Platinum complexes having redox-active PPh2CCFc and/or CCFc as terminal or bridging ligands

Article abstract of DOI:10.1039/b822171e

A series of heteronuclear-Pt(ii) complexes containing ferrocenylethynyl units linked directly (Pt-CCFc) or through a phosphorous atom (Pt-PPh ₂CCFc) to the platinum center is reported. The reaction of derivative [cis-Pt(R_F)₂(PPh₂CCFc)₂] (R _F = C₆F₅) 1 with the solvate complex [cis-Pt(R_F)₂(thf)₂] leads to the formation of an asymmetrical heteronuclear diplatinum complex [{Pt(R_F) ₂(μ-1κP:2η²-PPh₂CCFc) ₂}Pt(R_F)₂] 9 having the "cis-Pt(R _F)₂" fragment coordinated to the triple bonds of both ferrocenylethynylphosphine units, while treatment of [cis-Pt(CCFc) ₂(PPh₂CCR)₂] (R = Fc 5a, Ph 5b, tBu 5c) with the same solvate [cis-Pt(R_F)₂(thf)₂], affords double ferrocenylacetylide-bridged diplatinum systems [{Pt(PPh ₂CCR)₂(μ-η¹:η²-CCFc) ₂}Pt(R_F)₂] 10. The solid-state structures of [cis/trans-Pt(R_F)₂(PPh₂CCFc)₂] 1/2, [cis-Pt(R_F)₂(PPh₂CCFc)(tht)] 3 (tht = tetrahydrothiophene), [{Pt(R_F)₂(μ-1κP: 2η²-PPh₂CCFc)₂}Pt(R_F) ₂] 9 and [{Pt(PPh₂CCtBu)₂(μ- η¹:η²-CCFc)₂}Pt(R_F) ₂] 10c have been determined by X-ray diffraction methods. The electronic spectra and the electrochemical behaviour of all monoplatinum derivatives are discussed, showing a different extent of interaction between the remote ferrocenyl groups when they belong to PPh₂CCFc or CCFc ligands. For the diplatinum systems 9 and 10, containing bridging (κP:η²-PPh₂CCFc 9) or (η¹: η²-CCFc 10) ligands, their electrochemical properties were also compared with the parent precursors.

Full text of DOI:10.1039/b822171e

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www.rsc.org/dalton | Dalton Transactions
∫
∫
Platinum complexes having redox-active PPh2C CFc and/or C CFc as
terminal or bridging ligands†
´
Alvaro D´ıez, Elena Lalinde,* M. Teresa Moreno* and Sergio Sa´nchez
Received 10th December 2008, Accepted 12th February 2009
First published as an Advance Article on the web 11th March 2009
DOI: 10.1039/b822171e
A series of heteronuclear-Pt(II) complexes containing ferrocenylethynyl units linked directly
∫
∫
(Pt–C CFc) or through a phosphorous atom (Pt-PPh2C CFc) to the platinum center is reported.
∫
The reaction of derivative [cis-Pt(RF)2(PPh2C CFc)2] (RF = C6F5) 1 with the solvate complex
[cis-Pt(RF)2(thf)2] leads to the formation of an asymmetrical heteronuclear diplatinum complex
2
∫
[{Pt(RF)2(m-1kP:2h -PPh2C CFc)2}Pt(RF)2] 9 having the “cis-Pt(RF)2” fragment coordinated to the
∫
triple bonds of both ferrocenylethynylphosphine units, while treatment of [cis-Pt(C CFc)2-
∫
(PPh2C CR)2] (R = Fc 5a, Ph 5b, tBu 5c) with the same solvate [cis-Pt(RF)2(thf)2], affords double
1
2
∫
∫
ferrocenylacetylide-bridged diplatinum systems [{Pt(PPh2C CR)2(m-h :h -C CFc)2}Pt(RF)2] 10.
∫
∫
The solid-state structures of [cis/trans-Pt(RF)2(PPh2C CFc)2] 1/2, [cis-Pt(RF)2(PPh2C CFc)(tht)] 3
2
∫
∫
(tht = tetrahydrothiophene), [{Pt(RF)2(m-1kP:2h -PPh2C CFc)2}Pt(RF)2] 9 and [{Pt(PPh2C CtBu)2-
1
2
∫
(m-h :h -C CFc)2}Pt(RF)2] 10c have been determined by X-ray diffraction methods. The electronic
spectra and the electrochemical behaviour of all monoplatinum derivatives are discussed, showing a
∫
different extent of interaction between the remote ferrocenyl groups when they belong to PPh2C CFc
2
∫
∫
or C CFc ligands. For the diplatinum systems 9 and 10, containing bridging (kP:h -PPh2C CFc 9)
or (h :h -C CFc 10) ligands, their electrochemical properties were also compared with the parent
1
2
∫
precursors.
On the other hand, although p-conjugated materials based
Introduction
on organophosphorous compounds have attracted considerable
interest as building blocks for the construction of molecular
electronic devices,46–51 studies of the electronic communication
mediated by alkynylphosphines are relatively scarce. As far as
we know, only a few reports of ruthenium complexes containing
∫
Alkynylphosphines PR3-n(C CR¢)n have been actively investigated
for many years, not only due to their wide versatility and
flexibility as polyfunctional ligands,1–17 but also because they
exhibit an interesting chemical reactivity when they are coor-
dinated to metal centers.1–4,10,17–45 Previous investigations have
shown that these ligands participate in P–C bond cleavage
and insertion or intramolecular coupling processes. In partic-
ular, in this area we10,38,39 and others28,40–43 have shown that
the proximity of two acetylenic groups on alkynylphosphine-
based complexes, induces intramolecular coupling reactions.
Thus, interesting m-2,3-bis(diphenylphosphino)-1,3-butadien-1-
52,53
54
∫
∫ ∫
PPh2C CPPh2
and PPh2C C–C CPPh2 ligands have been
reported.
In this area, multi-redox systems containing ferrocenyl groups
∫
as ethynyl capping moieties (C CFc) are currently a subject of
active research since they have interesting potential applications
in molecular electronic devices.55–84 In particular, employing
ferrocenylethynylphosphines, there are some recent interesting
contributions.45,85–88 One related with the successful generation of
the redox-active 1,2-diferrocenyl-3,4-diphosphinidenecyclobutene
=
=
yl, diphosphine bridging {m-C(R) C(PPh2)C(PPh2) C(R)(RF)}
=
=
and {m-C(RF) C(PPh2)C(PPh2) C(R)2} complexes are accessible
2
2
∫
from initial bis(h -alkyne) adducts [m-kP:h -(PPh2C CR)2] by
∫
ligand, starting from Mes*HP(C CFc) ligand (Mes* = 2,4,6-
10,38,39
∫
sequential insertion of two PPh2C CR into a Pt–C6F5 bond.
Furthermore, bis(phosphino)naphthalene moieties and/or chelat-
ing 1,2-diphosphinoalk-1-ene complexes were obtained by ther-
molysis or photolysis of [cis-Pt(C6F5)2(PPh2C CR)2] through a
[2 + 2 + 2] cycloaddition or activation of a P–C(Ph) bond,
respectively.44
tert-Bu3C6H2), which is subsequently coordinated to different
metal fragments.85 On the other hand, Baumgartner et al.
have reported the synthesis of polyferrocenylethynylphosphines
∫
PPh3-n(C CFc)n (n = 1–3),86 which have been also used to
∫
assemble hetero-multinuclear complexes of Pd(II), Pt(II) and
Au(I).86–88 These latter systems exhibit only single ferrocene-based
oxidation waves, taken by the authors as an indication of lack
of communication between the remote ferrocenyl groups on
ferrocenylethynylphosphine ligands.
Departamento de Qu´ımica-Grupo de S´ıntesis Qu´ımica de La Rioja,
UA-CSIC, Universidad de La Rioja, 26006, Logron˜o, Spain. E-mail:
elena.lalinde@unirioja.es; Fax: +34 941 299 621
† Electronic supplementary information (ESI) available: Extended struc-
tures of complexes 2·1.5CH2Cl2 (Fig. S1) and 3 (Fig. S2). Discussion and
Experimental section of the thermal behaviour of 9 and cyclic voltammo-
grams of complexes 4 (Fig. S3), 5a and 5c (Fig. S4) and 10a (Fig. S5).
CCDC reference numbers 713069–713073. For ESI and crystallographic
data in CIF or other electronic format see DOI: 10.1039/b822171e
As part of our research on the chemistry of alkynylphos-
phine ligands and our recent interest in ferrocenylethynyl plat-
inum complexes,89 the aim of this work was to investigate
the properties of platinum mononuclear complexes containing
ferrocenylethynyldiphenylphosphine and/or ferrocenylalkynide
groups and to examine their reactivity toward the solvate
3434 | Dalton Trans., 2009, 3434–3446
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[cis-Pt(RF)2(thf)2], which has been previously shown to inter-
in presence of CuI. Similar isomerizations of cis to trans alkynyl
Pt(II) complexes have been previously reported.90 It should be
noted that although thermal isomerizations are also known,91
in the case of cis 5a the complex remains unaltered by refluxing
it in toluene (2 h), thus confirming the catalytic role of the
CuI/NEt3 system. We note that when this work was finished,
Lang et al. reported the preparation and also the molecular
structure of 8 by the well known catalyzed (CuI) dehydro-
∫
∫
act easily with both PPh2C CR and alkynyl metal (M-C CR)
complexes. We report here the preparation and characterization
∫
∫
∫
of [cis/trans-Pt(RF)2(PPh2C CFc)2], [cis-Pt(RF)2(PPh2C CFc)X]
∫
∫
(X = tht, PPh2C CPh), [cis/trans-Pt(C CFc)2(PPh2C CFc)2]
∫
∫
and [cis-Pt(C CR)2(PPh2C CR¢)2] (R = Fc, R¢ = Ph, tBu;
R¢ = Fc, R = Ph, tBu) and we describe also the results of
∫
the reactivity of [cis-PtX2(PPh2C CR)2] (X = C6F5, R = Fc;
∫
∫
X = C CFc, R = Fc, Ph, tBu) towards [cis-Pt(RF)2(thf)2].
