Selective cleavage by acids of one metal-carbon σ-bond of a bis(ortho-platinated) triarylphosphane: A31P NMR trans-influence series based on the unit Pt(κ2-C6H 3-5-Me-2-PPh2)(PPh2-4-tol)

Article abstract of DOI:10.1002/ejic.200800333

Supporting information for this article is available on the WWW under http://www.eurjic.org or from the author. Treatment of the bis(chelate) complex cis-[Pt(κ²-C₆H₃-5-Me-2-PPh ₂)₂] (1) with strong acids causes selective cleavage of one of the metal-aryl bonds to give cis-[PtX(κ²-C ₆H₃-5-Me-2-PPh₂)(PPh₂-4-tol)] [X = Cl (2), Br (3), I (4), ONO₂ (5) and OCOCF₃ (6)], from which a series of neutral and cationic derivatives can be derived by metathetical reactions. The complexes 2 and 6 rearrange spontaneously to the corresponding trans isomers, this reaction being promoted by CO. The J(Pt-P) values for the phosphorus atom of the four-membered ring can be ordered to establish a trans-influence series of anionic ligands X and neutral ligands L, which correlates well with, but is more extensive than, that based earlier on PtMe(dppe) complexes. Single-crystal X-ray structural analysis of trans-[Pt(κ¹-OCOCF₃)(κ²-C ₆H₃-5-Me-2-PPh₂)(PPh₂-4-tol)] (trans-6), cis-[PtX(κ²-C₆H₃-5-Me-2- PPh₂)(PPh₂-4-tol)] [X = Cl (2), CN (11), Me (43) and C₆F₅ (45)], and [Pt(κ²-C ₆H₃-5-Me-2-PPh₂)(PPh₂-4-tol) ₂]BF₂ (34) show these complexes to have distorted square-planar geometry. The Pt-P distances to the phosphorus atom of the four-membered ring in 2, 11, 43 and 45 broadly follow the trend of J(Pt-P) values, Cl^- being placed near the bottom and Me^- near the top of the trans-influence series, but the corresponding Pt-P distance in 34 is out of line. The Pt-P distances to PPh₂-4-tol cis to X or L tend to decrease with increasing trans-influence of X or L, in agreement with previous indications of a ligand cis-influence that runs opposite to the trans-influence. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200800333

FULL PAPER
DOI: 10.1002/ejic.200800333
Selective Cleavage by Acids of One Metal–Carbon σ-Bond of a Bis(ortho-
31
platinated) Triarylphosphane: A P NMR trans-Influence Series Based on the
Unit Pt(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)
Martin A. Bennett,[a] Suresh K. Bhargava,*[b] Steven H. Privér,[b] and Anthony C. Willis[a]
Keywords: Platinum / ortho-Metallated complexes / trans-Influence
Treatment of the bis(chelate) complex cis-[Pt(κ2-C6H3-5-Me-
2-PPh2)2] (1) with strong acids causes selective cleavage of
one of the metal–aryl bonds to give cis-[PtX(κ2-C6H3-5-Me-
2-PPh2)(PPh2-4-tol)] [X = Cl (2), Br (3), I (4), ONO2 (5) and
OCOCF3 (6)], from which a series of neutral and cationic de-
rivatives can be derived by metathetical reactions. The com-
plexes 2 and 6 rearrange spontaneously to the corresponding
trans isomers, this reaction being promoted by CO. The J(Pt-
P) values for the phosphorus atom of the four-membered ring
can be ordered to establish a trans-influence series of anionic
ligands X and neutral ligands L, which correlates well with,
but is more extensive than, that based earlier on PtMe(dppe)
complexes. Single-crystal X-ray structural analysis of trans-
[Pt(κ1-OCOCF3)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (trans-
6), cis-[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] [X = Cl (2),
CN (11), Me (43) and C6F5 (45)], and [Pt(κ2-C6H3-5-Me-2-
PPh2)(PPh2-4-tol)2]BF4 (34) show these complexes to have
distorted square-planar geometry. The Pt–P distances to the
phosphorus atom of the four-membered ring in 2, 11, 43 and
45 broadly follow the trend of J(Pt–P) values, Cl– being
placed near the bottom and Me– near the top of the trans-
influence series, but the corresponding Pt–P distance in 34 is
out of line. The Pt–P distances to PPh2-4-tol cis to X or L tend
to decrease with increasing trans-influence of X or L, in
agreement with previous indications of a ligand cis-influence
that runs opposite to the trans-influence.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
where γPt, γP are the magnetogyric ratios for the two spin-
1/2 nuclei, ∆E is a mean singlet-triplet excitation energy,
1. Introduction
The trans-influence of a ligand was first defined by Pid-
cock, Richards and Venanzi[1] as the extent to which that
ligand weakens the bond trans to it in the ground state of
a complex, particularly a planar platinum(II) complex; it is
to be distinguished from the trans-effect, which refers to the
rates of replacement of groups trans to the ligand, i.e., a
kinetic effect.[2–4] Although many physical techniques have
been employed to study the trans-influence,[5] one of the
most versatile remains that used by Pidcock et al., namely,
the evaluation of 195Pt-31P NMR coupling constants, J(Pt-
P). It is assumed that this coupling is determined by the
Fermi contact term, i.e., by the interaction between the nu-
clear spin and the s-electrons, which alone have finite den-
sity at the nucleus. The coupling is given by the proportion-
ality
2
αPt2, αP are the s-characters of the hybrid orbitals used by
the respective atoms in the Pt–P bond, and |ΨPt(0)|2,
|ΨP(0)|2 are the squares of the magnitudes of the valence-
state s-orbitals evaluated at the parent nucleus.
2
In most cases, it appears that αPt is the dominant influ-
ence, so that changes in J(Pt-P) reflect primarily variations
in the s-character of the Pt–P bond; ligands of high trans-
influence make a high demand on Pt 6s-orbital character.
This approach has been applied to various P-donor com-
plexes of platinum(II) and used to construct trans-influence
series.[6–10] It is also of interest to correlate these series with
those acquired by the ordering of parameters obtained by
other physical techniques, in particular, with bond lengths
obtained by X-ray crystallography[11–18] and with other di-
1
rect and indirect NMR coupling constants, such as J(Pt-
1J(Pt-P) ϰ γPtγP(∆E)–1αPt2αP2|ΨPt(0)|2|ΨP(0)
|
2
1
2
2
H), J(Pt-C), J(Pt-CH3) and J(Pt-CF3).[5,19,20]
Although there are numerous X-ray crystallographic
studies on planar platinum(II) complexes containing terti-
ary phosphanes, only in a series of cis-[PtCl2(PEt3)(L)] com-
plexes has a systematic comparison of 1J(Pt-P) with (Pt-Cl)
bond length data been carried out to obtain information
about trans- and cis-influences.[11–14] We describe here a
series of ortho-metallated triarylphosphane complexes of
platinum(II) whose 31P NMR spectroscopic data provide a
trans-influence series for a wide range of neutral and an-
[a] Research School of Chemistry, Australian National University,
Canberra, ACT 0200, Australia
Fax: +61-2-6125 3216
E-mail: bennett@rsc.anu.edu.au
[b] School of Applied Sciences (Applied Chemistry), RMIT Uni-
versity,
GPO Box 2476V, Melbourne, Victoria 3001, Australia
Fax: +61-3-9925 3365
E-mail: suresh.bhargava@rmit.edu.au
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Eur. J. Inorg. Chem. 2008, 3467–3481
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3467

M. A. Bennett, S. K. Bhargava, S. H. Privér, A. C. Willis
FULL PAPER
ionic ligands. The results can be compared with those ob- Table 1. 31P NMR spectroscopic data for neutral cis-[PtX(κ2-C6H3-
5-Me-2-PPh2)(PPh2-4-tol)] complexes and cis-[PtL(κ2-C6H3-5-Me-
tained by single-crystal X-ray structural determinations on
selected members.
2-PPh2)(PPh2-4-tol)]BF4 salts.[a–c]
X or L
δ(PA)
1J(Pt-P) 2J(P-P)
δ(PB) 1J(Pt-P)
[e]
L = Ph3PO (18)[d]
L = THF (17)
23.4
23.6
21.5
21.5
17.9
18.5
19.0[g]
17.9
22.8
16.7
19.4
21.3
17.0
16.5
21.5
16.9
15.7
16.7
16.3
17.2
16.8
16.7
17.6
16.6
15.1
18.8
19.2
18.8
18.6
16.5
14.7
18.1
13.8
18.5
15.6
15.0
18.3
14.3
16.8
16.7
19.2
19.2
17.0
21.6
19.6
1948
–82.3
–81.4
–83.9
–83.0
–83.0
–72.8
–81.8
–73.6
–81.9
–80.0
–70.0
–81.6
–70.3
–78.0
–81.6
–74.4
–78.1
–71.8
–72.3
–80.3
–80.7
–80.7
–78.3
–79.7
–71.5
–68.2
–68.8
–83.0
–72.8
–72.2
–72.4
–75.8
–66.6
–78.7
–69.2
–76.5
–86.5
–73.5
–70.1
–67.8
–70.3
–68.3
–64.0
–50.7
–55.9
3835
3652
3574
3507
3487
3392
3380[h]
3365
3314
3283
3274
3272
3260
3243
3236
3207
3201
3168
3108[m]
3096
3062
3055
3039
3011
3002
2923
2888[o]
2888
2883
2845
2819
2802
2765
2640
2635
2599
2544
2504
2207
2132
2111
1969
1803
1122
1041
2. Results and Discussion
2129
2068
2041
1956
1990
1999
1998
1928
1932
1903
2056
1923
1932
2044
2023
2009
1948
1942
2016
2017
2028
1957
2056
1949
2041
2078
1975
2059
2010
1940
2006
2032
2007
2026
1832
2063
1840
1888
2004
1895
1894
1981
2123
2071
6.4
7.0
5.7
8.6
5.9
4.6
5.4
4.8
7.6[j]
7.0
7.7
6.9
7.4[j]
6.4
8.4
4.9
7.7
7.2
10.0
10.2
10.1
9.6
9.8
9.4
8.8
8.7
8.3
11.4
10.7
10.5
7.0
X = ONO2 (5)
X = OCOCF3 (6)
L = MeCN (26)
X = Cl (2)
X = F (7)[f]
X = Br (3)
2.1 Formation of cis-[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-
tol)] (X = Cl, Br, I, ONO2, OCOCF3)
When a THF (for definitions of abbreviations, see Exper-
imental Section) solution of the bis(chelate) complex cis-
[Pt(κ2-C6H3-5-Me-2-PPh2)2] (1),[21] which contains two
four-membered rings, is treated with a strong acid, such as
HCl, HBr, HI, HNO3 or CF3COOH, one of the Pt–aryl
bonds is cleaved selectively to give cis-[PtX(κ2-C6H3-5-Me-
2-PPh2)(PPh2-4-tol)] [X = Cl (2), Br (3), I (4), ONO2 (5)
and OCOCF3 (6)] in high yield (Scheme 1). Also formed in
a small amount is the product derived by cleavage of both
Pt–C bonds, [PtX2(PPh2-4-tol)2], which is easily removed by
column chromatography. In the case of HI, a significant
amount of the diiodoplatinum(IV) complex [PtI2(κ2-C6H3-
5-Me-2-PPh2)2][21] also formed, possibly arising from the
addition of traces of iodine in the HI to 1. Complexes 3
and 4 can also be prepared by metathesis of 2 with LiBr or
NaI, respectively, in acetone. All the complexes except 5
show the expected molecular ion peak in their ES mass
spectra.
L = NEt3 (20)
X = NCS (14)[i]
L = PhCϵCPh (42)
X = OCOPh (10)
L = MeCϵCMe (41)
X = NCO (13)
X = OCOMe (9)
X = N3 (12)
X = I (4)
X = Ph3PS (32)[k]
X = Ph3PSe (33)[l]
L = o-MeC6H4NH2 (22)
L = PhNH2 (21)
L = m-MeC6H4NH2 (23)
L = NH3 (19)
L = p-MeC6H4NH2 (24)
L = SPh2 (29)
X = SCN (14)[n]
X = SeCN (15)
L = C5H5N (25)
L = THT (30)
L = SMe2 (27)
L = SEt2 (28)
X = OH (8)
L = SbPh3 (36)
L = DMSO (31)
L = AsPh3 (35)
L = CO (39)
X = NO2 (16)
L = tBuNC (40)
X = CN (11)
11.4
[e]
13.4
13.4
8.6
Scheme 1.
