Heteropolymetallic compounds containing 1,1′-bis(diphenylphosphino)ferrocene (DPPF) and pyrazolate ligands: Synthesis, spectroscopic characterization and reactivity. Crystal and molecular structure of [(DPPF)Pt(az)2] [azH = pyrazole (pzH) or 3,5-dimethylpyrazole] and [(DPPF)Pt(μ-pz)2CdI2]

Article abstract of DOI:10.1039/a805432k

From the interaction between [(DPPF)Pt(az)₂] [DPPF = 1,1′-bis(diphenylphosphino)ferrocene; azH = pyrazole (pzH), 3,5-dimethylpyrazole (3,5-Me₂pzH) or 4-methylpyrazole (4-MepzH)] and several MX₂ acceptors (M = Zn, X = Cl, Br, I or BF₄; M = Cd, X = Cl, Br, I or ClO₄, M = Hg, X = Cl, Br or I; M = Ba, X = I) 16 novel heteropolymetallic compounds were synthesized and characterized by IR, far-IR, ¹H and ³¹P, and in some cases also with ¹¹³Cd, NMR spectroscopy. Heterotrinuclear adducts [(DPPF)Pt(μ-az)₂MX₂] were obtained when X = halide, whereas ionic heteropentanuclear complexes [{(DPPF)Pt(μ₂-az)₂}₂M]²⁺[X] ₂^2- were afforded when X is a weak nucleophile (ClO₄ or BF₄). Scrambling of the ligands occurred when the reaction between [(DPPF)Pt(az)₂] and Cu(II)X₂ salts (X = Cl or Br) was carried out in methanol, [(DPPF)PtX₂] being always obtained. X-Ray crystallography confirms the mononuclear structure of [(DPPF)Pt(az)₂] (azH = pyrazole or 3,5-methylpyrazole), in which the Pt atom is in a distorted cis square planar coordination with the two cyclopentadienyl rings in a staggered conformation. In the heterotrinuclear [(DPPF)Pt(μ-pz)₂CdI₂], the cadmium atom is strongly distorted tetrahedral, coordinated by two N-atoms of pyrazolate rings and two iodine atoms. Copyright 1998 by the Royal Society of Chemistry.

Full text of DOI:10.1039/a805432k

View Article Online / Journal Homepage / Table of Contents for this issue
Heteropolymetallic compounds containing 1,1Ј-bis(diphenyl-
phosphino)ferrocene (DPPF) and pyrazolate ligands: synthesis,
spectroscopic characterization and reactivity. Crystal and
molecular structure of [(DPPF)Pt(az)2] [azH ؍ pyrazole (pzH)
or 3,5-dimethylpyrazole] and [(DPPF)Pt(ì-pz)2CdI2]
Claudio Pettinari,a Fabio Marchetti,a Augusto Cingolani,a Sergei I. Troyanovb and
Andrei Drozdovb
a Dipartimento di Scienze Chimiche, Università degli Studi, via S. Agostino 1, 62032 Camerino,
Italy. E-mail: Pettinar@canserv.unicam.it
b Moscow State University, Chemistry Department, Vorobjevy Gory, 119899 Moscow, Russia.
E-mail: drozdov@inorg.chem.msu.ru
Received 13th July 1998, Accepted 11th August 1998
From the interaction between [(DPPF)Pt(az)2] [DPPF = 1,1Ј-bis(diphenylphosphino)ferrocene; azH = pyrazole
(pzH), 3,5-dimethylpyrazole (3,5-Me2pzH) or 4-methylpyrazole (4-MepzH)] and several MX2 acceptors (M = Zn,
X = Cl, Br, I or BF4; M = Cd, X = Cl, Br, I or ClO4, M = Hg, X = Cl, Br or I; M = Ba, X = I) 16 novel heteropoly-
metallic compounds were synthesized and characterized by IR, far-IR, 1H and 31P, and in some cases also with 113Cd,
NMR spectroscopy. Heterotrinuclear adducts [(DPPF)Pt(µ-az)2MX2] were obtained when X = halide, whereas ionic
heteropentanuclear complexes [{(DPPF)Pt(µ2-az)2}2M]2ϩ[X]22Ϫ were afforded when X is a weak nucleophile (ClO4
or BF4). Scrambling of the ligands occurred when the reaction between [(DPPF)Pt(az)2] and Cu()X2 salts (X = Cl
or Br) was carried out in methanol, [(DPPF)PtX2] being always obtained. X-Ray crystallography confirms the
mononuclear structure of [(DPPF)Pt(az)2] (azH = pyrazole or 3,5-methylpyrazole), in which the Pt atom is in a
distorted cis square planar coordination with the two cyclopentadienyl rings in a staggered conformation. In the
heterotrinuclear [(DPPF)Pt(µ-pz)2CdI2], the cadmium atom is strongly distorted tetrahedral, coordinated by two
N-atoms of pyrazolate rings and two iodine atoms.
Pyrazole-type heterocycles represent an important class of
ligands and their coordination chemistry has been the subject
of an excellent review.1 It has been shown that they can act as
neutral or anionic monodentate, or also as exobidentate anionic
ligands towards several metal and organometallic centers. In
the exobidentate form they can be used also to synthesize new
heteropolymetallic compounds.2,3 During the last years the
interest in this field increased due to a number of potential
properties of these compounds such as catalytic activity4 and
bioactivity5 dependent on the cooperative effects of different
metal centers.
Several heteropolymetallic systems involving platinum()
and palladium() of general formula [(L–L)M(µ-az)2MЈX2]
and [{(L–L)M(µ-az)2}2MЈ]X2 (where L–L is a chelating ligand,
M = Pt or Pd, azH = various pyrazoles, MЈ = Zn, Cd, Co or Ni
and X = halide, nitrate, tetrafluoroborate or perchlorate) have
been described and spectroscopically characterized.6–9 In some
of these complexes both of the pyrazolates are coordinated to
the palladium or platinum center through one of the nitrogen
atoms, whereas the other nitrogen atom is coordinated to a Zn,
Cd, Co or Ni center, so that the [(L–L)M(az)2] moiety can be
considered as a potentially bidentate ligand.
In recent years we have synthesized new platinum complexes
with 1,2-bis(diphenylphosphino)ethane and investigated some
aspects of their reactivity.11 On account of the interest in the
chemistry of Pt() derivatives with bis(diphenylphosphino)-
ferrocene ligands (DPPF), we have extended our investigation
to the synthesis of heteropolymetallic complexes containing
the (DPPF)Pt() moiety. Here we report the synthesis and
spectroscopic characterization of new (DPPF)Pt(µ-az)2 [azH =
pyrazole (pzH), 3,5-dimethylpyrazole (3,5-Me2pzH) or
4-methylpyrazole (4-MepzH)] derivatives and their complexes
with zinc(), cadmium(), mercury(), barium() and also the
results on their interaction with copper() acceptors. The
X-ray crystal structure determination of two (DPPF)-
Pt(µ-az)2 (az = pz or 3,5-Me2pz) donors and of the pz complex
with cadmium(II) iodide (which is so far the first complex of
this kind to be structurally characterized) have been also
reported.
Experimental
Reagents and apparatus
More recently the synthesis and characterization of several
hydride and carbonyl platinum() complexes containing the
1,1Ј-bis(diphenylphosphino)ferrocene ligand has been reported
and it has been shown that the Pt coordination environment
can undergo a significant distortion from square planar
coordination.10 These compounds are very interesting also
from a purely structural viewpoint. For example, the catalytic
properties of these systems are often related to the possible
conformation of the cyclopentadienyl rings.
All reagents and solvents were obtained from commercial
sources and were used without further purification unless
otherwise stated.
The samples for microanalysis were dried under vacuum to
constant weight (20 ЊC, ca. 0.1 Torr). Elemental analyses
(C,H,N) were performed in house with a Fisons Instruments
1108 CHNS-O Elemental analyser. IR spectra were recorded
from 4000 to 100 cmϪ1 with a Perkin-Elmer System 2000 FT-IR
instrument. 1H, 13C, 31P and 113Cd NMR spectra were recorded
J. Chem. Soc., Dalton Trans., 1998, 3335–3342
3335

View Article Online
on a VXR-300 Varian spectrometer operating at room temper-
ature (300 MHz for 1H, 75 MHz for 13C, 66.55 MHz for
113Cd, 121.4 MHz for 31P; SiMe4 used as internal standard).
Melting points were determined on an IA 8100 Electrothermal
instrument. The electrical conductance of the solutions was
measured with a Crison CDTM 522 conductimeter at room
temperature.
mp 128–130 ЊC (decomp.) (Found: C, 55.96; H, 4.10; N, 6.05.
