Bis(carbonyl)platinum(II) derivatives: Molecular structure of cis-Pt(CO)2(SO3F)2, complete vibrational analysis of cis-Pt(CO)2Cl2, and attempted synthesis of cis-PT(CO)2F2

Article abstract of DOI:10.1021/ic000280j

As part of a comprehensive study of square planar palladium(II) and platinum(II) carbonyl derivatives, the molecular structure of cis-Pt(CO)₂(SO₃F)₂, the complete vibrational spectra of cis-Pt(CO)₂Cl₂, and the attempted synthesis of cis-Pt(CO)₂F₂ are reported, cis-Pt(CO)₂(SO₃F)₂ is isostructural with cis-Pd(CO)₂(SO₃F)₂ and crystallizes in the monoclinic space, group P2₁/n (no. 14). Crystal data: a = 7.419(1) A; b = 14.751(2) A; c =8.634(1) A; β = 89.95(1)°; V= 944.9(2) A³; Z = 4; T = 300 K; R [F(o) > 4σ(F(o)) = 0.0447 and wR2 = 0.1097. The internal bond parameters of the cis-Pt(CO)₂(SO₃F)₂ are compared to those of cis-Pd(CO)₂(SO₃F)₂, cis-Pt(CO)₂Cl₂, and [M(CO)₄]²⁺, M = Pd, Pt. Solid cis-Pt(CO)₂Cl₂ is studied by IR and Raman spectroscopy, and the data are compared to those of the matrix-isolated complex by IR spectroscopy. Vibrational assignments are supported by DFT calculations, which provide, in addition to vibrational wavenumbers, estimates of IR and Raman band intensities. The positions of 12 of the expected 15 fundamentals of cis-Pt(CO)₂Cl₂ are obtained experimentally. Attempts to synthesize cis-Pt(CO)₂F₂, using, in addition to cis-Pt(Co)₂X₂, X = Cl or SO₃F, [Pt(CO)₄][Sb₂F₁₁]₂ or PtF₆ as starting material and toluene or anhydrous hydrogen fluoride as the reaction medium, are unsuccessful. There are however two interesting results: The reductive carbonylation of PtF₆ in HF produces with [Pt(CO)₄][PtF₆] the first carbonyl fluoride of platinum, and the reaction of [Pt(CO)₄][Sb₂F₁₁]₂ and CsF in HF results in the formation of the previously reported anionic cluster complex Cs₂[Pt₃(CO)₆](n?10). The inclusion of [M(CO)₄]²⁺, M = Pd, Pt, provides new insights into the nature of the Pd(II)-CO and Pt(II)-CO bonds.

Full text of DOI:10.1021/ic000280j

4
424
Inorg. Chem. 2000, 39, 4424-4432
Bis(carbonyl)platinum(II) Derivatives: Molecular Structure of cis-Pt(CO)2(SO3F)2,
Complete Vibrational Analysis of cis-Pt(CO)2Cl2, and Attempted Synthesis of cis-Pt(CO)2F2
†
‡
,†
§
Britta von Ahsen, Rudolf Wartchow, Helge Willner,* Volker Jonas, and
Friedhelm Aubke*,
|
Fachbereich 6, Anorganische Chemie, Gerhard Mercator Universit a¨ t-GH-Duisburg, Lotharstrasse 1,
D-47048 Duisburg, Germany, Institut f u¨ r Anorganische Chemie der Universit a¨ t Hannover,
Callinstrasse 9, D-30167 Hannover, Germany, San Diego Super Computer Centre, MC 0505,
9
500 Gilman Drive, San Diego, California 92093-0505, and Department of Chemistry,
The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T1Z1, Canada
ReceiVed March 13, 2000
As part of a comprehensive study of square planar palladium(II) and platinum(II) carbonyl derivatives, the molecular
structure of cis-Pt(CO)2(SO3F)2, the complete vibrational spectra of cis-Pt(CO)2Cl2, and the attempted synthesis
of cis-Pt(CO)2F2 are reported. cis-Pt(CO)2(SO3F)2 is isostructural with cis-Pd(CO)2(SO3F)2 and crystallizes in the
monoclinic space group P21/n (no. 14). Crystal data: a ) 7.419(1) Å; b ) 14.751(2) Å; c ) 8.634(1) Å; â )
3
8
9.95(1)°; V ) 944.9(2) Å ; Z ) 4; T ) 300 K; R [Fo > 4σ(Fo)] ) 0.0447 and wR2 ) 0.1097. The internal bond
parameters of the cis-Pt(CO)2(SO3F)2 are compared to those of cis-Pd(CO)2(SO3F)2, cis-Pt(CO)2Cl2, and
M(CO)4] , M ) Pd, Pt. Solid cis-Pt(CO)2Cl2 is studied by IR and Raman spectroscopy, and the data are compared
2+
[
to those of the matrix-isolated complex by IR spectroscopy. Vibrational assignments are supported by DFT
calculations, which provide, in addition to vibrational wavenumbers, estimates of IR and Raman band intensities.
The positions of 12 of the expected 15 fundamentals of cis-Pt(CO)2Cl2 are obtained experimentally. Attempts to
synthesize cis-Pt(CO)2F2, using, in addition to cis-Pt(CO)2X2, X ) Cl or SO3F, [Pt(CO)4][Sb2F11]2 or PtF6 as
starting material and toluene or anhydrous hydrogen fluoride as the reaction medium, are unsuccessful. There are
however two interesting results: The reductive carbonylation of PtF6 in HF produces with [Pt(CO)4][PtF6] the
first carbonyl fluoride of platinum, and the reaction of [Pt(CO)4][Sb2F11]2 and CsF in HF results in the formation
2
+
of the previously reported anionic cluster complex Cs2[Pt3(CO)6]n≈10. The inclusion of [M(CO)4] , M ) Pd, Pt,
provides new insights into the nature of the Pd(II)-CO and Pt(II)-CO bonds.
9
Introduction
spectra have in the CO-stretching region νj av(CO) values of
-
1
-1 10
about 2165 cm , slightly above the νj (CO) of 2143 cm
in
The platinum(II) carbonyl chloro complex, cis-Pt(CO)2Cl2,
-
1
gaseous CO and well outside the range of 2125-1850 cm ,
has been known since 1868. Its accidental formation and
4,10-14
subsequent isolation by Sch u¨ tzenberger1,2 predates the discovery
commonly quoted
for terminal CO groups in typical metal
carbonyls. (iii) With only 16 valence electrons associated with
platinum in cis-Pt(CO)2Cl2, the EAN or 18-electron rule is not
observed. This rule is, with very few exceptions, such as
of the first homoleptic transition metal carbonyl, Ni(CO)4, by
3
2
2 years. There are a number of features that set cis-Pt(CO)2Cl2
clearly apart from other transition metal carbonyl complexes:
i) Its square planar coordination geometry, recently confirmed
4
-6
4-6,8
V(CO)6,
generally valid for transition metal carbonyls.
(
7
(iv) The related 18-electron molecules Pt(CO)4 and Pd(CO)4,
which are expected to be isostructural with Ni(CO)4, are claimed
to exist only in inert gas matrixes together with their molecular
by a molecular structure determination, is found neither for
4-7
homoleptic typical transition metal carbonyl complexes, nor
for highly reduced metal carbonylates.8 (ii) Its vibrational
1
5
fragments.
*
To whom correspondence should be addressed. F.A.: phone,
It hence appears that synergetic M-CO bonding according
(
604) 822-3817; fax, (604) 822-2847; e-mail, aubke@chem.ubc.ca.
16-18
to the Dewar-Chatt-Duncanson model,
does not result
H.W.: phone, (49)203-379-3309; fax, (49)203-379-2231; e-mail, willner@
uni-duisburg.de.
in thermodynamically stable carbonyl compounds for zerovalent
†
Gerhard Mercator Universit a¨ t-GH-Duisburg.
Universit a¨ t Hannover.
San Diego Super Computer Center.
The University of British Columbia.
‡
(8) Ellis, J. E. AdV. Organomet. Chem. 1990, 31, 1.
(9) Browning, J.; Goggin, P.; Goodfellow, R. J.; Norton, M. J.; Rattray,
A. J. M.; Taylor, B. F.; Mink, J. J. Chem. Soc., Dalton Trans. 1977,
2061.
(10) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coor-
dination Compounds, 4th ed.; Wiley: New York, 1986.
(11) Braterman, P. S. Metal Carbonyl Spectra; Academic Press: New York,
1975.
§
|
(
(
(
(
1) Sch u¨ tzenberger, P. Bull. Soc. Chim. Fr. 1868, 10, 188.
2) Sch u¨ tzenberger, P. C. R. Hebd. Acad. Sci. 1870, 10, 134.
3) Mond, L.; Langer C.; Quincke, F. J. Chem. Soc. 1890, 57, 749.
4) Cotton, F. A.; Wilkinson, G. AdVanced Inorganic Chemistry, 5th ed.;
Wiley: New York, 1988; pp 58, 1021.
(
(
(
5) Pruchnick, F. P. Organometallic Chemistry of Transition Elements;
(12) Adams, D. M. Metal-Ligand and Related Vibrations; Arnold:
Plenum: New York, 1990.
6) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 2nd ed.; Wiley: New York, 1994.
7) Bagnoli, F.; Belli Dell’Amico, D.; Calderazzo, F.; Englert, U.;
Marchetti, F.; Herberich, G. E.; Pasqualetti, N.; Ramello, S. J. Chem.
