Synthesis and structures of platinum diphenylacetylene and dithiolate complexes bearing diphosphinidenecyclobutene ligands (DPCB-Y)

Article abstract of DOI:10.1039/c0nj00118j

A series of platinum complexes of the type [Pt(D)(A)] having two kinds of π-conjugated ligand systems with donor and acceptor properties are prepared, using p-substituted diphenylacetylenes (tolan-X; X = OMe, H, CF₃), 1,2-benzenedithiolato (bdt) and 1,3-dithia-2-thione-4,5-dithiolato (dmit) as π-donor ligands (D), and 1,2-diaryl-3,4-bis[(2,4,6-tri-tert-butylphenyl) phosphinidene]cyclobutenes (DPCB-Y; diaryl = 2C₆H₄-p-Y (Y = OMe, H, CF₃), biphenyl-2,2′-diyl) as π-acceptor ligands (A). The electronic structures of the resulting complexes are examined in detail to investigate π-orbital interaction occurring in DPCB-Y complexes with a low-coordinate phosphorus ligand. The ³¹P NMR chemical shifts are highly sensitive to the Pt-P distances of the complexes, and linearly correlated with the bond lengths. The UV-vis absorption spectra of [Pt(tolan-X)(DPCB-Y)] display π-π* transitions in the visible region, which are shifted to longer wavelengths as the electron-donating ability of X and electron-withdrawing ability of Y increase, respectively. The complex [Pt(tolan-OMe)(DPCB-CF₃)] with a donor-acceptor combination of substituents exhibits particularly low-energy absorption. The absorption is further red-shifted for [Pt(bdt)(DPCB-phen)] and [Pt(dmit)(DPCB-phen)] having dithiolates as strong π-donor ligands.

Full text of DOI:10.1039/c0nj00118j

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PAPER
www.rsc.org/njc | New Journal of Chemistry
Synthesis and structures of platinum diphenylacetylene and dithiolate
complexes bearing diphosphinidenecyclobutene ligands (DPCB-Y)wzy
Yumiko Nakajima, Mitsuharu Nakatani, Kyohei Hayashi, Yu Shiraishi,
Ryo Takita, Masaaki Okazaki and Fumiyuki Ozawa*
Received (in Victoria, Australia) 13th February 2010, Accepted 27th April 2010
DOI: 10.1039/c0nj00118j
A series of platinum complexes of the type [Pt(D)(A)] having two kinds of p-conjugated ligand
systems with donor and acceptor properties are prepared, using p-substituted diphenylacetylenes
(tolan-X; X = OMe, H, CF3), 1,2-benzenedithiolato (bdt) and 1,3-dithia-2-thione-4,5-dithiolato
(dmit) as p-donor ligands (D), and 1,2-diaryl-3,4-bis[(2,4,6-tri-tert-butylphenyl)phosphinidene]-
cyclobutenes (DPCB-Y; diaryl = 2C6H4-p-Y (Y = OMe, H, CF3), biphenyl-2,20-diyl) as
p-acceptor ligands (A). The electronic structures of the resulting complexes are examined in detail
to investigate p-orbital interaction occurring in DPCB-Y complexes with a low-coordinate
phosphorus ligand. The 31P NMR chemical shifts are highly sensitive to the Pt–P distances of the
complexes, and linearly correlated with the bond lengths. The UV-vis absorption spectra of
[Pt(tolan-X)(DPCB-Y)] display p–p* transitions in the visible region, which are shifted to longer
wavelengths as the electron-donating ability of X and electron-withdrawing ability of Y increase,
respectively. The complex [Pt(tolan-OMe)(DPCB-CF3)] with a donor–acceptor combination of
substituents exhibits particularly low-energy absorption. The absorption is further red-shifted for
[Pt(bdt)(DPCB-phen)] and [Pt(dmit)(DPCB-phen)] having dithiolates as strong p-donor ligands.
between diphosphanes and diimines.7 On the other hand,
Introduction
although the structural variation between uncoordinated and
Low-coordinate phosphorus compounds have attracted recent
coordinated ligands was consistent with the occurrence of
interest in organometallic chemistry owing to their unique
p-back donation from platinum, the p-accepting abilities of
ligand properties differing significantly from common tertiary
DPCB-Y ligands remained to be explored.
phosphines.1 We have reported that 1,2-diaryl-3,4-bis-
More recently, we examined the electronic structures of
[(2,4,6-tri-tert-butylphenyl)phosphinidene]cyclobutenes (DPCB-Y,
[Pt(alkyne)(DPCB-phen)] complexes by UV-vis absorption
Fig. 1) having an extended p-conjugated system with two
spectroscopy and found the occurrence of extended
PQC bonds serve as particularly useful ligands, leading to
highly efficient catalyses in combination with group 8, 9 and 10
p-conjugation among the platinum, alkyne and DPCB-phen
ligand.8 It was suggested that the p-conjugation involves
metals.2 Representative examples include hydroamination of
dp–pp interaction between platinum and the out-of-plane p*
of alkyne ligand (p>: the alkyne p* orbital perpendicular to
the coordination plane), while such orbital interaction has
1,3-dienes (Pd),3 dehydrative allylation with allylic alcohols
(Pd),4 conjugate addition of benzyl carbamate to a,b-unsaturated
ketones (Pd, Rh)5 and Z-selective hydrosilylation of alkynes
been known to be insignificant in most cases, because the
(Ru).6 In this connection, we have been interested in evaluating
platinum dp orbital is occupied and undergoes repulsive
interaction with the alkyne p> orbital.9 We reasoned that
electronic properties of DPCB-Y ligands in real coordination
donor–acceptor interaction10 between the electron-rich pp
systems.
DPCB-Y undergoes bidentate coordination via two types of
orbital interaction with transition metals. One is s-donation of
lone-pair electrons on the phosphorus to vacant metal orbitals,
and the other is p-back donation from occupied metal d
orbitals to the p* orbitals of DPCB-Y. The previous study
of [PtMe2(DPCB-Y)] revealed intermediate s-donating ability
International Research Center for Elements Science (IRCELS),
Institute for Chemical Research, Kyoto University, Uji,
Kyoto 611-0011, Japan. E-mail: ozawa@scl.kyoto-u.ac.jp
w This paper is dedicated to the memory of the late Professor Pascal
Le Floch, Ecole Polytechnique.
z This article is part of a themed issue on Main Group chemistry.
y Electronic supplementary information (ESI) available: Details of
DFT calculations. CCDC reference numbers 735887 and
765285–765289. For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c0nj00118j
Fig. 1 Structures of DPCB-Y ligands.
ꢀc
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Table 1 List of the complexes employed in this study
X
Y
OMe
H
CF3
OMe
H
CF3
OMe
H
CF3
OMe
H
OMe
OMe
OMe
H
H
H
CF3
CF3
CF3
phen
phen
1a
1b
1c
2a
2b
2c
3a
3b
3c
4a
4b
5a
5b
6a
6b
Scheme 1
(DPCB-phen), in which the benzene rings on the acetylenic
carbons are tilted only by 7.6(1) and 5.3(1)1 from the
coordination plane. Complexes 2c and 3b exhibited the
structural features similar to 2a.