11.7
11.3
18.0
14.4
16.0
11.4
10.2
11.5
Evidence for the presence of only one four-membered
ring in complexes 2–6 is provided by spectroscopic data,
particularly the 31P NMR spectra, which consist of a pair
of doublets, with 195Pt satellites, at δ ≈ 20 and –60 to
–80 ppm. The former is unexceptional for triarylphos-
phanes coordinated to platinum(II), while the highly
shielded resonance is typical of a phosphorus atom in a
strained four-membered chelate ring.[22] The IR spectrum
of 2 shows typical ortho-metallation bands at 1569 and
725 cm–1,[23,24] together with a band at 314 cm–1 assignable
L = PPh2-4-tol (34)
L = P(OPh)3 (37)[p]
L = P(OMe)3 (38)[q]
X = C6F5 (45)
X = Me (43)
X = Ph (44)
[a] Measured in CDCl3, except where stated otherwise. [b] PA refers
to PPh2-4-tol, PB refers to C6H3-5-Me-2-PPh2. [c] Estimated errors
in 2J(P-P) and 1J(Pt-P) are Ϯ0.5 Hz and Ϯ3 Hz, respectively. [d]
δ(Ph3PO) = 42.5 ppm, 195Pt satellites not observed. [e] Coupling
not observed. [f] In CD2Cl2. [g] J(P-F) = 26.1 Hz. [h] J(P-F) =
to ν(PtCl) for Cl trans to a tertiary phosphane in a planar 161.5 Hz. [i] 31P NMR (CD2Cl2, –90 °C): δ(PA) = 16.5 [d, J(P-P) =
platinum(II) complex.[25] The pair of doublets in the 31P
NMR spectrum at δ = 18.5 and –72.8 ppm [J(P-P) =
5.8 Hz] is associated with Pt-P coupling constants of
8.2 Hz, J(Pt-P) = 1916 Hz] ppm, δ(PB) = –78.9 [d, J(P-P) = 7.6 Hz,
J(Pt-P) = 3249 Hz] ppm. [j] Coupling not resolved on PB resonance
(see text). [k] δ(Ph3PS) = 41.8 [3J(P-P) = 6.5, 6.5 Hz, 2J(Pt-P) =
2
68.7 Hz] ppm. [l] δ(Ph3PSe) = 27.6 [3J(P-P) = 9.0, 9.0 Hz, J(Pt-P)
= 77.0 Hz, J(Se-P) = 602 Hz] ppm. [m] J(Se-P) = 71.3 Hz. [n] 31P
NMR (CD2Cl2, –90 °C): δ(PA) = 20.4 [d, J(P-P) = 10.0 Hz, J(Pt-
P) = 2088 Hz] ppm, δ(PB) = –66.8 [d, J(P-P) = 10.0 Hz, J(Pt-P) =
2952 Hz] ppm. [o] J(Se-P) = 82.2 Hz. [p] δ[P(OPh)3] = 91.9 [J(P-P)
= 596 Hz (trans), 26.5 Hz (cis), 1J(Pt-P) = 4914 Hz] ppm. [q]
1990 Hz and 3392 Hz, respectively, corresponding to P
trans to the η1-carbon atom and the chloride ion.[9,26] The
structure of 2 has been confirmed by a single-crystal X-ray
diffraction study (see later).
The 31P NMR spectra of the complexes 3–6 are similar
1
δ[P(OMe)3] = 103.1 [J(P-P) = 576 Hz (trans), 28.0 Hz (cis), J(Pt-
to that of 2, the data being collected in Table 1. The IR P) = 4807 Hz] ppm.
3468
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Eur. J. Inorg. Chem. 2008, 3467–3481

Bis(ortho-platinated) Triarylphosphane
spectrum of the nitrato complex 5 contains bands at 1480 plexes.[32] The facile isomerisation of 6, even in the absence
and 1272 cm–1 due to the asymmetric and symmetric of CO, must arise from the lability of coordinated trifluo-
ν(NO ) vibrations. The separation (∆ν) of 208 cm–1 is con- roacetate, which can ionise to generate a labile, coordina-
˜
2
sistent with the presence of κ1-ONO2, as in complexes such tively unsaturated, three-coordinate, or four-coordinate, sol-
as [Re(ONO2)(CO)5] and [Pt(ONO2)2L2] (L = substituted vent-stabilised, cation. Detailed studies of complexes of the
pyridine);[27,28] other modes of nitrate coordination gen- type cis-[Pt(R)(L)(solvent)]+ (R = alkyl or aryl, L = tertiary
erally give larger ∆ν values. Similarly, the IR spectrum of phosphane) have shown that formation of the thermody-
˜
the trifluoroacetato complex 6 exhibits bands at 1699 and namically favoured trans-isomer is promoted by electron-
1409 cm–1 (∆ν = 290 cm–1) arising from the asymmetric and donating substituents on the tertiary phosphanes, steric re-
˜
symmetric ν(COO) vibrations, the value of ∆ν being indica- pulsion between the tertiary phosphanes, distortion of the
˜
tive of κ1-OCOCF3;[29–31] values of ∆ν less than 200 cm–1 four-coordinate, planar geometry and interaction of the
˜
are generally associated with chelating and bridging modes vacant coordination site with β-hydrogen atoms on R.[33]
of coordination of trifluoroacetate.
When a solution of 2 in CDCl3 is set aside for 24 h, par-
tial isomerisation to the trans-isomer (ca. 10%) occurs, as
2.2 Formation of Ligand Derivatives Containing the Unit
shown by 31P NMR spectroscopy. This process goes to
cis-[Pt(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)]: General
completion under CO in 30 min, presumably being cata-
lysed by reversible opening of the chelate ring and coordi-
Comments
nation of CO, as suggested also for the CO-catalysed dimer-
The chloride ion in 2 is readily replaced by a wide range
isation of 1.[21] A similar process occurs even more readily of other anionic or neutral ligands, either by metathesis
for the nitrato, trifluoroacetato, and benzoato complexes, 5, with the appropriate alkali metal salt, or by abstraction
6 and 10, respectively (see section 2.2.1). Recrystallisation with a silver salt (usually AgBF4) in the presence of a neu-
of the trifluoroacetato complex gave trans-6, whose X-ray tral ligand. The results are shown in Scheme 2. Most of
structure (see later) confirmed the presence of κ1-OCOCF3. the complexes have been isolated in ca. 80–90% yields as
The trans-isomer is formed quantitatively over 24 h from a colourless or off-white solids and satisfactory elemental
solution of 6 in C6D6 as shown by 31P NMR spectroscopy; analyses obtained for a representative selection. Some of
under CO, the reaction is complete after 30 min. The 31P the cationic complexes are unstable and could be identified
NMR spectra of trans-2 and trans-6 consist of a pair of only by means of their 31P NMR spectra (see section 2.2.2).
doublets, with 195Pt satellites, in the region of δ ≈ 25 (PPh2- The mass spectra of the isolated complexes generally show
4-tol) and –60 (C6H3-5-Me-2-PPh2) ppm, the coupling con- the expected parent ion, [M]+, or, less frequently, [M – li-
2
stant J(P-P) being ca. 450 Hz; this value is diagnostic of gand]+, as the highest peak, corresponding to the fragment
trans-tertiary phosphanes in planar platinum(II) com- [Pt(C6H3-5-Me-2-PPh2)(PPh2-4-tol)]+, and the IR spectra
Scheme 2.
Eur. J. Inorg. Chem. 2008, 3467–3481
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3469

M. A. Bennett, S. K. Bhargava, S. H. Privér, A. C. Willis
FULL PAPER
of the neutral complexes contain the usual ortho-metalla- cation cis-[Pt(THF)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)]+
tion bands at ca. 1570 and 725 cm–1. The 31P NMR spectra (17) (see below) with NaOH were unsuccessful, although
generally consist of a pair of doublets with 195Pt satellites, these procedures have worked well for many other hy-
that due to PPh2-4-tol being in the region of δ ≈ 20 ppm droxido organoplatinum(II) complexes containing tertiary
with J(Pt-P) ≈ 2000 Hz. The second doublet, due to the phosphanes.[9,44,45] The silver oxide procedure has been
phosphorus atom in the four-membered ring, varies mark- used to prepare functionalised σ-alkyl complexes of plati-
edly in both chemical shift (δ = –50.7 to –86.5 ppm) and num(II) from cis-[PtCl2(PEt3)2][46] and trans-[PtXRL2]
in J(Pt-P) (1122–3835 Hz), depending on the nature of the (X = I, R = Me, L = PPh3; X = Cl, R = Ph, L = PMe2Ph,
introduced ligand. The small doublet coupling (5–10 Hz) is PEt3)[44] in the presence of acidic hydrocarbons such as ace-
as expected for inequivalent cis-phosphorus nuclei in plati- tone and nitromethane. The 1H NMR spectrum of complex
num(II) complexes. The observed pattern in the 31P NMR 8 shows a broad peak assigned to OH at δ = 1.25 ppm,
spectra becomes more complex for complexes in which the together with the expected aromatic methyl resonances at δ
introduced ligand is a tertiary phosphane, phosphane chal- = 2.30 and 2.33 ppm, and aromatic multiplets at δ = 6.8–
cogenide or phosphite ligand (see below). We now discuss 8.2 ppm. The ES mass spectrum contains a peak at m/z =
individual members of the series in more detail, and, unless 763, corresponding to the [M – H]+ fragment. Weak bands
specified otherwise, compound numbers refer to the cis-iso- at 3657 and 1027 cm–1 in the IR spectrum are tentatively
mer.
assigned to O–H stretching and Pt–OH bending vibrations,
respectively.[47]
2.2.1 Neutral Complexes cis-[PtX(κ2-C6H3-5-Me-2-PPh2)-
(PPh2-4-tol)] (X = F, OH, OCOMe, OCOPh, N3, NCO,
NCS, NCSe, NO2)
The acetato and benzoato complexes, 9 and 10, respec-
tively, were readily prepared by treatment of 2 with the ap-
propriate silver salt. Unlike the corresponding trifluoroacet-
The
fluoro
complex
cis-[PtF(κ2-C6H3-5-Me-2- ate, they cannot be prepared by treatment of 1 with the
PPh2)(PPh2-4-tol)] (7) was obtained in good yield by treat- appropriate acids; evidently, acetic and benzoic acids are
ment of 2 in CH2Cl2 with AgF in the absence of light over too weak to cleave the Pt–C σ-bonds. The IR spectra of
a period of 3 d. In the 31P NMR spectrum, the pair of dou- complexes 9 and 10 show bands at ca. 1600 and 1300 cm–1
blets due to the inequivalent phosphorus nuclei are further due to symmetric and asymmetric ν(COO) vibrations; the
split by coupling with 19F (I = 1/2, 100%) [2J(P-F) = separations (∆ν) are typical of κ1-OCOR,[30,48,49] as found
˜
26.1 Hz (cis) and 161.5 Hz (trans)]. The 19F NMR spectrum also in cis- and trans-6. The cyanido complex cis-
shows a doublet of doublets centred at δ = –285.1 ppm, [Pt(CN)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (11) is also
arising from coupling with two inequivalent phosphorus obtained in a similar way, i.e., by treatment of 2 with
nuclei, together with 195Pt satellites [J(Pt-F) = 241 Hz], AgCN. It shows a typical ν(CN) band in its IR spectrum
these data being consistent with the presence of a covalent at 2128 cm–1. The structure has been confirmed by X-ray
Pt–F bond.[34–36] The Pt-F and Pt-P couplings are repro- crystallography (see below). An attempt to prepare a for-
duced in the 195Pt NMR spectrum, which consists of a mato analogue of 9 and 10 by addition of sodium formate
doublet of double doublets centred at δ = –4243 ppm (rela- to a solution of 17 that had been generated in situ from 2,
tive to aqueous Na2PtCl6) [J(Pt-F) = 235 Hz, J(Pt-P) = led to rapid deposition of Pt metal (see below).
