorg. Chem., 2007, 26, 4197-4206.
* To whom correspondence should be addressed. E-mail: pombeiro@
ist.utl.pt. Fax: +351-21-846 4455.
†
TU Lisbon.
‡
Universidade Luso´fona de Humanidades e Tecnologias.
Departamento de Engenharia Qu´ımica, ISEL.
§
(1) (a) Solomon, E. I.; Sundaram, U. M.; Machonkin, T. E. Chem. ReV.
1996, 96, 2563–2605. (b) Klinman, J. P. Chem. ReV. 1996, 96, 2541–
2561. (c) Koval, I. A.; Gamez, P.; Belle, C.; Selmeczi, K.; Reedijk, J.
Chem. Soc. ReV. 2006, 35, 814–840. (d) Maheswari, P. U.; Roy, S.;
den Dulk, H.; Barends, S.; van Wezel, G.; Kozlevcar, B.; Gamez, P.;
Reedijk, J. J. Am. Chem. Soc. 2006, 128, 710–711. (e) Elsevier, C. J.;
Reedijk, J.; Walton, P. H.; Ward, M. D. Eur. J. Inorg. Chem. 2003,
9, 1669–1674. (f) Elsevier, C. J.; Reedijk, J.; Walton, P. H.; Ward,
M. D. Dalton Trans. 2003, 10, 1869–1880.
(3) (a) Kirillow, A. M.; Kopylovich, M. N.; Kirillova, M. V.; Haukka,
M.; da Silva, M. F. C. G.; Pombeiro, A. J. L. Angew. Chem., Int. Ed.
2005, 44, 4345–4349. (b) Di Nicola, C.; Kabarach, Y. Y.; Kirillov,
A. M.; Monari, M.; Pandolfo, L.; Pettinari, C.; Pombeiro, A. J. L.
Inorg. Chem. 2007, 46, 221–230.
(4) (a) Alegria, E. C. B.; Martins, L. M. D. R. S.; Haukka, M.; Pombeiro,
A. J. L. Dalton Trans. 2006, 41, 4954–4961. (b) Alegria, E. C. B.;
Martins, L. M. D. R. S.; da Silva, M. F. C. G.; Pombeiro, A. J. L. J.
Organomet. Chem. 2005, 690, 1947–1958.
10158 Inorganic Chemistry, Vol. 47, No. 21, 2008
10.1021/ic801254b CCC: $40.75  2008 American Chemical Society
Published on Web 10/08/2008

Scorpionate Tris(3-phenylpyrazolyl)methanesulfonate Ligand
synthesis of a new class of copper complexes bearing a
sterically hindered chelating facially binding scorpionate that
could modulate the coordination properties of the metal
center.
demanding features of the 3-substituted tris(pyrazolyl)
ligands. For these purposes, we designed a new Tpms
derivative bearing a phenyl ring at the 3-position of pyrazolyl
rings. When ligating a metal center, such a bulky species
would be expected to provide a “steric control” on the other
coordination position(s) of the complex, selecting the suitable
ligands on the opposite side, namely preventing the formation
of “sandwich” complexes (with two of such scorpionate
ligands).12 Hence, herein we present the synthesis of the new
tris(3-phenylpyrazolyl)methanesulfonate (TpmsPh)- species,
its coordination behavior toward copper(I), and the reactions
with the two water soluble phosphines13 1,3,5-triaza-7-
phosphaadamantane (PTA) and N-methyl-1,3,5-triaza-7-
phosphaadamantane tetraphenyl borate ((mPTA)[BPh4]), and
the related hexamethylenetetramine (HMT). The coordination
chemistry of the aqua-soluble PTA and (mPTA)+ species
has received an increased interest in recent years13b on
account of the enhanced solubility in water of their com-
plexes, a feature of interest for applications in biological
systems14 and aqueous phase catalysis.15 The new water
soluble complexes could represent a potentially active class
of catalysts bearing a flexibile labile ligand that would
provide a convenient entry to further reactivity studies (i.e.,
dioxygen activation, coordination of small molecules, de-
velopment of inorganic enzyme models7e).
Metal complexes of tris(pyrazolyl)borate (Tp) and derived
ligands constitute one of the most extensively studied classes
of coordination compounds in inorganic, organometallic, and
bioinorganic chemistries,5,6 and, for instance, several ex-
amples of the use of Tp complexes to mimic enzymatic
systems have been reported.7 In contrast, the coordination
chemistry of the isoelectronic tris(pyrazolyl)methane
(HC(pz)3, Tpm, pz ) pyrazolyl) type ligands is much less
studied. One reason for the limited research in this area is
that the syntheses of the latter ligands, with the exception
of Tpm itself, are more difficult than those of the tris(pyra-
zolyl)borate analogues.8 A “second generation” of tris(pyra-
zolyl) ligands, introduced again by Trofimenko,9 in which
the pyrazolyl rings contain bulky substituents, especially at
the 3-position, offers the opportunity to tune the coordination
behavior toward different metal centers.
More recently, Kla¨ui reported the synthesis of tris(pyra-
zolyl)methanesulfonate (Tpms) salts and their derivatives as
a novel and more hydrophilic class of ligands.10 Moreover,
these ionic functionalized tris(pyrazolyl)methane derivatives
exhibit a relevant coordination versatility, acting as either a
tripodal or a bipodal ligand (i.e., with N3-, N2O-, N2- or NO-
coordination modes) with the possibility of involving the
sulfonate moiety in the coordination.11 This flexibility allows
exploring the behavior of the resulting complexes toward
further ligand binding to the metal center.
Experimental Section
General Materials and Experimental Procedures. All syn-
theses were carried out under an atmosphere of dinitrogen, using
standard Schlenk techniques. All solvents were dried, degassed,
and distilled prior to use. The reagents [Cu(MeCN)4][PF6], hex-
amethylenetetramine (HMT), Na[BPh4], 3-phenyl-1H-pyrazole, and
sulfur trioxide-trimethylamine complex were purchased from Al-
drich and used without further purification. 1,3,5-triaza-7-phos-
phaadamantane (PTA) and N-methyl-1,3,5-triaza-7-phosphaada-
mantane iodide ([mPTA]I) were synthesized in accordance with
The study we now report is aimed at the synthesis and
investigation of the coordination behavior of a new scorpi-
onate that could combine the flexibility and water solubility
of the sulfonato-functionalized class with the sterically
(5) (a) Trofimenko, S. J. Am. Chem. Soc. 1966, 88, 1842–1844. (b)
Trofimenko, S. Scorpionates: The Coordination Chemistry of Poly-
pyrazolylborates Ligands; Imperial College Press: London, 1999.
(6) (a) McCleverty, J. A.; Meyer, T. J. ComprehensiVe Coordination
Chemistry II: From Biology to Nanotechnology; Elsevier: Amsterdam,
2003; Vol. 1. (b) Byers, P. K.; Canty, A. J.; Skelton, B. W.
Organometallics 1990, 9, 826–832. (c) Bigmore, H. R.; Lawrence,
C. S.; Mountford, P.; Tredget, C. S. Dalton Trans. 2005, 635–651.
(d) Pettinari, C.; Pettinari, R. Coord. Chem. ReV. 2005, 249, 525–
543. (e) Kitajima, N. AdV. Inorg. Chem. 1992, 39, 1–77.
(7) (a) Looney, A.; Han, R.; McNeill, K.; Parkin, G. J. Am. Chem. Soc.
1993, 115, 4690–4697. (b) Parkin, G. Chem. Commun. 2000, 1971–
1985. (c) Vahrenkamp, H. Acc. Chem. Res. 1999, 32, 589–596. (d)
Schneider, J. L.; Carrier, S. M.; Ruggiero, C. E.; Young, V. G.;
Tolman, W. B. J. Am. Chem. Soc. 1998, 120, 11408–11418. (e) Hu,
Z.; Williams, R. D.; Tran, D.; Spiro, T. G.; Gorun, S. M. J. Am. Chem.
Soc. 2000, 122, 3556–3557. (f) Beck, A.; Weibert, B.; Burzlaff, N.
