Cis and trans influences on [Pt(SRF)(triphos)]+ complexes (SRF = polyfluorobenzothiolate)

Article abstract of DOI:10.1039/c4nj01686f

Platinum(II) derivatives of the tridentate ligand Ph₂PCH₂CH₂P(Ph)CH₂CH₂PPh₂ (triphos), including [Pt(SRF)(triphos)](CF₃SO₃) R_F = C₆F₄CF₃-4 1, C₆F₅ 2, C₆HF₄-4 3, C₆H₄CF₃-4 4, C₆H₃F₂-2,4 5, C₆H₄F-2 6, C₆H₄F-4 7 and C₆H₅ 8, have been prepared and characterised. 1H, 19F and 31P solution NMR has been used to evaluate the cis and trans influences of the fluorinated and non-fluorinated benzothiolate ligands, particularly through the cis and trans ¹J_Pt-P values. The crystal and molecular structures of [Pt(SC₆F₄CF₃-4)(triphos)](CF₃SO₃) 1, with a perfluorinated thiolate ligand, [Pt(SC₆HF₄-4)(triphos)](CF₃SO₃) 3, having a fluorinated thiolate, and [Pt(SC₆H₅)(triphos)](CF₃SO₃) 8, bearing a non-fluorinated moiety, are discussed as examples of extreme electronegativities.

Full text of DOI:10.1039/c4nj01686f

NJC
PAPER
cis and trans influences on [Pt(SRF)(triphos)]+
complexes (SRF = polyfluorobenzothiolate)†
Cite this: New J. Chem., 2015,
39, 631
Ruy Cervantes,‡a Jorge Tiburciob and Hugo Torrens*a
Platinum(II) derivatives of the tridentate ligand Ph2PCH2CH2P(Ph)CH2CH2PPh2 (triphos), including
[Pt(SRF)(triphos)](CF3SO3) RF = C6F4CF3-4 1, C6F5 2, C6HF4-4 3, C6H4CF3-4 4, C6H3F2-2,4 5, C6H4F-2 6,
C6H4F-4 7 and C6H5 8, have been prepared and characterised. 1H, 19F and 31P solution NMR has been
used to evaluate the cis and trans influences of the fluorinated and non-fluorinated benzothiolate
Received (in Porto Alegre, Brazil)
30th September 2014,
Accepted 31st October 2014
1
ligands, particularly through the cis and trans JPt–P values. The crystal and molecular structures of
[Pt(SC6F4CF3-4)(triphos)](CF3SO3) 1, with a perfluorinated thiolate ligand, [Pt(SC6HF4-4)(triphos)](CF3SO3)
3, having a fluorinated thiolate, and [Pt(SC6H5)(triphos)](CF3SO3) 8, bearing a non-fluorinated moiety, are
discussed as examples of extreme electronegativities.
DOI: 10.1039/c4nj01686f
www.rsc.org/njc
To that end, we have examined the cis and trans influences
1. Introduction
of a series of fluorinated benzothiolate ligands (SRF)ꢀ in
A large number of studies focusing on trans and cis influences cationic complexes with the general formula [Pt(SRF)(triphos)]+.
have been published from when they were first observed1 up to PhP(CH2CH2PPh)2 (triphos) has been widely studied12 and is
the present day.2 trans and cis influences have long been used very useful for heteronuclear NMR studies because, once it is
to rationalise bond strengths and bond lengths and therefore co-coordinated to platinum, this tridentate ligand allows the
reactivity,3 but their scope has been extended to include simultaneous observation of three 31P NMR coupling constants
theoretical implications,4 the study of a growing number of (1JPt–P , 1JPt–P and 2JP
).13 Furthermore, in square planar
trans–Pcis
trans
cis
ligands,5 their role in influencing the stability of geometrical compounds, the tridentate ligand leaves just a single free and
isomers,6 and the particular chemical behaviours of specific unique place of coordination to be occupied by the fluoro-
processes, such as bond and molecule activation7 or ligand thiolated ligands.
exchange.8 On the other hand, because the trans and cis
This work reports the synthesis of a new series of compounds
influences also play significant roles in the chemistry of main with the general formula [Pt(SRF)(triphos)](CF3SO3), RF
group9 and rare earth elements,10 the general validity of these C6F4CF3-4 1, C6F5 2, C6HF4-4 3, C6H4CF3-4 4, C6H3F2-2,4, 5,
aspects is now well documented. C6H4F-2 6, C6H4F-4 7 and C6H5 8. The results show that there
=
We have long-standing interest in transition metal deriva- is a strengthening of the platinum–phosphorous bond trans to
tives bearing both phosphines and fluorinated benzothiolate the thiolate as the number of fluorine atoms on this ligand
ligands.11 In particular, we are interested in the possible increases.
modulation of molecular properties induced by variations of
the fluorination degree of benzothiolate ligands attached to the
metal centre. If such a modulation is to be rationally achieved
to some degree, a measure of the relative influence of each
ligand is required. In this case, the modulated properties are
2. Experimental
2.1. General
the trans and cis influences.
