Synthesis and coordination chemistry of a new N4-Polydentate class of pyridyl-functionalized scorpionate ligands: Complexes of Fe II, ZnII, NiII, VIV, PdII and use for heterobimetallic systems

Article abstract of DOI:10.1021/ic100966u

The new potentially N₄-multidentate pyridyl-functionalized scorpionates 4-((tris-2,2,2-(pyrazol-1-yl)ethoxy)methyl)pyridine (TpmPy, (1)) and 4-((tris-2,2,2-(3-phenylpyrazol-1-yl)ethoxy)methyl)pyridine (TpmPy ^Ph, (2)) have been synthesized and their coordination behavior toward Fe^II, Ni^II, Zn^II, Cu^II, Pd ^II, and V^III centers has been studied. Reaction of (1) with Fe(BF₄)₂ 6H₂O yields [Fe(TpmPy) ₂](BF₄)₂ (3), that, in the solid state, shows the sandwich structure with trihapto ligand coordination via the pyrazolyl arms, and is completely low spin (LS) until 400 K. Reactions of 2 equiv of (1) or (2) with Zn^II or Ni^II chlorides give the corresponding metal complexes with general formula [MCl₂(TpmPy)₂] (M = Zn, Ni; TpmPy* = TpmPy, TpmPy^Ph) (4-7) where the ligand is able to coordinate through either the pyrazolyl rings (in case of [Ni(TpmPy) ₂]Cl₂ (5)) or the pyridyl-side (for [ZnCl ₂(TpmPy)₂] (4), [ZnCl₂(TpmPy^Ph) ₂] (6) and [NiCl₂(TpmPy^Ph)₂] (7)). The reaction of (1) with VCl₃ gives [VOCl₂(TpmPy)] (8) that shows the N₃-pyrazolyl coordination-mode. Moreover, (1) and (2) react with cis-[PdCl₂(CH₃CN)₂] to give the disubstituted complexes [PdCl₂(TpmPy)₂] (9) and [PdCl ₂(TpmPy^Ph)₂] (10), respectively, bearing the scorpionate coordinated via the pyridyl group. Compounds (9) and (10) react with Fe(BF₄)₂ to give the heterobimetallic Pd/Fe systems [PdCl₂(μ-TpmPy)₂Fe](BF₄)₂ (11) and [PdCl₂(μ-TpmPy^Ph)₂Fe₂(H ₂O)₆](BF₄)₄ (13), respectively. Compound (11) can also be formed from reaction of (3) with cis-[PdCl ₂(CH₃CN)₂], while reaction of (3) with Cu(NO₃)₂ 2.5H₂O generates [Fe(μ-TpmPy) ₂Cu(NO₃)₂](BF₄)₂ (12), confirming the multidentate ability of the new chelating ligands. The X-ray diffraction analyses of compounds (1), (3), (4), (5), and (9) are also reported.

Full text of DOI:10.1021/ic100966u

Inorg. Chem. 2010, 49, 7941–7952 7941
DOI: 10.1021/ic100966u
Synthesis and Coordination Chemistry of a New N4-Polydentate Class of
Pyridyl-Functionalized Scorpionate Ligands: Complexes of
FeII, ZnII, NiII, VIV, PdII and Use for Heterobimetallic Systems
†
Riccardo Wanke, M. Fatima C. Guedes da Silva,†,‡ Stefano Lancianesi,† Telma F. S. Silva,†
´
ꢀ
Luısa M. D. R. S. Martins,†,§ Claudio Pettinari,|| and Armando J. L. Pombeiro*,†
†
´
ꢀ
Centro de Quımica Estrutural, Complexo I, Instituto Superior Tecnico, TU Lisbon, Av. Rovisco Pais,
‡
ꢀ
1049-001 Lisbon, Portugal, Universidade Lusofona de Humanidades e Tecnologias, ULHT Lisbon,
Campo Grande 376, 1749-024 Lisbon, Portugal, Departamento de Engenharia Quımica, ISEL,
§
´
||
´
R. Conselheiro Emıdio Navarro, 1950-062 Lisbon, Portugal, and Dipartimento di Scienze Chimiche,
ꢁ
Universita degli Studi di Camerino, Via S. Agostino 1, 62032 Camerino MC, Italy
Received May 14, 2010
The new potentially N4-multidentate pyridyl-functionalized scorpionates 4-((tris-2,2,2-(pyrazol-1-yl)ethoxy)methyl)-
pyridine (TpmPy, (1)) and 4-((tris-2,2,2-(3-phenylpyrazol-1-yl)ethoxy)methyl)pyridine (TpmPyPh, (2)) have been
synthesized and their coordination behavior toward FeII, NiII, ZnII, CuII, PdII, and VIII centers has been studied. Reaction
of (1) with Fe(BF4)2 6H2O yields [Fe(TpmPy)2](BF4)2 (3), that, in the solid state, shows the sandwich structure with
3
trihapto ligand coordination via the pyrazolyl arms, and is completely low spin (LS) until 400 K. Reactions of 2 equiv
of (1) or (2) with ZnII or NiII chlorides give the corresponding metal complexes with general formula [MCl2(TpmPy*)2]
(M = Zn, Ni; TpmPy* = TpmPy, TpmPyPh) (4-7) where the ligand is able to coordinate through either the pyrazolyl
rings (in case of [Ni(TpmPy)2]Cl2 (5)) or the pyridyl-side (for [ZnCl2(TpmPy)2] (4), [ZnCl2(TpmPyPh)2] (6) and
[NiCl2(TpmPyPh)2] (7)). The reaction of (1) with VCl3 gives [VOCl2(TpmPy)] (8) that shows the N3-pyrazolyl
coordination-mode. Moreover, (1) and (2) react with cis-[PdCl2(CH3CN)2] to give the disubstituted complexes
[PdCl2(TpmPy)2] (9) and [PdCl2(TpmPyPh)2] (10), respectively, bearing the scorpionate coordinated via the pyridyl
group. Compounds (9) and (10) react with Fe(BF4)2 to give the heterobimetallic Pd/Fe systems [PdCl2(μ-TpmPy)2-
Fe](BF4)2 (11) and [PdCl2(μ-TpmPyPh)2Fe2(H2O)6](BF4)4 (13), respectively. Compound (11) can also be formed
from reaction of (3) with cis-[PdCl2(CH3CN)2], while reaction of (3) with Cu(NO3)2 2.5H2O generates [Fe(μ-TpmPy)2-
Cu(NO3)2](BF4)2 (12), confirming the multidentate ability of the new chelating ligands. The X-ray diffraction analyses
of compounds (1), (3), (4), (5), and (9) are also reported.
3
Introduction
of applications in coordination and organometallic chem-
istry.1 The tris(pyrazolyl)methane HCpz3 (pz = pyrazolyl)
(Tpm) ligand has been studied in the past years, and there is a
growing interest to develop its multiple coordination modes.2
In fact, many works report the functionalization of the
central methine carbon atom with groups other than the
hydrogen atom, extending the coordination properties of the
ligand and opening to a variety of applications,3 in particular
in supramolecular chemistry and multimetallic systems. The
polydentate character of such a type of ligands has also been
investigated.4
Within our interest in N-donor ligand chemistry with
scorpionate derivatives,5 we aimed to design new multiden-
tate tris(pyrazolyl)methane ligands bearing an additional
N-donor group pending from the central methine carbon
and to study the role of this extra-unit on their coordination
behavior, namely, focusing on their potential to form hetero-
nuclear species. Hence, we describe the synthesis of the new
Tripodal ligands containing nitrogen-donor heterocycles
linked to a bridging carbon atom are widely used for a variety
*To whom correspondence should be addressed. E-mail: pombeiro@
ist.utl.pt. Fax: þ351-21-846 4455.
(1) (a) Trofimenko, S. J. Am. Chem. Soc. 1966, 88, 1842–1844. (b)
Trofimenko, S. Chem. Rev. 1993, 93, 943–980. (c) Trofimenko, S. Scorpionates:
The Coordination Chemistry of Polypyrazolylborates Ligands; Imperial
College Press: London, 1999. (d) Pettinari, C.; Pettinari, R. Coord. Chem. Rev.
2005, 249, 525–543. (e) Pettinari, C. Scorpionates II: Chelating Borate Ligands;
Imperial College Press: London, 2008. (f) Reger, D. L.; Grattan, T. C. Synthesis
2003, 350–356.
(2) (a) Reger, D. L.; Watson, R. P.; Gardinier, J. R.; Smith, M. D.;
Pellecchia, P. J. Inorg. Chem. 2006, 45, 10088–10097. (b) Reger, D. L.;
Semeniuc, R. F.; Gardinier, J. R.; O'Neil, J.; Reinecke, B.; Smith, M. D. Inorg.
Chem. 2006, 45, 4337–4339. (c) Reger, D. L.; Semeniuc, R. F.; Little, C. A.;
Smith, M. D. Inorg. Chem. 2006, 45, 7758–7769. (d) Reger, D. L.; Gardinier,
J. R.; Bakbak, S.; Semeniuc, R. F.; Buniz, U. H. F.; Smith, M. D. New J. Chem.
2005, 29, 1035–1043. (e) Reger, D. L.; Semeniuc, R. F.; Smith, M. D. J.
Organomet. Chem. 2003, 666, 87–101.
r
2010 American Chemical Society
Published on Web 07/28/2010
pubs.acs.org/IC

