A Bis(acetyl)-bridged platinum(II) coordination polymer as a building block for diacetylplatinum(II) complexes and platina-β-diketones

Article abstract of DOI:10.1021/om9000499

bis(acetyl)-bridged complex [{Pt(COMe)2}n](2) has been prepared from the platina-//-diketone [Pt2{(COMe)2H}2(w-Cl)2](1) with hexamethyldisilazane. Reactions of complex 2 with the monodentate P and N donors PPh3, pyrazole (Hpz), pyridine (py), 4-methylpyri

Full text of DOI:10.1021/om9000499

Organometallics 2009, 28, 2485–2493
2485
A Bis(acetyl)-Bridged Platinum(II) Coordination Polymer as a
Building Block for Diacetylplatinum(II) Complexes and
Platina-ꢀ-diketones
Sebastian Schwieger,† Frank W. Heinemann,‡ Christoph Wagner,† Ralph Kluge,†
Cornelia Damm,† Gunter Israel,† and Dirk Steinborn*,†
Institut fu¨r Chemie, Martin-Luther-UniVersita¨t Halle-Wittenberg, Kurt-Mothes-Strasse 2,
06120 Halle (Saale), Germany, and Lehrstuhl fu¨r Anorganische Chemie, UniVersita¨t Erlangen-Nu¨rnberg,
Egerlandstrasse 1, 91058 Erlangen, Germany
ReceiVed January 21, 2009
The bis(acetyl)-bridged complex [{Pt(COMe)2}n] (2) has been prepared from the platina-ꢀ-diketone
[Pt2{(COMe)2H}2(µ-Cl)2] (1) with hexamethyldisilazane. Reactions of complex 2 with the monodentate
P and N donors PPh3, pyrazole (Hpz), pyridine (py), 4-methylpyridine (4-Mepy), and benzylamine (BnNH2)
resulted in the formation of the cis-diacetylplatinum(II) complexes cis-[Pt(COMe)2L2] (L ) PPh3, 3;
Hpz, 5; py, 6a; 4-Mepy, 6b; BnNH2, 7). Reactions with the bidentate N donors 2,2′-bipyridine (bpy),
dimethylglyoxime (H2dmg), and pyridazine (pydz) resulted in formation of the complexes cis-
[Pt(COMe)2(L∩L)] (L∩L ) bpy, 4; H2dmg, 8) and [Pt2(COMe)4(µ-pydz)2] (9), respectively. Furthermore,
complex 2 has been found to react with acids such as HX (X ) Cl, Br), generated in situ from Me3SiX/
H2O, acetylacetone (Hacac), and hexafluoroacetylacetone (Hhfacac) to yield the known platina-ꢀ-diketone
1, the new dinuclear bromo-bridged platina-ꢀ-diketone [Pt2{(COMe)2H}2(µ-Br)2] (10), and new
mononuclear platina-ꢀ-diketones [Pt{(COMe)2H}(L∩L)] (L∩L ) acac, 11; hfacac, 12). All complexes
were characterized by means of microanalysis and IR and NMR spectroscopy. X-ray diffraction analyses
were performed for complexes 10-12, showing a two-dimensional network built up by closed-shell
Pt · · · Pt (d8-d8) interactions and bifurcated hydrogen bonds in crystals of complex 10 as well as infinite
platinum chains built up by closed-shell Pt · · · Pt (d8-d8) interactions in crystals of complexes 11 and 12.
Complexes 8, 11, and 12 have further been analyzed by UV/vis and luminescence spectroscopy in solution
and in the solid state as well as time-resolved photo-emf measurements. Additionally, quantum chemical
studies on the DFT level of theory revealed very strong O-H · · · O hydrogen bonds in the platina-ꢀ-
diketones 10-12 (25.6-27.9 kcal/mol).
be obtained from the reaction of hexachloroplatinic acid with
n-butanol and 1-trimethylsilylalkynes and have been found to
undergo unique sequences of oxidative addition and reductive
elimination processes.6 Furthermore, the catalytic activity of the
thoroughly investigated platina-ꢀ-diketone [Pt2{(COMe)2H}2(µ-
Cl)2] (1) in hydrosilylation reactions has been demonstrated.7
Typical reactivities of 1 toward P and N donors include ligand-
induced bridge cleavage (1 f A, Scheme 1) and oxidative
addition followed by reductive C-H and/or Cl-H elimination
reactions (A f B f C/D).6,8,9 Reactions with a broad variety
of amines as well as with [NMe4]OH and a Proton Sponge led
to platina-ꢀ-diketonates of platina-ꢀ-diketones that can be
considered as analogues to platinum-blue complexes (1 f E,
Scheme 1).10 In these reactions only one moiety of the dinuclear
Introduction
Metalla-ꢀ-diketones can be regarded as organometallic ana-
logues of the enol form of hydrogen-bonded ꢀ-diketones.
Formally they are obtained by replacing the central methine
group of a ꢀ-diketone with a metal fragment. The first metalla-
ꢀ-diketonesa Re(I) complexshas been synthesized by Lukehart
in 1976 by alkylation of an acetyl(carbonyl) complex and its
subsequent protonation.1 Other octahedral metalla-ꢀ-diketones
are known with iron,2 manganese,3 tungsten,4 and iridium.5 In
contrast to the aforementioned metalla-ꢀ-diketones, platina-ꢀ-
diketones are coordinatively and electronically unsaturated
square-planar 16 valence electron (VE) complexes that are
kinetically labile toward ligand substitution reactions. They can
* To whom correspondence should be addressed. E-mail: steinborn@
chemie.uni-halle.de.
(6) (a) Steinborn, D.; Gerisch, M.; Merzweiler, K.; Schenzel, K.; Pelz,
K.; Bo¨gel, H.; Magull, J. Organometallics 1996, 15, 2454–2457. (b)
Steinborn, D. Dalton Trans. 2005, 2664–2671.
(7) Schwieger, S. Ph.D. thesis; Martin-Luther-Universita¨t Halle-Wit-
tenberg, 2008.
† Universita¨t Halle.
‡ Universita¨t Erlangen.
(1) Lukehart, C. M.; Zeile, J. V. J. Am. Chem. Soc. 1976, 98, 2365–
2367.
(2) Lukehart, C. M.; Zeile, J. V. J. Am. Chem. Soc. 1977, 99, 4368–
4372.
(3) Herberhold, M.; Kniesel, H. J. Organomet. Chem. 1987, 334, 347–
358.
(4) Kundel, P.; Berke, H. J. Organomet. Chem. 1988, 339, 103–110.
(5) (a) Garralda, M.; Hernandez, R.; Ibarlucea, L.; Pinilla, E.; Torres,
M. Organometallics 2003, 22, 3600–3603. (b) Acha, F.; Garralda, M. A.;
Hernandez, R.; Ibarlucea, L.; Pinilla, E.; Torres, M. R.; Zarandona, M. Eur.
J. Inorg. Chem. 2006, 3893–3900.
(8) Werner, M.; Bruhn, C.; Steinborn, D. J. Organomet. Chem. 2008,
693, 2369–2376.
(9) (a) Albrecht, C., Ph.D. thesis, Martin-Luther-Universita¨t Halle-
Wittenberg, 2006. (b) Albrecht, C.; Wagner, C.; Steinborn, D. Z. Allg. Anorg.
Chem. 2008, 634, 2858–2866.
(10) (a) Steinborn, D.; Gerisch, M.; Heinemann, F. W.; Bruhn, C. Chem.
Commun. 1997, 843–844. (b) Gerisch, M.; Bruhn, C.; Porzel, A.; Steinborn,
D. Eur. J. Inorg. Chem. 1998, 1655–1659. (c) Gerisch, M.; Bruhn, C.;
Steinborn, D. Polyhedron 1999, 18, 1953–1956.
10.1021/om9000499 CCC: $40.75
2009 American Chemical Society
Publication on Web 03/25/2009

2486 Organometallics, Vol. 28, No. 8, 2009
Schwieger et al.