1999, 3376 Hz].
The complexes containing the pseudohalides azide, cya-
In comparison with the plethora of platinum complexes nate, thiocyanate and selenocyanate were prepared by treat-
with chloride, bromide and iodide, those with fluoride are ing a CH2Cl2 solution of 2 with a methanol solution of the
fairly rare and have only recently received attention.[37–39] It appropriate alkali metal salt. The 31P NMR spectrum of
has usually been assumed, on the basis of the Class A char- the azido complex 12 showed the expected pair of doublets,
acter of fluoride ion and the Class B character of platinum, and the IR spectrum showed a strong band at 2043 cm–1
that Pt–F bonds will be relatively weak, and only a limited due to ν(NϵN).[50] The 31P NMR spectrum of the cyanato
number of preparative methods have been developed. complex 13 shows a broad, unresolved peak with 195Pt sat-
Moreover, the tendency of F– to form hydrogen bonds with ellites for the phosphorus atom trans to NCO; the broaden-
water and other protic molecules can result in the isolation ing may be caused by scalar coupling of 31P with the quad-
–
of complexes containing coordinated OH–, H2O or HF2 . rupolar 14N nucleus.[51,52] The IR spectrum of 13 contains
Nevertheless, a number of Pt–F complexes containing a strong ν(CN) band at 2214 cm–1, which is in the region
“soft” co-ligands have been characterised structurally, e.g., usually observed for N-bonded NCO complexes,[53] but
cis-[PtF{CH(CF3)2}(PPh3)2],[40] [PtF(PEt3)3]BF4,[41] [PtF- there was also a shoulder at 2170 cm–1. We did not establish
(CH3)3]4,[42] and trans-[PtF(Ph)(PPh3)2].[43]
whether this is due to the formation of some KNCO in the
Treatment of a solution of 2 with an excess of moist KBr disc or to a solid-state splitting; it seems unlikely that
Ag2O in the dark for 3 d gave the hydroxido complex, cis- some O-bonded isomer is present in the isolated solid.
[Pt(OH)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (8) contami-
The IR spectrum of the thiocyanato complex cis-
nated with ca. 5% of the starting material. Attempts to [Pt(CNS)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (14) shows
force the reaction to completion by extending the reaction only one ν(CN) band at 2212 cm–1 in CHCl3 but two bands
time, or by sonication, caused extensive decomposition. at 2212 and 2093 cm–1 in a KBr disc, which are probably
Likewise, the attempted reactions of 2 or the derived THF due to S- and N-linkage isomers. We were unable to con-
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Bis(ortho-platinated) Triarylphosphane
1
firm this explanation by assigning bands due to ν(M–NCS),
The H NMR spectrum of the SMe2 complex 27 shows
ν(CS) or δ(NCS)[54] because of interfering ligand absorp- the aromatic multiplets and two aromatic methyl reso-
tion, but the assumption is supported by the 31P NMR nances arising from the inequivalent phosphane ligands.
spectrum, which shows two pairs of doublets of approxi- The methyl protons of SMe2 appear as two singlets flanked
mately equal intensity, at δ = 18.8 and –68.2, and at 16.7 by broad 195Pt satellites [3J(Pt-H) = 40.6 Hz]; we have not
and –80.0 ppm. The latter pair is assigned to the NCS iso- investigated whether this is caused by inequivalence of the
mer on the basis of the observed broadness of the peak at methyl groups or coupling with 31P. The ammonia complex
δ = –80.0 ppm, which presumably arises from interaction 19 also shows the expected aromatic and methyl resonances
with the 14N quadrupole; this peak sharpens as the tem- in its H NMR spectrum, together with a broad peak at δ
1
perature is lowered, as observed in related systems.[52]
= 3.42 ppm with 195Pt satellites [2J(Pt-H) ≈ 30 Hz] assigned
The selenocyanato complex cis-[Pt(CNSe)(κ2-C6H3-5- to coordinated NH3. The H NMR spectrum of the pyr-
Me-2-PPh2)(PPh2-4-tol)] (15) could not be isolated in a idine complex 25 contains peaks at δ = 7.93 [t, J(H-H) =
pure state because of its ready decomposition to the cyan- 7.7 Hz], 8.39 [m with br. 195Pt satellites, J(Pt-H) ≈ 15 Hz],
ido complex 11, among other unidentified products. The and 8.75 [dd, J(H-H) = 1.5, 6.3 Hz] ppm due to the coordi-
31P NMR spectrum of 15 shows a pair of sharp doublets at nated pyridine ligand, these signals being shifted signifi-
1
δ = 19.2 and –68.8 ppm, the latter displaying an additional cantly from those of the free ligand.
2
coupling of 82.2 Hz that is typical of J(77Se-31P);[55,56] this
The 1H NMR spectrum of cis-[Pt(κ2-C6H3-5-Me-2-
observation is consistent with the presence of SeCN. Thus, PPh2)(PPh2-4-tol)2]+ (34) shows the expected three aromatic
for the three complexes containing XCN as ligands, only methyl singlets, and correspondingly, the 31P NMR spec-
the N-bound species is present when X = O, only the X- trum contains three doublets of doublets, with 195Pt satel-
bound species is present when X = Se, and both isomers lites, at δ = 23.0, 16.7 and –67.8 ppm due to the inequivalent
are formed when X = S. The trend is consistent with expec- PPh2-4-tol ligands and an ortho-metallated PPh2-4-tol
tations based on the hard/soft acid/base theory.
group. The resonances at δ = –67.8 and 23.0 ppm display
The nitro complex cis-[Pt(NO2)(κ2-C6H3-5-Me-2-PPh2)- a coupling of 368 Hz, showing that the phosphorus atoms
(PPh2-4-tol)] (16) was obtained almost quantitatively as an responsible for these signals are mutually trans.[32] All the
off-white solid by reaction of NaNO2 with a solution of 17. Pt-P couplings (2845, 2004 and 2132 Hz) are reproduced in
Its IR spectrum shows three strong bands at 1384, 1331 and the 195Pt NMR spectrum. The 31P NMR spectroscopic data
817 cm–1 corresponding to the asymmetric ν(NO2), sym- are very similar to those reported for [Pt(κ2-2-
metric ν(NO2) and δ(ONO) vibrations, respectively. The C6H4PPh2)(PPh3)2]+.[60] The structure of 34, as its BF4 salt,
separation between the first two bands is typical of κ-NO2 has been confirmed by X-ray crystallography (see below).
complexes and is much less than that of κ-ONO (nitrite)
The 31P NMR spectra of the P(OPh)3 and P(OMe)3 com-
complexes, which generally shows bands at ca. 1450 and plexes, 37 and 38 respectively, also show three well-sepa-
1100 cm–1 in their IR spectra.[57] Similar bands for κ-NO2 rated doublets of doublets, with 195Pt satellites, at δ ≈ 100,
have been observed in the complexes [Pt(NO2)2(cis- 20 and –70 ppm, the first and last being due to the phos-
Ph2PCH=CHPPh2)][58] and [Pt(en)2(µ-C5H4NO)2(NO2)- phite and the ortho-metallated phosphane, respectively, and
(NO3)][NO3]2 (C5H4NO = α-pyridonato),[59] and the mode with a P-P coupling of about 600 Hz.
of coordination has been confirmed by X-ray crystallogra-
2.2.3 η1-Organyl Complexes cis-[PtR(κ2-C6H3-5-Me-2-
PPh2)(PPh2-4-tol)] (R = Me, Ph, C6F5)
phy in the latter.
The chlorido complex 2 in THF reacts with methyllith-
2.2.2 Salts cis-[PtL(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-
ium and phenyllithium to give the corresponding η1-C-
tol)]BF4 (L = Various Neutral Ligands)
bonded complexes cis-[PtR(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-
As mentioned in section 2.2, these salts are obtained by tol)] [R = Me (43), Ph (44)] as colourless solids in 70–80%
abstraction of Cl– from 2 with AgBF4 in the presence of L, yield (Scheme 3). Their 1H NMR spectra show two aro-
as shown in Scheme 2. Those having L = Ph3PO (18), NH3 matic methyl resonances in the region δ = 2.3–2.4 ppm, and
(19), NEt3 (20), aromatic amines (21–24), pyridine (25), the spectrum of 42 also shows a triplet due to Pt–CH3 at δ
SMe2 (27), Ph3PS (32), Ph3PSe (33), PPh2-4-tol (34), AsPh3 = 0.93 [J(P-H) = 7.1 Hz] ppm flanked by 195Pt satellites
(35), SbPh3 (36) and P(OPh)3 (37) were isolated, usually as [J(Pt-H) = 74.7 Hz]. Similar spectral parameters for the Pt–
colourless or off-white solids; exceptionally, those derived CH3 resonances have been reported for cis-dimethylplati-
from o-, m- and p-toluidine were obtained as red or purple num(II) complexes PtMe2L2 containing either monodentate
solids, probably owing to the formation of organic oxi- tertiary phosphanes (L)[61] or bidentate ditertiary phospha-
dation products in the presence of traces of the Ag+ oxi- nes (L2).[62]
dant. The THF and MeCN salts, 17 and 26, could not be
Surprisingly, complex 2 failed to react with C6F5Li in
isolated; both isomerised rapidly to the corresponding diethyl ether, but the corresponding reaction with the tri-
trans-isomers. The salts containing L = SEt2 (28), SPh2 (29), fluoroacetato complex 6 gave cis-[Pt(C6F5)(κ2-C6H3-5-Me-
CO (39), MeCϵCMe (41) and PhCϵCPh (42) are also un- 2-PPh2)(PPh2-4-tol)] (45) as a colourless solid in ca. 80%
stable and were identified only by their 31P NMR spectra, yield. In contrast with 43 and 44, whose 31P NMR spectra
measured on solutions prepared in situ.
consist of the usual pair of doublets, the shielded resonance
Eur. J. Inorg. Chem. 2008, 3467–3481
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FULL PAPER
CN ≈ C6F5 Ͻ Me; the Pt–C distances in the chelate ring
remain equal, within experimental error, at 2.06 Å. The Pt–
P distances to PPh2-4-tol show a less marked trend in the
opposite direction, namely, 2.2903(7) Å (43), 2.3129(6) Å
(45), 2.3225(8) Å (11) and 2.3350(8) Å (2).
Scheme 3.
due to the phosphorus atom in the four-membered ring of
45 appears as an octet because of its coupling to 19F nuclei
of the trans-C6F5 group; the resonance due to the phospho-
rus atom of PPh2-4-tol that is cis to the C6F5 group shows
no such coupling and appears as the usual doublet. Similar
effects have been observed for the phosphorus atom trans
to the C6F5 group in, for example, cis-[Pt(OCH-
O)(C6F5)(PPh3)2][63] and [M(C6F5)(SC6F5)(dppe)] (M = Pd,
Pt).[64] The 19F NMR spectrum of 45 contains three mul-
tiplets (due to F-F coupling) at δF = –116.4, –164.4 and
–165.5 ppm assigned to the ortho-, meta- and para-fluorine
atoms of C6F5, respectively; as observed in other PtII-C6F5
complexes, the first resonance shows coupling with 195Pt
[3J(Pt-F) = 406 Hz]. The structures of complexes 43 and 45
have been determined by X-ray crystallography (see below).
Attempts to prepare a hydrido complex cis-[PtH(κ2-
C6H3-5-Me-2-PPh2)(PPh2-4-tol)] similar to 43–45 by treat-
ing either 2 or 6 with NaBH4 failed; reduction to metallic
platinum was observed.
Figure 1. Molecular structure of trans-[Pt(κ1-OCOCF3)(κ2-C6H3-5-
Me-2-PPh2)(PPh2-4-tol)] (trans-6). Ellipsoids show 30% probability
levels, and hydrogen atoms have been deleted for clarity. Selected
bond lengths [Å] and angles [°]: Pt(1)–P(1) 2.3153(8), Pt(1)–P(2)
2.2931(8), Pt(1)–C(2) 2.002(4), Pt(1)–O(1) 2.118(2); P(1)–Pt(1)–P(2)
165.30(3), P(2)–Pt(1)–O(1) 89.46(7), O(1)–Pt(1)–C(2) 173.66(11),
C(2)–Pt(1)–P(1) 69.2(1), P(1)–Pt(1)–O(1) 105.09(7), P(2)–Pt(1)–
C(2) 96.4(1).