Calc. for C42H38FeN4P2Pt: C, 55.35; H, 4.17; N, 6.15%). IR
(Nujol mull, cmϪ1): 3053w [ν(C–H)], 1520m, 1570w (breathing
pz), 525m, 518s, 501w, 462m, 448m, 425s [Cp–PPh2], 495vs,
1
485m (Cp tilt), 475vs [ν(Fe–Cp)]. H NMR (CDCl3): δ 1.67 (s,
6 H, 4-CH3), 4.33 (d, 8 H, HCp), 6.49 (d br, 2 H, 5-CH), 6.72 (br,
2 H, 3-CH), 7.20 (t), 7.38 (t), 7.74 (m) (20 H, C6H5). 31P NMR
(CDCl3): δ ϩ7.35 [t, 1J(Pt–P) = 3184 Hz].
Synthesis of the donors
Synthesis of the metal adducts
[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II) L1. A chloroform solution (50 ml) of 1,1Ј-
bis(diphenylphosphino)ferrocene (5.544 g, 10 mmol) was added
to a chloroform solution (50 ml) of (COD)PtCl2 (3.742 g, 10
mmol), the mixture was stirred at room temperature for 1 h.
After the addition of diethyl ether (100 ml) a pale yellow pre-
cipitate formed, which was filtered off, washed with diethyl
ether (30 ml), recrystallized twice from dichloromethane–
diethyl ether and shown to be (DPPF)PtCl2 [yield 85%,
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II)}zinc(II) chloride [(L1)ZnCl2] 1. Zinc() chloride
(0.136 g, 1 mmol) was added to a methanol solution (30 ml) of
L1 (0.884 g, 1 mmol). A yellow precipitate immediately formed.
The mixture was stirred at room temperature for 4 h, then
it was filtered to separate the precipitate, which was washed
with diethyl ether (20 ml) and dried under reduced pressure.
Recrystallization was performed with chloroform–diethyl ether.
Yield 90%, mp 300–302 ЊC (Found: C, 46.90; H, 3.42; N, 5.12.
Calc. for C40H34Cl2FeN4P2PtZn: C, 47.11; H, 3.36; N, 5.49%).
IR (Nujol mull, cmϪ1): 3060w [ν(C–H)], 1575w (breathing pz),
516s, 444m, 435m [Cp–PPh2], 495vs (Cp tilt), 474vs [ν(Fe–Cp)],
304s, 280m [ν(Zn–Cl)]. 1H NMR (CDCl3): δ 3.81 (d, 2 H, HCp),
4.17 (d, 2 H, HCp), 4.41 (d, 4 H, HCp), 5.11 (d, 4 H, HCp), 5.48 (s,
31P-{1H} NMR(CDCl3): δ ϩ13.5 (t, J(Pt–P) = 3766.6 Hz)]. A
1
methanol solution (100 ml) of KOH (1.680 g, 30 mmol) and
pyrazole (2.043 g, 30 mmol) was added to a suspension of
(DPPF)PtCl2 (8.204 g, 10 mmol) in the same solvent (60 ml).
The mixture was stirred under heating at ca. 50 ЊC for 1 d and
then was evaporated to dryness on the rotary evaporator. The
crude product was treated with dichloromethane (50 ml) and
then filtered off to completely remove the excess of potassium
pyrazolate and KCl formed. By slow addition of diethyl ether
(50 ml) an orange-yellow precipitate was obtained, which was
filtered off, washed with ethanol–diethyl ether (1:1, 30 ml),
dried under reduced pressure, recrystallized twice in dichloro-
methane–diethyl ether and shown to be derivative L1. Yield
62%, mp 230 ЊC (decomp.) (Found: C, 54.60; H, 3.78; N,
6.30. Calc. for C40H34FeN4P2Pt: C, 54.37; H, 3.88; N, 6.34%).
IR (Nujol mull, cmϪ1): 3050w [ν(C–H)], 1570w, 1586w
(breathing pz), 532m, 518s, 506w, 433m [Cp–PPh2], 495vs,
2
2 H, 4-CH), 6.94 [d, 2 H, 5-CH, J(H–H) = 1.8 Hz], 7.35 (br,
2 H, 3-CH), 7.18 (m br), 7.55 (m br), 7.80 (m br), 8.24 (d), 8.27
(d) (20 H, C6H5). 31P NMR (CDCl3): δ ϩ7.72 [t, J(Pt–P) =
1
3333.1 Hz].
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II)}zinc(II) bromide [(L1)ZnBr2] 2. The compound was
prepared and crystallized as for 1 using zinc() bromide (0.255
g, 1 mmol). Yield 78%, mp 328–330 ЊC (Found: C, 43.30; H,
3.04; N, 5.03. Calc. for C40H34Br2FeN4P2PtZn: C, 43.33; H,
3.09; N, 5.05%). IR (Nujol mull, cmϪ1): 3055w [ν(C–H)], 1568w
(breathing pz), 520m, 512s, 441s [Cp–PPh2], 498vs (Cp tilt),
477s [ν(Fe–Cp)], 237s, 215m [ν(Zn–Br)]. 1H NMR (CDCl3):
δ 3.87 (d, 2 H, HCp), 4.20 (d, 2 H, HCp), 4.46 (d, 2 H, HCp),
5.20 (d, 2 H, HCp), 5.53 (pt, 2 H, 4-CH), 6.95 [pd, 2 H, 5-CH,
2J(H–H) = 2.1 Hz], 7.42 (br, 2 H, 3-CH), 7.17 (m br), 7.36
(m br), 7.58 (m br), 7.88 (m br), 8.24 (d), 8.27 (d) (20 H, C6H5).
31P NMR (CDCl3): δ ϩ7.74 [t, 1J(Pt–P) = 3331.4 Hz].
1
485m (Cp tilt), 473vs [ν(Fe–Cp)]. H NMR (CDCl3): δ 4.29
(d, 4 H, HCp), 4.33 (d, 4 H, HCp), 5.66 (pt, 2 H, 4-CH), 6.70
[pseudo-doublet pd, 2 H, 5-CH, J(Pt–H) = 1.0 Hz], 6.98 (pd,
3
2 H, 3-CH), 7.24 (t), 7.34 (t), 7.68 (d), 7.72 (d) (20 H, C6H5).
13C NMR (CDCl3): δ 73.9 (pseudo-triplet pt, Cp), 76.2 [pt, Cp,
3J(Pt–C) = 15.1], 77.4 (s, Cp), 103.6 [t br, C4, 3J(Pt–C) = 27.1],
2
3
136.0 [t br, C5, J(Pt–C) = 54.5], 139.8 [t br, C3, J(Pt–C) =
3
55.3], 128.3 [m, C6H5, J(P–C) = 11.0], 131.0 (m, C6H5), 132.1
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II)}cadmium(II) chloride [(L1)CdCl2] 3. The compound
was prepared and crystallized as for 1 using cadmium() chlor-
ide (0.183 g, 1 mmol). Yield 76%, mp 239–243 ЊC (Found: C,
44.83; H, 3.06; N, 5.05. Calc. for C40H34CdCl2FeN4P2Pt: C,
45.03; H, 3.21; N, 5.25%). IR (Nujol mull, cmϪ1): 3072w
[ν(C–H)], 1578w (breathing pz), 520vs, 454m, 440s [Cp–PPh2],
497vs, 485s (Cp tilt), 473vs [ν(Fe–Cp)], 287s, 225s [ν(Cd–Cl)].
1H NMR (CDCl3): δ 3.95 (d, 2 H, HCp), 4.23 (d, 2 H, HCp), 4.51
(d, 2 H, HCp), 5.23 (d, 2 H, HCp), 5.65 (br, 2 H, 4-CH), 6.98 [d,
(m, C6H5), 134.8 [m, C6H5, 2J(P–C) = 11.2 Hz]. 31P NMR
(CDCl3): δ ϩ7.87 [t, 1J(Pt–P) = 3194.6 Hz].
[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II) L2. Derivative L2 has been obtained
similarly to L1, by using 3,5-dimethylpyrazole. The crude
product obtained was recrystallized twice from methanol–
diethyl ether. Yield 55%, mp 230 ЊC (decomp.) (Found: C,
55.12; H, 4.66; N, 5.86. Calc. for C44H42FeN4P2Pt: C, 55.09;
H, 4.62; N, 6.12%). IR (Nujol mull, cmϪ1): 3048w [ν(C–H)],
1522m, 1570w (breathing pz), 533m, 519s, 506w, 462m, 453m,
445m, 433s [Cp–PPh2], 496vs, 485m (Cp tilt), 473vs [ν(Fe–Cp)].