Soc, Dalton Trans. 1996, 4317.
London, 1967.
(13) Haines, L. M.; Stiddard, M. H. B. AdV. Inorg. Chem. Radiochem. 1969,
12, 83.
(14) De La Cruz, C.; Sheppard, N. J. Mol. Struct. 1990, 224, 141.
(15) Moskovits, M.; Ozin, G. A. Cryochemistry; Wiley: New York, 1976;
p 261.
1
0.1021/ic000280j CCC: $19.00 © 2000 American Chemical Society
Published on Web 09/01/2000

Bis(carbonyl)platinum(II) Derivatives
Inorganic Chemistry, Vol. 39, No. 20, 2000 4425
Pt and Pd. For cis-Pt(CO)2Cl2 predominantly σ-bonding with
significantly reduced π-back-bonding is in harmony with the
molecular structure of cis-Pd(CO)2(SO3F)2 has been reported
4
0
41,42
in the meantime, and the continued use of superacids
as
known spectroscopic9 and structural properties. The square
,19
7
reaction media in carbonylation reactions has resulted in the
7
planar geometry of cis-Pt(CO)2Cl2, while uncommon in metal-
synthesis of a substantial number of homoleptic metal carbonyl
carbonyl chemistry,4
-6,8
is observed in numerous coordination
cations and their derivatives
25,43
with metals from groups 6-12.
8
complexes of divalent platinum and palladium with a d valence
Most of them have previously been thought to be incapable of
existence.
electron configuration.4
,20
4
-6
44
The difference in M-CO bonding between typical
highly reduced transition metal carbonyl complexes with
significant contributions from π-back-bonding
or
Of particular relevance to this study are the synthesis and
8
45
the molecular structures of salts of the composition [M(CO) ]-
4
16-18,21,22
on one
[Sb F ] , M ) Pd, Pt, with square planar tetracarbonyl cations.
2
11 2
hand and a small group of predominantly σ-bonded halocarbonyl
The synthesis of these species involves the bis(carbonyl)-
complexes of Pt(II), Pd(II), Pd(I), and Au(I)1
9,23-25
on the other
fluorosulfates cis-M(CO) (SO F) , M ) Pd, Pt, as precursors
2
3
2
hand is reflected in different chemical behavior.1
9,23,24
Of
and liquid SbF or the conjugate superacid HF-SbF as the
5
5
4
4,45
relevance to our study are halogen exchange reactions of the
type
reaction medium.
There are three objectives of this study: (i) We will probe
the possible existence of cis-Pt(CO)2F2 by using cis-Pt(CO)2X2,
cis-Pt(CO) Cl + 2HX f cis-Pt(CO) X + 2HCl
33,34
44
46
2
2
2
2
X ) Cl, SO3F,
[Pt(CO)4][Sb2F11]2, and PtF6 as starting
X ) Br, I (1)
materials. As reaction media, both conventional solvents such
4
1,42,47
as toluene and the Brønsted superacid HF
are employed.
For the resulting complexes as well as their trans-iso-
(ii) To complete the structural characterization of the three
1
9,23,24
mers,
the thermal stability of Pt(CO)2X2, X ) Cl, Br, I,
known cis-M(CO) X complexes, with M ) Pd or Pt and X )
2
2
with respect to thermal decomposition to the dimers Pt2X4(CO)2
increases in the order I < Br < Cl.19,26 The inverse order of
thermal stability is generally found for typical metal carbonyl
3 2
Cl or SO F, we report the molecular structure of cis-Pt(CO) -
(SO F) , which permits a comparison of internal bond param-
3
2
7
40
eters to those of cis-Pt(CO) Cl , cis-Pd(CO) (SO F) , and
[M(CO)4] M ) Pd, Pt. (iii) We will present a complete
vibrational characterization in the range of 4000-100 cm of
cis-Pt(CO) Cl by IR spectroscopy of both the solid and the
2
2
2
3
2
4-6
19,23,24,26
2+
halides. The observed order of stability
suggests that
-
1
Pt(CO)2F2 will show even higher thermal stability than the
chloride; however, this compound has not been synthesized so
far, and transition metal carbonyl fluorides of group 10 metals
2
2
complex isolated in an argon matrix complimented by the
27a,b
are rather uncommon.
Raman spectrum of solid cis-Pt(CO)Cl between 3000 and 100
2
-
-1
The formal substitution of Cl by a more electronegative
cm . The vibrational assignments are supported by density
functional calculations, which provide, in addition to band
-
48
ligand, the SO3F anion, is achieved by the reductive carbon-
ylation of Pt(SO3F)428 in the Brønsted superacid HSO3F,
29-32
positions, estimates of the intensities of IR and Raman bands,
33
48
where cis-Pt(CO)2(SO3F)2 forms via the mixed-valency in-
as reported recently. For homoleptic metal carbonyl cations
34
43
termediate [Pt(CO)4][Pt(SO3F)6]. In an analogous manner cis-
and their derivatives, vibrational spectra provide in the CO-
Pd(CO)2(SO3F)2 is obtained33 by the reductive carbonylation
stretching range a more precise estimate of the bond strength
of the CO bond than do molecular structures. An earlier
35
of the mixed-valency compound Pd[Pd(SO3F)6] in HSO3F.
While there is an early, erroneous report, it is generally
36
9
vibrational study is incomplete and reports largely data for
agreed1
9,23-25,37-39
that cis-Pd(CO)2Cl2 is nonexisting. The
benzene solutions of cis-Pt(CO) Cl , which makes a comparison
2
2
to vibrational data for cis-Pt(CO)2Cl2 and cis-M(CO)2(SO3F)2,
M ) Pd, Pt, obtained by us on solid samples, somewhat difficult.
(
(
(
(
(
16) Dewar, J. S. Bull. Soc. Chem. Fr. 1951, 671.
17) Chatt, J.; Duncanson, L. A. J. Chem. Soc. 1953, 2939.
18) Chatt, J.; Wilkins, R. G. J. Chem. Soc. 1952, 2622.
19) Calderazzo, F. J. Organomet. Chem. 1990, 400, 303.
20) Roundhill, M. ComprehensiVe Coordination Chemistry; Pergamon
Press: Oxford, 1987; Vol. 5, p 351.
Experimental Section
(
a) Chemicals. The metal fluorides MF, M ) Na, K, Cs, were
obtained as anhydrous salts from commercial sources and stored inside
a drybox. HgF was synthesized by fluorination of HgCl , and AgF
was formed from Ag CO and 40% aqueous HF. AgF precipitated from
(
21) Pearson, R. G. Inorg. Chem. 1984, 23, 4675.
(22) Parr, R. G.; Donelly, R. A.; Levy, M.; Palke, W. E. J. Chem. Phys.
2
2
1978, 68, 3801.
2
3
(
(
(
(
23) Calderazzo, F. Pure Appl. Chem. 1978, 50, 49.
the saturated AgF solution by adding acetone. The solid AgF was
24) Calderazzo, F.; Belli Dell’Amico, D. Pure Appl. Chem. 1986, 58, 561.
25) Aubke, F.; Wang, C. Coord. Chem. ReV. 1994, 137, 483.
26) Andreini, B. P.; Belli Dell’Amico, D.; Calderazzo, F.; Venturi, M.
G.; Pelizzi, G.; Segre, A. J. Organomet. Chem. 1988, 354, 357.
27) (a) Doherty, N. M.; Hoffman, N. W. Chem. ReV. 1991, 91, 553. (b)
Murphy, E. F.; Murugavel, R.; Roesky, H. W. Chem. Res. 1997, 97,
(39) Stromnova, T. A.; Moiseev, I. I. Russ. Chem. ReV. 1998, 67, 485.
(40) Wang, C.; Willner, H.; Bodenbinder, M.; Batchelor, R. J.; Einstein,
F. W. B.; Aubke, F. Inorg. Chem. 1994, 33, 3521.
(41) Olah, G. A.; Prakash, G. K. S.; Sommer, J. Superacids; Wiley: New
York, 1985.
(
3425.
(
(
(
28) Lee, K. C.; Aubke, F. Inorg. Chem. 1984, 23, 2124.
29) Gillespie, R. J. Acc. Chem. Res. 1968, 1, 202.
30) Thompson, R. C. In Inorganic Sulphur Chemistry; Nickless, G., Ed.;
Elsevier: Amsterdam, 1968; p 587.
(42) O’Donnell, T. A. Superacids and Acidic Melts as Inorganic Reaction
Media; VCH: Weinheim, Germany, 1993.
(43) Willner, H.; Aubke, F. Angew. Chem., Int. Ed. Engl. 1997, 36, 2402.
(44) Hwang, G.; Wang, C.; Aubke, F.; Willner, H.; Bodenbinder, M. Can.
J. Chem. 1993, 71, 1532.
(45) Willmer, H.; Bodenbinder, M.; Br o¨ chler, R.; Hwang, G.; Rettig, S.
J.; Trotter, J.; v. Ahsen, B.; Jonas, V.; Thiel, W.; Aubke, F. J. Am.
Chem. Soc., submitted for publication.
(31) Jache, A. W. AdV. Inorg. Radiochem. 1974, 16, 177.
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(33) Hwang, G.; Wang, C.; Bodenbinder, M.; Willner, H.; Aubke, F. J.
Fluorine Chem. 1994, 66, 159.
(
34) Hwang, G.; Bodenbinder, M.; Willner, H.; Aubke, F. Inorg. Chem.