2.3 Molcular Structures of trans-[Pt(κ1-OOCCF3)(κ2-
C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (trans-6), cis-[PtX(κ2-
C6H3-5-Me-2-PPh2)(PPh2-4-tol)] [X = Cl (2), C6F5 (45),
CN (11), Me (43)] and cis-[Pt(κ2-C6H3-5-Me-2-PPh2)
(PPh2-4-tol)2] BF4 (34)
These have been determined by single-crystal X-ray crys-
tallography and are shown, together with selected metrical
data, in Figures 1, 2, and 3 and S1–S3, respectively. All the
complexes show marked angular distortions from the ex-
pected square-planar geometry about the metal centre ow-
ing to the narrow bite angle (ca. 69°) of κ2-C6H3-5-Me-2-
PPh2, this value being typical of chelate ligands of the 2-
C6H4PR2 type.[65] Thus, in trans-6, the P–Pt–P unit deviates
by 15° from linearity, and the angle P(1)–Pt(1)–O(1) opens
to 105° from the expected value of 90° [P(1) is the phospho-
rus atom in the chelate ring]. In complexes 2, 11, 43, and
45, the angle subtended at the metal atom by the mutually
cis-phosphorus atoms is ca. 106°, probably as a conse-
quence of steric repulsion between the bulky ligand systems,
and the angle P(1)–Pt(1)–X, where X is the formally trans-
Figure 2. Molecular structure of cis-[PtCl(κ2-C6H3-5-Me-2-
PPh2)(PPh2-4-tol)] (2). Ellipsoids show 30% probability levels, and
hydrogen atoms have been deleted for clarity. Selected bond lengths
[Å] and angles [°]: Pt(1)–P(1) 2.2539(8), Pt(1)–P(2) 2.3350(8), Pt(1)–
C(2) 2.056(3), Pt(1)–Cl(1) 2.3560(7); P(1)–Pt(1)–P(2) 105.78(3),
P(2)–Pt(1)–Cl(1) 93.57(3), Cl(1)–Pt(1)–C(2) 91.81(9), C(2)–Pt(1)–
P(1) 68.78(9), P(1)–Pt(1)–Cl(1) 160.45(3), P(2)–Pt(1)–C(2)
174.42(9).
In complex 2, the Pt–Cl bond length of 2.3560(7) Å is
ligand atom, is only ca. 160°. In the same series, the Pt–P similar to those observed in other platinum(II) complexes
bond lengths in the chelate ring are 2.2539(8) Å (2), in which Cl is trans to PR3, e.g., 2.348(15) Å in cis-
2.3169(8) Å (11), 2.3174(6) Å (45) and 2.3324(7) Å (43), [PtCl2(PPh3)2],[66] 2.355 and 2.341 Å in [PtCl2(dppe)],[67]
which would correspond to a trans-influence order Cl Ͻ and 2.367(3) Å in cis-[PtCl2(SMe2)(PMe2Ph)].[68] The Pt–
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Bis(ortho-platinated) Triarylphosphane
tively), as observed also in 2, 11, 43 and 45. There are also
small but significant differences (3–4°) in many of the bond
angles about the platinum atom in 34 and in [Pt(κ2-2-
C6H4PPh2)(PPh3)2]SbF6, which presumably are caused by
lattice effects (different space groups, different anions). This
emphasises the caution to be exercised in interpreting small
changes in metrical data determined in the solid state, espe-
cially for ionic compounds.
2.4 31P NMR Spectra and the trans-Influence Series
The 31P NMR spectroscopic data for cis-[PtX(κ2-C6H3-
5-Me-2-PPh2)(PPh2-4-tol)] and cis-[PtL(κ2-C6H3-5-Me-2-
PPh2)(PPh2-4-tol)]+ (X = anionic ligand; L = neutral li-
gand) are collected in Table 1. The data are listed in order
of decreasing values of J(Pt-PB), PA and PB being the phos-
phorus atoms of PPh2-4-tol and the four-membered chelate
ring, respectively. The 31P chemical shifts of PA and PB fall
within fairly narrow ranges (δ = 14–24 and –65 to –87 ppm,
respectively), the only exceptions being the δ(PB) values of
ca. –50 ppm for X = Me (43) and Ph (44). The magnitude of
J(Pt-PA) also spans a fairly narrow range (1930–2100 Hz),
whereas J(Pt-PB) varies over a much wider range (1040–
3800 Hz) as X and L are varied, reflecting, at least to a first
approximation, changes in the electronic nature of X and L
(see Introduction). Similar behaviour was observed in the
Figure 3. Molecular structure of cis-[Pt(C6F5)(κ2-C6H3-5-Me-2-
PPh2)(PPh2-4-tol)] (45). Ellipsoids show 30% probability levels,
and hydrogen atoms have been deleted for clarity. Selected bond
lengths [Å] and angles [°]: Pt(1)–P(1) 2.3174(6), Pt(1)–P(2)
2.3129(6), Pt(1)–C(112) 2.051(2), Pt(1)–C(311) 2.061(2); P(1)–
Pt(1)–P(2) 105.87(2), P(2)–Pt(1)–C(311) 91.53(7), C(311)–Pt(1)–
C(112) 94.21(9), C(112)–Pt(1)–P(1) 68.38(6), P(1)–Pt(1)–C(311)
162.59(7), P(2)–Pt(1)–C(112) 173.56(6).
CN bond length of 1.999(4) Å in complex 11 is comparable series based on [PtR(dppe)] (R = Me, Ph, 1-cyclohexenyl).[9]
with the values of 2.018(5) and 2.002(5) Å observed in As in that series, there is no obvious correlation between
[Pt(CN)2(cis-dppen)].[69]
δ(PB) and J(Pt-PB).
The Pt–CH3 distance in 43 [2.089(3) Å] is similar to those
The listing of ligands in Table 1 gives the order of in-
found in [PtMe(n-C3F7)(dppe)] [2.109(7) Å][70] and creasing trans-influence [decreasing J(Pt-P)]. While there
[PtMe2(dppf)] [2.094(3), 2.102(4) Å],[62] and the Pt–C6F5 are some obvious exceptions and considerable overlap be-
distance in 45 [2.061(2) Å] is comparable with those found tween the ranges, the general trend of increasing trans-influ-
in many PtII-C6F5 complexes, e.g., [Pt(C6F5)2(dppb)] ence with decreasing electronegativity of the donor atom [O
[2.065(8) Å][71] and [Pt(C6F5)2(Ph2CHIPPh2)] [2.067(5) Å].[72] Ͻ N ≈ S Ͻ Se Ͻ As Ͻ P Ͻ σ-C] is followed. It has been
An almost identical distance [2.052(7) Å] was found for the pointed out[4] that derived trans-influence series depend
Pt–Ph bond in the similar non-fluorinated compound both on the type of complexes and on the physical property
[PtPh(κ2-2-C6H4PPh2)(PPh3)].[73]
studied. This remains true even when NMR coupling con-
The X-ray structure of trans-6 confirms the presence of stants form the basis of comparison. For example, one
1
monodentate trifluoroacetate, the Pt–O distance being series of increasing trans-influence based on J(Pt-P) for a
–
2.118(2) Å. The Pt–C distance in the four-membered che- range of platinum(II) complexes, is NO3 Ͻ I– ≈ Br– ≈ Cl–
–
–
late ring [2.002(4) Å] is significantly shorter than those in Ͻ NCS– ≈ NCO– ≈ N3 ≈ C5H5N Ͻ p-toluidine Ͻ NO2
Ͻ
2, 11, 43 and 45, reflecting the low trans-influence of tri- CN– ≈ P(OPh)3 Ͻ Me– Ͻ Ph–,[8] which differs from the
fluoroacetate. series in Table 1 in its lower placement of iodide ion and
In 34, the bond length of 2.3361(11) Å for Pt(1)–P(2) pyridine. For a series based on 2J(Pt-CH3), the order is
–
–
trans to the phosphorus atom in the chelate ring is only NO3 Ͻ Br– ≈ Cl– ≈ I– Ͻ N3 ≈ NCS– ≈ NCO–
Ͻ
–
slightly larger than that for phosphorus atom P(3) trans to MeCϵCMe Ͻ C5H5N Ͻ NO2 Ͻ AsPh3 Ͻ CO Ͻ CN– Ͻ
the metallated aryl ring [2.3294(11) Å], suggesting that the P(OPh)3 Ͻ SbPh3,[5] which also differs significantly from
trans-influences of the arylphosphane and aryl groups that in Table 1. In general, however, there is a reasonable
are comparable. However, the Pt–P bond length in the linear correlation between the J(Pt-P) values obtained in
chelate ring of 34 and in the non-methylated analogue the present work and those derived from studies of
[60]
[Pt(κ2-2-C6H4PPh2)(PPh3)2]SbF6
differ significantly [PtMeX(dppe)] and [PtMeL(dppe)]+ complexes,[9,71,74] as
[2.3095(11) Å in 34, 2.3126(11) Å in the non-methylated an- shown in Figure 4. This is not surprising given the similar-
alogue], as also do the Pt–P bond lengths trans to the phos- ity of the nature and disposition of the donor sets, and it
phorus atom in the chelate ring [2.3361(11), 2.3079(13) Å, suggests that the marked distortion from strictly planar ge-
respectively]. The P–Pt–P (trans) angle in both structures ometry of the 5-Me-2-C6H3PPh2 complexes is unlikely to
deviates markedly from linearity (163° and 158.5°, respec- affect seriously the derived trans-influence series. The J(Pt-
Eur. J. Inorg. Chem. 2008, 3467–3481
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M. A. Bennett, S. K. Bhargava, S. H. Privér, A. C. Willis
FULL PAPER
Figure 4. Plot of J(Pt-P) [Hz] for cis-[PtMeX(dppe)] and cis-[PtMeL(dppe)]+ vs. J(Pt-P) [Hz] for cis-[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-
tol)] and cis-[PtL(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)]+ (X = anionic ligand, L = neutral ligand). Values of J(Pt-P) for the dppe complexes
are taken from ref.[9], except those for X = C6F5 (ref.[71]) and L = NH3 (ref.[74]). Values for X = Br and OCOPh have been omitted for
clarity. For other comments, see text.
P) values for the dppe complexes, for a given ligand, are of complex 34 and in its close relative [Pt(κ2-2-
generally 600–1000 Hz larger than for the corresponding or- C6H4PPh2)(PPh3)2]SbF6 (see above), even though the J(Pt-
tho-platinated complexes, probably as a consequence of the P) values are almost identical. Neither of the reported Pt–
four-membered ring in the latter. Since J(Pt-P) values for X P bond lengths fits well with the trend in J(Pt-P). Probably
= Br, NCS and for L = NEt3, PhNH2, SMe2 and tBuNC the range of Pt–P bond lengths is too small to allow mean-
were unavailable in the PtMe(dppe) series, we used for com- ingful conclusions except for ligands at the extremes of the
parison in Figure 4 the corresponding J(Pt-P) values from trans-influence series.
cis-[PtX(nBu)(PEt3)2] (X
[PtCl2(L)(PMe2Ph)] (L
=
Br, NCS),[75] trans-
NEt3, PhNH2),[76] trans-
Table 2. Pt–P bond lengths [Å] and coupling constants [Hz] for
neutral cis-[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] complexes
and cis-[PtL(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)]BF4 salts.
=
[PtCl2(SMe2)(PCy3)][77] and trans-[PtCl2(CNtBu)(PCy3)].[77]
Despite the obvious errors thereby introduced resulting
from different cis-ligands and different tertiary phosphanes,
the only marked discrepancy occurs for L = NEt3.[20] The
plot omits points corresponding to SeCN–, Ph3PO, Ph3PS,
SEt2, SPh2, toluidine (o-, m- and p-), THT, THF, DMSO,
MeCϵCMe and PhCϵCPh, for which literature J(Pt-P)
data could not be found.