1H NMR (CDCl3): δ 1.70 (s, 6 H, 3- or 5-CH3), 1.74 (s, 6 H,
3- or 5-CH3), 4.32 (d, 4 H, HCp), 4.39 (d, 4 H, HCp), 5.09 (br, 2
2
2 H, 5-CH, J(H–H) = 2.0 Hz], 7.21 (br, 2 H, 3-CH), 7.26 (t),
7.60 (m), 8.23 (d), 8.26 (d) (20 H, C6H5). 31P NMR (CDCl3):
δ ϩ7.44 [t, 1J(Pt–P) = 3290.5 Hz]. 113Cd NMR (CDCl3): δ 437.
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II)}cadmium(II) bromide [(L1)CdBr2] 4. The compound
was prepared and crystallized as for 1 using cadmium() brom-
ide tetrahydrate (0.334 g, 1 mmol). Yield 83%, mp 305–308 ЊC
(Found: C, 41.20; H, 2.99; N, 4.73. Calc. for C40H34Br2-
CdFeN4P2Pt: C, 41.57; H, 2.97; N, 4.85%). IR (Nujol mull,
cmϪ1): 3080w [ν(C–H)], 1572w, 1587w (breathing pz), 520m,
512m, 457w, 442s [Cp–PPh2], 497vs (Cp tilt), 474s [ν(Fe–Cp)],
204s, 187m [ν(Cd–Br)]. 1H NMR (CDCl3): δ 3.97 (d, 2 H, HCp),
4.24 (d, 2 H, HCp), 4.50 (d, 2 H, HCp), 5.17 (d, 2 H, HCp), 5.64
(br, 2 H, 4-CH), 6.98 (br, 2 H, 5-CH), 7.21 (br, 2 H, 3-CH), 7.26
(m), 7.63 (m), 8.21 (d), 8.26 (d) (20 H, C6H5). 31P NMR
(CDCl3): δ ϩ7.36 [t, 1J(Pt–P) = 3285.0 Hz].
H, 4-CH), 7.24 (t), 7.35 (t), 7.64 (d), 7.68 (d) (20 H, C6H5). 13
NMR (CDCl3): δ 13.6 (s br, 3- or 5-CH3), 14.2 (s br, 3- or
C
3
5-CH3), 73.7 [pseudo-quartet pq, Cp, J(P–C) = 7.0], 76.2 [d,
Cp, 2J(P–C) = 9.6], 77.7 (s, Cp), 103.5 [t br, C4, 2J(P–C) = 16.7],
127.8 [m, C6H5, 3J(PC) = 11.2], 130.7 (m, C6H5), 132.2 (m,
C6H5), 135.1 [m, C6H5, 3J(P–C) = 11.2 Hz], 145.5 (s, C5), 147.4
(s, C3). 31P NMR (CDCl3): δ ϩ5.74 [t, 1J(Pt–P) = 3164.7 Hz].
[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(4-methylpyrazol-1-
yl)platinum(II) L3. Derivative L3 has been obtained similarly to
L1, by using 4-methylpyrazole. The crude product obtained was
recrystallized twice from methanol–diethyl ether. Yield 70%,
3336
J. Chem. Soc., Dalton Trans., 1998, 3335–3342

View Article Online
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II)}cadmium(II) iodide [(L1)CdI2] 5. The compound
was prepared and crystallized as for 1 using cadmium iodide
(0.366 g, 1 mmol). Yield 84%, mp 309–312 ЊC (Found: C, 38.12;
H, 2.65; N, 4.26. Calc. for C40H34CdFeI2N4P2Pt: C, 38.44; H,
2.74; N, 4.48%). IR (Nujol mull, cmϪ1): 3075w [ν(C–H)], 1583w
(breathing pz), 518m, 455m, 444m, 434w [Cp–PPh2], 493vs (Cp
tilt), 477vs [ν(Fe–Cp)]. 1H NMR (CDCl3): δ 3.94 (d, 2 H, HCp),
4.23 (d, 2 H, HCp), 4.47 (d, 2 H, HCp), 5.12 (d, 2 H, HCp), 5.62 (s,
(s, 6 H, 3- or 5-CH3), 4.21 (d, 2 H, HCp), 4.29 (d, 2 H, HCp), 4.41
(d, 2 H, HCp), 4.85 (d, 2 H, HCp), 5.24 (s, 2 H, 4-CH), 7.35 (m),
7.56 (m), 7.90 (m) (20 H, C6H5). 31P NMR (CDCl3): δ ϩ2.03
[t, 1J(Pt–P) = 3212.9 Hz].
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}mercury(II) chloride [(L2)HgCl2] 10.
The compound was prepared and crystallized as for 8 using
mercury() chloride (0.271 g, 1 mmol). Yield 81%, mp 260–
262 ЊC (Found: C, 43.25; H, 3.60; N, 4.52. Calc. for C44H42-
Cl2FeHgN4P2Pt: C, 43.63; H, 3.50; N, 4.63%). IR (Nujol mull,
cmϪ1): 3085w [ν(C–H)], 1523m, 1565w (breathing pz), 517s,
504m, 444m [Cp–PPh2], 493vs (Cp tilt), 469s [ν(Fe–Cp)], 311m
[ν(Hg–Cl)]. 1H NMR (CDCl3): δ 1.75 (s, 6 H, 3- or 5-CH3), 2.12
(s, 6 H, 3- or 5-CH3), 4.19 (d, 2 H, HCp), 4.22 (d, 2 H, HCp), 4.28
(d, 2 H, HCp), 4.37 (d, 2 H, HCp), 5.36 (s, 2 H, 4-CH), 7.20 (m),
7.35 (m), 7.58 (m), 7.87 (m) (20 H, C6H5). 31P NMR (CDCl3):
δ ϩ1.53 [t, 1J(Pt–P) = 3242.2 Hz].
2
2 H, 4-CH), 6.95 [d, 2 H, 5-CH, J(H–H) = 1.5 Hz], 7.32 (br,
2 H, 3-CH), 7.20 (m), 7.56 (m), 8.19 (d), 8.20 (d) (20 H, C6H5).
1
31P NMR (CDCl3): δ ϩ7.19 [t, J(Pt–P) = 3280.8 Hz]. 113Cd
NMR (CDCl3): δ 349.
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II)}mercury(II) bromide [(L1)HgBr2] 6. The compound
was prepared and crystallized as for 1 using mercury()
bromide (0.360 g, 1 mmol). Yield 88%, mp 218 ЊC (decomp.)
(Found: C, 38.24; H, 2.91; N, 4.32. Calc. for C40H34Br2FeHg-
N4P2Pt: C, 38.62; H, 2.75; N, 4.50%). IR (Nujol mull, cmϪ1):
3065w [ν(C–H)], 1570w (breathing pz), 517s, 444m, 436m
[Cp–PPh2], 494vs (Cp tilt), 470vs [ν(Fe–Cp)], 178s, 171s
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}mercury(II) bromide [(L2)HgBr2] 11.
The compound was prepared and crystallized as for 8 using
mercury() bromide (0.360 g, 1 mmol). Yield 85%, mp 240–
245 ЊC (Found: C, 40.14; H, 3.12; N, 4.02. Calc. for C44H42-
Br2FeHgN4P2Pt: C, 40.65; H, 3.26; N, 4.31%). IR (Nujol mull,
cmϪ1): 3078w [ν(C–H)], 1524m, 1572w, 1586w (breathing
pz), 519s, 506s, 442s [Cp–PPh2], 495vs, 488s (Cp tilt), 470s
[ν(Fe–Cp)], 179vs, 164s [ν(Hg–Br)]. 1H NMR (CDCl3):
δ 1.65 (s, 6 H, 3- or 5-CH3), 2.05 (s, 6 H, 3- or 5-CH3), 4.27
(d, 2 H, HCp), 4.30 (d, 2 H, HCp), 4.39 (d, 2 H, HCp), 4.82 (d, 2 H,
HCp), 5.32 (s, 2 H, 4-CH), 7.41 (m), 7.59 (m), 7.88 (m) (20 H,
C6H5). 31P NMR (CDCl3): δ ϩ2.22 [t, 1J(Pt–P) = 3221.5 Hz].
1
[ν(Hg–Br)]. H NMR (CDCl3): δ 4.08 (br, 2 H, HCp), 4.32 (br,
2 H, HCp), 4.45 (br, 2 H, HCp), 5.03 (br, 2 H, HCp), 5.63 (br, 2 H,
4-CH), 6.88 (br, 2 H, 5-CH), 7.29 (s, 2 H, 3-CH), 7.20 (m br),
7.42 (m br), 7.62 (m br), 8.04 (m br), 8.22 (m br) (20 H, C6H5).