Table 2 compares the structural parameters of 2a, 2c, 3b and
4a with those of phosphine analogues.13–16 The C(1)–C(2)
lengths of DPCB-Y complexes range from 1.277(8) to
1.299(3) A; the values are similar to those of phosphine
analogues (1.280(5)–1.308(9) A). The bent back angles of the
phenyl groups of tolan-X against the C(1)–C(2) axis (i.e., the a
values in Table 2) are also in a comparable range. These
structural parameters are known to reflect the efficiency of
p-back donation from platinum to the in-plane p* orbital of
tolan-X (p8: the p* orbital parallel to the coordination
plane).17 Furthermore, the p-back donation reflects the
s-donating ability of supporting ligands. Thus, the X-ray data
indicate that DPCB-Y ligands are good s-donors comparable
to phosphines.
Table 3 summarizes the 13C{1H} NMR data for acetylenic
carbons and the 31P{1H} NMR data for DPCB-Y ligands. The
13C NMR signals appear at d 121.5–125.4 with the 1JPtC values
of 353–366 Hz. The chemical shift values are somewhat
smaller than those of the tolan-H complexes with dppe and
PPh3 ligands (d 135.6 and 127.1, respectively). An interesting
phenomenon emerging from the 31P NMR data is the upfield
shift upon coordination. Thus the signals of 1–4 appear more
clearly in an upper magnetic field than those of free DPCB-Y.
This situation is opposite to that observed for dppe as a
tertiary phosphine ligand, which exhibits a downfield shift
[Pt(bdt)(DPCB-H)]
[Pt(dmit)(DPCB-H)]
[Pt(bdt)(DPCB-phen)]
[Pt(dmit)(DPCB-phen)]
bdt
dithiolato.
=
1,2-benzenedithiolato, dmit
=
1,3-dithia-2-thione-4,5-
system of alkyne and the electron-poor pp system of
DPCB-phen facilitates the p-conjugation through the dp
orbital of platinum.
To investigate further the p-orbital interaction in DPCB-Y
complexes, we examined in this study two types of DPCB-Y
platinum complexes having p-donor ligands. First, a series of
[Pt(tolan-X)(DPCB-Y)] complexes (1–3) were prepared in
combination of each three kinds of p-substituents X and Y
as listed in Table 1. The UV-vis absorption spectra exhibit
clear dependence on substituents, which is consistent with the
p-conjugation mediated by donor–acceptor interaction between
tolan-X and DPCB-Y. Secondly, synthesis and structures of
[Pt(dithiolato)(DPCB-Y)] complexes (5 and 6) were examined.
Since dithiolates are known to be strong p-donor ligands,11 we
expected that donor–acceptor interaction may take place more
efficiently than in tolan-X complexes.
Results and discussion
Synthesis and structures of alkyne complexes
Besides [Pt(tolan-X)(DPCB-phen)] (4) previously reported,8
complexes 1–3 having three kinds of DPCB-Y ligands
(Y = OMe, H, CF3) were prepared from [Pt(cod)2] by
stepwise displacement of the cod ligands with tolan-X
(1 equiv.) and then with DPCB-Y (1 equiv.) (Scheme 1).12
Although ligand exchange reactions were examined in the
opposite order, intermediate [Pt(cod)(DCPB-Y)] was poorly
reactive, and an excess amount of tolan-X was required for the
subsequent step.
Complexes 1–3 were identified by NMR spectroscopy and
elemental analysis. Crystal structures of 2a, 2c and 3b were
examined by X-ray diffraction analysis. Fig. 2 shows the
structure of 2a as a representative example. The acetylenic
carbons, platinum and diphosphinidenecyclobutene skeleton
are in a planar arrangement; the dihedral angle between
PtC(1)C(2) plane (A) and cyclobutene ring (D) is 2.2(1)1. On
the other hand, the phenyl groups of tolan-H (B and C) are
skewed from plane A by 26.0(1) and 9.3(1)1, respectively. The
torsion angles are clearly larger than those observed for 4a
having the DPCB-Y ligand with a phenanthrene skeleton
Fig. 2 ORTEP drawing of 2a with the thermal ellipsoids at the 50%
probability level. Hydrogen atoms are omitted for clarity.
ꢀc
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Table 2 Selected bond distances (A) and angles (1) for the X-ray structures of 2a, 2c, 3b and related Pt(0) phosphine complexes
Compound
C(1)–C(2) Pt–C(1), Pt–C(2) Pt–P(1), Pt–P(2)
a
b
A–B dihedral A–C dihedral
2a (X = OMe, Y = H)
2c (X = CF3, Y = H)
3b (X = H, Y = CF3)
1.297(5)
1.282(6)
1.277(8)
2.048(3), 2.027(3) 2.300(1), 2.2704(9)
2.034(4), 2.036(4) 2.279(1), 2.277(1)
2.050(5), 2.036(5) 2.266(2), 2.277(2)
36.7(4), 32.3(4) 82.96(3)
30.2(4), 30.6(4) 82.79(4)
30.7(5), 30.5(5) 82.97(6)
26.0(1)
10.7(2)
9.8(2)
9.3(1)
8.7(2)
14.1(2)
5.3(1)
4a (X = OMe, Y = phen) 1.299(3)
2.053(2), 2.038(2) 2.3117(6), 2.2884(6) 28.3(2), 33.0(2) 82.95(5)
7.6(1)
[Pt(tolan-H)(dppe)] (A)
[Pt(tolan-H)(dppe)] (B)
[Pt(tolan-H)(dppbz)]
[Pt(tolan-H)(dppp)]
[Pt(tolan-H)(PPh3)2]
1.284(9)
1.308(9)
1.301(4)
1.301(7)
1.280(5)
2.038(6), 2.039(6) 2.265(2), 2.267(2)
2.029(6), 2.032(6) 2.262(2), 2.261(2)
2.038(3), 2.041(3) 2.260(1), 2.266(1)
2.041(3), 2.041(3) 2.2705(9), 2.2705(9) 35.5(2), 35.5(2) 96.02(5)
2.047(3), 2.048(3) 2.2910(8), 2.2820(9) 37.7(3), 37.4(3) 106.60(3)
33.1(7), 35.7(6) 86.44(6)
35.6(7), 36.1(6) 86.35(6)
34.6(3), 33.6(3) 86.56(4)
31.1(3)
35.0(3)
27.3(2)
31.6(3)
The dppe complex contains two independent molecules (A and B) in the crystal. dppe = 1,2-bis(diphenylphosphino)ethane, dppbz = 1,2-
bis(diphenylphosphino)benzene, dppp = 1,3-bis(diphenylphosphino)propane.
upon coordination with platinum. There is a tendency that
more electron-withdrawing tolan-X causes an upfield shift to a
greater extent. As we discuss below for Pt(II) complexes, the
extent of upfield shift is correlated with Pt–P lengths and thus
1
with JPtP values. For example, in each series of tolan-X
complexes with the same DPCB-Y ligand in Table 3, the 31P
1
NMR signal tends to be shifted upfield as the JPtP value
increases. It was confirmed that the 1JPtP values exhibit a good
Hammett correlation with the sp values18 of substituent X
(Fig. 3).