7942 Inorganic Chemistry, Vol. 49, No. 17, 2010
Wanke et al.
class of potential tetradentate scorpionates 4-((tris-2,2,2-
(pyrazol-1-yl)ethoxy)methyl)pyridine (TpmPy) (1) and 4-((tris-
2,2,2-(3-phenylpyrazol-1-yl)ethoxy)methyl)pyridine (TpmPyPh)
(2) with an additional pyridyl moiety also able to coordinate.
Therefore, we report herein the coordination chemistry of these
new ligands toward FeII, ZnII, NiII, PdII, and VIII centers, and
their first application as doubly functionalized ligands to the
preparation of heterobimetallic complexes, namely, of FeII/PdII
and FeII/CuII centers.
60% dispersion in mineral oil) is washed with dry pentane (2 ꢀ
10 mL) and then suspended in dry tetrahydrofuran (THF,
15 mL). A THF (20 mL) suspension of tris-2,2,2-(pyrazol-1-
yl)ethanol (482 mg, 1.98 mmol, 1 equiv) and 4-bromomethyl
pyridine hydrobromide (502 mg, 1.98 mmol, 1 equiv) is added
portionwise to the hydride mixture under nitrogen; during this
time, gaseous H2 is formed. The resulting pale brown milky
suspension is refluxed overnight. Then the mixture is allowed
to cool down to room temperature and H2O (20 mL) and Et2O
(20 mL) are added. The organic phase is separated and the
aqueous phase is washed with Et2O (5 mL). The organic phases
are collected, washed with brine, and dried over Na2SO4, where-
after they are filtered and the solvent removed under vacuum to
leave a pale yellow solid that is crystallized in Et2O to give
colorless crystals of (1) (518 mg, 78%). Compound (1) is well
soluble in all common organic solvents, for example, Me2CO,
CHCl3, CH2Cl2, MeOH, EtOH, and dimethyl sulfoxide (DMSO),
Experimental Section
General Materials and Experimental Procedures. All synth-
eses were carried out under an atmosphere of dinitrogen, using
standard Schlenck techniques. All solvents were dried, degassed,
and distilled prior to use. The reagents Fe(BF4)2 6H2O, NiCl2
3
3
6H2O, ZnCl2, 4-bromomethylpyridine hydrobromide (Aldrich),
and vanadium trichloride (Acros) were purchased and used
without further purification. Tris(pyrazolyl)methane, tris-2,2,2-
(pyrazol-1-yl)ethanol, and tris(3-phenyl)pyrazolylmethane were
synthesized in accordance with literature methods.6,5c C, H, and
and less soluble in H2O (S25 °C ≈ 10 mg mL-1). C17H17N7O
3
(335.36): calcd. C 60.88, N 29.23, H 5.10; found C 61.03, N 29.02,
H 5.41. IR (KBr): 3113 (m s), 3041, 2959, 2935 (m s), 2880 (m br),
1601 (s s, ν(CdN)), 1564 (s s, ν(CdN)), 1517 (s s, ν(CdC)), 1426
(m s), 1387 (m br), 1124 (s br), 863 (m s), 753 (s s), 688 (s s), 612 (s s),
N analyses were carried out by the Microanalytical Service of the
ꢀ
1
489 (m s) cm-1. H NMR (300 MHz, CDCl3): δ 8.53 (d, 2H,
-1
Instituto Superior Tecnico. Infrared spectra (4000-400 cm
)
JHH = 6.2 Hz, 2-H (py)), 7.67 (d, 3H, JHH = 2.5 Hz, 5-H (pz)),
7.40 (d, 3H, JHH = 2.5 Hz, 3-H (pz)), 7.06 (d, 2H, JHH = 6.2 Hz,
3-H (py)), 6.36 (dd, 3H, JHH =2.5 Hz, 4-H (pz)), 5.20 (s, 2H, CH2-
were recorded on a BIO-RAD FTS 3000MX instrument in KBr
pellets, and far-infrared spectra (400-200 cm-1) were recorded on
a Vertex 70 spectrophotometer, in polyethylene and cesium iodide
pellets. Vibrational frequencies are expressed in cm-1; abbrevia-
tions (intensity, shape): s, m and w, strong, medium and weak; s
1
C(pz)3), 4.56 (s, 2H, CH2-py). H NMR (MHz, methanol-d4):
δ 8.43 (d, 2H, JHH = 5.7 Hz, 2-H (py)), 7.66 (d, 3H, JHH = 2.5 Hz,
5-H (pz)), 7.50 (d, 3H, JHH = 2.5 Hz, 3-H (pz)), 7.20 (d, 2H,
JHH = 5.7 Hz, 3-H (py)), 6.41 (dd, 3H, JHH = 2.5 Hz, 4-H (pz)),
5.15 (s, 2H, CH2-C(pz)3), 4.64 (s, 2H, CH2-py). 13C{1H} NMR
(100.6 MHz, CDCl3): δ 148.79 (2-C (py)), 145.26 (4-C(py)), 140.46
(3-C(pz)), 129.73 (5-C (pz)), 120.57 (3-C (py)), 105.69 (4-C (pz)),
88.71 (C(pz)3), 73.11 (s, 2H, CH2-C(pz)3), 71.50 (s, 2H, CH2-py).
X-ray quality single crystals were grown by slow cooling to 15 °C of
a concentrated diethyl ether solution of (1).
1
and br, sharp and broad. H, 13C NMR spectra were measured
1
on Bruker 300 and 400 UltraShield spectrometers. H and 13C
chemical shifts δare expressed in parts per million (ppm) relative to
Si(Me)4. Coupling constants are in hertz (Hz); abbreviations: s,
singlet; d, doublet; m, complex multiplet; vt, virtual triplet; br,
broad. EPR spectra were recorded on a Bruker ESP 300E X-band
spectrometer equipped with an ER 4111 VT variable-temperature
unit. ESIþ/ESI- mass spectra were obtained on a VARIAN
500-MS LC ion trap mass spectrometer (solvents: acetonitrile/
methanol; flow: 20 μL/min; needle spray voltage: (5 kV, capillarity
voltage: (100 V; nebulizer gas (N2): 35 psi; drying gas (N2): 10 psi;
drying gas temperature (N2): 350 °C). For the MS spectra descrip-
tion, M denotes the complex part of the compound.
Synthesis of 4-((Tris-2,2,2-(3-phenylpyrazol-1-yl)ethanol,
)
HOCH2C(pzPh
(pzPh = 3-phenyl-pyrazolyl). Tris(3-phenyl-
3
pyrazol-1-yl)methane (300 mg, 0.68 mmol, 1 equiv) is dissolved
in dry THF (8 mL) and potassium tert-butoxide (197 mg, 1.76
mmol, 2.6 equiv) is added portionwise. After 5 min para-
formaldehyde (52 mg, 1.74 mmol, 2.6 equiv) is added and the
resulting mixture stirred at room temperature overnight. Water
(10 mL) is added, and the mixture extracted with diethyl ether
(3 ꢀ 20 mL). The organic extracts are combined, washed with
brine, and dried over sodium sulfate. The mixture is filtered
off, and the solvent is removed in vacuum leading to an off
white powder (286 mg, 89%). The compound is well soluble
in all common organic solvents, for example, Me2CO, CHCl3,
CH2Cl2, MeOH, EtOH, and DMSO, less soluble in H2O.
C29H24N6O (472.55): calcd. C 73.71, N 17.78, H 5.12; found.
C 73.89, N 18.01, H 5.33 IR (KBr): 3056, 2963, 2923 (m s), 2877
(m br), 1544 (m s, ν(CdN)), 1514 (s s, ν(CdC)), 1440 (m s), 1354
(m br), 1137 (s br), 862 (m s), 743 (s s), 648 (m s) cm-1. 1H NMR
(CDCl3): δ 7.83 (d, 6H, JHH = 8 Hz, o-H (Ph)), 7.41 (dd, vt, 6H,
Synthesis of 4-((Tris-2,2,2-(pyrazol-1-yl)ethoxy)methyl)pyri-
dine, TpmPy (1). Sodium hydride (159 mg, 3.98 mmol, 2 equiv,
(3) (a) Reger, D. L.; Semeniuc, R. F.; Little, C. A.; Smith, M. D. Inorg.
€
Chem. 2006, 45, 7758–5569. (b) Klaui, W.; Berghahn, M.; Rheinwald, G.; Lang,
H. Angew. Chem., Int. Ed. 2000, 39, 2464–2466. (c) Reger, D. L.; Semeniuc,
R. F.; Smith, M. D. Inorg. Chem. 2001, 40, 6545–6546. (d) Reger, D. L.; Wright,
T. D.; Semeniuc, R. F.; Grattan, C.; Smith, M. D. Inorg. Chem. 2001, 40, 6212–
6219. (e) Braga, D.; Polito, M.; Bracaccini, M.; D'Addario, D.; Tagliavini, E.;
Proserpio, D. M.; Grepioni, F. Chem. Commun. 2002, 10, 1080–1081. (f) Cotton,
F. A.; Jin, J.-Y.; Li, Z.; Liu, C. Y.; Murillo, C. A. Dalton Trans. 2007, 22, 2328–
2335. (g) Adams, H.; Batten, S. R.; Davies, G. M.; Duriska, M. B.; Jeffery, J. C.;
Jensen, P.; Lu, J.; Motson, G. R.; Coles, S. J.; Hursthoused, M. B.; Ward, M. D.
Dalton Trans. 2005, 1910. (h) Duriska, M. B.; Neville, S. M.; Moubaraki, B.;
ꢀ
Cashion, J. D.; Halder, G. J.; Chapman, K. W.; Balde, C.; Letard, J.-F.; Murray,
K. S.; Kepert, K J.; Batten, S. R. Angew. Chem., Int. Ed. 2009, 48, 2549.
(i) Duriska, M. B.; Neville, S. M.; Lu, J.; Iremonger, S. S.; Boas, J. F.; Kepert, K J.;
Batten, S. R. Angew. Chem., Int. Ed. 2009, 48, 8919.
J
HH = 8 Hz, m-H(Ph)), 7.38 (dd, vt, 3H, JHH = 8 Hz, p-H (Ph)),
7.19 (d, 3H, JHH = 2.6 Hz, 5-H (pz)), 6.67 (dd, 3H, JHH = 2.6
Hz, 4-H (pz)), 5.29 (s, 2H, CH2). 13C{1H} and HMQC 13C-1H
NMR (100.6 MHz, CDCl3): δ 153.68 (s, 3-C (pz)), 132.47 (s, pz-
C (Ph)), 131.78 (s, 5-C (pz)), 128.81 (s, m-C (Ph)), 128.67 (s, p-C
(Ph)), 126.17 (s, o-C (Ph)), 104.16 (s, 4-C (pz)), 90.04 (s, CH2-
C(pz)3), 68.15 (s, O-CH2-C(pz)3).
(4) (a) Rajadurai, C.; Schramm, F.; Brink, S.; Fuhr, O.; Ghafari, M.;
Kruk, R.; Ruben, M. Inorg. Chem. 2006, 45, 10019–10021. (b) Reger, D. L.;
Gardinier, J. R.; Grattan, T. C.; Smith, M. D. J. Organomet. Chem. 2005, 690,
1901–1912. (c) Astley, T.; Canty, A. J.; Hitchmen, M. A.; Rowbootn, G. L.;
Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 1991, 1981–1990.
(5) (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.; Guedes da Silva, M. F. C.; Pombeiro, A. J. L. Organomet. Chem. 2005,
Synthesis of 4-((Tris-2,2,2-(3-phenylpyrazol-1-yl)ethoxy)methyl)-
pyridine, TpmPyPh (2).Sodium hydride (159 mg, 3.98 mmol, 2 equiv,
60% dispersion in mineral oil) is washed with dry pentane (2 ꢀ
10 mL) and then suspended in dry THF (15 mL). A THF (20 mL)
suspension of tris-2,2,2-(3-phenylpyrazol-1-yl)ethanol (940 mg,
1.98 mmol, 1 equiv) and 4-bromomethyl pyridine hydrobromide
(502 mg, 1.98 mmol, 1 equiv) is added portionwise to the hydride
ꢀ
690, 1947–1958. (c) Wanke, R.; Smolenski, P.; Martins, L. M. D. R. S.; Guedes da
Silva, M. F. C.; Pombeiro, A. J. L. Inorg. Chem. 2008, 47, 10158–10168.
(6) 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.