Eur. J. Inorg. Chem. 2001, 2, 521–527.
(8) Reger, D. L.; Grattan, T. C. Synthesis 2003, 350–356.
(9) (a) Trofimenko, S. Chem. ReV. 1993, 93, 943–980. (b) Kitajima, N.;
Tolman, W. B. Prog. Inorg. Chem. 1995, 43, 419–531. (c) Kealey,
S.; Long, N. J.; Miller, P. W.; White, A. J. P.; Gee, A. D. Dalton
Trans. 2008, 20, 2677–2679.
(10) Kla¨ui, W.; Berghahn, M.; Rheinwald, G.; Lang, H. Angew. Chem.,
Int. Ed. 2000, 39, 2464–2466.
(11) (a) Kla¨ui, W.; Peters, W.; Rheinwald, G.; Lang, H. Eur. J. Inorg. Chem.
2001, 6, 1415–1424. (b) Kla¨ui, W.; Berghahn, M.; Sho¨nherr, T.;
Rheinwald, G.; Lang, H. Eur. J. Inorg. Chem. 2003, 11, 2059–2070.
(c) Papish, E. T.; Taylor, M. T.; Jernigan, F. E.; Rodig, M. J.; Shewhan,
R. R.; Yap, G. P. A.; Jove´, F. A. Inorg. Chem. 2006, 45, 2242–2250.
(d) Chenskaya, T. B.; Berghahn, M.; Kunz, P. C.; Frank, W.; Kla¨ui,
W. J. Mol. Struct. 2007, 829, 135–148.
(12) (a) Edwards, P. G.; Harrison, A.; Newman, P. D.; Zhang, W. Inorg.
Chim. Acta 2006, 359, 3549–3556. (b) Trofimenko, S.; Calabrese, J. C.;
Domille, P. J.; Thompson, J. S. Inorg. Chem. 1989, 28, 1091–1101.
(13) (a) Pruchnik, F. P.; Smolenski, P. Appl. Organomet. Chem. 1999, 13,
829–836. (b) Phillips, A. D.; Gonsalvi, L.; Romerosa, A.; Vizza, F.;
Peruzzini, M. Coord. Chem. ReV. 2004, 248, 955–993.
(14) (a) Romerosa, A.; Campos-Malpartida, T.; Lidrissi, C.; Saoud, M.;
Serrano-Ruiz, M.; Perruzzini, M.; Garrido-Cardenas, J. A. G.; Garcia-
Maroto, F. G. Inorg. Chem. 2006, 45, 1289–1298. (b) Romerosa, A.;
Saoud, M.; Campos-Malpartida, T.; Lidrissi, C.; Serrano-Ruiz, M.;
Peruzzini, M.; Garrido, J. A.; Garcia-Maroto, F. G. Eur. J. Inorg.
Chem. 2007, 18, 2803–2812. (c) Romerosa, A.; Bergamini, P.;
Bertolasi, V.; Canella, A.; Cattabriga, M.; Gavioli, R.; Man˜as, S.;
Mantovani, N.; Pellicani, L. Inorg. Chem. 2004, 43, 905–913. (d)
Bergamini, P.; Bertolasi, V.; Martelli, L.; Canella, A.; Cattabriga, M.;
Gavioli, R.; Man˜as, S.; Romerosa, A. Inorg. Chem. 2007, 46, 4267–
4276. (e) Scolaro, C.; Geldbach, T. J.; Rochat, S.; Dorcier, A.; Gossens,
C.; Bergamo, A.; Cocchietto, M.; Tavernelli, I.; Sava, G.; Rothlis-
berger, U.; Dyson, P. J. Organometallics 2006, 25, 756–765. (f)
Scolaro, C.; Bergamo, A.; Brescacin, L.; Delfino, R.; Cocchietto, M.;
Laurenczy, G.; Geldbach, T. J.; Sava, G.; Dyson, P. J. J. Med. Chem.
2005, 12, 4161–4171.
(15) (a) Aqueous Phase Organometallic Catalysis; Horvath, I. T., Jou¨, F.
Eds.; Wiley-VCH: Weinheim, 1998. (b) Smolenski, P.; Pruchnik, F. P.;
Ciunik, Z. T. L. Inorg. Chem. 2003, 42, 3318–3322. (c) Pruchnik,
F. P.; Smolenski, P.; Wajda-Hermanowicz, K. J. Organomet. Chem.
1998, 570, 63–69.
Inorganic Chemistry, Vol. 47, No. 21, 2008 10159

Wanke et al.
literature methods,16 whereas hydrotris(3-phenylpyrazolyl)methane
(TpmPh) was prepared by modifying a published procedure.17 C,
H, and N analyses were carried out by the Microanalytical Service
) 2.7 Hz, 5-H (pz)), 7.77 (d, 6H, JHH ) 8.1 Hz, o-H (Ph)),
7.37-7.24 (m, 9H, m-H and p-H (Ph)), 6.83 (d, 3H, JHH ) 2.7 Hz,
4-H (pz)). 13C NMR (300 MHz, acetone-d6): 151.1 (s, 3-C (pz)),
134.4 (s, 5-C (pz)), 133.5 (s, pz-C (Ph)), 128.3 (s, o-C (Ph)), 127.6
(s, p-C (Ph)), 125.8 (s, m-C (Ph)), 103.5 (s, 4-C (pz)), 99.9
(s, O3SC).
of the Instituto Superior Te´cnico. Infrared spectra (4000-400 cm-1
)
were recorded on a BIO-RAD FTS 3000MX instrument in KBr
1
pellets. H, 13C, and 31P NMR spectra were measured on Bruker
1
300 and 400 UltraShieldTM spectrometers. H and 13C chemical
Synthesis of (mPTA)[BPh4]. A methanolic solution (25 mL)
of Na[BPh4] (342 mg, 1.00 mmol) was added to a solution (25
mL) of [mPTA]I (300 mg, 1.00 mmol) in the same solvent. The
resulting white suspension was stirred for 15 min and the solid
was then filtered off, washed with methanol (3 × 10 mL) and dried
under vacuum giving a white powder, which was crystallized from
acetone/methanol leading to the colorless crystalline product
(mPTA)[BPh4], in about 80% yield. The compound is well soluble
in medium polarity solvents like Me2CO, CHCl3, and CH2Cl2,
sparingly soluble in H2O (S25°C ) 0.2 mg·mL-1), MeOH, EtOH
and DMSO, and insoluble in C6H6 and Et2O. (mPTA)-
[BPh4]·0.25MeOH, BC31,25H36N3OP (499.41): calcd C 75.16, N
8.41, H 7.21; found C 75.03, N 8.80, H 7.24. IR (KBr): 3052 (m
br), 2996 (m br), 2984 (m br), 2965 (m br), 2921(m br), 1580 (m,
ν(CdC)), 1478 (m), 1452 (w), 1426 (m), 1311 (m), 1271 (m), 1247
(m), 1123 (m), 1099 (m), 1025 (m), 982 (m), 913 (m), 804 (m),
751 (s), 737 (s, ν(BPh4-)), 709 (s, ν(BPh4-)), 602 (m), 554 (m)
cm-1. 1H NMR (300 MHz, acetone-d6): δ 7.34 (br s, 8H, o-H (Ph)),
6.92 (dd, vt, JHH ) 6.9 Hz 8H, m-H (Ph)), 6.78 (dd, vt, 4H, p-H
(Ph)), 5.13 and 5.04 (J(HAHB) ) 13.2 Hz, 4H, NCHAHBN+), 4.70
and 4.52 (J(HAHB) ) 14.0 Hz, 2H, NCHAHBN), 4.54 (s, 2H,
shifts δ are expressed in ppm relative to Si(Me)4 and δ(31P) relative
to 85% H3PO4. Coupling constants are in Hz; abbreviations: s,
singlet; d, doublet; m, complex multiplet; vt, virtual triplet; br,
broad.