Synthesis and structures of dithiolate complexes
DPCB-H and DPCB-phen complexes bearing 1,2-benzene-
dithiolato (bdt) and 1,3-dithia-2-thione-4,5-dithiolato (dmit)
ligands were synthesized by anionic ligand exchange of
[PtCl2(DPCB-Y)] with thiolate sources (Scheme 2). The reactions
with 1,2-benzenedithiol proceeded in THF in the presence
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to give 5a and 6a,
each in 72% yield, where slow addition of a large excess
Fig. 3 Hammett plots for the substituent effects of tolan-X on the
1JPtP values of 1–3.
amount of DBU (>50 equiv.) at low temperature (ꢁ78 1C)
was essential to obtain the desired complexes in high yields,
otherwise the reactions were not completed. On the other
hand, [PtCl2(DPCB-Y)] cleanly reacted with a stoichiometric
amount of [NEt4]2[Zn(dmit)2] in CH2Cl2 at room temperature
to afford 5b and 6b in 92 and 77% yields, respectively.
Complexes 5 and 6 were identified by NMR spectroscopy
and elemental analysis. The NMR data were fully consistent
with C2v symmetry of the complexes in solution, having a
planar geometry except for Mes* groups on the phosphorus
atoms. Thus, the two ortho t-Bu groups of the Mes* groups
arrangement of the bdt, platinum and DPCB-H ligand with
one twofold axis on the plane. The dihedral angle between the
benzene ring of bdt (A) and the cyclobutene ring of DPCB-H
ligand (B) is 1.8(1)1, whereas the phenyl groups of DPCB-H
(C and C0) are twisted by 23.2(1)1 against plane B. The latter
value is notably smaller than that of free DPCB-H (40.0 and
42.61).7
Table 4 compares the Pt–S and Pt–P lengths of 5a with those
of Pt(II) complexes having dimethyl,7,19 dithiolato,20–24 and
dichloro ligands.25,26 The Pt–S bonds of 5a (2.2835(5) A) are
somewhat shorter than those of dppe and dppf complexes
(2.308(1)–2.316(6) A), but clearly longer than those of nitrogen-
based ligand complexes (2.232(2)–2.251(4) A). The Pt–P
1
were observed equivalently in the H and 13C NMR spectra,
showing orthogonal orientation of the Mes* groups against
the coordination plane.
Fig. 4 shows the X-ray crystal structure of 5a. In agreement
with the NMR data, the complex adopts a significantly planar
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Table 3 13C{1H} and 31P{1H} NMR data for 1–4 and free DPCB-Y
Compound
dCRC
1JPtC
dP
1JPtP
DPCB-OMe
—
—
353
162.6
153.0
152.6
149.8
—
1a (X = OMe, Y = OMe)
1b (X = H, Y = OMe)
1c (X=CF3, Y = OMe)
121.6
123.9
124.9
3458
3480
3522
366
a
DPCB-H
––
––
361
169.5
160.0
159.7
157.2
––
2a (X=OMe, Y = H)
2b (X=H, Y = H)
2c (X=CF3, Y = H)
121.8
124.0
125.4
3460
3485
3528
365
a
DPCB-CF3
––
––
362
180.7
169.6
169.5
167.0
––
3a (X=OMe, Y = CF3)
3b (X=H, Y = CF3)
3c (X=CF3, Y = CF3)
122.1
124.1
124.8
3473
3495
3541
362
a
DPCB-phen
4a (X=OMe, Y = phen)
4b (X = H, Y = phen)
––
121.5
122.3
––
358
361
173.2
156.6
155.7
––
3436
3455
dppe
[Pt(tolan-H)(dppe)]
––
135.6
––
313
–12.5
49.6
––
3110
The chemical shifts and coupling constants are given in ppm and Hz,
respectively. The data were observed in CD2Cl2 at 20 1C.a The
coupling constant was obscured due to broadening of the satellite
signals.
Fig. 4 ORTEP drawing of 5a with the thermal ellipsoids at the 50%
probability level. Hydrogen atoms are omitted for clarity. The atoms
labeled with a prime character (0) are at (3/2 ꢁ x, 1 ꢁ y, z).
Table 4 Selected bond distances (A) for the X-ray structures of 5a
and related Pt(II) complexes
Compound
Pt–S
Pt–P
[PtMe2(DPCB-H)]
[Pt(bdt)(DPCB-H)] (5a)
[PtCl2(DPCB-H)]
—
2.2835(5)
—
2.2909(8)
2.2514(5)
2.243(1), 2.245(1)
[PtMe2(dppe)]
—
2.246(2), 2.254(2)
2.260(9), 2.259(6)
2.208(6)
[Pt(bdt-NNtol)(dppe)]
[PtCl2(dppe)]
[Pt(bdt)(dppf)]
2.310(1), 2.316(6)
—
2.309(1), 2.308(1)
2.3126(7), 2.3298(9)
[Pt(bdt)(mesBIAN)]
[Pt(bdt)(bipy)]
[Pt(bdt-t-Bu2)(phen-Ph2)]
2.232(2), 2.244(2)
2.244(2), 2.250(2)
2.251(4), 2.244(4)
—
—
—
bdt = 1,2-benzenedithiolato, bdt-NNtol = 4-(tolylazo)benzene-1,2-
dithiolato, mesBIAN = bis(mesityl)biazanaphthenequinone, bdt-t-
Bu2 = 3,5-di-tert-butylbenzene-1,2-dithiolato, phen-Ph2 = 4,7-diphenyl-
1,10-phenanthroline.
Scheme 2
lengths are elongated as the trans-influence of diagonal ligands
increases in the order Cl o bdt o Me.
(DPCB-H) and 49.9 ppm (DPCB-phen) compared with those
of free DPCB-Y ligands, respectively. Since the chemical shifts
of phosphorus atoms are principally controlled by the
paramagnetic term, the linear dependence of the chemical
shifts upon Pt–P distances will be useful for evaluating
p-orbital interaction between DPCB-Y and platinum.
Table 5 summarizes the 31P NMR chemical shifts (dP), 1JPtP
values, and averaged Pt–P bond lengths. It is seen from the
data of DPCB-H complexes that 1JPtP values are proportional
to Pt–P lengths as expected. Furthermore, dP values of
DPCB-H and DPCB-phen complexes are in inverse proportion
1
to JPtP values (Fig. 5). Thus, it is evident that dP values of
UV-vis absorption spectra of 1–3
DPCB-Y ligands are inversely proportional to Pt–P lengths.
Although a similar tendency is observed for dppe complexes,
the variation in chemical shifts is rather small.
Fig.
6
shows typical UV-vis absorption spectra of
[Pt(tolan-X)(DPCB-Y)] (1–3). Schematic diagrams of important
molecular orbitals are given in Fig. 7. Based on time-dependent
DFT calculations (TD-DFT) for a model compound of 2b
having mesityl (Mes) groups in place of Mes*, three absorption
bands marked I, II and III were identified. Band I is composed
of several absorption bands, including a relatively large
contribution of the HOMO(ꢁ1)/LUMO transition (23%).