halogenation method starting from [cis-PtCl2(PPh2C CFc)2]
∫
Spectroscopic and electrochemical studies of the complexes
have revealed intriguing differences in transmitting electronic
interactions.
with excess of HC CFc in the presence of base
(HNiPr2).88
Complexes 1–8 were isolated as air and moisture stable solids
and were fully characterized by usual analytical and spectroscopic
means as well as single-crystal X-ray crystallography for 1, 2 and
Results and discussion
3 (see Experimental for details). It should be noted that the IR
-1
∫
spectra show n(C C) bands (2205–2156 cm ) due to the presence
Synthesis and characterization of monoplatinum compounds
∫
of P-coordinated PPh2C CR ligands, but only for complexes 5b
∫
The ferrocenylethynyldiphenylphosphine ligand (PPh2C CFc)
and 5c the expected bands due to terminal alkynyl groups are
was prepared according to the literature.86 The synthesis
observed (2136, 2116 cm-1 5b, 2133 cm-1 5c). The most remarkable
1
spectroscopic data correspond to the31P{ H} NMR spectra, which
of the monoplatinum complexes 1–8 is summarized in
∫
Scheme 1. Complexes [cis-Pt(RF)2(PPh2C CFc)2] 1, [trans-
show a singlet (1–3 and 5–8) or two different singlets (d -5.68,
-6.59 4) with 195Pt satellites. As expected, the value 1JPt–P coupling
constant in the cis-configured complexes 1, 3–7, (range 2322–2468
Hz) is lower than those observed in the trans derivatives, 2 and
8, (2832 and 2762 Hz, respectively), in agreement with the lower
∫
∫
Pt(RF)2(PPh2C CFc)2]
2 and [cis-Pt(RF)2(PPh2C CFc)(tht)]
3 were prepared with moderate (72% 1, 58% 2) or low (13%
3) yield, by displacement of tetrahydrothiophene ligand (tht)
∫
with PPh2C CFc on the corresponding adequate precursors,
[cis or trans-Pt(RF)2(tht)2]. In the same line, treatment of
trans influence of the phosphine ligands relative to the C6F5 or
8,11,12,38,39
∫
3 with additional PPh2C CPh ligand leads to the mixed-
∫
C CFc groups.
∫
∫
phosphine complex [cis-Pt(RF)2(PPh2C CFc)(PPh2C CPh)]
Details of crystallographic determinations for 1, 2 and 3 are
presented in Table 1 and selected bond distances and angles are
given in Table 2. The platinum centers in the complexes 1, 2
and 3 (Fig. 1) are located in a slightly distorted square-planar
(1, 3) or totally planar (2) environments with a cis (1, 3) or
trans (2) configuration and with unexceptional metric parameters
∫
∫
∫
4. cis-Bis(alkynyl) derivatives [cis-Pt(C CFc)2(PPh2C CR)2]
∫
(R = Fc 5a, Ph 5b, tBu 5c), [cis-Pt(C CR)2(PPh2C CFc)2]
(R = Ph 6, tBu 7) were also prepared in moderate yield by
displacement of the COD ligand from the adequate precursor
∫
[Pt(C CR)2(COD)] (R = Fc, Ph, tBu) by two equiv. of the
for this type of complexes.8,10–12,39–41,44,86,92 The P–Ca, Ca Cb bond
corresponding alkynylphosphine ligand. The trans derivative
∫
∫
∫
[trans-Pt(C CFc)2(PPh2C CFc)2] 8 was successfully synthesized
as an orange solid by refluxing 1 h the cis derivative 5a in NEt3
lengths and the angles P–Ca–Cb, Ca–Cb–Cg are also comparable
to those observed in related platinum complexes.10–12,39–41,43,44,86
Scheme 1
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Table 1 Crystal data and structure refinement parameters for complexes 1·CHCl3, 2·1.5CH2Cl2, 3, 9·2CH2Cl2 and 10c
1·CHCl3
2·1.5CH2Cl2
3
9·2CH2Cl2
10c
Empirical formula
Formula weight
T/K
C61H39Cl3F10Fe2P2Pt
1437.00
173(1)
0.71073
Monoclinic
C61.50H44Cl3F10Fe2P2Pt C40H27F10FePPtS
C74H42Cl4F20Fe2P2Pt2
2016.70
173(1)
0.71073
Monoclinic
C72H56F10Fe2P2Pt2
1674.99
100(1)
0.71073
Monoclinic
1448.05
173(1)
1011.59
173(1)
˚
l/A
0.71073
Monoclinic
C21/c
0.71073
Triclinic
P1
Crystal system
Space group
¯
P21/n
P21/a
P21/n
˚
a/A
20.3213(3)
13.3744(2)
21.9589(3)
90
110.0390(10)
90
5606.79(14)
4
1.702
23.2877(6)
11.0269(2)
23.3719(7)
90
93.8790(10)
90
9.7286(3)
11.8603(5)
17.0124(7)
78.501(2)
81.325(2)
69.772(2)
1797.75(12)
2
22.5130(7)
12.8900(3)
25.7752(8)
90
112.4820(10)
90
6911.3(3)
4
1.938
14.0670(2)
29.7506(5)
15.0209(3)
90
93.731(2)
90
6272.95(19)
4
1.774
˚
b/A
˚
c/A
a/◦
b/◦
g /◦
3
˚
V/A
5987.9(3)
4
Z
D
calcd/Mg m-3
1.606
2.928
1.869
4.475
m/mm-1
3.273
2824
4.747
3888
5.023
3264
F(000)
2856
984
Crystal size/mm3
2q range/◦
Index ranges
0.43 ¥ 0.38 ¥ 0.15
2.27–27.49
0 ≤ h ≤ 26
0 ≤ k ≤17
-28 ≤ l ≤ 26
12 763
0.4 ¥ 0.3 ¥ 0.1
3.21–25.68
-28 ≤ h ≤ 28
0 ≤ k ≤ 13
0 ≤ l ≤ 28
5667
0.4 ¥ 0.3 ¥ 0.25
4.09–26.02
-11 ≤ h ≤ 11
-14 ≤ k ≤ 14
0 ≤ l ≤ 21
6511
0.40 ¥ 0.375 ¥ 0.175
2.26–26.02
0 ≤ h ≤ 27
0 ≤ k ≤ 15
-31 ≤ l ≤ 29
13 582
0.20 ¥ 0.12 ¥ 0.07
2.72–26.02
-17 ≤ h ≤ 17
-36 ≤ k ≤ 36
-18 ≤ l ≤ 18
52 667
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness of fit on F2a
Final R indices [I > 2s(I)]a
12 763 [Rint = 0.0000] 5667 [Rint = 0.0000]
6511 [Rint = 0.0000]
6511/0/469
1.039
13 582 [Rint = 0.0000]
13 582/2/946
1.158
12 354 [Rint = 0.0932]
12 354/0/763
0.739
12 763/6/742
1.124
5667/2/381
1.155
R1 = 0.0483, wR2 =
R1 = 0.0437, wR2 =
R1 = 0.0384, wR2 = R1 = 0.0415, wR2 =
R1 = 0.0350, wR2 =
0.0786
0.0907
0.0955 0.0799
0.0420
R indices (all data)a
R1 = 0.0720, wR2 =
0.0881
R1 = 0.0641, wR2 =
0.0986
R1 = 0.0457, wR2 = R1 = 0.0545, wR2 =
R1 = 0.0773, wR2 =
0.0457
0.1005
0.0857
Largest diffraction peak and 1.681 and -1.209
1.789 and -0.528
2.101 and -1.102
1.273 and -1.152
1.373 and -1.032
-3
˚
hole e A
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
2
2
2
2
a R1 = (|Fo| - |Fc|)/ |Fo|; wR2 = [ w(Fo - Fc2)2/ wFo
]
1/2; Goodness of fit = { [w(Fo - Fc2)2]/(Nobs - Nparam)}1/2; w = [s (Fo2) + (g1P)2 +
g2P]-1; P = [max(Fo2; 0) + 2Fc2]/3.