Article
Inorganic Chemistry, Vol. 49, No. 17, 2010 7943
mixture under nitrogen. The resulting pale brown milky suspension
is refluxed overnight. Then the mixture is allowed to cool down to
room temperature, and H2O (20 mL) and Et2O (20 mL) are added.
The organic phase is separated and the aqueous phase is washed
with Et2O (5 mL). The organic phases are collected, washed with
brine, and dried over Na2SO4. Filtration and removal of solvent
under vacuum leaves a transparent oil that is purified by column
chromatography (pentane/acetone 8/2) to give an off white solid
(835 mg, 75%) of (2). Compound (2) is stable in air although being
slightly hygroscopic. It is well soluble in all common organic
solvents, for example, Me2CO, CHCl3, CH2Cl2, MeOH, EtOH,
and DMSO, and is insoluble in H2O. C35H29N7O (563.66): calcd. C
74.58, N 17.39, H 5.19; found. C 74.02, N 16.92, H 5.01. IR (KBr):
3132, 3059, 2923, 2853 (w s, ν(C-H)), 1603 (s s, ν(CdN)), 1561 (s s,
ν(CdN)), 1530 (s s, ν(CdC)), 1499, 1455 (s s), 1219 (m br), 1124,
1101, 1071, 1042 (m s), 869 (s s), 751 (s s), 692 (s s), 616 (w s), 477 (m
s) cm-1. 1H NMR (CDCl3, 298 K): δ 8.47 (d, 2H, JHH = 6.0 Hz,
2,6-H (py)), 7.81 (d, 6H, JHH = 7.6 Hz, o-H (Ph)), 7.57 (d, 3H,
Synthesis of [ZnCl2(TpmPy)2] (4). To a methanolic solution of
ZnCl2 (15 mg, 0.11 mmol, 1 equiv) is added dropwise a solution
of (1) (74 mg, 0.22 mol, 2 equiv) in MeOH. The colorless solution
is stirred at room temperature for 3 h, during which time a white
solid precipitates. The product (4) is filtered off, washed with
a small amount of cold methanol and dried (69 mg, 78%).
The compound (4) is soluble in CHCl3, sparingly soluble in
MeOH, EtOH, acetone, and acetonitrile, insoluble in Et2O
and less soluble in H2O (S25 °C ≈ 2.5 mg mL-1). (4) 2CH3CN
3
3
3
0.5CH2Cl2, C38.5H41Cl3N16O2Zn (931.60) calcd. C 49.63, H
4.43, N 24.06; found. C. 49.62, H 4.23, N 24.06. IR (KBr):
3155, 2930, 2900 (m s, ν(C-H)), 1621 (s s, ν(CdN)), 1563, 1518
(m s, ν(CdN), ν(CdC)), 1430 (s s), 1390 (s s), 1133, 1112 (s s),
869 (m s), 754 (s s), 614 (m s), 508, 478 (m s) cm-1. MS-EI m/z:
434 [ZnCl(TpmPy)]þ, 367 [Zn(TpmPy)2]þ2 1H NMR (300
.
MHz, methanol-d4): δ 8.51 (d, 2H, JHH = 5.7 Hz, 2-H (py)),
7.67 (d, 3H, JHH = 2.5 Hz, 5-H (pz)), 7.50 (d, 3H, JHH = 2.5 Hz,
3-H (pz)), 7.30 (d, 2H, JHH = 5.7 Hz, 3-H (py)), 6.42 (dd, 3H,
J
HH = 2.5 Hz, 4-H (pz)), 5.17 (s, 2H, CH2-C(pz)3), 4.68 (s, 2H,
J
HH =2.6Hz,5-H(pz)),7.40(dd,vt,6H,JHH =7.6Hz,m-H(Ph)),
CH2-py). 1H NMR (300 MHz, acetone-d6): δ 8.67 (d, 2H,
JHH = 5.7 Hz, 2-H (py)), 7.67 (d, 3H, JHH = 2.3 Hz, 5-H
(pz)), 7.56 (d, 3H, JHH = 2.4 Hz, 3-H (pz)), 7.52 (d, 2H, JHH =
7.33 (dd, vt, 3H, JHH = 7.6 Hz, p-H (Ph)), 7.10 (d, 2H, JHH = 6.0
Hz, 3,5-H (py)), 6.67 (d, 3H, JHH = 2.6 Hz, 4-H (pz)), 5.40 (s, 2H,
CH2-C(pz)3), 4.64 (s, 2H, CH2-py). 1H NMR (acetone-d6, 298 K): δ
8.41 (d, 2H, JHH = 5.7 Hz, 2,6-H (py)), 7.86 (d, 6H, JHH = 7.7 Hz,
5.7 Hz, 3-H (py)), 6.41 (dd, vt, 3H, JHH = 2.4 Hz, 4-H (pz)), 5.25
(s, 2H, CH2-C(pz)3), 4.83 (s, 2H, CH2-py). 13C{1H}-NMR
(100.6 MHz, acetone-d6, 298 K): δ 153.04 (s, 4-C (py)), 149.54
(s, 2,6-C (py)), 142.05 (s, 3-C (pz)), 133.70 (s, pz-C (Ph)), 132.16
(s, 5-C (pz)), 123.85 (s, 3,5-C (py)), 107.24 (s, 4-C (pz)), 90.84
(s, CH2-C(pz)3), 74.61 (s, O-CH2-C(pz)3), 72.12 (s, O-CH2-py).
Synthesis of [Ni(TpmPy)2]Cl2 (5). To a water solution of
o-H (Ph)), 7.78 (d, 3H, JHH = 2.7 Hz, 5-H (pz)), 7.40 (t, 6H, JHH
=
7.7 Hz, m-H(Ph)),7.32(t,3H,JHH =7.2Hz,p-H(Ph)),7.19(d,2H,
JHH = 6.0 Hz, 3,5-H (py)), 6.88 (d, 3H, JHH = 2.6 Hz, 4-H (pz)),
5.42 (s, 2H, CH2-C(pz)3), 4.79 (s, 2H, CH2-py). 13C{1H} and
HMQC 13C-1H NMR (100.6 MHz, CDCl3, 298 K): δ 153.08 (s,
3-C (pz)), 149.76 (s, 2,6-C (py)), 146.73 (s, 4-C (py)), 132.81 (s, pz-C
(Ph)), 132.44 (s, 5-C(pz)), 128.70(s, m-C(Ph)), 128.38 (s, p-C(Ph)),
126.03(s, o-C(Ph)), 121.75(s, 3,5-C(py)), 103.88(s, 4-C(pz)), 90.17
NiCl2 6H2O (22 mg, 0.09 mmol, 1 equiv) is added portionwise
3
(1) (61 mg, 0.18 mol, 2 equiv). The solid partially dissolves
during the addition. After addition, the blue-violet solution is
stirred at room temperature overnight, after which time the
solvent is left to evaporate. The product crystallizes from the
concentrated mixture as pale violet crystals that are separated by
filtration (57 mg, 80%). The compound (5) is soluble in CHCl3,
sparingly soluble in MeOH, EtOH, acetone, and acetonitrile,
(s, CH2-C(pz)3), 74.07 (s, O-CH2-C(pz)3), 72.54 (s, O-CH2-py). 13
C
NMR (100.6 MHz, acetone-d6,298K):δ153.47 (s, 3-C (pz)), 150.46
(s, 2,6-C (py)), 147.51 (s, 4-C (py)), 133.72 (s, pz-C (Ph)), 133.65 (s,
5-C (pz)), 129.40 (s, m-C (Ph)), 129.00 (s, p-C (Ph)), 126.52 (s, o-C
(Ph)), 122.38 (s, 3,5-C (py)), 104.43 (s, 4-C (pz)), 90.99 (s, CH2-
C(pz)3), 74.32 (s, O-CH2-C(pz)3), 72.65 (s, O-CH2-py).
insoluble in Et2O and well soluble in H2O (S25 °C ≈ 50 mg mL-1).
Synthesis of [Fe(TpmPy)2](BF4)2 (3). To a methanolic solu-
tion (2 mL) of Fe(BF4)2 6H2O (50 mg, 0.148 mmol, 1 equiv) is
3
(5) H2O C34H36Cl2N14O3Ni (818.35) calcd. C 49.90, H 4.43, N
3
3
23.96; found. C. 49.57, H 4.21, N 24.09. IR (KBr): 2965, 2927 (m s,
ν(C-H)), 1568, 1522 (m s, ν(CdN), ν(CdC)). MS-EI m/z: 364
[Ni(TpmPy)2]þ2. X-ray quality single crystals were grown by slow
evaporation of a concentrated methanol solution of (5).
added portionwise a solution of TpmPy (99 mg, 0.296 mmol,
2 equiv) in MeOH (2 mL). The colorless solution turns imme-
diately to pink and after a few minutes a pink solid precipitates.
The mixture is stirred under nitrogen for 15 min and then
filtered. The solid is washed with methanol (2 ꢀ 5 mL) to leave
a pale pink solid of (3) (120 mg, 91%). Compound (3) is well
soluble in acetonitrile and DMSO, sparingly soluble in CH2Cl2,
Synthesis of [ZnCl2(TpmPyPh)2] (6). To a methanolic solution
of ZnCl2 (15 mg, 0.11 mmol, 1 equiv) is added dropwise a
solution of (2) (124 mg, 0.22 mmol, 2 equiv) in MeOH. An
immediate precipitation of a pale yellow solid occurs. The
mixture is stirred for 10 min, then the solid is filtered off and
washed with a small amount of cold methanol, to yield a pale
yellow solid of (6) (113 mg, 80%). The compound is well soluble
in CHCl3 and acetone, moderately soluble in MeOH, EtOH,
CHCl3, MeOH, and less soluble in H2O (S25 °C ≈ 4.0 mg mL-1).
3
(3) 2CH3CN, C38H40N16O2FeB2F8 (982.30): calcd. C 46.46, N
3
22.81, H 4.10; found. C 46.50, N 22.98, H 3.99. IR (KBr): 3158,
3126, 3060 (m br), 2918 (m br), 1562 (m s, ν(CdN)), 1518 (m s,
ν(CdC)), 1419 (s s), 1341 (s s), 1231 (s br), 1119-1050 (s br,
ν(BF4)), 867 (m s), 770 (s s), 607 (m s), 521 (m s) cm-1. 1H NMR
(CD3CN, 298 K): δ 8.71-8.40 (m, 5H), 7.53 (br s, 2H), 7.39-
7.23 (br m, 3H), 6.57 (br s, 3H), 5.76 (br s, 2H, CH2-C(pz)3), 5.24
and acetonitrile and less soluble in H2O (S25 °C ≈ 0.8 mg mL-1).
3
(6) CH3OH, C71H62Cl2N14O3Zn (1295.66) calcd. C 65.81, H
3
4.82, N 15.13; found. C. 65.74, H 4.67, N 15.31. IR (KBr): 3148,
3060, 2928 (w s, ν(C-H)), 1620 (s s, ν(CdN)), 1531 (m s,
ν(CdC)), 1500 (m s, ν(CdC)), 1456 (s s), 1222 (s br), 871, 776,
694 (s s), 616 (w s), 477 (m s) cm-1. far-IR (Cesium Iodide):
1
(br s, 2H, CH2-py). H NMR (CD3CN, 233 K): δ 8.65-8.60
(m, 24H, 5-H(pz) þ 2,6-H(py)), 8.41 (br s, 6H, 5-H(pz)), 7.53
(d, 12H, JHH = 6.0 Hz, 2,6-H(py)), 7.43 (d, 4H, JHH = 1.6 Hz,
3-H(pz)), 7.40 (d, 2H, JHH = 1.6 Hz, 3-H(pz)), 7.28 (d, 8H,
336-301 cm-1 (m s, ν(Zn-Cl)). MS-EI m/z: 564 [TpmPyPh
þ
JHH = 1.6 Hz, 3-H(pz)), 7.24 (d, 4H, JHH = 1.6 Hz, 3-H(pz)),
H]þ, 662 [ZnCl(TpmPyPh)]þ. 1H NMR (CDCl3, 298 K): δ 8.56
(d, 2H, JHH = 6.0 Hz, 2,6-H (py)), 7.76 (d, 6H, JHH = 7.5 Hz,
o-H (Ph)), 7.44 (d, 3H, JHH = 2.6 Hz, 5-H (pz)), 7.40-7.28 (m,
11H, m-H, p-H(Ph) þ 3,5-H (py)), 6.34 (d, 3H, JHH = 2.6 Hz,
6.55 (m, 6H, 4-H(pz)), 6.52 (m, 12H, 4-H(pz)) 5.73 (br s, 12H,
CH2-C(pz)3), 5.23 (br s,12H, CH2-py). 13C{1H} and HMQC
13C-1H NMR (100.6 MHz, CD3CN, 298 K): δ 153.08 (s,
3-C (pz)), 149.76 (s, 2,6-C (py)), 146.73 (s, 4-C (py)), 132.81 (s,
pz-C (Ph)), 132.44 (s, 5-C (pz)), 128.70 (s, m-C (Ph)), 128.38
(s, p-C (Ph)), 126.03 (s, o-C (Ph)), 121.75 (s, 3,5-C (py)), 103.88
(s, 4-C (pz)), 90.17 (s, CH2-C(pz)3), 74.07 (s, O-CH2-C(pz)3),
72.54 (s, O-CH2-py). X-ray quality single crystals were grown
by slow evaporation under nitrogen, at room temperature, of an
acetonitrile solution of (3).
1
4-H (pz)), 5.40 (s, 2H, CH2-C(pz)3), 4.73 (s, 2H, CH2-py). H
NMR (acetone-d6, 298 K): δ 8.55 (d, 2H, JHH = 6.2 Hz, 2,6-H
(py)), 7.83 (d, 6H, JHH = 7.0 Hz, o-H (Ph)), 7.76 (d, 3H, JHH
2.6 Hz, 5-H (pz)), 7.53 (d, 2H, JHH = 6.0 Hz, 3,5-H (py)), 7.38
(dd, vt, 6H, JHH = 7.6 Hz, m-H (Ph)), 7.31 (dd, vt, 3H, JHH
=
=
7.6 Hz, p-H (Ph)), 6.86 (d, 3H, JHH = 2.6 Hz, 4-H (pz)), 5.47
(s, 2H, CH2-C(pz)3), 4.97 (s, 2H, CH2-py). 13C{1H}-NMR