As we described above, unlike dppe as a phosphine ligand,
DPCB-Y ligands exhibit an upfield shift in the 31P NMR
spectra upon coordination. Dimethyl complexes with the
longest Pt–P bonds exhibit almost the same dP values as free
ligands. On the other hand, the signals of dichloro complexes
with the shortest Pt–P bonds are shifted upfield by 40.6
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Fig. 6 Representative UV-vis absorption spectra of 1–3 in CHCl3.
Fig. 5 Relation between 31P NMR chemical shifts (dP) and coupling
constants (1JPtP) for Pt(II) DPCB-Y complexes.
Table 5 31P{1H} NMR data for Pt(II) complexes having DPCB-Y
and dppe ligands
Compound
dP
1JPtP
Pt–P
DPCB-H
169.5
171.6
146.1
140.4
128.9
—
—
2.291
2.251
[PtMe2(DPCB-H)]
[Pt(bdt)(DPCB-H)] (5a)
[Pt(dmit)(DPCB-H)] (6a)
[PtCl2(DPCB-H)]
1590
3265
3414
4496
a
2.244
DPCB-phen
173.2
167.0
144.7
138.0
123.3
—
—
a
[PtMe2(DPCB-phen)]
[Pt(bdt)(DPCB-phen)] (5b)
[Pt(dmit)(DPCB-phen) (6b)
[PtCl2(DPCB-phen)]
1489
3149
3350
4444
a
a
a
dppe
ꢁ12.5
54.0
43.9
—
—
[PtMe2(dppe)]
[Pt(bdt-NNtol)(dppe)]
[PtCl2(dppe)]
1783
2775
3600
2.250
2.260
2.208
43.8
Fig. 7 Frontier orbitals of 2b generated by DFT calculations for a
model compound having Mes groups instead of Mes* groups.
The data were observed in CD2Cl2 at 20 1C. The chemical shifts,
coupling constants, and bond distances are given in ppm, Hz, and A,
respectively. The Pt–P length is the average of two bonds.a Not
measured.
increases. This tendency, which is most remarkable for band I
of 3a–c bearing a DPCB-CF3 ligand, is opposite to the general
observations on substituent effects. As we mentioned above,
the absorption band I includes a relatively large contribution
of the HOMO(ꢁ1)/LUMO transition, and the LUMO is
mainly composed of the p orbital of DPCB-Y. Thus, it is
reasonable that the CF3 group results in a decrease in the
LUMO level, and therefore causes the red shift in UV-vis
absorption spectra. It is seen from Fig. 6 that this remarkable
substituent effect of the CF3 group as Y is of particular
significance in 3a with an electron-donating OMe group as
X, showing the occurrence of donor–acceptor interaction
between the tolan-X and DPCB-Y ligands.
Band II includes major and minor contributions of the
HOMO/LUMO(+1) (36%) HOMO(ꢁ1)/LUMO (11%)
transitions, respectively. On the other hand, band III mainly
consists of the HOMO/LUMO transition (45%), which is
symmetry-forbidden, weak absorption.
Table 6 lists the absorption maxima (lmax) of band I and
band II, showing the effects of substituents X and Y on the
absorption. Since all molecular orbitals participating in the
absorption are p-symmetrical ones, no notable solvatochromic
change in the absorption spectra was observed in cyclohexane,
chloroform and acetone. The lmax values are red-shifted as the
electron-donating ability of X increases. This tendency is the
one that is commonly observed for p-conjugated systems. On
the other hand, the absorption tends to be shifted to the
longer wavelengths as the electron-withdrawing nature of Y
UV-vis absorption spectra of 5 and 6
Fig. 8 compares UV-vis spectra of 6a and 6b with 4b. Unlike
1–3 having DPCB-Y ligands (Y = OMe, H, CF3), the
DPCB-phen complexes display strong absorption bands in
ꢀc
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Table 6 lmax values (nm) for band I and band II of 1–3
X (sp)
Y (sp)
OMe (ꢁ0.27)
H (0)
CF3 (0.54)
Band I: lmax (log e)
OMe (ꢁ0.27)
H (0)
CF3 (0.54)
440 (4.29) (1a)
430 (4.47) (1b)
422 (4.58) (1c)
442 (4.38) (2a)
432 (4.36) (2b)
424 (4.53) (2c)
459 (4.34) (3a)
448 (4.34) (3b)
433 (4.53) (3c)
Band II: lmax (log e)
Fig. 9 Frontier orbitals of 6a generated by DFT calculations for a
OMe (–0.27)
H (0)
CF3 (0.54)
542 (3.87) (1a)
529 (3.95) (1b)
519 (4.01) (1c)
545 (3.94) (2a)
531 (3.80) (2b)
519 (3.86) (2c)
548 (3.75) (3a)
534 (3.61) (3b)
521 (3.74) (3c)
model compound having Mes groups instead of Mes* groups.
is particular effective for enhancement in the extended
p-conjugation within the molecule. The HLG value of 6b
(1.77 eV) was clearly lower than those of 4a (2.06 eV) and
4b (1.99 eV), and comparable to that of [Pt(tolan-NMe2)-
(DPCB-phen)] having strongly electron-donating NMe2
groups on the tolan-X ligand (1.82 eV).8
The data were observed in CHCl3 at room temperature.
the region of 500–700 nm. This is due to the reverse on the
orbital levels between the LUMO and LUMO(+1). As seen
from the orbital diagrams in Fig. 9, the orbital symmetry of
the LUMO harmonizes with that of the HOMO, giving a
symmetry-allowed transition with strong intensity. TD-DFT
calculations for the models of 6a and 6b having Mes instead of
Mes* revealed the absorption bands involving 37 and 41%
contributions of the HOMO/LUMO transition, respectively.
Recently, related platinum dithiolates supported by nitrogen-
based ligands were reported to exhibit strong MLCT bands in
a similar region with remarkable solvatochromism.22 On the
other hand, the present DPCB-phen complexes were insensitive
to solvent polarity among chloroform, THF and acetone.
Therefore, in conjunction with the orbital distribution found
in Fig. 9, the HOMO/LUMO transition of DPCB-phen
complexes are assigned to p–p* transition.
Table 7 lists the data for lowest-energy absorption of 5 and
6. Complexes 5a and 6a with a 1,2-benzenedithiolato ligand
(bdt) exhibit the lmax values of 556 and 583 nm, respectively.
These values are red-shifted by 12 and 21 nm, respectively,
when the bdt ligand is replaced by 1,3-dithia-2-thione-4,5-
dithiolato (dmit) as a stronger p-donor than bdt. As judging
from the values of absorption maxima and HOMO–LUMO
gaps (HLG), the combination of dmit and DPCB-phen ligands
Conclusions
The DPCB-Y complexes of platinum possess rather unique
electronic properties, clearly different from diphosphine and
diimine analogues. Most of them are rationalized by assuming
the occurrence of dp–pp interaction between the DPCB-Y
ligands and platinum. Thus, the 31P NMR chemical shifts are
highly sensitive to Pt–P distances, and linearly correlated with
the bond lengths. Moreover, the complexes exhibit the absorption
bands at significantly longer wavelengths. Unlike the diimine
complexes showing
a MLCT band, these absorptions
are assignable to p–p* transitions derived from extended
p-conjugation within the molecules. Further applications of
these unique ligand properties to organometallic chemistry
will be reported in due course.