◦
˚
˚
∫
Table 2 Selected distances (A) and angles ( ) for complexes 1·CHCl3,
2·1.5CH2Cl2 and 3
acetylenic units coupling, is 3.303(9) A. This value is comparable
˚
to those found in [cis-Pt(RF)2(PPh2C CPh)2] (3.20(2) A) and [cis-
39
˚
∫
Pt(RF)2(PPh2C CTol)2] (3.34(2) A), which undergo intramolec-
ular coupling of both alkynylphosphine ligands.44
1·CHCl3
2·1.5CH2Cl2
3
In complex 1, the cis-disposition allows the presence of p ◊ ◊ ◊ p
contacts involving the C6F5 ligands and the C(7–12) and C(31–
Pt–Pa
Pt–Pb
Pt–Ca
Pt–Cb
Pt–S
Pa–Ca
Pb–Ca¢
Ca–Cb
Ca¢–Cb¢
Pa–Pt–Pb
Pa–Pt–Ca
Ca–Pt–Cb
Pa–Pt–S
Pa–Ca–Cb
Pb–Ca¢–Cb¢
Ca–Cb–Cg
Ca¢–Cb¢–Cg ¢
2.288(2)
2.285(2)
2.068(5)
2.069(5)
—
1.760(6)
1.747(6)
1.197(7)
1.197(8)
93.12(5)
91.0(1)
87.2(2)
—
2.291(2)
—
2.068(5)
—
—
1.743(6)
—
1.199(8)
—
180.0(1)
90.24(15)
180.0(1)
—
171.9(5)
—
178.4(6)
—
2.286(2)
—
2.036(5)
2.075(5)
2.356(2)
1.742(6)
—
1.207(8)
—
—
89.0(2)
88.3(2)
92.02(6)
168.9(6)
—
178.2(7)
—
˚
˚
36) ph◦enyl ring◦s, (3.258(8) A, 3.118(9) A, interplanar angles
13.3(3) , 21.0(2) ; Fig. 1a).10,93,94,95 Aryl-pentafluorophenyl stack-
ing and pairing interactions play a prominent role in determining
supramolecular assemblies93 and have been also previously noted
as a driving force in many crystallizations.94,95 Complex 2 crys-
tallizes with one and a half molecules of dichloromethane in the
lattice. Inspection of the crystal packing reveals that each molecule
is connected to four neighbouring ones by p ◊ ◊ ◊ p interactions
˚
(3.18(2) A) between the C6F5 ligands and the Cp rings of the
179.4(5)
171.6(5)
178.3(6)
176.4(7)
ferrocenyl groups resulting in a bidimensional network along b
and c axis (Fig. S1a).† The layers are, additionally connected by
the solvent molecules through different types of contacts involving
one (Fig. S1b)† or three (Fig. S1c)† molecules of dichloromethane
˚
˚
The two cis-alkynylphosphine entities in the complex 1 are
found staggered, with a torsional angle Ca–Pa–Pb–Ca¢ of 65.0(3)◦,
(F(C6F5) ◊ ◊ ◊ H(CH2Cl2) 2.455(4) A, Cl(CH2Cl2) ◊ ◊ ◊ H(CH2Cl2) 2.495(8) A,
˚
C(Ph) ◊ ◊ ◊ H(CH2Cl2) 2.589(7) A), giving rise to a final three-dimensional
network. In the free solvent complex 3, secondary hydrogen bond-
ing interactions [H(C6H5) ◊ ◊ ◊ F(C6F5), F ◊ ◊ ◊ H–C(tht), F ◊ ◊ ◊ H–C(Fc), C(Fc)
H ◊ ◊ ◊ C(Ph), C(Ph)–H ◊ ◊ ◊ C(Fc), C(tht)–H ◊ ◊ ◊ C(C6F5) and C(Fc)–H ◊ ◊ ◊ H–
∫
slightly higher than those observed in [cis-MCl2(PPh2C CFc)2]
(M = Pt 56.2◦; M = Pd 56.7◦)86 but comparable to those
–
◦
∫
seen in related [cis-Pt(RF)2(PPh2C CR)2] (R = Ph 65.3(6) , Tol
68.9(6)◦, tBu 70.7(4)◦).39 It should be noted that the separation
C(Fc) (2.32–2.89 A)] and weak F(C6F5) ◊ ◊ ◊ C(Fc) (3.14(2) A) intermolec-
˚
˚
between the Ca atoms, which has been related to the ease of
ular contacts were also found (Fig. S2).†
3436 | Dalton Trans., 2009, 3434–3446
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∫
∫
∫
Fig. 1 Molecular structures of [cis-Pt(C6F5)2(PPh2C CFc)2] 1 (a), [trans-Pt(C6F5)2(PPh2C CFc)2] 2 (b) and [cis-Pt(C6F5)2(PPh2C CFc)(tht)] 3 (c).
Ellipsoids are drawn at the 50% probability level. Hydrogen atoms and crystallization solvents are omitted for clarity.
Reactivity of the monoplatinum complexes toward
[cis-Pt(C6F5)2(thf)2]
of the ferrocenyl substituent. This suggestion is also in line
2
∫
with the lower h -bonding capability of the bulky PPh2C CtBu
2
phosphine previously observed by us in related reactions.5 The h -
As we noted in the Introduction, binuclear platinum com-
plexes containing a m-2,3-bis(diphenylphosphino)-1,3-butadien-
bonding capability of these phosphines seems to follow the order
∫
∫
∫
PPh2C C(aryl) > PPh2C CFc > PPh2C CtBu. Aiming to induce
an insertion (into the Pt–C6F5 bond) or coupling process, the ther-
mal behaviour of 9 was also examined (see ESI).† Single crystals of
9 were easily grown by slow diffusion of n-hexane into a solution of
the crude solid in CHCl3 at -30 ◦C. The structure (Fig. 2, Table 3)
=
=
1-yl diphosphine bridging m-CR C(PPh2)C(PPh2) CR(RF) are
∫
∫
obtained by reaction of [cis-Pt(RF)2(PPh2C CR)(PPh2C CR¢)]
(R = R¢ = Ph, Tol; R = tBu, R¢ = Tol, Ph) with the solvate complex
[cis-Pt(RF)2(thf)2] (thf = tetrahydrofurane) through a sequential
38,39
∫
easy insertion of both PPh2C CR ligands into a Pt–C6F5 bond.
2
confirms the h coordination of the “Pt(RF)2” fragment to the
alkynyl bonds of the PPh2C CFc groups. Bimetallic complexes
stabilized by a double m-(PPh2C CR)2 are very rare
2
Evidence of the formation of bis(h -alkyne) adducts [{Pt(RF)2(m-
∫
2
∫
1kP:2h -PPh2C CR)2}Pt(RF)2] as initial transient species was
1,96–99
∫
and the
found by NMR spectroscopy at low temperature. Interestingly, the
insertion processes only take place when the alkynyl substituent
of at least one of the two phosphines is an electron-withdrawing
known examples involve a symmetrical coordination with the
phosphorous and the alkynyl unit bonded to each one of both
2
metal centers (m-1kP:2h )2. In 9, the coordination is asymmetrical
∫
aryl group (Tol, Ph). In fact, [cis-Pt(RF)2(PPh2C CtBu)2] did not
with the two identical moieties “cis-Pt(RF)2” showing a different
environment. The Pt(1) center retains its coordination to the P
atoms and the Pt(2) atom is bonded to both alkyne functions.
react with [cis-Pt(RF)2(thf)2] even under reflux conditions.38,39 In
contrast to these results, we have now found that treatment of
∫
the related orange complex [cis-Pt(RF)2(PPh2C CFc)2] 1 with [cis-
˚
As a consequence, the Ca–Cb distances (1.240(8), 1.218(8) A) are
Pt(RF)2(thf)2] in dichloromethane renders a bright red solution
considerably larger than those found in the precursor 1 (1.197(8),
2
from which the heteronuclear-diplatinum bis(h -alkynyl) complex
˚
∫
1.197(7) A) and the PPh2C CFc fragments are distorted from
2
∫
[{Pt(RF)2(m-1kP:2h -PPh2C CFc)2}Pt(RF)2] 9 was isolated as a
linearity (149.9(5)◦–164.3(5)◦). The distance between both Ca
red solid in very good yield (eqn (1)).
(1)
Complex 9 is only stable in the solid-state. Quite surprisingly, 9
dissociates in donor solvents such as acetone or tetrahydrofuran
in seconds in the corresponding starting precursors 1 and [cis-
Pt(RF)2(S)2] (S = thf, acetone) being only moderately stable in non-
donor solvents such CHCl3, CH2Cl2 or toluene. For instance, in
CDCl3, a solution of 9 at room temperature evolves slowly. Control
by 31P{ H} NMR reveals that after 3 h, the precursor 1 starts to
1
2
appear being the only phosphorous species in 4 d. It is remarkable
that at room temperature complex 9 does not evolve towards
insertion products, probably due to the electron-donor character
∫
Fig. 2 ORTEP diagram of [{Pt(C6F5)2(m-1kP:2h -PPh2C CFc)2}Pt(C6F5)2]
9. Ellipsoids are drawn at the 50% probability level. Hydrogen atoms and
CH2Cl2 molecules are omitted for clarity.
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◦
˚
Table 3 Selected distances (A) and angles ( ) for complexes 9·2CH2Cl2
and 10c
9·2CH2Cl2
Pt(1)–P(1)
Pt(1)–C(1)
C(37)–C(38)
Pt(2)–C(37)
Pt(2)–C(51)
2.304(2)
2.082(6)
1.240(8)
2.232(5)
2.179(5)
2.033(5)
94.21(5)
164.3(5)
164.1(6)
Pt(1)–P(2)
Pt(1)–C(7)
C(51)–C(52)
Pt(2)–C(38)
Pt(2)–C(52)
2.287(2)
2.065(6)
1.218(8)
2.272(5)
2.399(5)
2.032(6)
87.5(2)
Pt(2)–C(39)
Pt(2)–C(45)
P(1)–Pt(1)–P(2)
P(1)–C(37)–C(38)
C(37)–C(38)–C(53)
C(1)–Pt(1)–C(7)
P(2)–C(51)–C(52)
C(51)–C(52)–C(63)
149.9(5)
174.6(6)
10c
Pt(1)–P(1)
Pt(1)–C(37)
C(37)–C(38)
Pt(2)–C(61)
Pt(2)–C(37)
Pt(2)–C(40)
P(1)–Pt(1)–P(2)
Pt(1)–C(37)–C(38)
C(37)–C(38)–C(39)
2.270(2)
1.979(6)
1.228(6)
1.998(5)
2.282(5)
2.225(5)
96.34(5)
167.8(5)
168.3(5)
Pt(1)–P(2)
Pt(1)–C(40)
C(40)–C(41)
Pt(2)–C(67)
Pt(2)–C(38)
Pt(2)–C(41)
C(37)–Pt(1)–C(40)
Pt(1)–C(40)–C(41)
C(40)–C(41)–C(42)
2.277(2)
1.991(5)
1.219(7)
1.987(5)
2.307(5)
2.264(5)
77.8(2)
1
2
∫
∫
Fig. 3 Molecular structure of [{Pt(PPh2C CtBu)2(m-h :h -C CFc)2}Pt-
(C6F5)2] 10c. Ellipsoids are drawn at the 50% probability level. Hydrogen
atoms are omitted for clarity.
