Platinum(0) complexes with alkynylphosphane ligands

Article abstract of DOI:10.1002/ejic.201200265

The reactivity of the Pt⁰ derivative [Pt₂(dba) ₃] (dba = trans,trans-dibenzylideneacetone) towards PPh ₂C≡CR [R = Ph, tolyl (Tol), C₅H₄N-2] and PPh₂C≡CPPh₂ (dppa) has been explored. Treatment of [Pt₂(dba)₃] with PPh₂C≡CR (8 equiv.) in THF gave the tetrahedral complexes [Pt(PPh₂C≡CR)₄] [R = Ph (1), Tol (3), C₅H₄N-2 (5)], whereas reactions with a molar ratio of 1:4 afforded the binuclear derivatives [{Pt(PPh ₂C≡CR)(μ-κP:I·²-PPh ₂C≡CR)}₂] [R = Ph (2), Tol (4) X-ray, C ₅H₄N-2 (6)], which were shown to be generated through the mononuclear complexes 1, 3 and 5 as intermediate species. An analogous reaction using 4 equiv. of PPh₂C≡CPPh₂ afforded [Pt ₂(PPh₂C≡CPPh₂)₂(μ- κ²PP'-PPh₂C≡CPPh₂)₃] (7), in which two Pt(PPh₂C≡CPPh₂) fragments are joined through three bridging dppa ligands (μ- κ²PP'-PPh₂C≡CPPh₂). Attempts to crystallize 7 at -30 °C afforded crystals of [Pt₂{PPh ₂C≡CP(O)Ph₂}₂(μ- κ²PP'-PPh₂C≡CPPh₂)₃] (8) by oxidation of the free end of the terminal dppa ligands. The compound was characterized by X-ray diffraction. Tetrahedral Pt⁰ complexes [Pt(PPh₂C≡CR)₄], which evolve into binuclear derivatives [{Pt(PPh₂C≡CR)(μ-κP: I·²-PPh₂C≡CR)}₂] [R = Ph, tolyl, C₅H₄N-2], and binuclear compounds stabilized by a (μ-PPh₂C≡CPPh₂)₃ triply bridging system have been prepared and fully characterized. Copyright

Full text of DOI:10.1002/ejic.201200265

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DOI: 10.1002/ejic.201200265
Platinum(0) Complexes with Alkynylphosphane Ligands
Jesús R. Berenguer,[a] Elena Lalinde,*[a] M. Teresa Moreno,*[a] and Patricia Montaño[a]
Keywords: Platinum / Bridging ligands / Phosphane ligands / Homometallic complexes / Alkynes
The reactivity of the Pt0 derivative [Pt2(dba)3] (dba
=
ate species. An analogous reaction using 4 equiv. of
PPh2CϵCPPh2 afforded
[Pt2(PPh2CϵCPPh2)2(μ-κ2PPЈ-
trans,trans-dibenzylideneacetone) towards PPh2CϵCR [R =
Ph, tolyl (Tol), C5H4N-2] and PPh2CϵCPPh2 (dppa) has been
explored. Treatment of [Pt2(dba)3] with PPh2CϵCR (8 equiv.)
in THF gave the tetrahedral complexes [Pt(PPh2CϵCR)4] [R
= Ph (1), Tol (3), C5H4N-2 (5)], whereas reactions with a molar
PPh2CϵCPPh2)3] (7), in which two “Pt(PPh2CϵCPPh2)” frag-
ments are joined through three bridging dppa ligands (μ-
κ2PPЈ-PPh2CϵCPPh2). Attempts to crystallize 7 at –30 °C af-
forded crystals of [Pt2{PPh2CϵCP(O)Ph2}2(μ-κ2PPЈ-PPh2Cϵ
CPPh2)3] (8) by oxidation of the free end of the terminal dppa
ligands. The compound was characterized by X-ray diffrac-
tion.
ratio
of
1:4
afforded the
binuclear
derivatives
[{Pt(PPh2CϵCR)(μ-κP:η2-PPh2CϵCR)}2] [R = Ph (2), Tol (4) X-
ray, C5H4N-2 (6)], which were shown to be generated
through the mononuclear complexes 1, 3 and 5 as intermedi-
tems. In addition, we have reported several mixed-valence
PtII–Pt0 complexes stabilized by one (μ-PPh2CϵCR) [R =
Ph, tolyl (Tol), C6H4CϵCPh] bridging alkynylphos-
phane,[44] and we have also demonstrated an efficient and
easy sequential insertion of two PPh2CϵCR (R = Ph, Tol)
ligands into the robust Pt–C6F5 bond.[5,6,8]
Despite the coordinative possibilities of these ligands,
only a few examples are known in which alkynylphosphane
ligands are coordinated to Pt0 centres,[18,44,48–50] and those
that have been structurally characterized are particularly
scarce.[18,44,49] It is therefore of interest to investigate plati-
num(0) complexes that contain alkynylphosphane
Introduction
Alkynylphosphanes PR3–n(CϵCRЈ)n are polyfunctional
ligands that show versatile behaviour in coordination chem-
istry.[1,2] Although P coordination is commonly kinetically
favoured,[3–13] they can act as a bridging ligand through the
phosphorus and the triple bond.[3,4,7,8,10–12,14–16] Only a few
examples are known in which alkyne coordination is fav-
oured, usually with metals in low oxidation states.[17–19] As
expected, linear bis(phosphane)poly-ine [PPh2(CϵC)nPPh2]
ligands have been demonstrated to offer higher coordina-
tion and to generate on occasion chains, rings or poly-
mers.[14,20–24]
(PPh2CϵCR)
and
bis(diphenylphosphanyl)acetylene
Furthermore, alkynylphosphanes have shown an interest-
ing reactivity in transition-metal chemistry including (i) in-
sertion into reactive M–H or M–C bonds;[5,6,8,25–29] (ii) in-
tramolecular coupling reactions;[5,6,8,14,21,23,30–32] (iii) P–
C(alkyne) bond cleavage processes to afford alkynyl (CϵC)
and phosphide (PPh2) fragments,[15,33–37] which are often
involved in subsequent coupling or insertion reactions;[38–40]
and (iv) activation of the uncoordinated alkyne function
upon simple P coordination toward electrophilic or nucleo-
philic attacks.[9,17,18,41–43]
(PPh2CϵCPPh2) ligands.