(46) (a) Weinstock, B.; Classen, H. H.; Malm, J. G. J. Am. Chem. Soc.
1957, 79, 5832. (b) Weinstock, B.; Malm, J. G.; Weaver, E. E. J. Am.
Chem. Soc. 1961, 83, 4310.
(47) Dove, M. F. A.; Clifford, A. F. In Chemistry in Non-Aqueous Ionizing
SolVents; Jander, J., Spandau, H., Addison, C. C., Eds.; Vieweg:
Wiesbaden, 1971; Vols. 1 and 2.
1993, 32, 4667.
(
(
(
35) Lee K. C.; Aubke, F. Can. J. Chem. 1979, 57, 2058.
36) Fink, E. Compt. Rend. 1898, 126, 646.
37) Tripathi, S. C.; Srivastava, S. C.; Mani, R. P.; Shrimal, A. K. Inorg
Chim. Acta 1976, 17, 257.
(
38) Veergaftik, M. N.; Stromnova, T. A.; Moiseev, I. I. Russ. J. Inorg.
(48) Willner, H.; Bach, C.; Wartchow, R.; Wang, C.; Rettig, S. J.; Trotter,
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Chem. 1980, 25, 127.

4426 Inorganic Chemistry, Vol. 39, No. 20, 2000
von Ahsen et al.
40
Table 1. Crystallographic Data for cis-Pt(CO)
cis-Pt(CO) (SO F)
Pt
2
(SO
3
F)
2
in Comparison with cis-Pd(CO)
(SO F)
Pd
2 3 2
(SO F)
2
3
2
cis-Pd(CO)
2
3
2
cis-Pt(CO)
2
(SO
3
F)
2
2 3 2
cis-Pd(CO) (SO F)
empirical formula
fw
C
O F
2 8 2
S
2
C
2
O
8
F
2
S
2
F
calcd (g cm-3)
3.158
30 0. 20 6 × 0.20 × 0.07
2.642
20 2. 10 5 × 0.17 × 0.22
449.23
monoclinic
P2 /n (no.14)
7.419(1)
14.751(2)
8.634(1)
89.95(1)
944.9(2)
4
360.53
monoclinic
P2 /n (no.14)
7.3697(11)
14.7742(35)
8.3237(21)
90.52(2)
906.3(2)
4
cryst dimens (mm)
temp (K)
cryst syst
space group
a (Å)
1
1
λ(Mo KR) (Å)
µ (Mo KR)
min-max 2θ (deg)
R
0.710 73
153.5
5.4-56.4
0.0447a
0.1097
0.710 73
25.2
b (Å)
c (Å)
4-54b
0.027
â (deg)
wR2
R
wF
3
0.034b
V (Å )
Z
a
). b
F
0
> 4σ(F
0
I
0
0
g 2.5σ(I .)
washed with dry acetone and dried in vacuo. Platinum powder (>99%
pure) was donated to us by Degussa-H u¨ ls AG, Germany. cis-Pt(CO) Cl
was obtained by the reductive carbonylation of PtCl , generated in situ
from hexachloroplatinic acid, H PtCl ‚6H O (Chem Pur, Karlsruhe) in
thionyl chloride as described previously.
synthesized by the reductive carbonylation of Pt(SO
platinum powder was first oxidized with S
2
O
6
F
2
in HSO
which was than converted to cis-Pt(CO) (SO F)
F in vacuo, the formation
3
F to give Pt-
28
2
2
(SO
3
F)
4
3
,
2
3
2
as described
3
4
before. During evaporation of excess HSO
3
2
6
2
of small droplets was noted at the reactor wall. The droplets appeared
to contain small crystals. The reactor was closed, without removing
all HSO F. In an atmosphere saturated with gaseous HSO F, small
3 3
crystals formed within a few days, which grew after a further week to
platelike rectangular crystals with an edge length of about 1-3 mm.
The crystals were isolated after removal of all HSO F and cleaved with
3
a metal needle. The fragments were wedged into Lindemann glass
capillaries of 0.2 mm o.d. Since two attempts indicated disorder and
twinning, a small batch of the crystalline sample was recrystallized
from about 2 mL of anhydrous HF. After 2 h of standing at 25 °C, all
HF was removed in vacuo, to yield in addition to crystalline cis-Pt-
2
6,49,50
cis-Pt(CO)
2
(SO
3
F)
in HSO
was prepared by oxidation of platinum with
2
was
2
8
3
F)
4
3
F
3
3
as reported. Pt(SO
in HSO F as solvent. [Pt(CO)
prepared according to published methods. HSO
verkusen) and SbF (Scientific Industrial Association, Moscow) were
3
F)
4
5
1
44
52,53
S
2
O F
6 2
3
4
][Sb
F ]
2 11 2
and PtF
6
were
3
F (Bayer AG, Le-
5
purified by repeated distillation. Toluene was dried over sodium metal
by refluxing. Anhydrous hydrogen fluoride (99% Riedel de Haen) was
handled in a stainless steel vacuum line and stored over small amounts
of SbF
was dried by cooling to -196 °C during vacuum transfer.
b) Instrumentation and Apparatus. (i) General Information. The
equipment and reaction vessels for reactions in anhydrous HF or in
liquid SbF as well as instrumentation and methods to record IR and
Raman spectra have been described very recently.
ii) Matrix Isolation of cis-Pt(CO) Cl . About 50 mg of freshly
sublimed cis-Pt(CO) Cl was introduced inside a drybox (M. Braun,
5
to remove traces of moisture. Carbon monoxide (99%, Linde)
2 3 2
(CO) (SO F) small amounts of a black impurity. Single crystals were
(
selected with a polarizing microscope in a glovebox, and wedged into
capillaries. Data were recorded at room temperature with a Stoe IPDS
diffractometer using graphite-monochromatized Mo KR radiation.
Crystallographic data and details of the structure solution are sum-
5
5
4
4
0
marized in Table 1 and compared to data for cis-Pd(CO)
2 3 2
(SO F) .
(
2
2
The structure of cis-Pt(CO) (SO F) was solved in P2 /n by direct
2
3
2
1
2
2
56
57
methods (SHELXS-86) and refined (SHELXL-93). The programs
MOPLO58 and PLATON were used for the plots and tables.
Uni-Lab 1200/18) into a small U-shaped trap, which was then
59
incorporated into the matrix isolation apparatus55 in front of the matrix
support (metal mirror). With the sample held at 21 °C and a flow rate
-
1
Results and Discussion
of argon of about 3 mmol h passed over the sample, a sufficient
amount of cis-Pt(CO) Cl could be sublimed and gave a satisfactory
argon matrix at 12 K on the matrix support. To record an IR spectrum
2
2
(a) Synthetic Aspects. For the synthesis of cis-Pt(CO)2Cl2
and cis-Pt(CO)2(SO3F)2 a common general method is used, the
reductive carbonylation of platinum(IV) chloride or fluorosulfate
in nonaqueous solvents according to the general equation
-
1
in the range from 5000 to 400 cm , a matrix was prepared with 2
-
1
mmol of argon with an extinction maximum of 1.4 at 2171.1 cm . A
second matrix was prepared from 4 mmol of argon for recording the
-
1
spectral region from 650 to 100 cm with an extinction maximum of
4
0-80 °C, 1 atm
-
1
0
.44 at 468.3 cm . Matrix IR spectra were recorded with a Bruker
PtX + 3CO
8 cis-Pt(CO) X + COX
2 2 2
SOCl2 or HSO3F
4
IFS 66v FT spectrometer operating in the reflectance mode with the
help of a transfer optic. A DTGS detector together with a KBr/Ge beam
X ) Cl, SO F (2)
3
-
1
splitter operated in the region of 5000-400 cm . Far-IR spectra in
-
1
the range of 650-100 cm were recorded with a DTGS detector
There are however considerable differences between both
synthetic approaches. For the synthesis of cis-Pt(CO)2Cl2, there
together with a Ge coated Mylar beam splitter. Thirty-two scans were
co-added for each spectrum, using an apodized resolution of 1.0 cm-1
.
26,49,50
are in addition to the reductive carbonylation of PtCl4
thionyl chloride a number of alternative routes available
including the original method of Sch u¨ tzenberger. The method
chosen here, originally reported by Calderazzo et al.,2 is very
convenient and involves only commercially available reagents
or solvents. Thionyl chloride is used both as a reagent in the
in
(
iii) Crystal Growth and X-ray Diffraction of cis-Pt(CO)
2 3 2
(SO F) .
7,19,26
To produce a sufficiently large sample for all measurements, 1 g of
1,2
6,49
(
(
(
49) Belli Dell’Amico, D.; Calderazzo, F.; Dell’Amico, G. Gazz. Chim.
Ital. 1977, 107, 101.
50) Belli Dell’Amico, D.; Calderazzo, F.; Veracini, C. A.; Zandona, N.
Inorg. Chem. 1984, 23, 3030.
51) (a) Cady, G. H.; Shreeve, J. M. Inorg. Synth. 1963, 7, 124. (b) Zhang,
D.; Wang, C.; Mistry, F.; Powell, B.; Aubke, F. J. Fluorine Chem.
26,49
synthesis of anhydrous PtCl4 from H2PtCl6‚6H2O
and as the
reaction medium in the subsequent reductive carbonylation of
2
6,49,50
PtCl4.
1
996, 76, 83.
52) (a) Weinstock, B.; Classen, M. H.; Malm, J. G. J. Am. Chem. Soc.