Scheme 1. Reactivity of the Platina-ꢀ-diketone [Pt2{(COMe)2H}2(µ-Cl)2] (1) toward P and N Donors with and without the
Presence of a Base (1 f A/B/D and 1 f A/B/C) and toward Bases B (1 f E)
Scheme 2. Formation of the Diacetylplatinum(II) Coordina-
tion Polymer 2
Scheme 3. Complex 2 as a Building Block for the cis-
Diacetylplatinum(II) Complexes 3-9
platina-ꢀ-diketone 1 is deprotonated, while the other one remains
intact. The use of an excess of amines did not lead to identifiable
products. In this work we report on the synthesis of a new
bis(acetyl)-bridged platinum(II) coordination polymer, 2, that
was obtained by complete deprotonation of the platina-ꢀ-
diketone 1 using hexamethyldisilazane. The reactivity of this
complex was explored, showing pathways to new platina-ꢀ-
diketones with interesting structural properties and diacetyl
platinum(II) complexes.
it can be assumed that it is a cyclotetramer. Thus, the results of
both characterizations are in agreement but reflect only the solute
part of 2. Microanalyses of all batches of 2 exhibited minor
residues of Cl and N (ca. 2%). This might be due to residual
amounts of NH4Cl and/or end groups of linear oligomers.
Results and Discussion
Formation of [{Pt(COMe)2}n] (2). Reaction of the dinuclear
platina-ꢀ-diketone [Pt2{(COMe)2H}2(µ-Cl)2] (1) with hexa-
methyldisilazane in dichloromethane resulted in the precipitation
of a colorless powder, 2 (Scheme 2). The variation of the ratio
of educts from 1:1 to 1:100 did not have any effect on the
product obtained. The coordination polymer 2 was formed by
formal cleavage of HCl from 1; thus hexamethyldisilazane acted
both as a Brønsted base and as a chloride acceptor. In accordance
with that, chlorotrimethylsilane and its hydrolysis product
(hexamethyldisiloxane) were found as further products (NMR,
GC-MS). Complex 2 was found to react with PPh3 and 2,2′-
bipyridine (bpy), forming the known complexes cis-[Pt-
(COMe)2(PPh3)2] (3) and cis-[Pt(COMe)2(bpy)] (4) in 86% and
93% isolated yield, respectively (Scheme 3).
Complex 2 proved to be only barely soluble in all common
solvents, thus preventing the recrystallization and its precise
characterization. From freshly prepared solutions in CDCl3 it
was possible to obtain NMR spectra (1H, 13C) showing that the
two acetyl ligands are NMR spectroscopically identical. In ESI
mass spectra a tetranuclear aggregate with Na+ ([{Pt(COMe)2}4]
+ Na+) was identified. Since there were no end groups found,
Reactivity of [{Pt(COMe)2}n] (2). Apart from the two above-
mentioned complexes 3 and 4 further diacetylplatinum(II)
complexes (5-9) could be obtained in the reactions of complex
2 with pyrazole (Hpz), pyridine (py), 4-methylpyridine
(4-Mepy), benzylamine (BnNH2), dimethylglyoxime (H2dmg),
and pyridazine (pydz) (Scheme 3). Complexes 6a and 6b have
been found to be unstable in solution due to ligand loss and
subsequent CO extrusion from an acetyl ligand, yielding
[Pt(COMe)Me(CO)L] (L ) py, 4-Mepy). This reaction pro-
ceeded faster with 6b, thus preventing its isolation in a pure
state. Both complexes proved to be stable at room temperature
over a period of several days in the presence of a 3-fold excess
of the pyridine ligand. This finding supports the proposed
mechanism that a ligand is eliminated prior to CO extrusion.
An analogous decomposition behavior has been observed for
L ) BnNH2 (complex 7). As the bipyridine complex,8 the
dimethylglyoxime-coordinated complex 8 is highly stable in the
solid state (fp: 192-194 °C) as well as in solution. No
decomposition has been observed in dichloromethane solution
over a period of several days.

Bis(acetyl)-Bridged Platinum(II) Coordination Polymer
Organometallics, Vol. 28, No. 8, 2009 2487
Scheme 4. Complex 2 as a Building Block for the Platina-ꢀ-diketones 1 and 10-12
The identities of all isolated complexes were confirmed by
microanalyses as well as NMR (1H, 13C, 195Pt) and IR
Å)11 and C-O single bond lengths (median in ethers: 1.42 Å),11
reflecting a partial C-O double bond character, as expected
for a hydrogen-bonded hydroxycarbene-acyl system. The in-
tramolecular O1 · · · O2 distance (2.42(2) Å) indicates strong
hydrogen bonds. In addition, relatively short intermolecular
O2 · · · O2′ and O1 · · · O2′ distances (2.99(2)/3.36(2) Å) show
that these are actually part of a pair of bifurcated hydrogen bonds
(O1, O2, O2′ and O1′, O2′, O2, Figure 1), thus forming one-
dimensional ribbons in crystals of 10. Because the hydrogen
atoms involved in the hydrogen bonds could not be located in
the electron density map, the discussion has to be restricted to
the positions of the oxygen atoms. Furthermore, Pt · · · Pt closed-
shell d8-d8 interactions (d(Pt · · · Pt) ) 3.601(1) Å) give rise to
a staircase-like packing of the dinuclear platina-ꢀ-diketone
molecules 10, thus connecting the hydrogen-bonded ribbons in
a second dimension (Figure 2). In crystals of the analogous
chloro-bridged platina-ꢀ-diketone 1 only a packing via Pt · · · Pt
closed-shell d8-d8 interactions was found, however being
stronger than those in 10, as indicated by shorter Pt · · · Pt
distances (3.352(1) Å).12
Structuresof[Pt{(COMe)2H}(acac)](11)and[Pt{(COMe)2H}-
(hfacac)] (12). The molecular structures of complexes 11 and
12 are given in the Figures 3 and 4. Selected distances and
angles are given in the figure captions. Complex 11 exhibits
crystallographically imposed C2V symmetry. The backbone of
complex 12 (Pt, O3, O4, C1-C9) was found to be planar, and
due to crystal symmetry all atoms above and below that plane
are disordered over two equally occupied positions (see
Experimental Section). In both complexes the platinum atoms
are coordinated in a square-planar manner (sum of angles around
Pt: 360.0/360.0°, 11/12). In complex 11 all non-hydrogen atoms
are situated in the molecular plane. In complex 12 the largest
deviation of non-hydrogen atoms (except F atoms) from the
coordination plane is realized by O2 (0.225(9) Å). The Pt-C
distances (1.936(4)-1.956(4) Å) are within the typical range
for Pt-C distances of other platina-ꢀ-diketones (median: 1.956
Å, lower/upper quartile: 1.938/1.967 Å, n ) 20).13 The C-O
bond lengths in the platina-ꢀ-diketone as well as in the
acetylacetonato moieties (1.263(6)-1.293(5) Å) are between
typical lengths of C-O single (median in ethers: 1.42 Å)11 and
CdO double bonds (median in ketones: 1.21 Å),11 indicating a
partial double-bond character in these bonds. Compared to other
structurally characterized acetylacetonato platinum(II) complexes
(median: 2.019 Å, lower/upper quartile: 2.000/2.033 Å, n )
186),13 the Pt-O distances in 11 (2.108(3) Å) and in 12
(2.122(2)/2.132(3) Å) are significantly longer. Those in 12 are
1
spectroscopically. The H and 13C NMR spectra clearly gave
proof of the constitution (see Experimental Section) of com-
3
2
plexes 5-9. Their JPt,H (22.7-25.5 Hz) and JPt,C/1JPt,C
(308.2-378.2/1268.4-1323.5 Hz) coupling constants are in the
same ranges as those of other cis-diacetylplatinum(II) com-
plexes.8 This indicates in complexes 5-9 a cis arrangement of
the two acetyl ligands, as also expected because of their high
trans influence. The dinuclear structure of the pyridazine-bridged
complex 9 was proved by ESI-MS measurements showing
[M + H]+ and [M + Na]+ peaks in methanol solution. Complex
9 was found to be only barely soluble in common organic
solvents but, interestingly, easily soluble in water, where it
decomposes within several hours at room temperature.