7944 Inorganic Chemistry, Vol. 49, No. 17, 2010
Wanke et al.
(100.6 MHz, CDCl3, 298 K): δ 153.22 (s, 3-C (pz)), 151.90 (s, 4-C
(py)), 148.46 (s, 2,6-C (py)), 132.46 (s, pz-C (Ph)), 132.27 (s, 5-C
(pz)), 128.79 (s, m-C (Ph)), 128.55 (s, p-C (Ph)), 125.94 (s, o-C
(Ph)), 122.97 (s, 3,5-C (py)), 104.08 (s, 4-C (pz)), 89.91 (s, CH2-
C(pz)3), 74.37 (s, O-CH2-C(pz)3), 71.83 (s, O-CH2-py). 13C
NMR (100.6 MHz, acetone-d6, 298 K): δ 153.69 (s, 3-C (pz)),
153.28 (s br, 4-C (py)), 149.35 (s, 2,6-C (py)), 133.78 (s, pz-C
(Ph)), 132.06 (s, 5-C (pz)), 129.58 (s, m-C (Ph)), 129.19 (s, p-C
(Ph)), 126.66 (s, o-C (Ph)), 123.88 (s, 3,5-C (py)), 104.67 (s, 4-C
(pz)), 90.37 (s, CH2-C(pz)3), 75.14 (s, O-CH2-C(pz)3), 72.40
(s, O-CH2-py).
crystals were grown by slow evaporation of a concentrated
dichloromethane solution of (9).
Synthesis of [PdCl2(TpmPyPh)2] (10). To a dichloromethane
solution (10 mL) of (2) (104 mg, 0.18 mmol, 2 equiv) is added
dropwise a suspension of cis-[PdCl2(CH3CN)2] (24 mg, 0.09
mmol, 1 equiv) in dichloromethane. The pale yellow resulting
solution is stirred at room temperature for 1 h. The solvent is
removed under vacuum, and the residue is washed with a small
amount of cold methanol (2 mL), filtered off, and dried yielding
a pale yellow powder of (10) (80 mg, 68%). The compound is
well soluble in CH2Cl2, CHCl3, CH3CN, and DMSO, moder-
ately soluble in MeOH and EtOH, and insoluble in H2O. (10),
C70H58N14O2PdCl2, (1304.65). calcd. C 65.66, H 2.68, N 15.31.
found: C 65.89, H 2.91, N 15.02. IR (KBr): 3147, 3060, 2925,
2850 (w s, ν(C-H)), 1621 (m s, ν(CdN)), 1531 (s s, ν(CdN),
ν(CdC)), 1500, 1456 (s s), 1221 (s br), 1134, 1102, 1073, 1044 (m
s), 871 (s s), 752 (s s), 694 (s s), 627 (w s), 503 (m s) cm-1. far-IR
(polyethylene): 365 (s s, ν(Pd-Cl). MS-EI m/z: 1268 [PdCl-
(TpmPyPh)2]þ, 1304 [PdCl2(TpmPyPh)2]þ. 1H NMR (CDCl3,
298 K): δ 8.63 (d, 2H, JHH = 6.7 Hz, 2,6-H (py)), 7.81 (d, 6H,
JHH = 7.9 Hz, o-H (Ph)), 7.48 (d, 3H, JHH = 2.6 Hz, 5-H (pz)),
7.41 (dd, vt, 6H, JHH = 7.6 Hz, m-H (Ph)), 7.33 (dd, vt, 3H,
JHH = 7.6 Hz, p-H (Ph)), 7.10 (d, 2H, JHH = 6.6 Hz, 3,5-H
(py)), 6.66 (d, 3H, JHH = 2.6 Hz, 4-H (pz)), 5.40 (s, 2H, CH2-
C(pz)3), 4.64 (s, 2H, CH2-py). 13C{1H} and HMQC 13C-1H
NMR (100.6 MHz, CDCl3, 298 K): δ 153.25 (s, 3-C (pz)), 152.97
(s, 2,6-C (py)), 150.36 (s, 4-C (py)), 132.69 (s, pz-C (Ph)), 132.31
(s, 5-C (pz)), 128.77 (s, m-C (Ph)), 128.47 (s, p-C (Ph)), 126.05 (s,
o-C (Ph)), 122.54 (s, 3,5-C (py)), 104.06 (s, 4-C (pz)), 90.10 (s,
CH2-C(pz)3), 74.56 (s, O-CH2-C(pz)3), 71.79 (s, O-CH2-py).
Synthesis of [PdCl2(μ-TpmPy)2Fe](BF4)2 (11). Method (b,
Scheme 6). To a yellow/brown solution of cis-[PdCl2(CH3CN)2]
(12 mg, 0.046 mmol) in dichloromethane (5 mL) is added
dropwise an acetonitrile solution (5 mL) of [Fe(TpmPy)2]-
(BF4)2 (3) (41 mg, 0.045 mmol, 1 equiv). The resulting mixture
is stirred at room temperature for 1 h, during which time a pale
orange-pink solid precipitates. The solid is filtered off, washed
with acetonitrile and dried, yielding (11) (38 mg, 78%).
Synthesis of [NiCl2(TpmPyPh)2] (7). To a methanolic solution
of NiCl2 6H2O (22 mg, 0.09 mmol, 1 equiv) is added dropwise a
3
solution of (2) (104 mg, 0.18 mmol, 2 equiv) in MeOH. An
immediate precipitation of an off white solid occurs. The
mixture is stirred for 10 min, then the solid is filtered off and
washed with a small amount of cold methanol, to yield (7)
(92 mg, 81%). The compound is well soluble in CHCl3 and acetone,
moderately soluble in MeOH, EtOH, and acetonitrile, and less
soluble in H2O (S25 °C ≈ 1.0 mg mL-1). (7), C70H58Cl2N14O2Ni
3
(1256.92) calcd. C 66.89, H 4.65, N 15.60; found. C. 67.03 H 4.82, N
15.19. IR (KBr): 3148, 3061, 2926 (w s, ν(C-H)), 1617 (s s,
ν(CdN)), 1531 (m s, ν(CdC)), 1500 (m s, ν(CdC)), 1456 (s s),
1221 (s br), 871, 751, 693 (s s), 619 (w s), 489 (m s) cm-1. MS-EIm/z:
564 [TpmPyPh þ H]þ, 656 [NiCl(TpmPyPh)]þ.
Synthesis of [VOCl2(TpmPy)] (8). To a solution of vanadium
trichloride (0.20 g, 1.27 mmol, 1 equiv) in THF (15 mL) is added
(1) (0.430 g, 1.27 mmol, 1 equiv) in THF (10 mL). The resulting
pale blue solution is stirred overnight. The final pale blue
solution is concentrated and upon addition of Et2O a pale blue
solid precipitates. The solid is collected by filtration, washed
with Et2O, and dried in vacuum (313 mg, 52%). The compound
(8) is soluble in DMSO, moderately soluble in MeOH and
EtOH, and less soluble in H2O (S25
≈ 5.0 mg mL-1). (8)
°C
3
VO2Cl2C17H17N7 (473.21) calcd. C 43.15, H 3.62, N 20.72. found:
C 42.92, H 3.53, N 20.81. IR (KBr): 3170, 3148 (s s, ν(C-H)),
1519-1517 (s br, ν(CdC), ν(CdN)), 971 (m, ν(VdO)). far-IR
(polyethylene): 391 and 348 cm-1 (m s, ν(V-Cl)). EPR (DMSO,
r.t.): a = 101.6 G, g = 1.9989. MS-EI m/z: 406 [VOCl2(TpmPy) -
pz]þ, 339 [VOCl2(TpmPy) - 2pz]þ.
Method (b0, Scheme 6). To a dichloromethane solution (8 mL)
of [PdCl2(TpmPy)2] (9) (25 mg, 0.030 mmol) is added dropwise a
solution of Fe(BF4)2 6H2O (10 mg, 0.030 mmol, 1 equiv) in
Synthesis of [PdCl2(TpmPy)2] (9). To a dichloromethane
solution (8 mL) of (1) (78 mg, 0.23 mmol, 2 equiv) is added
dropwise a suspension of cis-[PdCl2(CH3CN)2] (30 mg, 0.11
mmol, 1 equiv) in dichloromethane. The yellow resulting solu-
tion is stirred at room temperature for 1 h, during which time a
pale yellow solid precipitates. The product is filtered off, washed
with a small amount of cold CH2Cl2, and dried, yielding a pale
yellow powder of (9) (70 mg, 75%). The compound is soluble in
CH2Cl2, CHCl3, and DMSO, sparingly soluble in MeOH and
3
methanol. The pale pink resulting mixture is stirred at room
temperature for 1 h. The product is filtered off, washed with a
small amount of methanol, and dried, yielding a pale pink
powder of (11) (23 mg, 69%). (11) 4H2O, C34H42N14B2F8-
3
FeO6PdCl2, (1149.58), calcd. C 35.52, H 3.68, N 17.05 found:
C 35.36, H 3.22, N 17.10. IR (KBr): 3138, 2900 (w s, ν(C-H)),
1621 (s s, ν(CdN)), 1519-1513 (m br, ν(CdN), ν(CdC)), 1420
(s s), 1339 (s s), 1231 (s s), 1106-1036 (s br, ν(BF4)), 866 (m s),
766 (m br) cm-1. MS-EI m/z: 811/813 [PdCl(TpmPy)2]þ, 990
acetonitrile, and less soluble in H2O (S25 °C ≈ 0.8 mg mL-1). (9)
3
1
[{PdCl2(TpmPy)Fe}2(BF4)2]þ2. H NMR (CD3CN, 313 K): δ
C34H34Cl2N14O2Pd, (848.06) calcd. C 48.15, H 4.04, N 23.12.
found. C 48.06, H 3.94, N 23.15. IR (KBr): 3128, 3050, 2923,
2851 (w s, ν(C-H)), 1619 (m s, ν(CdN)), 1561, 1517 (s s,
ν(CdN), ν(CdC)), 1428, 1390 (s s), 1323 (s s), 1133, 1111,
1064 (s s), 867 (s s), 753 (s s), 616 (m s), 505 (m s) cm-1. far-IR
(polyethylene): 361 (m s, ν(Pd-Cl)), 308-296 cm-1 (m s,
8.78 (d, 2H, JHH = 6.0 Hz, 2,6-H (py)), 8.58 (s br, 3H, 5-H (pz)),
7.58 (d, 2H, JHH = 6.0 Hz, 3,5-H (py)), 7.30 (s br, 3H, 3-H (pz)),
6.57 (s, br, 3H, 4-H(pz)), 5.78 (s, 2H, CH2-C(pz)3), 5.31 (s, 2H,
1
CH2-py). H NMR (CD3CN, 253 K): δ 8.72 (d br, 2H, 2,6-H
(py)), 8.62 (s br, 2H, 5-H (pz)), 8.41 (s br, 1H, 5-H (pz)), 7.58 (d
br, 2H, 3,5-H (py)), 7.40 (s br, 1H, 4-H (pz)), 7.27 (s br, 2H, 4-H
(pz)), 6.56 (s, br, 1H, 4-H(pz)), 6.51 (s, br, 2H, 4-H(pz)), 5.78 (s,
2H, CH2-C(pz)3), 5.30 (s, 2H, CH2-py).
1
ν(Pd-Cl)). MS-EI m/z: 811 [Pd(TpmPy)2Cl]þ. H NMR (300
MHz, CDCl3, 298 K): δ 8.68 (d, 2H, JHH = 6.7 Hz, 2,6-H (py)),
7.67 (s, vd, 3H, 5-H (pz)), 7.34 (d, 3H, JHH = 2.6 Hz, 3-H (pz)),
7.07 (d, 2H, JHH = 6.0 Hz, 3,5-H (py)),), 6.36 (m, vdd, 3H, 4-H
(pz)), 5.22 (s, 2H, CH2-C(pz)3), 4.61 (s, 2H, CH2-py). 13C{1H}-
NMR (100.6 MHz, CDCl3, 298 K): δ 153.11 (s, 2,6-C (py)),
150.25 (s, 4-C (py)), 141.75 (s, 3-C (pz)), 130.77 (s, 5-C (pz)),
122.54 (s, 3,5-C (py)), 107.01 (s, 4-C (pz)), 89.85 (s, CH2-C(pz)3),
74.72 (s, O-CH2-C(pz)3), 71.78 (s, O-CH2-py). 13C{1H}-NMR
(100.6 MHz, DMSO-d6, 298 K): δ 152.61 (s, 2,6-C (py)), 150.75
(s, 4-C (py)), 141.01 (s, 3-C (pz)), 131.15 (s, 5-C (pz)), 122.60
(s, 3,5-C (py)), 106.57 (s, 4-C (pz)), 89.17 (s, CH2-C(pz)3), 73.16
(s, O-CH2-C(pz)3), 70.30 (s, O-CH2-py). X-ray quality single
Synthesis of [Fe(μ-TpmPy)2Cu(NO3)2](BF4)2 (12). To an
acetonitrile solution (5 mL) of [Fe(TpmPy)2](BF4)2 (3) (89 mg,
0.1 mmol, 1 equiv), a solution of Cu(NO3)2 2.5H2O (23 mg,
3
0.1 mmol, 1 equiv) in acetonitrile (2 mL) is added. An immediate
precipitation of a pale violet solid occurs. It is filtered off under
nitrogen, washed with a small amount of cold acetonitrile
(1 mL) and dried to leave compound (12) (75 mg, 69%). (12)
3
2H2O, C34H38N16B2CuF8FeO10 (1119.27), calcd. C 36.34, H
3.40, N 19.94. found: C 36.47, H 3.30, N 20.02. IR (KBr): ν =
3137 (m s, C-H), 1620 (m s, ν(NdC)), 1517-1515 (m br,