Results and Discussion
To investigate the behaviour of alkynylphosphane ligands
with Pt0, the reactions of the precursor [Pt2(dba)3] with
PPh2CϵCR (R = Ph, Tol, C5H4N-2) were explored
(Scheme 1). Treatment of [Pt2(dba)3] in tetrahydrofuran at
room temperature with the corresponding PPh2CϵCR li-
gand in 1:8 molar ratio over 2 h led to the formation of
the Pt0 derivatives [Pt(PPh2CϵCR)4] [R = Ph (1), Tol (3),
C5H4N-2 (5)] (Scheme 1, i), which were isolated as yellow
solids after usual workup. In the cases of 1 and 3, the solids
obtained were impure, with small traces of the free
PPh2CϵCR and the binuclear derivatives [{Pt(PPh2Cϵ
CR)(μ-κP:η2-PPh2CϵCR)}2] [R = Ph (2), Tol (4)], as ob-
served by 31P{1H} NMR spectroscopy, so they had to be
recrystallized from THF/n-hexane. Longer periods of reac-
tion times increased the formation of the binuclear deriva-
tives 2 or 4. It should be noted that the related complex
In this area we have described several homo- and hetero-
metallic PtII derivatives that contain (μ-PPh2CϵCR)(μ-X)
[X = Cl,[3,11,12] CϵCRЈ,[4] CϵC–C6H4–CϵCPh,[10] tetra-
hydrothiophene (tht),[7,44] o-C6H4E2 (E = O, S)[8]], (μ-
[45]
PPh2CϵCFc)2 or (μ-dppa)n (n = 1, 2)[46,47] bridging sys-
[a] Departamento de Química-Grupo de Síntesis Química de La
Rioja, UA-CSIC, Universidad de La Rioja,
26006 Logroño, Spain
Fax: +34-941299621
E-mail: elena.lalinde@unirioja.es
teresa.moreno@unirioja.es
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J. R. Berenguer, E. Lalinde, M. T. Moreno, P. Montaño
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Scheme 1. Synthetic pathways for the synthesis of complexes 1–8.
[Pt(PPh2CϵCCH3)4] has been previously reported,[50] the (ca. 1 min), complex 3 was initially formed and was the only
nature of which was established by spectroscopic evidence product observed together with a small amount of PPh2(O)-
1
(IR, H NMR and UV/Vis).
CϵCTol (always present). Over time, the signals due to 3
With the aim of obtaining the binuclear derivatives 2, 4 decreased, whereas those of 4 gradually increased and after
and 6, the reactions between [Pt2(dba)3] and PPh2CϵCR 6 h; 4 and 3 were present in an approximate ratio of 3:1
were carried out in THF at room temperature in a 1:4 mo- (4:3). After 24 h, 3 had disappeared and 4 was the only
lar ratio, thereby affording [{Pt(PPh2CϵCR)(μ-κP:η2- platinum-containing product in the reaction medium. This
PPh2CϵCR)}2] [R = Ph (2), Tol (4), C5H4N-2 (6)] result clearly indicates that the tetracoordinate complexes
(Scheme 1, ii) as pure solids. Control by 31P{1H} NMR seem to be the kinetic initially formed products, which grad-
spectroscopy (CDCl3) of the reaction that led to 4 in THF ually evolve into the thermodynamic more stable tricoord-
revealed that the formation of the binuclear products takes inate diplatinum derivatives. In fact, pyridin(alkynyl)phos-
place through the mononuclear [Pt(PPh2CϵCR)4] deriva- phane 5 evolved into a mixture of 6 and free phosphane by
tives (Scheme 1, iii). Thus, after the addition of phosphane stirring the complex in toluene over four days (Scheme 1,
2
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Pt0 Complexes with Alkynylphosphane Ligands
iv) and the tolyl derivative 3 needed 6 h in toluene heated markable absorption is one ν(CϵC) band in the range
under reflux conditions to give the binuclear 4 together with 2160–2164 cm–1, which is typical of P-coordinated
free phosphane. However, once complex 1 was isolated, its PPh2CϵCR ligands.
conversion to the binuclear derivative 2 was not complete
(even in toluene at reflux) and mixture of 2/1/ PPh2CϵCR)2 of complexes 2, 4 and 6 is consistent with
PPh2CϵCPh was always present. In fact, monitoring the their analytical and spectroscopic data and it has been con-
The bimetallic formulation with the double-bridged (μ-
a
reaction between pure binuclear derivative
2
and firmed by an X-ray diffraction study on complex 4. The
PPh2CϵCPh (4 equiv.) in THF by 31P{1H} NMR spec- MALDI-TOF(+) mass spectra exhibit the corresponding
troscopy in CDCl3 established that a mixture of 2/1/ molecular peak and those due to the fragment
PPh2CϵCPh was always observed, thereby indicating a [Pt2(PPh2CϵCR)3]+. The IR spectra of 2, 4 and 6 confirm
possible equilibrium in solution.
the presence of bridging and terminal alkynylphosphane li-
We note that the formation of η2-alkyne bimetallic com- gands. Thus, they exhibit one high-frequency absorption
plexes was irreversible (4, 6) or clearly a majority (2), thus (2167–2178 cm–1) located at slightly higher frequencies than
indicating that the Pt0 centre has a remarkable preference those of mononuclear derivatives 1, 3, 5 (2160–2164 cm–1),
for the π-donor acetylenic density of P-bonded alkynyl- which is assigned to the terminal P-coordinated
phosphanes. This behaviour is in agreement with previous PPh2CϵCR, and a low-frequency band (1717–1756 cm–1),
results in binuclear PtII–Pt0 systems that contain μ- which appears with a shoulder, attributed to the alkynyl-
κP:η2PPh2CϵCR bridging ligands, in which the PtII centre phosphane bridging group. The remarkable lowering of this
has been shown to have a clear preference for P coordina- latter νCϵC frequency in relation to free phosphanes is
tion,[44] whereas the alkyne PCϵCR unit favours coordina- consistent with that expected for an η2-coordination to the
tion to the relatively electron-rich Pt0 centre. In the context Pt0 centre.[44,52,53] The most relevant feature of the 1H
of this work, we note that related [{M(μ-κP:η2- NMR spectra is the presence of two different methyl signals
PPh2CϵCCF3)L}2] (M = Pt, Pd; L = PPh2CϵCCF3, PPh3) in the tolyl derivative 4. All binuclear complexes (2, 4 and 6)
derivatives were isolated by Carty et al. in 1974 from the display in the 31P{1H} NMR spectra the expected AAЈXXЈ
reduction of cis-[MCl2(PPh2CϵCCF3)2] with NaBH4 in splitting pattern with the corresponding 195Pt satellites.