155.5(5)
161.5(5)
2
is formed by h coordination of the “cis-Pt(RF)2” fragment to both
ferrocenylalkynide ligands while the tertbutylethynylphosphine
ligands remain as terminal groups. The double ferrocenylalkynide
bridging system adopts a folded V-shaped disposition leading
˚
atoms (C(37) ◊ ◊ ◊ C(51) 2.918(8) A) decreases in comparison with
˚
the mononuclear compound 1 (3.303(9) A), a feature which could
explain the formation of the butadienyl complex 9¢ under thermal
conditions (see ESI).†
We and others have previously shown that s-alkynyl plat-
inum complexes are excellent precursors to homo- and hetero-
˚
to a relatively short Pt ◊ ◊ ◊ Pt separation (3.2236(3) A). The
˚
Pt–Ca,Cb bond distances (1.979(6)–1.991(5) A) and distortion of
2
∫
m-h -Ca CbFc bridging groups (see Table 3) are quite sim-
ilar to those found in the related derivative [(dppe)Pt(m-
100–105
C CPh)2Pt(RF)2].106 The Fc groups adopt a cisoid disposition and
∫
polymetallic complexes containing m-C CR ligands.
Gener-
∫
show similar torsion angles (44.8(2)◦ and 49.5(2)◦) with the Pt(1)
coordination plane, contrasting with the more disparate angles
found in complex 9 (52.5(2)◦ and 88.5(2)◦). The most relevant
spectroscopic feature of complexes 10 is found in the 19F spectra,
which exhibit the expected single set of five different fluorine
signals indicating that the ortho (and also the meta) endo and exo-
fluorine atoms of the C6F5 rings are non-equivalent. This indicates
that these molecules are relatively rigid on the NMR time scale,
contrasting with the usual fluxional behaviour previously found
in related homo- and hetero-bimetallic complexes stabilized by
double aryl or diarylacetylide bridging systems.5,100,106–110
ally, the preparation of these species is achieved by reaction of
platina-alkynyl substrates with a second metal (or salt) complex
containing labile ligands. In particular by starting from mixed
∫
∫
[cis-Pt(C CR)2(PPh2C CR)2] and the solvate [cis-Pt(RF)2(thf)2]
(molar ratio 1 : 1) only bimetallic double alkynyl bridged (m-
5
∫
∫
C CR)2 complexes were formed, indicating that the Pt–C CR
2
units have stronger h -bonding capability towards the relatively
hard and acid Pt(II) center than the alkynylphosphine P–C CR
∫
entities. In a similar way, as is shown in eqn (2), extension
∫
∫
of this reaction to [cis-Pt(C CFc)2(PPh2C CR)2] (5a–5c) allows
the access to heteronuclear-diplatinum asymmetrical complexes
1
2
∫
∫
[{Pt(PPh2C CR)2(m-h :h -C CFc)2}Pt(C6F5)2] (R = Fc 10a, Ph
10b, tBu 10c) stabilized by a chelating V-shaped double ferroceny-
lacetylide bridging system (see Experimental).
Optical properties
The UV-vis absorption spectra of all complexes 1–10 were
recorded in CH2Cl2 and the data are summarized in Table 4. The
∫
∫
absorption bands of HC CFc and free PPh2C CFc ligand are
also included for reference purposes. The low energy absorption
∫
∫
bands observed in HC CFc (336, 443 nm) and other M-C CFc
complexes have been previously assigned to 1IL p → p* and
1MLCT (M = Fe) transitions, respectively, with some mixture
of d–d character.89,111,112 In the free ligand PPh2C CFc, these
∫
low energy bands are seen slightly red-shifted (345, 446 nm),
due to the attachment of the PPh2 fragment. Complexes
1–10 display high-energy bands (l < 300 nm), assigned to
p–p* ligand centered transitions, and absorptions between 300–
(2)
Complexes 10 are isolated as orange-brown solids and have
been characterized by elemental analysis, IR, 1H, 19F and 31P{ H}
1
1
NMR spectroscopy and MALDI-TOF mass spectrometry. The
molecular structure of 10c has been also confirmed by an X-ray
diffraction study (Fig. 3, Table 3). As can be observed, complex 10c
400 nm, which are tentatively ascribed to an admixture of IL
1
∫
∫
(p → p* C CR, PPh2C CR, Fc) and MLCT transitions of type
∫
∫
(Pt(d) → PPh2C CR) and/or (dp(Pt) → p*(C CR)). Finally, the
3438 | Dalton Trans., 2009, 3434–3446
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Table 4 UV-vis absorption dataa
max./nm (103 e/M-1cm-1)
to the triple bonds of the ferrocenylethynylphosphines of the Pt(II)
∫
center lowers the energy of the p*C CFc based LUMO and,
Compound
l
consequently, the energy gap of the electronic transition.
In complexes 5–8, the presence of s-bonded alkynide ligands
(Pt–C CR) is particularly reflected in the higher values of
molar absorptivity (e) found for the bands observed in the 300–
∫
HC CFc
PPh2C CFc
1
2
236(49.4), 262(8.60), 270(7.77), 336(0.29), 443(0.33)
232(31.4), 275(14.95), 345(0.54), 446(0.43)
239(45.5), 282(23.1), 335(3.59), 358(sh, 1.62), 448(0.89)
231(46.7), 260(28.4), 287(20.8), 326(2.96), 360(sh, 1.22),
448(0.70)
235(40.6), 275(12.9), 283(12.4), 326(1.68), 358(sh, 0.62),
448(0.42)
∫
∫
400 nm range (see Table 4) due to additional contribution of
1
∫
mixed intraligand IL (p → p*(C CR)) and charge-transfer
3
1
113–115
∫
p(Pt) → p*(C CR) ( MLCT) transitions.
It is worth to
4
232(56.5), 264(30.8), 276(26.9), 324(2.49), 362(1.20),
448(0.89)
note that in the cis/trans isomers 5a and 8, the two bands
∫
∫
observed in the trans isomer [trans-Pt(C CFc)2(PPh2C CFc)2] 8
(333, 385 nm) are red-shifted with respect to the cis derivative
5a
5b
232(53.9), 275(26.4), 289(23.0), 317(12.7), 359(4.47),
444b(2.01)
230(81.0), 262(65.1), 277(50.9), 318(19.1), 371(5.79),
450(1.83)
230(62.6), 255(29.8), 319(15.0), 362(4.91), 446(1.19)
231(50.7), 270(31.3), 294(24.7), 354(5.16), 447(1.42)
230(46.9), 260(29.0), 309(17.9), 329(14.9), 448(2.10)
236(42.7), 267(25.7), 276(25.1), 333(9.61), 385(4.68),
448b(2.24)
237(45.6), 267(26.9), 287(17.5), 337(3.69), 479(1.44)
233(81.8), 279(41.5), 331(13.5), 365(7.63), 451b(3.13)
230(85.6), 260(62.8), 278(49.9), 310(18.5), 377(5.26),
461(2.33)
231(95.3), 276(33.2), 300(25.6), 340(13.0), 375(7.68),
458(3.69)
∫
∫
[cis-Pt(C CFc)2(PPh2C CFc)2] 5a (317, 359 nm), pointing to a
probably more effective p delocalization on the alkynide units
5c
6
7
8
∫
∫
(FcC C–Pt–C CFc) in the trans isomer 8, as has been previously
observed in other cis/trans configured bis(alkynyl)platinum(II)
complexes.113–117 The lowest energy band is seen in all s-alkynyl
complexes between 444–450 nm. No clear variation is observed
by modification of the phosphine (444 5a, 450 5b, 446 nm 5c) or
the substituent on the alkynyl group (444 5a, 447 6, 448 nm 7),
though the expected chromophore summation effect54,118 is slightly
reflected in the intensity of this band for complexes 5a and 8.
The most apparent feature in the visible region of the absorption
spectra of the diplatinum doubly-alkynyl bridged complexes 10a–
10c is that the broadening of the low energy band observed in the
precursors 5a–5c decreases slightly, giving rise to higher values of
e in complexes 10 (see Table 4).
9
10a
10b
10c
a CH2Cl2 at room temperature, ~5 ¥ 10-5 M. b Deconvolution of the low
energy band fits with two bands (~415 and 465 nm 5a; ~420 and 470 nm
8; ~438 and 462 nm 10a).
expected visible light absorption band (444–479 nm) due to the
presence of Fc groups is also observed in all derivatives. According
to previous assignments, this band is ascribed to the 1MLCT
transition (M = Fe) with some d–d character.89,111,112 In the C6F5-
containing complexes (1–4), the lmax of this band occurs at 448 nm
indicating that the influence of the co-ligands and the cis or trans
geometry of the ferrocenylethynylphosphine ligands in the charge-
Electrochemistry
The electrochemical properties of 1–10 were investigated by cyclic
voltammetry (CV) and differential pulse voltammetry (DPV).
Some of the voltammograms are depicted in Fig. 5, 6 and 7 and
Fig. S3–S5† and all the data are summarized in Table 5 together
∫
transfer transition of the remote C CFc moieties is negligible.
+
∫
∫
∫
with the Fc/Fc redox couple of HC CFc and PPh2C CFc. The
2
However, the h coordination of the “cis-Pt(RF)2” unit to complex
∫
cyclic voltammograms of free PPh2C CFc and HC CFc show one
reversible redox wave, on sweeping at anodic potential, at 0.61 V,
indicating a negligible influence of the change of H by the PPh2
fragment on the electronic properties of the Fc group. However,
1 leads to a remarkably red shift in the absorption maxima of this
band in the bimetallic complex 9 (448 nm 1, 479 nm 9, see Fig. 4).
2
This fact could be explained by assuming that the h coordination
∫
simple coordination of the PPh2C CFc ligand to the Pt center
induces a shift to higher potentials in both, pentafluorophenyl
Fig. 4 Electronic absorption spectra of selected complexes 1, 2 and 9 in
CH2Cl2. Inset corresponding to the corrected spectra of 1 (brown) and 9
(orange) showing the lowest energy band.
Fig. 5 Cyclic voltammogram of complexes 1 and 2 at a scan rate of
100 mV s-1.
