Oxidatively induced P-O bond formation through reductive coupling between phosphido and acetylacetonate, 8-hydroxyquinolinate, and picolinate groups

Article abstract of DOI:10.1021/ic4004005

The dinuclear anionic complexes [NBu₄][(R_F) ₂M^II(μ-PPh₂)₂M′ ^II(N^∥O)] (R_F = C₆F₅. N^∥O = 8-hydroxyquinolinate, hq; M = M′ = Pt 1; Pd 2; M = Pt, M′ = Pd, 3. N^∥O = o-picolinate, pic; M = Pt, M′ = Pt, 4; Pd, 5) are synthesized from the tetranuclear [NBu₄] ₂[{(R_F)₂Pt(μ-PPh₂) ₂M(μ-Cl)}₂] by the elimination of the bridging Cl as AgCl in acetone, and coordination of the corresponding N,O-donor ligand (1, 4, and 5) or connecting the fragments cis-[(R_F) ₂M(μ-PPh₂)₂]^2- and M′(N^∥O) (2 and 3). The electrochemical oxidation of the anionic complexes 1-5 occurring under HRMS(+) conditions gave the cations [(R_F)₂M(μ-PPh₂) ₂M′(N^∥O)]⁺, presumably endowed with a M(III),M′(III) core. The oxidative addition of I₂ to the 8-hydroxyquinolinate complexes 1-3 triggers a reductive coupling between a PPh₂ bridging ligand and the N,O-donor chelate ligand with formation of a P-O bond and ends up in complexes of platinum(II) or palladium(II) of formula [(R_F)₂M^II(μ-I)(μ-PPh ₂)M′^II(P,N-PPh₂hq)], M = M′ = Pt 7, Pd 8; M = Pt, M′ = Pd, 9. Complexes 7-9 show a new Ph₂P- OC₉H₆N (Ph₂P-hq) ligand bonded to the metal center in a P,N-chelate mode. Analogously, the addition of I₂ to solutions of the o-picolinate complexes 4 and 5 causes the reductive coupling between a PPh₂ bridging ligand and the starting N,O-donor chelate ligand with formation of a P-O bond, forming Ph₂P-OC ₆H₄NO (Ph₂P-pic). In these cases, the isolated derivatives [NBu₄][(Ph₂P-pic)(R_F)Pt ^II(μ-I)(μ-PPh₂)M^II(R_F)I] (M = Pt 10, Pd 11) are anionic, as a consequence of the coordination of the resulting new phosphane ligand (Ph₂P-pic) as monodentate P-donor, and a terminal iodo group to the M atom. The oxidative addition of I₂ to [NBu₄][(R_F)₂Pt^II(μ-PPh ₂)₂Pt^II(acac)] (6) (acac = acetylacetonate) also results in a reductive coupling between the diphenylphosphanido and the acetylacetonate ligand with formation of a P-O bond and synthesis of the complex [NBu₄][(R_F)₂Pt^II(μ-I)(μ- PPh₂)Pt^II(Ph₂P-acac)I] (12). The transformations of the starting complexes into the products containing the P-O ligands passes through mixed valence M(II),M′(IV) intermediates which were detected, for M = M′ = Pt, by spectroscopic and spectrometric measurements.

Full text of DOI:10.1021/ic4004005

Article
pubs.acs.org/IC
Oxidatively Induced P−O Bond Formation through Reductive
Coupling between Phosphido and Acetylacetonate,
8‑Hydroxyquinolinate, and Picolinate Groups†
Andersson Arias, Juan Fornies, Consuelo Fortuno,* and Antonio Martín
́
̃
Departamento de Química Inorgan
E-50009 Zaragoza, Spain
́ ́ ́
ica, Instituto de Síntesis Química y Catalisis Homogenea, Universidad de Zaragoza-C.S.I.C.,
Piero Mastrorilli,* Stefano Todisco, Mario Latronico, and Vito Gallo
Dipartimento DICATECh del Politecnico di Bari and Istituto CNR-ICCOM, Via Orabona 4, I-70125 Bari, Italy
S
* Supporting Information
ABSTRACT: The dinuclear anionic complexes [NBu4]-
[(RF)2MII(μ-PPh2)2M′II(N∧O)] (RF = C6F5. N∧O = 8-hydrox-
yquinolinate, hq; M = M′ = Pt 1; Pd 2; M = Pt, M′ = Pd, 3. N∧O =
o-picolinate, pic; M = Pt, M′ = Pt, 4; Pd, 5) are synthesized from
the tetranuclear [NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-Cl)}2] by the
elimination of the bridging Cl as AgCl in acetone, and coordination
of the corresponding N,O-donor ligand (1, 4, and 5) or connecting
the fragments “cis-[(RF)2M(μ-PPh2)2]2−” and “M′(N∧O)” (2 and
3). The electrochemical oxidation of the anionic complexes 1−5
occurring under HRMS(+) conditions gave the cations [(RF)2M-
(μ-PPh2)2M′(N∧O)]+, presumably endowed with a M(III),M′(III)
core. The oxidative addition of I2 to the 8-hydroxyquinolinate complexes 1−3 triggers a reductive coupling between a PPh2
bridging ligand and the N,O-donor chelate ligand with formation of a P−O bond and ends up in complexes of platinum(II) or
palladium(II) of formula [(RF)2MII(μ-I)(μ-PPh2)M′II(P,N-PPh2hq)], M = M′ = Pt 7, Pd 8; M = Pt, M′ = Pd, 9. Complexes 7−9
show a new Ph2P-OC9H6N (Ph2P-hq) ligand bonded to the metal center in a P,N-chelate mode. Analogously, the addition of I2
to solutions of the o-picolinate complexes 4 and 5 causes the reductive coupling between a PPh2 bridging ligand and the starting
N,O-donor chelate ligand with formation of a P−O bond, forming Ph2P-OC6H4NO (Ph2P-pic). In these cases, the isolated
derivatives [NBu4][(Ph2P-pic)(RF)PtII(μ-I)(μ-PPh2)MII(RF)I] (M = Pt 10, Pd 11) are anionic, as a consequence of the
coordination of the resulting new phosphane ligand (Ph2P-pic) as monodentate P-donor, and a terminal iodo group to the M
atom. The oxidative addition of I2 to [NBu4][(RF)2PtII(μ-PPh2)2PtII(acac)] (6) (acac = acetylacetonate) also results in a
reductive coupling between the diphenylphosphanido and the acetylacetonate ligand with formation of a P−O bond and
synthesis of the complex [NBu4][(RF)2PtII(μ-I)(μ-PPh2)PtII(Ph2P-acac)I] (12). The transformations of the starting complexes
into the products containing the P−O ligands passes through mixed valence M(II),M′(IV) intermediates which were detected,
for M = M′ = Pt, by spectroscopic and spectrometric measurements.
that the oxidation of dinuclear derivatives can afford M(III),M-
(III) or M(II),M(IV) complexes.19−32
INTRODUCTION
■
Although the chemistry of platinum and palladium is usually
studied in tandem and complexes in high oxidation states (III
and IV) have been well recognized for platinum, the chemistry
of palladium in oxidation states higher than (II) has been
investigated in detail in the last 10 years.2−10 These oxidized
species easily undergo reductive elimination and play a key role
as intermediates in some synthetic design.11−18 The M(II)/
M(IV) cycles can achieve transformations that are hardly
accessible otherwise. The usual access to the M(IV) complexes
is the oxidation of M(II) derivatives, and it is well established
In our current research on phosphanido derivatives, we have
reported three types of palladium or platinum(II) dinuclear
complexes [(RF)2M(μ-PPh2)2M′L2]n− (RF = C6F5, M, M′ = Pt,
Pd; L = RF, n = 2, A; 2L = benzoquinolinate (C∧N), n = 1, B; L
= NCCH3, n = 0, C). The two RF groups bonded to a metal
center in these complexes can act as terminal blocking ligands
as well as provide adittional structural information (19F NMR).
The oxidation of these types of compounds with I2 (Chart 1)
has been reported.33−35 In all cases, the oxidized intermediate
†Polynuclear Homo- or Heterometallic Palladium(II)−Platin-
um(II) Pentafluorophenyl Complexes Containing Bridging
Diphenylphosphido Ligands. 31. For part 30, see ref 1.
Received: February 18, 2013
Published: April 18, 2013
© 2013 American Chemical Society
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Chart 1
Chart 2
Scheme 1
complexes evolve through a reductive coupling with formation
of a P−C bond and new palladium(II) and platinum(II)
derivatives. For complexes of type A (Chart 1), the reductive
coupling between PPh2 and C6F5 groups and formation of
complexes containing the PPh2C6F5 ligand was observed.33
Only the platinum intermediate M(III),M(III) derivative,
[(RF)2PtIII(μ-PPh2)2PtIII(RF)2](Pt−Pt), was stable enough,
isolated and characterized.33,36 For complexes of type B, the
oxidation in the case of the Pt(II),Pt(II) derivative results in the
formation of the diplatinum Pt(II),Pt(IV) [NBu4][(RF)2PtII(μ-
PPh2)2PtIV(C∧N)I2]34 (B-ox) complex which was stable
enough and could be isolated and fully characterized. However,
for the Pd(II),Pd(II) or the mixed Pt(II),Pd(II) complexes, the
intermediates M(II),M(IV) could neither be isolated nor
observed in solution, and the M(II),M(II) complexes
containing the aminophosphane Ph2P-bzq (P−C coupling,
see Chart 2) were obtained. Finally, the formation of Ph2PC6F5
was observed for the neutral complexes type C through the
isolated and characterized intermediates of palladium or
platinum(III) [(RF)2PtIII(μ-PPh2)2MIIII2](Pt-M) (M = Pt,
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a
Table 1. 31P and 195Pt NMR Data of 1−5 and 7−12 in Deuteroacetone at 298 K
2
1
1
1
1
δPA
δPB
JP ,P
JP ,Pt
JP ,Pt
JP ,Pt
JP ,Pt
δPt1
δPt2
A
B
A
1
A
2
B
1
B
2
complex
b
1
−137.2
−100.4
−119.0
−139.1
−121.2
−19.9
55.4
−140.4
−106.0
−124.5
−141.6
−125.6
86.0
157
263
216
160
220
1892
2436
1876
2441
−3903
−3450
2
3
1739
1900
1766
1903
1719
1903
1737
49
−3901
−3911
−3905
−4250
c
4
2420
2373
2532
5025
−3542
−4420
5
d
7
8
9
122.9
119.3
80.6
32
37
50.1
1928
2005
2042
1654
2030
119
−4317
−4045
−4050
−4436
−4020
e
10
−71.3
−76.4
−45.8
−88.5
2215
2320
5179
5019
5088
5216
−3572
−3520
10-hydr
11
67.2
13
8
84.6
f
12
81.6
21
2291
29
−3500
a
b
c
d
e
2
f
2
2
2
2
δ in ppm, J in Hz. JPt1,Pt2 = 289 Hz. JPt1,Pt2 = 284 Hz. JPt1,Pt2 = 1220 Hz. JPt1,Pt2 = 1280 Hz. JPt1,Pt2 = 1283 Hz.