Experimental
All manipulations were performed under a nitrogen or argon
atmosphere using standard Schlenk techniques. NMR spectra
were recorded on a Bruker AVANCHE 400 spectrometer
(1H, 400.13 MHz; 13C, 100.62 MHz; 31P, 161.98 MHz).
Chemical shifts are reported in d, referenced to 1H (of residual
protons) and 13C signals of deuterated solvents as internal
standards or to the 31P signal of 85% H3PO4 as an external
standard. UV-vis absorption spectra were measured on a
JASCO V550 spectrometer. Elemental analysis was performed
by the ICR Analytical Laboratory, Kyoto University.
Synthetic procedures for DPCB-Y ligands were previously
reported.7,27 [Pt(cod)2] and [Et4N]2[Zn(dmit)2] were prepared
according to the literature.28,29 [PtCl2(DPCB-H)] and
Table 7 Lowest-energy absorption data for 5 and 6
Compound
lmax (log e)
ledge
HLG
[Pt(bdt)(DPCB-H)] (5a)
[Pt(dmit)(DPCB-H)] (5b)
[Pt(bdt)(DPCB-phen)] (6a)
[Pt(dmit)(DPCB-phen) (6b)
556 (3.76)
568 (3.85)
583 (4.03)
604 (4.06)
636
674
646
701
1.94
1.83
1.91
1.77
The data were obtained in CHCl3 at room temperature. The HLG
values were estimated from the absorption edge wavelengths (ledge).
Fig. 8 UV-vis absorption spectra for 6a, 6b and 4b in CHCl3.
ꢀc
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1718 | New J. Chem., 2010, 34, 1713–1722

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[PtCl2(DPCB-phen)] were obtained by ligand displacement of
[PtCl2(cod)] and [PtCl2(SMe2)2] with the corresponding
DPCB-Y ligand, respectively. Other chemicals were obtained
from commercial sources and used as received.
J
PtC = 362 Hz, CRC), 123.6 (s), 123.7 (t, JPC = 11 Hz), 124.5
(q, JFC = 272 Hz), 125.6 (d, JPC = 6 Hz), 127.7 (s), 129.9 (q,
JFC = 32 Hz), 131.7 (s, JPtC = 160 Hz), 133.4 (t, JPC = 4 Hz,
J
PtC = 54 Hz), 135.7 (s), 146.1 (t, JPC = 10 Hz), 153.3 (s), 156.3
(s), 159.2 (s), 171.0 (t, JPC = 32 Hz). 31P{1H} NMR (CD2Cl2,
20 1C): d 169.6 (s, JPtP = 3473 Hz). Anal. calcd for
C70H80F6O2P2Pt: C, 63.48; H, 6.09%. Found: C, 63.28;
H, 6.09%.
Synthesis
[Pt(tolan-X)(DPCB-Y)] (X = OMe, H). A typical procedure
is reported for 2a (X = OMe, Y = H). The complex [Pt(cod)2]
(419 mg, 1.02 mmol) was suspended in hexane (13 mL) at
ꢁ20 1C, and a solution of 1,2-bis(4-methoxyphenyl)ethyne
(tolan-OMe) (243 mg, 1.02 mmol) in Et2O (6 mL) was added
dropwise with stirring. After 1 h, a pale yellow precipitate of
[Pt(tolan-OMe)(cod)] formed in the system was collected by
filtration, washed with hexane (5 mL ꢂ 3), and dried under
vacuum (415 mg, 75%).
1
1b (X = H, Y = OMe). H NMR (CD2Cl2, 20 1C): d 1.50
(s, 18H), 1.64 (s, 36H), 3.71 (s, 6H), 6.45 (d, J = 9.0 Hz, 4H),
6.85 (d, J = 8.7 Hz, 4H), 7.12 (d, J = 1.8 Hz, 4H), 7.14 (s,
2H), 7.64 (s, 4H), 7.67 (dd, J = 7.2 and 1.5 Hz, 4H). 13C{1H}
NMR (CD2Cl2, 20 1C): d 31.7 (s), 33.5 (s), 35.7 (s), 39.4 (s),
55.5 (s), 113.9 (s), 123.2 (s), 123.9 (s, JPtC = 366 Hz, CRC),
124.8 (s), 126.9 (s), 128.3 (s), 129.4 (s), 131.6 (t, JPC = 11 Hz),
131.8 (t, JPC = 4 Hz, JPtC = 52 Hz), 132.3 (s, JPtC = 160 Hz),
146.6 (t, JPC = 9 Hz), 152.7 (s), 156.3 (s), 160.1 (s), 173.1 (dd,
JPC = 32 and 31 Hz). 31P{1H} NMR (CD2Cl2, 20 1C): d 152.6
(s, JPtP = 3480 Hz). Anal. calcd for C68H82O2P2Pt: C, 68.73;
H, 6.96%. Found: C, 68.43; H, 6.97%.
2b (X = H, Y = H). 1H NMR (CD2Cl2, 20 1C): d 1.51
(s, 18H), 1.66 (s, 36H), 6.95 (d, J = 4.5 Hz, 8H), 7.14–7.17
(m, 8H), 7.65 (s, 4H), 7.69 (dd, JHH = 7.8 and 2.7 Hz,
4H). 13C{1H} NMR (CD2Cl2, 20 1C): d 31.7 (s), 33.9 (s),
35.7 (s), 39.4 (s), 123.3 (s), 124.0 (m, JPtC = 365 Hz,
CRC), 127.0 (s), 127.7 (s), 128.3 (s), 128.6 (s), 128.8 (s),
131.5 (t, JPC = 10 Hz), 131.8 (t, JPC = 4 Hz, JPtC = 52 Hz),
131.9 (s, JPtC = 160 Hz), 132.3 (s), 147.6 (t, JPC = 9 Hz),
152.9 (s), 156.2 (s), 172.6 (dd, JPC = 32 and 31 Hz).
31P{1H} NMR (CD2Cl2, 20 1C): d 159.7 (s, JPtP = 3485 Hz).
Anal. calcd for C66H78P2Pt: C, 70.25; H, 6.97%. Found: C,
70.45; H, 6.90%.
A part of the product (124 mg, 0.229 mmol) was dissolved in
CH2Cl2 (3 mL), and solid DPCB (173 mg, 0.229 mmol) was
added in one portion. The mixture was stirred for 2 h at room
temperature, and then concentrated to dryness. The resulting
solid was washed with hexane (2 mL ꢂ 3) and dried under
vacuum to afford deep purple powder of 2a (153 mg, 56%),
which was analytically pure. The product was dissolved in
CH2Cl2 (ca. 0.5 mL), layered with MeOH (2 mL), and allowed
to stand at room temperature to give single crystals suitable
for X-ray diffraction analysis.
Complexes 1a (64%), 1b (60%), 2b (70%), 3a (46%) and 3b
(27%) were similarly prepared and characterized by NMR
spectroscopy and elemental analysis.