Solvents were dried using established procedures and were
distilled under nitrogen gas immediately prior to use.25 Thin-
layer chromatography (TLC) (Merck, silica gel 60 F254 and
neutral aluminium oxide 60 F254) was used to monitor the
progress of the reactions being studied using hexane/ethyl
acetate (9 : 1) as the eluent. All of the reactions were carried
out under inert conditions with dry oxygen-free nitrogen gas
using Schlenk techniques. Melting points were obtained using
a Fisher-Johns melting point apparatus. Infrared spectra were
recorded as KBr pellets on a Perkin Elmer Model 1605 Fourier
a
´
´
´
Facultad de Quımica, Universidad Nacional Autonoma de Mexico, 04510,
´
Mexico D.F., Mexico. E-mail: torrens@unam.mx
b
´
´
Departamento de Quımica, Cinvestav, Av. Instituto Politecnico Nacional 2508,
´
San Pedro Zacatenco, 07360, Mexico D.F., Mexico
† Electronic supplementary information (ESI) available. CCDC 1025112 (1),
1026048 (3) and 1025113 (8). For ESI and crystallographic data in CIF or other
electronic format see DOI: 10.1039/c4nj01686f
´
´
‡ Present address: Departamento de Quımica, Cinvestav, Av. Instituto Politecnico
´
Nacional 2508, San Pedro Zacatenco, 07360, Mexico D.F., Mexico.
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
New J. Chem., 2015, 39, 631--638 | 631

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spectrometer in the range of 4000 to 400 cmꢀ1. Elemental CF3, JF–F = 21.1 Hz); NMR H (300 MHz, CDCl3): 2.1–3.9 (m, 8H,
analyses were determined using a Fisons EA-1108 instrument. CH2–CH2 triphos), 7.2–8.1 (m, 25H, Ph triphos).
Nuclear magnetic resonance spectra, 1H, 13C, 19F{1H} and
4
1
[Pt(SC6F5)(triphos)](CF3SO3) 2. White crystalline solid; 98.3%
yield; mp: d-195 1C; Anal. calcd for C41H33O3F8S2P3Pt C: 45.68,
31P{1H}, were recorded on a Varian Unity INOVA-300 spectro-
meter. Chemical shifts are in ppm relative to internal TMS d = 0
H: 3.08, S: 5.94, found C: 45.7, H: 3.0, S: 5.9; IR (KBr): n = 3055,
(1H, 13C) and CFCl3 (for 19F) and H3PO4 (for 31P) at 0 ppm as
2918, 1625, 1573, 1508, 1478, 1274, 1151, 1030, 857 cmꢀ1
;
external references. J values are given in Hz. The following
abbreviations were used for the multiplicities: s = singlet,
bs = broad singlet, d = doublet, dd = doublets of doublets,
t = triplet, and m = multiple. Positive-ion fast atom bombardment
mass spectrometry (FAB+-MS) spectra were recorded on a Jeol
JMS-SX102A mass spectrometer operated at an acceleration
voltage of 10 kV. Samples were desorbed from a 3-nitrobenzyl
alcohol matrix using 3 keV xenon atoms. Mass measurements in
FAB are performed at a resolution of 3000 using magnetic field
scans and the matrix ions as the reference material. Tl(CH3COO),
C6H5SH, C6F5SH and K2[PtCl4] were supplied by the Aldrich Co.;
Ag(CF3SO3), Ph2PC2H4P(Ph)C2H4PPh2 and C6HF4SH were from
Strem Chemicals; and 4-C6F4(CF3)SH, 4-C6H4FSH, 4-C6H4(CF3)SH
and 2,4-C6H3F2SH were acquired from Oakwood Products Inc. All
of these chemicals were used without further purification. Tl(SRF)
(RF = C6F4(CF3)-4, C6F5, C6HF4-4, C6H4(CF3)-4, C6H3F2-2,4, C6H4F-2,
C6H4F-4 and C6H5) salts were prepared by reacting stoichiometric
quantities of the corresponding reactants (Tl(CH3COO) + RFSH)
in water under vigorous stirring, filtering the precipitate and
recrystallising the precipitate from acetone. [PtCl(triphos)]Cl
(ref. 26) and [Pt(CF3SO3)(triphos)] (CF3SO3) (ref. 27) were
prepared by published methods.