Pd).35 The analysis of the results indicated that (i) the
reductive coupling is usually preferred on a palladium rather
than on a platinum center; (ii) the coupling between PPh2 and
benzoquinolinate groups are preferred to the coupling between
PPh2 and C6F5 groups; (iii) in the iodo derivatives, the coupling
between PPh2 and I to form iodophosphane has not yet been
observed.
In this paper we report on the synthesis of new dinuclear
anionic phosphanido derivatives of platinum and palladium(II)
containing 8-hydroxyquinolinate or o-picolinate as ligands, and
the reaction of the complexes [NBu4][(RF)2Pt(μ-PPh2)2MII(L-
L′)] [M = Pt, Pd; L-L′ = 8-hydroxyquinolinate (hq), o-
picolinate (pic) or acetylacetonate (acac)] with I2.
palladium or platinum halido complexes are reacted with
bidentate chelating ligands.35,38−43 The IR spectra of complexes
1−5 in the solid state confirmed the presence of the ligands in
the respective complexes. These were characterized by
elemental analysis, high resolution mass spectrometry, and
NMR spectroscopy. The 19F NMR spectra of the complexes
were recorded in deuteroacetone, and the relevant data are
collected in Experimental Section. In these complexes, the two
pentafluorophenyl groups are inequivalent, but the chemical
environments of the two rings are very similar and some 19F
nuclei were almost isochronous. The 31P{1H} NMR spectra are
more informative. In all cases, the two inequivalent P atoms
appear at high fields (in the range −100 to −145 ppm) as
expected for a “M(μ-PPh2)2M” (M = Pt, Pd) fragment without
a metal−metal bond.44−46 As previously noted,47 the
phosphanido 31P NMR signals appear at lower field when Pd
atoms were present in the molecule. The assignment of the
proper signal to each of the phosphanido P atoms (Table 1)
RESULTS AND DISCUSSION
Synthesis of [NBu4][(RF)2M(μ-PPh2)2M′(N∧O)] (RF
■
=
C6F5. N∧O = 8-hydroxyquinolinate (hq), M = M′ = Pt,
1; Pd, 2; M = Pt, M′ = Pd, 3) and [NBu4][(RF)2Pt(μ-
PPh2)2M(N∧O)] (RF = C6F5. N∧O = picolinate (pic), M = Pt
4; Pd, 5). The synthesis of the asymmetric complexes 1, 4, and
5 (Scheme 1a) was carried out by elimination of the bridging
chloro ligands as AgCl from the corresponding tetranuclear
derivatives [NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-Cl)}2],37 and
treatment of the resulting species with the corresponding
N∧O-donor ligand. Complexes 2 and 3 were obtained by
reacting the anion cis-[Pt(RF)2(PPh2)2]2−37 with the binuclear
[{Pd(μ-Cl)(N∧O)}2] complexes. The anionic moiety behaves
as a diphosphane ligand and produces the displacement of the
bridging chloro ligand in the binuclear derivative (Scheme 1b).
This type of displacement is rather frequent when dinuclear
1
was made on the basis of the H−31P HMQC and 1H NOESY
spectra. In fact, once assigned the ortho protons of the phenyl
rings bonded to the P atoms by means of the 1H−31P HMQC,
the position of the PPh2 group was established thanks to the
NOE contact between the ortho protons of the phenyls and the
N−C-H protons of the N∧O ligand. The attribution of the
coupling constants between P and Pt was made by comparison
of 31P{1H} and 195Pt{1H} spectra. The 195Pt{1H} spectra of 1,
3, 4, 5 showed broad multiplets at ca. δ −3900 for the Pt1
atoms bonded to the pentafluorophenyl rings. For 1 and 4, the
195Pt{1H} spectra showed also sharp signals at δ −3450 (1) or δ
−3542 (4) for the Pt2 atom bonded to the N∧O ligand (Table
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Figure 1. HRMS(+) spectrogram of 1 in MeCN showing the peak corresponding to the cation [(RF)2Pt(μ-PPh2)2Pt(hq)]+. The error between
calculated and observed isotopic patterns is 5.3 ppm.
Scheme 2
1). The geminal coupling constants between the two Pt atoms
in these complexes were 289 and 284 Hz, respectively. The full
the electrospray ionization source can act as an electrochemical
cell capable to assist redox processes,48,49 we tested the
possibility to oxidize electrochemically the anionic complexes
1−5 by submitting them to HRMS(+) analysis in positive
mode. In the conditions detailed in the Experimental Section,
the five monoanions were smoothly oxidized and the
HRMS(+) spectrograms showed intense peaks ascribable to
1
assignment of all H NMR signals was made by means of 1D
1
and 2D H NMR spectra and is reported in the Experimental
Section.
The HRMS(−) analysis of the anionic complexes 1−5
showed the peaks corresponding to their formulas. Given that
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the corresponding monocationic complexes deriving from loss
of two electrons. This suggests that an electrochemical
oxidation of 1−5 occurs to give probably the corresponding
M(III),M′(III) species of the general formula [(RF)2MIII(μ-
PPh2)2M′III(L2)]+(Pt−Pt) (L2 = N∧O). Figure 1 shows the
HRMS(+) spectrogram of 1, which could be due to the cation
[(RF)2PtIII(μ-PPh2)2PtIII(hq)]+(Pt−Pt).50 The tendency of 1−
5 to undergo an electrochemical oxidation was found less
marked in the case of the mixed metal Pt−Pd complexes 3 and
5, with respect to 1, 2, and 4, as indicated by the relative
intensities of the ion currents due to the oxidized species.51
Reaction of [NBu4][(RF)2M(μ-PPh2)2M′(L-L′)] with I2.
The addition of I2 to CH2Cl2 solutions of complexes
[NBu4][(RF)2M(μ-PPh2)2M′(L-L′)] (L-L′ = hq, 1−3; pic, 4,
5; acac, 639) in a 1:1 molar ratio afforded complexes 7−12 with
structures depending on the L-L′ ligand and/or the metal cores
(Scheme 2). All products 7−12 have a common core
constituted by a M-P-M′-I four-membered ring and a
coordinated Ph2P-hq, Ph2P-pic, or Ph2P-acac ligand (see
Chart 2), which are the result of the PPh2/L-L′ coupling
with P−O bond formation (Scheme 2). Complexes 7−12 are
nonplanar binuclear derivatives endowed with large M···M (M
= Pt, Pd) distances as expected for 32 VEC saturated
complexes. As we will comment below, the formation of
these ligands is the consequence of a reductive coupling
induced by I2 oxidation. The ligand Ph2P-hq is coordinated to
the metal centers in 7−9 as chelating, while Ph2P-pic and Ph2P-
acac act as monodentate (κ-P) in complexes 10−12, and the
binuclear anion contains also a terminal iodide ligand. Complex
10 was very sensitive to moisture and in solution of wet
solvents quantitatively hydrolyses to give 10-hydr (Scheme 2).
In addition, the reaction which produces complex 11 is more
complicated since migration of one C6F5 group from Pt to Pd
occurred.
Figure 3. View of the molecular structure of the complex
[(C6F5)2Pt(μ-I)(μ-PPh2)Pd(P,N-Ph2P-hq)] Me2CO·0.25n-C6H14
(9·Me2CO·0.25n-C6H14). Solvent molecules are omitted for clarity.
The HRMS(+) spectrograms of the neutral products 7−9
showed intense peaks due to [M + Na]+ adducts, while
HRMS(−) analysis of 10−12 (for which the complexes are
anionic) showed peaks due to [M]−.
The molecular structures of 7, 9, 11, and 12 were established
by X-ray diffraction studies. Figures 234−5 show molecular
drawings of complexes 7 and 9 and of the anionic parts of
complexes 11 and 12, while Tables 234−5 list the most
Figure 4. View of the molecular structure of the anion of the complex
[NBu4][(Ph2P-pic)(C6F5)Pt(μ-I)(μ-PPh2)Pd(C6F5)I] CH2Cl2
(11·CH2Cl2). Solvent molecules are omitted for clarity.
Figure 5. View of the molecular structure of the anion of the complex
[NBu4][(C6F5)2Pt(μ-I)(μ-PPh2)PtI(Ph2P-acac)] (12).
relevant bond distances and angles for the respective
complexes. The crystal structures confirm the dinuclear nature
of the complexes. In all cases, the core contains the “Pt(μ-
Figure 2. View of the molecular structure of the complex
[(C6F5)2Pt(μ-I)(μ-PPh2)Pt(P,N-Ph2P-hq)] 2Me2CO (7·2Me2CO).
Solvent molecules are omitted for clarity.