31P NMR (CDCl3): δ ϩ6.95 [t, 1J(Pt–P) = 3283.7 Hz].
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(pyrazol-1-yl)-
platinum(II)}mercury(II) iodide [(L1)HgI2] 7. The compound was
prepared and crystallized as for 1 using mercury() iodide
(0.454 g, 1 mmol). Yield 88%, mp 266–268 ЊC (Found: C, 35.66;
H, 2.68; N, 4.23. Calc. for C40H34FeHgI2N4P2Pt: C, 35.91; H,
2.56; N, 4.19%). IR (Nujol mull, cmϪ1): 3070w [ν(C–H)], 1573w
(breathing pz), 518s, 456m, 444m, 434m [Cp–PPh2], 493vs (Cp
tilt), 476vs [ν(Fe–Cp)]. 1H NMR (CDCl3): δ 4.12 (br, 2 H, HCp),
4.28 (br, 2 H, HCp), 4.42 (br, 2 H, HCp), 4.98 (br, 2 H, HCp), 5.62
(pt, 2 H, 4-CH), 6.80 [pd, 2 H, 5-CH, 2J(H–H) = 1.8 Hz], 7.29
(s, 2 H, 3-CH), 7.25 (m br), 7.53 (m br), 7.62 (m br), 8.06 (m br)
(20 H, C6H5). 31P NMR (CDCl3): δ ϩ6.69 [t, 1J(Pt–P) = 3271.7
Hz].
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}mercury(II) iodide [(L2)HgI2] 12. The
compound was prepared and crystallized as for 8 using
mercury() iodide (0.454 g, 1 mmol). Yield 90%, mp 245–
248 ЊC (Found: C, 37.68; H, 3.05; N, 3.94. Calc. for C44H42-
FeHgI2N4P2Pt: C, 37.91; H, 3.04; N, 4.02%). IR (Nujol mull,
cmϪ1): 3066w [ν(C–H)], 1523m, 1572w, 1586w (breathing pz),
526m, 507m, 447s, 441s [Cp–PPh2], 450vs, 488m (Cp tilt),
471s [ν(Fe–Cp)], 142s, 128m [ν(Hg–I)]. 1H NMR (CDCl3):
δ 1.67 (s, 6 H, 3- or 5-CH3), 2.06 (s, 6 H, 3- or 5-CH3), 4.32 (d,
2 H, HCp), 4.37 (d, 2 H, HCp), 4.48 (d, 2 H, HCp), 4.74 (d, 2 H,
HCp), 5.27 (s, 2 H, 4-CH), 7.52 (m), 7.58 (m), 7.68 (m), 7.98 (m)
(20 H, C6H5). 31P NMR (CDCl3): δ ϩ1.97 [t, 1J(Pt–P) = 3209.9
Hz].
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}cadmium(II) bromide [(L2)CdBr2] 8.
Cadmium() bromide tetrahydrate (0.344 g, 1 mmol) was added
to a methanol solution (30 ml) of L2 (0.940 g, 1 mmol). A
yellow precipitate immediately formed. The mixture was stirred
at room temperature for 4 h and then the precipitate was separ-
ated by filtration, washed with diethyl ether (20 ml) and taken
to dryness under reduced pressure. Recrystallization was per-
formed with chloroform–diethyl ether. Yield 84%, mp 255–
257 ЊC (Found: C, 43.44; H, 3.42; N, 4.50. Calc. for C44H42-
Br2CdFeN4P2Pt: C, 43.61; H, 3.49; N, 4.62%). IR (Nujol mull,
cmϪ1): 3065w [ν(C–H)], 1525m, 1573w, 1586w (breathing pz),
518s, 506s, 452m, 444s [Cp–PPh2], 495vs, 488s (Cp tilt), 470s
[ν(Fe–Cp)], 194s, 182s [ν(Cd–Br)]. 1H NMR (CDCl3): δ 1.67 (s,
6 H, 3- or 5-CH3), 2.07 (s, 6 H, 3- or 5-CH3), 4.20 (d, 2 H, HCp),
4.26 (d, 2 H, HCp), 4.38 (d, 2 H, HCp), 4.92 (d, 2 H, HCp), 5.27 (s,
2 H, 4-CH), 7.39m, 7.62m, 7.90m (20 H, C6H5). 31P NMR
(CDCl3): δ ϩ2.10 [t, 1J(Pt–P) = 3212.4 Hz].
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(4-methylpyrazol-
1-yl)platinum(II)}cadmium(II) iodide [(L3)CdI2] 13. Cadmium()
iodide (0.366 g, 1 mmol) was added to a methanol solution
(30 ml) of L3 (0.911 g, 1 mmol). A yellow precipitate immedi-
ately formed. The mixture was stirred at room temperature for
4 h then it was filtered to separate the precipitate, which was
washed with diethyl ether (20 ml) and dried under reduced pres-
sure. Recrystallization was performed with chloroform–diethyl
ether. Yield 90%, mp 299–303 ЊC (decomp.) (Found: C, 35.43;
H, 3.25; N, 4.25. Calc. for C42H38CdFeI2N4P2Pt: C, 35.73; H,
3.13; N, 4.39%). IR (Nujol mull, cmϪ1): 3055w [ν(C–H)],
1522m, 1575w (breathing pz), 520m, 519s, 497w, 462m, 454m,
1
420s [Cp–PPh2], 455vs, 485m (Cp tilt), 475vs [ν(Fe–Cp)]. H
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}cadmium(II) iodide [(L2)CdI2] 9. The