X or L
trans to X or L
cis to X or L
d(Pt–P)
J(Pt-P)
d(Pt–P)
J(Pt-P)
Cl (2)
2.2539(8)
2.3169(8)
2.3095(11)
2.3126(13)
2.3174(6)
2.3324(7)
3392
2207
2132
2135
1803
1122
2.3350(8)
2.3225(8)
2.3294(11)
2.3229(12)
2.3129(6)
2.2903(7)
1990
1888
2004
2008
1981
2123
CN (11)
PPh2[-a4]-tol (34)
PPh3
C6F5 (45)
Me (43)
Table 2 shows a comparison of Pt-P coupling constants
and Pt–P bond lengths for the ortho-platinated complexes
whose structures have been determined in this work. It is
clear that the shortest Pt–P distances in the chelate ring
occurs for complex 2 (X = Cl), which has one of the highest
[a] Data for [Pt(κ2-2-C6H4PPh2)(PPh3)2]SbF6 from ref.[60]
Table 2 also shows that the Pt–P distances to the spec-
values of J(Pt-P). Conversely, the longest Pt–P distance is tator PPh2-4-tol ligand (PA) that is cis to X or L tend to
found in complex 43 (X = Me), which has one of the lowest decrease as the Pt–P distances trans to X or L increase;
J(Pt-P) values. Moreover, the position of C6F5– in the trans- again, the trend is clearest at the extremes. Except for X =
influence series above Cl– and below Me– is reflected in Cl (2) and Me (43), no corresponding trend in Pt-P coup-
both the Pt–P bond length and J(Pt-P) data. The data also ling constants is discernible. The bond-length trend is con-
agree in the placement of CN– above Cl– and below Me– sistent with earlier evidence for a poorly understood cis-
in the trans-influence series. However, the correspondence influence that is somewhat weaker than, and operates in the
between J(Pt-P) and Pt–P bond length data is not exact, opposite direction to, the trans-influence.[8,13,14,20,41,78–82]
since the Pt–P bond lengths for X = CN (11) and X = C6F5
We now consider some of the individual trends in the
(45) are equal, within experimental error, whereas the J(Pt- trans-influence series in more detail. Among the halides, the
P) value for 11 is ca. 400 Hz higher than for 45. The place- order Cl– Ͻ Br– Ͻ I– seems well established[5,6,83] and the
ment of PPh3 or PPh2-4-tol is problematic because of the apparently anomalous order Cl– Ͻ F– agrees with that de-
significantly different Pt–P bond lengths in the chelate ring rived from Pt-P coupling constants in [PtXL3]+ (L = PEt3,
3474
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 3467–3481

Bis(ortho-platinated) Triarylphosphane
PMe2Ph).[35] In contrast, the order F– Ͻ Cl– Ͻ Br– Ͻ I– is
derived from ν(Rh=C) values in planar rhodium(I) com-
plexes [RhXL(PiPr3)2] (L = C=CH2, CO).[84] This repre-
sents an example of the well-known dependence of the
placement of a ligand in the trans-influence series on the
physical method used to assess it.[5] Exceptionally, for the
three heavier halides, there is a perfect linear correlation
between J(Pt-PB) and δ(PB), but fluoride is anomalous.
The trans-influences of the neutral O-donor ligands THF
and Ph3PO are the lowest of all the ligands studied and, in
particular, are lower than those of the oxy anions, which
presumably are more covalently bound to the platinum(II)
atom. The order of the J(Pt-P) values for the oxy anions
parallels that of the dissociation constants of the free acids.
In agreement with earlier work,[9] the J(Pt-P) value for OH–
is considerably less than that for the oxy anions and places
this ligand close to neutral sulfur donors and SbPh3 in the
trans-influence series.
3. Conclusions
We have determined the Pt-P coupling constants for a
series of neutral and cationic chelate complexes, cis-
[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] and cis-[PtL(κ2-
C6H3-5-Me-2-PPh2)(PPh2-4-tol)]BF4. The J(Pt-P) values
for the phosphorus atom in the four-membered ring can be
ordered to provide an extensive trans-influence series that
is in fair agreement with those derived previously from mea-
surements of coupling constants of H, 13C or 31P to 195Pt
1
in different series of complexes. For four of the neutral com-
plexes there is a reasonable correlation between the J(Pt-P)
values and the corresponding Pt–P bond lengths. The Pt–
(PPh2-4-tol) distances in the determined structures are also
consistent with the existence of a cis-influence that runs op-
posite to the trans-influence.
4. Experimental Section
Of the neutral N-donors examined, acetonitrile and tri-
ethylamine have the lowest trans-influences, though both Abbreviations: DMSO = dimethyl sulfoxide; dppb = butane-1,4-
diylbis(diphenylphosphane), dppe = ethane-1,2-diylbis(diphenyl-
phosphane); dppen = ethene-1,2-diylbis(diphenylphosphane); dppf
are higher in the series than THF, because of the lower elec-
tronegativity of N. They are lower than ammonia, aniline
and o-toluidine, which do not differ greatly. p-Toluidine
comes above the other aromatic amines, possibly indicative
of stronger σ-donation and greater covalency in the Pt–N
bond, and this effect is even more marked with pyridine.
The order of trans-influence of the triarylpnicogens ob-
tained in this work, PPh2-4-tol Ͼ AsPh3 ≈ SbPh3, agrees
well with the order PPh3 Ͼ AsPh3 ≈ SbPh3 obtained from
the earlier 31P NMR study of [PtMe(L)(dppe)]+[9] and with
the results of X-ray crystallographic studies, e.g., of cis-
[PtBr2(SbPh3)(PPh3)][15] and [PtI3(L)]– (L = PPh3, AsPh3,
SbPh3).[3,4] Further, the conclusion from our work that
=
ferrocene-1,1Ј-diylbis(diphenylphosphane); en = ethylenedi-
amine; THF = tetrahydrofuran; THT = tetrahydrothiophene.
General Procedures: Experiments involving organolithium reagents
were performed under dry argon with the use of standard Schlenk
techniques. Diethyl ether, tetrahydrofuran, n-pentane and n-hexane
were dried with sodium/benzophenone and toluene with sodium
prior to use. IR spectra were measured as KBr discs or as hexachlo-
robutadiene or Nujol mulls between NaCl plates, and FIR spectra
as polythene discs with a Perkin–Elmer Spectrum 2000 FT spec-
trometer. 1H (200 MHz) and 13C (50 MHz) NMR spectra were
measured with a Varian Gemini 2000 spectrometer, and 19F
(188.2 MHz), 31P (80.96 MHz) and 195Pt (42.83 MHz) NMR spec-
AsPh3 and S-DMSO have almost equal trans-influences, tra with a Varian XL-200E spectrometer. 1H and 13C NMR spectra
are internally referenced to residual solvent signals, 19F internally
both being higher in the series than SMe2, is supported by
to CFCl3, 31P to external 85% H3PO4 and 195Pt externally refer-
a comparison of the Pt–Cl distances in cis-[PtCl2(SMe2)(L)]
enced to Na2PtCl6/D2O. 31P NMR spectroscopic data for the cis-
(L = AsPh3, DMSO).[17]
complexes are listed in Table 1. Quoted multiplicities exclude 195Pt
As noted above, C6F5 has a higher trans-influence than
Cl, and this confirms the trend evident from both the
satellites. Microanalyses were performed by the Microanalytical
Unit at the Research School of Chemistry, Australian National
University. Mass spectra were obtained with a VG ZAB-2SEQ
spectrometer using NOPE as matrix (FAB), an HP 5970 MSD
Pt–P bond lengths and coupling constants in cis-
[PtCl(C6F5)(dppe)].[71] The smaller trans-influence of C6F5
relative to that of C6H5 evident from our data also emerges
from a comparison of the Pt-P coupling constants trans to
spectrometer (ES) or Bruker Biflex II spectrometer (MALDI). The
complex [Pt(κ2-C6H3-5-Me-2-PPh2)2] (1) was prepared as described
the σ-carbon-bonded group in cis-[PtCl(R)(dppe)] [R = Ph previously.[21]
(1613 Hz);[9] R = C6F5 (2251 Hz)[71]], although it should be
noted that the Pt-P coupling constants trans to Cl also dif-
X-ray Crystallography: Data were collected at 200 K with a Non-
ius-Kappa CCD diffractometer using graphite-monochromated
fer substantially in the opposite sense in these two com-
Mo-Kα radiation (λ = 0.71073 Å) and were measured by means of
pounds (4165 Hz, 3720 Hz, respectively). The reduction of COLLECT.[87] Selected crystal data and details of data collection
trans-influence, as assessed by 31P NMR spectroscopy,
and structural refinement are in Table 3. The intensities of the re-
flections were measured, and the data were reduced by use of the
caused by complete replacement of all the hydrogen atoms
programs Denzo and Scalepack.[88] The structures of complexes
of C6H5 by fluorine is similar to, though somewhat larger
trans-6, 2, 11, and 43 were solved by heavy-atom Patterson methods
than, that observed in going from CH3 to CF3.[9]
(PATTY), expanded by standard Fourier synthesis (DIRDIF 92[89]
Finally, according to the J(Pt-P) data, the alkynes
for 2, 11 and 43, DIRDIF 96[90] for trans-6), and refined on F with
RCϵCR (R = Me, Ph) have relatively low trans-influences,
being slightly above Cl– and in about the same position as
NCO– in the series, in agreement with conclusions based on
1J(Pt-CH3) and 2J(Pt-CH3) data for ligands attached to the
fragment trans-[PtMe(PMe2Ph)2].[85,86]
use of TEXSAN[91] for 2, 11, 43, or CRYSTALS[92] for trans-6. The
structures of complexes 34 and 45 were solved by direct methods
(SIR 92)[93] and refined on F with use of CRYSTALS.[92] Although
the three aromatic rings of the PPh2-4-tol ligand were clearly ob-
served in the structures of trans-6 and 45, the 4-tolyl group and
Eur. J. Inorg. Chem. 2008, 3467–3481
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3475

M. A. Bennett, S. K. Bhargava, S. H. Privér, A. C. Willis
FULL PAPER
Table 3. Crystal and structure refinement data for trans-[Pt(κ1-OCOCF3)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (trans-6), cis-[PtX(κ2-C6H3-
5-Me-2-PPh2)(PPh2-4-tol)] [X = Cl (2), CN (11), CH3 (43), C6F5 (45)] and cis-[Pt(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)2]BF4 (34).