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Table 2. Selected Bond Lengths (Å) and Angles (°) for [(C6F5)2Pt(μ-I)(μ-PPh2)Pt(P,N-PPh2hq)]·2Me2CO (7·2Me2CO)
Pt(1)−C(7)
Pt(1)−I
Pt(2)−P(1)
2.005(3)
2.6743(2)
2.2673(7)
Pt(1)−C(1)
Pt(2)−N
Pt(2)−I
2.077(3)
2.149(2)
Pt(1)−P(1)
Pt(2)−P(2)
P(2)−O(1)
2.2853(7)
2.1763(7)
1.627(2)
2.6971(2)
C(7)−Pt(1)−C(1)
90.62(11)
C(7)−Pt(1)−P(1)
C(7)−Pt(1)−I
P(1)−Pt(1)−I
N−Pt(2)−P(1)
N−Pt(2)−I
94.48(8)
C(1)−Pt(1)−P(1)
C(1)−Pt(1)−I
N−Pt(2)−P(2)
P(2)−Pt(2)−P(1)
P(2)−Pt(2)−I
174.77(9)
93.29(8)
86.07(7)
102.48(3)
167.74(2)
75.979(6)
169.61(8)
81.862(19)
166.75(7)
92.06(6)
P(1)−Pt(2)−I
Pt(2)−P(1)−Pt(1)
81.675(19)
93.14(3)
Pt(1)−I−Pt(2)
Table 3. Selected Bond Lengths (Å) and Angles (°) for [(C6F5)2Pt(μ-I)(μ-PPh2)Pd(P,N-PPh2hq)]·Me2CO·0.25n-C6H14
(9·Me2CO·0.25n-C6H14)
Pt−C(7)
Pt−I
Pd−P(2)
P(2)−O(1)
2.013(3)
2.6788(2)
2.2015(8)
1.640(2)
Pt−C(1)
Pt−Pd
Pd−P(1)
2.080(3)
3.1421(3)
2.2641(8)
Pt−P(1)
Pd−N
Pd−I
2.2790(9)
2.175(3)
2.7464(3)
C(7)−Pt−C(1)
88.84(13)
C(7)−Pt−P(1)
C(7)−Pt−I
P(1)−Pt−I
C(1)−Pt−Pd
I−Pt−Pd
N−Pd−P(1)
N−Pd−I
P(1)−Pd−I
P(2)−Pd−Pt
I−Pd−Pt
92.56(10)
177.87(10)
85.34(2)
C(1)−Pt−P(1)
C(1)−Pt−I
C(7)−Pt−Pd
P(1)−Pt−Pd
N−Pd−P(2)
P(2)−Pd−P(1)
P(2)−Pd−I
N−Pd−Pt
178.19(9)
93.25(9)
122.49(10)
46.05(2)
132.15(9)
55.619(6)
165.31(8)
92.90(7)
84.49(7)
102.57(3)
162.74(2)
121.07(7)
46.44(2)
84.04(2)
141.04(2)
53.608(6)
87.52(3)
P(1)−Pd−Pt
Pt−I−Pd
70.773(7)
Pd−P(1)−Pt
Table 4. Selected Bond Lengths (Å) and Angles (°) for [NBu4][(PPh2-pic)(C6F5)Pt(μ-I)(μ-PPh2)Pd(C6F5)I]·CH2Cl2
(11·CH2Cl2)
Pt−C(1)
Pt−I(1)
Pd−I(2)
2.059(4)
2.6855(2)
2.6807(3)
Pt−P(2)
Pd−C(7)
Pd−I(1)
2.2074(8)
Pt−P(1)
Pd−P(1)
P(2)−O(1)
2.3292(9)
2.2629(8)
1.660(3)
2.024(4)
2.6919(3)
C(1)−Pt−P(2)
94.29(10)
C(1)−Pt−P(1)
C(1)−Pt−I(1)
P(1)−Pt−I(1)
C(7)−Pd−I(2)
C(7)−Pd−I(1)
I(2)−Pd−I(1)
Pd−P(1)−Pt
165.62(10)
86.85(9)
P(2)−Pt−P(1)
P(2)−Pt−I(1)
C(7)−Pd−P(1)
P(1)−Pd−I(2)
P(1)−Pd−I(1)
Pt−I(1)−Pd
99.60(3)
177.76(2)
92.83(10)
176.05(3)
80.40(2)
79.39(2)
90.29(10)
172.20(11)
96.315(10)
96.91(3)
79.463(8)
Table 5. Selected Bond Lengths (Å) and Angles (°) for [NBu4][(C6F5)2Pt(μ-I)(μ-PPh2)PtI(PPh2-acac)] (12)
Pt(1)−C(1)
Pt(1)−I(1)
Pt(2)−I(1)
2.018(7)
2.653(1)
2.674(1)
Pt(1)−C(7)
Pt(2)−P(1)
Pt(2)−I(2)
2.078(7)
Pt(1)−P(1)
Pt(2)−P(2)
P(2)−O(1)
2.308(2)
2.198(2)
1.621(5)
2.300(2)
2.688(1)
C((1)−Pt((1)−C(7)
88.2(3)
C((1)−Pt((1)−P(1)
C(1)−Pt((1)−I((1)
P(1)−Pt(1)−I(1)
P(2)−Pt(2)−I(1)
P2)−Pt(2)−I(2)
I(1)−Pt(2)−I(2)
Pt(2)−P(1)−Pt((1)
95.26(19)
176.44(17)
81.98(5)
C(7)−Pt((1)−P(1)
C(7)−Pt(1)−I(1)
P(2)−Pt(2)−P(1)
P(1)−Pt(2)−I(1)
P(1)−Pt(2)−I(2)
Pt(1)−I(1)−Pt(2)
175.93(18)
94.68(18)
100.18(7)
81.64(5)
173.31(5)
89.53(5)
169.51(4)
85.06(4)
89.17(3)
102.85(7)
PPh2)(μ-I)M” fragment, being M = Pt for 7 and 12, and M =
Pd for 9 and 11. The intermetallic distances (3.306(1) Å for 7,
3.142(1) Å for 9, 3.437(1) Å for 11, and 3.601(2) Å for 12) are
in agreement with the absence of a M−M bond, as expected for
these saturated (32 VEC) complexes. The metal atoms lie in
the center of square planes, each plane sharing an edge. The
core formed by the two metals and the two bridging atoms is
not planar, and the value of the dihedral angle formed by the
coordination planes is 53.08(2)° for 7, 57.52(2)° for 9,
50.77(2)° for 11, and 31.93(3)° for 12. All these structural
parameters, along the variability found in the values of the Pt−
I−M and Pt−P−M angles, are in agreement with the well-
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known flexibility of the “Pt(μ-PPh2)(μ-I)M” central frag-
ment.33,35,42,52−54
δ(μ-31P). All complexes collected in Table 6 contain the “M(μ-
I)(μ-PPh2)M” fragment, and it is apparent that the increase of
value of δ(μ-31P) is related to a larger value of α.
In complexes 7, 9 (neutral), and 12 (anionic) the two
pentafluorophenyl ligands retain the mutually cis disposition to
a Pt atom. The other metal atom, Pt(2) in 7, Pd in 9, and Pt(2)
in 12, completes its coordination sphere with the formed Ph2P-
hq ligand which is coordinated in a P,N-chelate mode
(complexes 7 and 9), while in complex 12, the Ph2P-acac
ligand formed in the course of the reaction acts as a
monodentate P-donor ligand and the iodide which is present
in the mixture completes the coordination environment of
Pt(2). Within the acac fragment the sequence of distances
C(26)−C(27) 1.337(9), C(27)−C(28) 1.470(9), C(26)−
O(1) 1.362(7), and C(28)−O(2) 1.212(8) is different from
those of a typical acac ligand,42,55 as is to be expected according
to its rather different bonding situation of this moiety (Chart
2). Finally, in complex 11, one of the pentafluorophenyl groups
has migrated from the Pt to the Pd atom, and the Pt center
completes the coordination environment with the P atom of
the formed phosphane Ph2P-pic while an iodo ligand completes
the coordination sphere of the Pd.
The 19F NMR spectra of 7−12 in deuteroacetone solution
show in all cases two signals due to the o-F atoms (2:2 intensity
ratio), two signals due to the m-F atoms (2:2 intensity ratio),
and two signals due to the p-F atoms (1:1 intensity ratio). This
pattern is in agreement with the presence of two inequivalent
C6F5 groups and indicates that the two halves within each C6F5
ring become equivalent in solution. Moreover, o- and m-F
atoms of the RF rings in trans position with respect to P show
additional 19F−31P couplings. All data are collected in the
1
Experimental Section. The H NMR (1D and 2D) spectra of
7−12 show the signals due to the N∧O ligands, phenyl groups
+
and the possible counterion (NBu4 ) in the proper intensity
ratio. The spectra confirm the stoichiometry of the complexes.
The signals due to the N∧O-groups in complexes 1−5 and
those due to the OR part of the phosphinito ligand PPh2OR in
7−12 deserve some attention. The signal due to H2 (see Table
1 for atom numbering) in N∧O-chelate shifts significantly
downfield when passing from the starting complexes 1−5 to
the products 7−11. The formation of the P−O bond causes
Spectroscopic Properties. The 31P{1H} NMR spectra of
7−12 in deuteroacetone solution show the signal due to the P
atom of the new phosphinito ligand (Ph2P-hq, Ph2P-pic, Ph2P-
acac) at low field (see Table 1), in the 80.6−122.9 δ range. It is
well established that in complexes without a metal−metal bond
the signal due to the P atom of phosphanido ligand involved in
a “M(μ-X)(μ-PPh2)M” fragment (X = halide) appears at lower
field than the signals due to the “M(μ-PPh2)2M” frag-
ment.53,54,56,57 The phosphanido ligands in complexes 7−12,
containing a “M(μ-I)(μ-PPh2)M” fragment, appears at lower
fields (55.4 to −88.5 ppm) than the starting material, −100.4 to
−139.1 ppm. The relationship between δ(μ-P) values and the
M-(μ-P)-M angle in bridging phosphanido complexes has long
been known.47 In addition, in complexes 7, 9, 11, and 12 the
four atoms M, M′, (μ-I) and (μ-P) are not coplanar in the solid
state, and the deviation from the planarity of these four atoms
could be related with the dihedral angle α formed by the two
planes (μ-P), M, (μ-I) and (μ-P), M′, (μ-I). Noteworthy, in 7−
12 the δ(μ-31P) range is wide and the δ(μ-31P) values can be
related with the structural disposition of the four M, (μ-I), (μ-
P), M atoms, i.e., with the planarity of the “M(μ-I)(μ-P)M′”
fragment. Table 6 collects data of this α angle for 7, 9, 11, and
12, as well as for complexes [(RF)2M(μ-I)(μ-PPh2)M′(P,N-
Ph2P-bzq)] (M, M′ = Pt, 13a, M = Pt, M′ = Pd, 13b, M, M′ =
Pd, 13c) reported previously,34 along with the values of their
1
broadening of the H signals which experience a (small) P−H
1
1
coupling, as confirmed by H−31P HMQC and H{31P} NMR
1
experiments. The H NMR spectrum of 12 in deuteroacetone
solution shows two signals for the two inequivalent CH3 groups
and a signal, a doublet (4JP,H = 2 Hz), for the CH proton of the
1
acac group. The H−31P HMQC of 12 showed cross peaks
between the phosphinito P and both the CC−CH3 and the
CH protons.
The 195Pt{1H} spectra of 7 and 9−12 showed broad
multiplets in the −4020 to −4436 ppm range for the Pt1
atoms. For 7, 10, and 12 the 195Pt{1H} spectra showed also
sharp signals at δ −4420 (7), δ −3572 (10), δ −3500 (12) for
the Pt2 atom (Table 1). The geminal coupling constants
between the two Pt atoms in these complexes ranged from
1220 to 1283 Hz, values four times higher than those of the
respective starting complexes (289 Hz for 1 and 284 Hz for 4).
This effect is presumably due to the substitution of a μ-PPh2 by
a μ-I on passing from reagents to products.