compound was prepared and crystallized as for 8 using cad-
mium() iodide (0.366 g, 1 mmol). Yield 84%, mp 225 ЊC
(decomp.) (Found: C, 40.20; H, 3.19; N, 4.12. Calc. for C44H42-
CdFeI2N4P2Pt: C, 40.47; H, 3.24; N, 4.29%). IR (Nujol mull,
cmϪ1): 3072w [ν(C–H)], 1520m, 1570w (breathing pz), 524m,
506m, 454m, 441s [Cp–PPh2], 499vs, 487s (Cp tilt), 471vs
[ν(Fe–Cp)]. 1H NMR (CDCl3): δ 1.72 (s, 6 H, 3- or 5-CH3), 2.10
NMR (CDCl3): δ 1.53 (s, 6 H, 4-CH3), 3.96 (d, 2 H, HCp), 4.26
(d, 2 H, HCp), 4.50 (d, 2 H, HCp), 5.15 (d, 2 H, HCp), 6.66 (d br,
2 H, 5-CH), 7.06 (br, 2 H, 3-CH), 7.16 (t), 7.67 (t), 8.10 (d),
8.16 (d) (20 H, C6H5). 31P NMR (CDCl3): δ ϩ7.1 [t, 1J(Pt–P) =
3264.9 Hz].
{[1,1Ј-Bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}barium(II) iodide [(L2)BaI2] 14. Bar-
ium() iodide (0.391 g, 1 mmol) was added to a solution of L2
J. Chem. Soc., Dalton Trans., 1998, 3335–3342
3337

View Article Online
Table 1 Crystal data and structure refinement for L1, L2 and 5ؒ0.45CH2Cl2
L1
L2
5ؒ0.45CH2Cl2
Empirical formula
Formula weight
C40H34FeN4P2Pt
883.59
C44H42FeN4P2Pt
939.74
C40.45H34.9CdCl0.9FeI2N4P2Pt
1288.07
T/K
λ/Å
293(2)
0.71069
293(2)
0.71073
293(2)
0.71073
Crystal system
Space group
Triclinic
P1
Triclinic
P1
Monoclinic
C2/c
¯
¯
a/Å
b/Å
12.163(2)
17.721(4)
12.085(2)
15.935(3)
35.376(10)
13.522(7)
c/Å
α/Њ
19.079(4)
92.48(3)
21.785(4)
79.82(3)
19.749(8)
β/Њ
97.35(3)
95.52(3)
4053.2(14)
4
1.448
77.34(3)
88.58(3)
4028.4(13)
4
1.553
116.22(3)
γ/Њ
U/Å3
8475(6)
8
2.019
5.751
Z
Dc/Mg mϪ3
µ/mmϪ1
3.915
3.944
Crystal size/mm
θ Range for data collection/Њ
Index ranges
0.5 × 0.2 × 0.2
1.54–22.01
Ϫ12 р h р 12, Ϫ18 р k р 18,
0 р l р 20
9937
0.5 × 0.5 × 0.2
1.73–23.97
Ϫ3 р h р 13, Ϫ18 р k р 18,
Ϫ23 р l р 24
12645
0.4 × 0.2 × 0.2
1.64–22.99
Ϫ38 р h р 38, Ϫ1 р k р 14,
Ϫ21 р l р 21
6522
Reflections collected
Independent reflections (Rint
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2σ(I)], R1, wR2
R indices (all data), R1, wR2
Largest difference peak, hole/e ÅϪ3
)
9931 (0.0096)
9221/0/866
1.112
0.0473, 0.1265
0.0645, 0.1602
1.934, Ϫ0.676
12593 (0.0097)
11557/0/937
1.203
0.1121, 0.3591
0.1364, 0.3914
2.844, Ϫ1.316
5876 (0.0488)
5416/0/475
1.087
0.0516, 0.0968
0.0781, 0.1062
1.506, Ϫ1.083
in methanol (0.939 g, 1 mmol). The yellow precipitate that
formed after 1 min was stirred for 4 h and then separated by
filtration, washed with diethyl ether and dried in vacuo. The
substance decomposes during storage and under heating, it is
soluble in methanol and slowly decomposes in chloroform
solution giving a precipitate of barium iodide. Yield 95%
(Found: C, 39.35; H, 3.20; N, 3.97. Calc. for C44H42BaFeI2-
N4P2Pt: C, 39.72; H, 3.18; N, 4.21%). IR (Nujol mull, cmϪ1):
3066w [ν(C–H)], 1523m, 1572w, 1586w (breathing pz), 526m,
507m, 447s, 441s [Cp–PPh2], 480vs, 472m (Cp tilt), 469s [ν(Fe–
Calc. for C88H84CdCl2Fe2N8O8P4Pt2: C, 48.25; H, 3.86; N,
5.4%). IR (Nujol mull, cmϪ1): 1529m, 1585w, 1573w (breathing
pz), 1095s (br) [ν(ClO4)], 516m, 508m, 495s, 446s [Cp–PPh2],
471m (Cp tilt). 1H NMR (CDCl3): δ 1.57 (br, 12 H, 3- or
5-CH3), 1.90 (br, 12 H, 3- or 5-CH3), 4.15 (br, 4 H, HCp), 4.37
(br, 4 H, HCp), 4.72 (br, 4 H, HCp), 5.02 (br, 4 H, HCp), 5.27 (br,
4 H, 4-CH), 7.00–8.00 (40 H, C6H5). 31P NMR (CDCl3):
δ ϩ2.38 [t, 1J(Pt–P) = 3249.6 Hz]. Λm (CH2Cl2, ΩϪ1 cm2 molϪ1):
53.9.
1
X-Ray crystallography
Cp)]. H NMR (CDCl3): δ 1.61 (s, 6 H, 3- or 5-CH3), 2.14 (s,
6 H, 3- or 5-CH3), 4.42 (d, 2 H, HCp), 4.48 (d, 2 H, HCp), 4.65
(d, 2 H, HCp), 4.73 (d, 2 H, HCp), 5.35 (s, 2 H, 4-CH), 7.60 (m),
7.73 (m), 7.95 (m), 8.05 (m) (20 H, C6H5).
Single crystals of the three compounds, L1, L2 and [(L1)CdI2],
were obtained by slow evaporation of the mixed solutions.
Diffraction data were collected on a STADI-4 (Stoe) for L1
and [(L1)CdI2] 5 and on a CAD-4 (Enraf-Nonius) four-circle
diffractometer for L2 (Mo-Kα radiation, graphite mono-
chromator). Unit cell parameters were obtained from 24
centered reflections. A summary of the crystallographic data
for these three compounds is provided in Table 1. In all cases
the absorption corrections were applied using ψ scanning data
for six–eight reflections. The structures were solved using direct
methods (SHELXS 86) and subsequent Fourier-difference
syntheses. The structures were refined anisotropically for all
non-hydrogen atoms using the SHELXL 93 program package.12
All hydrogen atoms were placed in calculated positions and
refined in a riding mode. The crystal of L2 was twinned and
thus the reflection intensities were strongly influenced by the
second component resulting in high R values and low accuracy
for this compound. Taking into account the presence of two
independent molecules, the mean values for the bond distances
and bond angles can be regarded as representative.
Bis{[1,1Ј-bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}zinc(II) tetrafluoroborate [(L2)2Zn]-
[BF4]2 15. Zinc() tetrafluoroborate hydrate (0.238 g, 1.0 mmol)
was added to a solution of L2 in methanol (1.880 g, 2.0 mmol).
The solution was stirred for 2 h and then diethyl ether (30 ml)
was added. A yellow-brown precipitate formed and was separ-
ated by filtration, washed with diethyl ether and dried in vacuo.
Yield 80%, mp 248–251 ЊC (Found: C, 49.5; H, 4.13; N, 5.70.
Calc. for C88H84B2F8Fe2N8P4Pt2Zn: C, 49.9; H, 4.0; N, 5.29%).
IR (Nujol mull, cmϪ1): 1529m, 1586w (breathing pz), 1090s
(br), 518s, 493s, 441s [Cp–PPh2], 471m (Cp tilt). 1H NMR
(CDCl3): δ 1.61 (br, 12 H, 3- or 5-CH3), 1.83 (br, 6 H, 3- or
5-CH3), 1.87 (br, 6 H, 3- or 5-CH3), 4.30–4.50 (br, 16 H, HCp),
5.2 (br, 2 H, 4-CH), 5.6 (br, 2 H, 4-CH), 7.00–8.00 (40 H,
1
C6H5). 31P NMR (CDCl3): δ ϩ1.94 [t, J(Pt–P) = 3174 Hz].
Λm (CH2Cl2, ΩϪ1 cm2 molϪ1): 49.2.
CCDC reference number 186/1124.
See http://www.rsc.org/suppdata/dt/1998/3335/ for crystallo-
graphic files in .cif format.
Bis{[1,1Ј-bis(diphenylphosphino)ferrocene]bis(3,5-dimethyl-
pyrazol-1-yl)platinum(II)}cadmium(II) perchlorate [(L2)2Cd]-
[ClO4]2 16. Cadmium() perchlorate hydrate (0.311 g, 1.0
mmol) was added to a solution of L2 in methanol (1.880 g, 2.0
mmol). A yellow precipitate immediately formed which was
stirred for 4 h, separated by filtration, washed by diethyl ether
and dried in vacuo. Recrystallized from chloroform–methanol.
Yield 78%, mp 265–266 ЊC (Found: C, 48.31; H, 3.9; N, 4.98.
Results and discussion
The reaction of the [1,1Ј-bis(diphenylphosphino)ferrocene]-
dichloroplatinum() derivative [(DPPF)PtCl2] with pzH, 3,5-
Me2pzH or 4-MepzH and potassium hydroxide in methanol
3338
J. Chem. Soc., Dalton Trans., 1998, 3335–3342

View Article Online
Table 2 Selected bond lengths and angles for L1, L2 and some platinum complexes containing azoles*
Bond lengths/Å
Bond angles/Њ
Compounda
L1
Pt–N
Pt–P
P–Pt–P
N–Pt–N
Ref.
2.04(1)
2.050(9)
2.05(1)
2.064(9)
2.02(3)
2.03(3)
2.273(2)
2.284(3)
2.276(3)
2.282(3)
2.270(9)
2.273(8)
2.267(9)
2.292(9)
2.229(2)
2.247(2)
98.3(1)
97.1(11)
84.8(4)
86.6(4)
This
work
L2
101.4(3)
97.6(3)
86.4(12)
88.1(10)
This
work
2.03(2)
2.06(2)
[Pt(dppe)2(3,5-Me2pz)2]
2.068(5)
2.050(5)
1.975(7)
1.990(7)
2.036(7)
2.006(9)
1.96(1)
86.75(7)
93.3(2)
89.0(3)
85.3(3)
22
23
24
25
[Pt(dmbipy)(3,5-Me2pz)2]
[Pt2(R3pz)2(Me2SO)2Cl]
[Pt2Cl2(µ-3,5-Me2pz)2(PMePh2)2]
2.216(4)
2.206(4)
84.7(4)
85.0(4)
1.99(1)
2.03(1)
2.04(1)
[Pt(dppe)2(3,5-Me2pz)][BF4]
2.107(5)
2.102(5)
1.983(4)
1.994(4)
2.002(4)
1.999(4)
2.004(4)
2.000(5)
2.091(5)
1.96(3)
2.245(2)
2.253(2)
84.87(6)
87.8(2)
26
[Pt(µ-pz)2(bipy)2][BF4]2
[Pt(µ-pz)2(pzH)2]2
83.6(2)
89.3(2)
91.5(2)
89.8(2)
89.1(2)
93.1(2)
27
28
[NBu4][Pt(C6F5)2(pzH)(pz)]
cis-[PtCl(PEt3)2L4][BF4]
29
30
2.28(1)
2.26(1)
98.0(4)
trans-[PtCl2(L5)2]
cis-[PtCl2(L6)2]
2.016(9)
2.029(5)
180
90.4
31
32
* dmbipy = 4,4Ј-dimethyl-2,2Ј-bipyridyl, L4 = indazole, L5 = 1-(2-nitroimidazol-1-yl)3-methoxypropanol, L6 = caffeine.