trans-6
2
11
Empirical formula
Formula mass
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C40H33F3O2P2Pt·0.5C5H12
C38H33ClP2Pt·0.5C6H6
821.23
C39H33NP2Pt·0.5C6H6
811.79
895.81
triclinic
triclinic
triclinic
¯
¯
¯
P1
P1
P1
10.6396(2)
10.8280(2)
17.4628(3)
104.755(1)
96.503(1)
100.138(1)
1888.50(6)
2
11.0071(2)
12.6657(3)
13.5217(3)
72.114(1)
75.622(1)
77.984(1)
1719.91(7)
2
11.1369(3)
12.6425(3)
13.5054(4)
72.422(2)
75.035(2)
77.359(2)
1730.67(9)
2
α [°]
β [°]
γ [°]
V [Å3]
Z
Colour, habit
Crystal size [mm]
ρcalcd. [g cm–3]
µ [mm–1]
Total reflections
Unique reflections
Used reflections
Number of parameters
R (used reflections)
Goodness of fit
wR (used reflections)
ρmax, ρmin [eÅ–3]
colourless, block
0.30ϫ0.28ϫ0.19
1.575
3.850
38531
8648 (Rint = 0.040)
7029 [IϾ3σ(I)]
457
0.0261
1.0682
colourless, block
0.20ϫ0.18ϫ0.10
1.586
4.262
44004
10039 (Rint = 0.043)
8674 [IϾ2σ(I)]
406
0.0359
1.23
colourless, block
0.20ϫ0.13ϫ0.12
1.558
4.161
33574
7977 (Rint = 0.037)
7240 [IϾ2σ(I)]
415
0.0302
1.32
0.0286
0.95, –1.06
0.0355
0.38, –0.38
0.0336
–1.06, –1.13
34
43
45
Empirical formula
Formula mass
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C57H50BF4P3Pt·CH2Cl2
1194.77
monoclinic
P21/n
19.1683(2)
15.2202(1)
20.3797(2)
90
117.5968(4)
90
C39H36P2Pt·0.5C6H6
800.81
C44H33F5P2Pt
913.77
monoclinic
P21/n
14.5239(2)
12.5382(1)
20.6832(2)
90
90.6982(6)
90
triclinic
¯
P1
11.1602(2)
12.6761(2)
13.4685(2)
72.3105(7)
76.1296(7)
77.1573(7)
1739.18(5)
2
α [°]
β [°]
γ [°]
V [Å3]
5269.24(9)
4
3766.21(7)
4
Z
Colour, habit
Crystal size [mm]
ρcalcd. [g cm–3]
µ [mm–1]
Total reflections
Unique reflections
Used reflections
Number of parameters
R (used reflections)
Goodness of fit
wR (used reflections)
ρmax, ρmin [eÅ–3]
colourless, plate
0.32ϫ0.20ϫ0.05
1.506
2.896
128697
15402 (Rint = 0.054)
7094 [IϾ3σ(I)]
651
0.0280
1.01
colourless, plate
0.25ϫ0.19ϫ0.12
1.529
4.138
45235
10155 (Rint = 0.040)
9331 [IϾ2σ(I)]
406
0.0305
1.43
colourless, block
0.43ϫ0.28ϫ0.15
1.611
3.866
69288
8630 (Rint = 0.052)
6642 [IϾ3σ(I)]
479
0.0190
1.10
0.0202
0.90, –0.60
0.0353
0.87, –1.46
0.0218
1.15, –1.03
one phenyl ring were disordered, as indicated by the presence of
partly occupied methyl groups on C(23) and C(36) in trans-6, and
on C(214) and C(224) in 45. The relative occupancies of the methyl
groups in both cases were refined. Similar behaviour was evident
in the 4-tolyl groups of the ligand trans to P(1) in the structure of
complex 34 and, in one case, the two images were sufficiently sepa-
rated to allow modelling of each component and refinement of the
relative populations, with restrains on distances, angles and planar-
ity. Hydrogen atoms were generally included at idealised positions
and ride on the atom to which they are bonded. Methyl groups
were oriented to best-fit peaks observed in difference electron-den-
sity maps. CCDC-683243 (for 45), -683244 (for 34), -683245 (for
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Preparations
cis-[PtCl(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (2): HCl (constant
boiling aqueous solution, 98.8 µL, 0.548 mmol) in THF (4 mL) was
added to a solution of 1 (409 mg, 0.548 mmol) in THF (10 mL).
After the mixture had been stirred for 10 min, the solvent was re-
moved in vacuo. The off-white solid was dissolved in toluene, and
the solution was transferred to a silica gel column. The fraction
trans-6), -683246 (for 2), -683247 (for 11), and -683248 (for 43) that eluted with toluene was concentrated to ca. 1 mL volume, and
3476 Eur. J. Inorg. Chem. 2008, 3467–3481
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Bis(ortho-platinated) Triarylphosphane
n-hexane was added. The precipitated white solid was washed with
n-hexane and dried in vacuo. The yield of 2 was 401 mg (93%).1 H
(arom C=C str), 726 (C–H def) cm–1. ES-MS: m/z = 875 [M]+.
C38H33IP2Pt·0.5C6H5CH3 (919.68): calcd. C 54.20, H 4.06, P 6.74;
NMR (CDCl3): δ = 2.33 (s, 3 H, Me), 2.34 (s, 3 H, Me), 6.8–7.8 found C 54.09, H 4.11, P 6.63. The presence of toluene was con-
1
(m, 27 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ = –3944 [dd, firmed by the presence of a small singlet at δ = 2.35 ppm in the H
J(Pt-P) = 1990, 3391 Hz] ppm. IR (KBr): ν = 3052, 2916 cm–1 (C–
NMR spectrum.
˜
H str), 1569 (arom C=C str), 725 (C–H def) cm–1. FIR (polythene):
cis-[Pt(κN-N3)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (12): A solu-
tion of 2 (50 mg, 0.068 mmol) in CH2Cl2 (3 mL) was treated with
NaN3 (12 mg, 0.180 mmol) in methanol (3 mL), and the mixture
was stirred for 1 h. The solvent was removed in vacuo, and the
residue was extracted with toluene (5 mL). The extract was filtered,
and its volume was reduced to about half under reduced pressure.
The white solid that precipitated on addition of n-pentane was re-
dissolved in CH2Cl2 and re-precipitated with n-pentane. It was sep-
arated by filtration, washed with n-pentane, and dried in vacuo.
ν
=
314 (Pt–Cl str) cm–1. ES-MS: m/z
=
782 [M]+.
˜
C38H33ClP2Pt·0.7C6H5CH3 (846.66): calcd. C 60.86, H 4.60, P 7.32;
found C 60.87, H 4.60, P 7.79. The presence of toluene was con-
firmed by the observation of a singlet at δ = 2.35 ppm in the 1H
NMR spectrum. X-ray quality crystals were grown from benzene/
n-pentane. Slow cis Ǟ trans isomerisation occurred when solutions
of 2 were set aside. After 24 h, ca. 10% of trans-2 was observed by
31P NMR spectroscopy. Under CO, the isomerisation was quantita-
tive after 30 min. 31P NMR (CDCl3): δ = 24.4 [d, J(P-P) = 447 Hz,
J(Pt-P) = 3121 Hz], –61.8 [d, J(P-P) = 447 Hz, J(Pt-P) = 2196 Hz]
ppm.
cis-[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] [X = Br (3), ONO2
(5), OCOCF3 (6)]: These were prepared similarly to 2 by treatment
of 1 (409 mg, 0.548 mmol) with constant boiling HBr (93.7 µL),
constant boiling HNO3 (51 µL) or neat CF3COOH (42 µL), respec-
tively, and isolated as white solids in yields of 75–90%.
1
The yield was 47 mg (94%). H NMR (CDCl3): δ = 2.34 (s, 3 H,
Me), 2.35 (s, 3 H, Me), 6.8–8.2 (m, 27 H, arom) ppm. IR (KBr): ν
˜
= 3051, 2918 cm–1 (C–H str), 2043 (N=N=N str), 1570 (arom C=C
str), 725 (C–H def) cm–1. FAB-MS: m/z (%) = 746 [M – N3]+.
C38H33N3P2Pt (788.73): calcd. C 57.87, H 4.22, N 5.33, P 7.85;
found C 57.98, H 4.34, N 5.18, P 8.18.
cis-[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] [X = NCO (13), NCS/
SCN (14), SeCN (15)]: These were prepared similarly to 12 with
use of NaOCN (12 mg, 0.180 mmol), NaSCN (15 mg, 0.180 mmol)
and KSeCN (25 mg, 0.173 mmol), respectively. The complexes 13
and 14 were obtained almost quantitatively as white solids; com-
plex 15 was obtained as a white solid (49 mg) containing about
25% of the desired product, 10% of the cyanido complex 11, and
other unidentified products of decomposition.
3: 1H NMR (CDCl3): δ = 1.53 (br. s, H2O), 2.32 (s, 3 H, Me), 2.33
(s, 3 H, Me), 6.7–8.4 (m, 27 H, arom) ppm. 195Pt{1H} NMR
(CDCl3): δ = –3787 [dd, J(Pt-P) = 1999, 3666 Hz] ppm. IR (KBr):
ν = 3435 cm–1 (O–H str), 3051, 2919 (C–H str), 1570 (arom C=C
˜
str), 725 (C–H def) cm–1. ES-MS: m/z
=
827 [M]+.
C38H33BrP2Pt·H2O (844.63): calcd. C 54.04, H 4.18, P 7.33; found
C 54.45, H 4.06, P 7.35.
13: 1H NMR (CDCl3): δ = 2.33 (s, 3 H, Me), 2.34 (s, 3 H, Me),
6.8–7.8 (m, 27 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ = –3956
5: 1H NMR (CDCl3): δ = 2.30 (s, 3 H, Me), 2.32 (s, 3 H, Me), 6.8–
7.6 (m, 27 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ = –4108
[dd, J(Pt-P) = 1940, 3232 Hz] ppm. IR (KBr): ν = 3050, 2917 cm–1
˜
[dd, J(Pt-P) = 2067, 3574 Hz] ppm. IR (hexachlorobutadiene): ν =
˜
(C–H str), 2214, 2170 (CϵN str), 1570 (arom C=C str), 725 (C–H
def) cm–1. ES-MS: m/z = 787 [M]+. C39H33NOP2Pt (788.72): calcd.
C 59.39, H 4.22, N 1.78, P 7.85; found C 59.09, H 4.35, N 1.76, P
8.22.
14: 1:1 mixture of κN and κS isomers. 1H NMR (CDCl3): δ = 2.34
(br. s, 12 H, Me), 6.7–8.0 (m, 54 H, arom) ppm. 195Pt{1H} NMR
(CDCl3): δ = –3747 [dd, J(Pt-P) = 2037, 2953 Hz] ppm (κS-SCN);
3052, 2918 (C–H str), 1480, 1435, 1272, 1098 [ν(ONO2)] cm–1. ES-
MS: m/z = 746 [M – NO3]+. C38H33NO3P2Pt·0.3C6H5CH3 (836.35):
calcd. C 57.71, H 4.28, N 1.67, P 7.38; found C 57.72, H 4.36, N
1.61, P 7.73. The presence of toluene was confirmed by the pres-
ence of a small peak at δ = 2.35 ppm in the 1H NMR spectrum.
When a solution of 5 in C6D6 was set aside for 24 h, the trans-
isomer was formed quantitatively, as shown by 31P NMR spec-
troscopy. 31P NMR (C6D6): δ = 25.4 [d, J(P-P) = 428 Hz, J(Pt-P)
= 3284 Hz], –52.6 [d, J(P-P) = 428 Hz, J(Pt-P) = 2337 Hz] ppm.
–3801 [dd, J(Pt-P) = 2180, 3085 Hz] ppm (κN-NCS). IR (KBr): ν
˜
= 3052, 2917 cm–1 (C–H str), 2212, 2093 (C=N str), 1570 (arom
C=C str), 725 (C–H def) cm–1. IR (CHCl ): ν = 3058, 2924 cm–1
˜
3
6: 1H NMR (CDCl3): δ = 2.20 (s, 3 H, Me), 2.22 (s, 3 H, Me), 6.6–
7.9 (m, 27 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ = –4117
(C–H str), 2112 (C=N str), 1571 (arom C=C str) cm–1. ES-MS: m/z
= 745 [M – CNS]+. C39H33NP2PtS (804.79): calcd. C 58.20, H 4.13,
N 1.74, P 7.70; found C 58.01, H 4.28, N 1.79, P 7.94.
[dd, J(Pt-P) = 2037, 3507 Hz] ppm. IR (nujol): ν = 1699 cm–1 (C=O
˜
str), 1571 (arom C=C str) 1409, 1197 (C=O, C–O str), 1134,
1098 cm–1. ES-MS: m/z = 859 [M]+. C40H33F3O2P2Pt (859.72):
calcd. C 55.88, H 3.87, P 7.21; found C 55.81, H 4.09, P 7.03. When
a solution of 6 in C6D6 was set aside for 24 h, or stirred under CO
for 30 min, the trans-isomer was formed quantitatively, as shown
by 31P NMR spectroscopy. 31P NMR (C6D6): δ = 25.9 [d, J(P-P)
= 441 Hz, J(Pt-P) = 3249 Hz], –52.7 [d, J(P-P) = 441 Hz, J(Pt-P)
= 2361 Hz] ppm. X-ray quality crystals were obtained from ben-
zene/n-pentane.