THF and the structure of [{Pd(μ-κP:η2-PPh2CϵCCF3)- From the analysis of the spectra obtained (two pseudotrip-
PPh3}2] was confirmed by X-ray diffraction.[49]
Attempts to carry out a complete X-ray diffraction study it is only possible to obtain the value of the N parameter [N
lets located at δ = –5.78 to –7.22 and at 4.06 to 8.10 ppm),
2
3
of the mononuclear complexes 1, 3 or 5 were unsuccessful. = J(PA,PXcis) + J(PA,PXЈtrans) = 79.3–79.6 Hz]. It is worth
The poor quality of all crystals obtained prevented their noting that both signals appear remarkably downfield-
satisfactory refinement. However, the connectivity was une- shifted with regard to that of the corresponding precursors
quivocally established on a crystal of 5, thereby confirming 1, 3 and 5, thus suggesting the occurrence of more robust
the presence of four alkynylphosphanes coordinated to the Pt–P bonds in the tricoordinate platinum units. In each
Pt0 centre. Evidence of the tetrahedral coordination of four complex the most deshielded signal (δ = 4.06 to 8.10 ppm),
alkynylphosphanes in solution is mainly derived from their with 1J(PA,Pt) coupling constants in the range 3764–
195Pt{1H} NMR spectra, which show a quintet due to cou- 3834 Hz, is tentatively attributed to the alkynylphosphane
pling to four phosphorus (δ = –4601 to –4606 ppm), with a bridging ligands, whereas the low-frequency resonance [δ =
1
coupling constant 1J(Pt,P) of 3942 to 3956 Hz (Figure 1) in –7.22 to –5.78 ppm; J(PX,Pt) = 3523–3643 Hz] is assigned
the typical range of Pt0 phosphane complexes[51] and the to the terminal P-coordinated alkynylphosphanes. This as-
31P{1H} NMR spectra, which exhibit a singlet resonance (δ signment is in agreement with previous observations in het-
= –17.7 to –18.6 ppm) flanked by platinum satellites. The erobridged d8–PtII [d8 = PtII, PdII][3,4,8,10] and d6–PtII [d6 =
downfield shift in relation to the PPh2CϵCR free ligands RhIII, IrIII, RuII][11,12] and mixed-valence PtII–Pt0 com-
[Δδ = 14.8 (1), 14.5 (3), 15.7 ppm (5)] confirms the P coordi- plexes[7,44] that contain terminal and bridging alkynylphos-
nation to the Pt0 centre. The MALDI-TOF(+) mass spectra phane ligands in which the phosphorus resonance of the
show the peaks that correspond to [Pt(PPh2CϵCR)3]+ frag- bridging ligands is systematically found notably deshielded
ments as parent peaks and in the IR spectra the most re- in relation to the terminal one. The 195Pt{1H} NMR spectra
Figure 1. 195Pt{1H} NMR spectrum of [Pt(PPh2CϵCTol)4] (3) in CDCl3 at 298 K.
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J. R. Berenguer, E. Lalinde, M. T. Moreno, P. Montaño
FULL PAPER
show the expected platinum resonance as a well-resolved Table 1. Selected distances [Å] and angles [°] of 4.
dddd centred in the range δ = –4614 to –4590 ppm, which
Pt1–C10
Pt1–C11
Pt1–P3
Pt1–P1
Pt2–C1
Pt2–C2
Pt2–P4
Pt2–P2
2.039(6)
2.068(7)
2.2447(16)
2.272(2)
2.026(6)
2.068(7)
2.2472(16)
2.278(2)
P1–C1
1.778(7)
1.767(7)
1.784(8)
1.785(8)
1.305(9)
1.290(9)
1.187(10)
1.181(10)
is very close to the resonance found for the mononuclear
precursors. The analysis of these signals as first-order spin
systems allowed us to obtain the long range two- and four-
bond platinum–phosphorus coupling constants [2J(Pt,PAЈ)
P2–C10
P3–C19
P4–C28
C1–C2
C10–C11
C19–C20
C28–C29
4
= 56–75 Hz; J(Pt,PXЈ) = 24–26 Hz].
The structure of 4 is shown in Figure 2 and relevant
bond lengths and angles are summarized in Table 1. The
structure consists of two “Pt(PPh2CϵCTol)” moieties con-
nected by two alkynylphosphane ligands (Pt···Pt 4.267 Å),
which are coordinated by acting as μ-κP:η2 bridging li-
gands. The central octanuclear Pt2P2C4 core is bent, with
the dihedral angle formed by the best platinum coordina-
C11–Pt1–P3
C10–Pt1–P1
C11–Pt1–P1
P3–Pt1–P1
C2–Pt2–P4
C1–Pt2–P2
C2–Pt2–P2
114.5(2)
102.0(2)
138.1(2)
107.37(6)
116.9(2)
102.1(2)
139.0(2)
103.94(7)
109.6(2)
110.2(2)
C19–P3–Pt1
C28–P4–Pt2
C2–C1–P1
121.1(2)
119.6(3)
152.2(6)
142.2(6)
152.9(6)
144.5(7)
179.3(7)
179.3(9)
178.4(7)
176.6(8)
C1–C2–C3
C11–C10–P2
C10–C11–C12
C20–C19–P3
C19–C20–C21
C29–C28–P4
C28–C29–C30
tion planes being 57.91°. The geometry around the Pt P4–Pt2–P2
C1–P1–Pt1
C10–P2–Pt2
centres is approximately trigonal planar, which is typical of
metal(d10)–alkyne complexes.[18,44,53–55] The dihedral angles
between the planes P1–Pt1–P3 and C10–Pt1–C11 is 9.7(4)°
and between P2–Pt2–P4 and C1–Pt2–C2 is 5.6(4)°. The tor-
sion angles P1–C1–C2–C3 and P2–C10–C11–C12 are 7.97 than the uncoordinated alkynyl lengths [1.187(10),
and 0.66°, respectively. 1.181(10) Å] and comparable to those found in the mixed-
The η2-platinum(0)–acetylenic linkage is asymmetric valence PtII–Pt0 complexes [Pt(C6F5)2(tht)(μ-PPh2CϵCR)-
with the Pt–Cα distances [2.026(6), 2.039(6) Å] being Pt(PPh3)2] [R = Ph[44] 1.302(5) Å; R = C6H4–CϵCPh,[7]
slightly shorter than the corresponding Pt–Cβ bond lengths 1.303(7) Å]. The bridging P–Cα–Cβ–Cγ skeleton shows a
[2.068(7) Å]. As expected, the η2-complexed CϵC bond marked deviation from linearity [P–Cα–Cβ 152.2(6),
lengths [1.305(9) and 1.290(9) Å] are considerably longer 152.9(6)°; Cα–Cβ–Cγ 142.2(6), 144.5(7)°] relative to the
Figure 2. Molecular structure of [{Pt(PPh2CϵCTol)(μ-κP:η2-PPh2CϵCTol)}2] (4).