Reductive Coupling Between PPh2 and hq, pic, or
acac. Considering our previous experience,33−35,42,54,58 the
synthesis of the bimetallic complexes 7−12 could, in all
likelihood, be the result of an initial oxidation of the
diphosphanido dinuclear complexes 1−5 by means of I2 in
dichloromethane at room temperature, followed by a reductive
coupling between one of the bridging PPh2 and the
corresponding O-donor chelate ligand. The addition of I2
could give either a M(II),M(IV) complex or a binuclear
M(III)-M(III) derivative (Chart 1), which would evolve
through a P−O reductive coupling to the corresponding
Pt(II),Pt(II) final phosphinito complex. In order to gain
insights into the mechanism of formation of 7−12 and to
discriminate between a M(II),M(IV) and a M(III)-M(III)
intermediate (Chart 1), we monitored the reaction between 1
and I2 in conditions that hopefully could guarantee the
detection of the intermediate. Thus, knowing that for the
analogous benzoquinolinate phosphanido M(II),M′(IV) com-
plexes the reductive coupling leading to P∧C bond formation
was hampered in acetone with the diplatinum species, allowing
the isolation of the Pt(II),Pt(IV) intermediate,34 and given that
such Pt(II),Pt(IV) intermediate was quite stable even in
dichloromethane in the presence of an excess of iodide, we
Table 6. δ(μ-P) Values (ppm) and Dihedral Angle α (°) in
complexes with the fragment “M(μ-P)(μ-I)M′”
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monitored the reactions of 1, 4, and 6 with I2 in acetone-d6 at
268 K, in the presence of 4 equiv of NBu4I. In these conditions,
3 equiv of iodine were necessary to convert 1 into a new species
1-ox (>90%), the spectroscopic and spectrometric features of
which indicated as the Pt(II),Pt(IV) intermediate depicted in
Scheme 3. HRMS-MS/MS and 195Pt NMR data were
iodide and the nitrogen of the hq ligand in the plane containing
the two Pt and the two P atoms; the other I and the hq oxygen
in the apical positions. Such a structure is analogous to that of
B-ox, the intermediate formed by addition of I2 to the
benzoquinolinate complex B (Chart 1),34 with the oxygen in
place of carbon in the coordination sphere of Pt2, and for which
the XRD structure is known.
Scheme 3. Proposed Pathway for the 1 to 7 Transformation
The stability of 1-ox in acetone in the presence of iodide
suggests that the mechanism of 1 to 7 transformation (Scheme
3) can be similar to that proposed in our previous work,34
where a P−C bond formation through reductive coupling
between bridging phosphanido and benzoquinolinate groups
occurred.60
Monitoring in a NMR tube the reaction between 1 and I2 in
acetone-d6 (in the absence of NBu4I and with a 1:1 I2:1 molar
ratio) at 298 K revealed that, immediately after the mixing of
the reactants, the mixture contained mainly 1-ox (plus traces of
1 and 7) and that, after 48 h, 1-ox transformed into 7 in ca.
61% spectroscopic yields. The 31P{1H} spectrum of the mixture
after 48 h showed also signals ascribable to two species: the
tetranuclear Pt(II) complex [NBu4]2[{(RF)2Pt(μ-PPh2)2Pt(μ-
I)}2]35 (ca. 15%) and the iododiphenylphosphane complex
NBu4[(RF)2Pt(μ-PPh2)(μ-I)Pt(PPh2I)I] (ca. 21%) featuring
signals at δP 13.4 (2JP,P = 10 Hz; 1JPt,P = 4852 Hz) and δP −63.1
diagnostic for the characterization of 1-ox as the product of
I2 addition to 1 having a square planar Pt(II) atom bridged by
two PPh2 ligands to an octahedral Pt(IV) atom. In fact, 1-ox
showed at the HRMS(−) analysis an intense peak at m/z
1491.8630 with an isotope pattern superimposable to that of
[1+2 I]− (calculated mass = 1491.8712 Da).59 MS/MS analysis
of the peak at m/z 1491.8630 showed fragmentation with loss
of I2, suggesting that the two iodide ligands are in a mutual cis
position. As to the 195Pt{1H} NMR, we have shown that, for
phosphanido complexes, a metal oxidation from +2 to +3
(affording square planar dinuclear species endowed with a
Pt(III)−Pt(III) bond) results in a strong 195Pt shielding,42
whereas metal oxidation from +2 to +4 (affording Pt(II),Pt(IV)
dinuclear species) results in a strong 195Pt deshielding.34
The 195Pt{1H} spectrum of 1-ox showed two signals centered
at δ −2385 and δ −3774 (Table 7). Of this, the first one is a
sharp doublet of doublets (with satellites stemming from the
isotopomer having two 195Pt atoms, 2JPt,Pt = 316 Hz) ascribable
to the Pt atom not bonded to the C6F5 rings (Pt2). The
deshielding of more than 1000 ppm undergone by Pt2 on
passing from 1 (δ −3450) to 1-ox (δ −2835) indicates that Pt2
of 1-ox is an octahedral Pt(IV). The signal at δ −3774 is a
multiplet broadened due to multiple 195Pt−19F couplings and is
ascribed to the Pt(II) atom bonded to the C6F5 rings (Pt1),
which did not change significantly on passing from 1 (δPt1
−3903) to 1-ox.
1
1
(2JP,P = 10 Hz; JPt,P = 1980 Hz, JPt,P = 2194 Hz). This latter
species accounts for the peak at m/z = 1474.7291 (exact mass
for the proposed formula = 1474.7306 Da) found in the
HRMS(−) spectrogram of the reaction mixture. The MS/MS
spectrogram obtained by fragmentation of the m/z =
1474.7291 ion showed only a peak at m/z = 1162.7902
corresponding to the loss of the iododiphenylphosphane.61
Unfortunately, all attempts to isolate 1-ox in the state of purity
were unsuccessful.
The monitoring at 268 K of the reaction of 4 with I2 (3
equiv) in the presence of NBu4I (4 equiv) in acetone-d6
allowed us to detect, immediately after the mixing of reactants,
an intermediate, 4-ox (Scheme 4), having a structure similar to
1-ox. The 31P NMR signals of the Pt(II),Pt(IV) complex 4-ox
were found at δ −99.5 (PA) and δ −77.5 (PB), while the
chemical shift of the octahedral Pt2(IV) was δ −2501 ppm
(Table 7). The HRMS(−) analysis of the solution containing
4-ox showed an intense signal at m/z = 1469.8500
corresponding to [4 + 2 I]− whose fragmentation at the MS/
MS analysis consisted of the loss of I2 with formation of the ion
at m/z = 1216.0178. On standing in acetone-d6 solution at 268
K, 4-ox slowly reacted to give 10 (after 15 h the mixture
contained ca. 35% of 10 and 50% of 4-ox).62
Complex 1-ox was characterized in the 31P NMR by two
mutually coupled signals at δ −107.5 and δ −84.3, (2JP,P = 116
Hz). Perusal of multinuclear NMR data indicates that the
structure of 1-ox was that depicted in Scheme 3, with the
coordination sites of the octahedral Pt2(IV) occupied by a
Interestingly, carrying out the monitoring of 4 plus 1 equiv I2
(without external iodide) in anhydrous thf at 298 K, revealed
Table 7. 31P and 195Pt NMR Data of Intermediates Detected by Monitoring the Reactions of 1, 4, and 6 with I2 in
a
Deuteroacetone at 268 K
2
1
1
1
1
δPA
δPB
JP ,P
JP ,Pt
JP ,Pt
JP ,Pt
JP ,Pt
δPt1
δPt2
A
B
A
1
A
2
B
1
B
2
complex
b
c
c
B-ox
−115.5
−107.5
−99.5
−20.4
−73.4
−88.5
−107.5
−84.3
−77.5
93.1
126
116
119
15
2032
2101
2088
1906
2126
2160
1807
1545
1544
2257
1641
1570
2189
2130
2125
110
1270
1226
1184
4993
1260
−3806
−3774
−3810
nd
−2917
−2385
−2501
nd
d
e
d
e
1-ox
4-ox
g
10*
h
i
6-ox-cis
−81.6
102
2140
−3746
−3746
−2024
−2834
6-ox-trans
a
b
c
d
e
2
g
2
1
2
1
2
1
2
δ in ppm, J in Hz. See Schemes 3−5 for numbering. At 298 K, from ref 34. JPt ,Pt = ca. 100 Hz. JPt ,Pt = 316 Hz. JPt ,Pt = 386 Hz. In thf at 298
h
2
i
2
1
2
1
2
K. JPt ,Pt = 225 Hz. JPt ,Pt = 360 Hz
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Scheme 4. Proposed Pathway for the 4 to 10 Transformation
Scheme 5. Proposed Pathway for the 6 to 12 Transformation
the immediate formation of 4-ox which progressively trans-
formed into an intermediate, 10*, exhibiting 31P{1H} NMR
signals at δP 93.1 (1JPt,P = 4993 Hz) and δP −20.4 (1JPt,P = 2257
Hz, 1JPt,P = 1906 Hz) which, in turn, evolved within 1 h into 10.
The similarity of 31P NMR features between 10* and 7 suggests
that the intermediate 10* might have the structure depicted in
Scheme 4, analogous to 7. The obtainment of 10 as final
product from 10* might therefore be the result of iodide
displacement of the coordinated N on Pt2 (Scheme 4).
Different from the cases of 1 and 4, the NMR monitoring of
the reaction of 6 with 3 equiv of I2 and in the presence of 4
equiv of NBu4I at 268 K showed the transformation of 6 into
two new species in ca. 60:40 molar ratio. The 31P{1H}
spectrum of the reaction mixture showed two mutually coupled
doublets at δ −73.4 (PA) and δ −81.6 (PB), ascribable to a
Pt(II),Pt(IV) species, 6-ox-cis (Scheme 5), analogous to 1-ox
(and 4-ox) along with a singlet at δ −88.5 flanked by two sets
of satellites (JP,Pt = 2160 and 1570 Hz). This signal was
presumably due to a Pt(II),Pt(IV) species (6-ox-trans, Scheme
5) having two iodide ligands in mutual trans position, in order
to justify the symmetry of the molecule evidenced by the NMR
data. Accordingly, the 195Pt{1H} spectrum of the mixture
showed a doublet of doublets at δ −2024 ascribed (by
comparison of the P−Pt coupling constants) to the Pt2(IV) of
6-ox-cis; a triplet at δ −2834 (JP,Pt = 1570 Hz) assigned to the
Pt2(IV) of 6-ox-trans; a broad multiplet at δ −3746 ascribed to
the overlapping of the signals due to the Pt1(II) of 6-ox-cis and
6-ox-trans.