Synthesis of HC(3-Phpz)3, TpmPh. To a vigorously stirred
suspension of 3-phenyl-1H-pyrazole (5.00 g, 34.7 mmol) and
tetrabutylammonium bromide (0.56 g, 1.70 mmol) in water (70 mL)
was added an excess of Na2CO3 (22.0 g, 208 mmol) during 30
min. Then chloroform (17 mL) was added, and the final mixture
was refluxed for 84 h. The reaction mixture was then cooled to
room temperature, and toluene (20 mL) and water (15 mL) were
added. The organic phase was separated, washed with water, brine,
dried over Na2SO4, and evaporated under vacuum to give a brown
oil. This crude oil was dissolved in toluene (40 mL) and a catalytic
amount (ca. 80 µL, 1.0 mmol) of trifluoroacetic acid (TFA) was
added to this solution which was then refluxed for 1 day. After
this, the solution was cooled down to room temperature, washed
with water (2 × 15 mL) and neutralized with an aqueous solution
of NaHCO3. The organic phases were collected, washed with water
and brine, then dried over Na2SO4 and evaporated. The crude solid
was triturated in diisopropyl ether to give an off-white powder of
TpmPh (3.2 g, 62%). The compound is well soluble in medium and
high polarity solvents like Me2CO, CHCl3, CH2Cl2, MeOH, EtOH,
and DMSO and insoluble in H2O. HC(3Phpz)3, C28H22N6 (442.51):
calcd C 75.99, N 18.99, H 5.01; found C 75.86, N 18.71, H 5.39.
IR (KBr): 3162 (w) 1529 (m, ν(C)N)), 1502 (m), 1456 (s), 1240
3
PCH2N+), 4.09 and 3.94 (J(HAHB) ) 15.0 Hz, J(HA-P) ) 15.0
3
Hz, J(HB-P) ) 9.6 Hz, 4H, PCHAHBN), 2.81 (s, 3H, N+CH3).
31P{1H} NMR (162.0 MHz, acetone-d6): -85.4 (s). 31P{1H} NMR
(162.0 MHz, DMSO-d6): -87.0 (s). 13C{1H} and HMQC 13C-1H
NMR (100.6 MHz, acetone-d6): 165.7 - 164.2 (4s, 1-C, BPh4), 137.0
(s, 2-C, BPh4), 126.1 - 126.0 (4s, 3-C, BPh4), 122.3 (s, 4-C, BPh4),
81.9 (s, NCH2N+), 70.6 (s, NCH2N), 57.3 (dd, vt, 1J(C-P) ) 33.6
Hz, PCH2N+), 50.4 (s, N+CH3), 46.6 (dd, vt, 1J(C-P) ) 20.8 Hz,
PCH2N).
1
(s), 1077 (s), 1050 (s), 809 (s), 756 (s), 693 (s) cm-1. H NMR
(300 MHz, acetone-d6): 8.86 (s, 1H, HC), 8.11 (d, 3H, JHH ) 2.6
Hz, 5-H (pz)), 7.90 (d, 2H, JHH ) 8.1 Hz, o-H (Ph)), 7.42 (dd, vt,
6H, m-H (Ph)), 7.35 (dd, vt, 3H, p-H (Ph)), 6.90 (dd, vt, 3H, JHH
) 2.6 Hz, 4-H (pz)).
Synthesis of [Cu{O3SC(3-Phpz)3}(MeCN)], [Cu(TpmsPh)(MeCN)],
(2). Compound (2) was prepared by adding 5 mL of a methanolic
Synthesis of Li[O3SC(3-Phpz)3], Li(TpmsPh), (1). A 1.6 M
solution of butyllithium (1.6 mL, 2.7 mmol, 1.1 equiv) in hexane
was added dropwise to tris(3-phenylpyrazolyl)methane TpmPh (1.00
g, 2.26 mmol, 1.0 equiv) in dry tetrahydrofuran (THF) at -65 °C.
The solution turned red/brown and was stirred for 1 h at -60 °C.
Sulfur trioxide-trimethylamine complex (330 mg, 2.38 mmol, 1.05
equiv) was added at -60 °C, and the reaction was allowed to warm
to room temperature overnight. The solvent was evaporated, and
the residue was dried under vacuum at room temperature for 2 h.
It was then suspended in THF and filtered to yield a white powder
of (1) (0.66 g, 56%). The compound is well soluble in medium
and high polarity solvents like H2O (S25°C ≈ 90 mg ·mL-1), Me2CO,
CHCl3, MeOH, EtOH, and DMSO, and insoluble in Et2O. Li[O3SC-
(3Ph-pz)3], C28H21N6O3SLi (528.51): calcd C 63.63, N 15.90, H
4.01, S 6.07; found C 63.12, N 15.71, H 4.39, S 5.91. IR (KBr):
3437 (s), 3060, 2980, 2882 (m br), 1534 (m, ν(C)N)), 1502 (m),
1456 (s), 1398 (m), 1354 (m), 1266 (s br), 1240 (s br), 1077 (s),
1048 (s, ν(S-O)), 888 (m), 866 (s), 760 (s), 698 (s), 643 (s,
ν(C-S)) cm-1. 1H NMR (300 MHz, acetone-d6): 8.22 (d, 3H, JHH
solution of Li(TpmsPh) (78.3 mg, 0.148 mmol) to
a
[Cu(MeCN)4][PF6] solution (55.2 mg, 0.148 mmol) in the same
solvent (10 mL). The reaction mixture was stirred at room
temperature for 10 min and compound (2) precipitated as a white
powder which was collected by filtration, washed with cold
methanol (2 × 5 mL) and dried under vaccum (57 mg, 62%). It is
well soluble in medium polarity solvents like Me2CO, CHCl3 and
CH2Cl2, less soluble in H2O (S25°C ≈ 4 mg·mL-1), MeOH, EtOH,
and DMSO, and insoluble in C6H6 and Et2O. (2), C30H24N7O3SCu
(626.17): calcd C 57.55, N 15.66, H 3.86, S 5.12; found. C 57.36,
N 15.09, H 3.71, S 4.95. IR (KBr): 3571 (s), 3158, 3126, 3060 (m
br), 2930 (m br), 2316 (w br), 1534 (s, ν(C)N)), 1500 (s), 1458
(s), 1372 (m), 1237 (s br), 1045 (s, ν(S-O)), 853 (m), 767 (s), 696
(m), 639 (s, ν(C-S)), 540 (m) cm-1. 1H NMR (300 MHz, acetone-
d6, 298 K): δ 8.07 (s, br, 3H), 7.95 (d, 6H, JHH ) 7.7 Hz, o-H
(Ph)), 7.52-7.43 (m, 9H, m-H and p-H (Ph)), 6.94 (d, 3H, JHH
)
1
2.8 Hz, 4-H (pz)), 2.12 (s, 3H, H3CCN). H NMR (300 MHz,
acetone-d6, 188 K): δ 8.87 (s, br, 1H, 5-H (pz)), 8.09 (d, 4H, JHH
) 7.4 Hz, o-H (Ph)), 7.99 (d, 2H, JHH ) 7.4 Hz, o-H (Ph)),
7.63-7.47 (m, 9H, m-H and p-H (Ph)), 7.35 (s, br, 1H 4-H (pz)),
7.27 (s, br, 2H, 5-H (pz)), 7.00 (s, br, 2H, 4-H (pz)). 13C{1H} and
HMQC 13C-1H NMR (300 MHz, acetone-d6, 298 K): 153.7
(s, 3-C (pz)), 135.8 (s, 5-C (pz)), 131.5 (s, pz-C (Ph)), 129.1 (s,
p-C (Ph)), 128.5 (s, m-C (Ph)), 126.9 (s, o-C (Ph)), 116.18 (s,
NCCH3), 104.71 (s, 4-C (pz)), 100.0 (s, O3SC), 0.91 (s, NCCH3).
(16) (a) Daigle, D. J.; Pepperman, A. B., Jr.; Vail, S. L. J. Heterocycl.