MS-FAB+ (m/z): 928 [M]+ (100), 409 (M+-SRF-(PPh2)2-(CH2)2).
NMR 31P{1H} (121.3 MHz, CDCl3): 88.9 (d, Ptrans
,
1JP
=
trans–Pt
2466 Hz), 41.2 (d, Pcis
,
1JP
= 2551 Hz; 2JP
= 4.0 Hz).
trans–Pcis
cis–Pt
NMR 19F{1H} (282 MHz, CDCl3): ꢀ78.67 (s, 3F, CF3SO3),
ꢀ132.34 (m, 2F, o-F), ꢀ163.1 (m, 2F, m-F), ꢀ159.7 (m, 1F,
p-F). NMR 1H (300 MHz, CDCl3): 2.1–3.9 (m, 8H, CH2–CH2
triphos), 7.2–8.1 (m, 25H, Ph triphos).
[Pt(SC6HF4-4)(triphos)](CF3SO3) 3. White crystalline solid,
74.5% yield, mp: 244–245 1C. Anal. calcd for C41H34O3S2F7P3Pt
C: 46.0, H: 3.3, S: 6.1. Found C: 46.5, H: 3.2, S: 6.0. IR (KBr):
n = 3055, 2920, 1625, 1482, 1436, 1262, 1151, 1030, 910 cmꢀ1
;
MS-FAB+ (m/z): 910 [M]+ (100). NMR 31P{1H} (121.3 MHz,
1
1
CDCl3): 89.0 (d, Ptrans, JP
= 2465 Hz), 40.1 (d, Pcis, JP
cis–Pt
trans–Pt
= 2550 Hz; 2JP
= 4.1 Hz). NMR 19F (282 MHz, CDCl3):
trans–Pcis
ꢀ78.77 (s, 3F, CF3SO3), ꢀ132.9 (m, 2F, m-F), ꢀ140.4 (m, 2F, o-F).
1
NMR H (300 MHz, CDCl3): 6.22 (tt, 1H p-H), 2.1–3.9 (m, 8H,
CH2–CH2 triphos), 7.2–8.1 (m, 25H, Ph triphos).
[Pt(SC6H4(CF3)-4)(triphos)](CF3SO3) 4. Yellow crystalline solid,
62.01% yield, mp: 90–91 1C. Anal. calcd for C42H37O3S2F6P3Pt, C:
47.7, H: 3.53, S: 6.0. Found C: 47.8, H: 3.5, S: 6.1. IR (KBr):
n = 3054, 2920, 1598, 1436, 1323, 1262, 1154, 1102, 1029, 831 cmꢀ1
;
Caution: Tl(I) salts are known to be extremely toxic. All
procedures were conducted in the fume cupboard and the
collected Tl(I) halide was immediately oxidized with concen-
trated HNO3.
MS-FAB+ (m/z): 907 [M]+ (100). NMR 31P{1H} (121.3 MHz, CDCl3):
d = 89.1 (d, Ptrans, 1JP –Pt = 2370 Hz), 41.0 (d, Pcis, 1JP –Pt = 2566 Hz;
trans
cis
2JP
= 4.4 Hz). NMR 19F (282 MHz, CDCl3): d = ꢀ78.66 (s, 3F,
trans–Pcis
CF3SO3), ꢀ62.20 (s, 3F, CF3). NMR 1H (300 MHz, CDCl3): d = 6.84
3
(d, 2H, o-H), 6.6 (d, 2H, m-H, JH–H = 8.1 Hz), 2.1–3.9 (m, 8H,
2.2. Synthesis
CH2–CH2 triphos), 7.2–8.1 (m, 25H, Ph triphos).
Preparation of compounds 1 to 8. All of the reactions were
carried out using stoichiometric quantities of the reactants,
and because all of the preparations were similar, only a typical
procedure is described below. In a 50 mL round bottom flask,
one equivalent of the corresponding thallium salt, Tl(SRF)
(ca. 45.3 mg, 0.1 mmol for R = C6F4CF3) in 10 mL of dichloro-
methane and a solution of one equivalent of [Pt(CF3SO3)-
(triphos)](CF3SO3) (ca. 103.0 mg, 0.1 mmol) in 25 mL of
dichloromethane were mixed under vigorous stirring. After
24 h, the yellow solution was filtered off to obtain white TlCl
solid. The clear yellow solution was evaporated over a period of
ca. 24 h to obtain yellow crystalline solids formulated as
[Pt(SRF)(triphos)](CF3SO3).
