Phosphino-aminothiazoline platinum(II) and platinum(II)/gold(I) complexes: Structural, chemical and vapoluminescent properties

Article abstract of DOI:10.1002/chem.200701081

Phosphino-amino-thiazolines and -thiazoles can exist in solution in two tautomeric forms, in which the N-H proton involves the endo-cyclic or exo-cyclic nitrogen atom. The two tautomers show different reactivities toward alcoholysis; the imino form degrades more rapidly. Their bischelated platinum complexes were studied in the solid state by single crystal X-ray diffraction. Thus, the unique stereo electronic features of the [Pt(PN_th)] (PN_th = diphenylposphino-aminothiazoline) moiety were revealed. The complex cis-[Pt(PN_th)₂] reacts with gold(I) salts to yield dimetallic compounds, the molecular structures of which have been determined by X-ray diffraction. Solid cis-[Pt(PN_th)₂] shows vapoluminescent properties if exposed to alcohol vapors. A combined photophysical and crystallographic investigation has been carried out to clarify the unprecedented rigidochromic role of the alcohol in this phenomenon.

Full text of DOI:10.1002/chem.200701081

FULL PAPER
DOI: 10.1002/chem.200701081
Phosphino-Aminothiazoline Platinum(II) and Platinum(II)/Gold(I)
Complexes: Structural, Chemical and Vapoluminescent Properties
Roberto Pattacini,[a] Carlo Giansante,[b] Paola Ceroni,*[b] Mauro Maestri,[b] and
Pierre Braunstein*[a]
Dedicated to Prof. G. van Koten on the occasion of his 65th birthday
Abstract: Phosphino-amino-thiazolines
and -thiazoles can exist in solution in
two tautomeric forms, in which the
electronic features of the [Pt
(PNth =diphenylposphino-aminothiazo-
line) moiety were revealed. The com-
A
molecular structures of which have
been determined by X-ray diffraction.
Solid cis-[PtACHRTE(UGN PNth)2] shows vapolumi-
ꢀ
N H proton involves the endo-cyclic
plex cis-[Pt
salts to yield dimetallic compounds, the
G
nescent properties if exposed to alco-
hol vapors. A combined photophysical
and crystallographic investigation has
been carried out to clarify the unprece-
dented rigidochromic role of the alco-
hol in this phenomenon.
or exo-cyclic nitrogen atom. The two
tautomers show different reactivities
toward alcoholysis; the imino form de-
grades more rapidly. Their bischelated
platinum complexes were studied in
the solid state by single crystal X-ray
diffraction. Thus, the unique stereo-
Keywords: dimetallic complexes ·
luminescence
photochemistry
complexes · vapochromism
Introduction
of which follows a non-trivial reaction pathway involving
the intermediacy of the diphosphine Ph2PN=CN-
The reaction of PPh2Cl with primary amines in the presence
of NEt3 represents a simple and efficient synthetic method
for the preparation of a-aminophosphines.[1] The commer-
cial availability of a large number of functionalized amines
facilitates the fine tuningof the stereoelectronic properties
of this class of ligands. A systematic study of their coordina-
tion properties then becomes easier, as well as those of the
catalytic and physical properties of their metal complexes.[2]
We recently reported the synthesis of the new ligand
ACHTRE(UNG PPh2)CH2CH2S and phosphoryl migrations, as summarized
in Scheme 1.[3]
Ligand 1 readily leads to a stable bischelated platinum(II)
complex featuringits deprotonated form,
cis-[PtACHTREUNG(1ꢀH)2]
(Scheme 1). Access to this complex can result from ligand
deprotonation prior to chelation (Scheme 1), or from depro-
tonation of a dicationic bischelated complex, by takingad-
vantage of the enhanced acidity of the NH moiety upon
diphenylACHTREUNGphosphino-2-amino-2-thiazoline (1), the formation
[a] Dr. R. Pattacini, Dr. P. Braunstein
Laboratoire de Chimie de Coordination, Institut de Chimie
(UMR 7177 CNRS), UniversitØ Louis Pasteur, 4 rue Blaise Pascal
F-67070 StrasbourgCedex (France)
Fax : (+33)390-241-322
E-mail: braunstein@chimie.u-strasbg.fr
[b] C. Giansante, Prof. P. Ceroni, Prof. M. Maestri
Dipartimento di Chimica “G. Ciamician”, Università di Bologna
via Selmi 2, I-40126 Bologna (Italy)
Fax : (+39)051-2099-456
E-mail: paola.ceroni@unibo.it
Supportinginformation for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
Scheme 1.