Chem. 1974, 11, 407–408. (b) Daigle, D. J.; Decuir, T. J.; Robertson,
J. B.; Darensbourg, D. J. Inorg. Synth. 1998, 32, 40–45.
(17) (a) Reger, D. L.; Grattan, C. G.; Brown, K. J.; Little, C. A.; Lamba,
J. J. S.; Rheingold, A. L.; Sommer, R. D. J. Organomet. Chem. 2000,
607, 120–128. (b) Reger, D. L.; Collins, J. E.; Jameson, D. L.;
Castellano, R. K.; Canty, A. J.; Jin, H. Inorg. Synth. 1998, 32, 63–65.
10160 Inorganic Chemistry, Vol. 47, No. 21, 2008

Scorpionate Tris(3-phenylpyrazolyl)methanesulfonate Ligand
X-ray quality single crystals were grown by slow evaporation in
air at room temperature of an acetone solution of (2).
br, 2H, 4-H (pz)), 4.39 HA and 4.09 HB (JAB ) 12.0 Hz, 6H,
NCHAHBN (HMT)), 4.19 (s, br, 6H, NcoordCH2N (HMT)). 13C{1H}
and HMQC 13C-1H NMR (75.4 MHz, acetone-d6, 298 K): 153.9
(s, 3-C (pz)), 136.0 (s, 5-C (pz)), 132.47 (s, pz-C (Ph)) 129.7 (s,
p-C (Ph)), 129.2 (s, m-C (Ph)), 127.0 (s, o-C (Ph)), 104.9 (s, 4-C
(pz)), 74.3 (s, br (HMT)). X-ray quality single crystals were grown
by slow evaporation in air at room temperature of the acetone
solution of (4).
Synthesis of [Cu{O3SC(3-Phpz)3}(PTA)], [Cu(TpmsPh)(PTA)], (3).
To a methanolic solution (15 mL) of [Cu(MeCN)4][PF6] (42.0 mg,
0.113 mmol, 1 equiv) was added 5 mL of a solution of Li(TpmsPh)
(60 mg, 0.113 mmol, 1 equiv) in the same solvent. The transparent
colorless solution was stirred for 10 min at room temperature to
allow the formation in situ of complex (2) that remains in solution.
Then PTA (16 mg, 0.10 mmol) was slowly added portionwise and
stirring of the reaction mixture was continued at room temperature
for 1 h. The formed white powder of (3) was collected by filtration,
washed with cold methanol (2 × 10 mL), then recrystallized from
acetone at 4 °C (73.7 mg, 87.5%). Complex (3) is well soluble in
medium polarity solvents like Me2CO, CHCl3 and CH2Cl2, less
soluble in H2O (S25°C ≈ 6 mg·mL-1), MeOH, EtOH and DMSO,
and insoluble in C6H6, and Et2O. (3)·0.5CH2Cl2, C34.5H34ClN9O3-
PSCu (784.74): calcd C 52.80, N 16.06, H 4.36, S 4.08; found C
53.36, N 16.19, H 4.50, S 4.01. IR (KBr): 3168 (s), 2943(m br),
1532 (m, ν(C)N)), 1414 (s), 1328 (m), 1246 (s br), 1054 (s,
ν(S-O)), 1015 (s), 972 (m), 854 (m), 770 (s), 633 (s, ν(C-S)),
Synthesis of [Cu{O3SC(3-Phpz)3}(mPTA)][PF6], [Cu(TpmsPh)-
(mPTA)][PF6], (5). To a stirred methanolic solution (45 mL) of
[Cu(MeCN)4][PF6] (186 mg, 0.50 mmol) were added 10 mL of a
methanolic solution of Li(TpmsPh) (264 mg, 0.50 mmol). After 10
min to allow the formation in situ of [Cu(TpmsPh)(MeCN)] (2) that
remains in solution, a dichloromethane solution (10 mL) of
(mPTA)[BPh4] (246 mg, 0.50 mmol) was added. The reaction
mixture was stirred at room temperature for 1 h and then
concentrated to half-volume under vacuum. The mixture was kept
at 4 °C for 2 days. A white microcrystalline solid was collected,
washed with cold methanol (2 × 10 mL), and dried under vacuum
to yield (5) (315 mg, 70%). Complex (5) is well soluble in medium
polarity solvents like Me2CO, CHCl3, and CH2Cl2, less soluble in
H2O (S25°C ≈ 7.5 mg ·mL-1), MeOH, EtOH, and DMSO, and
insoluble in C6H6 and Et2O. (5) · 1.5CH2Cl2, C36.5H39F6Cl3N9-
O3P2SCu (1029.67): calcd C 42.61, N 12.24, H 3.82, S 3.11; found
C 42.58, N 12.79, H 4.06, S 3.34. IR (KBr): 3651 (s), 3154 (m br),
3107 (m br), 3075 (m br), 2990 (m br), 2930 (m br), 1535 (m,
ν(C)N)), 1450 (m), 1459 (s), 1386 (m), 1355 (m), 1280 (s br),
1247 (s), 1077 (s), 1049 (s, ν(S-O)), 985 (m), 924 (m), 844 (s),
762 (m), 698 (m), 629 (m, ν(C-S)), 558 (m) cm-1. 1H NMR (300
MHz, acetone-d6, 298 K): δ 8.05-7.89 (m, br, 6H+3H, o-H (Ph)
+ 5-H (pz)), 7.61-7.56 (m, 9H, m-H p-H (Ph)), 6.96 (s, br, 3H,
4-H (pz)), 5.01 (s, br, 4H, NCHAHBN+), 4.47 and 4.40 (J(HAHB)
) 14.0 Hz, 2H, NCHAHBN), 3.98 (s, 2H, PCH2N+), 3.61 and 3.43
(J(HAHB) ) 13 Hz, 4H, PCHAHBN), 2.79 (s, 3H, N+CH3). 1H NMR
(300 MHz, acetone-d6, 213 K): δ 8.94 (d, 1H, JHH ) 2.83 Hz, 5-H
1
534 (m) cm-1. H NMR (300 MHz, acetone-d6, 298 K): 8.50 (s,
br, 3H), 7.73 (d, 6H, JHH ) 8.0 Hz, o-H (Ph)), 7.61 (dd, vt, 6H,
m-H (Ph)), 7.54 (dd, vt, 3H, p-H (Ph)), 6.92 (d, 3H, JHH ) 2.8 Hz,
4-H (pz)), 4.16 HA and 3.96 HB (JAB ) 13.0 Hz, 6H, NCHAHBN
(PTA)), 2.97 (s, br, 6H, PCH2N (PTA)). 1H NMR (300 MHz,
acetone-d6, 188 K): δ 8.85 (s, br, 3H, 5-H (pz)), 8.02-7.50 (m,
15H, o-H, m-H and p-H (Ph)), 7.12 (s, br, 3H, 4-H (pz)), 4.09 HA
and 3.72 HB (6H, JAB ) 12.0 Hz, NCHAHBN (PTA)), 2.57 (s, br,
6H, PCH2N (PTA)). 13C{1H} and HMQC 13C-1H NMR (300 MHz,
acetone-d6, 298 K): 154.4 (s, 3-C (pz)), 135.5 (s, 5-C (pz)), 132.3
(s, pz-C (Ph)), 129.33 (s, p-C (Ph)), 129.29 (s, m-C (Ph)), 127.3
(s, o-C (Ph)), 105.6 (s, 4-C (pz)), 72.2 (s, PCH2N), 48.70 (s,
NCH2N). 31P{1H}-NMR (acetone-d6, 298 K): -93.3 (s, br PTA).
X-ray quality single crystals were grown by slow evaporation in
air at room temperature of an acetone solution of (3).