[Pt(SC6H3F2-2,4)(triphos)](CF3SO3) 5. Yellow crystalline solid,
82.45% yield, mp: 108–109 1C. Anal. calcd for C41H36O3S2F5P3Pt,
C: 48.9, H: 3.54, S: 6.26. Found C: 49.0, H: 3.7, S: 6.4. IR (KBr):
n = 3053, 2916, 1587, 1476, 1436, 1260, 1151, 1029, 961 cmꢀ1
.
MS-FAB+ (m/z): 874 [M]+ (100). NMR 31P{1H} (121.3 MHz, CDCl3):
d = 88.1 (d, Ptrans, 1JP –Pt = 2354 Hz), 41.4 (d, Pcis, 1JP –Pt = 2599 Hz;
trans
cis
2JP
= 4.9 Hz). NMR 19F (282 MHz, CDCl3): d = ꢀ78.75 (s, 3F,
trans–Pcis
CF3SO3), ꢀ100.42 (m, 1F, o-F), ꢀ114.69 (m, 1F, p-F). NMR 1H
(300 MHz, CDCl3): d = 6.84 (m, 1H, H-3), 6.1 (m, 1H, H-5), 5.9
(m, 1H, H-6), 2.1–3.9 (m, 8H, CH2–CH2 triphos), 7.2–8.1 (m, 25H,
Ph triphos).
[Pt(SC6H4F-2)(triphos)](CF3SO3) 6. Yellow crystalline solid,
[Pt(SC6F4CF3-4)(triphos)](CF3SO3) 1. White crystalline solid; 75.25% yield, mp: d-198 1C. Anal. calcd for C41H37O3S2F4P3Pt,
95.7% yield; mp: 110–111 1C; Anal. calcd for C42H33O3F10S2P3Pt: C: 48.9, H: 3.7, S: 6.3. Found C: 49.0, H: 3.7, S: 6.4. IR(KBr):
C: 44.7, H: 2.94, S: 5.68, found C: 44.7, H: 2.9, S: 5.7; IR (KBr): n =3051, 2917, 1571, 1467, 1436, 1278, 1255, 1221, 1151, 1106,
n = 3056, 2920, 1641, 1473, 1437, 1324, 1260, 1141, 1029, 972 cmꢀ1
;
1027, 998, 732, 750, 722, 706, 693, 636, 519 cmꢀ1. MS-FAB+
MS-FAB+ (m/z): 978 [M]+ (100); NMR 31P{1H} (121.3 MHz, CDCl3): (m/z): 856 [M]+ (100), 407 (M+-SRF-(PPh2)2-(CH2)2). NMR 31P{1H}
1
1
89.9 (d, Ptrans, JP
= 2524 Hz), 40.0 (d, Pcis, JP
= 2519 Hz, (121.3 MHz, CDCl3): d = 86.5 (d, Ptrans, 1JP –Pt = 2354 Hz), 39.7
trans–Pt
cis–Pt
trans
2JP
= 2.9 Hz); NMR 19F{1H} (282 MHz, CDCl3): ꢀ82.9 (s, 3F, (d, Pcis
,
1JP
= 2591 Hz; 2JP
= 4.7 Hz). NMR 19F (282
trans–Pcis
cis–Pt
trans–Pcis
CF3SO3), ꢀ136.30 (m, 2F, o-F), ꢀ147.28 (m, 2F, m-F), ꢀ60.4 (t, 3F, MHz, CDCl3): d = ꢀ82.0 (s, 3F, CF3SO3), ꢀ108.32 (m, 1F, o-F).
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NMR 1H (300 MHz, CDCl3): d = 6.9 (m, 1H, H-3), 6.5 (m, 1H, H- b = 96.02(3)1, V = 4201.8(14) Å3, T = 293(2) K, space group P21/n, Z
4), 6.2 (m, 1H, H-6), 6.34 (m, 1H, H-5), 2.1–3.9 (m, 8H, CH2–CH2 = 4, m(MoKa) = 3.622 mmꢀ1, 16 857 reflections measured, 5642
triphos), 7.2–8.1 (m, 25H, Ph triphos).
independent reflections (Rint = 0.0950). The final R1 values were
0.0724 (I 4 2s(I)). The final wR(F2) values were 0.1729 (I 4 2s(I)).
The final R1 values were 0.1537 (all data). The final wR(F2) values
were 0.2359 (all data). The goodness of fit on F2 was 1.037. CCDC
1026048.