15: FAB-MS: m/z = 852 [M]+.
cis-[Pt(OCOMe)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (9): Silver
acetate (11 mg, 0.065 mmol) was added to a solution of 2 (50 mg,
0.068 mmol) in CHCl3 (0.5 mL). The mixture was stirred in the
dark for 15 min, and the precipitated AgCl was removed by centri-
fugation. The supernatant was concentrated to a small volume un-
der reduced pressure, and n-pentane was added to precipitate a
white solid. This was re-dissolved in CH2Cl2, re-precipitated with
n-pentane, washed with n-pentane and dried in vacuo to give com-
cis-[PtI(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (4): A solution of 2
(100 mg, 0.128 mmol) in acetone (10 mL) was treated with NaI
(57 mg, 0.380 mmol), and the mixture was stirred for 10 min. The
solvent was removed in vacuo, and the residue was extracted with
toluene. Chromatography on silica gel and workup as described for
2 gave complex 4 as a white solid (93 mg, 83%). 1H NMR (CDCl3):
δ = 2.33 (s, 3 H, Me), 2.34 (s, 3 H, Me), 6.7–8.5 (m, 27 H, arom)
1
plex 9 as a colourless solid (43 mg, 83%). H NMR (CDCl3): δ =
2.30 (s, 3 H, Me), 2.31 (s, 3 H, Me), 2.33 (s, 3 H, Me), 6.7–8.0 (m,
27 H, arom) ppm. IR (hexachlorobutadiene): ν = 3054, 2921 (C–
˜
H str), 1628 (C=O str), 1311 (C–O str) cm–1. FAB-MS: m/z = 745
[M – OCOMe]+.
cis-[Pt(OCOPh)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (10): This
ppm. 195Pt{1H} NMR (CDCl3): δ = –4064 [dd, J(Pt-P) = 2009, was prepared similarly to 9, with use of silver benzoate (15 mg,
3200 Hz] ppm. IR (KBr): ν = 3051, 2914 cm–1 (C–H str), 1568 0.065 mmol). The product was precipitated with n-hexane instead
˜
Eur. J. Inorg. Chem. 2008, 3467–3481
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3477

M. A. Bennett, S. K. Bhargava, S. H. Privér, A. C. Willis
FULL PAPER
of n-pentane. The yield was 50 mg (91%). H NMR (CDCl3): δ =
1
centrifugation, and the supernatant liquid was concentrated. Ad-
2.31 (s, 3 H, Me), 2.32 (s, 3 H, Me), 6.6–8.0 (m, 32 H, arom) ppm. dition of diethyl ether precipitated a white solid, which was purified
IR (hexachlorobutadiene): ν = 3056, 2915 (C–H str), 1712, 1633
by dissolution in CH2Cl2 and re-precipitated with diethyl ether. The
˜
(C=O str), 1336 (C–O str) cm–1. ES-MS: m/z = 867 [M]+. solid was washed with diethyl ether and n-hexane, and dried in
1
C45H38O2P2Pt (867.82): calcd. C 62.28, H 4.41, P 7.14; found C
62.48, H 4.69, P 7.37. The trans-isomer was formed quantitatively
in C6D6 after 24 h. 31P NMR (C6D6): δ = 27.4 [d, J(P-P) = 455 Hz,
vacuo. The yield of 34 was 66 mg (93%). H NMR (CDCl3): δ =
1.56 (br. s, 2 H, H2O), 1.75 (s, 3 H, Me), 2.32 (s, 3 H, Me), 2.37 (s,
3 H, Me), 6.4–7.8 (m, 41 H, arom) ppm. 195Pt{1H} NMR (CDCl3):
J(Pt-P) = 3257 Hz], –53.0 [d, J(P-P) = 455 Hz, J(Pt-P) = 2514 Hz] δ = –4377 [ddd, J(Pt-P) = 2007, 2135, 2846 Hz] ppm. MALDI-MS:
ppm.
m/z = 1021 [M – BF4]+. C57H50BF4P3Pt·H2O (1127.85): calcd. C
60.70, H 4.65, P 8.24; found C 60.35, H 4.64, P 8.42. X-ray quality
crystals were grown from CH2Cl2/benzene/n-pentane.
The following complexes cis-[PtL(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-
tol)]BF4 were prepared as white solids similarly to 34 on the same
scale.
L = AsPh3 (35): 71 mg (97%) from AsPh3 (20 mg, 0.065 mmol). 1H
NMR (CDCl3): δ = 1.55 (br. s, 4 H, H2O), 1.76 (s, 3 H, Me), 2.32
(s, 3 H, Me), 6.4–7.7 (m, 42 H, arom) ppm. MALDI-MS: m/z =
1051 [M – BF4]+. C56H48AsBF4P2Pt·2H2O (1175.79): calcd. C
57.21, H 4.46, P 5.27; found C 57.25, H 4.35, P 5.66.
L = SbPh3 (36): 73 mg (96%) from SbPh3 (23 mg, 0.065 mmol). 1H
NMR (CDCl3): δ = 1.51 (br. s, 2 H, H2O), 1.72 (s, 3 H, Me), 2.21
(s, 3 H, Me), 6.5–7.6 (m, 42 H, arom) ppm. MALDI-MS: m/z =
1097 [M – BF4]+. C56H48BF4P2PtSb·H2O (1204.59): calcd. C 55.84,
H 4.18, P 5.14; found C 55.37, H 4.15, P 5.32.
cis-[Pt(OH)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (8): Freshly pre-
pared, moist silver oxide (ca. 150 mg, large excess) was added to a
solution of 2 (50 mg, 0.063 mmol) in CH2Cl2 (2 mL), and the mix-
ture was stirred in the dark for 3 d. Workup as for 9 gave a white
solid (48 mg) consisting mainly of 8 contaminated with ca. 5% of
2. Selected 1H NMR (CD2Cl2) data: δ = 1.25 (br. s, 1 H, OH), 2.30
(s, 3 H, Me), 2.33 (s, 3 H, Me), 6.8–8.2 (m, 27 H, arom) ppm.
195Pt{1H} NMR (CDCl3): δ = –4205 [dd, J(Pt-P) = 2008, 2803 Hz]
ppm. IR (Nujol): ν = 3657 cm–1 (O–H str), 3048 (C–H str), 1570
˜
(arom C=C str), 1027 (O–H def), 725 (C–H def) cm–1. ES-MS: m/z
= 763 [M – H]+.
cis-[PtX(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] [X = F (7), CN (11)]:
These were prepared similarly to 8 from 2 (50 mg, 0.063 mmol) in
dry CH2Cl2 and AgF (9 mg, 0.071 mmol) or AgCN (9 mg,
0.067 mmol), respectively, the mixtures being stirred for 3 d in the
case of 7 and 3 h in the case of 11. Workup as for complex 9 gave
7 (33 mg, 68%) and 11 (45 mg, 91%) as white solids.
L = Ph3PO (18): 71 mg (97%) from Ph3PO (20 mg, 0.065 mmol).
1H NMR (CDCl3): δ = 1.78 (s, 3 H, Me), 2.28 (s, 3 H, Me), 6.7–
7.8 (m, 42 H, arom) ppm. FAB-MS: m/z = 1042 [M – BF4]+.
7: 1H NMR (CD2Cl2): δ = 2.32 (s, 3 H, Me), 2.33 (s, 3 H, Me),
6.6–7.7 (m, 27 H, arom) ppm. 19F NMR (CD2Cl2): δ –285.1 [dd,
J(P-F) = 26.1, 162.1 Hz, J(Pt-F) = 241 Hz] ppm. 195Pt{1H} NMR
(CD2Cl2): δ = –4342 [ddd, J(Pt-P) = 1999, 3376 Hz, J(Pt-F) =
235 Hz] ppm. FAB-MS: m/z = 746 [M – F]+. C38H33FP2Pt (765.71):
calcd. C 59.61, H 4.34, P 8.09; found C 59.23, H 4.57, P 8.09.
L = Ph3PS (32): 53 mg (74%) from Ph3PS (19 mg, 0.064 mmol).
1H NMR (CDCl3): δ = 1.50 (br. s, 2 H, H2O), 1.75 (s, 3 H, Me),
2.25 (s, 3 H, Me), 6.7–7.8 (m, 42 H, arom) ppm. FAB-MS: m/z =
1042 [M – BF4]+. C56H48BF4P3PtS·H2O (1145.88): calcd. C 58.70,
H 4.40, P 8.11; found C 58.76, H 4.41, P 8.40.
11: 1H NMR (CDCl3): δ = 1.51 (br. s, 2 H, H2O), 2.33 (s, 3 H,
Me), 2.35 (s, 3 H, Me), 6.8–8.3 (m, 27 H, arom) ppm. IR (KBr): ν
L = Ph3PSe (33): 71 mg (97%) from Ph3PSe (20 mg, 0.065 mmol).
1H NMR (CDCl3): δ = 1.79 (s, 3 H, Me), 2.32 (s, 3 H, Me), 6.8–
7.7 (m, 42 H, arom) ppm. ES-MS: m/z = 1087 [M – BF4]+.
C56H48BF4P3PtSe (1174.76): calcd. C 57.26, H 4.12, P 7.91; found
C 57.07, H 4.18, P 7.89.
˜
= 3438 cm–1 (O–H str), 3053, 2918 (C–H str), 2128 (CϵN str), 1571
(arom C=C str), 725 (C–H def) cm–1. MALDI-MS: m/z = 772
[M]+. C39H33NP2Pt·H2O (790.75): calcd. C 59.24, H 4.46, N 1.77,
P 7.83; found C 59.19, H 4.45, N 1.77, P 7.92. X-ray quality crystals
were grown from benzene/n-pentane.
L = P(OPh)3 (37): 61 mg (83%) of off-white solid obtained by use
1
of one drop of P(OPh)3. H NMR (CDCl3): δ = 2.31 (s, 3 H, Me),
cis-[Pt(κN-NO2)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (16): A solu-
tion of cis-[Pt(THF)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)]BF4 (17)
was generated in situ by treatment of a solution of 2 (50 mg,
0.063 mmol) in CHCl3 (0.5 mL) containing a drop of THF with
AgBF4 (12.4 mg, 0.063 mmol). The AgCl was removed by centrifu-
gation, and the solution was treated with a solution of NaNO2
(13 mg, 0.188 mmol) in methanol (4 mL). The solvents were re-
moved in vacuo, and the residue was extracted with CH2Cl2. Re-
peated attempts to isolate a solid by concentration to a small vol-
ume and addition of n-hexane gave an orange oil. Finally, the oil
was extracted with several portions of n-hexane, and the extracts
were concentrated to dryness to give 16 as an off-white solid
2.34 (s, 3 H, Me), 6.6–8.0 (m, 42 H, arom) ppm. ES-MS: m/z =
1056 [M – BF4]+.
L = P(OMe)3 (38): White solid (59 mg) from P(OMe)3 (7.5 µL,
0.063 mmol). The 31P NMR spectrum showed this to contain ca.
30% of the bis(phosphite) complex arising from displacement of
the PPh2-4-tol ligand, together with smaller amounts of unidenti-
1
fied impurities. Selected H NMR (CDCl3) data: δ = 2.36 (s, 3 H,
tolyl Me), 2.37 (s, 3 H, tolyl Me), 3.56 [d, J(P-H) = 12.3 Hz, 9 H,
3 OMe], 6.8–7.6 (m, 27 H, arom) ppm. ES-MS: m/z = 870 [M –
BF4]+.
1
L = SMe2 (27): 55 mg (96%) by use of 1 drop of SMe2. H NMR
1
(47 mg, 92%). H NMR (CDCl3): δ = 2.26 (s, 3 H, Me), 2.32 (s, 3
(CDCl3): δ = 1.56 (br. s, 1 H, H2O), 2.31 (s, 3 H, tolyl Me), 2.32,
2.35 [2 s, 6 H, SMe2 J(Pt-H) = 40.6 Hz], 2.34 (s, 3 H, tolyl Me),
6.8–8.0 (m, 42 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ = –3675
[dd, J(Pt-P) = 2007, 2840 Hz] ppm. FAB-MS: m/z = 808 [M –
BF4]+. C40H39BF4P2PtS·0.5H2O (904.65): calcd. C 53.11, H 4.46,
P 6.85; found C 53.29, H 4.43, P 7.23.
H, Me), 6.8–8.0 (m, 27 H, arom) ppm. IR (KBr): ν = 3051, 2949,
˜
2918 (C–H str), 1570 (arom C=C str), 1384, 1331 (NO2 str), 817
(NO2 def), 725 (C–H def) cm–1. FAB-MS: m/z = 746 [M – NO2]+.