(pz)), 8.04 (d, 4H, JHH ) 7.4 Hz, o-H (Ph)), 7.95 (d, 2H, JHH
)
Synthesis of [Cu{O3SC(3-Phpz)3}(HMT), [Cu(TpmsPh)-
(HMT)], (4). A solution of Li(TpmsPh) (78.3 mg, 0.148 mmol) in
methanol (15 mL) was added to a [Cu(MeCN)4][PF6] solution (55.2
mg, 0.148 mmol) in the same solvent (5 mL). The solution was
7.0 Hz, o-H (Ph)), 7.72-7.58 (m, 6H, m-H (Ph)), 7.52-7.38 (m,
3H, p-H (Ph)), 7.35 (d, 1H, 4-H (pz)), 7.28 (d, JHH ) 2.70 Hz, 2H,
5-H (pz)), 6.96 (d, 2H, 4-H (pz)), 5.08 and 5.00 (J(HAHB) ) 13.0
Hz, 4H, NCHAHBN+), 4.56 and 4.36 (J(HAHB) ) 14.0 Hz, 2H,
NCHAHBN), 4.15 (s, 2H, PCH2N+), 3.78 and 3.20 (J(HAHB) ) 14
Hz, 4H, PCHAHBN), 2.81 (s, 3H, N+CH3). 31P{1H} NMR (121.4
MHz, acetone-d6, 298 K): δ ) -70.9 (br s), -144.2 (septet, PF6).
13C{1H} and HMQC 13C-1H NMR (100.6 MHz, acetone-d6, 298
K): 155.8 (s, 3-C (pz)), 137.2 (s, 5-C (pz)), 130.5 (s, p-C (Ph)),
130.2 (s, m-C (Ph)), 128.3 (s, o-C (Ph)), 106.3 (s, 4-C (pz)), 81.6
(s, NCH2N+), 69.9 (s, NCH2N), 55.8 (s, PCH2N+), 50.1 (s, N+CH3),
46.7 (s, PCH2N). X-ray quality single crystals were grown by slow
evaporation in air at room temperature of an acetone solution of
(5).
stirred for 10 min to allow the formation in situ of [Cu(TpmsPh
-
)(MeCN)] (2) that remains in solution. Then a methanolic solution
(8 mL) of hexamethylenetetramine (HMT) (20.8 mg, 0.148 mmol)
was added to the reaction mixture and the final solution was stirred
at room temperature for 1 h. The white powder of crude (4) was
collected by filtration, washed with cold methanol (2 × 10 mL),
then recrystallized from acetone at 4 °C. The final white microc-
rystalline solid was dried under vacuum to afford (4)·0.5Me2CO
(97 mg, 87%). Complex (4) is well soluble in medium polarity
solvents like Me2CO, CHCl3, and CH2Cl2, less soluble in H2O (S25°C
≈ 6 mg·mL-1), MeOH, EtOH, and DMSO, and insoluble in C6H6
and Et2O. (4)·0.5Me2CO, C35.5H36N10O3.5SCu (754.34): calcd C
56.52, N 18.57, H 4.81, S 4.25; found C 56.24, N 18.23, H 4.63,
S 4.05. IR (KBr): 3571 (s), 3151, 3107, 3070 (m br), 2980 (m br),
2951(m br), 2926(m br), 2883 (m br), 1534 (m, ν(C)N)), 1499
(m), 1457 (s), 1376 (m), 1240 (s br), 1046 (s, ν(S-O)), 1023 (s),
Results and Discussion
1. Syntheses of the Sterically Hindered Scorpionates
TpmPh and Li(TpmsPh). Hydrotris(3-phenylpyrazolyl)-
methane, TpmPh (Figure 1, R) H), was prepared by
modifying Reger’s procedure17a to obtain the pure desired
product without chromatographic purification. Hence, at the
final stages, we have treated a toluene solution of the crude
product with a catalytic amount of trifluoroacetic acid (to
isomerize the mixture of regioisomers to the desired 3-isomer
compound)17b and then triturated the final crude solid in
diisopropyl ether to afford the pure TpmPh compound.
991 (m), 852 (m), 760 (s), 705 (m), 637 (s, ν(C-S)), 533 (m) cm-1
.
1H NMR (300 MHz, acetone-d6, 298 K): δ 7.94 (d, 6H, JHH ) 7.4
Hz, o-H (Ph)), 7.84 (s, br, 3H, 5-H (pz)), 7.60-7.52 (m, 12H, m-H
p-H (Ph)), 6.92 (s, br, 3H, 4-H (pz)), 4.29 (s, br, 12H, NCH2N
1
(HMT)). H NMR (300 MHz, acetone-d6, 188 K): δ 8.91 (s, br,
1H, 5-H (pz)), 8.14 (d, 4H, JHH ) 7.0 Hz, o-H (Ph)), 7.95 (s, br,
2H, o-H (Ph)), 7.76-7.66 (m, 6H, m-H (Ph)), 7.45 (m, 3H, p-H
(Ph)), 7.35 (s, br, 1H, 4-H (pz)), 7.22 (s, br, 2H, 5-H (pz)), 6.90 (s,
Inorganic Chemistry, Vol. 47, No. 21, 2008 10161

Wanke et al.
5-H and 4-H pyrazolyl protons, respectively. TpmPh and its
sulfonate Li(TpmsPh) represent a highly sterically hindered
class of scorpionates. Moreover, the sulfonate derivative
shows interesting properties in terms of solubility. In fact,
in spite of the presence of three phenyl rings, Li(TpmsPh) is
well soluble in all common polar solvents, that is, MeOH,
EtOH, acetone, and water (S25°C ≈ 90 mg ·mL -1), and shows
a decreasing solubility in medium polarity solvents and in
non-polar ones. We have thus started to investigate its
coordination chemistry, as described below.
Figure 1. Schematic structures of the tris(3-phenylpyrazolyl)methane
compounds TpmPh (R ) H) and Li(TpmsPh) (1) (R ) SO3Li).
2. Syntheses of the CuI Complexes [Cu(TpmsPh)L] [L
) MeCN (2), PTA (3), HMT (4)] and [Cu(TpmsPh)-
(mPTA)][PF6] (5). Reaction of Li(TpmsPh) (1) with
[Cu(MeCN)4][PF6] in methanol proceeds readily at room
temperature to give [Cu(TpmsPh)(MeCN)] (2) bearing the
anionic TpmsPh ligand and one bound molecule of acetoni-
trile, in good yield (Scheme 2). The neutral CuI complex
(2) precipitates from the concentrated reaction mixture, as a
white solid, which is sparingly soluble in water (S25°C ≈ 4
mg · mL-1), MeOH, EtOH, or DMSO, and well soluble in
Me2CO, CHCl3, or CH2Cl2. It is stable in air when dried but
is relatively unstable in solution (after 2-3 days the color
changes to green, typical of a CuII oxidized product). It was
characterized, as the compounds (3)-(5) described below,
by NMR and IR spectroscopies, elemental analysis, and
Scheme 1. Synthesis of Tris(3-phenylpyrazolyl)methanesulfonate, as
the Lithium Salt Li(TpmsPh) (1)
Starting from TpmPh we were able to prepare the tris(3-
phenylpyrazolyl)methanesulfonate species as the lithium salt,
Li(TpmsPh) (1) (Figure 1, R ) SO3Li) in good yield,
following a process known10 for the synthesis of other Tpms,
that is, by deprotonation of the methine carbon by BuLi, at
low temperature, followed by sulfonation with the SO3NMe3
adduct (Scheme 1). Both TpmPh and Li(TpmsPh) were
1
X-ray diffraction. The H and 13C NMR and IR spectra of
(2) confirm the presence of its ligands: the NMR shifted
resonances of TpmsPh and an IR weak and broad NC
stretching band at 2316 cm-1, well above that of uncoordi-
nated NCMe, that is, 2253 cm-1. This positive coordination
shift [∆ν(NC)) 63 cm-1] indicates that the acetonitrile is
behaving as a very weak π-acceptor, acting mainly as an
effective σ-donor ligand, in accord with related scorpionate
complexes.18
1
characterized by H, 13C NMR, and IR spectroscopies, and
elemental analyses. As the TpmPh, the sulfonate derivative
shows a well resolved 1H NMR spectrum (acetone-d6) with
only one set of resonances for the three equivalent pyrazolyl
rings: one pattern of signals for the phenyl protons and a
pair of doublets (JHH ) 2.7 Hz) at δ 8.22 and 6.83 for the
Scheme 2. Syntheses of the Complexes [Cu(TpmsPh)L] [L ) MeCN (2), PTA (3), HMT (4)] and [Cu(TpmsPh)(mPTA)][PF6] (5)
10162 Inorganic Chemistry, Vol. 47, No. 21, 2008

Scorpionate Tris(3-phenylpyrazolyl)methanesulfonate Ligand
Treatment of a methanolic solution of (2), formed in situ,
with PTA (0.9 equiv) in methanol leads to the precipitation
of [Cu(TpmsPh)(PTA)] (3), as a white solid isolated in high
yield (88%). This complex shows a good solubility in acetone
and dichloromethane, and it is fairly soluble in water (S25°C
≈ 6 mg·mL-1). The addition of PTA to the reaction mixture
should be slow to yield (3) in high purity. Traces of the
byproduct [Cu(PTA)4][PF6] are formed when the addition
is faster or the phosphine is used in a higher amount,
indicating a stronger coordination ability of PTA to Cu(I)
in comparison with TpmsPh. The formation of [Cu(PTA)4]-
[PF6] is evidenced by the quartet (1JP-Cu ) 760 Hz) resonance
at δ -80 observed by 31P{1H} NMR, which is analogous to
that known19 for [Cu(PTA)4][NO3].