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Table 5 Electrochemical data for the couple Fc/Fc+ for complexes 1–10a
1/2/V
E
E
pa/V
Epc/V
Kc
Fc/Fc+
0.46
0.61
0.61
0.72
0.71
0.73
0.72
0.49
0.65
0.66
0.78
0.79
0.79
0.79
—
0.42
0.56
0.55
0.66
0.63
0.68
0.67
—
0.32, 0.41
0.31, 0.40
0.62
0.65
0.28, 0.36, 0.64
0.64, 0.73
0.50, 0.57, 0.64
0.48, 0.59
0.51, 0.58
—
—
—
—
—
—
—
33
23
23
—
—
33
23
15
15
15
+
∫
∫
HC CFc/HC CFc
+
∫
∫
PPh2C CFc/PPh2C CFc
∫
[cis-Pt(C6F5)2(PPh2C CFc)2] 1
∫
[trans-Pt(C6F5)2(PPh2C CFc)2] 2
∫
∫
[cis-Pt(C6F5)2(PPh2C CFc)(tht)] 3
∫
[cis-Pt(C6F5)2(PPh2C CFc)(PPh2C CPh)] 4
0.37, 0.46, 0.64, 0.77b
0.37, 0.45
0.36, 0.44
0.68
∫
∫
[cis-Pt(C CFc)2(PPh2C CFc)2] 5a
∫
∫
[cis-Pt(C CFc)2(PPh2C CPh)2] 5b
0.42, 0.49
0.40, 0.48
0.74
∫
∫
[cis-Pt(C CFc)2(PPh2C CtBu)2] 5c
∫
∫
[cis-Pt(C CPh)2(PPh2C CFc)2] 6
∫
∫
[cis-Pt(C CtBu)2(PPh2C CFc)2] 7
0.70
0.75
∫
∫
[trans-Pt(C CFc)2(PPh2C CFc)2] 8
0.31, 0.40, 0.69
0.69, 0.77
0.54, 0.61, 0.73
0.55, 0.62
0.55, 0.62
0.37, 0.45, 0.74
0.73, 0.82, 0.91c
0.58, 0.64, 0.77
0.58, 0.65
0.59, 0.65
2
∫
[{Pt(C6F5)2(m-1kP:2h -PPh2C CFc)2}Pt(C6F5)2] 9
1
2
∫
∫
[{Pt(PPh2C CFc)2(m-h :h -C CFc)2}Pt(C6F5)2] 10a
1
2
∫
∫
2
[{Pt(PPh2C CPh)2(m-h :h -C CFc)2}Pt(C6F5)2] 10b
1
∫
∫
[{Pt(PPh2C CtBu)2(m-h :h -C CFc)2}Pt(C6F5)2] 10c
a All measurements were carried out in CH2Cl2 at 25 ◦C with NBu4PF6 0.1 M. Scan rate of 100 mV s-1 and vs Ag/AgCl reference electrode. b Measured
in the differential pulse voltammogram. c Tentatively assigned to an irreversible oxidation of a Pt center or a decomposition product.
Fig. 7 Cyclic voltammogram of 5c (red) and 10c (black) in CH2Cl2 at a
scan rate of 100 mV s-1. CV of 5c shows waves of by-products (*) due to
re-oxidation of electrogenerated fragments.
Fig. 6 Differential pulse voltammogram of 9 in CH2Cl2 at a scan rate of
10 mV s-1.
(1–4 0.71–0.73 V) and alkynyl (0.68 V 6 and 0.70 V 7) mononuclear
complexes, thus indicating that electron density is transferred to
the Pt(II) through the phosphorous atom, making the oxidation
of the Fe(II) centers more difficult. Similar anodic shifts were
case of complexes 1 (cis) and 2 (trans), the larger peak-to-peak
separation observed in the trans isomer (0.16 V 2 vs. 0.12 V 1)
point to the existence of some degree of electronic communication
between both Fc groups (Fig. 5). Similar conclusions relating the
extent of the electronic interaction between Fc groups with the
geometry of the molecule have been previously noted.63,130 Mixed
complexes 3 and 4 show different electrochemical properties,
despite of the presence of a single redox-active center in both
derivatives. Complex 3 displays a reversible wave at 0.73 V in
the cyclic voltammogram, whereas complex 4 displays a quasi-
reversible oxidation wave at similar potential (0.72 V) with both,
reduction and oxidation peaks proportional to the square root of
the scan rate (Fig. S3).†
∫
found by Baumgartner et al. in [MX2(PPh2C CFc)2] (M = Pt,
X = Cl; M = Pd, X = Cl, I; 0.60–0.64 V vs. SCE) complexes.86 It
is worthy to note that direct s-coordination of ferrocenylethynyl
groups not only to platinum but also to other metal centers
∫
([M]–C CFc) usually makes easier the oxidation of the Fc in
64,65,89,119–127
∫
relation to free HC CFc ligand.
This fact has been
attributed to some metal electron transference via p conjugation
and/or inductive effects. Therefore, the insertion of the PPh2
∫
∫
fragment on Pt–C CFc leading to Pt–PPh2-C CFc entities
clearly inhibits the possible electronic transference between Pt
and the Fc groups.
∫
∫
The CV and DPV of complex [cis-Pt(C CFc)2(PPh2C CFc)2]
5a, which present four redox centers, shows four unresolved waves
between 0.37 and 0.77 V (Fig. S4a).† The two first waves (0.37
and 0.46 V) are attributed to the sequential oxidation of the two
Fc groups of the ferrocenylacetylide ligands, in agreement with
Despite of the presence of two ferrocenyl groups in complexes
1–2 and 6–7, only one wave due to the simultaneous oxidation of
both Fc moieties was observed (0.72 V 1, 0.71 V 2, 0.68 V 6 and
0.70 V 7), suggesting a very weak or even null electronic interaction
between both ferrocenyl groups.128,129 Notwithstanding, in the
∫
similar values previously found not only in related [Pt(C CFc)2L2]
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1
(L = PPh3, dppe) complexes81 but also in derivatives 5b and 5c
2
(0.37, 0.45 V 5b; 0.36 and 0.44 V 5c). However, as is shown in
Fig. S4b,† both alkynylphosphine complexes (5b and 5c), exhibit
additional small peaks at higher anodic potentials, likely due to
electrochemically generated decomposition products, as has been
also previously observed in related cis-bis(ferrocenylacetylide) di-
or bis-(phosphine)platinum complexes.81,89 Taken into account this
behavior and the absence of electronic communication between
∫
the Fc groups in complex [cis-Pt(C6F5)2(PPh2C CFc)2] 1, the two
remaining peaks observed for complex 5a at 0.64 and 0.77 V are
likely due to overlapping of oxidation processes of Fc groups in
∫
PPh2C CFc ligands with those of decomposition products.
∫
∫
The trans derivative [trans-Pt(C CFc)2(PPh2C CFc)2] 8 dis-
plays two first reversible oxidation waves (0.31 and 0.40 V)
assigned, as in complexes 5, to the oxidation of the Fc groups
of both ferrocenylacetylide moieties and a higher oxidation peak
at 0.69 V due to the concomitant oxidation of the Fc groups
∫
in the PPh2C CFc ligands, confirming again that electronic
∫
∫
delocalization through C C–Pt–C C fragment is more favourable
∫
∫
than through C C–P–Pt–P–C C unit. The separations between
the waves (DE1/2 = E1/2(2) - E1/2(1) in mV at 298 K) observed in
complexes 5a, 5b, 5c and 8 allow to estimate the comproportion-
128,129
Fig. 8 Molecular structure of complex 9 showing the distance between
both C5H4 rings.
ation constants Kc
(~33 5a, 23 5b, 23 5c and 33 for 8).
Coordination of the “cis-Pt(RF)2” unit to the mononuclear com-
plexes 1 and 5 causes a significant change in their electrochemical
behaviour. Thus, in contrast to the simultaneous oxidation of both
ferrocenylacetylene fragments seems to reduce considerably the
electronic density on the p triple bond, and probably the interac-
tion of these with the ferrocenyl groups making more difficult their
oxidation. However, the observed values of DE1/2 (0.07 V 10) are
slightly smaller to those found in their precursors (0.09 V 5a; 0.08 V
5b, 5c). As can be seen in Fig. S5,† the cyclic voltammogram of
2
Fc groups in 1, in the diplatinum complex [{Pt(RF)2(m-1kP:2h -
∫
PPh2C CFc)2}Pt(RF)2] 9, two one-electron oxidation waves at 0.69
and 0.77 V are seen (Fig. 6). The separation of the waves (DE1/2
=
2
0.08 V) indicates that the h coordination of the “Pt(RF)2” to the
∫
P–C CFc alkynyl units could be suggestive of a weak electronic
1
2
∫
∫
complex [{Pt(PPh2C CFc)2(m-h :h -C CFc)2}Pt(RF)2] 10a shows
another two electron reversible wave at 0.73 V, ascribable to the
oxidation of both Fc groups of the ferrocenylethynylphosphine
ligands. The separation between the waves of the oxidation of the
Fc groups in 9 and 10a-10c (see Table 5) permit also to estimate
their comproportionation constants Kc.
communication between the Fc groups. An irreversible additional
small peak is observed at 0.91 V (Fig. 6ꢀ) probably due to a
metal (Pt) centered oxidation or to an electrochemically generated
species. It should be noted that although the C5H4 rings of both Fc
groups are not parallel (torsion angle 41.5(2)◦), they are relatively
˚
close (C(54) ◊ ◊ ◊ C(67) 3.429(9) A, Fig. 8) and therefore the existence
of some electronic delocalization in the partially oxidized species,
by the interaction of the co-facial p-orbitals of the Fc groups
cannot be excluded.131–135 The slight cathodic shift found in the
first oxidation of the diplatinum complex when compared to its
precursor (0.69 V 9 and 0.72 V 1) is surprising taking into account
the withdrawing effect of the “Pt(RF)2” fragment. A similar be-
haviour have been previously reported in other face to face stacked
ferrocenyl-containing derivatives, showing a lower value of the
potential of the first oxidation in the bimetallic species than in the
Conclusion
In conclusion, a series of heterometallic monoplatinum com-
plexes containing PPh2C CFc and/or C CFc as termi-
nal ligands has been synthesized and some of them em-
∫
∫
ployed as precursors of an unusual asymmetrical diplat-
2
∫
inum complex [{Pt(RF)2(m-1kP:2h -PPh2C CFc)2}Pt(RF)2] 9,
2
∫
containing two m-kP-h -PPh2C CFc bridging ligands and sev-
2
monoferrocenyl.131,132 In any case, due to the h coordination of the
eral doubly-ferrocenylethynyl bridging chelating-type (V-shape)
1
2
∫
∫
“Pt(RF)2” to the alkynylphosphine ligands, the degree of electronic
interaction either through the “Pt(RF)2” bridge or through-space
is larger than the found in the mononuclear precursor.