Furthermore, complex 2 was found to react with HCl in a
reverse reaction (with respect to the formation of 2), yielding
the dinuclear platina-ꢀ-diketone 1 (Scheme 4). The analogous
reaction with HBr was not successful and resulted in decom-
position of the reaction solution to platinum black. However,
the reaction with stoichiometric amounts of HX, generated in
situ from an excess of the corresponding SiMe3X (X ) Cl, Br)
and H2O (n(Me3SiX):n(H2O) ) 4:1), resulted in the formation
of the known platina-ꢀ-diketone 1 and the bromo-bridged
platina-ꢀ-diketone [Pt2{(COMe)2H}2(µ-Br)2] (10, Scheme 4).
Complex 10 was found to decompose much faster in air than
the chloro-bridged complex 1 (2 min vs >30 min). Thus, the
synthesis of 10 has to be performed under strictly water-free
conditions as realized with an excess of Me3SiBr. The identity
of complex 10 was proved by microanalysis, NMR spectros-
copy, and an X-ray crystal structure determination.
Treatment of complex 2 with acetylacetone (Hacac) resulted
within 11/2 days in a dichroic violet-green precipitate, which
could be identified as the mononuclear platina-ꢀ-diketone
[Pt{(COMe)2H}(acac)] (11). Likewise, the reaction of complex
2 with hexafluoroacteylacetone (Hhfacac) in dichloromethane
resulted in the formation of [Pt{(COMe)2H}(hfacac)] (12) as a
red crystalline substance (Scheme 4). Both complexes could
be characterized by microanalyses, NMR, IR and UV/vis
spectroscopy, and X-ray crystal structure determinations.
Structure of [Pt2{(COMe)2H}2(µ-Br)2] (10). The molecular
structure of complex 10 is shown in Figure 1; selected distances
and angles are given in the caption. The dinuclear molecule
exhibits crystallographically imposed Ci symmetry. The platinum
atom is square-planar coordinated (sum of angles around Pt:
359.9°), and overall the molecule is planar (largest deviation
of a non-hydrogen atom (C2) from the complex plane: 0.34(2)
Å). The bond lengths in the platina-ꢀ-diketone moieties in the
bromo- and chloro-bridged complexes 10 and 1 do not
significantly differ. The C-O distances (1.26(2)/1.27(3) Å) are
between typical CdO double bond (median in ketones: 1.21
(11) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1–S19.
(12) Steinborn, D.; Gerisch, M.; Hoffmann, T.; Bruhn, C.; Israel, G.;
Mu¨ller, F. W. J. Organomet. Chem. 2000, 598, 286–291.
(13) Allen, F. H. Acta Crystallogr., Sect. B 2002, 58, 380–388.

2488 Organometallics, Vol. 28, No. 8, 2009
Schwieger et al.
Figure 1. Molecular structure of [Pt2{(COMe)2H}2(µ-Br)2] (10). Ellipsoids are shown at the 50% probability level. Selected distances (Å)
and angles (deg): Pt-Br 2.580(2), Pt-Br′ 2.575(2), Pt-C1 1.96(2), Pt-C3 1.98(2), C1-O1 1.27(2), C3-O2 1.26(2), O1 · · · O2 2.42(2),
O2 · · · O2′ 2.99(2), O1 · · · O2′ 3.36(2), Br-Pt-Br′ 81.22(6), C1-Pt-C3 91.0(8), Pt-Br-Pt′ 98.78(6).
Figure 2. Packing of molecules with closed-shell platinum d8-d8 interactions in crystals of 10. d(Pt · · · Pt′′) ) 3.601(1) Å. Distance between
coordination planes: 3.48 Å.
Figure 3. Molecular structure of [Pt{(COMe)2H}(acac)] (11).
Figure 4. Molecular structure of [Pt{(COMe)2H}(hfacac)] (12).
Ellipsoids are shown at the 50% probability level. All F-atoms, all
H-atoms of the methyl groups, and O1 and O2 are disordered over
two equally occupied positions due to a mirror plane identical to
the complex plane. In all cases only one of the two disordered atoms
is shown. Selected distances (Å) and angles (deg): Pt-C1 1.956(4),
Pt-C3 1.936(4), Pt-O3 2.122(2), Pt1-O4 2.132(3), C1-O1
1.265(6), C3-O2 1.288(5), C5-O3 1.271(5), C7-O4 1.269(5),
O1 · · · O2 2.389(4), O1 · · · O2′ 2.419(5), O3-Pt-O4 86.6(1),
C1-Pt-C3 92.0(2).
Ellipsoids are shown at the 50% probability level. Selected distances
(Å) and angles (deg): Pt-C4 1.943(5), Pt-O1 2.108(3), C4-O2
1.263(6), C1-O1 1.293(5), C1-C2 1.391(5), O2 · · · O2′ 2.408(5),
C4-Pt-C4′ 91.5(2), O1-Pt-O1′ 87.9(1).
even the longest ones known up to now. As for other platina-
ꢀ-diketones, the O · · · O distance of 2.408(5) Å in complex 11
indicates a strong O-H · · · O hydrogen bond. Due to disordered
O1 and O2 atoms in complex 12, two values have to be
considered (2.389(4)/2.419(5) Å), pointing also to strong
hydrogen bonds.
linear (Pt · · · Pt′ · · · Pt″ angles: 179.41° and 175.32° for 11 and
12, respectively).
Molecules of complexes 11 and 12 are stacked in the crystals
via Pt · · · Pt closed-shell d8-d8 interactions (Figure 5), forming
one-dimensional platinum chains. Neighbored molecules are
related by an inversion center positioned on the Pt · · · Pt′ axis.
The Pt · · · Pt′ distances (3.1601(6) Å, 11; 3.2855(1) Å, 12) are
within the typical range of closed-shell interactions of Pt(II)
(in Krogmann’s salts: 3.09-3.60 Å).14 As found in Krogmann’s
salts, the arrangements of the Pt atoms in the chains are nearly
UV/Vis Characterization. Previously we have reported on
the UV/vis properties of dinuclear platina-ꢀ-diketones of the
type [Pt2{(COR)2H}2(µ-Cl)2] (R ) Me, Et, n-Pent, n-Hex,
(CH2)4Ph)12 showing in the solid state an absorption band in
the visible light region that is absent in solution spectra. It was
concluded that this is due to the staircase-like packing of the
dinuclear platina-ꢀ-diketone molecules in crystals (analogous
to that in crystals of 10) containing alternating intermolecular
Pt · · · Pt d8-d8 interactions and intramolecular Pt-Cl-Pt bridges.
(14) Krogmann, K. Angew. Chem. 1969, 81, 10–17.

Bis(acetyl)-Bridged Platinum(II) Coordination Polymer
Organometallics, Vol. 28, No. 8, 2009 2489
bond energies can be adequately described by comparing the
electronic energies of the equilibrium structure of the hydrogen-
bonded system with an “open” structure that was obtained by
rigid rotation of the O-H hydrogen atom around the C-O bond
by 180° and subsequent relaxation of all bond lengths and angles
(but dihedral angles kept frozen). In all cases the calculated
equilibrium structures (10calc-12calc) are in good agreement with
the experimentally found structures (see Table 2), thus prov-
ing the validity of the quantum chemical model used. In Figure
7 the calculated hydrogen-bonded and the non-hydrogen-bonded
(“open”) structures 11calc/11*calc are shown as an example. The
hydrogen bonds in all three platina-ꢀ-diketones 10-12 are very
strong (25.6-27.9 kcal/mol, see Table 2), being nearly twice
as strong as that in acetylacetone (16.1 kcal/mol).16 Essentially
the same values were found in the dinuclear platina-ꢀ-diketones
1 and 10 (25.7 vs 25.6 kcal/mol); thus no influence of the
bridging halogen atoms (Cl vs Br) was observed. Furthermore,
the hydrogen bonds in the neutral mononuclear complexes 11
and 12 (27.9/26.6 kcal/mol) proved to be as strong as that
in the mononuclear anionic platina-ꢀ-diketone ([Pt{(COMe)2H}-
Cl2]-, 27.2 kcal/mol) and significantly stronger as that in
the mononuclear cationic platina-ꢀ-diketone ([Pt{(COMe)2H}-
(bpy)]+, 19.6 kcal/mol).16
Concluding Remarks. In this work the reactivity of the
chloro-bridged platina-ꢀ-diketone 1 toward hexamethyldisila-
zane was shown forming a new platinum coordination polymer
2 having bis(acetyl)-bridged PtII(µ-COMe)2PtII building blocks.