On standing at 268 K, the complex 6-ox-trans quantitatively
transformed into 6-ox-cis,63 which was stable at least for one
week in solution at 268 K, allowing us to detect the HRMS(−)
signal due to the anion of 6-ox at m/z = 1446.8716 (calculated
mass = 1446.8708 Da). The MS/MS study of the ion at m/z =
1446.8716 showed that it fragmented with a loss of I2, giving
the ion at m/z = 1193.0649.
The Pt(II),Pt(IV) complex 6-ox-cis did not evolve to 12
under these conditions (i.e., deuteroacetone solvent and excess
of iodide) even at 298 K. In fact, the 31P{1H} spectrum of the
reaction mixture recorded after 3 days at 298 K showed only
signals of 6-ox-cis along with weak peaks due to (RF)2Pt(μ-
PPh2)(μ-I)Pt(PPh2I)I and other unidentified species. Carrying
out the NMR monitoring of the reaction of 6 with I2 in
acetone-d6 without external iodide and at 298 K revealed the
immediate formation of 6-ox-cis and 6-ox-trans which, within
15 min, rapidly evolved to 12.
With all this information the synthesis of complexes 7−12
could be understood through a similar process observed
earlier34 for the benzoquinolinate derivatives: addition of I2 to
1−6 derivatives gives a dinuclear intermediate with both
diphenylphosphanido groups bridging two metal centers, one
of them in oxidation state II and the other one in oxidation
state IV. The dissociation of a I− group gives an unsaturated
oxidized metal from which the coupling between a bridging
PPh2 and the O-donor ligand forms the new ligand with P−O
bond formation. Taking into account that we have isolated the
Pt(II),Pt(IV) intermediate [NBu4 ][(RF )2 PtI I (μ-
PPh2)2PtIV(C∧N)I2]34 (B-ox) and all attempts to achieve
pure samples of the Pt(II),Pt(IV) intermediates, 1-ox and 4-ox,
were unsuccessful, the processes forming Ph2P-L ligand seem to
be easier for Ph2P-hq, Ph2P-pic, and Ph2P-acac (formation of
P−O bond) than for Ph2P-bzq (formation of P−C bond). It is
to note that the oxidized intermediates have been detected only
for platinum complex, and it is in agreement with the fact that
M(IV)-iodo derivatives are usual for platinum but scarce for
palladium derivatives.13,64−66 The processes described here
imply a M−P and M−O bond cleavage and a P−O bond
formation and result in a formation of PPh2(O∧N) or
PPh2(O∧O) (Chart 2) from a bridging phosphanido complex
and can be considered as an intermediate step for the transition
metal-mediated P−C/O exchange at bound phosphane
ligands.67
Although complexes 7−12 can be isolated as pure solids, the
coupling between the PPh2 group and the O-donor ligand is
not the only process which takes place in the reaction. The
study shows that unidentified species, formed from side
reactions, are present and that the iododiphenylphosphane
complex NBu4[(RF)2Pt(μ-PPh2)(μ-I)Pt(PPh2I)I] and the
tetranuclear derivatives of platinum or palladium(II)
[NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-I)}2],35 which could be the
result of other type of reductive coupling of ligands, are
identified in solution in some of the processes. The
iododiphenylphosphane complex might derive from the P−I
reductive coupling on the M(II),M(IV) intermediates. The
[NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-I)}2] complexes35 show two
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“(RF)2PtII(μ-PPh2)2MII” fragments joined by two I− groups, i.e.,
after addition of I2, the phosphanido groups are still acting as
bridging ligands maintaining the polynuclear fragment and
behaving as a spectator. The evolution of high oxidation state
complexes of palladium and platinum through several paths of
reductive coupling is not surprising, and even on phosphanido
derivatives we observed the formation of a mixture of products
resulting of the P−C and P−P reductive couplings on trinuclear
phosphanido complex.58
Synthesis of [NBu4][(RF)2M(μ-PPh2)2M′(hq)]. M = M′ = Pt, 1.
AgClO4 (0.118 g, 0.570 mmol) was added to a colorless solution of
[NBu4]2[{(RF)2Pt(μ-PPh2)2Pt(μ-Cl)}2] (0.783 g, 0.285 mmol) in
acetone (25 mL). The mixture was stirred in the dark for 1 h. 8-
Hydroxyquinoline (0.083 g, 0.570 mmol) was added and stirred for 30
min. NBu4OH (1 M in methanol, 0.6 mL, 0.6 mmol) was added, and
after 30 min the mixture was filtered through Celite. The yellow
solution was evaporated to ca. 2 mL and i-PrOH (ca. 15 mL) was
added. Complex 1 crystallized as a yellow solid which was filtered,
washed with cold i-PrOH (3 × 1 mL), and dried. Yield: 0.553 g, 65%.
Found: C, 49.59; H, 4.47; N, 1.82. C61H62F10N2OP2Pt2 requires C,
49.46; H, 4.22; N, 1.89. HRMS(−), exact mass for the anion
[C45H26F10NOP2Pt2]−: 1238.0622; measured: m/z: 1238.0623 (M)−.
1H NMR (298 K, (CD3)2CO, 400 MHz): δ 8.33 (d, 1H, H4, 8.4 Hz),
8.12 (broad, 1H, H2), 8.00 (dd, 4H, o-Ph bonded to PA, 10.5 Hz, 7.6
Hz), 7.92 (pseudo t, 4H, o-Ph bonded to PB, 9.1 Hz), 7.41 (pseudo t,
1H, H6, 7.4 Hz), 7.28−7.13 (m, 13 H, overlapped H3, m-Ph, p-Ph),
6.88 (d, 1H, H5, 7.9 Hz), 6.82 (d, 1H, H7, 7.9 Hz), 3.49 (m, 8H,
CONCLUSIONS
■
The bridging phosphanido ligand, in anionic derivatives of
palladium and platinum(II), is not only used as a way for
maintaining the molecular architecture. The transformation of
bridging phosphanido ligands into phosphane is now well
established.33−35,42,54,68−72 The addition of I2 to anionic
phosphanido derivatives of palladium and platinum(II) with
O-donor ligands facilitated the formation of P−O bonds
resulting in the phosphane ligands Ph2P-hq, in complexes 7−9,
Ph2P-pic, in complexes 10 and 11, and Ph2P-acac in complex
12. The process takes place through the intermediate
M(II),M(IV) complexes which evolve to undergo easy
reductive coupling reactions. In no case was observed the
formation of PPh2C6F5 from the starting anionic complexes.
The oxidation of these diphenylphosphanido complexes allows
the identification of intermediates, in some cases stable enough
to be isolated and fully characterized, in formal oxidation states
Pt(III)(square-planar)-Pt(III)(square-planar) or Pt(II)(square-
planar)-Pt(IV)(octahedral). Both type of complexes seem to be
not too different, and in fact the formation of the Pt(II),Pt(IV)
derivatives can be considered as formed by the addition of two
I− ligands to the same metal center of the dinuclear Pt(III)−
Pt(III) compounds. The high oxidation state intermediates
observed in the described reactions could provide opportunities
for achieving distinct and complementary reactivity of the
phosphanido complexes. This reactivity paves the way for the
synthesis of specific ligands through two steps: (a) synthesis of
the adequate starting material by a formal coordination of a
chelate L-L′ ligand (O-donor group) to the “(RF)2PtII(μ-
PPh2)2MII” fragment and (b) oxidation of this new
phosphanido complex which induces the formation of a P−L
bond providing the designed new ligand Ph2P-LL′.
+
+
NBu4+), 1.87 (m, 8H, NBu4 ), 1.49 (pseudo sextet, 8H, 7.4 Hz,
+
NBu4 ), 1.03 (t, 12H, 7.4 Hz, NBu4 ) ppm. 19F NMR (298 K,
3
(CD3)2CO, 376.5 MHz): δ −114.8 (m, 4 o-F, JF,Pt = ca. 330 Hz),
−168.3 (m, 4 m-F), −167.3 (m, 2 p-F).
M = M′ = Pd, 2. n-Butyllitium (2.5 M in hexanes, 0.50 mL, 1.25
mmol) was added to a colorless solution of cis-[Pd(C6F5)2(PPh2H)2]
(0.500 g, 0.615 mmol) in thf (15 mL) under an argon atmosphere at
−78 °C. The yellow solution was stirred for 15 min and [{Pd(μ-Cl)(8-
hq)}2] (0.176 g, 0.308 mmol) was added. The suspension was allowed
to reach room temperature, stirred for 20 h, and evaporated to dryness.
CH2Cl2 (25 mL) was added to the resulting residue, and a solid was
filtered through Celite. The CH2Cl2 solution was evaporated to
dryness, and the residue was dissolved in i-PrOH (ca. 35 mL).
NBu4ClO4 (0.212 g, 0.617 mmol) was added to the solution and 2
started to crystallize. The solution was evaporated to ca. 20 mL and
left in the freezer for 4 h. 2 crystallized as a yellow solid, which was
filtered, washed with cold i-PrOH (3 × 1 mL), and dried, 0.362 g, 45%
yield. Found: C, 56.59; H, 4.73; N, 2.13. C61H62F10N2OP2Pd2 requires
C, 56.19; H, 4.79; N, 2.15. HRMS(−), exact mass for the anion
[C45H26F10NOP2Pd2]−: 1061.9399; measured: m/z: 1061.9428 (M)−.
1H NMR (298 K, (CD3)2CO, 400 MHz): δ 8.20 (d, 1H, H4, 8.3 Hz),
7.99 (dd, 4H, o-Ph bonded to PA, 10.4 Hz, 7.7 Hz), 7.91 (dd, 4H, o-Ph
bonded to PB, 10.1 Hz, 7.8 Hz), 7.63 (broad, 1H, H2), 7.32 (pseudo t,
1H, H6, 8.1 Hz), 7.25 (t, 2H, p-Ph bonded to PB, 6.7 Hz), 7.23 (t, 2H,
p-Ph bonded to PA, 6.7 Hz), 7.18 (t, 4H, m-Ph bonded to PB, 7.4 Hz),
7.12 (t, 4H, m-Ph bonded to PA, 7.2 Hz), 7.07 (dd, 1H, H3, 7.9 Hz, 4.8
Hz), 6.81 (d, 1H, H5, 7.9 Hz), 6.72 (d, 1H, H7, 7.9 Hz), 3.49 (m, 8H,
+
+
NBu4+), 1.87 (m, 8H, NBu4 ), 1.49 (pseudo sextet, 8H, 7.4 Hz,
NBu4 ), 1.03 (t, 12H, 7.4 Hz, NBu4 ) ppm. 19F NMR (298 K,
+
(CD3)2CO, 376.5 MHz): δ −111.5 (m, 2 o-F), −111.7 (2 o-F),
EXPERIMENTAL SECTION
−167.0 (m, 4 m-F), −166.2 (m, 1 p-F), −166.3 (m, 1 p-F).