1
In the H NMR spectrum of (3) (acetone-d6), the reso-
nances for the PTA moiety confirm its coordination to copper
and appear shifted to lower field relatively to those of the
free PTA: the six equivalent protons close to the P-atoms
give a broad singlet at δ 2.97, and the other resonances for
the protons near the N-atoms display the expected AB pattern
at δ 3.96-4.16. The TpmsPh resonances are given below.
The 31P{1H} NMR spectrum shows a single broad signal at
δ -93. Further NMR experiments at different temperatures
reveal additional information on the behavior of compound
(3) in solution that will be discussed below. The IR spectrum
confirms the presence of TpmsPh (stretching bands at 1539
(C)N), 1048 (SO) and 643 (CS) cm-1)11d and PTA (1015,
972 and 950 cm-1, full description in the Experimental
Section).
Similarly to the reaction with PTA, the acetonitrile
complex (2) formed in situ reacts with hexamethylenetetra-
mine (HMT) or N-methyl-1,3,5-triaza-7-phosphaadamantane
tetraphenyl borate ((mPTA)[BPh4]) to yield the correspond-
ing complexes [Cu(TpmsPh)(HMT)] (4) or [Cu(TpmsPh)-
1
(mPTA)][PF6] (5) (Scheme 2). The H NMR spectrum of
(4) at 188 K shows two types of methylene protons for the
ligated HMT (i.e., an AB spin system and a broad singlet)
confirming the coordination by one of nitrogen atoms.
However, at room temperature, only a broad singlet is
observed because of an average effect of a dynamic process
(see below, NMR section). The isolation, upon precipitation,
of compound (5), instead of the [BPh4]- analogue, indicates
that the former is less soluble than the latter. As observed
Figure 2. ORTEP plot of [Cu(TpmsPh)(MeCN)] (2), with ellipsoids shown
at 50% probability.
and therefore of the refinement, is very low. The Oak Ridge
Thermal Ellipsoid Plot (ORTEP) plots are depicted in Figures
2-5, the ellipsoids being shown at 50% probability and the
hydrogen atoms being omitted for clarity. Crystallographic
details are given in Table 1, selected bond distances in Table
2, and selected angles in Table 3.
Single crystals of compounds (2) to (4) suitable for X-ray
diffraction were obtained by slow evaporation in air of
acetone solutions. In complexes (2) and (4) (Figures 2 and
3), the anionic tris(3-phenylpyrazolyl)methanesulfonate group
acts as a tridentate ligand with the N,N,O coordination mode
to the Cu ion through the two pyrazolyl nitrogens N(2) and
N(4) and the oxygen O(1) of the sulfonate moiety. The
coordination around each copper is highly distorted tetra-
hedral with the N2-Cu1-N7 and N4-Cu1-N7 angles of
121.02(12)° and 146.62(12)° for (2) or 147.73(14)° and
124.27(14)° for (4), and the O1-Cu1-N7 angle of a much
lower value (109.82(11)° for (2) or 92.38(12)° for (4)).
Moreover, the Cu(1)-O(1) bond length (2.326(2) Å for (2)
for (2), compounds (3)-(5) are soluble in water (S25°C
≈
6-7 mg· mL-1).
3. X-ray Molecular Structures of Complexes
[Cu(TpmsPh)L] [L ) MeCN (2), PTA (3), HMT (4)]
and [Cu(TpmsPh)(mPTA)][PF6] (5). The molecular struc-
tures of compounds (2)-(5) were determined by single
crystal X-ray diffraction experiments. Although the X-ray
diffraction structural analysis of compound 5 confirms the
formulation proposed (see below) the quality of the crystals,
(18) (a) Reger, D. L.; Collins, J. E. Organometallics 1996, 15, 2029–2032.
(b) Conry, R. R.; Ji, G.; Tipton, A. A. Inorg. Chem. 1999, 38, 906–
913.
(19) Kirillov, A. M.; Smolenski, P.; da Silva, M. F. C. G.; Pombeiro, A. J. L.
Eur. J. Inorg. Chem. 2007, 2686–2692.
Inorganic Chemistry, Vol. 47, No. 21, 2008 10163

Wanke et al.
Table 1. Crystallographic Data (150 K) for Compounds [Cu(TpmsPh)(MeCN)] (2), [Cu(TpmsPh)(PTA)] (3), [Cu(TpmsPh)(HMT)] (4), and
[Cu(TpmsPh)(mPTA)][PF6] (5)
(2)
(3)·C3H6O
(4)
(5)·C3H6O
empirical formula
formula weight
crystal system
space group
a (Å)
C30H24CuN7O3S
626.18
C34H33CuN9O3PS. C3H6O
800.36
orthorhombic
Pbca
13.799(3)
20.730(5)
26.676(7)
7631(3)
90
C37H39Cu N10O4S
783.38
orthorhombic
Pbca
11.4692(7)
21.8702(14)
28.7465(16)
7210.6(8)
90
C35H36CuN9O3PS, C3H6O, F6P
960.37
Monoclinic
P21/n
16.056(6)
15.889(6)
16.279(6)
4123(3)
96.901(2)
4
orthorhombic
Pbcn P2n2ab
15.0997(15)
13.9691(14)
28.789(3)
6072.5(11)
90
b (Å)
c (Å)
V (Å3)
ꢀ (deg)
Z
8
8
8
Fcalc (g cm-3
)
1.370
0.831
2576
1.393
0.721
3328
1.443
0.720
3264
1.547
0.738
1976
µ(Mo KR) (mm-1
F (000)
)
refl. collected/unique
goodness-on-fit on F2
R1 [I > 2σ(I)] (all data)
26662/5543
0.938
0.0474 (0.0904)
28366/6974
0.939
0.0615 (0.1721)
35881/6595
0.997
0.0555 (0.1315)
7547/7547
1.284
0.1573 (0.2349)
angles (defining23a the degree of tilting of the rings with
respect to the Cs axis of the molecule) are in the range of
12.3(5)° (in 4) to 22.5(3)° (in 2) (Table 3).
Table 2. Selected Bond Distances [Å] for Compounds
[Cu(TpmsPh)(MeCN)] (2), [Cu(TpmsPh)(PTA)] (3), [Cu(TpmsPh)(HMT)]
(4), and [Cu(TpmsPh)(mPTA)][PF6] (5)
(2)
(4)
(3)·C3H6O (5)·C3H6O
In compounds (3) and (5), the anionic TpmsPh acts as a
tridentate N,N,N-ligand (Figures 4 and 5). The N-Cu-N
angles are restrained by the chelate rings to 84.5(3)°-
89.06(16)°, while the wider N-Cu-P angles are within the
range of 125.24(12)°- 129.9(2)°. In both structures there is
a high degree of tilting of the pyrazolyl rings with the
Cu-N-N-C(1) torsion angles from 29.6(10)° in (5) to
42.2(5)° in (3) being drastically higher than those for other
scorpionate analogues.23b Similarly, we can compare the
Cu-N-N-C (where C is at pyrazolyl) torsion angles,
averaging 133° for (3) and 139° for (5), with their analogues
in the related Cu(I) complexes [Cu{HC(3-tBupz)3}L][PF6]
(L ) CO or NCMe)18a with a maximum torsion angle of
171° (L ) NCMe). In the present structures, the distortion
can tentatively be attributed to steric effects associated to
the phenyl substituent in the pyrazolyl rings and to the PTA
or (mPTA)+ ligands.