This reaction requires not only the deprotonation of the platina-
ꢀ-diketone unit but also the formation of two free coordination
sites on the platinum fragment. Thus, the substrate (NH(SiMe3)2)
has to be a Brønsted base, a chloride acceptor, and may only
be a weak donor to prevent the cleavage of the weak Pt-Oacetyl
bonds in 2. Obviously, hexamethyldisilazane fulfills all these
three requirements. Additionally, the formation of the oligo-
meric/polymeric complex 2 is also favored by its insolubility.
On the other hand, the analogous reactions with alkyl and aryl
amines being stronger nucleophiles andsif anysweaker chloride
acceptors resulted in a partial deprotonation of 1 only (1 f E,
Scheme 1) and a decomposition by using an excess of amines,
respectively.10
The deprotonation of 1 yielding the bis(acetyl)-bridged
coordination polymer 2 is, in general, reversible, as shown in
the reaction of 2 with HCl, Me3SiX/H2O (X ) Cl, Br), and
Hacac/Hhfacac. These reactions opened up a way to synthesize
the new platina-ꢀ-diketones 10-12. The bromo-bridged com-
plex 10 is the first dinuclear platina-ꢀ-diketone having bridge
atoms other than Cl. It is worth mentioning that other ways to
synthesize 10 failed: (i) Reactions of H2[PtX6] · xH2O in n-BuOH
with Me3SiCtCSiMe3 resulted for X ) Cl in the formation of
complex 1 but for X ) Br in the decompostion with formation
of platinum black.17 (ii) Reactions of cis-[PtX2{C(OMe)Me}2]
with water were found for X ) Cl to result in the quantitative
formation of the platina-ꢀ-diketone 1, whereas for X ) Br a
slow decomposition occurred.18 Complexes 11 and 12 are the
first platina-ꢀ-diketones having O donors as coligands. Interest-
ingly, the synthesis of 11 starting from 1 and Hacac failed, most
likely because the nucleophilicity of Hacac is too low for
cleavage of the Pt-Cl-Pt bridges.
Figure 5. Packing of molecules in crystals of 11 (left) and 12 (right).
d(Pt · · · Pt) ) 3.1601(6) Å (11) and 3.2855(1) Å (12), Pt · · · Pt · · · Pt:
179.41° (11) and 175.32° (12).
Furthermore, the emissions at λmax ) 555 nm after excitation
of the platina-ꢀ-diketones were ascribed to ligand field (d8-d8)
electronic excited states of the isolated intermolecular Pt · · · Pt
interactions. The structural characteristics and the intensive
colors of complexes 8 (blue), 11 (dichroic green-violet), and
12 (red) in the solid state prompted us to perform UV/vis
analyses, showing broad absorption bands in the visible light
region in solid state spectra but no requisite absorptions in
solution spectra (Table 1). Furthermore, as shown in Table 1
in complexes 1 (for comparison), 11, and 12 λmax of the longest
wavelength absorption was found to correlate with the structur-
ally determined intermolecular Pt · · · Pt distance. In contrast to
the platina-ꢀ-diketones mentioned above, no emissions were
found in the visible light region for complexes 8, 11, and 12.
On the other hand, all three complexes show photo-emf signals
and thus a spatial separation of the charge carriers e-/h+ in the
solids after pulse exposure (Figure 6). The principle for the
origin of a photo-emf with the measurement arrangement is
given in ref 15. While complexes 8 and 11 behave like n-type
photoconductors (large positive photo-emf signals Umax), com-
plex 12 behaves like a p-type photoconductor (small negative
photo-emf signal Umax). The efficiency of the charge separation
decreases in the following sequence: complex 8 . 11 > 12
(Umax, Table 1). Additionally, the rate of charge carrier
recombination is lower in complex 8 as compared to complex
11 (k1/k2, Table 1). From the electronic properties of complex
8, whose solid state structure is unknown until now, it can be
concluded that in crystals infinite · · · Pt · · · Pt · · · chains are found
that are broken up in dichloromethane solutions. The maximum
of absorption in the visible light region (λmax ) 637 nm)
indicates that the Pt · · · Pt distance may be shorter (<3.16 Å)
than those in complexes 11 and 12.
Hydrogen Bond Strength in the Platina-ꢀ-diketones. High-
level DFT calculations (B3LYP/6-311++G(d,p)) of the di-
nuclear bromo-bridged platina-ꢀ-diketone 10 as well as of the
mononuclear acetylacetonato-coordinated platina-ꢀ-diketones 11
and 12 were performed to determine the strength of the
intramolecular hydrogen bonds (∆Ehb) according to the method
introduced in ref 16. There it was shown that in enol forms of
organic ꢀ-diketones and in metalla-ꢀ-diketones the hydrogen
All these reactions as well as the synthesis of [Pt-
{(COMe)2H}(dppe)][BF4] from [Pt(COMe)2(dppe)]/H[BF4]9
(15) (a) Israel, G.; Mu¨ller, F. W.; Damm, C.; Harenburg, J. J. Inf. Rec.
1997, 23, 559–584. (b) Damm, C.; Israel, G.; Hegmann, T.; Tschierske, C.
J. Mater. Chem. 2006, 16, 1808–1816.
(17) Werner, M., Ph.D. thesis, Martin-Luther-Universita¨t Halle-Witten-
berg, 2007.
(18) Werner, M.; Lis, T.; Bruhn, C.; Lindner, R.; Steinborn, D.
Organometallics 2006, 25, 5946–5954.
(16) Steinborn, D.; Schwieger, S. Chem.sEur. J. 2007, 13, 9668–9678.

2490 Organometallics, Vol. 28, No. 8, 2009
Schwieger et al.
Table 1. UV/Vis and Luminescence Spectroscopic Data as well as Kinetic Parameters from Photo-emf Measurementsa of Complexes
[Pt(COMe)2L2] (8) and [Pt{(COMe)2H}L2] (1, 11, 12)
absorption
(solid state)
λmax [nm]
absorption
(solution)
λmax [nm]
emission
(solid state)
λmax [nm]
0
0
complex
L2
d(Pt · · · Pt) [Å]
color
blue
Umax U1 /U2 [mV] k1/k2 [s-1
]
c
c
c
8
H2dmg
acac
hfacac
µ-Cl/µ-Cl
637 (m, br), 369 (s)
green-violet 591 (m, br), 506 (sh), 327 (s) 341, 307
424, 355, 321
10.3
2.3
28.6/-18.3
10.2/-7,9
≈0
49.4/30.4
154.6/110.7
11
12
1b
3.160(1)
3.2855(1)
3.352(1)
red
yellow
514 (m, br), 349 (sh), 303 (s) 323, 299
412 334, 305
-0.4
0
555
a
Evaluated according to a biexponential decay: U(t) ) U1 exp(-k1t) + U2 exp(-k2t). b From ref 12. c No emission was observed.