[{Pt(PPh2C CR)2(m-h :h -C CFc)2}Pt(RF)2] 10 complexes. Elec-
trochemical investigations have shown: (i) firstly, that the Fc-
centered oxidations are in general more favorable in the platina-
∫
∫
Surprisingly, different observation is found by comparing the
ferrocenylethynyl (Pt-C CFc) units than in the Pt-PPh2C CFc
entities; (ii) on the other hand, taking into account the separations
observed between the oxidation waves, the interaction between
the remote ferrocenyl groups in both, cis and trans configured
2
effect of h coordination of “cis-Pt(RF)2” to complexes 5. Thus,
1
2
∫
∫
complexes [{Pt(PPh2C CR)2(m-h :h -C CFc)2}Pt(RF)2] (R = Fc
10a, Ph 10b, tBu 10c) show two reversible waves (0.54, 0.61 V
10a; 0.55, 0.62 V 10b; 0.55, 0.62 V 10c) due to the consecutive
ferrocene-centered redox couples, which are anodically shifted in
relation to those observed in their corresponding precursors (0.37,
0.46 V 5a; 0.37, 0.45 V 5b; 0.36, 0.44 V 5c) (Fig. 7 for 5c/10c). In
these complexes, coordination of the “Pt(RF)2” unit to the platina-
∫
monoplatinum complexes, seem to be easier through the FcC C–
∫
∫
∫
Pt–C CFc units than through the FcC C–P–Pt–P–C CFc moi-
eties, pointing to a clear insulating role of the phosphorous atom
in the transference of electronic density and (iii) finally, it is
remarkable that the coordination of the “Pt(RF)2” fragment to
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Dalton Trans., 2009, 3434–3446 | 3441
©

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∫
Synthesis of [trans-Pt(C6F5)2(PPh2C CFc)2] 2
the ferrocenylethynyl or the ferrocenylethynylphosphine ligands
in the complexes 10a–10c and 9, respectively, causes a different
electrochemical response. Thus, a larger extent of electronic inter-
Complex 2 was prepared as an orange solid using the same method
described for 1, starting from [trans-Pt(C6F5)2(tht)2] (0.125 g,
action between the Fc groups is observed when the “Pt(RF)2” unit
∫
0.178 mmol) and PPh2C CFc (0.140 g, 0.355 mmol) (0.135 g,
2
∫
is h -coordinated to both PPh2C CFc ligands in complex 9,
58%). (Found: C 54.7, H 2.9. Calcd for C60H38F10Fe2P2Pt: C 54.7,
relative to its precursor 1, being the first oxidation slightly more
favourable (0.69, 0.77 V 9 vs. 0.72 V 1). In contrast, in complexes
10, having the “cis-Pt(RF)2” unit connected to the mutually cis
ferrocenylacetylide ligands, the oxidation of both Fc groups is
anodically shifted and the possible interaction between them seem
to be slightly reduced in relation to the precursors 5.
H 2.9%); IR nmax(Nujol)/cm◦-1 2161 (m) (C C), 779 (s) (C6F5 Xsens);
∫
dH (300.1 MHz; CDCl3; 20 C) 7.63 (m, 8H, Ph), 7.29 (m, 12H,
Ph), 4.52 (s, 4H, C5H4), 4.30 (s, 4H, C5H4), 4.23 (s, 10H, Cp);
dP (121.5 MHz; CDCl3; 20 ◦C) -6.70 (s, JPt-P 2832 Hz); dF
1
(282.4 MHz; CDCl3; 20 ◦C) -116.5 (dm, 4F, 3JPt-F ~ 238 Hz, o-F),
-162.8 (s, 2F, p-F), -164.3 (s, 4F, m-F); m/z (MALDI-TOF +)
+
+
∫
1318 (M 19%), 394 ([PPh2C CFc] 100).
Experimental
∫
Synthesis of [cis-Pt(C6F5)2(PPh2C CFc)(tht)] 3
All reactions were carried out under Ar using dried solvents
purified by known procedures and distilled prior use. IR spectra
were recorded on a FT-IR Nicolet Nexus spectrometer as Nujol
mulls between polyethylene sheets or KBr disks and NMR spectra
were recorded on a Bruker ARX 300 and on a Bruker Avance
400 spectrometer. Chemical shifts are reported in ppm relative to
external standards (SiMe4, CFCl3 and 85% H3PO4). Only complex
Complex 3 was obtained using a similar synthetic procedure
as 1, starting from [cis-Pt(C6F5)2(tht)2] (0.200 g, 0.284 mmol)
and 1 equiv. of PPh2C CFc. Its recrystallization from a mixture
∫
CH2Cl2–EtOH afforded 3 as an orange solid (0.035 g, 13% yield).
(Found: C 47.9, H 2.4. Calcd for C40H27F10FePPtS: C 47.6,
H 2.7%); IR nmax(Nujol)/cm-1 2167 (s) (C C), 802 (s), 785 (s)
∫
1 is enough soluble to register its 13C{ H} NMR spectrum.
1
(C6F5 Xsens); dH (300.1 MHz; CDCl3; 20 ◦C) 7.74 (m, 4H, Ph), 7.40
(m, 6H, Ph), 4.57 (s, 2H, C5H4), 4.35 (s, 2H, C5H4), 4.27 (s, 5H, Cp),
2.89 (m, 4H, a-CH2, tht), 1.73 (s, 4H, b-CH2, tht); dP (121.5 MHz;
Mass spectra (ES) were recorded on a HP 5989B and MALDI-
TOF spectra on a Microflex MALDI-TOF Bruker spectrometer
operating in the linear and reflector modes using dithranol as
matrix. Elemental analyses were carried out with a Perkin-Elmer
2400 CHNS/O microanalyzer. Cyclic voltammetry and pulse dif-
ferential were carried out in 0.1 M NBu4PF6 solutions as support-
ing electrolyte, using a three-electrode configuration (Pt disk as
working electrode, Pt-wire counter electrode, Ag/AgCl reference
electrode) and a Voltalab PST 050. The ferrocene/ferrocenium
couple served as internal reference (+0.46 V vs. Ag/AgCl). UV-
vis absorption spectra were recorded on a Hewlet-Packard 8453
◦
1
CDCl3; 20 C) -5.97 (s, JPt-P 2468 Hz); dF (282.4 MHz; CDCl3;
20 ◦C) -118.1 (m, 4F, 3JPt-F ~ 250, 197 Hz, o-F), -160.4 (t, 1F, p-F),
-162.8 (m, 2F, m-F), -163.1 (t, 1F, p-F), -164.5 (m, 2F, m-F); m/z
+
+
∫
(MALDI-TOF +) 1011 (M 21%), 923 ([Pt(C6F5)2(PPh2C CFc)]
38).
∫
∫
Synthesis of [cis-Pt(C6F5)2(PPh2C CFc)(PPh2C CPh)] 4
∫
To a solution of [cis-Pt(C6F5)2(PPh2C CFc)(tht)] (0.100 g,
0.099 mmol) in CH2Cl2 (20 cm ) was added PPh2C CPh (0.028 g,
0.099 mmol). After stirring for 1 h, the solution was evaporated to
dryness and the residue was treated with EtOH (~5 cm3), affording
4 as an orange solid (0.050 g, 42%). (Found C 55.3, H 2.8. Calcd
for C56H34F10FeP2Pt: C 55.6, H 2.9%); IR nmax(Nujol)/cm-1 2182
3
spectrometer. Literature methods were used to prepare the start-
ing materials cis/trans-[Pt(C6F5)2(tht)2],136 [Pt(C CPh)2(COD)],
∫
137
∫
106
89
138
∫
∫
∫
[Pt(C CtBu)2(COD)],
[Pt(C CFc)2(COD)], PPh2C CPh,
138
86
∫
∫
PPh2C CtBu and PPh2C CFc.
∫
(sh), 2166 (m) (C C), 795 (m), 782 (m) (C6F5 Xsens); dH (300.1 MHz;
∫
Synthesis of [cis-Pt(C6F5)2(PPh2C CFc)2] 1
CDCl3; 20 ◦C) 7.78–7.18 (m, 23H, Ph), 6.94 (d, 2H, Ph), 4.14 (s,
2H, C5H4),◦4.03 (s, 5H, Cp), 4.00 (s, 2H, C5H4); dP (121.5 MHz;
To a solution of [cis-Pt(C6F5)2(tht)2] (0.125 g, 0.178 mmol) in
1
1
3
CDCl3; 20 C) -5.68 (s, JPt-P 2466 Hz), -6.59 (s, JPt-P 2415 Hz);
∫
CH2Cl2 (20 cm ) at room temperature, was added PPh2C CFc
◦
3
dF (282.4 MHz; CDCl3; 20 C) -117.7 (dm, 2F, JPt-F ~ 315 Hz,
(0.140 g, 0.355 mmol). After 1 h of stirring, the solution was evap-
orated to dryness and treated with n-hexane (~5 cm3), affording 1
as an orange solid (0.168 g, 72%). (Found: C 54.8, H 2.9. Calcd
for C60H38F10P2Fe2Pt: C 54.7, H 2.9%); IR nmax(Nujol)/cm-1 2186
3
o-F), -118.2 (dm, 2F, JPt-F ~ 342 Hz, o-F), -162.8 (m, 1F, p-F),
-163.1 (m, 1F, p-F), -164.0 (m, 2F, m-F), -164.5 (m, 2F, m-F);
m/z (MALDI-TOF +) 1209 (M+ 100%).