Article
Inorganic Chemistry, Vol. 49, No. 17, 2010 7945
Table 1. Crystallographic Data for Compound TpmPy (1), [Fe(TpmPy)2](BF4)2 (3), [ZnCl2(TpmPy)2] (4), [Ni(TpmPy)2]Cl2 (5), and [PdCl2(TpmPy)2] (9)
1
3
4
5
9
crystal shape
block
white
block
red
cube
colorless
prism
pink
plate
colorless
empirical formula
formula weight
crystal system
space group
C17H17N7O
335.38
triclinic
P1
8.3750(11)
9.6879(11)
10.6197(14)
92.074(7)
106.285(8)
91.599(7)
825.88(18)
2
1.349
0.091
352
18468
4997
0.031
0.999
R1 = 0.0425
wR2 = 0.1094
R1 = 0.0572
wR2 = 0.1200
C34H34FeN14O2 2(BF4)
900.22
monoclinic
P21/c
14.8596(12)
13.0034(10)
20.7112(17)
90.00
105.932(3)
90.00
3848.2(5)
4
1.554
0.485
1840
24714
6808
0.1116
0.912
C34H34Cl2N14O2Zn
807.02
monoclinic
P21/c
20.5210(12)
15.8868(17)
11.0942(12)
90.00
92.334(3)
90.00
3613.9(6)
4
1.483
0.882
1664
26666
7610
0.057
1.021
C34H34N14NiO2
729.46
monoclinic
P21/c
13.126(11)
22.194(18)
20.15(2)
90.00
104.03(4)
90.00
5695(9)
4
0.851
0.374
1520
43838
12516
0.098
0.847
C34H34Cl2N14O2Pd
848.05
monoclinic
P21/c
13.266(3)
9.2463(19)
16.451(3)
90.00
111.280(7)
90.00
1880.3(7)
2
1.498
0.688
864
12587
3233
0.1462
1.081
˚
a (A)
˚
b (A)
˚
c (A)
R
β
γ
3
˚
V (A )
Z
F
calc (g cm-3
)
μ(Mo KR) (mm-1
F (000)
)
reflections collected
reflections unique
Rint
goodness-of-fit on F2 a
final R indices [I > 2σ(I)]b
R1 = 0.0618
wR2 = 0.1574
R1 = 0.1324
wR2 = 0.2117
R1 = 0.0374
wR2 = 0.0880
R1 = 0.0641
wR2 = 0.1068
R1 = 0.0675
wR2 = 0.1608
R1 = 0.1464
wR2 = 0.1806
R1 = 0.0827
wR2 = 0.1817
R1 = 0.2602
wR2 = 0.2787
R indices (all data)
P
P
P
P
a Refinement Method: Full-matrix least-squares on F2. b R1 = ||Fo| - |Fc||/ |Fo|. wR2 = [ w(Fo2 - Fc2)2/ w(Fo2)2]1/2
.
Scheme 1. Possible Coordination Pathways of TpmPy* (TpmPy (1)
for R = H; TpmPyPh (2) for R = Ph)
ν(NdC), ν(CdC)), 1384 (s s), 1107 (m s), 1082 (m s), 1035 (s s), 866
(s s), 767 (m s), 606 (w s) cm-1. MS-EI m/z: 731 [{Fe(TpmPy)2-
Cu2(TpmPy)}(BF4)(NO3)3]þ2, 363 [Fe(TpmPy)2]þ2
Synthesis of [PdCl2(μ-TpmPyPh)2Fe2(H2O)6](BF4)4 (13). To
an acetonitrile suspension (7 mL) of [PdCl2(TpmPyPh)2] (10)
(30 mg, 0.023 mmol, 1 equiv) is added dropwise a solution of
Fe(BF4)2 6H2O (8 mg, 0.024 mmol, 1 equiv) in acetonitrile. The
3
yellow resulting mixture is stirred at room temperature for
1 h, during which time a pale yellow solid precipitated. The
product is filtered off, washed with a small amount of aceto-
nitrile and dried, yielding a pale yellow powder of (13) (23 mg,
59%). (13) 2((CH3)2CO) 0.5CH3CN, C77H83.5N14.5B2F8Fe2-
3
3
O10PdCl2, (1834.72). calcd. C 50.40, H 4.59, N 11.07. found: C
50.33, H 4.87, N 11.02. IR (KBr): 3441 (w s, ν(OH)), 3147, 3058,
2924 (w s, ν(C-H)), 1643 (w br, δ(OH)), 1620 (m s, ν(CdN)),
1531 (s s, ν(CdN), ν(CdC)), 1499, 1455 (s s), 1429, 1392 (m s),
1220 (s br), 1134, 1133-1043 (s br, ν(BF4)), 871 (s s), 750 (s s),
693 (s s) cm-1. MS-EI m/z: 1268 [PdCl(TpmPyPh)2]þ, 1366
(λ = 0.71073) radiation. Data were collected using ω scans of
0.5° per frame and full sphere of data were obtained. Cell parameters
were retrieved using Bruker SMART software and refined using
Bruker SAINT7a on all the observed reflections. Absorption
corrections were applied using SADABS.7a Structures were
solved by direct methods by using the SHELXS-97 package7b
and refined with SHELXL-97.7c Calculations were performed
using the WinGX System-Version 1.80.03.7d All hydrogen
atoms were inserted in calculated positions. Least-squares
refinements with anisotropic thermal motion parameters for
all the non-hydrogen atoms and isotropic for the remaining
atoms were employed. For (5) there is disordered solvent in the
structure. Attempts were made to model it, but were unsuccess-
ful. PLATON/SQUEEZE7e was used to correct the data.
Crystal data and refinement parameters are shown in Table 1.
CCDC numbers 776297 to 776301 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from the Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
1
[PdCl(TpmPyPh)2Fe](CH3CN)þ. H NMR (CDCl3, 298 K): δ
8.61 (d, 2H, JHH = 6.4 Hz, 2,6-H (py)), 7.78 (d, 6H, JHH = 7.6
Hz, o-H (Ph)), 7.46 (d, 3H, JHH = 2.6 Hz, 5-H (pz)), 7.40 (dd, vt,
6H, JHH = 7.6 Hz, m-H (Ph)), 7.33 (dd, vt, 3H, JHH = 7.6 Hz,
p-H (Ph)), 7.11 (d, 2H, JHH = 6.6 Hz, 3,5-H (py)), 6.65 (d, 3H,
JHH = 2.6 Hz, 4-H (pz)), 5.40 (s, 2H, CH2-C(pz)3), 4.67 (s, 2H,
CH2-py). 13C{1H} and HMQC 13C-1H NMR (100.6 MHz,
CDCl3, 298 K): δ 153.34 (s, 3-C (pz)), 153.07 (s, 2,6-C (py)),
149.91 (s, 4-C (py)), 132.76 (s, pz-C (Ph)), 132.39 (s, 5-C (pz)),
128.82 (s, m-C (Ph)), 128.53 (s, p-C (Ph)), 126.12 (s, o-C (Ph)),
122.62 (s, 3,5-C (py)), 104.12 (s, 4-C (pz)), 89.25 (s, CH2-C(pz)3),
73.92 (s, O-CH2-C(pz)3), 70.89 (s, O-CH2-py).
Crystal Structure Determinations. Single crystals of TpmPy (1),
[Fe(TpmPy)2](BF4)2 (3), [ZnCl2(TpmPy)2] (4), [Ni(TpmPy)2]Cl2
(5), and [PdCl2(TpmPy)2] (9) were obtained as indicated above.
Intensitydatawere collectedat150K, usingaBrukerAXS-KAPPA
APEX II diffractometer with graphite monochromated Mo-KR
(7) (a) APEX2 & SAINT. Bruker, AXS Inc.: Madison, WI, 2004. (b)
Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467. (c) Sheldrick,
G. M. Acta Crystallogr., Sect. A 2008, A64, 112–122. (d) Farrugia, L. J. J. Appl.
Crystallogr. 1999, 32, 837. (e) Spek, A. L. Acta Crystallogr., Sect. C 1990, 46,
C34.
Results and Discussion
We investigatedpossible coordination pathways to explore
the versatility of these new ligands (Scheme 1): on the one