4
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Pt0 Complexes with Alkynylphosphane Ligands
angles at Cα and Cβ observed on the terminal P–Cα–Cβ– standing in solution, evolves, even at low temperature, to-
Cγ units [P–Cα–Cβ 178.4(7), 179.3(7)°; Cα–Cβ–Cγ 176.6(8), ward the oxidized product [Pt2{PPh2CϵCP(O)Ph2}2(μ-
179.3(9)°]. Both facts are consistent with a remarkable κ2PPЈ-PPh2CϵCPPh2)3] (8). In fact, attempts to crystallize
backbonding from Pt0 centres into the π* orbitals of the complex 7 at –30 °C in THF/n-hexane afforded crystals
bridging ligands, thereby affording some metallacycloprop- of 8.
ene character to the bonding. The Pt–P bridging bond
The crystal structure of complex 8 is shown in Figure 3,
lengths [2.272(2), 2.278(2) Å] are slightly longer than the with selected bond lengths and angles in Table 2. The struc-
corresponding Pt–P terminal bond lengths [2.2447(16), ture consists of two bis(diphenylphosphanyl)acetylene oxide
2.2472(16) Å]. However, the P–C(acetylenic) distances are platinum fragments “[Pt{PPh2CϵCP(O)Ph2}]” bridged by
almost identical [1.778(7), 1.767(7) Å (bridging); 1.784(8), three dppa ligands. The platinum(0) centres show a dis-
1.785(8) Å (terminal)].
torted tetrahedral environment with P–Pt–P in the central
In this context, we decided to examine the reactivity of bridging core that lies in the range 99.91(4)–109.22(4)° and
[Pt2(dba)3] toward the potentially trifunctional ligand P(7)/(9)–Pt–P(dppa) in the range 111.76(3)–118.95(3)°. The
bis(diphenylphosphanyl)acetylene, PPh2CϵCPPh2 (dppa). Pt–P–Cacetylene(dppa) angles deviate slightly from the ideal
It is worth mentioning that zerovalent platinum–dppa de- tetrahedral [112.39(13)–114.01(13)°]. The three dppa brid-
rivatives have been investigated in the past. Thus, King et al. ges display P–CϵC angles that range from 175.0 to
reported that the reaction of K2[PtCl4] with PPh2CϵCPPh2 177.3(4)°, whereas in the terminal dppa oxide these angles
(excess amount) in EtOH/H2O under reflux conditions in
the presence of NaBH4 gave
a
yellow solid of
[Pt(PPh2CϵCPPh2)2],[48] for which a mononuclear formula-
tion with a linear κ-P two-coordination was proposed on
the basis of IR spectroscopy. A binuclear platinum(0) com-
plex [{Pt(PPh3)2(PPh2CϵCPPh2)}2] with a typical tetrahe-
Table 2. Selected distances [Å] and angles [°] of 8·1.5THF.
Pt1–P7
Pt1–P3
2.2643(10)
2.2940(9)
C1–C2
C3–C4
C5–C6
C7–C8
C9–C10
P8–O1
P10–O2
1.201(6)
1.201(5)
1.213(6)
1.205(6)
1.207(6)
1.370(6)
1.418(5)
dral Pt0 environment and P coordination for the dppa li- Pt1–P1
2.3034(10)
2.3073(10)
2.2731(10)
2.3065(10)
2.3178(10)
2.3180(11)
gand has also been reported,[50] but it was only charac-
Pt1–P5
Pt2–P9
terized by spectroscopic means (IR, 1H NMR and UV/Vis).
Pt2–P4
Following a procedure similar to that used for binuclear
Pt2–P6
complexes 2, 4 and 6, treatment of [Pt2(dba)3] with
PPh2CϵCPPh2 (1:4) (Scheme 1, v) in THF resulted in the
formation of a yellow solid (7), the IR spectra of which
exhibit a band at 2007 cm–1 close the band at 2002 cm–1
that was reported by King for [Pt(dppa)2], thereby suggest-
ing that both complexes are the same. This complex 7 was
formulated as the binuclear neutral derivative
[Pt2(PPh2CϵCPPh2)2(μ-κ2PPЈ-PPh2CϵCPPh2)3], in which
two “Pt(PPh2CϵCPPh2)” fragments are attached through
Pt2–P2
P7–Pt1–P3
P7–Pt1–P1
P3–Pt1–P1
P7–Pt1–P5
P3–Pt1–P5
P1–Pt1–P5
P9–Pt2–P4
P9–Pt2–P6
P4–Pt2–P6
P9–Pt2–P2
P4–Pt2–P2
P6–Pt2–P2
C1–P1–Pt1
C2–P2–Pt2
C3–P3–Pt1
C4–P4–Pt2
112.08(2)
117.11(2)
104.32(3)
113.69(3)
107.28(3)
101.24(3)
111.74(3)
118.93(3)
103.63(4)
112.39(3)
109.22(4)
99.91(4)
C5–P5–Pt1
C6–P6–Pt2
C2–C1–P1
C1–C2–P2
C4–C3–P3
C3–C4–P4
C6–C5–P5
C5–C6–P6
C8–C7–P7
C7–C8–P8
C10–C9–P9
113.14(13)
114.01(13)
177.0(4)
176.0(4)
176.9(4)
177.3(4)
175.0(4)
176.1(4)
171.9(4)
170.1(5)
174.6(4)
a
system of three dppa bridging ligands (μ-κ2PPЈ-
PPh2CϵCPPh2). This formulation, mainly based on spec-
troscopic (mass spectrometry and NMR) data, is in accord-
ance with the typical tetrahedral coordination of Pt0 and
with its easy evolution into the related complex 8. Com-
pound 7 is moderately stable in the solid state, but upon
C9–C10–P10 177.8(5)
112.39(13)
113.87(14)
113.86(13)
113.08(13)
C7–P7–Pt1
O1–P8–C8
C9–P9–Pt2
117.17(14)
114.6(3)
117.06(14)
O2–P10–C10 116.7(2)
Figure 3. Molecular structure of [Pt2{PPh2CϵCP(O)Ph2}2(μ-κ2PPЈ-PPh2CϵCPPh2)3]·1.5THF (8·1.5THF).