Chem. Eur. J. 2007, 13, 10117 – 10128
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10117

P-coordination, which allows the use of bases weaker than
nBuLi, such as NEt3. Despite its remarkable stability, cis-
for ligands 2–5, suggesting that in these cases the more
nucleophilic exo-cyclic nitrogen is attacked first, yielding di-
A
ACHTREUNG
[Pt
G
rectly the desired monophosphine ligand.
Two tautomers of phosphines 1–5 are potentially present
in solution, as depicted in Scheme 2.
giving rise, for instance, to the formation of the heterodime-
tallic Pt/Agcoordination polymer [A{gPt
(Scheme 1, OTf=CF3SO3 ).[3]
We wished to investigate the coordination properties of
phosphino-thiazole and -thiazoline ligands, to study and
compare their solution behavior and the reactivity of their
transition metal complexes. Herein we report a comparative
study on a series of bischelated platinum(II) complexes,
which revealed that minor structural differences may result
in remarkably different chemical and photophysical proper-
ties.
Results and Discussion
Scheme 2.
Synthesis of the Ligands: Diphenylphosphino-aminothiazo-
line (1),[3] diphenylphosphino-aminothiazole (2),[4] and di-
phenylphosphino-aminobenzothiazole (3)[5] were prepared
Only the tautomeric form a has been reported in the liter-
ature for 2[6] and 3,[5] either in the solid state or in solution.
The concentration-dependent chemical shift of 47–51 ppm
for 1 suggested the presence in solution of both tautomers,
in rapid equilibrium and in a ꢁ1:1 molar ratio.[3] A conven-
ient NMR reference for imino tautomers b is provided by
accordingto the literature procedures, by reaction of PPh Cl
2
with the parent amine in the presence of NEt3. An analo-
gous approach was followed for diphenylphosphino-thiadia-
zole (4). Attempts to synthesize the diphenylphosphino-
methyl-aminobenzothiazole (5) followingthe strategy used
for 1–4 were unsuccessful, as Ph2P(O)PPh2 was formed in
ꢁ30% yield. This is due to the fact that amino-4-methyl-
benzothiazole competes with NEt3 as HCl scavenger, leav-
inga significant amount of PPh 2Cl unreacted, which in turn
is hydrolyzed to Ph2P(O)PPh2. This would imply that amino-
4-methyl-benzothiazole has a higher basicity than aminoben-
zothiazole. This may stem from the steric hindrance induced
by the methyl group, which prevents the formation of pseu-
dodimers of the type of those reported in Scheme 3 (see
below). Consequently, ligand 5 was prepared by reaction of
the parent amine with PPh2Cl in a 2:1 ratio, without the use
of an external base.
the diphosphine Ph2PN=CNACHTRE(UNG PPh2)CH2CH2S, whose exo-
cyclic, iminophosphine-type 31P nucleus resonates at 52 ppm,
in contrast to 42 ppm for the aminophosphine-type 31P
AHCTREUNG
nucleus.[3] The 31P chemical shift of 2, 3, and 5 is in the range
42.5–44.5 ppm, values which are typical for aminophos-
phines (i.e., 43 ppm for bis(diphenylphosphino)amine,
Ph2PNHPPh2). The NMR spectroscopy data for 3 were re-
corded in CDCl3 since, in contrast to a previous report,[5]
this phosphine is well soluble in chlorinated solvents and
shows a moderate solubility in toluene. The different behav-
ior of 1 compared to 2, 3, and 5 can be qualitatively ex-
plained by the ringheteroaromaticity of the latter, which de-
creases the basicity of the endo-cyclic nitrogen and thus, sta-
bilizes tautomer a. The 31P chemical shift of 4 at 51.7 ppm
indicates that tautomer b is the major species in solution,
rather surprisingly in view of the low basicity of the thiadia-
zole ring.
Ligands 1 and 4 rapidly undergo alcoholysis and react
with CH3OH to form the respective phosphinite and the
parent aminothiazoline. Since 2, 3, and 5 degrade more
slowly, the kinetics of this reaction appear to depend on the
availability in solution of tautomer b. The tautomers ob-
served in solution and the reactivity of 1–5 towards alcohol-
ysis are summarized in Table 1, together with the observed
31P NMR chemical shifts.