1
1a (X = OMe, Y = OMe). H NMR (CD2Cl2, 20 1C): d
1.51 (s, 18H), 1.66 (s, 36H), 3.72 (s, 6H), 3.76 (s, 6H), 6.47 (d,
J = 9.0 Hz, 4H), 6.67 (d, J = 9.0 Hz, 4H), 6.87 (d, J = 9.0 Hz,
4H), 7.61 (d, J = 8.7 Hz, 4H), 7.66 (s, 4H). 13C{1H} NMR
(CD2Cl2, 20 1C): d 31.7 (s), 33.8 (s), 35.7 (s), 39.4 (s),
55.5 (s), 113.6 (s), 113.9 (s), 121.6 (m, JPtC = 353 Hz,
CRC), 123.2 (s), 124.2 (t, JPC = 11 Hz), 125.0 (s), 129.4
3b (X = H, Y = CF3). 1H NMR (CD2Cl2, 20 1C): d 1.53 (s,
18H), 1.68 (s, 36H), 7.02 (d, J = 8.4 Hz, 4H), 7.17–7.25 (m,
10H), 7.69 (s, 4H), 7.74 (dd, J = 7.8 and 2.1 Hz, 4H). 13C{1H}
NMR (CD2Cl2, 20 1C): d 31.6 (s), 34.0 (s), 35.7 (s), 39.4 (s),
(s), 132.6 (s, JPtC = 160 Hz), 133.3 (t, JPC = 3 Hz, JPtC
=
123.6 (s), 124.1 (m, JPtC = 362 Hz, CRC), 124.5 (q, JFC =
54 Hz), 146.4 (t, JPC = 9 Hz), 152.6 (s), 156.2 (s), 158.8 (s),
160.0 (s), 172.8 (dd, JPC = 33 and 31 Hz). 31P{1H} NMR
(CD2Cl2, 20 1C): d 153.0 (s, JPtP = 3458 Hz). Anal. calcd for
C70H86O4P2Pt: C, 67.34; H, 6.94%. Found: C, 67.02;
H, 6.97%.
273 Hz), 125.7 (d, JPC = 4 Hz), 127.4 (s), 127.7 (s), 128.4 (s),
129.9 (q, JFC = 32 Hz), 131.2 (t, JPC = 10 Hz), 131.4 (s, JPtC
= 160 Hz), 131.9 (t, JPC = 4 Hz, JPtC = 51 Hz), 135.6 (s),
146.2 (t, JPC = 10 Hz), 153.4 (s), 156.4 (s), 171.4 (dd, JPC = 32
and 31 Hz). 31P{1H} NMR (CD2Cl2, 20 1C): d 169.5 (s, JPtP
=
1
2a (X = OMe, Y = H). H NMR (CD2Cl2, 20 1C): d 1.48
3495 Hz). Anal. calcd for C68H76F6P2Pt: C, 64.60; H, 6.06%.
Found: C, 64.80; H, 6.05%.
(s, 18H), 1.63 (s, 36H), 3.75 (s, 6H), 6.66 (d, J = 9.0 Hz, 4H),
6.91–6.95 (m, 8H), 7.10–7.15 (m, 2H), 7.60 (d, J = 9.0 Hz,
4H), 7.63 (s, 4H). 13C{1H} NMR (CD2Cl2, 20 1C): d 31.6 (s),
[Pt(tolan-CF3)(DPCB-Y)]. A typical procedure is reported
for 2c (Y = H). The complex [Pt(cod)2] (23 mg, 0.056 mmol)
was dissolved in CH2Cl2 (2 mL) at room temperature, and
1,2-bis(4-trifluoromethylphenyl)ethyne (tolan-CF3) (18 mg,
0.057 mmol) was added with stirring. After 5 min, DPCB
(43 mg, 0.057 mmol) was added, and the mixture was stirred
for additional 2 h. Volatile substances were removed under
reduced pressure, and the residue was washed with hexane
(2 mL ꢂ 3) and dried under vacuum to give 2c as dark red
powder (32 mg, 45%). Complexes 1c (59%) and 3c (30%) were
similarly prepared.
33.9 (s), 35.7 (s), 39.4 (s), 55.5 (s), 113.6 (s), 121.8 (m, JPtC
=
361 Hz, CRC), 123.3 (s), 124.0 (t, JPC = 11 Hz), 127.7 (s),
128.5 (s), 128.7 (s), 132.2 (s, JPtC = 160 Hz), 132.3 (s), 133.4 (t,
JPC = 4 Hz, JPtC = 54 Hz), 147.4 (t, JPC = 9 Hz), 152.8 (s),
156.1 (s), 158.9 (s) 172.2 (dd, JPC = 32 and 31 Hz). 31P{1H}
NMR (CD2Cl2, 20 1C): d 160.0 (s, JPtP = 3460 Hz). Anal.
calcd for C68H82O2P2Pt: C, 68.73; H, 6.96%. Found: C, 68.40;
H, 6.94%.
3a (X = OMe, Y = CF3). 1H NMR (CD2Cl2, 20 1C): d 1.48
(s, 18H), 1.62 (s, 36H), 3.76 (s, 6H), 6.68 (d, J = 8.4 Hz, 4H),
6.97 (d, J = 8.1 Hz, 4H), 7.17 (d, J = 8.1 Hz, 4H), 7.60 (d,
J = 8.7 Hz, 4H), 7.63 (s, 4H). 13C{1H} NMR (CD2Cl2, 20 1C):
d 31.6 (s), 34.0 (s), 35.7 (s), 39.4 (s), 55.5 (s), 113.7 (s), 122.1 (m,
1c (X = CF3, Y = OMe). 1H NMR (CD2Cl2, 20 1C): d 1.53
(s, 18H), 1.66 (s, 36H), 3.74 (s, 6H), 6.49 (d, J = 9.0 Hz, 4H),
6.90 (d, J = 9.0 Hz, 4H), 7.42 (d, J = 8.4 Hz, 4H), 7.68 (s,
ꢀc
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4H), 7.76 (d, J = 7.8 Hz, 4H). 13C{1H} NMR (CD2Cl2, 20 1C):
d 31.7 (s), 33.9 (s), 35.8 (s), 39.4 (s), 55.6 (s), 114.1 (s), 123.5 (s),
124.6 (s), 124.9 (q, JFC = 272 Hz), 124.9 (m, CRC), 125.4 (d,
reduced pressure, the residue was washed with Et2O at ꢁ78 1C
and dried under vacuum. Crystallization of the resulting
compound from a CH2Cl2–Et2O mixed solvent gave 5a as
dark red crystals (38 mg, 72%). Complex 6a was similarly
prepared in 72% yield.
JPC = 3 Hz), 128.3 (q, JFC = 32 Hz), 129.6 (s), 131.5 (t, JPC
=
3 Hz, JPtC = 54 Hz), 131.6 (s, JPtC = 159 Hz), 135.4 (t, JPC
=
11 Hz), 147.2 (t, JPC = 9 Hz), 153.2 (s), 156.5 (s), 160.4 (s) 173.6
(dd, JPC = 33 and 31 Hz). 31P{1H} NMR (CD2Cl2, 20 1C): d
149.8 (s, JPtP = 3522 Hz). Anal. calcd for C70H80F6O2P2Pt: C,
63.48; H, 6.09%. Found: C, 63.84; H, 5.85%.