∫
(m), 2165 (s) (C C), 797 (m), 774 (s) (C6F5 Xsens); dH (300.1 MHz;
CDCl3; 20 ◦C) 7.66 (m, 8H, Ph), 7.37–7.25 (m, 12H, Ph), 4.16 (s,
∫
∫
Synthesis of [cis-Pt(C CFc)2(PPh2C CFc)2] 5a
4H, C5H4),◦4.08 (s, 10H, Cp), 4.04 (s, 4H, C5H4); dP (121.5 MHz;
1
∫
To a solution of [Pt(C CFc)2(COD)] (0.173 g, 0.240 mmol) in
CDCl3; 20 C) -7.19 (s, JPt-P 2409 Hz); dF (282.4 MHz; CDCl3;
◦
3
3
∫
20 C) -117.7 (dm, 4F, JPt-F ~ 323 Hz, o-F), -162.8 (t, 2F, p-F),
-164.0 (m, 4F, m-F); dC (100.62 MHz; CDCl3; 20 ◦C) 145.6 (dm,
JC–F ~ 233 Hz, C6F5), 136.8 (dm, 1JC–F ~ 261 Hz, C6F5), 133.3 (d,
CH2Cl2 (20 cm ) was added PPh2C CFc (0.190 g, 0.480 mmol),
and the mixture was stirred for 1 h. The solution was concentrated
in vacuo (~2 cm3) and treated with n-hexane (~5 cm3), affording 5a
as an orange solid (0.121 g, 36%). (Found: C 61.4, H 4.3. Calcd
for C72H56Fe4P2Pt: C 61.7, H 4.0%); IR nmax(KBr)/cm-1 2182 (sh),
JC–P ~ 12.3 Hz, o-Ph), 132.6 (AXX¢, 3 lines pattern, |1JC–P + 3JC–P
~
66 Hz, i-Ph), 130.6 (s, p-Ph), 128.1 (m, m-Ph), 109.4 (AXX¢,
5 lines pattern, |2J(C–Ptrans) + J(C–Pcis) ~16 Hz|, C Cb), 90.4 (s, Ca C),
72.2 (s, C5H4), 70.1 (s, Cp), 69.7 (s, C5H4), 61.4 (s, i-C5H4); m/z
(ES +) 1318 (M+, 18%).
2157 (m) (C C); dH (300.1 MHz; CDCl3; 20 ◦C): 7.91 (m, 8H,
4
∫
∫
∫
Ph), 7.39 (m, 12H, Ph), 4.20 (s, 8H, C5H4), 4.02 (s, 20H, Cp),
3.98 (s, 4H, C5H4), 3.89 (s, 4H, C5H4); dP (121.5 MHz; CDCl3;
3442 | Dalton Trans., 2009, 3434–3446
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©

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◦
1
20 C) -7.28 (s, JPt-P 2346 Hz); m/z (ES +) 1402 (M+ 48%), 983
IR nmax(Nu◦jol)/cm-1 2177 (w), 2165 (m) (C C); dH (300.1 MHz;
CDCl3; 20 C) 8.14 (m, 8H, Ph), 7.47 (m, 12H, Ph), 4.55 (s, 4H,
C5H4), 4.24 (s, 4H, C5H4), 4.19 (s, 10H, Cp), 3.87 (s, 4H, C5H4),
3.84 (s, 10 H, Cp), 3.81 (s, 4H, C5H4); dP (121.5 MHz; CDCl3;
20 ◦C) -6.34 (s, 1JPt-P 2762 Hz); m/z (MALDI-TOF+) 1401 (M+
42%).
∫
+
∫
([Pt(PPh2C CFc)2] 100).
∫
∫
Complexes [cis-Pt(C CFc)2(PPh2C CR)2] (R = Ph 5b, tBu
5c) were prepared similarly as orange solids starting from
∫
∫
[Pt(C CFc)2(COD)] (0.150 g, 0.208 mmol) and PPh2C CPh
(0.119 g, 0.416 mmol) or [Pt(C CFc)2(COD)] (0.200 g,
∫
∫
0.277 mmol) and PPh2C CtBu (0.148 g, 0.554 mmol) with a
2
moderate (0.137 g, 56%, 5b) or good yield (0.250 g, 79%, 5c).
∫
Synthesis of [{Pt(C6F5)2(l-1jP:2g -PPh2C CFc)2}Pt(C6F5)2] 9
Data for 5b. (Found: C 64.5, H 4.1. Calcd for C64H48Fe2P2Pt:
C 64.8, H 4.1%); IR nmax(KBr)/cm-1 2175 (m), 2173 (sh), 2136
∫
solution of [cis-Pt(C6F5)2(PPh2C CFc)2] (0.108 g,
To
a
0.082 mmol) in CH2Cl2 (20 cm3) at -10 ◦C was added [cis-
Pt(C6F5)2(thf)2] (0.055 g, 0.082 mmol). The mixture was stirred
for 5 min and the solution was concentrated (~3 cm3) in vacuo and
treated with n-hexane (~5 cm3) affording 7 as a red solid (0.120 g,
79%). (Found: C 46.65, H 2.1. Calcd for C72H38F20Fe2P2Pt2: C
(w), 2116 (sh) (C C); dH (300.1 MHz; CDCl3; 20 ◦C) 7.90 (m,
∫
8H, Ph), 7.40–7.29 (m, 14H, Ph), 7.18 (t, 4H, Ph), 7.01 (d, 4H,
Ph), 4.02 (s, 10H, Cp), 3.96 ◦(s, 4H, C5H4), 3.89 (s, 4H, C5H4);
1
dP (121.5 MHz; CDCl3; 20 C) -6.74 (s, JPt-P 2337 Hz); m/z
(MALDI-TOF+) 1186 (M+ 100%).
46.8, H 2.1%); IR nmax(Nujol)/cm-1 2018 (s) (C C), 806 (m), 797
∫
(m) (C6F5 Xsens); dH (300.1 MHz; CDCl3; 20 ◦C) 7.46–7.24 (m, 20H,
Ph), 4.37 (s, 4H, C5H4), 3.87 (s, 10H, Cp), 3.73 (s, 4H, C5H4); dP
(121.5 MHz; CDCl3; 20 ◦C) 4.17 (s, 1JPt-P 2501 Hz); dF (282.4 MHz;
Data for 5c. (Found: C 62.6, H 5.0. Calcd for C60H56Fe2P2Pt:
C 62.9, H 4.9%); IR nmax(KBr)/cm-1 2205 (m), 2163 (s), 2133 (sh)
(C C); dH (300.1 MHz; CDCl3; 20 ◦C) 7.82 (m, 8 H, Ph), 7.37
∫
◦
CDCl3; 20 C) -113.6 (m, 2F, o-F), -115.2 (m, 2F, o-F), -118.0
(m, 12 H, Ph), 4.01 (s, 10 H, Cp), 3.95 (s, 4H, C5H4), 3.86 (s,
(m, 2F, o-F), -119.1 (dm, 2F, o-F), -159.5 (t, 2F, p-F), -161.2 (t,
4H, C5H4), 1.00 (s, 18H, tBu); dP (121.5 MHz; CDCl3; 20 ◦C)
2F, p-F), -161.8 (m, 2F, m-F), -162.9 (m, 2F, m-F), -164.5 (m,
1
-8.34 (s, JPt-P 2352 Hz); m/z (MALDI-TOF+) 1146 (M+ 16%),
+
∫
4F, m-F); m/z (ES +) 1152 ([Pt(C6F5)(PPh2C CFc)2] 100%), 986
+
+
∫
∫
∫
880 ([Pt(C CFc)2(PPh2C CtBu)] 22), 727 ([Pt(PPh2C CtBu)2]
+
∫
([Pt(PPh2C CFc)2] 18).
100).
1
2
∫
∫
Synthesis of [{Pt(PPh2C CFc)2(l-g :g -C CFc)2}Pt(C6F5)2] 10a
∫
∫
Synthesis of [cis-Pt(C CPh)2(PPh2C CFc)2] 6
∫ ∫
a solution of [cis-Pt(C CFc)2(PPh2C CFc)2] (0.110 g,
To
∫
To a suspension of [Pt(C CPh)2(COD)] (0.069 g, 0.136 mmol) in
0.078 mmol) in CH2Cl2 (20 cm3) at 0 ◦C was added [cis-
Pt(C6F5)2(thf)2] (0.052 g, 0.078 mmol). After 5 min of stirring,
the solution was evaporated to dryness and the brown residue
was treated with n-hexane (~5 cm3) affording 10a as a brown solid
(0.103 g, 68%). (Found: C 52.6, H 3.0. Calcd for C84H56F10Fe4P2Pt2:
C 52.3, H 2.9%); IR nmax(KBr)/cm-1 2180 (sh), 2159 (s), 2028 (w,
3
∫
CH2Cl2 (20 cm ) was added PPh2C CFc (0.108 g, 0.272 mmol),
and the mixture was stirred for 4 h. The solution was filtered
and the filtrate concentrated in vacuo (~2 cm3) and treated with
n-hexane (~5 cm3), affording 6 as an orange solid (0.035 g,
22%). (Found: C 64.95, H 4.0. Calcd for C64H48Fe2P2Pt: C 64.8,
H 4.1%); IR nmax(KBr)/cm-1 2182 (sh), 2156 (m) (C C); dH
∫
∫
br)◦(C C), 820 (m), 801 (m) (C6F5 Xsens); dH (300.1 MHz; CDCl3;
(300.1 MHz; CDCl3; 20 ◦C) 7.89 (m, 2H, Ph), 7.70 (m, 4H,
Ph), 7.53 (m, 4H, Ph), 7.48–7.01 (m, 20H, Ph), 4.21 (s,◦14H, Cp,
C5H4), 4.03 (s, 4H, C5H4); dP (121.5 MHz; CDCl3; 20 C) -6.59
20 C) 7.95 (m, 8H, Ph), 7.47 (m, 12H, Ph), 4.70 (s, 2H, C5H4),
4.31 (s, 2H, C5H4), 4.29 (s, 2H, C5H4), 4.25 (s, 4H, C5H4), 4.12 (s,
10H, Cp), 4.03 (s, 2H, C5H4), 3.99 (s, 10H, Cp), 3.75 (s, 2H, C5H4),
3.30 (s, 2H, C5H4); dP (121.5 MHz; CDCl3; 20 ◦C) -11.69 (s, 1JPt-P
(s, JPt-P 2350 Hz); m/z (MALDI-TOF+) 1186 (M+ 87%), 1084
1
+
+
∫
∫
∫
([Pt(C CPh)(PPh2C CFc)2] 40), 984 ([Pt(PPh2C CFc)2] 38).