■
General Comments. C, H, and N analyses were performed with a
Perkin-Elmer 2400 analyzer. IR spectra were recorded on a Perkin-
Elmer Spectrum 100 FT-IR spectrometer. NMR spectra in solution
were recorded on Bruker Avance 400 spectrometers with SiMe4,
CFCl3, 85% H3PO4, and aqueous [PtCl6]2− as external references for
1H, 19F, 31P, and 195Pt, respectively. High resolution mass spectrometry
(HRMS) and MS/MS analyses were performed using a time-of-flight
mass spectrometer equipped with an electrospray ion source (Bruker
micrOTOF-Q II). The analyses were carried out in positive and in
negative ion modes. The samples were introduced as acetonitrile
solutions by continuous infusion with the aid of a syringe pump at a
flow-rate of 180 μL/h. The instrument was operated at end plate offset
−500 V and capillary −4500 V. Nebulizer pressure was 0.3 bar (N2)
and the drying gas (N2) flow 4 L/min. Drying gas temperature was set
at 453 K. The software used for the simulations is Bruker Daltonics
Data Analysis (version 4.0). For all described HRMS peaks, the
isotope patterns were superimposable to those calculated on the basis
of the proposed formulas. Literature methods were used to prepare the
starting materials cis-[M(RF)2(PPh2H)2] (M = Pd, Pt),37
[NBu4]2[{(RF)2Pt(μ-PPh2)2M(μ-Cl)}2] (M = Pd, Pt),37 [{Pd(μ-
Cl)(hq)}2],73 [NBu4][(RF)2Pt(μ-PPh2)2Pt(acac)] (6).39
M = Pt, M′ = Pd, 3. Complex 3 was prepared similarly to 2 from cis-
[Pt(C6F5)2(PPh2H)2] (0.610 g, 0.676 mmol), n-butyllitium (2.5 M in
hexane, 0.54 mL, 1.35 mmol), [{Pd(μ-Cl)(8-hq)}2] (0.193 g, 0.337
mmol) and NBu4ClO4 (0.231 g, 0.676 mmol) as a yellow solid. 0.478
g, 51% yield. Found: C, 52.70; H, 4.43; N, 1.96. C61H62F10N2OP2PdPt
requires C, 52.61; H, 4.49; N, 2.01. HRMS(−), exact mass for the
anion [C45H26F10NOP2PdPt]−: 1150.0005; measured: m/z: 1149.9899
(M)−. 1H NMR (298 K, (CD3)2CO, 400 MHz): δ 8.21 (d, 1H, H4, 8.3
Hz), 8.01 (pseudo t, 4H, o-Ph bonded to PA, 8.8 Hz), 7.92 (dd, 4H, o-
Ph bonded to PB, 9.1 Hz), 7.70 (broad, 1H, H2), 7.32 (pseudo t, 1H,
H6, 8.0 Hz), 7.29−7.08 (m, 13 H, overlapped H3, m-Ph, p-Ph), 6.82
+
(d, 1H, H5, 7.9 Hz), 6.73 (d, 1H, H7, 7.9 Hz), 3.49 (m, 8H, NBu4 ),
+
+
1.87 (m, 8H, NBu4 ), 1.49 (pseudo sextet, 8H, 7.4 Hz, NBu4 ), 1.03
+
(t, 12H, 7.4 Hz, NBu4 ) ppm. 19F NMR (298 K, (CD3)2CO, 376.5
MHz): δ −114.7 (m, 2 o-F, 3JF,Pt = 324 Hz), −115.0 (m, 2 o-F, 3JF,Pt
330 Hz), −168.1 (m, 4 m-F), −167.3 (m, 2 p-F) ppm.
=
Synthesis of [NBu4][(RF)2Pt(μ-PPh2)2M(pic)]. M = Pt, 4.
Complex 4 was prepared similarly to 1 from [NBu4]2[{(RF)2Pt(μ-
PPh2)2Pt(μ-Cl)}2] (0.362 g, 0.132 mmol), AgClO4 (0.055 g, 0.264
mmol), picolinic acid (0.032 g, 0.264 mmol), and NBu4OH (1 M in
methanol, 0.3 mL, 0.300 mmol) as a white solid. Yield: 0.217 g, 57%.
5502
dx.doi.org/10.1021/ic4004005 | Inorg. Chem. 2013, 52, 5493−5506

Inorganic Chemistry
Article
Found: C, 47.34; H, 3.61; N 1.90. C58H60F10N2P2Pt2 requires C,
47.74; H, 4.14; N, 1.92. HRMS(−), exact mass for the anion
[C42H24F10NO2P2Pt2]−: 1216.0415; measured: m/z: 1216.0350 (M)−.
1H NMR (298 K, (CD3)2CO, 400 MHz): δ 8.16 (pseudo td, 1H, H4,
7.5 Hz, 1.3 Hz), 8.08 (d, 1H, H5, 7.5 Hz), 8.02 (d, 1H, H2, 5.0 Hz),
7.90 (pseudo t, 4H, o-Ph bonded to PA, 8.8 Hz), 7.88 (pseudo t, 4H, o-
Ph bonded to PB, 8.8 Hz), 7.47 (dd, 1H, H2, 7.5 Hz, 5.9 Hz), 7.32−
1H, H6, 8.0 Hz), 7.64 (t, 2H, p-Ph bonded to PB, 7.3 Hz), 7.54 (dd,
4H, o-Ph bonded to PB, 12.4 Hz, 8.2 Hz) 7.44 (ddd, 4H, m-Ph bonded
to PB, 8.2 Hz, 7.3 Hz, 3.4 Hz), 7.36−7.29 (m, 6H, p-Ph bonded to PA,
o-Ph bonded to PA), 7.11 (ddd, 4H, m-Ph bonded to PA, 8.0 Hz, 7.5
Hz, 2.2 Hz) ppm. 19F NMR (298 K, (CD3)2CO, 376.5 MHz): δ
−112.6 (m, 2 o-F of the RF trans to P, 3JF,F = 31 Hz), −113.8 (m, 2 o-F
of the RF trans to I, 3JF,F = 24 Hz), −164.2 (t, 1 p-F of the RF trans to
P, 3JF,F = 19 Hz), −165.1 (td, 1 p-F of the RF trans to I, 3JF,F = 19 Hz,
+
7.15 (m, 12 H, m-Ph, p-Ph), 3.49 (m, 8H, NBu4 ), 1.87 (m, 8H,
3
4JF,F = 2 Hz), −165.3 (ddd, 2 m-F of the RF trans to P, JF,F = 31 Hz,
+
+
NBu4+), 1.49 (pseudo sextet, 8H, 7.4 Hz, NBu4 ), 1.03 (t, 12H, 7.4 Hz,
NBu4 ) ppm. 19F NMR (298 K, (CD3)2CO, 376.5 MHz): δ −115.0
(m, 2 o-F, 3JF,Pt = 323 Hz), −115.1 (m, 2 o-F, 3JF,Pt = 325 Hz), −168.0
(m, 4 m-F), −167.2 (m, 2 p-F) ppm.
5
3JF,F = 19 Hz, JF,P = 11 Hz), −165.9 (dd, 1 m-F of the RF trans to I,
3
3JF,F = 24 Hz, JF,F = 19 Hz) ppm.
M = Pt, M′ = Pd, 9. Complex 9 was prepared similarly to 8 from 3
(0.203 g, 0.145 mmol) and I2 (0.037 g, 0.145 mmol) as a orange solid.
0.052 g, 28% yield. Found: C, 42.14; H, 2.24; N, 1.34
C45H26F10INOP2PdPt requires C, 42.32; H, 2.05; N, 1.10. HRMS(+),
M = Pd, 5. Complex 5 was prepared similarly to 1 from
[NBu4]2[{(RF)2Pt(μ-PPh2)2Pd(μ-Cl)}2] (0.200 g, 0.078 mmol),
AgClO4 (0.032 g, 0.156 mmol), picolinic acid (0.019 g, 0.156
mmol), and NBu4OH (1 M in methanol, 0.16 mL, 0.160 mmol) as a
yellow solid 0.135 g, 63% yield. Found: C, 50.72; H, 4.26; N, 2.26.
C58H60F10N2P2Pt2PdPt requires C, 50.83; H, 4.41; N, 2.04.
HRMS(−), exact mass for the anion [C42H24F10NO2P2PtPd]−:
1127.9787; measured: m/z: 1127.9741 (M)−. 1H NMR (298 K,
(CD3)2CO, 400 MHz): δ 8.10 (d, 1H, H5, 7.6 Hz), δ 8.04 (pseudo t,
1H, H4, 7.6 Hz), 7.93 (m, 4H, o-Ph bonded to PA, overlapped), 7.89
(m, 4H, o-Ph bonded to PB, overlapped), 7.64 (d, 1H, H2, 4.1 Hz),
1
measured: m/z: 1299.8893 [M + Na]+, exact mass: 1299.8937; H
NMR (298 K, (CD3)2CO, 400 MHz): δ 10.49 (broad d, 1H, H2, 4.3
Hz), 8.89 (d, 1H, H4, 8.3 Hz), 8.03−7.96 (m, 2H, H3 + H5), 7.82 (d,
1H, H7, 7.3 Hz), 7.75 (pseudo t, 1H, H6, 7.7 Hz), 7.66 (t, 2H, p-Ph
bonded to PB, 7.1 Hz), 7.57−7.43 (m, 8H, o-Ph bonded to PB, m-Ph
bonded to PB), 7.36−7.26 (m, 6H, p-Ph bonded to PA, o-Ph bonded to
PA), 7.11 (pseudo t, 4H, m-Ph bonded to PA, 7.3 Hz) ppm. 19F NMR
(298 K, (CD3)2CO, 376.5 MHz): δ −115.8 (m, 2 o-F of the RF trans
to P, 3JF,Pt = 336 Hz, 3JF,F = 3JF,P = 18 Hz), −117.9 (d, 2 o-F of the RF
+
7.37−7.14 (m, 13 H, m-Ph, p-Ph, H3), 3.49 (m, 8H, NBu4 ), 1.87 (m,
+
+
3
3
8H, NBu4 ), 1.49 (pseudo sextet, 8H, 7.4 Hz, NBu4 ), 1.03 (t, 12H,
trans to I, JF,Pt = 515 Hz, JF,F = 27 Hz), −164.9 (t, 1 p-F of the RF
+
7.4 Hz, NBu4 ) ppm. 19F NMR (298 K, (CD3)2CO, 376.5 MHz): δ
−115.0 (m, 2 o-F, JF,Pt = ca. 325 Hz), −115.1 (m, 2 o-F, JF,Pt = ca.