In comparison with 1–4, phosphine 5 is much more solu-
ble in organic solvents. The methyl group probably hinders
the formation of the pseudo-dimers typically observed in
the solid state (see for example, Scheme 3). Consistently the
NH NMR signal of 5 was not detected, even in concentrated
solutions of 5 in CDCl3, in contrast to those of 1–4, which
are in more rigid environments.
Despite the simplicity of the preparation procedure, a
study of the reaction mechanism leadingto 1 revealed the
involvement of an alternative pathway.[3] Phosphine 1 is in
fact the thermodynamic product of a multi-step reaction,
the diphosphine Ph2PN=CNACTHRE(UNG PPh2)CH2CH2S is initially
formed by the attack of PPh2Cl first on the endo-cyclic ni-
trogen of the amine, and then on the exo-cyclic one
(Scheme 1). Reaction of this diphosphine with the residual
amine, followed by phosphoryl group migration, finally
leads to the formation of 1. This pathway was not observed
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Platinum and Gold Luminescent Complexes
FULL PAPER
Table 1. Tautomers observed in solution for phosphines 1–5 and reactivi-
ty towards alcoholysis.
Ligand
Tautomer
observed
31P NMR
d [ppm]
Reactivity towards
alcoholysis [h][a]
1
2
3
4
5
a/b
a
a
b
a
47–52
42.3
44.5
51.7
43.0
ꢁ2
ꢁ48
ꢁ40
ꢁ2
ꢁ48
[a] 10:1 excess of MeOH in CDCl3, 100% conversion time.
Bischelated platinum(II) com-
plexes: Two equivalents of
aminophosphines 1–4 were re-
acted with [PtCl2A(NCPh)2] in
the presence of NEt3 to form
the complexes cis-[Pt(1ꢀH)2]
(cis-6), cis-[Pt(2ꢀH)2] (cis-7), cis-
[Pt(3ꢀH)2] (cis-8) and cis-[Pt-
(4ꢀH)2] (cis-9), respectively, in
almost quantitative yields.
AHCTREUNG
CTHREUNG
AHCTREUNG
Figure 1. View of the molecular structure of compound cis-6 in cis-
6·2CH3OH·CH3CN (Displacement parameters include 50% of the elec-
tron density).
AHCTREUNG
AHCTREUNG
AHCTREUNG
Scheme 3.
The poor solubility of these neutral, bischelated com-
plexes in MeCN facilitates their purification. Their X-ray
molecular structures are depicted in Figures 1–4 and select-
ed bond distances and angles are compared in Table 2. In
these complexes, two deprotonated ligands 1–4, respectively,
chelate the metal centre through the phosphorous and the
endo-cyclic nitrogen atoms. Although they display similar
geometrical parameters (Table 2), some structural details de-
serve comments.
Figure 2. View of the molecular structure of compound cis-7 (Displace-
ment parameters include 50% of the electron density).
While for cis-7–9 form b is more appropriate, on the basis
of structural parameters, resonance form a contributes sig-
nificantly to the bondingin cis-6, which should result in a
more nucleophilic character for the two exocyclic nitrogen
atoms and consequently, in their enhanced reactivity toward
electrophilic metal centers. We shall see below that this is
confirmed by the experimental observations.
Complex cis-6 co-crystallized with two molecules of
CH3OH and one of CH3CN. The CH3OH molecules form
hydrogen bonds with the exo-cyclic nitrogen atoms of the
complex to form CH3OH···cis-6···HOCH3 entities (O1···N1
and O2···N3 separations: 2.813(5) and 2.809(5) Š, respec-
tively) as illustrated in Figure 5.
In complex cis-6, the C=N double bond is more delocal-
ꢀ ꢀ
ized over the N C N unit than in cis-7–9, the distances are
ꢀ
ꢀ
ꢀ
similar (C1 N1 1.321(5) and C2 N2 1.327(5) Š; C16 N3
ꢀ
1.332(5) and C16 N4 1.317(5) Š). In contrast, the exo-cyclic
ꢀ
C1 N1 bond in cis-7–9 has more double bond character
ꢀ
ꢀ
than the endo-cyclic C1 N2 bond. The average S C3 and
N2 C2 distances are longer in cis-6 than in the other three
complexes, as a result of the non-aromaticity of the thiazole
ꢀ
ꢀ
ring. The value of the latter influences the bond order C1
N2. Two resonance forms can be formally envisaged for
complexes cis-6–9, see an example (cis-6) in Scheme 4.