proceeds slowly to give the compounds L1 (az = pz), L2
(az = 3,5-Me2pz) or L3 (az = 4-Mepz) according to eqn. (1) in
MeOH
[(DPPF)PtCl2] ϩ 2KOH ϩ 2azH
[(DPPF)Pt(az)2] ϩ 2KCl ϩ 2H2O (1)
almost quantitative yield. The azole ligands were chosen in
order to vary the donor ability and the steric hindrance of
the ring (3,5-Me2pzH > 4-MepzH > pzH). The compounds
obtained give satisfactory elemental analyses and have been
characterized by IR, 1H, 13C-{1H} and 31P-{1H} NMR spectro-
scopy. Conductivity data and vaporimetric molecular weight
determinations indicate a non-ionic mononuclear structure in
solution with a P2N2 environment around the platinum center.
Fig. 1 PLUTO representations of the molecules L1 and L2.
In the 4000–400 cmϪ1 region the IR spectra of these mole-
cules exhibit weak vibrations due to C–H stretching modes of
the azolate rings at 3048–3100 cmϪ1, together with weak or
medium absorptions between 1500 and 1600 cmϪ1, typical of
ring breathing.13
cant distortion towards tetrahedral geometry although not
much significance should be attributed to the deviations from
the regular square planar coordination since in these com-
pounds the P–Pt–P angle is determined mainly by the con-
formation of the DPPF ligand. Although the crystal structures
presented here seem to be the first among the diaryl(ferrocene)-
platinum–azolate complexes known, they could be compared
with other bis(diphenylphosphine) compounds. Complexes
containing ferrocenylphosphine ligands have shown a peculiar
large bite resulting in quite large P–Pt–P angles,10,16–18 e.g.
103.68(6)Њ in [{DPPF}Pt(µ-H)(µ-CO)Pt{DPPF}].10 Whereas in
complexes containing the 1,2-bis(diphenylphosphine)ethane
donor (dppe) the P–Pt–P angle varies from 82.7(1)Њ in [Pt(dppe)-
In the far IR region the DPPF ligand gives rise to several
strong bands between 400 and 550 cmϪ1, due to y- and t-modes
of PPh2,14 to cyclopentadienyl ring tilt and to stretching of
Fe–Cp bonds.15
The PLUTO12 representations of the molecules and the
numbering schemes for L1 and L2 are given in Fig. 1, while
selected bond distances and angles are presented in Table 2.
Both structures consist of separate molecules containing biden-
tate DPPF ligand and two monodentate pyrazolate moieties
coordinated to Pt. In both structures two crystallographically
independent molecules are present which are nearly identical.
The Pt atom is square cis coordinated by two P atoms of DPPF
and two N atoms of pyrazolates [the Pt–P bond lengths range
from 2.267(9) to 2.292(9) Å while the Pt–N bond lengths are in
the range 2.02(3)–2.064(9) Å]. Both compounds show a signifi-
19
(µ-PPh2)2]2Cl2 to 85.1Њ in Fe2Pt(dppe)(CO)6(ButCP)20 and
86.7Њ in (dppe)PtCl2.21–22
On the other hand, the N–Pt–N angle is remarkably smaller
with respect to that in (4,4Ј-dimethyl-2,2Ј-bipyridyl)bis(3,5-
dimethylpyrazolyl)platinum() 89.0Њ,23 but is larger with
J. Chem. Soc., Dalton Trans., 1998, 3335–3342
3339

View Article Online
respect to other platinum()–pyrazolate derivatives {85.3Њ in
[Pt2(R3pz)2(Me2SO)2Cl]24 and 84.7Њ in [Pt2Cl2(µ-3,5-Me2pz)2-
(PMePh2)2]25}. This is also due to the steric properties of the
diphosphine ligand.
The platinum ferrocenylphosphine moiety can be viewed as
consisting of ferrocenophanes in the half chair conformation
with cyclopentadienyl rings staggered. The five-membered rings
do not deviate significantly from planarity.
In Table 2 the Pt–P and Pt–N bond distances are reported
also for some representative example of complexes of platinum
with azoles.22–33 The platinum–nitrogen bond lengths in L1
and L2 compare well with the literature data: they are slightly
shorter than in [1,2-bis(diphenylphosphino)ethane]bis(3,5-
dimethylpyrazolyl)platinum() (2.05–2.07 Å),22 a bit longer
with respect to such compounds as bis(µ-pyrazolato)bis(2,2Ј-
bipyridyl)platinum() bis(tetrafluoroborate)27 (1.98 Å) or [Pt2-
Cl2(µ-3,5-Me2pz)2(PMePh2)2]25 (1.96 Å) and similar to those in
[Pt2(R3pz)2(Me2SO)2Cl]24 (2.01–2.04 Å).
The Pt–P bond distances are slightly longer in comparison
to the values observed in a complex with 1,2-bis(diphenyl-
phosphino)ethane [2.229(2) and 2.247(2) Å],22 but they are very
close to those found in bis(diphenylphosphino)ferrocene com-
plexes and in the range expected for a phosphine trans to a
nitrogen.22–32
Fig. 2 PLUTO representation of molecule 5ؒ0.45CH2Cl2.
1
In the H NMR spectra of L1, L2 and L3, we found all the
expected signals due to azole and DPPF, suggesting that these
ligands have not undergone any structural change or
rearrangement upon coordination and ruling out structures
such as C-derivatives of a pyrazole. The integrations are in
accordance with the solid state structure.
The unstable barium() derivative 14 was obtained similarly
in high yield from methanol solution.
Whereas heteropentanuclear adducts (Fig. 2) were obtained
when the anion of the MЈX2 salts was a very weak nucleophile
such as BF4 or ClO4 [eqn. (3); az = L1, MЈ = Zn, X = BF4 15;
az = L1, MЈ = Cd, X = ClO4 16].
The Cp rings generally give rise to two broad doublets (ortho
and meta protons) in the region δ 4.20–4.40, whereas the proton
resonances of the azole and phenyl rings are in the region
δ 5.50–8.00. The assignment was often assisted by the appear-
ance of broad satellite bands due to coupling between hydrogen
and 195Pt. The 195Pt–1H couplings are observed only if the
number of intervening bonds is not greater than four. The
[(DPPF)Pt(az)2] ϩ MЈX2 →
[{(DPPF)Pt(az)2}2MЈ][X]2 (3)
All the adducts 1–13 have been isolated as fine yellow
powders: they are insoluble in methanol, water, diethyl ether
and aliphatic hydrocarbons are very soluble in acetone, DMSO
and chlorinated solvents. The latter solvents have a remarkable
tendency to be included in the crystals, likely fitting into the
holes of a crystal lattice in which the bulky inflexible 3,5-
dimethylpyrazolato ligands are present. Molar conductivities
in dichloromethane showed them to be non-electrolytes, thus
4
observed values for J(195Pt–1H) (ca. 10–15 Hz) agree with the
values found in literature.10
The 13C spectra show the three resonances for the Cp rings
(ipso, ortho and meta carbon atoms), with satellite bands due to
coupling with 195Pt. The 3J(Pt–C) and 4J(Pt–C), respectively, of
ca. 50 and 25 Hz are of the same order of magnitude as those
found in analogous diphosphine complexes.10,34 Coupling to
195Pt was also observed for the carbons of the azole rings and
for the ipso and ortho carbons of PPh2 moieties.
ruling out ionic structures such as [{(DPPF)Pt(az)2}2MЈ]2ϩ
[MX4]2Ϫ or ionic dissociation according to equilibrium (4).
-
The 31P NMR spectra of L1, L2 and L3 show a single reson-
ance at δ 7.87, 5.74 and 7.35 respectively (external reference
85% H3PO4) generally flanked by 195Pt satellites. The two phos-
phorus nuclei are magnetically equivalent and the signals
appear strongly deshielded with respect to that of the donor
Solvent
[(DPPF)Pt(µ-az)2MЈX2]
[(DPPF)Pt(µ-az)2MЈX]ϩ ϩ [X]Ϫ (4)
Vaporimetric molecular weight determination carried out on
selected derivatives indicates that these compounds are mono-
meric, ruling out dimeric DPPF- or halide-bridging structure.