335 Hz), −167.1 (m, 4 m-F), −167.7 (m, 1 p-F), −167.8 (m, 1 p-F)
ppm.
trans to P, 3JF,F = 20 Hz), −166.1 (td, 2 m-F of the RF trans to P, 3JF,F
=
3
3
5
3
20 Hz, JF,P = 9 Hz), −166.7 (t, 1 p-F of the RF trans to I, JF,F = 19
Hz), −167.2 (m, 2 m-F of the RF trans to I, 4JF,Pt = 168 Hz, 3JF,F = 19
3
Hz, JF,F = 27 Hz) ppm.
Synthesis of [(RF)2M(μ-I)(μ-PPh2)M′(P,O-PPh2hq)]. M = M′ =
Pt, 7. I2 (0.029 g, 0.114 mmol) in CH2Cl2 (10 mL) was added
dropwise to a yellow solution of 1 (0.169 g, 0.114 mmol) in CH2Cl2 (5
mL). The solution was stirred at room temperature for 20 h, and the
orange solution was evaporated to ca. 1 mL. i-PrOH (10 mL) was
added, stirred for 30 min, and left in the freezer for 4 h. Complex 7
crystallized as a yellow solid which was filtered, washed with cold i-
PrOH (2 × 1 mL), and dried. Yield: 0.098 g, 63%. Found: C, 39.27; H,
1.96; N, 1.16. C45H26F10INOP2Pt2 requires C, 39.58; H, 1.92; N, 1.03.
HRMS(+), measured: m/z: 1387.9561 [M + Na]+, exact mass:
Reaction of 4 with I2. I2 (0.030 g, 0.118 mmol) was added to a
yellow solution of 4 (0.173 g, 0.118 mmol) in anhydrous CH2Cl2 (10
mL), and the resulting mixture was stirred under argon at room
temperature for 20 h. The resulting solution was evaporated to ca. 3
mL, anhydrous n-hexane (10 mL) was added, and a yellow oil was
formed. The liquors were eliminated, and the yellow oil was stirred
with anhydrous n-hexane (5 mL) for 30 min affording a yellow solid.
The n-hexane was eliminated, and the solid was dried in a vacuum.
The 31P{1H}NMR spectrum of this yellow solid showed to be a
mixture of [NBu4][(RF)2Pt(μ-I)(μ-PPh2)Pt(PPh2-pic)I], 10, and
[NBu4][(RF)2Pt(μ-I)(μ-PPh2)Pt(PPh2OH)I], 10-hydr, and satisfac-
tory analysis of 10 could in no case be obtained. Recrystallization of
this mixture from wet acetone and i-PrOH (1 mL/5 mL) afforded 10-
hydr which was filtered, washed with cold i-PrOH (2 × 0.5 mL), and
dried. 10-hydr. Yield: 0.111 g, 54%. Found: C, 38.81; H, 3.31; N, 0.98.
C52H57F10I2NOP2Pt2 requires C, 38.84; H, 3.57; N, 0.87.
1
1387.9554; H NMR (298 K, (CD3)2CO, 400 MHz): δ 10.53 (broad
d, 1H, H2, 4.9 Hz), 8.97 (d, 1H, H4, 8.4 Hz), 8.05 (d, 1H, H5, 8.0 Hz,
overlapped), 8.03 (m, 1H, H3, overlapped), 7.88 (d, 1H, H7, 8.0 Hz),
7.81 (pseudo t, 1H, H6, 8.0 Hz), 7.65−7.52 (m, 6H, o-Ph bonded to
PB, p-Ph bonded to PB), 7.46−7.34 (m, 8H, o-Ph bonded to PA, m-Ph
bonded to PB), 7.27 (t, 2H, p-Ph bonded to PA, 7.5 Hz), 7.09 (pseudo
t, 4H, m-Ph bonded to PA, 7.5 Hz) ppm. 19F NMR (298 K,
(CD3)2CO, 376.5 MHz): δ −115.4 (m, 2 o-F of the RF trans to P, 3JF,Pt
= 336 Hz, 3JF,F = 3JF,P = 18 Hz), −117.5 (d, 2 o-F of the RF trans to I,
10. HRMS(−), exact mass for the anion [C42H214F10NI2O2P2Pt2]−:
1469.8504 Da; measured: m/z: 1469.8517 (M)−. H NMR (298 K,
(CD3)2CO, 400 MHz): δ 8.62 (broad d, 1H, H2, 4.3 Hz), 8.01 (dd,
4H, o-Ph bonded to PB, 7.1 Hz, 8.5 Hz), 7.84−7.77 (m, 5H, o-Ph
bonded to PA, H4), 7.58−7.39 (m, 8H, p-Ph bonded to PB, m-Ph
bonded to PB, H3, H5), 7.10 (t, 2H, p-Ph bonded to PA, 6.9 Hz), 7.00
3
3JF,Pt = 528 Hz, JF,F = 27 Hz), −165.1 (t, 1 p-F of the RF trans to P,
3
3JF,F = 19 Hz), −166.1 (td, 2 m-F of the RF trans to P, JF,F = 19 Hz,
3
5JF,P = 9 Hz), −167.2 (t, 1 p-F of the RF trans to I, JF,F = 19 Hz),
+
(pseudo t, 4H, m-Ph bonded to PA, 7.3 Hz), 3.49 (m, 8H, NBu4 ),
4
3
−167.5 (m, 2 m-F of the RF trans to I, JF,Pt = 130 Hz, JF,F = 19 Hz,
+
+
3JF,F = 27 Hz) ppm.
1.87 (m, 8H, NBu4 ), 1.49 (pseudo sextet, 8H, 7.4 Hz, NBu4 ), 1.03
+
(t, 12H, 7.4 Hz, NBu4 ) ppm. 19F NMR (298 K, (CD3)2CO, 376.5
M = M′ = Pd, 8. I2 (0.039 g, 0.157 mmol) in CH2Cl2 (10 mL) was
added dropwise to a yellow solution of 2 (0.204 g, 0.157 mmol) in
CH2Cl2 (5 mL), and the resulting mixture was stirred at room
temperature for 20 h. The red solution was evaporated to ca. 1 mL,
passed through a silica column (ca. 15 cm ×3 cm2) and eluted with
CH2Cl2. The red solution (ca. 50 mL) was evaporated to ca. 1 mL,
Et2O (30 mL), and hexane (ca. 2 mL) was added and left in the freezer
for 4 h. A red solid, 8, was filtered, washed with cold n-hexane (2 × 1
mL), and dried. 0.040 g, 21% yield. Solutions of 8 slowly became dark.
Minor amounts of black palladium could be present in the samples of
8. Found: C, 44.34; H, 2.40; N, 1.18. C45H26F10INOP2Pd2 requires C,
45.48; H, 2.21; N, 1.18. HRMS(+), measured: m/z: 1211.8283 [M +
Na]+, exact mass: 1211.8359; 1H NMR (298 K, (CD3)2CO, 400
MHz): δ 10.46 (broad d, 1H, H2, 4.9 Hz), 8.88 (dd, 1H, H4, 8.3 Hz,
1.4 Hz), 8.00 (dd, 1H, H3, 8.3 Hz, 5.0 Hz), 7.98 (d, 1H, H5, 8.0 Hz,
1.4 Hz), 7.82 (ddd, 1H, H7, 7.7 Hz, 1.3 Hz, 0.7 Hz), 7.75 (pseudo t,
MHz): δ −114.9 (pseudo t, 2 o-F of the RF trans to P, 3JF,Pt = 340 Hz,
3JF,F = 3JF,P = 19 Hz), −116.4 (d, 2 o-F of the RF trans to I, 3JF,Pt = 505
Hz, 3JF,F = 30 Hz), −166.5 (t, 1 p-F of the RF trans to P, 3JF,F = 19 Hz),
3
5
−166.9 (m, 2 m-F of the RF trans to P, JF,F = 20 Hz, JF,P = 10 Hz),
−168.3 (pseudo t, 2 m-F of the RF trans to I, 4JF,Pt = 138 Hz, mean 3JF,F
3
= 24 Hz) −168.7 (t, 1 p-F of the RF trans to I, JF,F = 19 Hz) ppm.
10-hydr. HRMS(−), exact mass for the anion
[C36H21F10I2OP2Pt2]−: 1364.8289; measured: m/z: 1364.8294 (M)−.
1H NMR (298 K, (CD3)2CO, 400 MHz): δ 7.96 (dd, 4H, o-Ph
bonded to PA, 10.4 Hz, 7.9 Hz), δ 7.81 (dd, 4H, o-Ph bonded to PB,
12.4 Hz, 8.0 Hz), 7.54 (s, POH, detected from 1H EXSY spectrum, by
its exchange with H2O), 7.52 (t, 2H, p-Ph bonded to PB, 7.4 Hz), 7.45
(pseudo t, 4H, m-Ph bonded to PB, 7.4 Hz), 7.22 (t, 6H, p-Ph bonded
to PA, 7.2 Hz) 7.13 (pseudo t, 4H, m-Ph bonded to PA, 7.2 Hz), 3.49
+
+
(m, 8H, NBu4 ), 1.87 (m, 8H, NBu4 ), 1.49 (pseudo sextet, 8H, 7.4
5503
dx.doi.org/10.1021/ic4004005 | Inorg. Chem. 2013, 52, 5493−5506

Inorganic Chemistry
Article
+
+
Hz, NBu4 ), 1.03 (t, 12H, 7.4 Hz, NBu4 ) ppm. 19F NMR (298 K,
mL), solid NBu4I (0.037 mg, 0.100 mmol), and solid I2 (18 mg, 0.072
mmol) in acetone-d6 at 268 K, which showed the formation of 4-ox;
(iii) the monitoring of the reaction between 4 (0.030 g, 0.025 mmol in
0.5 mL), and solid I2 (6.4 mg, 0.025 mmol) in anhydrous thf at 298 K,
which showed the transformation of 4-ox into 10; (iv) the monitoring
of the reaction between 6 (0.030 g, 0.025 mmol in 0.5 mL), solid
NBu4I (0.037 mg, 0.100 mmol), and solid I2 (18 mg, 0.072 mmol) in
acetone-d6 at 268 K, which showed the formation of 6-ox-cis and
-trans; (v) the monitoring of the reaction between 6 (0.030 g, 0.025
mmol in 0.5 mL) and solid I2 (6.4 mg, 0.025 mmol) in acetone-d6 at
298 K, which showed the transformation of 6-ox into 12.
(CD3)2CO, 376.5 MHz): δ −115.2 (pseudo t, 2 o-F of the RF trans to
3
3
3
P, JF,Pt = 345 Hz, JF,F = JF,P = 19 Hz), −116.7 (d, 2 o-F of the RF
3
3
trans to I, JF,Pt = 503 Hz, JF,F = 29 Hz), −166.7 (t, 1 p-F of the RF
trans to P, 3JF,F = 19 Hz), −167.0 (td, 2 m-F of the RF trans to P, 3JF,F
=
19 Hz, 5JF,P = 9 Hz), −168.2 (pseudo t, 2 m-F of the RF trans to I, 4JF,Pt
3
= 136 Hz, mean JF,F = 24 Hz) −169.0 (t, 1 p-F of the RF trans to I,
3JF,F = 19 Hz) ppm.