Cu(1)-N(2) 2.065(3) 1.968(4) Cu(1)-N(2) 2.170(4)
Cu(1)-N(4) 1.996(3) 2.052(3) Cu(1)-N(4) 2.138(4)
Cu(1)-O(1) 2.326(2) 2.412(2) Cu(1)-N(6) 2.099(4)
C(1)-N(1) 1.458(4) 1.471(5) C(1)-N(1) 1.446(7)
C(1)-N(3) 1.465(4) 1.459(5) C(1)-N(3) 1.465(7)
C(1)-N(5) 1.429(5) 1.434(5) C(1)-N(5) 1.446(7)
2.112(8)
2.099(8)
2.104(8)
1.463(13)
1.464(13)
1.419(13)
Cu(1)-N(7) 1.858(4) 1.956(3) Cu(1)-P(1) 2.1492(15) 2.139(3)
S(1)-O(1) 1.453(3) 1.452(3) C(1)-S(1)
S(1)-O(2) 1.438(2) 1.441(3)
S(1)-O(3) 1.446(2) 1.442(3)
N(7)-C(29) 1.145(6)
1.883(6)
1.893(10)
or 2.412(2) Å for (4)) is significantly longer than the Cu-O
bond in Cu-OSO2 (2.136(6) Å) and Cu-ONO2 (2.110(6)
Å) in Na5[Cu(TPPTS)]·5H2O (TPPTS ) tris(m-sulfonatophe-
nyl)phosphate) and [(Ph3As)3Cu(NO3)], respectively.20,21
However, it is within the sum of their van der Waals radii
and is in accord with other Cu-Tpms complexes.22 In (2)
the Cu(1)-N(7) distance of 1.858 Å is comparable to that
observed in a analogue acetonitrile copper(I) complexes,17
although about 0.1 Å shorter than that found in (4).
Moreover, the solid state structure of compound (5) (Figure
5) exhibits the presence of intramolecular C-H· · ·π interac-
tions specifically between the C(29)-H(22) moiety and the
closest phenyl ring (i.e., C(5-10)). The distance between
the C-H hydrogen and the centroid of this ring is 2.489 Å,
The Cu-N-N-C (where C is at pyrazolyl) torsion angles
of the pyrazolyl rings present values from 150.1(2)° (in 2)
to 179.0(3)° (in 4), whereas the Cu-N-N-C(1) torsion
Table 3. Selected Angles [deg] for Compounds [Cu(TpmsPh)(MeCN)] (2), [Cu(TpmsPh)(PTA)] (3), [Cu(TpmsPh)(HMT)] (4), and
[Cu(TpmsPh)(mPTA)][PF6] (5)
(2)
(4)
(3)·C3H6O
(5)·C3H6O
N2-Cu1-N7
N4-Cu1-N7
O1-Cu1-N7
N2-Cu1-N4
O1-Cu1-N4
O1-Cu1-N2
C1-S1-O1
C1-S1-O3
C1-S1-O2
O2-S1-O1
O2-S1-O3
O3-S1-O1
121.02(12)
146.62(12)
109.82(11)
88.65(11)
86.34(10)
84.26(9)
104.38(16)
103.15(15)
103.51(14)
114.81(15)
115.02(14)
113.95(15)
147.73(14)
124.27(14)
92.38(12)
87.80(14)
86.63(12)
84.99(12)
103.07(16)
104.56(19)
103.32(19)
114.1(2)
N2-Cu1-P1
N4-Cu1-P1
N6-Cu1-P1
N2-Cu1-N4
N4-Cu1-N6
N2-Cu1-N6
125.24(12)
129.05(12)
128.95(13)
85.14(16)
85.06(16)
89.06(16)
127.1(2)
127.8(2)
129.9(2)
86.9(3)
85.5(3)
84.5(3)
Cu1N2-N1C2
Cu1N4-N3C11
Cu1N6-N5C20
Cu1N2-N1C1
Cu1N4-N3C1
Cu1N6-N5C1
138.2(4)
136.1(4)
126.0(4)
32.9(5)
39.1(5)
42.4(5)
137.1(7)
141.8(7)
137.3(7)
36.0(9)
29.6(10)
33.2(10)
115.7(2)
114.04(18)
Cu1N4-N3C11
Cu1N2-N1C2
Cu1N4-N3C1
Cu1N2-N1C1
167.9(2)
150.1(2)
22.5(3)
18.0(3)
179.0(3)
156.0(3)
12.3(5)
18.5(5)
10164 Inorganic Chemistry, Vol. 47, No. 21, 2008

Scorpionate Tris(3-phenylpyrazolyl)methanesulfonate Ligand
Figure 5. ORTEP plot of [Cu(TpmsPh)(mPTA)][PF6] (5), with ellipsoids
shown at 50% probability; hydrogen atoms are shown but the [PF6]-
counterion and one molecule of crystallization acetone are omitted for clarity.
The dashed line indicates the C-H· · ·π intramolecular (2.489 Å) interaction
between C(29)-H(22) and the π-phenyl ring (C(5) to C(10)).
1
Table 4. Selected H-NMR (Acetone-d6) Chemical Shifts (δ) for
Compounds [Cu(TpmsPh)(MeCN)] (2), [Cu(TpmsPh)(PTA)] (3),
[Cu(TpmsPh)(HMT)] (4), and [Cu(TpmsPh)(mPTA)][PF6] (5)
room
temperature (δ)
low temperature
Figure 3. ORTEP plot of [Cu(TpmsPh)(HMT)] (4), ellipsoids are shown
at 50% probability.
compound
limit (δ)
(2)
4-H
5-H
4-H
5-H
4-H
5-H
4-H
5-H
6.94(3H)
8.07(3H)
6.92(3H)
8.50(3H)
6.92(3H)
7.84(3H)
6.96(3H)
c
7.35(1H),7.00 (2H)
8.87(1H),7.27 (2H)
7.12(3H)a
(3)
(4)
(5)
8.85(3H)a
7.35(1H),6.90 (2H)
8.91(1H),7.22 (2H)
7.35(1H),6.96(2H)b
8.94(1H),7.28(2H)b
a With a small amount of N2O-coordination (Keq ) [N3-coordinated
species]/[N2O-coordinated species]) 3.2) at 8.92, 7.35 (for 5-H) and 7.41,
6.97 (for 4-H). b With traces of N3-coordination (Keq ) [N3-coordinated
species]/[N2O-coordinated species]) 0.12) at 8.87 (for 5-H) and 7.08 (for
4-H). c Very broad resonance under the phenyl rings resonances at δ about
8.05-7.90, detected by HMQC 13C-1H NMR.
a sort of symmetrical intramolecular interaction that probably
helps to stabilize the N,N,N-coordination mode, in the solid
state.
In the case of complexes (2) and (4), bearing N-donor
ligands (MeCN and HMT, respectively) that are effective
σ-electron donors and not appreciable π-acceptors, the metal
tends to prefer the weaker electron-donating N2O-coordina-
tion mode of TpmsPh. The stronger electron-releasing N3-
coordination of the latter ligand appears to be the preferable
one for complexes (3) and (5) with π-acceptor phosphine
ligands, in spite of the stronger steric hindrance associated
to this type of coordination in comparison with the N2O-
mode.
Figure 4. ORTEP plot of [Cu(TpmsPh)(PTA)] (3), with ellipsoids shown
at 50% probability; one molecule of acetone is omitted for clarity.
indicating a relatively strong non-covalent interaction.24
Similarly, each of the other two phenyl rings interacts with
the corresponding H atom of a methylene group of (mPTA)+
(although at longer 2.520 and 2.594 Å distances), constituting
(20) Tisato, F.; Refosco, F.; Bandoli, G.; Pilloni, G.; Corani, B. Inorg.