No significant changes have been detected in their IR spectra up
to 400 cmϪ1 with respect to those of the proligands L1, L2 and
L3, however the presence of the MЈX2 moiety has been con-
firmed by the appearance in the range 350–120 cmϪ1 of medium
to strong ν(MЈ–X) absorptions.35,36 It is not possible to assign
the MЈ–N stretching vibrations because they are likely hidden
under some [(DPPF)Pt(µ-az)2] absorptions.
1
DPPF. The J(195Pt–31P) are in the range expected for a phos-
phorus trans to a nitrogen and increase with decreasing number
of methyl groups on the azole rings. From a comparison
between the 31P NMR chemical shifts of L1, L2 and L3 and
those previously reported for several [L–L]Pt(az)2 com-
pounds6–9 [L–L = bis(diphenylphosphino)alkane] correlations
between ring size and 31P NMR parameters analogous to
those reported for [L–L]PtR2 type complexes can be deduced
based on the ring contribution ∆r to the chemical shift.33–34
As previously indicated,33 shielding of the 31P NMR chemical
shift decreases in the order: dppm > DPPF > dppb > dppe
[dppb = 1,4-bis(diphenylphosphino)butane].
Compounds 15 and 16 are likely ionic not only in chlorinated
solution, as confirmed by conductance values, but also in the
solid state as evidenced by the presence of only one strong and
Ϫ
By reaction of the proligands L1, L2 and L3 with several zinc,
cadmium and mercury halides, stable 1:1 adducts were
obtained in accordance with reaction (2).
broad band at ca. 1090 cmϪ1 due to vibration of BF4 and
ClO4Ϫ ion respectively with tetrahedral symmetry.37
From the reaction between L1, L2 or L3 and CuX2 (X = Cl
or Br) in ethanol the compound [(DDPF)PtX2] was always
obtained upon scrambling of the anionic ligand X.11
MeOH and/or Et2O
[(DPPF)Pt(az)2] ϩ [MЈX2]
[(DPPF)Pt(µ-az)2MЈX2] (2)
1–13
A PLUTO view with the numbering scheme for trimetallic
compound [(LЈ)CdI2] 5 is given in Fig. 3, while selected bond
3340
J. Chem. Soc., Dalton Trans., 1998, 3335–3342

View Article Online
Table 3 Selected bond lengths (Å) and angles (Њ) for derivative
5ؒ0.45CH2Cl2
coordination. At 323 K all four signals coalesce in a broad
signal at ca. δ 4.35: the H NMR spectra of complexes 11 and
1
12, for example, are similar to that of the free [(DPPF)Pt(az)2]
donor in accordance with complete dissociation occurring only
at this temperature [eqn. (5)].
Pt–N(1)
Pt–N(3)
Pt–P(1)
Pt–P(1)
2.112(9)
2.052(9)
2.281(3)
2.273(3)
Cd–N(2)
Cd–N(4)
Cd–I(1)
Cd–I(2)
2.245(10)
2.248(10)
2.716(2)
2.748(2)
[(DPPF)Pt(µ-az)2MЈX2] →
N(3)–Pt–N(1)
N(1)–Pt–P(1)
N(1)–Pt–P(2)
N(3)–Pt–P(1)
N(3)–Pt–P(2)
P(2)–Pt–P(1)
86.9(4)
169.9(3)
87.7(3)
87.8(3)
169.6(3)
98.8(1)
N(2)–Cd–N(4)
N(2)–Cd–I(1)
N(2)–Cd–I(2)
N(4)–Cd–I(1)
N(4)–Cd–I(2)
I(1)–Cd–I(2)
88.1(3)
109.4(2)
109.1(2)
125.0(3)
105.0(3)
116.26(6)
[(DPPF)Pt(µ-az)2] ϩ MЈX2 (5)
The signals due to azole are generally displaced towards
lower field upon coordination, as already seen in zinc, cadmium
and mercury derivatives of analogous poly(pyrazolyl)alkanes.46
Nevertheless some exceptions are found; they concern one set
of methyl groups in the derivatives of L2, while the other set
in L2 follows the general trend, and the methyl group in the
4-position in L3 which is also displaced to higher field upon
coordination. A negligible shift was observed for H4 of deriv-
atives of L1. In any case the observed downfield shift of most of
the signals is additional evidence in favour of the existence of
the complexes in chloroform solution. We found that ∆δ (∆ =
difference in chemical shift of a given proton in the complex
and in the free ligand) lies between 0.51 and 0.01 ppm. The ∆δ
is generally greater for zinc() with respect to cadmium() and
mercury() derivatives.
It is also meaningful to compare the 31P NMR parameters of
L1, L2 and L3 with those of their Zn, Cd and Hg derivatives: the
1J(31P–195Pt) coupling constant always increases upon coordin-
ation, suggesting a stronger Pt–P bonding interaction in 1–16
than in their parent ligands. A similar trend was previously
observed in analogous derivatives of dppe.11
Fig. 3 Structure proposed for the pentanuclear derivatives 15 and 16.
On the other hand the 31P chemical shifts of derivatives of L1
and L3 remain almost unchanged upon coordination whereas
those of L2 are only slightly shifted to higher field, thus indicat-
ing that shielding of the 31P nucleus is not strongly dependent
on the coordination of the azole in the mono {[(DPPF)Pt(az)2]}
or exobidentate form {[(DPPF)Pt(µ-az)2MЈX2]}.
distances and angles are listed in Table 3. The geometry of
the ferrocenylphosphine moiety does not undergo substantial
changes that can be seen from comparison of the Pt–P dis-
tances and P–Pt–P angles with the corresponding values for
the donor molecules L1 and L2. The Cd atom is tetrahedrally
coordinated by two N-atoms of pyrazolate rings, that act as
exobidentate bridging ligands, and two iodine atoms [Cd–I
2.716(2) and 2.748(2) Å]. The low coordination number of
Cd in 5 can be compared with cadmium imidazole com-
plexes that are generally polymeric with a six-coordinated
cadmium atom. Thus in the structure of CdCl2(ImH) (ImH =
imidazole) the Cd atom is coordinated by five bridging chlorine
atoms and a monodentate imidazole molecule.38 In the bis-
(imidazole)dichlorocadmium complex the environment of
the metal atom contains four bridging chlorine atoms and
two monodentate ImH molecules.39 The low coordination
number of cadmium in 5 is likely due to the steric hindrance
of the 3,5-dimethylpyrazolate and iodine ligands. Only a few
examples of cadmium diiodo complexes with CN = 4 are
known, they include: diiodobis(p-toluidine)cadmium40 with
Cd–I 2.77 Å, (1,3-dimethylamino-2,2-dimethylpropane)diiodo-
cadmium (Cd–I 2.68–2.72 Å)41 and [{Fe2Cp2(CO)2(µ-CO)}2-
{µ5-CN(CH2)2NC}]CdI2 [Cd–I 2.7004(9) Å]42 all characterized
by very sterically hindered ligands.
We have also recorded 113Cd NMR spectra of deuteriated
chloroform solution on sufficiently soluble cadmium() deriv-
atives. In the spectra of 3 and 5 only a small resonance has been
found at δ 437 and 349 respectively which are typical of four-
coordinate cadmium species containing halide ligands.47
According to the conductance values these derivatives likely
possess in solution an N2CdX2 core, as in the solid state.
Although the poor solubility of the bromine derivative 4 pre-
vents us from drawing any relation between the 113Cd chemical
shift and halide substitution, it can be noted that on replace-
ment of chlorine by iodine a highfield displacement was
observed, in accordance with the trend reported for the
[R4N]2[CdX4] series (X = Cl, Br or I).47
Conclusion
We have prepared and fully characterized a series of plat-
inum() diphenylphosphinoferrocene complexes containing
azoles [(DPPF)Pt(az)2] and used X-ray crystallography and
NMR spectroscopy to examine how the ligand properties of
[(DPPF)Pt(az)2] are dependent on the steric and electronic fea-
tures of azH.
The Cd–N bonds in 5 could be compared with those in cad-
mium tris(pyrazolyl)amines43 (2.31–2.42 Å) or tris(pyrazolyl)-
borates44–45 (2.29–2.23 Å).
Surprisingly, the most important geometrical parameters of
the azole moiety in L1 and in 5 are the same. Thus, the N–Pt–N
angle in both structures is 87Њ, the distances between centroids
of two pyrazolyl rings are 4.44 Å in 5 and 4.43 Å, 4.46 Å in L1.