5a (Y = H). 1H NMR (CD2Cl2, 20 1C): d 1.41 (s, 18H), 1.67
(s, 36H), 6.75 (t, J = 3.2 Hz, 2H), 6.87–6.88 (m, 8H) 7.14 (dd,
J = 4.4 and 4.0 Hz, 2H), 7.42 (t, J = 3.2 Hz, 2H), 7.64 (4H, d,
J = 2.8 Hz). 13C{1H} NMR (CD2Cl2, 20 1C): d 31.6 (s), 35.4
(s), 36.0 (s), 40.2 (s), 122.4 (s), 123.5 (d, JPC = 20 Hz), 124.9
(dd, JPC = 5 Hz), 128.0 (s), 128.6 (s), 129.0 (s), 130.5 (s), 131.1
(s), 144.9 (t, JPC = 6 Hz), 149.3 (dd, JPC = 49 and 32 Hz), 155.4
(s), 158.2 (s), 166.9 (dd, JPC = 68 and 18 Hz). 31P{1H} NMR
(CD2Cl2, 20 1C): d 146.1 (s, JPtP = 3265 Hz). Anal. calcd
for C58H72P2PtS2: C, 63.89; H, 6.66%. Found: C, 63.46;
H, 6.67%.
1
2c (X = CF3, Y = H). H NMR (CD2Cl2, 20 1C): d 1.49
(s, 18H), 1.63 (s, 36H), 6.94–6.99 (m, 8H), 7.13–7.19 (m, 2H),
7.40 (d, J = 8.1 Hz, 4H), 7.64 (s, 4H), 7.73 (d, J = 8.1 Hz,
4H). 13C{1H} NMR (CD2Cl2, 20 1C): d 31.6 (s), 33.9 (s), 35.7
(s), 39.4 (s), 123.5 (s), 124.8 (q, JFC = 272 Hz), 125.4 (m,
CRC), 125.4 (d, JPC = 3 Hz), 127.8 (s), 128.4 (q, JFC
32 Hz), 128.6 (s), 129.2 (s), 131.1 (s, JPtC = 158 Hz), 131.5 (t,
PC = 3 Hz, JPtC = 52 Hz), 131.9 (s), 135.3 (t, JPC = 12 Hz),
148.2 (t, JPC = 10 Hz), 153.3 (s), 156.3 (s), 173.0 (dd, JPC = 33
and 31 Hz). 31P{1H} NMR (CD2Cl2, 20 1C): d 157.2 (s, JPtP
=
1
J
6a (Y = phen): H NMR (CD2Cl2, 20 1C): d 1.50 (s, 18H),
1.75 (s, 36H), 6.17 (d, J = 8.0 Hz, 2H), 6.75 (t, J = 3.2 Hz,
2H), 7.24 (dd, J = 7.6 and 8.0 Hz, 2H), 7.42 (t, J = 3.2 Hz,
2H), 7.63 (dd, J = 7.6 and 8.4 Hz, 2H), 7.78 (s, 4H), 8.54 (d,
J = 8.4 Hz, 2H). 13C{1H} NMR (CD2Cl2, 20 1C): d 31.7 (s),
35.4 (s), 36.1 (s), 40.0 (s), 122.6 (s), 123.7 (d, JPC = 14 Hz),
124.3 (s), 124.4 (s), 124.7 (s), 125.7 (s), 128.4 (s), 128.6 (s),
129.3 (s), 133.2 (t, JPC = 3 Hz), 144.6 (dd, JPC = 57 and
21 Hz), 155.6 (s), 159.2 (s), 168.4 (dd, JPC = 62 and 21 Hz).
31P{1H} NMR (CD2Cl2, 20 1C): d 144.7 (s, JPtP = 3149 Hz).
Anal. calcd for C58H70P2PtS2: C, 64.41; H, 6.48%. Found: C,
63.79; H, 6.35%.
=
3528 Hz). Anal. calcd for C68H76F6P2Pt: C, 64.60; H, 6.06%.
Found: C, 64.55; H, 6.15%.
3c (X = CF3, Y = CF3). 1H NMR (CD2Cl2, 20 1C): d 1.49
(s, 18H), 1.63 (s, 36H), 6.99 (d, J = 8.1 Hz, 4H), 7.21 (d,
J = 8.4 Hz, 4H), 7.44 (d, J = 8.1 Hz, 4H), 7.66 (s, 4H), 7.74
(d, J = 7.8 Hz, 4H). 13C{1H} NMR (CD2Cl2, 20 1C): d 31.6
(s), 34.0 (s), 35.8 (s), 39.4 (s), 123.7 (s), 124.4 (q, JFC = 272 Hz),
124.8 (q, JFC = 272 Hz), 124.8 (m, CRC), 125.5 (d, JPC
=
3 Hz), 125.7 (d, JPC = 3 Hz), 127.8 (s), 128.7 (q, JFC = 32 Hz),
130.3 (q, JFC = 33 Hz), 130.5 (s, JPtC = 159 Hz), 131.5 (t,
J
PC = 4 Hz, JPtC = 50 Hz), 135.0 (t, JPC = 10 Hz), 135.3 (s),
146.7 (t, JPC = 10 Hz), 153.8 (s), 156.5 (s), 171.7 (dd, JPC = 33
and 31 Hz). 31P{1H} NMR (CD2Cl2, 20 1C): d 167.0 (s, JPtP
[Pt(dmit)(DPCB-Y)]. To a 10 ml Schlenk tube were added
[PtCl2(DPCB-H)] (50 mg, 0.049 mmol), [NEt4]2[Zn(dmit)2]
(19 mg, 0.027 mmol), and CH2Cl2 (2.5 mL). The solution
was stirred overnight at room temperature, and washed with
brine (2 mL ꢂ 3) and H2O (2 mL ꢂ 1). The organic phase was
dried over Na2SO4 and concentrated to dryness under
vacuum. The residue was washed with acetone to afford 5b
as a dark green powder (52 mg, 92%). Complex 6b was
similarly synthesized in 77% yield.
=
3541 Hz). Anal. calcd for C70H74F12P2Pt: C, 60.04; H, 5.33%.
Found: C, 59.64; H, 5.56%.
[Pt(tolan-H)(dppe)]. To a solution of [Pt(tolan)(cod)] (33 mg,
0.069 mmol) in CH2Cl2 (2 mL) was added 1,2-bis(diphenyl-
phosphanyl)ethane (dppe) (28 mg, 0.070 mmol) at ꢁ30 1C with
stirring. After 1 h, the solvent was removed under reduced
pressure. The residue was dissolved in CH2Cl2 (ca. 0.5 mL),
layered with Et2O (2 mL), and allowed to stand at 0 1C,
giving pale yellow crystals of the title compound (42 mg,
5b (Y = H): 1H NMR (CD2Cl2, 20 1C): d 1.46 (s, 18H), 1.69
(s, 36H), 6.95–6.99 (m, 8H), 7.24 (dd, J = 4.4 and 4.0 Hz,
2H), 7.74 (d, J = 3.2 Hz, 4H). 13C{1H} NMR (CD2Cl2,
20 1C): d 31.5 (s), 35.5 (s), 36.0 (s), 40.2 (s), 122.1 (d, JPC
=
1
79%). H NMR (CD2Cl2, 20 1C): d 2.38 (dt, J = 14.4 and
40 Hz), 125.2 (s), 128.2 (s), 129.1 (s), 130.5 (s), 131.0 (s),
136.2 (t, JPC = 9 Hz), 149.9 (t, JPC = 61 Hz), 156.0 (s), 158.1
(s), 166.2 (t, JPC = 37 Hz), 222.3 (s). 31P{1H} NMR (CD2Cl2,
20 1C): d 140.4 (s, JPtP = 3414 Hz). Anal. calcd for
C55H68P2PtS5: C, 57.62; H, 5.98%. Found: C, 57.55;
H, 5.99%.