7946 Inorganic Chemistry, Vol. 49, No. 17, 2010
Wanke et al.
Scheme 2. Synthesis of the N4-Scorpionates TpmPy (1) and TpmPyPh (2)
of the pyrazolyl rings, respectively) and, in the case of (2),
one pattern of signals for the phenyl protons (δ 7.81, 7.40,
and 7.33 for the ortho, meta, and para protons, res-
pectively). The resonances of the pyridyl ring protons
appear as a pair of doublets (JHH = 6.0 Hz) at δ 8.53 and
7.06 for (1) and at δ 8.47 and 7.10 for (2).
Compound (1) is well soluble in all common organic
solvents (i.e., Et2O, CH2Cl2, CH3Cl, MeOH, EtOH,
and acetone) and moderately soluble in water (S25 °C
≈
10 mg mL-1) as a free base, while upon protonation of
3
the pyridine nitrogen becomes well water-soluble as a salt.
Compound (2) is not soluble in water, but is soluble in
the usual organic solvents (i.e., Et2O, CH2Cl2, CH3Cl,
MeOH, acetonitrile, and acetone). Compounds (1) and
(2) represent a new type of N4-scorpionate derivatives,
bearing not only the common three pyrazolyl rings but
also one pyridyl group, thus possibly being able to bind
different metal centers, with distinct affinities to the
N-pyrazolyl and the N-pyridyl donor sites, allowing also
to investigate their competition for such N-ligating func-
tions. TpmPyPh (2), being sterically hindered on the
pyrazolyl-side, should be an important candidate to the
synthesis of half-sandwich complexes with metals that
normally would form the full sandwich complex with two
tridentate scorpionate ligands.8
Figure 1. ORTEP plot of TpmPy (1), ellipsoids are shown at 50% of
probability. Hydrogen atoms are omitted for clarity.
hand, we studied the coordination chemistry of the tripodal
“scorpionate” face of the ligand (step (a)); on the other hand,
we explored the reactivity of the pyridyl moiety of the new
ligands toward metal centers known to have a good affinity
for pyridine (step (a0)). The following steps ((b) and (b0))
would account for the further coordination ability of the
ligand toward the synthesis of heterobimetallic systems.
1. Syntheses and Characterization of the New Scorpio-
nates TpmPy and TpmPyPh. We were able to synthesize
4-((tris-2,2,2-(pyrazol-1-yl)ethoxy)methyl)pyridine (TpmPy
(1); Scheme 2, R = H) in good yield by using Tpm as a
starting material, by following a two-step synthetic process.
From a known6 functionalization of Tpm that provides tris-
2,2,2-(pyrazol-1-yl)ethanol, we have reacted the latter, upon
deprotonation with sodium hydride, with 4-bromomethyl-
pyridine to obtain the desired compound. The reaction
proceeds easily and gives (1) in good purity, without the
need of chromatographic purification.
2.1. Reaction of TpmPy (1) with FeII: Synthesis and
Characterization of [Fe(TpmPy)2](BF4)2 (3). FeII is a
metal ion with one of the highest affinities for scorpio-
nates and tends to form full sandwich complexes.9 Accor-
dingly, reaction of 2 equiv of TpmPy (1) with Fe(BF4)2
3
6H2O in methanol proceeds readily at room temperature
to give [Fe(TpmPy)2](BF4)2 (3) bearing two ligated
TpmPy (Scheme 3).
Compound (3) is moderately soluble in CH2Cl2, MeOH,
DMSO, and DMF, and is well soluble in acetonitrile.
Similarly, we prepared the “bulky” analogue bearing
phenyl groups as substituents at the 3-position of the
pyrazolyl rings (TpmPyPh (2); Scheme 2, R = Ph). Com-
pound (2) can be easily purified by column chromato-
graphy at the final stage.
(8) (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.
€
(9) (a) Gutlich, P. In Mossbauer Spectroscopy Applied to Inorganic
1
These products have been characterized by H, 13C
Chemistry; Long, G. J., Ed.; Plenum: New York, 1984; Vol. 1: p 287. (b) G€utlich,
P.; Hauser, A.; Spiering, H. Angew. Chem., Int. Ed. 1994, 33, 2024–2054. (c)
Kahn, O.; Martinez, C. J. Science 1998, 279, 44–48. (d) Muller, R. N.; Van der
Elst, L.; Laurent, S. J. Am. Chem. Soc. 2003, 125, 8405–8407. (e) Reger, D. L.;
Little, A. C.; Rheingold, A. L.; Lam, M.; Liable-Sands, L. M.; Rhagitan, B.;
Concolino, T.; Mohan, A.; Long, G. J.; Briois, V.; Grandjean, F. Inorg. Chem.
2001, 40, 1508–1520. (f) Reger, D. L.; Little, A. C.; Young, V. G.; Maren, P.
Inorg. Chem. 2001, 40, 2870–2874. (g) Reger, D. L.; Gardiner, J. R.; Elgin, J. D.;
Smith, M. D. Inorg. Chem. 2006, 45, 8862–8875. (h) Batten, S. R.; Bjernemose,
J.; Jensen, P.; Leita, B. A.; Murray, K. S.; Moubaraki, B.; Smith, J. P.; Toftlund, H.
Dalton Trans. 2004, 3370–3375. (i) Reger, D. L.; Elgin, J. D.; Foley, E. A.;
Smith, M. D.; Grandjean, F.; Long, G. J. Inorg. Chem. 2009, 48, 9393–9401.
(j) Sheets, J. R.; Schultz, F. A. Polyhedron 2004, 23, 1037–1043.
NMR, and IR spectroscopies, elemental analyses and,
in the case of (1), also by X-ray diffraction analysis;
its molecular structure is depicted in Figure 1. In this
respect, the most striking feature of (1) is the small
O-Cmethylene-Cipso-Cortho torsion angle (118.31°, see
Table 2) which widens considerably upon coordination
(see below). Both compounds (1) and (2) exhibit well
1
resolved H NMR spectra (CDCl3) with only one set of
resonances for the three equivalent pyrazolyl rings (δ 7.67
and 6.36 for (1) or δ 7.57 and 6.67 for (2), for 5-H and 4-H

Article
Inorganic Chemistry, Vol. 49, No. 17, 2010 7947
Scheme 3. Synthesis of [Fe(TpmPy)2](BF4)2 (3)
It forms a pink powder and purple single crystals, as usual
for low spin (LS) FeII scorpionates at room temperature.9
Studies of the spin transition properties of related FeII-Tpm
complexes, such as [Fe(Tpm)2](BF4)2, [Fe(TpmMe2)3)2]-
(BF4)2 (TpmMe2 = tris(3,5-dimethylpyrazolyl)methane),
and their borate analogues [Fe(Tp)3)2](BF4)2 (Tp = tris-
(pyrazolyl)borate), [Fe(TpMe2)3)2](BF4)2, (TpMe2 = tris(3,5-
dimethylpyrazolyl)borate), have been reported, indicating
that complexes of this type show a temperature dependence
spin crossover.9d-f Compound (3) is LS in the solid state and
in solution at room temperature and keeps this spin state
upon heating (to 400 or 325 K, respectively); its solution 1H
NMR spectrum (CD3CN) at room temperature (298 K)
appears as a typical one for a diamagnetic complex, and
increasing the temperature until 325 K does not lead to any
relevant modification, in contrast with what is observed for
the tris(pyrazolyl)methane analogue [Fe(Tpm)2](BF4)2
which shows an electronic spin transition from LS (S = 0)
to HS (S = 2), in solution, above 223 K.9d For the latter
compound, the LS state in the solid state at room tempera-
ture starts to change to the HS state upon heating above
295 K, whereas in solution at room temperature it shows the
contemporary presence of LS and HS.
These different behaviors should be accounted for by
the differences between the ligands (i.e., Tpm and TpmPy).
The pyridyl moiety, as possible competing coordination
site, could influence, in solution, the electronic state of the
metal. In fact, variable temperature 1H NMR experiments
(CD3CN) of (3) allow to distinguish all the resonances. The
analysis of the complex pattern of resonances, through two-
1
1
dimensional NMR experiments (i.e., H-COSY, H/
13C-HSQC and HMBC), indicates the unequivalence of the
three pyrazolyl rings and suggests the competition of the
pyridyl ring, in solution, for the iron center.
The solid-state structure of (3) has been determined by
single crystal X-ray diffraction analysis and consists of
two crystallographically independent molecules, each one
with the TpmPy coordinated through the three pyrazolyl
rings, leaving uncoordinated the pyridyl moieties (Figure 2,
and Tables 1 and 2). The conformations of the pyridine
arms differ in the molecules of (3). While those of Fe2
practically lay in one pyrazolyl plane of the molecule, as
confirmed by the value of the O-Cmethylene-Cipso-Cortho
torsion angle of 176.76°, those of Fe1 are considerably
deviated having such a torsion angle of 166.66° (see
Table 2 and Supporting Information, Figure S.3),
although not as low as that of the free ligand (see above).
Such a peculiarity apparently affects the Fe-N-N-C
torsion angles, which are in the 171.90-178.05° range for
Fe1 and in a narrower one (174.21-177.10°) for Fe2. As
reported for other systems,9e the minimum degree of
tilting of the pyrazolyl rings from an ideal C3v axis is
typical for FeII-Tpm, LS, sandwich complexes: the
Fe-N-N-C torsion angles, in an ideal case, would be
180° and the metal atom would reside in the planes
defined by the pyrazolyl rings; for compound (3) the
indicated angles confirm the pure LS electronic state of
the FeII center.