Obviously, the changes in the rigid ligand frame are very small
(e.g. the angle P–Pt–P is 98.8Њ in 5 and 97.1 and 98.3Њ in two
independent molecules of L1) in spite of the comparatively
low accuracy of structure determination in the case of L1.
Nevertheless, the average values are representative.
We have shown that it is possible to easily obtain hetero-
polymetallic complexes by using [(DPPF)Pt(az)2] species as
donors toward Zn, Cd, Hg and Ba acceptors, and also that the
nuclearity of the adducts synthesized is dependent on the
nucleophilic character of the counter ion employed: trinuclear
derivatives if the acceptor is a halide salt, pentanuclear deriv-
atives when the counter ion is a perchlorate or a tetrafluoro-
borate group. It is very interesting to compare our results with
those reported for poly(pyrazol-1-yl)alkanes.46 With the latter
ligands insoluble halide-bridging polynuclear derivatives have
been generally obtained whereas with the sterically hindered
[(DPPF)Pt(az)2] very soluble tetrahedral complexes, not only
In the 1H NMR spectra of derivatives 1–16 the Cp rings give
rise to four different broad doublets in the region δ 3.81–5.23
due to inequivalence of both ortho and meta protons upon
J. Chem. Soc., Dalton Trans., 1998, 3335–3342
3341

View Article Online
23 W. P. Schaefer, W. B. Connick, V. M. Miskowski and H. B. Gray,
Acta Crystallogr., Sect. C, 1992, 48, 1776.
24 V. Yu. Kukushkin, E. A. Alexandrova, V. M. Leovac, E. Z. Iveges,
V. K. Belsky and V. E. Konovalov, Polyhedron, 1992, 11, 2691.
25 V. K. Jain, S. Kannan and E. R. T. Tiekink, J. Chem. Soc., Dalton
Trans., 1993, 3625.
with mercury() and zinc() halide acceptors but also with
cadmium() halide ones, have been isolated.
Acknowledgements
Thanks are due to the University of Camerino and INTAS-
RFBR Foundation (grant No. 95-118) for financial support.
26 B. Bovio, G. Banditelli and A. L. Bandini, Inorg. Chim. Acta, 1985,
96, 213.
27 K. Sakai, T. Sato, T. Tsubomura and K. Matsumoto, Acta
Crystallogr., Sect. C, 1996, 52, 783.
28 W. Burger and J. Strähle, Z. Anorg. Allg. Chem., 1986, 539, 27.
29 G. López, J. Ruiz, C. Vicente, J. M. Martí, G. García, P. A.
Chaloner, P. B. Hitchcock and R. M. Harrison, Organometallics,
1992, 11, 4090.
30 J. L. Atwood, K. R. Dixon, D. T. Eadie, S. R. Stobart and
M. J. Zaworotko, Inorg. Chem., 1983, 22, 774.
31 N. Farrell, T. M. Gomes Carneiro, F. W. B. Einstein, T. Jones and
K. A. Skov, Inorg. Chim. Acta, 1984, 92, 61.
32 D. M. L. Goodgame, P. B. Hayman, R. T. Riley and D. J. Williams,
Inorg. Chim. Acta, 1984, 91, 89.
References
1 S. Trofimenko, Prog. Inorg. Chem., 1986, 34, 115.
2 G. Lopez, G. Garcia, J. Ruiz, G. Sanchez, J. Garcia and C. Vicente,
J. Chem. Soc., Chem. Commun., 1989, 1046.
3 G. Lopez, J. Ruiz, G. Garcia, C. Vicente, J. Casabò, E. Molins and
G. Miravittles, Inorg. Chem., 1991, 30, 2065.
4 F. Maury, J. Phys. IV, 1995, 5, C5-449.
5 R. Abul, M. B. Cleaver and J. S. Taylor, Inorg. Chem., 1992, 31,
3636.
6 G. Minghetti, G. Banditelli and F. Bonati, Chem. Ind. (London),
1977, 123.
7 G. Minghetti, G. Banditelli and F. Bonati, J. Chem. Soc., Dalton
Trans., 1979, 1851.
8 A. L. Bandini, G. Banditelli, G. Minghetti and F. Bonati, Can. J.
Chem., 1979, 57, 3237.
33 N. W. Duffy, C. J. McAdam, B. H. Robinson and J. Simpson, Inorg.
Chem., 1994, 33, 5343.
34 T. G. Appleton, M. A. Bennet and I. R. Tomkins, J. Chem. Soc.,
Dalton Trans., 1976, 439.
35 B. C. Cornilsen and K. Nakamoto, J. Inorg. Nucl. Chem., 1974, 36,
2467.
9 G. Banditelli, A. L. Bandini, F. Bonati and G. Minghetti, Inorg.
Chim. Acta, 1982, 60, 93.
36 C. Postmus, K. Nakamoto and J. R. Ferraro, Inorg. Chem., 1967, 6,
2194.
37 M. R. Rosenthal, J. Chem. Educ., 1973, 50, 331.
38 L. R. Nassimbeni and A. L. Rodgers, Acta Crystallogr., Sect. B,
1976, 32, 257.
39 R. J. Flook, H. C. Freeman and J. M. Rosalky, Acta Crystallogr.,
Sect. B, 1973, 29, 903.
40 R. N. Akatova, T. N. Tarknova and N. B. Belov, Kristallografiya,
1982, 27, 1187.
41 P. Richard, A. Boulanger, J. F. Guedon, W. J. Kasowski and
C. Bordeleau, Acta Crystallogr., Sect. B, 1977, 33, 1310.
42 S. Schroelkamp, W. Sperber, D. Lentz and W. P. Fehlhammer,
Chem. Ber., 1994, 127, 621.
43 G. J. Kleywegt, W. G. R. Weismeller, G. J. Van Driel, W. L. Driessen,
J. Reedijk and J. H. Noordik, J. Chem. Soc., Dalton Trans., 1985,
2177.
44 D. L. Reger, S. S. Mason and A. L. Rheingold, J. Am. Chem. Soc.,
1993, 115, 10 406.
45 D. L. Reger, S. S. Mason, J. Takats, Xing Wang Zhang, A. L.
Rheingold and B. S. Haggerty, Inorg. Chem., 1993, 32, 4345.
46 C. Pettinari, C. Santini, D. Leonesi and P. Cecchi, Polyhedron, 1994,
13, 1553.
10 A. L. Bandini, G. Banditelli, M. A. Cinellu, G. Sanna, G. Minghetti,
F. Demartin and M. Manassero, Inorg. Chem., 1989, 28, 404.
11 C. Pettinari, Main Group Met. Chem., 1995, 18, 183.
12 G. M. Sheldrick, SHELXS 86, Program for crystal structure
determination, University of Göttingen, 1986; G. M. Sheldrick,
SHELXL 93, Program for crystal structure refinement, University of
Göttingen, 1993; W. O. S. Motherwell and W. Clegg, PLUTO,
University of Cambridge, 1976.
13 G. Nieuwpoort, J. G. Vos and W. L. Groeneveld, Inorg. Chim. Acta,
1978, 28, 117.
14 K. Shobatake, C. Postmus, J. R. Ferraro and K. Nakamoto, Appl.
Spectrosc., 1969, 23, 12.
15 J. S. Bodenheimer and W. Lon, Spectrochim. Acta, Part A, 1973, 29,
1733.
16 D. A. Clemente, G. Pilloni, B. Corain, B. Longato and M.
Tiripicchio Camellini, Inorg. Chim. Acta, 1986, 115, L9.
17 T. Hoyashi, M. Konishi, Y. Kobori, M. Kumada, T. Higuchi and
K. Hirotsu, J. Am. Chem. Soc., 1984, 106, 158.
18 W. R. Cullen, T.-J. Kim, F. W. B. Einstein and T. Jones,
Organometallics, 1985, 4, 346.
19 A. J. Carty, F. Hartstock and N. J. Taylor, Inorg. Chem., 1982, 21,
1349.
20 S. I. Al-Resayes, P. B. Hitchcock, M. F. Meidine and J. F. Nixon,
J. Chem. Soc., Chem. Commun., 1984, 1080.
47 J. J. H. Ackerman, T. V. Orr, V. J. Bartuska and G. E. Maciel, J. Am.
Chem. Soc., 1979, 101, 341.
21 D. H. Farrar and G. Ferguson, J. Crystallogr. Spectrosc. Res., 1982,
12, 465.
22 B. Bovio, F. Bonati and G. Banditelli, Gazz. Chim. Ital., 1985, 115,
613.
Paper 8/05432K
© Copyright 1998 by the Royal Society of Chemistry
3342
J. Chem. Soc., Dalton Trans., 1998, 3335–3342