Eur. J. Inorg. Chem. 0000, 0–0
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J. R. Berenguer, E. Lalinde, M. T. Moreno, P. Montaño
FULL PAPER
range from 170.1(5) to 177.8(5)°. The CϵC bond lengths analysis of which as a first-order spin system allows us to
[1.201(5)–1.213(6) Å] are similar to the uncoordinated CϵC calculate not only the 1J(Pt,PX) (3692 Hz), but also
distance in 4. The P–O [1.370(6), 1.418(5) Å] bond lengths 1J(Pt,PA) (4594 Hz) and 4J(Pt,Pfree) (30 Hz) that are not re-
and the O–P–C angles [114.6(3), 117.17(14)°] are in the solved in the corresponding phosphorus spectrum. As ex-
range of those observed in terminal alkynylphosphane ox- pected, in the 31P{1H} NMR spectrum of 8, the oxidized
ides.[8,18,56]
phosphorus resonance appears notably deshielded in rela-
The helical twist for the Pt2(dppa)3 skeleton about the tion to that in complex 7 (δ = 6.6 ppm for 8 versus δ =
Pt···Pt axis is 27.5°, taken as the average of the torsion –31.6 ppm for 7), whereas the signals that correspond to PA
angles P5–Pt1–Pt2–P6 28.9°, P1–Pt1–Pt2–P2 30.1° and P3– and PX atoms are slightly affected [PA, δ = –7.52 ppm (q);
2
Pt1–Pt2–P4 23.6°. We note that the related tris(dppa) d10 PX, δ = –21.23 ppm (d); J(PA,PX) = 65 Hz].
derivatives, [Ni2(CO)2(dppa)3],[57] [Cu2(dppa)3(CH3CN)2]-
Although unexpected, the formation of an alkynylphos-
[BF4]2,[58] [Cu2(dppa)3(O3SCF3)2],[58] [Cu2(X)2(dppa)3] (X = phane oxide complex starting from the corresponding alk-
TeBu, SSiMe3),[59,60] [Ag2(dppa)3(BF4)2],[61] [Au2(dppa)3- ynylphosphane ligand has been previously reported. Of
Cl2][62]; and d6 derivatives, [Mo2(CO)6(dppa)3][63] and interest for this work are, for example, [{(η5-C5H5)-
[W2(CO)6(dppa)3],[64] are also helical. This arrangement Ni}2{PPh2(O)CϵCCF3}], which was obtained as one by-
leaves the terminal diphenylphosphane acetylene oxide frag- product in the reaction of [(η5-C5H5)2Ni] with
ments in a transoidal disposition, with a torsion angle be- PPh2CϵCCF3;[56] [Pt{η2-PPh2(O)CϵCMe}(dcpe)] [dcpe =
tween the two terminal acetylene vectors C9–C10 and C8– 1,2-bis(dicyclohexylphosphino)ethane], which was obtained
C7 of 51.23°.
by air oxidation of [Pt(η2-PPh2CϵCMe)(dcpe)];[18] or
The IR spectrum of 7 exhibits a characteristic ν(CϵC) [(C6F5)2Pt{μ-κO:η2-PPh2(O)CϵCPh}]2,[8] which was ob-
medium absorption at 2107 cm–1, whereas 8 also displays a tained as a subproduct in the reaction between [Ir(cod)-
ν(CϵC) signal at similar frequencies (2109 cm–1), together (PPh2CϵCPh)2](ClO4) [cod = 1,5-cyclooctadiene] and [cis-
with a new band in the P=O stretching region (1211 cm–1), Pt(C6F5)2(thf)2].
in accordance with the presence of the partially oxidized
bis(diphenylphosphane)acetylene PPh2CϵCP(O)Ph2 li- binuclear derivatives, stabilized by a double alkynylphos-
gands. The 31P{1H} NMR spectrum of 7 (Figure 4) displays phane bridging system, [{Pt(PPh2CϵCR)(μ-κP:η2-
In conclusion, we have shown that the formation of the
a first-order AX3 pattern (δA = –7.6 ppm, δX = –21.4 ppm, PPh2CϵCR)}2] [R = Ph (2), Tol (4), C5H4N-2 (6)] with tri-
JAX = 64 Hz) with well-resolved platinum satellites for the gonal planar Pt0 centres, takes place through the formation
bridging P–(dppa) signal [J(Pt,PX) = 3692 Hz], attributed of the tetrahedral mononuclear derivatives [Pt(PPh2-
to the coordinated phosphorus atoms and a high-field sing- CϵCR)4] [R = Ph (1), Tol (3), C5H4N-2 (5)]. It is also pos-
let (δ = –31.6 ppm), which appears close to that seen in free sible to generate binuclear derivatives 7 and 8, in which two
dppa, due to the uncoordinated phosphorus of terminal PtL [L = PPh2CϵCPPh2 or PPh2CϵCP(O)Ph2] apical frag-
dppa. The 195Pt{1H} NMR spectrum of 7 shows a doublet ments are bridged by three (μ-κ2PPЈ-PPh2CϵCPPh2) bridg-
of quartet of small doublets centred at δ = –4471 ppm, the ing ligands to form a helical twisted cage.
Figure 4. 31P{1H} NMR spectra of 7.
6
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Pt0 Complexes with Alkynylphosphane Ligands
4.74. IR: ν = ν(CϵC) 2164 (m) cm–1. MALDI-TOF(+): m/z (%)
˜
Experimental Section
1
= 1096 [Pt(PPh2CϵCTol)3]+ (100). H NMR (400.1 MHz, CDCl3,
General Remarks: All reactions were carried out under an Ar atmo-
sphere using Schlenk tube techniques. Solvents were obtained with
a solvent purification system (M-BRAUN MB SPS-800). IR spec-
tra were recorded with a FTIR Nicolet Nexus spectrometer as Nu-
jol mulls between polyethylene sheets and NMR spectra were re-
corded with either a Bruker ARX 300 or a Bruker Avance 400
spectrometer. Chemical shifts are reported in ppm relative to exter-
nal standards (SiMe4, 85% H3PO4 and Na2[PtCl6]) and coupling
constants in Hz. Elemental analyses were carried out with a Per-
kin–Elmer 2400 CHNS/O microanalyzer and MALDI-TOF spec-
tra with a Microflex MALDI-TOF Bruker spectrometer operating
in the linear and reflector modes using dithranol as matrix. Starting
materials [Pt2(dba)3],[65] PPh2CϵCPh, PPh2CϵCTol, and
PPh2CϵC-C5H4N-2 were prepared as described previously.[66,67]
PPh2CϵCPPh2 (Aldrich) was used as supplied.