7948 Inorganic Chemistry, Vol. 49, No. 17, 2010
Wanke et al.
Figure 2. ORTEP plot of the Fe1 molecule in [Fe(TpmPy)2](BF4)2 (3), where the ellipsoids are shown at 50% of probability. The hydrogen atoms and the
tetrafluoroborate counterions are omitted for clarity. Symmetry operation to generate equivalent atoms: 2-x, -y, 1-z.
Scheme 4. Syntheses of [MCl2(TpmPy*)2] (M = NiII, ZnII; TpmPy* =
TpmPy, TpmPyPh) (4-7) and [VOCl2(TpmPy)] (8). Pyridyl-Coordination:
(4), (6), (7); Pyrazolyl-Coordination: (5), (8)
The observed intermolecular π-π interactions in (3)
are also affected by the different conformations of the two
Figure 3. ORTEP plot of [ZnCl2(TpmPy)2] (4), ellipsoids are shown at
molecules. Indeed, in the Fe1 molecules, the pyridyl rings
50% of probability. Hydrogen atoms are omitted for clarity.
and vicinal pyrazol rings interact with centroid/centroid
˚
distances of 3.510 A and the ring planes make angles of
5.11°; conversely, in the molecules of Fe2, such type of
interactions leads to centroid/centroid distances of 3.843
coordination of one or two scorpionates via the pyr-
azolyl rings, but the competition of the pyridyl arm for
the metal can also occur in view of the known11 metal
affinity for this group.
˚
A and angles of 11.41° between the ring planes (see
Supporting Information, Figure S.4). These interactions
could stabilize the packing and the coordination mode
through the three pyrazolyl rings.
Reaction of 2 equiv of TpmPy (1) with ZnCl2 in methanol
affords [ZnCl2(TpmPy)2] (4) (Scheme 4). The compound is
well soluble in CH2Cl2 and sparingly soluble in MeOH and
EtOH. The ESI-MS spectrum shows ionic fragments corres-
2.2. Reactions of TpmPy (1) and TpmPyPh (2) with NiII,
ZnII, and VIII: Syntheses and Characterizations of [MCl2-
(TpmPy*)2] (M = NiII, ZnII; TpmPy* = TpmPy, TpmPyPh)
(4-7) and [VOCl2(TpmPy)] (8). Reactions of (1) and (2)
with ZnII or NiII metal salts can, in principle, give full-
or half-sandwich complexes10 through the tripodal
ponding to [ZnCl(TpmPy)]þ and [Zn(TpmPy)2]2þ
.
The X-ray diffraction analysis of the solid-state structure
of (4) shows a metal tetrahedral-type coordination with
the two TpmPy ligands binding through the pyridyl rings,
whereas the pyrazolyl groups remain uncoordinated
(Figure 3, Tables 1 and 2). This mode of TpmPy coordina-
1
(10) (a) Zvargulis, E. S.; Buys, I. E.; Hambley, T. W. Polyhedron 1995, 14,
2267–2273. (b) Supuran, C. T.; Claramunt, R. M.; Lavandera, J. L.; Elguero, J.
Biol. Pharm. Bull. 1996, 19, 1417–1422. (c) Titze, C.; Hermann, J.; Vahrenkamp,
H. Chem. Ber. 1995, 128, 1095–1103. (d) Trofimenko, S. J. Am. Chem. Soc.
1970, 92, 5118–5126. (e) Reger, D. L.; Little, C. A.; Smith, M. D.; Long, G. J.
Inorg. Chem. 2002, 41, 4453–4460. (f) Astley, T.; Gulbis, J. M.; Hitchman, M. A.;
Tiekink, E. R. T. J. Chem. Soc., Dalton Trans. 1993, 509–515. (g) Hammes,
B. S.; Carrano, C. J. Inorg. Chem. 1999, 38, 3562–3568.
(11) (a) Steffen, W. L.; Palenik, G. J. Inorg. Chem. 1977, 16, 1119–1127.
Blackmore, I. J.; Gibson, V. C.; Hitchcock, P. B.; Rees, C. W.; Williams, D. J.;
White, A. J. P. J. Am. Chem. Soc. 2005, 127, 6012–6020. (b) Westerhausen, M.;
Kneifel, A. N.; Kalish, A. Angew. Chem., Int. Ed. 2005, 44, 96–98. (c) Bacchi,
A.; Bosetti, E.; Carcelli, M. CrystEngComm 2007, 9, 313–318. (d) Long, G. J.;
Clarke, P. J. Inorg. Chem. 1978, 17, 1394–1401. Wu, C. D.; Zhang, L.; Lin, W.
Inorg. Chem. 2006, 45, 7278–7285.
tion is preserved in solution. In fact, in the H NMR
spectrum, the pyridyl resonances are shifted to lower field
(by ca. 0.1 ppm) relatively to those of the free ligand (i.e.,
8.51, 7.30 for (4) and 8.43, 7.20 for (1), in methanol-d4,
corresponding to 2,6-H and 3,5-H of the pyridyl ring, res-
pectively), whereas the pyrazolyl resonances remain almost
unchanged. Moreover, NMR experiments at variable tem-
perature confirm the equivalence5c of the three un-
coordinated pyrazolyl rings. In accordance, the IR spectrum
displays a shift of νCdN assigned to the pyridyl rings to higher
wavelengths compared to free (1) (i.e., 1601 or 1621 cm-1 for
(1) or (4), respectively, Supporting Information, Table S.1).

Article
Inorganic Chemistry, Vol. 49, No. 17, 2010 7949
Figure 4. ORTEP plot of [Ni(TpmPy)2]Cl2 (5), where the ellipsoids are shown at 50% of probability and the hydrogen atoms and the two chlorides are
omitted for clarity.
The tetrahedral coordination around the zinc is slightly
distorted with the internal angles of 100.69(8)° for
N1-Zn1-N2 and 119.77(3)° for Cl1-Zn1-Cl2, that is,
the larger angle concerns the chloride ligands. The Zn-N
characterized by IR, far-IR, NMR, MS, and elemental
analysis. Like its TpmPy analogue (4), complex (6)
bears the scorpionate ligands bound via the pyridyl
groups. Its 1H NMR spectrum shows, in fact, the
equivalence of its three pyrazolyl rings (without a
significant shift relative to the free ligand) and a lower
field coordination shift (of 0.14 and 0.33 ppm) for the
pyridyl protons. The 2, 6- and 4- pyridyl carbons
appear low field shifted in the 13C NMR spectrum, as
for the analogue (4). This feature appears to be common to
all the complexes that exhibit pyridyl-coordination, as
will be discussed below (see also Supporting Information,
Figure S.2). Compound (6) is very soluble in CHCl3,
CH2Cl2, acetone, and moderately soluble in MeOH, while is
insoluble in water.
˚
˚
bond lengths are identical (2.058(2) A and 2.053(2) A),
like the Zn-Cl distances, thus showing a symmetrical
elongation of the ideal tetrahedral geometry. The
O-Cmethylene-Cipso-Cortho torsion angles in (4) are
markedly disparate (135.26 and 177.97°, Table 2), in
contrast to the other complexes that present a different
coordination geometry (see below). π interactions are
also apparent (see Supporting Information, Figure S.5);
the distance between the N37-N39 pyrazolyl plane
˚
and the vicinal N2 pyridine plane is 4.054 A (centroid-
centroid) allowing a weak offset face-to-face stacking
fashion.
Reaction of 2 equiv of TpmPyPh (2) with NiCl2 in
methanol proceeds readily leading to the precipitation
of [NiCl2(TpmPyPh)2] (7) that also bears the scorpionate
ligands coordinated through the pyridyl moieties. Hence,
the pyrazolyl N6-coodination mode observed for (5), with
unsubstituted tris(pyrazolyl)methane ligands, is sterically
hindered for (7). The mass spectrum (EI) of (7) shows a
pattern of fragmentation that is equivalent to that of its
zinc analogue (6) (e.g., peaks at m/z 656 and 662 for
[Ni(TpmPyPh)Cl]þ and [Zn(TpmPyPh)Cl]þ, respectively).
The IR spectra of (6) and (7) show almost identical
profiles for the 1800-400 cm-1 region, in particular the
shifted band at 1617 cm-1 ascribed to νCdN of the
coordinated pyridyl moiety (see Supporting Information,
Figure S.7 and Table S.1). The 1H NMR spectrum of (7)
shows broad resonances where it is possible to distinguish
those assigned to the pyrazolyl rings, while those of the
pyridyl moiety collapse because of the proximity of the
metal center.
In contrast to the case of ZnII, NiII chloride reacts with 2
equiv of (1) to give (Scheme 4) the corresponding sandwich
complex [Ni(TpmPy)2]Cl2 (5) bearing two trihapto TpmPy
ligands coordinated via the pyrazolyl rings, as shown by
X-ray diffraction analysis (Figure 4, Tables 1 and 2). The
octahedral N6-coordination of nickel(II) is consistent with
the 1H NMR spectrum that shows its typical paramagnetic
nature (octahedral NiII, S = 1). Compound (5) is well
soluble in water (S25 °C ≈ 50 mg mL-1), MeOH, and EtOH,
3
and sparingly soluble in CHCl3, CH2Cl2, and acetonitrile.
Similar to compound (3), the X-ray diffraction analysis
of (5) confirms the scorpionate sandwich structure. The
˚
Ni-N distances are very close (2.038-2.068 A range),
and the degree of tilting of the pyrazolyl rings is very low
(i.e., Ni-N-N-C torsion angles are within the range of
165.90°-178.04°). The disparity of the O-Cmethylene
-
Cipso-Cortho torsion angles is only of 6.5° (Table 2). The
main intermolecular interactions detected in (5) involve
C-H π interactions (see Supporting Information, Fig-
The reaction of TpmPy (1) with VIII chloride (Scheme 4)
also proceeds readily with the precipitation, as a pale blue
powder, of [VOCl2(TpmPy)] (8) with the N3-pyrazolyl
coordination. The compound has been characterized by
MS, IR, far-IR, and EPR spectroscopies, and elemental
analysis. The IR spectrum confirms the conceivable
N3-pyrazolyl coordination mode of the scorpionate, typical
for this type of compounds,12 since νCdN appears at
3 3 3
ure S.6). Each pyrazolyl hydrogen atoms H14 and H34
from one molecule is aimed at the π-clouds of the N2
and N1 pyridine rings, respectively, of a vicinal one;
the H centroid distances for these interactions are of
˚
3 3 3
2.599 and 2.728 A with C-H centroid angles of 156.49
3 3 3
and 154.28°.
Similarly to the previous synthetic procedures, we
studied the reactions of ZnII and NiII chlorides with
TpmPyPh (2). The latter, being sterically hindered at the
pyrazolyl-side, is expected to coordinate preferably
through the pyridyl moiety. In fact, reaction of (2) with
ZnCl2 in methanol leads readily to the quantitative
precipitation of [ZnCl2(TpmPyPh)2] (6) which has been
(12) (a) Silva, T. F. S.; Luzyanin, K. V.; Guedes da Silva, M. F. C.;
Martins, L. M. D. R. S.; Pombeiro, A. J. L. Adv. Synth. Catal. 2010, 352,
171–187. (b) Silva, T. F. S.; Alegria, E. C. B. A.; Martins, L. M. D. R. S.;
Pombeiro, A. J. L. Adv. Synth. Catal. 2008, 350, 706–716. (c) Mishra, G. S.;
Silva, T. F. S.; Martins, L. M. D. R. S.; Pombeiro, A. J. L. Pure Appl. Chem. 2009,
81, 1217–1227.