Crystal structure data for [Pt(SC6H5)((C6H5)2PC2H4P(C6H5)-
C2H4P(C6H5)2)](CF3SO3) 8. C41H38F3O3P3PtS2, M = 987.83,
monoclinic, a = 10.2751(3) Å, b = 19.9018(7) Å, c = 19.3686(8) Å,
b = 93.7440(10)1, V = 3952.3(2) Å3, T = 293(2) K, space group
P21/n, Z = 4, m(MoKa) = 3.830 mmꢀ1, 13 735 reflections
measured, 6381 independent reflections (Rint = 0.0790). The
final R1 values were 0.0660 (I 4 2s(I)). The final wR(F2) values
were 0.1774 (I 4 2s(I)). The final R1 values were 0.1106
(all data). The final wR(F2) values were 0.2267 (all data). The
goodness of fit on F2 was 1.066. CCDC 1025113.
[Pt(SC6H4F-4)(triphos)](CF3SO3) 7. Yellow crystalline solid,
89.97% yield, mp: 105–108 1C. Anal. calcd for C41H37O3S2F4P3Pt,
C: 48.9, H: 3.7, S: 6.3. Found C: 49.0, H: 3.7, S: 6.4. IR (KBr):
n = 3053, 2917, 1629, 1584, 1481, 1436, 1263, 1151, 1029, 829 cmꢀ1
.
MS-FAB+ (m/z): 856 [M]+ (100), 729 [M]+-SRF (20). NMR 31P{1H}
1
(121.3 MHz, CDCl3): d = 87.7 (d, Ptrans, JP
= 2313 Hz), 41.8
trans–Pt
1
2
(d, Pcis, JP
= 2613 Hz; JP
= 5.3 Hz). NMR 19F (282 MHz,
cis–Pt
trans–Pcis
1
CDCl3): d = ꢀ82.0 (s, 3F, CF3SO3), ꢀ108.3 (m, 1F, p-F). NMR H
(300 MHz, CDCl3): d = 6.73 (m, 2H, o-H), 6.12 (m, 2H, m-H), 2.1–3.9
(m, 8H, CH2–CH2 triphos), 7.2–8.1 (m, 25H, Ph triphos).
[Pt(SC6H5)(triphos)](CF3SO3) 8. Yellow crystalline solid, 97.37%
yield, mp: 234–235 1C. Anal. Calcd for C41H38O3S2P3F3Pt, C: 49.8,
H: 3.87, S: 6.49. Found C: 49.8, H: 3.9, S: 6.5. IR(KBr): n = 3052,
2922, 1575, 1471, 1435, 1271, 1147, 1029 cmꢀ1. MS-FAB+ (m/z): 838
[M]+ (100), 729 [M]+-SRF (20). NMR 31P{1H} (121.3 MHz, CDCl3):
3. Results and discussion
3.1. Synthesis of Pt(II) complexes 1–8
d = 87.5 (d, Ptrans
,
1JP
= 2306 Hz), 41.6 (d, Pcis, 1JP
=
cis–Pt
trans–Pt
2609 Hz; 2JP
= 5.2 Hz). NMR 19F (282 MHz, CDCl3):
trans–Pcis
1
[Pt(SRF)(triphos)](CF3SO3) square planar thiolate platinum(II)
complexes 1 to 8 (triphos = PhP(CH2CH2PPh2)2; RF = C6F4CF3-4 1,
C6F5 2, C6HF4-4 3, C6H4CF3-4 4, C6H4F2-2,4 5, C6H4F-2 6, C6H4F-4 7
and C6H5 8) were synthesized by metathesis reactions, in a 1 : 1
stoichiometry, between [Pt(CF3SO3)(triphos)](CF3SO3) and the
corresponding thallium thiolate salts, Tl(SRF). They were all iso-
lated as white or yellow solids, which were relatively soluble in
acetone, acetonitrile and dimethylsulfoxide. Compounds 1–8 are
inert to oxidation in an open atmosphere over a period of weeks.
1H, 19F and 31P NMR, FAB+ mass spectrometry, elemental
analyses and vibrational spectra described in the experimental
section have been used to characterise the prepared complexes.
d = ꢀ78.78 (s, 3F, CF3SO3). NMR H (300 MHz, CDCl3): d = 6.80
(m, 2H, o-H), 6.59 (m, 1H, p-H), 6.46 (m, 2H, m-H), 2.1–3.2 (m, 8H,
CH2–CH2 triphos), 7.3–8.1 (m, 25H, Ph triphos).