20 °C): δ = 7.40 (m, 16 H, o-Ph), 7.05 [AB system: δA = 7.09, δB
=
6.99, J(A–B) = 8 Hz, 16 H, C6H4], 7.04 [t, J(H–H) = 7 Hz, 8 H, p-
Ph], 6.91 [t, J(H–H) = 7 Hz, 16 H, m-Ph], 2.34 (s, 12 H, C6H4–
CH3) ppm. 31P{1H} NMR (162.0 MHz, CDCl3, 20 °C): δ = –18.6
[s, 1J(Pt,P) = 3957 Hz] ppm. 195Pt{1H} NMR (85.62 MHz, CDCl3,
1
20 °C): δ = –4604 [quintet, J(Pt,P) = 3956 Hz] ppm.
[{Pt(PPh2CϵCTol)(μ-κP:η2-PPh2CϵCTol)}2] (4): Complex 4 was
prepared as a yellow solid (0.123 g, 84% yield) by following a sim-
ilar procedure to that of 2, using [Pt2(dba)3] (0.100 g, 0.092 mmol)
and PPh2CϵCTol (0.109 g, 0.366 mmol) (1:4 molar ratio).
C84H68P4Pt2 (1591.54): calcd. C 63.39, H 4.31; found C 63.56, H
4.51. IR: ν = ν(CϵC)terminal 2168 (m); ν(CϵC)bridge 1743 (sh), 1717
˜
(m) cm–1. MALDI-TOF(+): m/z (%) = 1590 [M – H]+ (29), 1290
[Pt2(PPh2CϵCTol)3]+ (100). 1H NMR (300.1 MHz, CDCl3, 20 °C):
δ = 7.69 (m, 14 H, Ph), 7.42 (m, 6 H, Ph), 7.20 (m, 18 H, Ph),
7.03–6.85 (14 H, Ph), 6.46 [AB system: δA 6.50, δB = 6.41, J(A–B)
= 6 Hz, 4 H, C6H4], 2.31 (s, 6 H, C6H4–CH3), 2.09 (s, 6 H, C6H4–
[Pt(PPh2CϵCPh)4] (1): A purple solution of [Pt2(dba)3] (0.200 g,
0.183 mmol) in THF (30 mL) was treated with PPh2CϵCPh
(0.420 g, 1.467 mmol) (1:8 molar ratio) and the mixture was stirred
to give a yellow solution in 30 min. After 1.5 h of stirring, the solu-
tion was concentrated to approximately 5 mL. Addition of cold
MeOH (10 mL) afforded a yellow solid (0.213 g, 43% yield), which
was collected by filtration and washed with cold MeOH (2 mL).
The 31P{1H} NMR spectrum was assigned to 1, with small traces
of free phosphane (PPh2CϵCPh) and 2. Recrystallization from
THF/n-hexane gave 1 as a pure solid. C80H60P4Pt (1340.34): calcd.
CH3) ppm. 31P{1H} NMR (162.0 MHz, CDCl3, 20 °C): δAAЈ
=
4.06; δXXЈ = –5.78 ppm, N = JAX + JAXЈ = 79.4 Hz, 1J(Pt,PA) =
3834 Hz, 1J(Pt,PX) = 3536 Hz. 195Pt{1H} NMR (85.62 MHz,
CDCl3, 20 °C): δ = –4614 [dddd, 1J(Pt,PA) = 3834 Hz, 1J(Pt,PX)
2
4
3536 Hz, J(Pt,PAЈ) 75 Hz, J(Pt,PXЈ) 26 Hz] ppm.
[Pt(PPh2CϵC–C5H4N-2)4] (5): A purple solution of [Pt2(dba)3]
(0.200 g, 0.183 mmol) in THF (30 mL) was treated with
PPh2CϵC–C5H4N-2 (0.421 g, 1.467 mmol) (1:8 molar ratio). After
2 h of stirring, the yellow solution obtained was evaporated to a
small volume (5 mL) and cold MeOH (10 mL) was added to give
5 as an orange solid (0.245 g, 50% yield). C76H56N4P4Pt (1344.29):
calcd. C 67.90, H 4.20, N 4.17; found C 67.57, H 4.34, N 3.82.
C 71.69, H 4.51; found C 72.06, H 4.31. IR: ν = ν(CϵC) 2160 (m)
˜
cm–1. MALDI-TOF(+): m/z (%) = 1054 [Pt(PPh2CϵCPh)3]+ (100).
1H NMR (400.1 MHz, CDCl3, 20 °C): δ = 7.42 (m, 18 H, Ph), 7.35
(m, 6 H, Ph), 7.18 [d, J(H–H) = 4 Hz, 14 H, Ph], 7.06 [t, J(H–H)
= 8 Hz, 8 H, Ph], 6.92 [t, J(H–H) = 8 Hz, 14 H, Ph] ppm. 31P{1H}
NMR (162.0 MHz, CDCl3, 20 °C): δ = –18.5 [s, 1J(Pt,P) =
3954 Hz] ppm. 195Pt{1H} NMR (85.62 MHz, CDCl3, 20 °C): δ =
IR: ν = ν(CϵC) 2163 (m) cm–1. MALDI-TOF(+): m/z (%) = 1057
˜
[Pt(PPh2CϵC–C5H4N-2)3]+ (100). 1H NMR (400.1 MHz, CDCl3,
20 °C): δ = 8.52 (m, 4 H, H6), 7.46 (m, 18 H), 7.35 (m, 4 H), 7.12
(m, 8 H), 7.02 (m, 8 H), 6.94 [t, J(H–H) = 7.2 Hz, 14 H] (aromatics)
ppm. 31P{1H} NMR (162.0 MHz, CDCl3, 20 °C): δ = –17.7 [s,
1J(Pt,P) = 3942 Hz] ppm. 195Pt{1H} NMR (85.62 MHz, CDCl3,
1
–4606 [quintet, J(Pt,P) = 3954 Hz] ppm.
[{Pt(PPh2CϵCPh)(μ-κP:η2-PPh2CϵCPh)}2] (2): PPh2CϵCPh
(0.100 g, 0.366 mmol) (1:4 molar ratio) was added to a solution
of [Pt2(dba)3] (0.100 g, 0.092 mmol) in THF (30 mL). The initially
purple solution slowly changed to orange (2 h) and then to yellow
after 8 h of stirring. Evaporation to a small volume (5 mL) and the
addition of cold MeOH (10 mL) afforded 2 as a yellow solid
(0.120 g, 85% yield). C80H60P4Pt2 (1535.43): calcd. C 62.58, H 3.94;
1
20 °C): δ = –4601 [quintet, J(Pt,P) = 3943 Hz] ppm.