◦
3
2849 Hz); dF (282.4 MHz; CDCl3; 20 C) -114.5 (m, 2F, JPt-F
~
3
406 Hz, o-F), -117.7 (m, 2F, JPt-F ~ 355 Hz, o-F), -164.5 (t, 2F,
p-F), -165.5 (m, 2F, m-F), -166.7 (m, 2F, m-F); m/z (MALDI-
TOF+) 1931 (M+ 12%), 1764 ([M - C6F5]+ 100).
∫
∫
Synthesis of [cis-Pt(C CtBu)2(PPh2C CFc)2] 7
∫
To a solution of [Pt(C CtBu)2(COD)] (0.059 g, 0.127 mmol) in
CH2Cl2 (20 cm ) was added PPh2C CFc (0.100 g, 0.253 mmol),
3
1
2
∫
∫
∫
Complexes
[{Pt(PPh2C CR)2(m-h :h -C CFc)2}Pt(C6F5)2]
and the mixture was stirred for 1 h. The solution was concentrated
in vacuo (~2 cm3) and treated with n-hexane (~5 cm3), affording 7
as an orange solid (0.042 g, 29%). (Found: C 62.85, H 4.95. Calcd
for C60H56Fe2P2Pt: C 62.9, H 4.9%); IR nmax(KBr)/cm-1 2178 (sh),
(R = Ph 10b, tBu 10c) were prepared similarly as orange-brown
∫
∫
solids starting from [cis-Pt(C CFc)2(PPh2C CPh)2] (0.076 g,
0.064 mmol) and [cis-Pt(C6F5)2(thf)2] (0.043 g, 0.064 mmol)
∫
∫
or [cis-Pt(C CFc)2(PPh2C CtBu)2] (0.120 g, 0.105 mmol) and
[cis-Pt(C6F5)2(thf)2] (0.071 g, 0.105 mmol) with a good yield
(0.081 g, 74%, 10b; 0.121 g, 69%, 10c).
2160 (s) (C C); dH (300.1 MHz; CDCl3; 20 ◦C) 7.82 (m, 8H, Ph),
∫
7.31 (m, 12H, Ph), 4.17 (s, 4H, C5H4), 4.15 (s, 4H, C5H4), 4.00 (s,
10H, Cp), 0.92 (s, 18H, tBu); dP (121.5 MHz; CDCl3; 20 ◦C) -6.39
Data for 10b. (Found:
C 52.85, H 3.0. Calcd for
(s, JPt-P 2322 Hz); m/z (MALDI-TOF+) 1145 (M+ 11%), 1064
1
C76H48F10Fe2P2Pt2: C 53.1, H 2.8%); IR nmax(KBr)/cm-1 2175
+
+
∫
∫
∫
([Pt(C CtBu)(PPh2C CFc)2] 6), 984 ([Pt(PPh2C CFc)2] 22).
∫
(s), 2034 (w), 2019 (w) (C C), 803 (m), 791 (m) (C6F5 Xsens); dH
(300.1 MHz; CDCl3; 20 ◦C) 7.97 (m, 8H, Ph), 7.45–7.26 (m, 14H,
Ph), 7.09 (t, 4H, Ph), 7.07 (d, 4H, Ph), 4.70 (s, 2H, C5H4), 4.11
(s, 2H, C5H4), 3.98 (s, 10H, Cp), 3.94 (s, 2H, C5H4), 3.30 (s, 2H,
C5H4); dP (121.5 MHz; CDCl3; 20 ◦C) -11.14 (s, 1JPt-P 2677 Hz); dF
(282.4 MHz; CDCl3; 20 ◦C) -114.2 (m, 2F, 3JPt-F ~ 375 Hz, o-F),
-117.6 (m, 2F, 3JPt-F ~ 454 Hz, o-F), -164.2 (t, 2F, p-F), -165.3 (m,
∫
∫
Synthesis of [trans-Pt(C CFc)2(PPh2C CFc)2] 8
∫ ∫
suspension of [cis-Pt(C CFc)2(PPh2C CFc)2] (0.100 g,
A
0.071 mmol) in NEt3 (~10 cm3) and CuI as catalyst was refluxed
for 1 h, precipitating 8 as an orange-brown solid (0.068 g, 68%).
(Found C 61.6, H 3.7. Calcd for C72H56Fe4P2Pt: C 61.7, H 4.0%);
This journal is
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©

View Article Online
2F, m-F), -166.5 (m, 2F, m-F); m/z (MALDI-TOF+) 1714 (M+
5 I. Ara, L. R. Falvello, S. Ferna´ndez, J. Fornie´s, E. Lalinde, A. Mart´ın
and M. T. Moreno, Organometallics, 1997, 16, 5923.
6 J. Fornie´s, E. Lalinde, A. Mart´ın, M. T. Moreno and A. J. Welch,
J. Chem. Soc., Dalton Trans., 1995, 1333.
+
5%), 1547 ([M - C6F5]+ 10), 1186 ([Pt(C CFc)2(PPh2C CPh)2]
∫
∫
100).
7 J. R. Berenguer, M. Bernechea, J. Fornie´s, J. Go´mez and E. Lalinde,
Organometallics, 2002, 21, 2314.
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Data for 10c. (Found:
C 51.45, H 3.5. Calcd for
C72H56F10Fe2P2Pt2: C 51.6, H 3.4%); IR nmax(KBr)/cm-1 2208 (m),
∫
2168 (s), 2034 (m), 1991 (w) (C C), 791 (s), 782 (s) (C6F5 Xsens);
dH (300.1 MHz; CDCl3; 20 ◦C) 7.88 (m, 8H, Ph), 7.52–7.45
(m, 12H, Ph), 4.65 (s, 2H, C5H4), 4.09 (s, 2H, C5H4), 3.97 (s,
10H, Cp), 3.93 (s, 2H, C5H4), 3.3◦0 (s, 2H, C5H4), 1.07 (s, 18H,
1
tBu); dP (121.5 MHz; CDCl◦3; 20 C) -13.31 (s, JPt-P 2690 Hz);
3
dF (282.4 MHz; CDCl3; 20 C) -114.4 (m, 2F, JPt-F ~ 369 Hz,
3
o-F), -117.4 (m, 2F, JPt-F ~ 465 Hz, o-F), -164.5 (t, 2F, p-F),
-165.5 (m, 2F, m-F), -166.6 (m, 2F, m-F); m/z (MALDI-TOF+)
13 D. A. J. Harding, E. G. Hope, J. Fawcett and G. A. Solan, J. Organomet.
+
+
Chem., 2007, 692, 5474.
∫
1674 (M 4%), 727 ([Pt(PPh2C CtBu)2] 84).
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3918.
X-Ray crystallography
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Orange crystals of 1, 2, 3, 9 and 10c suitable for X-ray diffraction
were grown by slow diffusion of n-hexane into CHCl3 (1, 9),
CH2Cl2 (2, 10c) or acetone (3) solution of each compound at
low temperature (-30 ◦C). For complex 1·CHCl3, one molecule
of CHCl3 is present in the asymmetric part of the unit cell and
it is disordered over two sets of positions with partial occupancy
0.6/0.4. For 2·1.5CH2Cl2, 0.75 molecules of CH2Cl2 were found in
the asymmetric part of the unit cell, and for 9·2CH2Cl2, 2 molecules
of CH2Cl2, which were adequately modelled. X-ray intensity data
were collected with a NONIUS-kCCD area-detector diffractome-
ter (1, 2, 3 and 9) or an Oxford Diffraction Xcalibur CCD diffrac-
tometer (10c), using graphite-monochromated MoKa radiation.
Images were processed using the DENZO and SCALEPACK suite
of programs,139 carrying out the absorption correction at this point
for complexes 1·CHCl3 and 9·2CH2Cl2. The diffraction frames for
complex 10c were integrated and corrected for absorption using
the Crysalis RED package.140 The absorption correction was per-
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(10c). The structures of 1·CHCl3, 2·1.5CH2Cl2, 9·2CH2Cl2 and
10c were solved by Direct Methods, while complex 3 was solved
by Patterson, using SHELXS-97.143 The structures were refined
by full-matrix least squares on F2 with SHELXL-97,144 and
all non-hydrogen atoms were assigned anisotropic displacement
parameters. The hydrogen atoms were constrained to idealized
geometries fixing isotropic displacement parameters 1.2 times the
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-3
˚
present some residual peaks greater than 1 e A , but with no
35 M. A. Bennett, C. J. Cobley, A. D. Rae, E. Wenger and A. C. Willis,
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chemical meaning.
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Acknowledgements
This work was supported by the Spanish Ministerio de Cien-
cia e Innovacio´n and fondos FEDER (“Grupo Consolidado”
CTQ2008–06669-C02/BQU and a grant for A. D´ıez). S. Sa´nchez
thanks the C.S.I.C. for a grant.
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