957, 79, 5832. (b) Weinstock, B.; Malm, J. G.; Weaver, E. E. J. Am.
(
1
(56) Sheldrick, G. M. SHELXS-86. Program for crystal structure deter-
mination, University of G o¨ ttingen, 1986.
Chem. Soc. 1961, 83, 4310.
(53) Ahsen, B. v.; Bach, C.; Pernice, H.; Willner, H.; Aubke, F. J. Fluorine
Chem. 2000, 102, 243.
(57) Sheldrick, G. M. SHELXL-93. Program for crystal structure refine-
ment, University of G o¨ ttingen, 1993.
(
54) Bernhardt, E.; Bley, B.; Wartchow, R.; Willner, H.; Bill, E.; Kuhn,
P.; Sham, I. H. T.; Bodenbinder, M.; Br o¨ chler, R.; Aubke, F. J. Am.
Chem. Soc. 1999, 121, 7188.
(58) Spek, A. L. PLATON, an integrated tool for the analysis of the results
of a single crystal structure determination. Acta Crystallogr. 1990,
A46 (Suppl.), C-34.
(
55) Arguello, G. A.; Grothe, H.; Kronberg, M.; Willner, H.; Mack, H.-G.
(59) Thiele, G. MOPLO, ein elektronischer Molek u¨ lbaukasten auf dem PC,
VCH software, Verlag Chemie.
J. Phys. Chem. 1995, 99, 17525.

Bis(carbonyl)platinum(II) Derivatives
Inorganic Chemistry, Vol. 39, No. 20, 2000 4427
8
0 °C
Conclusions regarding the formation of cis-Pt(CO)2Cl2 by the
2+
-
[
Pt(CO)4]
+ 2SO3F
(solv)
HSO3F8
5
0
(solv)
reductive carbonylation in SOCl2 have been reported. When
the dimer Pt2(CO)2(µ-Cl)2Cl2 is employed as starting material,
the reaction produces at -80 °C only trans-Pt(CO)2Cl2:
cis-Pt(CO) (SO F) + 2CO(g) (5)
2
3
2(s)
These findings are supported by Raman and IR spectra in
-
80 °C
1
3
HSO3F solution, C NMR studies, and the solution behavior
Pt (CO) (µ-Cl) Cl + 2CO {
} 2 trans-Pt(CO) Cl (3)
2
2
2
2
2 2
4
4
of [Pt(CO)4][Sb2F11]2 in fluorosulfuric acid. The exclusive
formation of the cis-isomer during the substitution reaction
reflects the greater trans-directing ability of CO in substitution
At room temperature, trans-Pt(CO)2Cl2 will convert spontane-
ously to the cis-isomer, which appears to be thermodynamically
the more stable isomer of the two.50 In the case of cis-Pt(CO)2-
SO3F)2, there is no evidence for a trans-isomer and the
corresponding µ-SO3F dimer is so far unknown as well.
6
3
reactions of square planar complexes. A very similar course
6
4
of the reductive carbonylation of Au(SO3F)3 in HSO3F is
(
+
reported where linear [Au(CO)2] (solv) is initially formed and
6
5,66
then converted into Au(CO)SO3F.
3
3
As eq 2 suggests, the synthesis of cis-Pt(CO)2(SO3F)2 by
reductive carbonylation of Pt(SO3F)428 in fluorosulfuric acid
appears to proceed in a manner similar to that of cis-Pt(CO)2Cl2.
HSO3F is used both in the synthesis of Pt(SO3F)4 from Pt
powder and bis(fluorosulfuryl)peroxide, S2O6F2,51 and as the
reaction medium for the subsequent reductive carbonylation,
which no longer involves only commercially available reagents.
Also the byproduct of the reduction, CO(SO3F)2, is thermally
unstable at room temperature60 and will decompose quantita-
tively to CO2 and S2O5F2. Both are separated easily from the
main product because of their volatilities. There are to our
knowledge no alternative routes to cis-Pt(CO)2(SO3F)2, and our
attempts at a conversion of cis-Pt(CO)2Cl2 into the fluorosulfate
by dissolution in HSO3F are unsuccessful and result in the
formation of a brown-colored oily mass, with very little
evolution of HCl.
The synthesis of cis-Pd(CO)2(SO3F)2 is best accomplished
29-31
by the reductive carbonylation of the mixed-valency compound
6
7
Pd[Pd(SO3F)6] in a solid-gas reaction according to
2
5 °C, 550 Torr of CO
Pd[Pd(SO
F)
]
(s) + 5CO(g)
8
3
6
1
h
2
cis-Pd(CO) (SO F) + CO2(g) + S O F
(6)
2
3
2(s)
2
5
2(1)
while in HSO3F the reaction appears to be rather complex.33,40
The carbonylation of cis-M(CO)2(SO3F)2, M ) Pd, Pt, in
liquid SbF5 to give cleanly and quantitatively [M(CO)4][Sb2F11]2,
4
4
M ) Pd, Pt, is reported. We have now found that cis-Pt-
CO)2Cl2 can also be converted into [Pt(CO)4][Sb2F11]2 by
carbonylation in SbF5; however, the reaction is rather slow, and
(
4
3
the byproduct, formulated as SbF4Cl, is more difficult to
remove from the product mixture than is the rather volatile
A more substantial difference in the formation reactions (eq
67
Sb2F9(SO3F) in the originally reported synthesis of [M(CO)4]-
2
) of cis-Pt(CO)2Cl2 and cis-Pt(CO)2(SO3F)2 is due to the
[
Sb2F11], M ) Pd, Pt.44 Hence, the conversion of cis-Pt(CO)2Cl2
6
1
reaction medium used, the aprotic solvent SOCl2, and the
into [Pt(CO)4][Sb2F11]2 is not a useful synthetic route.
29-32
strongly ionizing Brønsted superacid HSO3F.
In HSO3F
the starting material Pt(SO3F)4 will dissolve28 to give rise to a
A rather elegant synthesis of [Pt(CO)4][Sb2F11]2, the reductive
5
2
4
1,42
carbonylation of PtF6 in SbF5, has been reported by us very
diprotonic conjugate Brønsted-Lewis superacid,
with
53
Pt(SO3F)6]2 as a self-ionization ion. Consequently, in the
-
28
recently. In anhydrous HF the reductive carbonylation of PtF6
produces quantitatively [Pt(CO)4][PtF6], the first example of a
platinum carbonyl fluoride of the net composition Pt(CO)2F3.53
However, all attempts to convert this compound into cis-Pt-
[
initial stages of the reductive carbonylation, an intermediate,
formulated as the mixed-valency complex [Pt(CO)4][Pt(SO3F)6],
3
4
is isolated and characterized by vibrational spectroscopy. In
the meantime both constituent ions are structurally characterized
by us as [Pt(CO)4][Sb2F11]245 and Cs2[Pt(SO3F)6], respectively.
As the reductive carbonylation of Pt(SO3F)4 in HSO3F progresses,
the intermediate [Pt(CO)4][Pt(SO3F)6] redissolves and is quan-
titatively converted into cis-Pt(CO)2(SO3F)2.33 This suggests that
the initial product of the reduction is the solvated cation [Pt-
(
CO)2F2 under more forcing conditions (higher temperatures and
CO pressures) in analogy to the conversion of [Pt(CO)4][Pt-
62
33,34
(
SO3F)6] into cis-Pt(CO)2(SO3F)2
are unsuccessful. Equally
unsuccessful are a number of additional attempts at the synthesis
of cis-Pt(CO)2F2: The solvolysis of cis-Pt(CO)2Cl2 in HF does
not take place, and the reagent is recovered unchanged. This
1
9,26
approach with HX, X ) Br, I, leads reportedly
to cis-Pt-
2
+
(
CO)4] (solv):
(
CO)2X2, X ) Br, I (see eq 1); however the high enthalpy of
6
8a
formation for HF makes solvolysis in anhydrous HF ther-
modynamically unfeasible. As discussed in the Experimental
Section, cis-Pt(CO)2(SO3F)2 can be recrystallized from anhy-
drous HF. Addition of NaF to the solution results in a complete
loss of CO and a rather complex product mixture. Attempted
methatetical reactions of cis-Pt(CO)2Cl2 with AgF or HgF2 in
toluene or HF give rise to redox reactions and the formation of
4
0-80 °C, 1 atm of CO
Pt(SO F)
+ 5CO(g)
4(solv)
8
3
HSO3F
2
+
-
[
Pt(CO)4]
+ CO2(g) + S O F
+ 2SO3F
(4)
(solv)
(solv)
2
5
2(1)
2
-
In the initial phase of the reaction with unreacted [Pt(SO3F)6]
34
still present, [Pt(CO)4][Pt(SO3F)6] forms as intermediate. With
increasing SO3F concentration, after all the Pt(IV) species has
been reduced and converted to [Pt(CO)4] , nucleophilic
-
2
+
(63) Wilkins, R. G. Kinetics and Mechanism. of Reactions of Transition
metal Complexes, 2nd ed.; VCH: Weinheim, 1991.
64) (a) Lee, K. C.; Aubke, F. Inorg. Chem. 1979, 18, 389. (b) Lee, K. C.;
-
substitution by SO3F occurs according to
(
Aubke, F. Inorg. Chem. 1980, 19, 119.
(65) Willner, H.; Aubke, F. Inorg. Chem. 1990, 29, 2195.