7950 Inorganic Chemistry, Vol. 49, No. 17, 2010
Scheme 5. Synthesis of [PdCl2(TpmPy)2] (9)
Wanke et al.
wavenumbers that are consistent with the coordinated-
pyrazolyl rings (i.e., 1519-1517 cm-1, see also Sup-
porting Information, Table S.1), whereas for the pyridyl-
coordinated compounds νCdN usually shifts to higher wave-
numbers (i.e., in the range of 1617-1621 cm-1, see below
and Supporting Information, Table S.1). The EPR spectrum
shows the expected signal (i.e., with a eight-line pattern, g =
1.9989) for a vanadium(IV) (d1, I = 7/2, S = 1/2).12
2.3. Reaction with PdII: Synthesis and Characterization
of [PdCl2(TpmPy)2] (9) and [PdCl2(TpmPyPh)2] (10).
Palladium(II) complexes bearing heterocyclic N-donor li-
gands are well-known, and the coordination chemistry of
Pd-based complexes with pyrazoles, imidazoles and pyri-
dines ligands has been fully developed.13 PdII reacts10d-g,14
easily with bis(pyrazolyl)methane (Bpm) and tris(pyrazolyl)-
methane (Tpm) to give typical square planar N,N-
coordination compounds (involving two ligated pyrazolyl
rings, and leaving one free in the case of Tpm). Moreover,
the recognized affinity15 of this metal with the pyridyl
N-donor group encouraged us to investigate its coordination
chemistry toward these new “pyridyl-based” scorpionates.
Reaction of cis-[PdCl2(CH3CN)2] with 2 equiv of (1) in
dichloromethane gives the disubstituted product [PdCl2-
(TpmPy)2] (9) in quantitative yield (Scheme 5). The com-
pound is stable and soluble in organic solvents such as
CH2Cl2 and CHCl3, but in DMSO undergoes a partial
decomposition. In the 1H NMR spectrum the remarkable
shift to lower field (by ca. 0.15 ppm) of the pyridyl
resonances relatively to those of the free ligand confirms
Figure 5. Shift of 2,6-C (*) and 4-C (•) pyridyl carbons resonances in13
C
NMR (400 MHz) spectra (CDCl3) upon coordination of free (2) to PdII in
[PdCl2(TpmPyPh)2] (10).
the coordination through the pyridyl moiety, whereas the
pyrazolyl groups remain equivalent.
The phenyl substituted analogue, [PdCl2(TpmPyPh)2]
(10), was prepared similarly, upon reaction of cis-[PdCl2-
(CH3CN)2] with (2). In this case, the coordination
through the pyridyl moiety is expected to be even more favo-
rable than for the unsubstituted (9), since the pyrazolyl-
side is highly hindered by the phenyl substituents. Com-
pound (10) shows NMR coordination shifts comparable
to those of (9). For instance, similarly to (9), the 13C NMR
(400 MHz) spectrum of (10) shows the 2,6- and 4-pyridyl
carbons resonances (at δ 152.9 and 150.4, respectively)
shifted to lower field (by 3.1 and 3.7 ppm, correspondingly)
relatively to the free ligand. This behavior supports the
expected deshielding upon pyridyl coordination, con-
firming that the ortho and the para positions are more
influenced than the meta position (Figure 5).
(13) (a) Tsuji, S.; Swenson, D. C.; Jordan, R. F. Organometallics 1999, 18,
4758–4764. (b) Lee, C. K.; Ling, M. J.; Lin, I. J. B. Dalton Trans. 2003, 4731–
4737. (c) Qin, Z.; Jennings, M. C.; Puddephatt, R. J.; Muir, K. W. Inorg. Chem.
2002, 41, 5174–5186.
(14) (a) Sanchez-Mendez, A.; Silvestri, G. F.; de Jesus, E.; F. J. de la
Mata, F. J.; Flores, J. C.; Gomez, R.; Gomez-Sal, P. Eur. J. Inorg. Chem.
2004, 3287–3296. (b) Canty, A. J.; Minchin, N. J.; Engelhardt, L. M.; Skelton,
B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 1986, 645–650.
(15) (a) Feth, M. P.; Klein, A.; Bertagnolli, H. Eur. J. Inorg. Chem. 2003,
839–852. (b) Hu, Y.-Z.; Chamchoumis, C.; Grebowicz, J. S.; Thummel, R. P.
Inorg. Chem. 2002, 41, 2296–2300.

Article
Inorganic Chemistry, Vol. 49, No. 17, 2010 7951
Figure 6. ORTEP plot of trans-[PdCl2(TpmPy)2] (9), where the ellipsoids are shown at 50% of probability. Hydrogen atoms are omitted for clarity.
Symmetry code to generate equivalent atoms: 2 - x, 2 - y, -z.
Scheme 6. Synthetic Pathways for [PdCl2(μ-TpmPy)2Fe](BF4)2 (11)
Similarly, the IR spectra of (9) and (10) show a dis-
placement to higher wavenumbers of the νCdN frequency
compared to that of the corresponding free ligands (1)
the analogue (10) shows just a single strong band at
365 cm-1, corresponding to the trans isomer, which is
preferably formed because of the steric hindrance of
TpmPyPh. Attempted chromatographic separation of
the two isomers of (9) resulted in decomposition of the
compound.
and (2) (from 1601 to 1619 and from 1603 to 1621 cm-1
,
for the (1)/(9) and (2)/(10) pairs, respectively; see Sup-
porting Information, Table S.1 and Figure S.8(a)). The
mass spectra of (9) and (10) confirm the presence of two
scorpionate ligands, and the far-IR spectra reveals
the bands ascribed to Pd-Cl stretching (Supporting
Information, Figure S.8(b)).16 For (9), the νPd-Cl at
308 and 296 cm-1, typical for a cis-isomer, appear
shifted to higher wavenumbers in comparison to those
of the starting compound cis-[PdCl2(CH3CN)2] (255
and 242 cm-1) suggesting a higher π-electron acceptor
character for the coordinated pyridyl species than that
of the acetonitrile ligand. Moreover, another band is
detected at 361 cm-1, being ascribed to the trans isomer,
also present in the solid state. On the other hand,
Furthermore, the trans isomer of (9) was identified in
the X-ray diffraction analysis (from very poor quality
crystals) that displays an almost perfect square-planar
geometry around the Pd(II) ion, with the two scorpio-
nates in trans position (Figure 6) and the N(1)-Pd(1)-
Cl(1) angles of 89.6(3)° (Table 2).
3.0. Applications of TpmPy (1) and TpmPyPh (2) to the
Synthesis of Bimetallic Complexes, [PdCl2(μ-TpmPy)2Fe]-
(BF4)2 (11), [Fe(μ-TpmPy)2Cu(NO3)2](BF4)2 (12), and
[PdCl2(μ-TpmPyPh)2Fe2(H2O)6](BF4)4 (13). To investi-
gate the multidentate ability of the new scorpionates of
this work and the versatility of the new complexes pre-
pared, we explored the “second” coordination step (b
and b0, Scheme 1) of the latter compounds.
(16) (a) Drahos, B.; Rohlik, Z.; Kotek, J.; Cisarova, I.; Hermann, P.
Dalton Trans. 2009, 4942–4953. (b) Gillard, R. D.; Pilbrow, M. F. J. Chem. Soc.,
Dalton Trans. 1974, 2320–2325. (c) Adams, D. M.; Chatt, J.; Gerratt, J.;
Westland, A. D. J. Chem. Soc. 1964, 734–739. (d) Goggin, P. L.; Goodfellow,
R. J. J. Chem. Soc. A 1966, 1462–1466. (e) Goodfellow, R. J.; Evans, J. G.;
Goggin, P. L.; Duddell, D. A. J. Chem. Soc. A 1968, 1604–1609. (f) Mastin, S. H.
Inorg. Chem. 1974, 13, 1003–1005.
Reaction of equimolar amounts of [Fe(TpmPy)2](BF4)2
(3) and cis-[PdCl2(CH3CN)2] gives [PdCl2(μ-TpmPy)2Fe]-
(BF4)2 (11) (Scheme 6(b)), which alternatively can be
obtained upon an equimolar reaction of [PdCl2(TpmPy)2]
(9) with Fe(BF4)2 6H2O (Scheme 6(b0)).
3

7952 Inorganic Chemistry, Vol. 49, No. 17, 2010
Wanke et al.
Compound (11) has been characterized by IR and NMR
spectroscopies, MS, and elemental analysis. Besides, its
variable temperature 1H NMR spectra indicate a fluxional
behavior, in solution, suggesting a dynamic equilibrium
between different structures.
in the solid state. In the cases of NiII, ZnII, and PdII, the extra
N-donor pyridyl group shows a good affinity to the metal
centers: the new pyridyl-based complexes of Ni, Zn, and Pd
(i.e., compounds (4), (6), (7), (9), and (10), respectively)
provide relevant examples in this field.
Similarly, reaction of [Fe(TpmPy)2](BF4)2 (3) with
Cu(NO3)2 2.5H2O leads to the immediate precipitation
Moreover, by increasing the bulkiness of the pyrazolyl
groups by introducing a phenyl substituent (as in (2)), the
coordination through the pyridyl-side is forced: the two
nickel complexes (5) and (7) (i.e., bearing the ligating scorpio-
nates in the N3-pyrazolyl and N-pyridyl coordination modes,
respectively) provide a good comparison model of steric
inducement.
3
of a pale violet solid of [Fe(μ-TpmPy)2Cu(NO3)2](BF4)2
(12), where each pyridyl moiety is coordinated to CuII.
This compound is well soluble in MeOH and sparingly
soluble in CH3CN, while it decomposes in H2O after a few
hours. The 1H NMR spectrum confirms the presence of
paramagnetic CuII, where the pyridyl resonances appear
more affected by the metal electronic state. In the mass
spectrum (EI) of (12), the peak at m/z 713, assigned to the
double charged [{Fe(μ-TpmPy)2Cu2(TpmPy)(NO3)3}-
(BF4)]þ2 fragment, suggests the possible formation of
higher nuclearity species.
In general, the 1H and 13C NMR, IR, and far-IR spectro-
scopies allowed to confirm the coordination modes of the
new scorpionate ligands in their metal complexes. In parti-
cular, 13C NMR and IR spectra are of diagnostic value to
distinguish between pyrazolyl- and pyridyl-coordination
(Supporting Information, Figures S.1, S.2, S.7, S.8 and Table
S.1). Hence, a significant low field shift (ca. Δδ 2-3 ppm)
for the 2, 6- and 4-pyridyl carbons in the 13C NMR spectra
is indicative of pyridyl coordination which also affects
the pyridyl IR νCdN values that shift to higher wavenumbers
(i.e., falling within the range of 1617-1621 cm-1, Supporting
Information, Table S.1). The consistency of these behaviors
illustrates an easy pattern for the characterization of these
new complexes.
The multifunctional ligands are particularly adequate to
the easy synthesis of heterobimetallic units, such as those of
the current study. This represents a first application of this
class of multidentate ligands that are expected to be able
to coordinate to a wide variety of metal centers and to
generate polymetallic species for further studies, for example,
in supramolecular and solid-supported chemistries, besides
the various fields of common applications of scorpionate
compounds.
In contrast with the synthesis of the full sandwich com-
pound (11), the reaction of [PdCl2(TpmPyPh)] (10) with
Fe(BF4)2 6H2O gives the hydrated half sandwich complex
3
[PdCl2(μ-TpmPyPh)2Fe2(H2O)6](BF4)4 (13) bearing each
iron coordinated by the three pyrazolyl rings of just one
bridging TpmPyPh. Steric hindrance of the bulky TpmPyPh
prevents the formation of the N6-sandwich coordination at
FeII (which occurs for compound (11)) leaving three coordi-
nation positions available for small ligands, such as water.8a
The 1H NMR spectrum of (13) is consistent with that of its
precursor (10), and shows a modest shift of the pyrazolyl
resonances on account of coordination to iron(II).
The possibility of those compounds to arrange in poly-
meric structures could not be ruled out and eventually
thwarted the crystallization attempts and prevented their
complete characterization.
Conclusion
Acknowledgment. This work has been partially sup-
ported by the Foundation for Science and Technology
(FCT) and the Grants SFRH/BD/23187/2005 (R.W.)
and SFRH/BD/48087/2008 (T.F.S.S).
We prepared a new multifunctional class of scorpionates
bearing a pyridyl group pending from the methine carbon,
TpmPy and TpmPyPh, and studied their coordination chem-
istry with different metal centers. In the case of FeII, NMR
and X-ray analyses of compound (3) reveal, by comparison
with the Tpm analogous complex, that the pyridyl moiety
promotes the stabilization of the LS state of FeII up to 400 K
Supporting Information Available: Further details are given in
Figures S.1-S.8 and Table S.1. This material is available free of
charge via the Internet at http://pubs.acs.org.