2.3. X-Ray crystal structure determination
Suitable crystals for X-ray diffraction analyses of compounds 1,
3 and 8 were grown by slow (multiday) solvent evaporation
of a concentrated acetone solution at room temperature
(293–298 K). Crystals were mounted on a glass fiber. A full
hemisphere of data was collected with 30 s frames using an
Enraf-Nonius Kappa diffractometer fitted with a CCD based
detector using MoKa radiation (0.71073 Å). Diffraction data and
unit-cell parameters were consistent with the assigned space
groups. The structures were solved by direct methods, completed
by subsequent Fourier syntheses and refined with full-matrix
least-squares methods against |F2| data. All non-hydrogen atoms
3.2. Solid-state molecular structures of [Pt(SC6F4CF3-4)-
(triphos)][OTf] 1, [Pt(SC6HF4-4)(triphos)][OTf] 3 and
[Pt(SC6H5)(triphos)][OTf] 8
were refined anisotropically. All hydrogen atoms were treated Moderate-quality crystals for X-ray diffraction analysis of
as idealized contributions. Scattering factors and anomalous complexes [Pt(SC6F4CF3-4)(triphos)](CF3SO3) 1, [Pt(SC6HF4-4)-
dispersion coefficients are contained in the SHELXTL 5.03 (triphos)](CF3SO3) 3 and [Pt(SC6H5)(triphos)](CF3SO3) 8 were
program library.28 Ball-and-stick and space-filling diagrams were obtained by slow evaporation of concentrated acetone solutions
prepared using DIAMOND.29
at room temperature (293–298 K). The molecular structure in
Crystal structure data for [Pt(SC6F4CF3-4)((C6H5)2PC2H4- the solid state of compounds 1, 3 and 8 with their respective
P(C6H5)C2H4P(C6H5)2)](CF3SO3) 1. C42H33F10O3P3PtS2, M = 1127.80, numbering schemes is depicted in Fig. 1 to 3. Selected bond
triclinic, a = 11.1223(4) Å, b = 13.6579(6) Å, c = 16.7386(7) Å, lengths (Å) and angles (1) are summarized in Table 1.
a = 67.229(3)1, b = 81.640(2)1, g = 71.075(2)1, V = 2217.22(16) Å3,
For the three molecular structures, platinum(II) lies at the
T = 293(2) K, space group P1, Z = 2, m(MoKa) = 3.447 mmꢀ1, 11281 centre of a distorted square-planar geometry with the triphos
reflections measured, 6966 independent reflections (Rint = 0.0381). ligand coordinated in a tridentate fashion forming two five-
The final R1 values were 0.0866 (I 4 2s(I)). The final wR(F2) values membered rings. All platinum–phosphorous bond lengths and
were 0.2318 (I 4 2s(I)). The final R1 values were 0.1128 (all data). The angles are in agreement with previously reported values.14–16
final wR(F2) values were 0.2972 (all data). The goodness of fit on F2 The Pt1–P2 bond is shorter than the two mutually trans
%
was 1.335. CCDC 1025112.
platinum–phosphorous bonds due to the double chelate effect,
Crystal structure data for [Pt(SC6HF4-4)((C6H5)2PC2H4- in agreement with previously reported chloride complexes
P(C6H5)C2H4P(C6H5)2)](CF3SO3) 3. C41H34F7O3P3PtS2, M = 1059.80, [PtCl(triphos)]X (X = Clꢀ or CuCl2ꢀ).13a The thiolate ligand,
monoclinic, a = 10.188(2) Å, b = 19.711(4) Å, c = 21.039(4) Å, SRFꢀ, occupies the platinum fourth coordination site with the
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2015
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Table 1 Selected bond lengths (Å) and angles (1) for compounds 1, 3 and 8
1
3
8
Bond length (Å)
Pt1–S1
Pt1–P1
Pt1–P2
Pt1–P3
2.354(3)
2.325(4)
2.239(3)
2.292(4)
2.343(5)
2.313(5)
2.234(4)
2.308(4)
2.349(6)
2.295(3)
2.237(3)
2.331(3)
Angles (1)
P1–Pt1–S1
P1–Pt1–P2
P2–Pt1–P3
P3–Pt1–S1
P2–Pt1–S1
Pt1–S1–C1
102.9(1)
84.4(1)
82.6(1)
90.2(2)
172.7(1)
109(1)
104.3(2)
83.4(2)
83.9(2)
88.8(2)
172.1(1)
115(1)
88.0(2)
83.9(1)
83.9(1)
105.1(2)
168.6(2)
88.0(2)
Fig. 1 Ball and stick and space-filling representations with the numbering
scheme of the molecular structure of [Pt(SC6F4CF3-4)(triphos)](CF3SO3) 1
determined by single crystal X-ray diffraction. Pt = gray, P = pink, S = yellow,
C = black, F = green, H = white. The counterion has been omitted for clarity.
of 3.6 Å between centroids of both rings, which is not observed
in the non-fluorinated complex 8 (vide infra).