(
(
(
60) (a) Belli Dell’Amico, D.; Calderazzo, F.; Veracini, C. A.; Zandona,
N. Inorg. Chem. 1984, 23, 3030. (b) Lustig, M. Inorg. Chem. 1965,
(66) Willner, H.; Schaebs, J.; Hwang, G.; Mistry, F.; Jones, R.; Trotter, J.;
Aubke, F. J. Am. Chem. Soc. 1992, 114, 8972.
(67) Wilson, W. W.; Aubke, F. J. Fluorine Chem. 1979, 13, 431.
(68) (a) Johnson, D. A. Some Thermodynamic Aspects of Inorganic
Chemistry; Cambridge University Press: Cambridge, U.K., 1968. (b)
Clark, H. C. S.; Fawcett, J.; Holloway, J. A.; Hope, E. G.; Peck, L.
A.; Russell, D. R. J. Chem. Soc., Dalton Trans. 1998, 1249.
4, 1828.
61) Paul, R. C.; Singh, G. In The Chemistry of non-Aqueous SolVents;
Lagowskii, J. J., Ed.; Academic Press: New York, 1978; Vol. V B,
p 251.
62) Zhang, D.; Rettig, S. J.; Trotter, J.; Aubke, F. Inorg. Chem. 1996, 35,
6113.

4428 Inorganic Chemistry, Vol. 39, No. 20, 2000
von Ahsen et al.
Ag or Hg, respectively. The nucleophilic substitution of [Pt-
Ru, Os,72 where for the 5d complex very slightly smaller unit
cell volumes (between 0.3% and 0.9%) are observed than for
2
+
(CO)4]
in HF does not occur: [Pt(CO)4][PtF6] remains
unchanged, and [Pt(CO)4][Sb2F11]2 can be recrystallized from
HF.
the corresponding 4d complex. It has been concluded that in
4
5
73,74
addition to relativistic effects
contacts between the C atoms of the dipositive cations and F
stronger interionic secondary
7
5
The lack of success in obtaining cis-Pt(CO)F2 should not be
surprising. As relevant reviews in ref 27a,b indicate, fluoro
complexes of Pt(II) with better stabilizing ligands (phosphines
or chelating phosphines) are thermally unstable. A case in point
45
atoms of the fluoroantimonate anions are found for the Pt(II),
48
72
Ir(III), and Os(II) salts than are observed for the correspond-
ing Pd(II), Rh(III),48 and Ru(II) complexes in the four
isostructural pairs, and that these stronger interionic contacts
are largely responsible for the observed contractions in unit cell
volumes of the 5d metal complexes.
4
5
72
is a recent study by E. G. Hope et al.6 on [(PR3)3PtF] and
8b
+
related complexes.
A rather unexpected product is observed when [Pt(CO)4]-
[
Sb2F11]2 is reacted with a solution of CsF in anhydrous HF.
In the neutral molecules cis-Pt(CO)2(SO3F)2 and cis-Pd(CO)2-
SO3F)2, weaker inter- and intramolecular secondary contacts
about four per CO group) are observed. These contacts involve
The evolution of gas is noted, and a black solid is formed. The
gas phase contains a mixture of CO and COF2. The IR spectrum
shows in addition to bands due to Cs[SbF6]69 strong absorptions
in the CO-stretching region at 2074, 1885, and 1830 cm . The
intense color and the observed band positions suggest the
presence of an anionic platinum carbonyl cluster species of
the type [Pt3(CO)6]n2 with n ≈ 10. These cluster anions are
obtained by the reductive carbonylation of Na2[PtCl6]‚6H2O in
aqueous alkaline solution or of cis-Pt(CO)2Cl2 in THF or
methanol.70 According to the molecular structures, trinuclear
40
(
(
terminal oxygen atoms of the fluorosulfate ligands and the
carbon atoms of the CO ligands. Because the strengths of
intermolecular contacts in cis-Pt(CO)2(SO3F)2 are comparable
with those in cis-Pd(CO)2(SO3F)2, the higher cell volume of
the platinum compound is understandable. Judging by the sums
-1
7
0
-
76
of the van der Waals radii, there are no significant secondary
contacts involving the metal atoms in the two isostructural pairs
71
40
45
cis-M(CO)2(SO3F)2 and [M(CO)4][Sb2F11]2, M ) Pd, Pt.
[Pt3(CO)3(µ-CO)3] moieties of point group D3h are stacked into
This is surprising, since with square planar coordination
geometries for the metals in both pairs, the central atom should
be equally well accessible. It hence appears that a higher partial
positive charge resides on the C atoms of the predominantly
2-
columns of the type [Pt3(CO)3(µ-CO)3]n with n ) 1-6 ∼10.
The formation of anionic clusters of this type in basic HF
solution is rather unusual, and no clear explanation for the
formation reaction can be offered at this time.
As discussed earlier for cis-Pd(CO)2(SO3F)2,40 the growth of
single crystals is difficult and tedious as well for cis-Pt(CO)2-
77
σ-bonded and strongly polarized CO ligands.
As discussed in some detail for cis-Pd(CO)2(SO3F)240 and
illustrated by the packing of four molecules in the unit cell, as
a consequence of the significant intermolecular OC- - -OS
contacts, the molecular structure is expanded into a 3-dimen-
(
SO3F)2 because of the high solubility of both salts in fluoro-
sulfuric acid (see the Experimental Section). To obtain single
crystals, suitable for a molecular structure determination,
recrystallization from anhydrous HF is needed. The molecular
structure of cis-Pt(CO)2(SO3F)2 will be discussed in the next
section.
40
sional, supramolecular network. A similar packing arrangement
is found for the cis-Pt(CO)2(SO3F)2 molecule, but this will not
be discussed here, to avoid repetition.
A slightly different packing arrangement is reported for cis-
In summary, even though cis-Pt(CO)2(SO3F)2 has been known
7
Pt(CO)2Cl2, which crystallizes in the same monoclinic space
3
3
since 1994, the exact pathway of its formation in HSO3F has
only recently become known and is reported here. Interestingly,
cis-M(CO)2(SO3F)2, M ) Pd, Pt, is both a convenient starting
material for the synthesis of [M(CO)4][Sb2F11]2 in liquid SbF5
and a reaction product of the nucleophilic substitution of
group as cis-M(CO)2(SO3F)2, M ) Pd, Pt. Here the essentially
square planar molecules are stacked along the c-axis parallel to
each other but are rotated in such a manner as to allow secondary
C- - -Cl contacts between adjacent molecules. As a consequence
of the stacking, rather short Pt- - -Pt contacts of 3.378(1) Å7
form. A similar packing arrangement due to C- - -Cl contacts
M(CO)4]2 by SO3F in HSO3F. The related platinum(II)
+
-
[
carbonyl fluoride, cis-Pt(CO)2F2, remains unknown, and di-
7
8
is present in linear Au(CO)Cl in the solid state. It appears the
more complicated, 3-dimensional packing arrangement observed
5
3
nuclear [Pt(CO)4][PtF6], reported by us very recently, is so
far the only stable, isolated metal carbonyl fluoride formed by
a group 10 element. The material is characterized by vibrational
4
0
for cis-M(CO)2(SO3F)2, M ) Pd, Pt, is a consequence of the
molecular nature of the -OSO2F ligand, where more significant
5
3
methods.
b) Structural Aspects. Crystallographic data for cis-Pt(CO)2-
SO3F)2 are listed in Table 1 and are compared to the previously
40
and varied secondary intermolecular contacts are possible than
(
is the case for the chloro ligand in cis-Pt(CO)2Cl2.7
(
40
The noted similarity in the packing of molecules within the
unit cells (see Figure 2 in ref 40) for cis-Pt(CO)2(SO3F)2 and
cis-Pd(CO)2(SO3F)2 extends also to the molecular structure
which is shown for cis-Pt(CO)2(SO3F)2 in Figure 1. Selected
interatomic distances, bond angles for the immediate coordina-
tion environment of M(II), and torsion angles for both molecules
are listed in Table 2. The two fluorosulfate groups both fall
below the molecular plane formed by the M(CO)2O2 moiety,
M ) Pd, Pt. A similar pairwise arrangement of fluorosulfate
reported data for cis-Pd(CO)2(SO3F)2.
As can be seen, both compounds are isostructural and the
lattice parameters are very similar. The unit cell volume of cis-
Pt(CO)2(SO3F)2 is about 4.1% larger than that of the palladium
compound. This is due in part to the data collection for the Pt
compound at higher temperature, but this larger volume is in
contrast to observations for the isostructural pairs [M(CO)4]-
45
48
[
[
Sb2F11]2, M ) Pd, Pt, [M(CO)5Cl][Sb2F11]2, M ) Rh, Ir,
M(CO)6][Sb2F11]2, M ) Ru, Os,7 and [M(CO)6][SbF6]2, M )
2
(
69) Weidlein, J.; M u¨ ller, U.; Dehnicke, K. Schwingungsfrequenzen; Thieme
(73) Pyykk o¨ , P.; Desclaux, J. P. Acc. Chem. Res. 1979, 12, 276.
(74) Pyykk o¨ , P. Chem. ReV. 1988, 88, 563.
(75) Alcock, N. W. AdV. Inorg. Chem. Radiochem. 1972, 15, 1.
(76) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(77) Goldman, A. S.; Krogh-Jespersen, K. J. Am. Chem. Soc. 1996, 118,
12159.
Verlag: Stuttgart, 1981.
(
(
70) Longoni, G.; Chini, P. J. Am. Chem. Soc. 1976, 98, 7225.