0
0
Experimental Section
General Comments. All reactions and manipulations were
carried out under argon using standard Schlenk techniques. Solvents
were dried prior to use (CHCl3, CH2Cl2 over CaH2, diethyl ether,
benzene, toluene, n-pentane over Na/benzophenone, and acetone
over 4 Å molecular sieves) and freshly distilled. NMR spectra (1H,
13C, 19F, 31P, 195Pt) were recorded at 27 °C on Varian Gemini 200,
VXR 400, and Unity 500 spectrometers. Chemical shifts are relative
to solvent signals (CDCl3, δH 7.24, δC 77.0; CD2Cl2, δH 5.32, δC
53.8; C6D6, δH 7.15, δC 128.0) as internal references; δ(19F), δ(31P),
and δ(195Pt) are relative to external CFCl3 (δF 0.0), H3PO4 (85%)
(δP 0.0), and H2[PtCl6] in D2O (δPt 0.0), respectively. When
necessary, assignments of signals were verified by 1H,1H and 13C,1H
COSY experiments. Microanalyses (C, H, N, Cl, Br) were
performed in the Microanalytical Laboratory of the University of
Halle using a CHNS-932 (LECO) as well as a VARIO EL
(Elementaranalysensysteme) elemental analyzer for C, H, and N
and a volumetric analysis (Scho¨ninger) for Cl and Br. IR spectra
were recorded on a Mattson 5000 Galaxy FT-IR spectrometer using
CsBr or KBr pellets and a Tensor 27 FT-IR spectrometer using an
ATR sampler, respectively. Hexachloroplatinic acid was com-
mercially available (m&k GmbH, 47.4% Pt). The platina-ꢀ-diketone
[Pt2{(COMe)2H}2(µ-Cl)2] (1) was prepared according to a previ-
ously published procedure.20 Positive and negative ESI-MS were
obtained from a Finnigan Mat. LCQ. The sample solutions were
introduced continuously via a syringe pump (flow: 8 µL/min, sheath
gas: N2, ESI spray voltage: 4.1 kV, capillary temperature: 200 °C,
capillary voltage: 34 kV). GC-MS analysis was performed on an
HP 5890 Series II/HP-5972 MSD (Hewlett-Packard) (column: HP5-
MS; 30 m). UV/vis spectra of complexes in dichloromethane
solution were performed on a Varian Cary 4E. Reflection data of
the complexes in the solid state were collected on a Perkin-Elmer
Lambda 19 and recalculated to transmission data following the
Kubelka-Munk function.21 Emission measurements were taken on
a Perkin-Elmer LS 50B fluorescence spectrometer (λexc. ) 400 nm).
Photo-emf measurements were performed using a home-built
apparatus consisting of a nitrogen pumped dye laser UDL 210
(Lasertechnik Berlin, > 30 µJ per pulse, λexc. ) 337 nm, 2.7 ×
1013 quanta/flash, τ1/2 ) 0.5 ns, registration via 200 MHz digital
storage oscilloscope Philips PM3394).15 For photo-emf measure-
ments pellets were prepared from powdered samples by applying
high pressure.
Figure 6. Time-resolved photo-emf signals for the complexes
[Pt(COMe)2(H2dmg)] (8) and [Pt{(COMe)2H}(L∩L)] (L∩L ) acac,
11; hfacac, 12).
give proof that via protonation of diacetyl platinum complexes
platina-ꢀ-diketones are accessible. The analogous reaction, the
protonation of anionic diacetyl complexes [M(COMe)2Lx]- (M
) Re, Fe; L ) CO, Cp) having carbonyl and cyclopentadienyl
coligands, is the general (and only) way how metalla-ꢀ-diketones
[M{(COMe)2H}Lx] were obtained by Lukehart.19 Due to the
electronic saturation (18 VE) of Lukehart’s complexes, the attack
of the proton is expected to occur directly on the oxygen atoms
of the acetyl ligands. In the case of the electronically nonsat-
urated (16 VE) diacetyl platinum(II) complexes the protonation
of the platinum atom in the sense of an oxidative addition
reaction followed by a proton shift in the sense of a reductive
elimination forming the platina-ꢀ-diketone moiety appears to
be an alternative. On grounds of the experimental data neither
of these two reaction ways can be favored.
Although in crystals of platina-ꢀ-diketones Pt · · · Pt (d8-d8)
closed-shell interactions were frequently found,12 so far no
infinite · · · Pt · · · Pt · · · chains were observed as in Krogmann’s
salts.14 The first examples for this are the mononuclear acety-
lacetonato-coordinated platina-ꢀ-diketones 11 and 12 described
herein. Both optical and photoelectrical properties of the
complexes do agree with the polymeric Pt · · · Pt chain structure.
Thus, the bis(acetyl)-bridged platinum(II) coordination polymer
2 proved to be a suitable starting complex for the synthesis not
only of cis-diacetylplatinum(II) complexes having N donors as
coligands (4-9) but alsosin the formal reverse of its building
reactionsof new platina-ꢀ-diketones (10-12) that have not been
accessible in “conventional” ways.
Synthesis of [{Pt(COMe)2}n] (2). At -78 °C hexamethyldisi-
lazane (0.375 g, 2.323 mmol) was added to a solution of 1 (1.475
g, 2.323 mmol) in dichloromethane (5 mL) with stirring. Then, the
reaction mixture was stirred at room temperature for an additional
10 min, whereupon 2 precipitated as colorless powder. The volume
of the reaction mixture was reduced in vacuo up to half. Then, the
precipitate was filtered at -50 °C and washed with acetone (5 ×
10 mL) at the same temperature. Finally, the product was dried in
vacuo. Yield: 1.084 g (83%). Tdec: 140 °C. Anal. Found: C, 16.74;
H, 2.81; Cl, 2.29; N, 2.24. C4H6O2Pt (281.17) requires: C, 17.09;
1
3
H, 2.15. H NMR (200 MHz, CDCl3): δ 2.40 (s+d, JPt,H ) 17.6
(20) Albrecht, C.; Schwieger, S.; Ru¨ffer, T.; Bruhn, C.; Lis, T.;
Steinborn, D. Organometallics 2007, 26, 6000–6008.
(21) Kubelka, P.; Munk, F. Z. Technol. Phys. 1931, 12, 593.
(19) (a) Lukehart, C. M. Acc. Chem. Res. 1981, 14, 109–116. (b)
Lukehart, C. M. AdV. Organomet. Chem. 1986, 25, 45–71.

Bis(acetyl)-Bridged Platinum(II) Coordination Polymer
Organometallics, Vol. 28, No. 8, 2009 2491
Table 2. Atom Distances (in Å) and Angles (in deg) as well as Relative Electronic Energies of the Calculated Equilibrium Structures
10calc-12calc and the Requisite “Open” Conformers 10*calc-12*calc in Comparison with Crystal Structure Data of Complexes 10-12
10
10calc
10*calc
11
11calc
11*calc
12
12calc
12*calc
Pt-C
1.96(2)/1.98(2) 1.972/2.003 1.947/2.037 1.943(5) 1.960/1.989 1.964/2.002 1.936(4)/1.956(4)
1.27(2)/1.26(2) 1.271/1.238 1.302/1.201 1.266(5) 1.273/1.244 1.302/1.209 1.288(5)/1.265(6)
1.960/1.988 1.961/2.029
1.267/1.240 1.296/1.203
1.090/1.339 0.972/-
C-O
O-H/O · · · H
O · · · O
1.075/1.361 0.971/-
1.087/1.343 0.972/-
2.42(2)
2.405
18/22
0.0
2.413
18/22
51.1
2.407(4) 2.406
3
2.421
9/8
2.389(4)/2.419(5)a 2.405
6/4
2.436
1/1
ꢁ
carbene/ꢁacetyl 12/9
9/8
0.0
1/1
0.0
∆E
27.9
26.6
a Two values are possible due to disorders of O1 and O2 (see text).
H3-Hpz), 7.23 (s, 2H, H5-Hpz), 14.68 (s (br), 2H, NH). 13C NMR
(CDCl3, 50 MHz): δ 43.7 (s+d, 2JPt,C ) 331.7 Hz, COCH3), 105.3
(s, C4-Hpz), 129.8 (s, C3-Hpz), 139.8 (s+d, 2JPt,C ) 34.9 Hz, C5NPt),
1
234.2 (s+d, JPt,C ) 1293.4 Hz, COMe). 195Pt NMR (CDCl3, 107
MHz): δ -3194 (s). IR (CsBr): ν 3116 (m), 3049 (m), 2962 (m),
2794 (w), 2627 (w), 1565 (s), 1431 (w), 1404 (s), 1366 (m), 1330
(m), 1151 (m), 1119 (s), 1102 (s), 1057 (s), 941 (m), 905 (m), 878
(m), 757 (s), 618 (s), 363 (m), 309 (m) cm-1. UV/vis (solid): λmax
561 (w), 365 (s), 293 (s, br), 230 (s, br) nm. UV/vis (in CH2Cl2):
λmax (ꢀ/L mol-1 cm-1) 350 (900), 279 (2800), 246 (5000), 230
(7000) nm.