Chem. 2001, 40, 1394–1396.
Inorganic Chemistry, Vol. 47, No. 21, 2008 10165

Wanke et al.
Figure 6. Variable temperature (298-213 K) 1H NMR spectra (selected ppm ranges) for (2) (a) and (3) (b) in acetone-d6. (*) indicates traces of the
N2O-coordination isomer.
4. NMR Solution Studies. The complexes exhibit flux-
ional behavior in solution, as shown by variable temperature
NMR studies (Table 4) which have allowed to check if the
coordination modes of the TpmsPh ligand observed in the
solid state are retained in solution.
equilibrium (1, Scheme 3) between the two coordination
forms. In accord, such a type of Tpms coordination equi-
librium is known11a,b to be temperature dependent.
In contrast, the other complexes ((2), (4), and (5)) display
1
low temperature H NMR limit spectra that are consistent
Hence, compound (3), with the N3-type coordination in
the solid state, as established by X-ray diffraction (see above),
in solution (acetone-d6) at room temperature shows, in the
1H NMR spectrum, the expected resonances for the 4-H and
5-H protons of the three equivalent pyrazolyl rings. This
pattern essentially remains upon cooling until 200 K,
indicating the preservation of the N3-coordination at low
temperature. Only traces of the pattern associated to the N2O-
coordination were then detected (Figure 6b), as a result of
the shift at low temperature, toward this mode, of the
with the N2O-coordination (two equivalent and one non-
equivalent pyrazolyl rings, Figure 6a),11c which is also the
observed one for (2) and (4) in the solid state. In the case of
(5), linkage isomerization (1, Scheme 3) of the N3-mode
exhibited in the solid state has occurred in solution (only
traces of the N3-coordination are detected).
However, at room temperature, all complexes (2)-(5)
display 1H NMR spectra that are indicative of the equivalence
of the three pyrazolyl rings (Table 4). In the case of (3) (see
above), this is conceivably due to the N3-type coordination
10166 Inorganic Chemistry, Vol. 47, No. 21, 2008

Scorpionate Tris(3-phenylpyrazolyl)methanesulfonate Ligand
Scheme 3. Equilibria between the Two Different TpmsPh Coordination Modes for Complexes of General Formula [M(TpmsPh)L]a
a Type A, N3-coordination, C3V-symmetry; type B, N2O-coordination, Cs-symmetry; also shown is the dynamic process among different N2O-coordination
modes.
(form A, Scheme 3) that is retained from the solid state,
whereas for the other complexes ((2), (4), and (5)), it can be
ascribed to the fast equilibria (2, 2′, and 2′′, Scheme 3) among
the three forms (B, B′, and B′′) with N2O-coordination.
Decreasing the temperature leads to a split to a double pattern
with two distinct sets of resonances in the 2:1 ratio (Figure
6a, at 213 K).
The TpmsPh complexes (2) and (4), bearing a N-donor
ligand (MeCN or HMT, respectively), preserve, in solution,
the N2O-coordination observed in solid state, while for
compounds (3) and (5), with a π-acceptor phosphine ligand
(PTA or (MePTA)+, correspondingly), the metal prefers the
stronger electron-releasing N3-coordination mode of TpmsPh.
This argument holds specially for (5), with the cationic
alkylated (mPTA)+ ligand, expected to be, like the protonated
PTA,25 a more effective π-acceptor than PTA in (3). In fact,
the 31P{1H}-NMR signal (δ -70.9) of compound (5) is
shifted to lower field relatively to that (δ -93.3) of complex
(3). Nevertheless, in solution, the less effective electron-donor
N2O-coordination appears to become dominant, which
conceivably results from both steric and electronic effects.
The (mPTA)+ ligand would prefer to avoid the more
sterically demanding TpmsPh N3-binding in accord with the
fact that the molecular structure of (5) (Figure 5), in the solid
state, shows a tilted N3-bound TpmsPh ligand to minimize
the steric interaction between its phenyl rings and (mPTA)+.
Moreover, the cationic phosphine could influence the elec-
trostatic metal interaction with the sulfonate moiety, hamper-
ing the charge separation between the positive metal and the
-
negative SO3 group, thus favoring the N2O-mode.
Conclusions
Tris(3-phenylpyrazolyl)methanesulfonate is a new steri-
cally demanding chelating ligand, and its lithium salt,
Li(TpmsPh), is a convenient starting material for the synthesis
of one-face capping coordination compounds. We have
achieved an easy and powerful synthetic procedure to afford
a new class of CuI complexes bearing this ligand.
It shows the typical tripodal coordination flexibility of
tris(pyrazolyl)methanesulfonate derivatives toward the copper
atom, that is, the N,N,N or N,N,O coordination modes. From
solution NMR and X-ray diffraction experiments we con-
clude that TpmsPh tends to adapt its coordination mode to
the electronic and steric preferences of the metal center. In
fact, compounds (2) and (4), bearing N-donor ligands
(acetonitrile and HMT, respectively) with an expected
stronger electron-donor ability display the N2O coordination,
involving the weak electron-donor sulfonate moiety; whereas
those containing phosphines with a π-acceptor character (i.e.,
(21) Bowmaker, G. A.; Hart, R. D.; de Silva, E. N.; Skelton, B. W.; White,
A. H. Aust. J. Chem. 1997, 50, 553–565.
(22) Santini, C.; Pellei, M.; Lobbia, G. G.; Cingolani, A.; Spagna, R.;
Cavalli, M. Inorg. Chem. Commun. 2002, 5, 430–433.
(23) (a) Frohnapfel, D. S.; White, P. S.; Templeton, J. L. Organometallics
1997, 16, 3737–3750. (b) Reger, D. L.; Gardinier, J. R.; Elgin, J. D.;
Smith, M. D. Inorg. Chem. 2006, 45, 8862–8875.
(24) (a) Janiak, C. J. Chem. Soc., Dalton Trans. 2000, 21, 3885–3896. (b)
Hobza, P.; Havlas, Z. Chem. ReV. 2000, 100, 4253–4264. (c) Mu¨ller-
Dethlefs, K.; Hobza, P. Chem. ReV. 2000, 100, 143–167. (d) Nishio,
M. CrystEngComm 2004, 6 (27), 130–158.
(25) (a) Smolen´ski, P.; Pombeiro, A. J. L. Dalton Trans. 2008, 1, 87–91.
(b) Mebi, C. A.; Frost, B. J. Organometallics 2005, 24, 2339–2346.
(c) Meji, A. M. M.; Otto, S.; Roodt, A. Inorg. Chim. Acta 2005, 358,
1005–1011.
Inorganic Chemistry, Vol. 47, No. 21, 2008 10167

Wanke et al.
compounds (3) and (5)) tend to exhibit the N,N,N capping
coordination that provides a more effective electron-release
to the metal. Moreover, compound (5), bearing the cationic
methylated PTA, shows in solution a good affinity for the
N2O coordination mode, with the bound anionic sulfonate
moiety, lowering the steric interaction between the TpmsPh
and the phosphine.
Acknowledgment. This work has been partially supported
by the Foundation for Science and Technology (FCT), its
POCI 2010 programs (FEDER funded) and the Grants
SFRH/BD/23187/2005 (R.W.) and SFRH/BPD/20869/2004
(P.S.) as well as by the Human Resources and Mobility Marie
Curie Research Training Network (AQUACHEM project,
CMTN-CT-2003-503864).
The complexes described here are soluble in water, and
the flexibility of the new scorpionate ligand, bearing the labile
sulfonate group, provides a good example of a versatile
ligand able to be employed in further reactivity studies,
namely, of metalloenzyme models.
Supporting Information Available: Crystallographic data in
CIF format. This material is available free of charge via the Internet
at http://pubs.acs.org.
IC801254B
10168 Inorganic Chemistry, Vol. 47, No. 21, 2008