71) Calabrese, J. C.; Dahl, L. F.; Chini, P.; Longoni, G.; Martinengo, S.
J. Am. Chem. Soc. 1974, 96, 2614.
(72) Bernhardt, E.; Bach, C.; Wartchow, R.; Willner, H.; Aubke, F. Inorg.
Chem., to be submitted for publication.
(78) Jones, P. G. Z. Naturforsch. 1982, 37 B, 823.

Bis(carbonyl)platinum(II) Derivatives
Inorganic Chemistry, Vol. 39, No. 20, 2000 4429
Table 2. Selected Internal Bond Parameters for cis-M(CO)
2 3
(SO F)
2
, M ) Pd, Pt
40
40
cis-Pt(CO)
2
(SO
3
F)
2
cis-Pd(CO)
2 3
(SO F)
2
cis-Pt(CO)
2 3
(SO F)
2
2 3 2
cis-Pd(CO) (SO F)
(
a) Bond Lengths (Å)
M-C(1)
1.868(13)
1.897(13)
2.024(9)
1.919(5)
1.945(5)
2.016(3)
2.006(3)
1.479(3)
1.422(4)
1.413(4)
S(1)-F(1)
S(2)-O(21)
S(2)-O(22)
S(2)-O(23)
S(2)-F(2)
C(1)-O(1)
C(2)-O(2)
1.535(8)
1.474(8)
1.426(11)
1.346(18)
1.565(15)
1.130(17)
1.103(16)
1.557(3)
1.480(3)
1.402(4)
1.394(4)
1.565(4)
1.114(6)
1.102(6)
M-C(2)
M-O(11)
M-O(21)
S(1)-O(11)
S(1)-O(12)
S(1)-O(13)
2.022(9)
1.482(12)
1.399(10)
1.401(10)
(
b) Bond Angles (deg)
O(11)-M-O(21)
O(11)-M-C(2)
O(11)-M-C(1)
O(21)-M-C(2)
O(21)-M-C(1)
84.5(4)
92.7(5)
175.3(5)
176.1(5)
91.1(5)
86.0(1)
91.7(2)
176.2(2)
176.3(2)
90.4(2)
C(2)-M-C(1)
M-C(2)-O(2)
M-C(1)-O(1)
M-O(11)-S(1)
M-O(21)-S(2)
91.5(5)
91.8(2)
178.3(11)
176.6(12)
125.1(6)
124.7(6)
178.9(4)
177.5(4)
123.5(2)
124.7(2)
(
c) Torsion Angles (deg)
O(21)-M-O(11)-S(1)
O(11)-M-O(21)-S(2)
-122.8(7)
105.3(7)
-122.0(2)
106.5(2)
F(1)-S(1)-O(11)-M
F(2)-S(2)-O(21)-M
72.3(7)
81.1(8)
73.8(2)
83.0(2)
Table 3. Selected Structural and Vibrational Data for Cationic Palladium(II) and Platinum(II) Carbonyl Complexes
νj av(CO) (cm-1)
f
CO × 10 (N m-1
2 d
)
refa
compound
Pd(CO) ][Sb
Pt(CO) ][Sb
(SO
d
av(M-C) (Å)
d
av(C-O) (Å)
[
[
4
2
F
11
]
2
1.992(2)
1.982(9)
1.932(5)
1.882(3)
1.897(5)
1.88(3)
1.106(6)
1.110(9)
1.108(6)
1.116(6)
1.115(6)
1.06(4)
2259
2261
20.63
20.64
19.87
19.56
18.67
17.93
45, 44
45, 44
40, 33
b, 34
7, b
26, 26
4
2
F
11
]
2
cis-Pd(CO)
2
3
F)
F)
2
2217.5
2202e
2171
cis-Pt(CO)
cis-Pt(CO)
2
(SO
3
2
2
Cl
2
2
trans-Pt (CO)
2
I
2
(µ-I)
2
2106c
a
The first reference listed refers to structural data; the second reference refers to vibrational data. b This work. c Solution in n-heptane.
d
Approximation according to Cotton, F. A.; Kraihanzel, C. S. J. Am. Chem. Soc. 1962, 84, 4432. e IR data of solid cis-Pt(CO)
2 2
Cl at room temperature
(see Table 4).
bonds. The variation in bond lengths is attributed to the
participation of O(S) and C(O) atoms in intermolecular and
intramolecular, secondary interactions of variable strength.40
Likewise the observed slight deviation from linearity for the
M-C-O groups with bond angles between 176.6(12)° and178.9-
(
4)° is attributed to the involvement of carbon in inter- and
intramolecular contacts. These deviations from linearity for the
M-C-O groups are observed for all other structurally char-
4
5,48,59,72,80-82
acterized metal carbonyl cations,
with fluoroanti-
monate(V) anions, where in all instances significant interionic
C- - -F contacts are found.
When interatomic distances for cis-Pt(CO)2(SO3F)2 and its
palladium(II) analogue are compared, it is noted that the Pt-C
distances are significantly shorter than the corresponding Pd-C
bond lengths, while M-O and C-O distances show small
differences, usually within error limits.
2 3 2
Figure 1. Molecular structures of cis-M(CO) (SO F) , M ) Pd, Pt,
with 50% probability thermal ellipsoids shown. Bond distances for cis-
Pt(CO) (SO F) are in bold.
2
3
2
ligands is found in the square planar structures of [Au(SO3F)4]- 62
To allow a broader comparison, we have summarized in Table
average M-C and C-O distances for all six structurally
3
and for the terminal fluorosulfate groups in dimeric [Au-
7
9
characterized cationic or neutral Pt(II) and Pd(II) derivatives,
including so far unpublished structural data for [M(CO)4]-
(SO3F)3]2.
Both M(CO)2(SO3F)2, M ) Pd, Pt, molecules have no
crystallographic symmetry. This is in particular apparent from
4
5
[
Sb2F11]2, M ) Pd, Pt. As can be seen in Table 3 there are
generally significant differences in metal-carbon distances,
while d(C-O) values vary little. It is commonly observed that,
the two torsion angles F(1)-S(1)-O(11)-M and F(2)-S(2)-
O(21)-M, M ) Pd,40 Pt, listed in Table 2, which have
1
9,25,43
for cationic carbonyl compounds,
the C-O distances are
comparable but different magnitudes in both molecules (see
Table 2). Mirror symmetry would require an opposite sense of
rotation for both sets of angles. This is again similar to findings
at the shorter end of bond lengths listed in the Cambridge data
index with a mean distance of 1.143 Å and a lower quartile
8
3
-
62
79
value of 1.132 Å based on 10 022 examples. However, C-O
for [Au(SO3F)4]
instances
and [Au(SO3F)3]2. There is also in all
4
0,62,79
a small displacement of the metal out of the
(
80) Bodenbinder, M.; Balzer-J o¨ llenbeck, G.; Willner, H.; Batchelor, R.
principal molecular plane.
J.; Einstein, F. W. B.; Wang, C.; Aubke, F. Inorg. Chem. 1996, 35,
The distances of chemically equivalent bonds are generally
not significantly different in both M(CO)2(SO3F)2, M ) Pd,
Pt, molecules with the exception of terminal S-O and M-C
82.
4
0
(81) Br o¨ chler, R.; Freidank, D.; Bodenbinder, M.; Sham, I. H. T.; Willner,
H.; Rettig, S. J.; Trotter, J.; Aubke, F. Inorg. Chem. 1999, 38, 3684.
82) Br o¨ chler, R.; Sham, I. H. T.; Bodenbinder, M.; Schmitz, V.; Rettig,
(
S. J.; Trotter, J.; Aubke, F. Inorg. Chem. 2000, 39, 2172.
(83) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
(79) Willner, H.; Rettig, S. J.; Trotter, J.; Aubke, F. Can. J. Chem. 1991,
69, 391.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, Suppl., 1.

4430 Inorganic Chemistry, Vol. 39, No. 20, 2000
von Ahsen et al.
bond distances are apparently insensitive to small changes in
the high CO bond order in metal carbonyl cations and their
derivatives.4 Therefore, average CO-stretching wavenumbers
νj av(CO) and CO-stretching force constants, fCO, are included in
Table 3. They provide a more accurate and sensitive estimation
of the strength of the CO bond.