Figure 7. Structures of calculated hydrogen-bonded platina-ꢀ-
diketone 11calc (left) and non-hydrogen-bonded “open” conformer
11*calc (right).
Synthesis of cis-[Pt(COMe)2(py)2] (6a). At -70 °C pyridine
(131 µL, 1.624 mmol) was added to complex 2 (114 mg, 0.406
mmol) in dichloromethane (5 mL) with stirring. The reaction
mixture was warmed to room temperature with stirring within 30
min. Afterward, the volume of the reaction mixture was reduced
in vacuo (2.5 mL) and diethyl ether (10 mL) was added. The
resulting colorless precipitate was filtered, washed with diethyl ether
(10 mL), and dried in vacuo. Yield: 117 mg (66%). Tdec: 77-79
°C. Anal. Found: C, 37.52; H, 3.84; N, 6.50. C14H16N2O2Pt (439.09)
requires: C, 38.26; H, 3.67; N, 6.38. 1H NMR (200 MHz, CDCl3):
Hz, 6H, COCH3). 13C NMR (50 MHz, CDCl3): δ 41.7 (s, COCH3),
242.0 (s, COCH3). IR (CsBr): ν 3420 (w), 3153 (m), 3052 (m),
2983 (m), 1607 (s), 1563 (vs), 1409 (s), 1339 (m), 1151 (m), 1121
(s), 651 (w), 344 (w) cm-1. ESI-MS (negative mode, MeOH): m/z
(obsd/calcd %) {[{Pt(COMe)2}4]+Cl}-: 1156 (8/23), 1157 (17/
51), 1158 (36/81), 1159 (100/100), 1160 (98/100), 1161 (61/88),
1162 (17/67), 1163 (9/47). MS/MS (1161): m/z 1131, 1103, 1073,
879, 851. ESI-MS (positive mode, MeOH): m/z (obsd/calcd %)
{[{Pt(COMe)2}4]+Na}+: 1143 (10/9), 1144 (33/27), 1145 (36/56),
1146 (53/83), 1147 (100/100), 1148 (75/89), 1149 (48/72), 1150
(29/50).
Synthesis of cis-[Pt(COMe)2(PPh3)2] (3). Triphenylphosphine
(150 mg, 0.570 mmol) was added to a suspension of complex 2
(80 mg, 0.285 mmol) in dichloromethane (5 mL) and stirred for
20 min at 0 °C. After an additional hour of stirring at room
temperature the volume of the reaction mixture was reduced in
vacuo (2 mL). Addition of n-pentane/diethyl ether (3:1, 15 mL)
resulted in the formation of a light yellow precipitate that was
filtered, washed with n-pentane (10 mL), and dried in vacuo. Yield:
198 mg (86%). Tdec: 64 °C. Anal. Found: C, 59.06; H, 4.76;
C40H36O2P2Pt (805.74) requires C, 59.63; H, 4.50. 1H, 13C, 31P, and
195Pt NMR spectra were found as reported in ref 9b.
Synthesis of cis-[Pt(COMe)2(bpy)] (4). 2,2′-Bipyridine (33 mg,
0.21 mmol) was added at 0 °C to a suspension of complex 2 (60
mg, 0.21 mmol) in dichloromethane (5 mL), and the resulting
mixture was stirred for 1 h at room temperature. Then the volume
of the red solution was reduced in vacuo (2 mL), and diethyl ether
(10 mL) was added slowly. The resulting red precipitate was filtered,
washed with diethyl ether (2 × 5 mL), and dried in vacuo. Yield:
86 mg (93%). Anal. Found: C, 37.86; H, 3.63; N, 6.25.
C14H14O2N2Pt (437.3) requires: C, 38.45; H, 3.23; N, 6.41. IR, 1H
NMR, and 13C NMR spectra were found as reported in ref 8.
Synthesis of cis-[Pt(COMe)2(Hpz)2] (5). A mixture of complex
2 (140 mg, 0.498 mmol) and pyrazole (Hpz, 68 mg, 0.996 mmol)
was dissolved in cold (-70 °C) dichloromethane (5 mL) and
warmed to room temperature with stirring within 30 min. Afterward,
the volume of the reaction mixture was reduced in vacuo (2.5 mL),
and diethyl ether (10 mL) was added slowly. The resulting colorless
precipitate was filtered, washed with diethyl ether (10 mL), and
dried in vacuo. Yield: 135 mg (65%). Tdec: 141 °C. Anal. Found:
C, 27.72; H, 3.67; N, 13.66. C10H14N4O2Pt (417.32) requires: C,
28.78; H, 3.38; N, 13.43. 1H NMR (CDCl3, 200 MHz): δ 2.18 (s+d,
3JPt,H ) 23.0 Hz, 6H, COCH3), 6.12 (s, 2H, H4-Hpz), 7.11 (s, 2H,
3
δ 2.15 (s+d, JPt,H ) 25.5 Hz, 6H, COCH3), 7.24-7.32 (m, 4H,
3
3
H3-py), 7.72 (t, JH,H ) 7.7 Hz, 2H, H4-py), 8.61 (d, JH,H ) 4.9
Hz, 4H, H2-py). 13C NMR (125 MHz, CDCl3): δ 43.4 (s+d, JPt,C
2
) 378.2 Hz, COCH3), 125.2 (s, C3-py), 137.9 (s, C4-py), 151.2 (s,
C2-py), 228.5 (s+d, 1JPt,C ) 1268.4 Hz, COCH3). 195Pt NMR (107
MHz, CDCl3): δ -3376.5 (s). IR (CsBr): ν 3148 (m), 3048 (m),
1613 (s), 1590 (s), 1446 (m), 1410 (w), 1323 (w), 1111 (m), 1093
(m), 1063 (m), 1013 (w), 916 (w), 770 (m), 704 (m), 639 (w), 601
(w), 351 (w) cm-1
.
cis-[Pt(COMe)2(4-Mepy)2] (6b). A reaction in an NMR tube
analogous to the previous one using 4-methylpyridine (4-Mepy)
instead of pyridine afforded complex 6b in a mixture with excess
1
3
4-Mepy. H NMR (200 MHz, THF-d8) δ 1.92 (s+d, JPt,H ) 24.6
3
Hz, 6H, COCH3), 2.30 (s, 12H, pyCH3), 7.08 (d, JH,H ) 5.5 Hz,
4H, H3-py, free ligand), 7.17 (d, JH,H ) 6.0 Hz, 4H, H3-py), 8.38
3
(d, JH,H ) 5.6 Hz, 4H, H2-py, free ligand), 8.50 (d, JH,H ) 6.4
Hz, 1H, H2-py). 13C NMR (125 MHz, THF-d8): δ 20.8/20.9 (s,
pyCH3/pyCH3 free ligand), 44.8 (s+d, 2JPt,C ) 351.2 Hz, COCH3),
125.0 (s, C3-py, free ligand), 126.4 (s+d, 3JPt,C ) 17.3 Hz, C3-py),
147.1 (s, C4-py, free ligand), 150.4 (s, C2-py, free ligand), 151.8
3
3
(s+d, JPt,H ) 15.1 Hz, C2-py), 221.7 (s, COCH3).
2
Synthesis of cis-[Pt(COMe)2(NH2Bn)2] (7). At -70 °C ben-
zylamine (580 µL, 5.305 mmol) was added to complex 2 (150 mg,
0.534 mmol) in dichloromethane (4 mL) with stirring. The reaction
mixture was warmed to room temperature with stirring within 30
min, and the volume reduced in vacuo (1 mL). The resulting
colorless precipitate was filtered, washed with n-pentane (2 mL),
and dried in vacuo. Yield: 235 mg (89%). Tdec: 92-94 °C. Anal.
Found: C, 43.79; H, 4.99; N, 5.45. C18H24N2O2Pt (495.47) requires:
1
C, 43.63; H, 4.88; N, 5.65. H NMR (500 MHz, THF-d8): δ 2.10
3
(s+d, JPt,H ) 22.7 Hz, 6H, COCH3), 3.73-3.78 (m, 4H, CH2),
4.02 (s (br), 4H, NH2), 7.19-7.22 (m, 2H, p-CH), 7.28 (t, 3JH,H
)
7.6 Hz, 4H, m-CH), 7.43 (d, 3JH,H ) 7.5 Hz, 4H, o-CH). 13C NMR
(125 MHz, THF-d8): δ 43.8 (s, COCH3), 49.9 (s, CH2), 128.0 (s,
p-CH), 128.9 (s, o-CH), 129.2 (s, m-CH), 141.9 (s, i-C), 227.3 (s,
COCH3). IR (KBr): ν 3116 (w), 3026 (w), 1551 (s), 694 (m) cm-1
.