9.6 Hz, 4H), 7.14 (d, J = 7.2 Hz, 2H), 7.20 (dd, J = 6.9 and
7.2 Hz, 4H), 7.32–7.40 (m, 4H), 7.64 (dd, J = 8.4 and 1.5 Hz,
4H), 7.76–7.83 (m, 8H). 13C{1H} NMR (CD2Cl2, 20 1C):
d 31.1 (dd, JPC = 10 Hz, JPtC = 50 Hz), 126.4 (s), 128.5 (s),
128.8 (t, JPC = 7 Hz), 130.4 (s), 130.8 (t, JPC = 3 Hz,
JPtC = 43 Hz), 133.3 (t, JPC = 8 Hz, JPtC = 25 Hz), 135.3
1
6b (Y = phen). H NMR (CD2Cl2, 20 1C): d 1.50 (s, 18H),
(t, JPC = 22 Hz), 135.8 (t, JPC = 9 Hz), 135.6 (m, JPtC =
313 Hz, CRC). 31P{1H} NMR (CD2Cl2, 20 1C): d 49.6
(s, JPtC = 3110 Hz).
1.73 (s, 36H), 6.25 (d, J = 8.0 Hz, 2H), 7.24 (dd, J = 7.6 and
8.0 Hz, 2H), 7.62 (dd, J = 7.6 and 8.4 Hz, 2H), 7.81 (d,
J = 4.0 Hz, 4H), 8.54 (d, J = 8.4 Hz, 2H). 13C{1H} NMR
(CD2Cl2, 20 1C): d 31.6 (s), 35.4 (s), 36.1 (s), 40.0 (s), 122.4
(d, JPC = 40 Hz), 124.4 (s), 124.5 (s), 124.8 (s), 125.7 (s), 128.8
(s), 129.9 (s), 133.5 (t, JPC = 6 Hz), 144.0 (t, JPC = 56 Hz),
156.2 (s), 159.2 (s), 167.7 (dd, JPC = 48 and 50 Hz), 222.5 (s).
31P{1H} NMR (CD2Cl2, 20 1C): d 138.0 (s, JPtP = 3350 Hz).
Anal. calcd for C55H66P2PtS5: C, 57.72; H, 5.81%. Found: C,
57.66; H, 5.85%.
[Pt(bdt)(DPCB-Y)]. To a solution of [PtCl2(DPCB-H)]
(50 mg, 0.049 mmol) and 1,2-benzenedithiol (10 mg,
0.074 mmol) in THF (2.5 mL) was added dropwise DBU
(450 mg, 2.94 mmol) at ꢁ78 1C. The reaction mixture was
gradually warmed to room temperature and stirred for 2 h to
give a dark green solution. After removal of volatiles under
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Table 8 Crystallographic data for 2a, 2c, 3b, 5a, [Pt(tolan-H)(dppe)], and [PtCl2(DPCB-H)]
Compound
2a
2c
3b
5a
[Pt(tolan-H)(dppe)] [PtCl2(DPCB-H)]ꢃMe2CO
Formula
Formula weight
Space group
a/A
b/A
c/A
a (1)
C68H82O2P2Pt
1188.37
C68H76F6P2Pt
1264.32
C68H76F6P2Pt
1264.32
C58H72P2Pt1S2
1090.31
Pnca
15.746(2)
16.859(2)
19.937
90.00
90.00
90.00
5292.3(12)
4
2.826
C40H34P2Pt
771.70
C52H68Cl2P2PtꢃC3H6O
1079.07
P21/c
ꢀ
P1
ꢀ
P1
ꢀ
P1
ꢀ
P1
9.264(2)
16.459(4)
20.290(5)
97.529(5)
91.894(5)
91.270(5)
3064.2(12)
2
9.164(3)
16.791(5)
21.506(7)
70.738(8)
82.039(12)
87.536(12)
3093.9(17)
2
2.376
173(2)
25002
13521
9.477(4)
11.489(5)
29.035(13)
86.858(15)
88.386(15)
80.386(14)
3112(2)
2
2.362
173(2)
25137
13606
10.8407(10)
17.0681(18)
19.0121(17)
79.591(6)
73.981(6)
85.655(6)
3324.3(6)
4
4.344
295(2)
32907
14900
19.008(9)
14.477(4)
19.693(6)
90.00
111.193(4)
90.00
5053(3)
4
2.983
203(2)
47646
14549 (Rint = 0.0587)
b (1)
g (1)
V/A3
Z
m(Mo-Ka)/mmꢁ1
T/K
Reflections collected 24595
2.384
173(2)
173(2)
40678
6007
Unique reflections
13360
(Rint = 0.0311) (Rint = 0.0375) (Rint = 0.0538) (Rint = 0.0498) (Rint = 0.0351)
1.040
GOF
1.078
1.088
0.627
1.086
1.056
R indices
(I > 2s(I))
R indices
(All data)
R1 = 0.0354
wR2 = 0.0831
R1 = 0.0444
wR2 = 0.0886
R1 = 0.0454
wR2 = 0.0964
R1 = 0.0530
wR2 = 0.1012
R1 = 0.0554
wR2 = 0.1253
R1 = 0.0707
wR2 = 0.1371
R1 = 0.0232
wR2 = 0.0780
R1 = 0.0287
wR2 = 0.0848
R1 = 0.0564
wR2 = 0.1292
R1 = 0.0833
wR2 = 0.1411
R1 = 0.0485
wR2 = 0.1454
R1 = 0.0524
wR2 = 0.1499
The space group ‘‘Pnca’’ for 5a is a non-standard setting of space group ‘‘Pbcn’’.
X-Ray diffraction analysis
Notes and references
The X-ray diffraction studies were performed on a Rigaku
Mercury CCD diffractometer with graphite-monochromated
Mo-Ka radiation (l = 0.71070 A). The intensity data were
collected at 173, 203, or 295 K, and corrected for Lorentz and
polarization effects and absorption (numerical). The structure
was solved by direct methods (SHELXS-97) and refined on
F2 for all reflections (SHELXL-97).30 The crystallographic
data and the summary of solution and refinement are
listed in Table 8. CCDC reference numbers 735887 and
765285–765289. For crystallographic data in CIF or other
electronic format see DOI: 10.1039/c0nj00118j
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Acknowledgements
This work was supported by Grant-in-Aids for Scientific
Research on Priority Areas ‘‘Synergy of Elements’’ and
‘‘Molecular Theory for Real Systems’’ from MEXT, Japan.
13 The X-ray structure of [Pt(tolan-H)(DPCB-H)] was determined in
this study.
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1722 | New J. Chem., 2010, 34, 1713–1722