Synthesis of [NBu4][(PPh2-pic)(RF)Pt(μ-I)(μ-PPh2)Pd(RF)I], 11. I2
(0.037 g, 0.146 mmol) in CH2Cl2 (10 mL) was added dropwise to
a yellow solution of 5 (0.200 g, 0.146 mmol) in CH2Cl2 (5 mL). The
solution was stirred under nitrogen at room temperature for 20 h and
then evaporated to dryness. The solid residue was recrystallized from
acetone/i-PrOH (1 mL/5 mL). Complex 11 crystallized as a yellow
solid which was filtered, washed with cold i-PrOH (2 × 0.5 mL), and
dried. 0.125 g, 53% yield. Found: C, 42.29; H, 3.65; N, 1.88.
C58H60F10I2N2O2P2PdPt requires C, 42.89; H, 3.72; N, 1.72.
HRMS(−), exact mass for the anion [C42H24F10I2NO2P2PdPt]−:
X-ray Structure Determinations. Crystal data and other details
of the structure analyses are presented in Table S1. Suitable crystals for
X-ray diffraction studies were obtained by slow diffusion of n-hexane
into concentrated solutions of the complexes in 3 mL of Me2CO or
CH2Cl2. Crystals were mounted at the end of a quartz fiber. The
radiation used in all cases was graphite monochromated MoKα (λ =
0.71073 Å). For 7, 9, and 11, X-ray intensity data were collected on an
Oxford Diffraction Xcalibur diffractometer. The diffraction frames
were integrated and corrected from absorption by using the CrysAlis
RED program.74 For 12, diffraction measurements were made on an
Enraf-Nonius CAD-4 diffractometer. Diffracted intensities were
measured in a hemisphere of reciprocal space. Three check reflections
remeasured after every 300 ordinary reflections showed no decay of
the diffracted intensities over the period of data collection. An
absorption correction was applied based on 548 azimuthal scan data.
The structures were solved by Patterson and Fourier methods and
refined by full-matrix least-squares on F2 with SHELXL-97.75 All non-
hydrogen atoms were assigned anisotropic displacement parameters
and refined without positional constraints, except as noted below. All
hydrogen atoms were constrained to idealized geometries and assigned
isotropic displacement parameters equal to 1.2 times the Uiso values of
their attached parent atoms (1.5 times for the methyl hydrogen
atoms). In the structures of 7·2Me2CO and 9·Me2CO·0.25n-C6H14,
restraints were applied in the geometry of the acetone solvent and n-
hexane molecules respectively. In the structure of 12, the
tetrabutylammonium cation was found to be very badly disordered,
with two positions sharing some of the carbon atoms of the butyl
“branches”; moreover, some of the nonshared carbon atoms are also
disordered over two positions. Partial occupancy assignments and
restraints in the geometry were used for this moiety. Full-matrix least-
squares refinement of these models against F2 converged to final
residual indices given in Table S1.
1381.7887 Da; measured: m/z: 1381.7895 (M)−. H NMR (298 K,
1
(CD3)2CO, 400 MHz): δ 8.60 (broad d, 1H, H2, 3.9 Hz), 7.89−7.79
(m, 6H, o-Ph bonded to PB, H4, H5), 7.64−7.54 (m, 3H, p-Ph bonded
to PB, H3), 7.51−7.38 (m, 8H, o-Ph bonded to PA, m-Ph bonded to
PB), 7.06 (t, 2H, p-Ph bonded to PA, 7.2 Hz), 6.88 (pseudo t, 4H, m-
+
+
Ph bonded to PA, 7.1 Hz), 3.49 (m, 8H, NBu4 ), 1.87 (m, 8H, NBu4 ),
+
+
1.49 (pseudo sextet, 8H, 7.4 Hz, NBu4 ), 1.03 (t, 12H, 7.4 Hz, NBu4 )
ppm. 19F NMR (298 K, (CD3)2CO, 376.5 MHz): δ −112.2 (d, 2 o-F
of the RF trans to I, 3JF,F = 28 Hz), −115.5 (dd, 2 o-F of the RF trans to
P, 3JF,Pt = 256 Hz, 3JF,F = 24 Hz, 4JF,P = 17 Hz), −164.9 (t, 1 p-F of the
3
RF trans to P, JF,F = 19 Hz), −166.1 (m, 2 m-F of the RF trans to P,
3JF,F = 24 Hz, JF,F = 19 Hz), −167.0 to −167.3 (m, 1 p-F of the RF
3
trans to I, 2 m-F of the RF trans to I) ppm.
Synthesis of [NBu4][(RF)2Pt(μ-I)(μ-PPh2)PtI(Ph2P-acac)] (12). I2
(0.035 g, 0.140 mmol) in CH2Cl2 (10 mL) was added dropwise to
a colorless solution of [NBu4][(RF)2Pt(μ-PPh2)2Pt(O,O′-acac)] (6)
(0.201 g, 0.140 mmol) in CH2Cl2 (20 mL), and the resulting mixture
was stirred at room temperature for 20 h. The obtained yellow
solution was evaporated to ca. 2 mL, CHCl3 (8 mL) was added, and
evaporated to ca. 6 mL. The mixture was stirred for 30 min, and 12
crystallized as a yellow solid which was filtered, washed with cold
CHCl3 (2× 1 mL), and dried. 0.168 g, 69% yield. Found: C, 40.26; H,
3.82; N, 1.18. C57H63F10I2NO2P2Pt2 requires C, 40.51; H, 3.76; N,
0.83. HRMS(−), exact mass for the anion [C41H27F10I2O2P2Pt2]−:
1446.870 Da; measured: m/z: 1446.8720 (M)−. H NMR (298 K,
1
(CD3)2CO, 400 MHz): δ 7.98 (dd, 4H, o-Ph bonded to PA, 10.8 Hz,
8.5 Hz), 7.66 (dd, 4H, o-Ph bonded to PB, 12.2 Hz, 7.3 Hz), 7.58 (t,
2H, p-Ph bonded to PB, 6.9 Hz), 7.49 (pseudo t, 4H, m-Ph bonded to
PB, 7.3 Hz), 7.36−7.22 (m, 6H, p-Ph bonded to PA, m-Ph bonded to
ASSOCIATED CONTENT
* Supporting Information
■
S
Crystallographic data of 7·2Me2CO, 9·Me2CO·0.25n-C6H14,
11·CH2Cl2, and 12 (CIF format); NMR spectra of 1−5, 7, 10−
12, 1-ox, 4-ox, 6-ox; HRMS spectrograms of 1−5, 7−12, 1-ox,
4-ox, 6-ox. This material is available free of charge via Internet
at http://pubs.acs.org
+
PA) 4.96 (d, 1H, CH, 2.0 Hz), 3.49 (m, 8H, NBu4 ), 1.87 (m, 8H,
+
NBu4+), 1.72 (s, 3H, (OC)-CH3)), 1.49 (pseudo sextet, 8H, 7.4 Hz,
+
NBu4 ), 1.40 (s, 3H, CC−CH3), 1.03 (t, 12H, 7.4 Hz, NBu4 ) ppm.
19F NMR (298 K, (CD3)2CO, 376.5 MHz): δ −115.3 (m, 2 o-F of the
RF trans to P, 3JF,Pt = 340 Hz, 3JF,F = 3JF,P = 18 Hz), −116.9 (d, 2 o-F of
the RF trans to I, 3JF,Pt = 497 Hz, 3JF,F = 29 Hz), −166.5 (t, 1 p-F of the
AUTHOR INFORMATION
Corresponding Author
*E-mail: cfortuno@unizar.es (C.F.); p.mastrorilli@poliba.it
(P.M.).
■
3
RF trans to P, JF,F = 19 Hz), −166.9 (td, 2 m-F of the RF trans to P,
3JF,F = 19 Hz, 5JF,P = 9 Hz), −168.1 (pseudo t, 2 m-F of the RF trans to
I, 4JF,Pt = 137 Hz, mean 3JF,F = 24 Hz) −168.7 (t, 1 p-F of the RF trans
3
to I, JF,F = 19 Hz) ppm.
Notes
NMR Monitoring of the Reaction Solutions. An NMR tube
kept at 268 K was charged with an acetone-d6 solution of 1 (0.030 g,
0.024 mmol in 0.5 mL), solid NBu4I (0.037 mg, 0.100 mmol), and
solid I2 (18 mg, 0.072 mmol) and vigorously shaken. The resulting red
solution was put in the NMR probe precooled at 268 K, and
multinuclear NMR spectra were recorded. The mixture revealed the
immediate formation of 1-ox that, under these conditions, was found
stable at 268 K for at least one week. The same procedure was
followed for (i) the monitoring of the reaction between 1 (0.030 g,
0.024 mmol in 0.5 mL), and solid I2 (6.1 mg, 0.024 mmol) in acetone-
d6 at 298 K, which showed the transformation of 1-ox into 7; (ii) the
monitoring of the reaction between 4 (0.030 g, 0.025 mmol in 0.5
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
This work was supported by the Spanish MICINN (Project
CTQ2008-06669-C02-01), the Ministerio de Economia y
■
́
Competitividad (Project CTQ2012-35251), and the Cobierno
́
de Aragon
los Compuestos Organometal
́
(Grupo de Consolidado: Quimica Inorgan
́
ica y de
́
icos). A.A. gratefully acknowl-
edges MICINN for a FPU grant. Italian MIUR (PRIN project
n. 2009LR88XR) is also acknowledged for financial support.
5504
dx.doi.org/10.1021/ic4004005 | Inorg. Chem. 2013, 52, 5493−5506

Inorganic Chemistry
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