2492 Organometallics, Vol. 28, No. 8, 2009
Schwieger et al.
Synthesis of cis-[Pt(COMe)2(H2dmg)] (8). Dimethylglyoxime
(27 mg, 0.23 mmol) was added to a suspension of complex 2 (65
mg, 0.23 mmol) in dichloromethane and stirred for 10 h at room
temperature. The reaction mixture was filtered, and the solvent of
the red filtrate was removed in vacuo. The residue was recrystallized
from dichloromethane/diethyl ether. Yield: 60 mg (65%). Fp:
192-194 °C. Anal. Found: C, 24.34; H, 3.90; N, 6.96. C8H14N2O4Pt
(397.29) requires: C, 24.19; H, 3.55; N, 7.05. 1H NMR (200 MHz,
COCH3), 19.78 (s, 2H, OHO). 13C NMR (125 MHz, C6D6): δ 39.7
(s+d, 2JPt,C ) 169.9 Hz, COCH3), 229.6 (s+d, 1JPt,C ) 1453.5 Hz,
COCH3). 195Pt NMR (107 MHz, C6D6): δ -2817 (s). IR (CsBr): ν
2376 (w), 1547 (m), 1365 (s), 1299 (s), 1087 (m) cm-1
.
Synthesis of [Pt{(COMe)2H}(acac)] (11). A suspension of
complex 2 (200 mg, 0.712 mmol) in acetylacetone was stirred for
32 h at room temperature. The resulting dichroic green-violet
precipitate was filtered, washed with ethanol (5 mL) and diethyl
3
ether (5 mL), and dried in vacuo. Yield: 225 mg (83%). Tdec
:
CDCl3): δ 2.17 (s, 6H, NCCH3), 2.42 (s+d, JPt,H ) 25.3 Hz, 6H,
COCH3), 14.16 (s (br), 2H, NOH). 13C NMR (50 MHz, CDCl3):
129-132 °C. Anal. Found: C, 27.94; H, 3.93. C9H14O4Pt (381.28)
1
2
requires: C, 28.35; H, 3.70. H NMR (200 MHz, CDCl3): δ 2.08
12.9 (s, NCCH3), 43.0 (s+d, JPt,C ) 308.2 Hz, COCH3), 156.9
3
2
1
(s, 6H, CHCOCH3), 2.43 (s+d, JPt,H ) 13.5 Hz, 6H, PtCOCH3),
(s+d, JPt,C ) 30.2 Hz, CN), 236.8 (s+d, JPt,C ) 1323.5 Hz,
COCH3). 195Pt NMR (107 MHz, CDCl3): δ -3461 (s). IR (ATR):
ν 1817 (w), 1651 (w), 1624 (m), 1424 (m), 1363 (s), 1326 (s),
1130 (s), 1070 (m), 938 (m), 819 (m), 710 (m), 656 (m), 527 (w),
490 (m), 358 (m), 239 (m), 216 (m) cm-1. DTA (argon, 10 K/min):
T 190-210 (-30.74%), 210-720 (-20.75%) °C. UV/vis (solid):
5.60 (s, 1H, CH). 13C NMR (50 MHz, CDCl3): δ 24.9 (s,
CHCOCH3), 41.7 (s, PtCOCH3), 100.4 (s, CH), 191.1 (s,
CHCOCH3), 242.0 (s, PtCOCH3). Pt,C coupling constants could
not be observed due to low solubility of 11. 195Pt NMR (107 MHz,
CD2Cl2): δ -2729 (s). IR (ATR): ν 770 (w), 844 (w), 1027 (w),
1154 (m), 1201 (w), 1247 (w), 1268 (m), 1332 (m), 1359 (m), 1388
(m), 1532 (s), 1579 (s), 1618 (m), 1626 (m), 1680 (m), 2920 (w),
3143 (w) cm-1. DTA (argon, 5 K/min): T 100 (-5.47%), 110-400
(-54.05%) °C. UV/vis (solid): λmax 591 (s, br), 506 (sh), 327 (s),
284 (s), 222 (vs), 202 (sh) nm. UV/vis (in CH2Cl2): λmax (ꢀ/L mol-1
cm-1) 341 (1400), 307 (7500), 279 (6100), 234 (5800) nm.
Synthesis of [Pt{(COMe)2H}(hfacac)] (12). 1,1,1,5,5,5-Hexaflu-
oroacetylacetone (Hhfacac, 148 mg, 0.712 mmol) was added to a
suspension of complex 2 (100 mg, 0.356 mmol) in dichloromethane
(5 mL). After a reaction time of 72 h the volume of the reaction
mixture was reduced up to half in vacuo. The red precipitate was
filtered, washed with diethyl ether, and dried in vacuo. Yield: 89
mg (51%). Tdec: 114-116 °C. Anal. Found: C, 22.30; H, 1.97.
λmax 637 (m, br), 369 (s, br), 275 (sh), 230 (sh), 212 (vs) nm. UV/
vis (CH2Cl2): λmax 424 (w), 355 (sh), 321 (m), 262 (s) nm.
Synthesis of [Pt2(COMe)4(µ-pydz)2] (9). At -70 °C pyridazine
(36 mg, 0.448 mmol) was added to complex 2 (126 mg, 0.448
mmol) in dichloromethane (5 mL) by means of a syringe. Then
the reaction mixture was warmed to room temperature within 30
min and kept at this temperature for 15 min with stirring. The
resulting orange precipitate was filtered, washed with diethyl ether
(3 × 7 mL), and dried in vacuo. Yield: 27 mg (78%). Tdec: 100-102
°C. Anal. Found: C, 26.00; H, 3.47; N, 7.97. C16H20N4O4Pt2
(722.51) requires: C, 26.60; H, 2.79; N, 7.75. 1H NMR (200 MHz,
3
D2O): δ 2.32 (s+d, JPt,H ) 23.0 Hz, 12H, COCH3), 7.90 (m, 4H,
NCCH), 9.17 (m, 4H, NCH). 13C NMR (50 MHz, D2O): δ 43.6
1
2
C9H8F6O4Pt (489.23) requires: C, 22.10; H 1.65. H NMR (200
(s+d, JPt,C ) 337.0 Hz, COCH3), 133.5 (s, NC), 157.2 (s, NCC),
3
MHz, CDCl3): δ 2.50 (s+d, JPt,H ) 14.9 Hz, 6H, CH3), 6.40 (s,
1
235.0 (s+d, JPt,C ) 1296.0 Hz, COCH3). 195Pt NMR (107 MHz,
1H, CH). 19F NMR (188 MHz, CDCl3): δ -75.8 (s, CF3). 13C NMR
CDCl3): δ -3393 (s). IR (KBr): ν 3142 (w), 3082 (m), 3050 (m),
2977 (m), 2899 (w), 1617 (s), 1596 (s), 1573 (s), 1442 (w), 1413
(s), 1329 (m), 1292 (w), 1114 (s), 1094 (s), 1062 (w), 982 (w),
929 (w), 789 (w), 771 (w), 598 (w) cm-1. ESI-MS (positive mode,
MeOH): m/z 722.9 [M + H]+; m/z (obsd/calcd %) [M + Na]+:
741 (16/2), 742 (16/2), 743 (34/34), 744 (70/74), 745 (100/100),
746 (82/70), 747 (56/44), 748 (22/23). MS/MS (723): m/z 643, 585,
557, 541.