[{Pt(PPh2CϵC–C5H4N-2)(μ-κP:η2-PPh2CϵC–C5H4N-2)}2]
(6):
Method A: Complex 6 was prepared as a yellow solid (0.070 g,
50% yield) by following a similar procedure to that of 2, using
[Pt2(dba)3] (0.100 g, 0.092 mmol) and PPh2CϵC–C5H4N-2
(0.105 g, 0.366 mmol) (1:4 molar ratio). Method B: A yellow solu-
tion of 5 (0.100 g, 0.074 mmol) in toluene (30 mL) was stirred for
4 d, and a yellow solid was gradually generated. The final product
6 was collected by filtration, washed with toluene (2 mL) and n-
hexane (2 mL) and dried (0.030 g, 41% yield). C76H56N4P4Pt2
(1539.38): calcd. C 59.30, H 3.67, N 3.64; found C 58.81, H 3.67,
found C 62.94, H 4.09. IR: ν = ν(CϵC)terminal 2167 (m);
˜
ν(CϵC)bridge 1741 (m), 1722 (sh) cm–1. MALDI-TOF(+): m/z (%)
1
= 1534 [M – H]+ (38), 1248 [Pt2(PPh2CϵCPh)3]+ (100). H NMR
(300.1 MHz, CDCl3, 20 °C): δ = 7.67 (m, 10 H, Ph), 7.42 (m, 6 H,
Ph), 7.35 (m, 2 H, Ph), 7.19 (m, 20 H, Ph), 7.03 (m, 6 H, Ph), 6.85
(m, 8 H, Ph), 6.71 [t, J(H–H) = 7 Hz, 4 H, Ph], 6.56 [d, J(H–H) =
7 Hz, 4 H, Ph] ppm. 31P{1H} NMR (121.5 MHz, CDCl3, 20 °C):
δAAЈ = 4.11; δXXЈ = –6.25 ppm; N = JAX + JAXЈ = 79.3 Hz,
1J(Pt,PA) = 3814 Hz, 1J(Pt,PX) = 3523 Hz. 195Pt{1H} NMR
(85.62 MHz, CDCl3, 20 °C): δ = –4609 [dddd, 1J(Pt,PA) = 3814 Hz,
N 3.62. IR: ν = ν(CϵC)
2178 (m); ν(CϵC)bridge 1756 (sh),
˜
terminal
1717 (m) cm–1. MALDI-TOF(+): m/z (%) = 1538 [M – H]+ (100),
1251 [Pt2(PPh2CϵC–C5H4N-2)3]+ (71). 1H NMR (300.1 MHz,
CDCl3, 20 °C): δ = 8.50 (m, 2 H, H6 ), 8.24 (m, 2 H, H6μ), 7.87 (m,
t
2
4
1J(Pt,PX) = 3523 Hz, J(Pt,PAЈ) = 71 Hz, J(Pt,PXЈ) = 24 Hz] ppm.
8 H), 7.35 (m, 10 H), 7.16 (m, 4 H), 6.82 (m, 12 H) (aromatics),
6.45 [d, J(H–H) = 7.6 Hz, 2 H, H3] ppm. 31P{1H} NMR
(121.5 MHz, CDCl3, 20 °C): δAAЈ = 8.10, δXXЈ = –7.22 ppm; N =
JAX + JAXЈ 79.6, 1J(Pt,PA) = 3764 Hz, 1J(Pt,PX) = 3643 Hz.
195Pt{1H} NMR (85.62 MHz, CDCl3, 20 °C): δ = – 4590 [dddd,
1J(Pt,PA) = 3764 Hz, 1J(Pt,PX) = 3643 Hz, 2J(Pt,PAЈ) = 56 Hz,
4J(Pt,PXЈ) = 24 Hz] ppm.
[Pt(PPh2CϵCTol)4] (3): A purple solution of [Pt2(dba)3] (0.200 g,
0.183 mmol) in THF (30 mL) was treated with PPh2CϵCTol
(0.440 g, 1.467 mmol) (1:8 molar ratio), and the mixture was stirred
for 2 h. The resulting yellow solution was evaporated to a small
volume (5 mL). Addition of cold MeOH (10 mL) caused the sepa-
ration of a yellow solid (0.238 g, 47% yield), which was shown to
be 3, with small traces of free phosphane (PPh2CϵCTol) and 4.
Recrystallization from THF/n-hexane gave 3 as a pure solid.
[Pt2(PPh2CϵCPPh2)2(μ-κ2PPЈ–PPh2CϵCPPh2)3] (7): A purple
solution of [Pt2(dba)3] (0.100 g, 0.095 mmol) in THF (30 mL) was
C84H68P4Pt (1396.45): calcd. C 72.25, H 4.91; found C 71.65, H treated with PPh2CϵCPPh2 (0.144 g, 0.366 mmol) and the mixture
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J. R. Berenguer, E. Lalinde, M. T. Moreno, P. Montaño
FULL PAPER
stirred for 2 h. The resulting yellow solution was evaporated to a diffusion at –30 °C of n-hexane into a solution of 4 in CH2Cl2,
small volume (5 mL). Addition of cold MeOH (10 mL) gave 7 as whereas yellow crystals of 8 were obtained by slow diffusion at
a yellow solid (0.150 g, 69% yield). C130H100P10Pt2 (2362.14): calcd. –30 °C of n-hexane into a solution of complex 7 in THF, and 1.5
C 66.10, H 4.27; found C 66.12, H 4.23. IR: ν = ν(CϵC) 2107 (m) molecules of THF were found in the asymmetric unit of 8. X-ray
˜
cm–1. MALDI-TOF(+): m/z (%) = 1572 [Pt2(PPh2CϵCPPh2)3]+ intensity data were collected with graphite-monochromated Mo-Kα
(100), 1967 [Pt2(PPh2CϵCPPh2)4]+ (40). 1H NMR (300.1 MHz, radiation. Data collection was performed with a Nonius κCCD
CDCl3, 20 °C): δ = 7.55 (pt, 8 H, Ph), 7.24 (m, 8 H, Ph), 7.17 (m, area-detector diffractometer, and the images were processed with
32 H, Ph), 7.07 (m, 4 H, Ph), 7.00 (m, 12 H, Ph), 6.92 (m, 12 H, the DENZO and SCALEPACK suite of programs.[68] The absorp-
Ph), 6.72 (m, 24 H, Ph) ppm. 31P{1H} NMR (121.5 MHz, CDCl3, tion corrections were carried out using multiscan[69] with the
2
20 °C): = AX3 system δPA = –7.6 [q, J(PA,PX) = 64 Hz, 1 P], δPX WINGX program suite.[70] The structures were solved by Patterson
2
1
–21.4 [d, J(PX,PA) = 64 Hz, J(Pt,PX) = 3692 Hz, 3 P], –31.6 (s, 1 Methods using SHELXS-97[71] (4) or direct and Patterson methods
P) ppm. 195Pt{1H} NMR (85.62 MHz, CDCl3, 20 °C): δ = –4471 using SIR2004[72] (8), and refined by full-matrix least-squares cycles
[dqd, 1J(Pt,PA) = 4594 Hz, 1J(Pt,PX) = 3692 Hz, 4J(Pt,Pfree) = on F2 with SHELXL-97.[71] All non-hydrogen atoms were assigned