[Pt(SC6HF4-4)(triphos)][OTf] 3. The analyzed crystal belongs
to the monoclinic space group P21/n. The asymmetric unit
consists of a complete platinum complex and a trifluoromethane-
sulfonate anion. The SC6F4H-4 thiolate ring also forms an
aromatic interaction with one of the electron-rich phenyl rings
of the triphos ligand with an interplanar distance of 3.7 Å, slightly
larger than the one observed for the extremely electron-poor
SC6F5CF3-4 thiolate in complex 1.
Fig. 2 Ball and stick and space-filling representations with the numbering
scheme of the molecular structure of [Pt(SC6HF4-4)(triphos)](CF3SO3)
3 determined by single crystal X-ray diffraction. Pt = gray, P = pink,
S = yellow, C = black, F = green, H = white. The counterion has been
omitted for clarity.
[Pt(SC6H5)(triphos)][OTf] 8. Isolated crystals belong to the
monoclinic space group P21/n. A complete platinum complex
and a trifluoromethanesulfonate anion are present in the
asymmetric unit. The carbon atoms on the thiolate phenyl ring
were refined isotropically. In clear contrast to the molecular
structures of complexes 1 and 3, all the aromatic rings distri-
bute uniformly in the space to minimize electrostatic repulsion
between them.
It is clear that there is no significant difference in the Pt–P2
bond distance (Ptrans to the thiolate ligand) for the three
complexes. Bond lengths in similar complexes that have phos-
phorus and sulphur ligands trans to each other are those
of cis-[Pt(SPh)(PhSCSO)(PPh3)2] (2.287(3) Å),20a [Pt(SPh)2-
(Ph2CHQCHPPh2)] (Pt(1)–P(1) 2.2362(18) Å and Pt(1)–P(2)
2.2462(18) Å)20b and [Pt(SPh)2(dppf)] (dppf = Fe(Z5-C5H4PPh2)2,
Pt1–P1 2.313(1) Å and Pt1–P2 2.294(1) Å).20c
1
Fig. 3 Ball and stick and space-filling representations with the numbering
This is an unexpected result because the JPt–P
is very
trans
scheme of the molecular structure of [Pt(SC6H5)(triphos)](CF3SO3)
8
different between them (vide infra) and therefore this similarity
in bond lengths probably reflects factors such steric hindrances,
crystal packing and the restraints imposed by the double-
chelating triphos ligand which are not present in solution.
determined by single crystal X-ray diffraction. Pt = gray, P = pink,
S = yellow, C = black, H = white. The counterion has been omitted for clarity.
expected bond lengths and angles for platinum–thiolate
complexes.17–21
3.3. Solution nuclear magnetic resonance
[Pt(SC6F4CF3-4)(triphos)][OTf] 1. Isolated crystals belong to In terms of nuclear magnetic resonance, the magnetic systems
%
the triclinic space group P1. There is a complete platinum corresponding to each of the fluorinated rings included in this
complex monocation and one trifluoromethanesulfonate anion work are p-C6F4(CF3) and p-C6H4(CF3) AA0BB0X3; C6F5, and C6H5
in the asymmetric unit; both trifluoromethyl groups on the AA0BB0C; p-C6F4H and p-C6H4F AA0BB0X; and 2,4-C6H4F2
1
structure are disordered. The electron-deficient character of the ABCXY. The H and 19F NMR parameters for compounds 1 to
perfluorinated aromatic ring of the thiolate ligand SC6F4CF3-4 8 are listed in the experimental section.