(CO)2(SO3F)2 (1.882(3) Å) and well above the qu value of 1.878
8
3
Å in the Cambridge data compilation. These facts are
contradictory; while the vibrational criteria ( νj av(CO) and fCO)
suggest increased π-back-bonding for cis-Pt(CO)2Cl2 relative
to cis-Pt(CO)2(SO3F)2, the opposite conclusion may be drawn
from the structural features d(Pt-CO) in both compounds. The
correspondence between long M-C bonds and high CO values
in Table 3 commonly observed for homoleptic metal carbonyl
3,44
As can be seen in Table 3, structural and vibrational data for
4
4,45
the isostructural pair [M(CO)4][Sb2F11]2, M ) Pd, Pt,
are
4
3
89,90
essentially identical within esd values. Due to relativistic
cations, in accordance with theoretical studies,
does not
7
3,74
effects,
the effective radii of Pt(II) and Pd(II) appear to be
apply to the cis-Pt(CO)2Cl2-cis-Pt(CO)2(SO3F)2 pair.
the same in both cations. The metal-carbon distances are the
longest so far observed in metal carbonyls of Pd(II) and Pt(II)
and for the latter well in excess of qu, the upper quartile values
A similar situation has been found recently for the trans-
(O-C)-Ir(III)-X, X ) Cl, SO3F, segments in the molecular
48,84
91
structures of [Ir(CO)5Cl][Sb2F11]2
and mer-Ir(CO)3(SO3F)3,
8
3
-
-
of 29 data sets in the Cambridge data compilation. The
where Cl appears to weaken while SO3F strengthens the Ir-
-
1
observed νav(CO) and fCO values of about 2260 cm and 20.6
(III)-CO bonds trans to the anionic ligands relative to the
2
-
×
10 N m are the highest for square planar metal carbonyl
remaining Ir(CO)n, n ) 4, 2, bonds in the molecules cis to Cl
44
-
derivatives. They are surpassed only by data for linear [Hg-
CO)2]
octahedral [Ir(CO)6]
The three sets of data from [Sb2F11] salts in all instances
or SO3F . Due to vibrational mixing of the CO-stretching
2
+ 80
-1
2
-1
48,84,91
(
(2280 cm and 21.0 × 10 N m ) or tripositive,
vibrations in both molecules,
νav(CO) and fCO for the trans-
3
+ 53,84
-1
2
-1
(2268 cm and 20.8 × 10 N m ).
CO groups are not obtainable. For the approximately linear
-
-1 9
molecules Au(CO)Cl ( νj (CO) ) 2183 cm ) and Au(CO)SO3F
-
1 65
represent the closest approach for “σ-only” M-CO bonding for
( νj (CO) ) 2198 cm ), only the molecular structure of Au-
8
0
44,45
53,84
78
linear, square planar,
and octahedral
geometries.
(CO)Cl is known, which precludes a comparison.
From the examples cited above, it appears the Cl and SO3F
2
+
-
-
The substitution of two trans-CO ligands of the [M(CO)4]
-
-
cations, M ) Pd, Pt, by anions (SO3F or Cl ) to produce the
neutral molecules cis-Pt(CO)2Cl2 and cis-M(CO)2(SO3F)2,
M ) Pd, Pt, is expected to reduce the Lewis acidity of the metal
center. As can be seen from the data in Table 3, the M-CO
bonds to the remaining carbonyl ligands, trans to the anionic
ligands, shorten, while νj av(CO) and fCO decrease, suggestive of
a reduction in C-O bond strength. For the two fluorosulfate
derivatives, the decrease in dav(M-C), νj av(CO), and fCO is larger
for cis-Pt(CO)2(SO3F)2 than for its Pd analogue, with νav(CO)
affect the trans-CO ligand differently. The more electronegative
-
SO3F group reduces the Lewis acidity of the metal center to
a lesser degree than the chloro ligands, which is reflected in
higher νj (CO) values for the fluorosulfates. On the other hand,
the -OSO2F ligand appears to increase π-contributions to the
48,84
-
M-C, M ) Pt, Ir,
bond more effectively than the Cl ligand,
which results in shorter M-C bonds for the former.
(c) Vibrational Analysis of cis-Pt(CO)2Cl2. For the square
planar, seven-atom molecule of point group C2V, the irreducible
representations of the fundamental vibrations are
-
1
1
5 cm higher in cis-Pd(CO)2(SO3F)2. This is not uncommon,
because in palladium(II) and platinum(II) halo carbonyls of
comparable composition and identical structures, νj av(CO) is
Γvib ) 6A (IR, Ra p) + 2A (Ra dp) +
1
2
usually about 30 cm- higher in the palladium compound.
1
19,26,85-87
2
B (IR, Ra dp) + 5B (IR, Ra dp)
1
2
In two structurally characterized [n-Bu4N][MCl3(CO)] salts with
M ) Pd85 or Pt, d(Pd-C) and d(Pt-C) are 1.87(1) and 1.82-
88
Hence, there are 15 Raman-active and 13 IR-active funda-
mentals expected. A complete vibrational analysis of cis-Pt-
(
1) Å, respectively, while the νj (CO) values are 2132 and 2098
-
1
cm . It appears that Pt(II) is both a better π-acceptor toward
the anionic ligand and a better π-donor toward CO than is Pd-
(
CO)2Cl2 is of interest for the following reasons: (i) An earlier
9
vibrational analysis is incomplete, and a number of assignments
are ambiguous. A Raman spectrum over the entire range is
reported, but only 9 of the 15 expected, Raman-active modes
(
II), resulting in a higher π-contribution for the Pt-CO bonds,
trans to the anion and a slight reduction in C-O bond strength.
9
In summary, the previously observed9
,19,26,85-87
differences
are detected. (ii) The previously reported vibrational modes in
the CO-stretching region show a dependence on the solvents
in metal-carbon distances and/or νj (CO) for identical palladium
and platinum carbonyl compounds are clearly induced by the
anionic ligands. They are not observed for the homoleptic cation
9
,26
used
(benzene, toluene, n-heptane, C2H2Cl4) with ν(CO) at
2+ 45
higher wavenumbers in the solid state. (iii) There is to our
knowledge no vibrational analysis for a square planar, seven-
[
M(CO)4] , M ) Pd, Pt (see Table 3), and are hence not due
to intrinsic differences between the Pt-C and Pd-C bonds.
When cis-Pt(CO)2(SO3F)2 is compared to cis-Pt(CO)2Cl2, νav-
9
2
atom molecule. We have recently reported a vibrational
analysis of a related species, square planar, cyclic [Pd2(µ-
-
1
(
CO) is lowered even further by 22 cm , for the latter, which
2+
CO)2] of point group D2h. (iv) Of three cis-Pt(CO)2 derivatives
discussed in this study, only cis-Pt(CO)2Cl2 is sufficiently
volatile at room temperature, to allow a matrix isolation-IR
study. Band proliferation due to factor group splitting, which
may result in misinterpretations, can now be avoided.
reflects differences in the electronegativity of the anionic ligands
-
-
SO3F and Cl . Even lower νj av(CO) values reported for cis-
Pt(CO)2Br29
,19
and cis-Pt(CO)2I2 are consistent with this
19
7
conclusion; however, the Pt-CO bonds in cis-Pt(CO)2Cl2 with
an average distance of 1.897(3) Å are longer than in cis-Pt-
In addition to matrix isolation, vibrational assignments are
assisted by density functional theoretical calculations. Details
(84) Bach, C.; Willner, H.; Wang, C.; Rettig, S. J.; Trotter, J.; Aubke, F.
Angew. Chem., Int. Ed. Engl. 1996, 35, 1974.
(
85) Andreini, B. P.; Belli Dell’Amico, D.; Calderazzo, F.; Venturi, M.
G.; Pelizzi, G. J. Organomet. Chem. 1988, 354, 369.
(89) Sherwood, D. E.; Hall, M. B. Inorg. Chem. 1983, 22, 93.
(90) Lupinetti, A. J.; Jonas, V.; Thiel, W.; Strauss, S. H.; Frenking, G.
Eur. J. Chem. 1999, 5, 2573.
(91) Wang, C.; Lewis, A. R.; Batchelor, R. J.; Einstein, F. W. B.; Willner,
H.; Aubke, F. Inorg. Chem. 1996, 35, 1279.
(92) Wang, C.; Bodenbinder, M.; Willner, H.; Rettig, S. J.; Trotter, J.;
Aubke, F. Inorg. Chem. 1994, 33, 779.
(
(
86) Calderazzo, F.; Belli Dell’Amico, D. Inorg. Chem. 1981, 20, 1310.
87) Belli Dell’Amico, D.; Calderazzo, F.; Zandona, N. Inorg. Chem. 1984,
2
3, 137.
88) Russel, D. R.; Tucker, P. A.; Wilson, G. J. Organomet. Chem. 1976,
04, 387.