C38H33NO2P2Pt (792.71): calcd. C 57.58, H 4.20, N 1.77, P 7.81;
found C 57.89, H 4.48, N 1.78, P 7.83.
cis-[Pt(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)2]BF4 (34):
A
stirred
L = THT (30): Addition of 1 drop of THT gave a white solid
solution containing 2 (50 mg, 0.063 mmol) and PPh2-4-tol (18 mg,
0.065 mmol) in CHCl3 was treated with AgBF4 (12.4 mg,
0.063 mmol). After 5 min, the precipitated AgCl was removed by
from which adhering THT could not be removed, even by repeated
washing with diethyl ether or drying in vacuo. H NMR (CDCl3):
δ = 1.50 (br. m, 4 H, CH2CH2) 2.23 (s, 3 H, Me), 2.35 (s, 3 H, Me),
1
3478
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 3467–3481

Bis(ortho-platinated) Triarylphosphane
2.85 [br. m, 4 H, CH2SCH2, J(Pt-H) ≈ 40 Hz], 6.7–7.5 (m, 27 H, 40 Hz, 2 H, NH2], 6.5–7.8 (m, 31 H, arom) ppm. 195Pt{1H} NMR
arom) ppm.
(CDCl3): δ = –3884 [dd, J(Pt-P) = 2058, 3035 Hz] ppm. ES-MS:
m/z = 854 [M – BF4]+.
L = CO (39): Carbon monoxide was bubbled through a solution
of 2 in CHCl3 or CDCl3 to which AgBF4 (12.4 mg, 0.063 mmol)
had been added. After 5 min, a precipitate of AgCl had formed.
Attempts to isolate 39 from the supernatant liquid failed, so spec-
troscopic data were obtained in situ. 195Pt{1H} NMR (CDCl3): δ
–3631 [dd, J(Pt-P) = 1832, 2599 Hz] ppm.
L = p-MeC6H4NH2 (24): Red solid (54 mg, 92%) from freshly sub-
limed p-toluidine (7 mg, 0.065 mmol). 1H NMR (CDCl3): δ = 2.24
(s, 3 H, Me), 2.32 (s, 6 H, 2 Me), 6.06 [br. s, J(Pt-H) ≈ 43 Hz, 2 H,
NH2], 6.6–7.6 (m, 31 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ
= –3882 [dd, J(Pt-P) = 2075, 3016 Hz] ppm. ES-MS: m/z = 854
[M – BF4]+.
L = MeCN (26): A solution of 2 in C6D6 or CDCl3 containing a
drop of acetonitrile was treated with AgBF4 (12.4 mg, 0.063 mmol).
The 31P NMR spectrum was acquired after 30 min. The product
decomposed on attempted isolation. After 24 h in solution, com-
plete isomerisation to the trans-isomer had occurred. 31P NMR
(C6D6): δ = 23.7 [d, J(P-P) = 392 Hz, J(Pt-P) = 3005 Hz], –59.3
[J(P-P) = 392 Hz, J(Pt-P) = 2088 Hz] ppm.
L = C5H5N (25): Off-white solid (51 mg, 88%) from 1 drop of
pyridine. 1H NMR (CDCl3): δ = 2.19 (s, 3 H, Me), 2.31 (s, 3 H,
Me), 6.3–7.6 (m, 27 H, arom), 7.93 [dd, J(H-H) = 1.5, 7.7 Hz, 2
H, m-H of C5H5N], 8.39 [br. m, J(Pt-H) ≈ 25 Hz, 2 H, o-H of
C5H5N], 8.75 [dd, J(H-H) = 1.5, 6.3 Hz, 1 H, p-H of C5H5N] ppm.
FAB-MS: m/z = 825 [M – BF4]+.
The corresponding, similarly generated complexes containing L =
SEt2 (28), SPh2 (29), DMSO (31), MeCϵCMe (41), PhCϵCPh (42)
and THF (17) also could not be isolated. Their 31P NMR spectra
were obtained in situ.
L = tBuNC (40): Off-white solid (41 mg, 71%) from 1 drop of tert-
butyl isocyanide. 1H NMR (CDCl3): δ = 1.34 (s, 9 H, tBu), 2.39 (s,
3 H, tolyl Me), 2.40 (s, 3 H, tolyl Me), 6.8–7.7 (m, 27 H, arom)
ppm. 195Pt{1H} NMR (CDCl3): δ = –3552 [q of 1:1:1 t, J(Pt-P) =
1844, 2056 Hz, J(Pt-N) = 80.2 Hz] ppm. IR (hexachlorobutadiene):
L = NH3 (19): AgBF4 (12.4 mg, 0.063 mmol) was added to a solu-
tion of 2 (50 mg, 0.063 mmol) in CHCl3 (0.5 mL) containing 1 drop
of THF. The precipitated AgCl was removed by centrifugation, and
the supernatant liquid, after being decanted, was treated with 1
drop of concentrated aqueous NH3. The solution was concentrated
to a small volume under reduced pressure. Addition of diethyl ether
precipitated a white solid, which was purified by dissolution in
CH2Cl2 and re-precipitation with diethyl ether. The solid was
washed with n-pentane and dried in vacuo. The yield was 43 mg
(80%). 1H NMR (CDCl3): δ = 2.32 (s, 6 H, 2 Me), 3.24 [br. s, 3 H,
NH3, J(Pt-H) ≈ 40 Hz], 6.8–7.8 (m, 27 H, arom) ppm. FAB-MS:
m/z = 764 [M – BF4]+. C38H36BF4NP2Pt (850.54): calcd. C 53.66,
H 4.27, N 1.65, P 7.28; found C 53.45, H 4.31, N 1.47, P 7.46.
ν = 3047, 2981, 2915 (C–H str), 2212 (CϵN str), 1566 (arom C=C
˜
str), 725 (C–H def) cm–1. ES-MS: m/z = 829 [M – BF4]+.
cis-[PtMe(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (43): Under dry ar-
gon, a stirred solution of 2 (80 mg, 0.102 mmol) in THF (5 mL)
was treated dropwise with methyllithium (1.6  in diethyl ether,
70 µL, 0.120 mmol). The mixture was stirred at room temperature
for 1 h, the solvent was removed in vacuo, and the compound was
extracted from the residue with CH2Cl2 (5 mL). Concentration to
about half volume and addition of methanol gave 43 as a colourless
solid (59 mg, 76%). 1H NMR (CDCl3): δ = 0.95 [t, J(P-H) =
7.1 Hz, J(Pt-H) = 74.7 Hz, 3 H, Pt-Me], 2.31 (s, 3 H, tolyl Me),
2.33 (s, 3 H, tolyl Me), 6.9–8.0 (m, 27 H, arom) ppm. 195Pt{1H}
NMR (CDCl3): δ = –4156 [dd, J(Pt-P) = 1127, 2132 Hz] ppm. IR
L = NEt3 (20): The same procedure was used as for complex 19,
with 1 drop of NEt3 in place of NH3. Addition of diethyl ether
gave a semi-solid that was purified by repeated washing with diethyl
ether and n-pentane, and drying in vacuo. The yield was 51 mg
(94%). 1H NMR (CDCl3): δ = 1.29 [t, J(H-H) = 7.3 Hz, 9 H,
MeCH2N], 2.06 (s, 3 H, tolyl Me), 2.28 (s, 3 H, tolyl Me), 3.03 (br.
d, 6 H, MeCH2N), 6.7–8.7 (m, 27 H, arom) ppm. 195Pt{1H} NMR
(CDCl3): δ = –4171 [dd, J(Pt-P) = 1921, 3304 Hz] ppm. ES-MS:
m/z = 745 [M – NEt3 – BF4]+. C44H44BF4NP2Pt (930.67): calcd. C
56.54, H 5.18, N 1.50, P 6.63; found C 52.98, H 4.88, N 1.41,
P 6.95. Carbon analyses were consistently low, possibly owing to
incomplete combustion.
(KBr): ν = 3050, 3018, 2918, 2873 (C–H str), 1571 (arom C=C str),
˜
1202 (Pt–Me def), 724 (C–H def) cm–1. FAB-MS: m/z = 762 [M]+.
X-ray quality crystals were grown from benzene/n-pentane.
cis-[PtPh(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (44): This was pre-
pared similarly to 43 by reaction of 2 (80 mg, 0.102 mmol) in di-
ethyl ether with phenyllithium (1.0  in diethyl ether/benzene,
1
103 µL, 0.103 mmol) to give 44 as a white solid (61 mg, 72%). H
NMR (CDCl3): δ = 2.35 (s, 3 H, Me), 2.36 (s, 3 H, Me), 6.8–8.3
(m, 32 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ = –3741 [dd,
J(Pt-P) = 1042, 2067 Hz] ppm. FAB-MS: m/z = 823 [M]+.
cis-[Pt(C6F5)(κ2-C6H3-5-Me-2-PPh2)(PPh2-4-tol)] (45): A solution
of n-butyllithium (1.6  in hexanes, 0.2 mL, 0.32 mmol) was added
to a stirred solution of C6F5Br (79 mg, 0.32 mmol) in diethyl ether
(5 mL) at –78 °C under dry argon. Stirring was continued at –78 °C
for 1 h. To this solution of C6F5Li, the trifluoroacetato complex 6
was added, and the mixture was stirred at –78 °C for 30 min and
at room temperature for 1 h. The turbid solution was treated with
1 drop of methanol, and the solvents were removed in vacuo. The
residue was extracted with toluene, and the solution was chromato-
graphed on a silica gel column. The fraction that eluted with tolu-
ene was concentrated to a small volume under reduced pressure,
and n-pentane was added to precipitate a white solid. This was
isolated by filtration, washed with n-pentane, and dried in vacuo
The same procedure as for complex 19 was used for the following
complexes.
L = PhNH2 (21): Off-white solid (54 mg, 93%) from 1 drop of
1
freshly distilled aniline. H NMR (CDCl3): δ = 2.31 (s, 3 H, Me),
2.32 (s, 3 H, Me), 6.14 [br. s, J(Pt-H) ≈ 40 Hz, 2 H, NH2], 6.7–7.7
(m, 32 H, arom) ppm. 195Pt{1H} NMR (CDCl3): δ = –3855 [dd,
J(Pt-P) = 2018, 3067 Hz] ppm. ES-MS: m/z = 840 [M – BF4]+.
L = o-MeC6H4NH2 (22): Pale red solid (52 mg, 88%) from 1 drop
of freshly distilled o-toluidine. 1H NMR (CDCl3): δ = 2.13 (s, 3 H,
MeC6H4NH2), 2.22 (s, 3 H, tolyl Me), 2.30 (s, 3 H, tolyl Me), 5.93
[br. s, J(Pt-H) ≈ 40 Hz, 2 H, NH2], 6.8–7.6 (m, 31 H, arom) ppm.
195Pt{1H} NMR (CDCl3): δ = –3896 [dd, J(Pt-P) = 2017, 3100 Hz]
ppm. ES-MS: m/z = 854 [M – BF4]+.
1
to give 45 as a monohydrate (136 mg, 83%). H NMR (CDCl3): δ
= 1.54 (br. s, 2 H, H2O), 2.19 (s, 3 H, Me), 2.28 (s, 3 H, Me), 6.6–
7.7 (m, 27 H, arom) ppm. 19F NMR (CDCl3): δ = –116.4 [m, o-F,
J(Pt-F) = 406 Hz], –164.4 [t, p-F, J(Pt-F) = 16.3 Hz], –165.2 (m,
L = m-MeC6H4NH2 (23): Purple solid (54 mg, 92%) from one drop
of freshly distilled m-toluidine. 1H NMR (CDCl3): δ = 2.23 (s, 3
H, Me), 2.24 (s, 3 H, Me), 2.35 (s, 3 H, Me), 6.21 [br. s, J(Pt-H) ≈
m-F) ppm. IR (KBr): ν = 3435 cm–1 (O–H str), 3053, 3022, 2920
˜
Eur. J. Inorg. Chem. 2008, 3467–3481
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3479

M. A. Bennett, S. K. Bhargava, S. H. Privér, A. C. Willis
FULL PAPER
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Received: April 2, 2008
Published Online: June 24, 2008
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