2
(125 MHz, C6D6): δ 34.3 (s+d, JPt,C ) 132.5 Hz, COCH3), 93.9
1
2
(m, CH), 117.9 (q, JF,C ) 284.8 Hz, CF3), 175.5 q, JF,C ) 35.3
Hz, COCF3), 229.6 (s+d, 1JPt,C ) 1487.7 Hz, COCH3). 195Pt NMR
(107 MHz, C6D6): δ -2764 (s). IR (ATR): ν 3152 (w), 1639 (m),
1617 (s), 1564 (s), 1453 (m), 1407 (w), 1347 (m), 1271 (s), 1203
(s), 1152 (s), 1101 (m), 815 (m), 685 (w) cm-1. UV/vis (solid):
λ
max 514 (s, br), 349 (sh), 303 (s), 223 (s) nm. UV/vis (in CH2Cl2):
λmax (ꢀ/L mol-1 cm-1) 323 (4500), 299 (5400), 264 (5600), 226
(6500) nm.
Synthesis of [Pt2{(COMe)2H}2(µ-Cl)2] (1) via Complex 2.
A. HCl (generated from NaCl and H2SO4) was bubbled over a
period of 30 min through a suspension of complex 2 (139 mg, 0.49
mmol) in nitromethane (10 mL) with stirring. Afterward, the yellow
reaction mixture was reduced in vacuo (2 mL), and after addition
of n-pentane (8 mL) complex 1 precipitated. It was filtered, washed
with n-pentane, and dried in vacuo. Yield: 66 mg (42%). B. To
complex 2 (139 mg, 0.49 mmol) in benzene (5 mL) first chlorot-
rimethylsilane (122 µL, 1.00 mmol) and then water (4.5 µL, 0.25
mmol) were added with stirring. After 2 h of stirring at room
temperature, the volume of the reaction mixture was reduced in
vacuo (1 mL). Then, the yellow precipitate was filtered and
recrystallized from dichloromethane (8 mL). Yield: 92 mg (60%).
Tdec: 183 °C. 195Pt NMR (CD2Cl2/C6D6, 107 MHz): δ -2756 (s)/
X-ray Crytal Structure Determinations. Suitable crystals for
X-ray diffraction analyses of complex 10, 11, and 12 have been
obtained from toluene solution at 5 °C (10), from recrystallization
with hot acetylacetone (11), and from recrystallization with hot
toluene (12). Intensity data were collected on STOE-IPDS and
Kappa-CCD (Bruker-Nonius) diffractometers using graphite-mono-
chromatized Mo KR radiation (λ ) 0.71073 Å) at 220(2) K (10)
and 100(2) K (11, 12), respectively. A summary of the crystal-
lographic data, the data collection parameters, and the refinement
parameters is given in Table 3. Absorption corrections were applied
semiempirically (10) and numerically (11, 12), respectively (Tmin.
/
Tmax.: 0.04/0.39, 10; 0.18/0.72, 11; 0.32/079, 12). The structures
were solved by direct methods with SHELXS-97 and refined using
full-matrix least-squares routines against F2 with SHELXL-97.22
All non-hydrogen atoms were refined with anisotropic displacement
parameters. Hydrogen atoms were refined isotropically, and their
positions were determined from the difference Fourier map in the
case of complex 11 or included in the models in calculated positions
using the riding model in the cases of complexes 10 and 12. As an
exception in structure 12, the position of H2 was taken from the
difference Fourier map and kept frozen during further refinement.
Complex 12 was found to crystallize in the space group P21/m with
the atoms Pt, O3, O4, and C1-C9 lying on the mirror plane. All
F and H atoms above and below this plane are therefore equally
1
-2717 (s). H and 13C NMR spectra were found as reported in
ref 6a.
Synthesis of [Pt2{(COMe)2H}2(µ-Br)2] (10). To complex 2 (171
mg, 0.61 mmol) in toluene (15 mL) first bromotrimethylsilane (160
µL, 1.21 mmol) and then water (7 µL, 0.39 mmol) were added
with stirring. After 2 h of stirring at room temperature, the reaction
mixture was filtered and the volume of the yellow filtrate was
reduced in vacuo (3 mL). At -40 °C complex 5 crystallized as
yellow needles, which were filtered at this temperature, washed
with n-pentane (2 mL), and dried in vacuo. Yield: 160 mg (72%).
Tdec: 94 °C. Anal. Found: C, 13.67; H, 2.17; Br, 22.39.
C8H14Br2O4Pt2 (724.16) requires: C, 13.27; H, 1.95; Br, 22.07. 1H
3
NMR (500 MHz, C6D6): δ 2.17 (s+d, JPt,H ) 21.8 Hz, 12H,
(22) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112–122.

Bis(acetyl)-Bridged Platinum(II) Coordination Polymer
Organometallics, Vol. 28, No. 8, 2009 2493
Table 3. Crystallographic and Data Collection Parameters for Complexes 10-12
10
11
12
empirical formula
Mr
C8H14Br2O4Pt2
724.19
C9H14O4Pt
381.29
C9H8F6O4Pt
489.24
cryst syst
space group
triclinic
P1
orthorhombic
Imma
monoclinic
P21/m
j
a/Å
b/Å
c/Å
4.5822(8)
8.930(2)
9.155(2)
73.43(2)
83.11(2)
75.47(2)
347.1(1)
1
16.725(3)
6.320(1)
9.620(2)
90
90
90
1016.8(3)
4
2.491
13.785
712
9.1107(6)
6.5655(2)
10.1263(7)
90
93.738(5)
90
604.43(6)
2
2.688
R/deg
ꢀ/deg
γ/deg
V/Å3
Z
Dcalc/g cm-1
3.464
25.881
320
µ(Mo KR)/mm-1
F(000)
11.696
452
θ range/deg
2.32-25.48
3.86-29.50
3.70-27.09
no. of reflns collected
no. of indep reflns
no. of reflns obsd [I > 2σ(I)]
no. of data/restraints/params
goodness-of-fit F2
R1/wR2 (I > 2σ(I))
R1/wR2 (∑)
3049
13 940
14 165
1199 (Rint ) 0.096)
1108
1199/0/74
1.195
0.0497/0.1426
0.0547/0.1610
3.33/-4.16
797 (Rint ) 0.070)
606
797/0/45
1.075
0.0169, 0.0378
0.0258, 0.0414
1.484/-1.409
1450 (Rint ) 0.0430)
1297
1450/18/148
1.051
0.0136/0.0264
0.0184/0.0276
0.450/-0.758
largest diff peak and hole/e Å-3
disordered over two positions. Atoms O1 and O2 have been found
to lie slightly out of the plane and are consequently also equally
disordered over two positions. It has been checked that the
refinement of the data in the space group P21 resulted in identical
disorders.
B3LYP.24 For the main group atoms the basis set 6-311++G(d,p)
was employed as implemented in the program. The valence shells
of platinum were approximated by split valence basis sets, too; for
their core orbitals effective core potentials in combination with
consideration of relativistic effects were used.25 All systems were
fully optimized without any symmetry restrictions. Except for
the open conformations (10*calc-12*calc), the resulting geometries
were characterized as equilibrium structures by analysis of the force
constants of the normal vibrations.
Crystallographic data for the structures reported in this paper
have been deposited at the Cambridge Crystallographic Data Center
(CCDC) as Supplementary Publication No. CCDC-716311 (10),
CCDC-716312 (11), and CCDC-716313 (12). Copies of the data
can be obtained free of charge on application to the CCDC, 12
Union Road, Cambridge, CB2 1EZ, U.K. (fax (internat.) +44-1223-
336033; e-mail deposit@ccdc.cam.ac.uk).
Acknowledgment. We gratefully acknowledge support by
the Deutsche Forschungsgemeinschaft. We also thank Merck
(Darmstadt, Germany) for gifts of chemicals.
Computational Details. All DFT calculations were carried out
with the Gaussian03 program package23 using the hybrid functional
Supporting Information Available: CIF files giving X-ray
crystallographic data of structures 10-12 and nuclear coordinates
as well as electronic energies of all calculated structures. This
material is available free of charge via the Internet at
http://pubs.acs.org.
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N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li,
X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.;
Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O. ; Austin, A. J. ;
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich,
S.; Daniels, A. D.; Strain, M. C.; Farkas, O. ; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B. ; Ortiz, J. V.; Cui, Q. ; Baboul, A. G.;
Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G. ; Liashenko, A. ;
Piskorz, P. ; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T. ; Al-Laham,
M. A. ; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.;
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