induces an aromatic interaction22 with one of the electron-rich
As expected, the 31P{1H} NMR spectra of compounds 1 to 8
phenyl rings of the triphos ligand with an interplanar distance reflect the square planar structures of these complexes and
634 | New J. Chem., 2015, 39, 631--638
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Table 2 31P chemical shifts (ppm) and coupling constants (Hz) for compounds [Pt(SRF)(triphos)]+ 1 to 8 and selected examples of published parameters
for [PtX(triphos)]+ compounds
31
31
Compound
d
P
cis
ppm
d
P
ppm
1JPt–P Hz
1JPt–P
Hz
trans
2JP
Hz
cis–Ptrans
trans
cis
[Pt(SC6F4(CF3-4))(triphos)]+
[Pt(SC6F5)(triphos)]+
1
2
3
4
5
6
7
8
40.0
41.2
41.0
41.0
41.4
39.7
41.8
41.6
89.9
88.9
89.0
89.1
88.0
86.5
87.7
87.5
2519
2551
2550
2566
2599
2591
2613
2609
2524
2466
2465
2370
2354
2354
2313
2306
2.9
4.0
4.1
4.4
4.9
4.7
5.3
5.2
[Pt(SC6HF4-4)(triphos)]+
[Pt(SC6H4(CF3)-4)(triphos)]+
[Pt(SC6H3F2-2,4)(triphos)]+
[Pt(SC6H4F-2)(triphos)]+
[Pt(SC6H4F-4)(triphos)]+
[Pt(SC6H5)(triphos)]+
[Pt(OTf)(triphos)]+ 12c
[PtCl(triphos)]+ 12c
2513
2451
2323
2456
2442
2449
2417
2445
2373
2639
2745
3314
3080
2433
3065
3049
3016
2902
2725
2216
2190
1521
[Pt(SnR)(triphos)]+ 12c
[PtCl(triphos)]+ 12d
[Pt(SCN)(triphos)]+ 12d
[PtBr(triphos)]+ 12d
[PtI(triphos)]+ 12d
[Pt(NCS)(triphos)]+ 12d
[Pt(CN)(triphos)]+ 12d
[Pt(SMe)(triphos)]+ 12d
[Pt(Me)(triphos)]+ 12d
exhibit one resonance arising from the two phosphorus nuclei
Platinum–phosphorous coupling constants show differences
in the trans positions and one signal due to the third phos- of up to ca. 94 Hz for the cis configuration and much larger
phorus atom trans to the thiolate ligand. The relative ratio of differences of up to ca. 217 Hz for the trans arrangement. The
1
these signals is 2 : 1, respectively, and both have platinum magnitude of the coupling constant JPt–P decreases with a
cis
satellites due to coupling to 195Pt (33% natural abundance).
decrease in the degree of fluorination of the ring, from 2519 Hz
Some phosphorus–phosphorus magnetic couplings are when RF = C6F4(CF3) to 2608 Hz when RF = C6H5. In contrast,
unobservable, but this is expected for square-planar triphos 1JPt–P follows the opposite trend and goes from 2523 Hz when
trans
derivatives with all of the phosphorus atoms coordinated to the RF = C6F4(CF3) to 2313 Hz when RF = C6H5, reflecting the cis and
same metal centre. The range of chemical shifts for the trans influences on the order of this series.
phosphorus atoms in cis and trans positions is very narrow,
39.7–41.8 and 89.9–86.5 ppm, respectively. The NMR parameters the linear relationship between JPt–P
Several correlations of the NMR data are found. For example,
1
2
and JP
is shown
trans–Pcis
trans
for compounds 1 to 8 are collected in Table 2.
in Fig. 4.
1
1
Fig. 4 Linear relationship between JPt–P
and 2JP
for compounds 1 to 8. JPt–P
= ꢀ95.567(2JP
) + 2817.3 with R2 = 0.9408.
–P
trans cis
–P
cis trans
trans
trans
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1
1
Fig. 5 Mulliken S atom charge on the free thiols versus the JPt–P
R2 = 0.9655.
for compounds 1 to 8. JPt–P
= 1233.1(Mulliken S charge) + 2117.2 with
trans
trans
As an additional element, the Mulliken charge on each
In addition, Fig. 4 shows the relationship between the cis
sulphur atom in the corresponding free thiol (calculated by and trans coupling constants and the corresponding chemical
the non-geometrical restricted optimisation of the structure shifts, which show that in this series, both effects are well
using Gaussian 03W23) is shown in Fig. 5 plotted against the detected and follow the same order.
1JPt–P
for the corresponding compound. Although this basic
The bond lengths found for Pt–Ptrans when the opposite
trans
calculation level accounts for the electronic effects on single ligands are SC6F4CF3-4, SC6HF4-4 and SC6H5 are practically
molecules, there is a remarkable linear correlation for compounds identical, and therefore, in our case, the crystallographic
1 to 8 with the presumably more electronegative ligands having evidence does not show a significant difference in the trans
the more positively charged sulphur atoms.
influence of these ligands.
As suggested by the NMR data, the proposed order of the trans
1
influence (decreasing JPt–P coupling constants, increasing the
trans
Acknowledgements
trans influence) is SC6F4CF3-4 o SC6F5 E SC6HF4-4 o SC6F4CF3
o SC6H3F2-2,4 o SC6H4F-2 E SC6H4F-4 o SC6H5. The thiolate
ligand series should be put in place of the SPh ligand of
the following sequence of the strength of the trans influence
suggested from a very sound study of this parameter: Ph 4 Me 4
SPh 4 SePh 4 NO2 4 I 4 N34 Br 4 Cl 4 AcO 4 CF3COO 4
F 4 NO3.24
This work was supported by CONACYT (Project CB-2012-
177498) and DGAPA-UNAM (Project IN-202314). We thank
Mr Esteban Padilla Mata for experimental assistance.
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