30 Hz] ppm.
anisotropic displacement parameters. All the hydrogen atoms were
constrained to idealized geometries by fixing isotropic displace-
ment parameters to 1.2 times the Uiso value of their attached car-
bon atom for the aromatic and 1.5 times for the methyl groups. For
complex 4, inspection of the structure with PLATON[73] showed
the possibility of the presence of symmetry planes, therbey suggest-
ing three new possible space groups (P21am, Pma2, Pmam). All
attempts to resolve the structure in any of them were unsuccessful.
Several restraints have been used to model the THF molecules in
8. Finally, the structures show some residual peaks greater than
1 eA–3 in the vicinity of the platinum atoms (4) or the crystalli-
zation solvent (8), but with no chemical meaning.
Crystals of [Pt2{PPh2CϵCP(O)Ph2}2(μ-κ2PPЈ–PPh2CϵCPPh2)3]
(8): Yellow crystals of 8 were grown by slow diffusion of n-hexane
into
a
concentrated solution of
7 in THF at –30 °C.
C
130H100O2P10Pt2 (2394.14): calcd. C 65.22, H 4.21; found C 64.85,
H 4.22. IR: ν = ν(CϵC) 2108 (m); ν(P=O) 1211 (s) cm–1. MALDI-
˜
TOF(+): m/z (%) = 1572 [Pt2(PPh2CϵCPPh2)3]+ (100), 1983
[Pt2(PPh2CϵCPPh2)3{PPh2CϵCP(O)Ph2}]+ (50). 1H NMR
(300.1 MHz, CDCl3, 20 °C): δ = 7.63 (m, 8 H, Ph), 7.42 (m, 4 H,
Ph), 7.14 (m, 40 H, Ph), 7.00 (m, 12 H, Ph), 6.92 (m, 8 H, Ph), 6.72
(m, 28 H, Ph) ppm. 31P{1H} NMR (121.5 MHz, CDCl3, 20 °C): δ
= 6.56 (s, 1 P), AX3 system δPA = –7.52 [q, J(PA,PX) = 65 Hz, 1
2
P], δPX = –21.23 [d, J(PA,PX) = 65 Hz, J(Pt,PX) = 3673 Hz, 3 P]
2
1
CCDC-871278 (for 4) and -871279 (for 8·1.5THF) contain the sup-
plementary crystallographic data for this paper. These data can be
ppm.
X-ray Crystallography: Table 3 reports details of the structural obtained free of charge from The Cambridge Crystallographic
analysis of 4 and 8. Pale yellow crystals of 4 were obtained by slow Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Table 3. Crystallographic data for 4 and 8·1.5THF.
4
8·1.5THF
Empirical formula
Mr
T [K]
C84H68P4Pt2
1591.44
173(1)
C138.5 H112O7P10Pt2
2588.32
173(1)
λ [Å]
0.71073
orthorhombic
P212121
18.1764(3)
19.1815(3)
19.8367(4)
90
0.71073
monoclinic
P21/n
13.1666(2)
28.5794(5)
32.5787(5)
90
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
90
90
6916.1(2)
4
1.528
4.179
3152
0.2ϫ0.175ϫ0.175
1.52 to 26.37
–22ՅhՅ16
–17ՅkՅ23
–16ՅlՅ24
25803
99.4900(10)
90
12091.4(3)
4
1.374
2.496
γ [°]
V [Å3]
Z
Dcalcd. [Mgm–3]
ε [mm–1]
F(000)
5048
Crystal size [mm3]
2θ range [°]
Index ranges
0.40ϫ0.25ϫ0.20
2.67 to 26.37
–16ՅhՅ16
–35ՅkՅ35
–40ՅlՅ40
162035
Reflections collected
Independent reflections
Data / restraints / parameters
Goodness of fit on F2[a]
Final R indices [IϾ2σ(I)][a]
R indices (all data)
13645 [R(int) = 0.0447]
13645 / 0/811
1.017
R1 = 0.0397, wR2 = 0.0694
R1 = 0.0660, wR2 = 0.0783
1.031 and –0.873
24615 [R(int) = 0.0765]
24615 / 12 / 1384
1.044
R1 = 0.0339, wR2 = 0.0909
R1 = 0.0441, wR2 = 0.0975
1.784 and –0.856
Largest diff. peak and hole [eÅ–3]
[a] R1 = Σ(|Fo| – |Fc|)/Σ|Fo|; wR2 = [Σw(F2o – Fc2)2/ΣwF2o]1/2; goodness of fit = {Σ[w(F2o – Fc2)2]/(Nobsd. – Nparam.)}1/2; w = [σ2(F2o) + (g1P)2
+ g2P]–1; P = [max(F2o;0) + 2F2c]/3.
8
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Eur. J. Inorg. Chem. 0000, 0–0

Job/Unit: I20265
/KAP1
Date: 26-06-12 17:43:11
Pages: 11
Pt0 Complexes with Alkynylphosphane Ligands
[32]
[33]
A. García, J. Gómez, E. Lalinde, M. T. Moreno, Organometal-
lics 2006, 25, 3926–3934.
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J. R. Berenguer, E. Lalinde, M. T. Moreno, P. Montaño
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Date: 26-06-12 17:43:11
Pages: 11
Pt0 Complexes with Alkynylphosphane Ligands
Alkynylphosphane Ligands
Tetrahedral Pt0 complexes [Pt(PPh2CϵCR)4],
which evolve into binuclear derivatives
[{Pt(PPh2CϵCR)(μ-κP:η2-PPh2CϵCR)}2]
[R = Ph, tolyl, C5H4N-2], and binuclear
J. R. Berenguer, E. Lalinde,*
M. T. Moreno,* P. Montaño ........... 1–11
Platinum(0) Complexes with Alkynylphos-
phane Ligands
compounds stabilized by
a
(μ-PPh2-
CϵCPPh2)3 triply bridging system have
been prepared and fully characterized.
Keywords: Platinum / Bridging ligands /
Phosphane ligands / Homometallic com-
plexes / Alkynes
Eur. J. Inorg. Chem. 0000, 0–0
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11