(
1

Bis(carbonyl)platinum(II) Derivatives
Inorganic Chemistry, Vol. 39, No. 20, 2000 4431
Table 4. Experimental and Calculated Vibrational Data (cm-1) (Intensities) for cis-Pt(CO)
2 2
Cl and Assignment and Description of Vibrational
Modes
experimental
calculateda
assignment according
approx description
to C2V symmetry
IR(Ar matrix)b
IR(solid)c
Ra(solid)
ν
I
I
(Ra)
∆νd
of modes
e
(IR)
4
331.1 (0.9)
273.1 (0.3)
239.1 (0.2)
638.3 (0.5)
606.9 (0.8)
594.8 (0.4)
4362 (w)
4311 (w)
4285 (vw)
2725 (vw)
2639 (vw)
2ν
1
1
2A
1
4
4
2
2
2
ν
+ ν11
A
1
+ B
2
2ν11
2B
2
ν
ν
ν
1
+ ν12
+ ν13
A
A
1
+ B
+ B
+ B
2
2
1
1
11 + ν12
B
2
2
2
609 (w)
2
2
2
2
2
2
5
4
4
587.3 (0.2)
563.8 (0.8)
171.1 (95)
154.3 (3.7)
126.9 (100)
088.8 (4.6)
ν
ν
ν
ν
ν
ν
ν
ν
ν
11 + ν
7
B
B
A
A′
B
A′
A
A
2
2
+ A
+ B
2
2577 (vw)
2190 (vs)
2175 (sh)
2152 (vs)
2113 (m)
537 (s)
11 + ν13
2
2189 (100)
2174
2146 (75)
2114
2125
2111
2082
2046
524
483
478
(77)
(100)f
(72)
-46
-45
1
1
ν
ν
ν
ν
s
(CO)
13
g
1
′
s
( CO)
(100)h
as(CO)
11
11
2
2
1
3
g
′
as( CO)
46.9 (16)
83.9 (8.3)
68.3 (12)
36.0 (2.8)
541 (0.2)
(6.9)
(0.0)
(3.0)
(0.8)
(7.4)
(0.2)
-23
+26
-6
1
δ(PtCO)
(PtC)
457 (41)
3
1
ν
s
9
B
1
ω(OCPtCO)
4
58 (vs)
434 (0.9)
441
(3.9)
(0.0)
(0.8)
(2.0)
(4.9)
(0.0)
(0.2)
(0.1)
(0.0)
(0.0)
(0.1)
(0.2)
(2.2)
(7.3)
(2.4)
(1.4)
(0.0)
(2.5)
(0.0)
(0.0)
-27
ν
ν
ν
ν
ν
ν
ν
ν
ν
ν
12
B
A
B
A
B
2
A
B
1
A
1
2
F(PtCO)
τ(OCPtCO)
441
7
2
4
3
3
424 (w)
369 (s)
350 (s)
461
356
331
141
96
+25
-31
-32
-19
-21
-24
13
4
2
ν
ν
ν
as(PtC)
i
86.6 (5.3)
370 (98)
346 (21)
160 (115)
1
s
(PtCl)
as(PtCl)
i
62.6 (9.3)
14
5
1
57 (w)
1
δ(ClPtCl)
ω(ClPtCl)
δ(CPtC)
F (ClPtCl)
τ(ClPtCl)
1
16.5 (0.6)
109 (m)
10
6
117 (169)
93
9
7
2
3
15
8
B
A
2
2
a
BP86/ECP2. b Bond position of the most intense matrix site. c s ) strong; m ) medium; w ) weak; sh ) shoulder; v ) very. Difference
d
e
between calculated and IR (matrix) or Raman (solid) wavenumbers. ν ) stretching; s ) symmetric; as ) asymmetric; δ ) deformation; F )
rocking; τ ) twisting; ω ) wagging. Absolute intensity 184.0 Å amu
isotopic pattern strongly disturbed by matrix splitting.
f
4
-1
g
12
13
h
-1 i
.
cis-Pt( CO)( CO)Cl
2
.
Absolute intensity 605.9 km mol . Chlorine
wavenumbers by about 12-18 cm- in the matrix IR spectrum.
1
on the method used and the background to the theoretical
approach have been published recently.48,93 It is, as seen in Table
7
According to the reported molecular structure, there are
4
, now possible to calculate vibrational wavenumbers, as well
significant Cl- - -C secondary contacts, resulting in an extended,
supramolecular structure. These contacts are not possible in
7
as IR and Raman intensities.
The observed IR bands and Raman lines of solid cis-Pt-
an argon matrix, and the platinum-chlorine bonds, which are
(
CO)2Cl2 in the range of 5000-100 cm-1 are listed in Table 4
reported to be very strong, with distances of 2.2863(13) and
7
together with their estimated (IR) or measured (Raman) relative
intensities. They are compared to the infrared band positions
of the most intense matrix sites of cis-Pt(CO)2Cl2 in solid argon
at 12 K and their measured intensities. The experimental
vibrational wavenumbers and intensities are compared to
calculated wavenumbers and IR as well as Raman intensities
of gaseous cis-Pt(CO)2Cl2. The differences between the calcu-
lated and experimental matrix IR or Raman wavenumbers, ∆ν,
are listed as well. A vibrational assignment based on C2V
symmetry of the molecule and an approximate description of
the fundamental modes complete the listings in Table 4.
As can be seen in Table 4, 12 of the 15 fundamentals of
cis-Pt(CO)2Cl2 are detected experimentally. Of the three remain-
ing fundamentals, ν7 (A2) and ν8 (A2) are both only Raman
active, while ν15 (B2) has a very low calculated intensity, with
2.2972(13) Å relative to the ql value of 2.297 Å for 293 cases
83
of platinum bonds to terminal chlorine, become even stronger
in the isolated molecule because of increased Cl-Pt π-bonding
contributions. Increased π-back-bonding to the C-O ligands
is also apparent from shifts to higher wavenumbers for ν(Pt-
C) as well as the Pt-C-O deformation modes, with shifts of
-
1
about 10 cm . More notable however are shifts of the CO-
stretching modes to lower wavenumbers, where in the matrix
-
1
-1
spectrum νs is found at 2171 cm and νas at ∼2127 cm
-
1
compared to 2190 and 2152 cm in solid cis-Pt(CO)2Cl2. The
observed ν(CO) values in the matrix IR spectrum are now very
comparable to solution IR data in various aprotic, weakly
9,19,26
coordinating solvents,
where any intermolecular association
via C- - -Cl contacts should be reduced or even prevented.
The shifts observed for matrix-isolated cis-Pt(CO)2Cl2 are also
detected in the overtones and combination bands observed in
the infrared spectra listed in Table 4, and the value of providing
a complete assignment and vibrational analysis for cis-Pt-
(CO)2Cl2 now becomes apparent in the detection of small
changes in π-bonding within the molecule.
-
1
the last two bands expected below 100 cm , outside the
experimental range.
As expected for cis-Pt(CO)2Cl2 with C2V symmetry, IR bands
and Raman lines of solid samples at room temperature show
very good correspondence. There are interesting differences
between the observed IR and Raman wavenumbers of the solid
and those of matrix-isolated molecules. It is not surprising that
PtCl2 stretching modes, identified by the 35Cl/ Cl isotope
splitting, and the PtCl2 deformation modes are shifted to higher
Agreement between calculated and experimental vibrational
wavenumbers is only fair. As is commonly observed,4
calculated CO-stretching wavenumbers for gaseous molecules
and ions are in general lower than experimental values. In our
5,48,54,93
37
-
1
case they are even lower by about 45 cm than the matrix IR
(93) Jonas, V.; Thiel, W. J. Chem. Phys. 1995, 102, 8474.
wavenumbers. However, interestingly the ν(Pt-C) values for

4432 Inorganic Chemistry, Vol. 39, No. 20, 2000
von Ahsen et al.
calculated Pt(CO)2Cl2 are shifted to higher values relative to
is a more logical choice, consistent with earlier observa-
tions.
-
1
9,19,26
Raman and matrix IR data by about 25 cm . This suggests
increased π-back-bonding in the calculated molecule relative
to the matrix-isolated species. There are also some discrepancies
between calculated and observed intensities of Raman lines.
However, the calculated wavenumbers are very useful in arriving
at a sound vibrational assignment and at locating unobserved
or unobservable fundamentals as discussed above and else-
where.4
Summary and Conclusions
The molecular structure determination of cis-Pt(CO)2(SO3F)2
reported here completes structural studies of square planar
palladium and platinum derivatives synthesized by us. They
44,45
include [M(CO)4][Sb2F11]2
Pd, Pt,
and cis-M(CO)2(SO3F)2, M )
8,54
33,40
90
and c-[Pd2(µ-CO)2](SO3F)2. In all instances
We have in the past43 viewed secondary interionic or
intermolecular interactions as a means to form extended or
supermolecular structures, which provide greater stability toward
loss of CO. It seems now that these significant contacts, at least
the intermolecular and interionic ones, will strengthen the C-O
bonds in solid compounds and may in part be responsible for
extended molecular structures are encountered. Of the so far
33,65,89,90
reported metal carbonyl fluorosulfates,
all but Au(CO)-
65
SO3F are now structurally characterized. In group 10, the
recently reported structure of the longest known metal carbonyl
derivative, cis-Pt(CO)2Cl2, and that of cis-Pd(CO)2(SO3F)2
7
40
allow a useful structural comparison. The complete vibrational
analysis and matrix isolation study of cis-Pt(CO)2Cl2 provides
new insights into π-bonding for the extended molecular
3
3
the high ν(CO) values for cis-M(CO)2(SO3F)2, M ) Pd, Pt,
Au(CO)SO3F,65,66 and Ir(CO)3(SO3F)3. Matrix isolation studies
on any of these molecules would be interesting but certainly
more difficult than in the case of cis-Pt(CO)2Cl2 as described
in this study.
91
7
structure. Despite some efforts, cis-Pt(CO)2F2 remains elusive.
Simple mononuclear organometallic fluorides of low-valent
27a,b
metals continue to remain very rare species.
It seems improbable to attribute the observed two ν(CO)
wavenumbers in matrix-isolated cis-Pt(CO)2Cl2 to temperature
Acknowledgment.
Financial support by Deutsche
10
Forschungsgemeinschaft (DFG), Fonds der Chemischen Indus-
trie (FCI), and the Natural Science and Engineering Research
Council of Canada (NSERC) is gratefully acknowledged.
shifts, because ν(CO) of the gas-phase CO molecule is reduced
-
1
-1 94
in an argon matrix by only 5 cm to 2138 cm . In addition
it would be impossible to attribute the observed positive shifts
for Pt-Cl and Pt-C vibrations to temperature effects. The
proposed redistribution of π-electron density in cis-Pt(CO)2Cl2
Supporting Information Available: X-ray crystallographic file for
cis-Pt(CO) (SO F) in CIF format. This material is available via the
2 3 2
Internet at http://pubs.acs.org.
(94) Schatte, G.; Willner, H.; Hoge, D.; Kn o¨ zinger, E.; Schrems, O. J. Phys.
Chem. 1989, 93, 6025.
IC000280J