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P. Braunstein, P. Ceroni et al.
Table 2. Selected bond distances [Š] for compounds cis-6–9, together
with a common atoms numberingscheme.
Scheme 4.
cis-6
cis-7
cis-8
cis-9
ꢀ
av. P Pt
2.238(1)
2.095(3)
1.663(3)
1.326(5)
1.322(5)
1.765(4)
1.799(4)
1.472(4)
2.2482(8)
2.106(2)
1.663(3)
1.315(4)
1.355(4)
1.751(3)
1.728(3)
1.382(4)
2.245(2)
2.121(4)
1.673(5)
1.316(7)
1.357(7)
1.752(6)
1.745(7)
1.410(7)
2.2525(8)
2.071(3)
1.668(2)
1.316(3)
1.356(3)
1.746(6)
ꢀ
av. N Pt
The acetonitrile methyl groups connect the CH3OH···cis-
6···HOCH3 moieties through H···O contacts, in such a way
that infinite chains of formula cis-6·2CH3OH·CH3CN are
formed. These chains are furthermore interconnected by
H···Pt contacts between 6 and the remainingmethyl hydro-
ꢀ
av. N P
ꢀ
av. C1 N1
ꢀ
av. C1 N2
C1 S
ꢀ
ꢀ
ꢀ
C3 S
N2 C2
1.742(7) (C1 S2)
1.381(8) (N2 N3)
ꢀ
ꢀ
gen of CH3CN (CCH ···Pt1 separation: 3.905(3) Š). The
3
intra-chain and inter-chain Pt···Pt separations are 9.8673(2)
and 16.0880(3) Š, respectively.
As far as the metal-ligand bond lengths are concerned, we
ꢀ
note that the Pt N bond distances increase in the sequence
cis-9<cis-6<cis-7<cis-8, probably as the result of the in-
creasingmutual repulsion of the groups in a-position to the
coordinatingnitrogen. This effect is maximized for complex
cis-8, in which the benzyl groups condensed to the thiazole
ringinduce
a helicoidal distortion around the metal
(Figure 6), as exemplified by the P1, P1’, N1’, N1 torsion
angle of 9.5(4)8.
In contrast to the situation in complexes cis-6–9, the
Pt-P1-N1-C1-N2 ringof cis-8 is not planar and adopts an
envelope conformation, the angle formed by the planes
passingthrough Pt1, P1, N1 and N1,C1,N2 being24.7(5) 8.
The 31P{1H} NMR spectra chemical shifts for cis-6–8 are at
ꢁ65 ppm with 1J(31P, 195Pt) couplingconstants ꢁ3350 Hz,
while a slight downfield shift is observed for cis-9, with a
resonance at 69.6 ppm.
Figure 3. View of the molecular structure of compound cis-8 in cis-
8·2CHCl3 (Displacement parameters include 50% of the electron densi-
ty). Symmetry operations generating equivalent atoms (’):ꢀx,ꢀy,z.
Although all these complexes were synthesized in almost
quantitative yields, an additional peak at 83.0 ppm in the
31P NMR spectrum of cis-9 was detected, in a ꢁ1:50 integra-
tion ratio with respect to the main peak, with 195Pt satellites
displayinga 1J(31P, 195Pt) couplingconstant of 2623 Hz. An
analysis of the crystal morphologies revealed the presence
of two distinct types of crystals. An X-ray diffraction analy-
sis of the less abundant one allowed its identification as
trans-PtCAHTRE(UGN 4ꢀH) (trans-9). An ORTEP view of its molecular
structure is shown in Figure 7.
In this centrosymmetric molecule, two deprotonated li-
gands 4 chelate the metal center in a trans arrangement of
the donor atoms. As a result of the mutual trans influence
ꢀ
of the phosphorus donors, the average P Pt distance is
longer in trans-9 (2.313(2) Š) than in cis-9 (2.252(1) Š),
ꢀ
while the N Pt bonds are shorter (2.011(5) Š for trans-9 vs.
2.071(3) Š for cis-9). The chelation angle remains almost
unchanged. The ligand displays bond distances and angles
similar to those observed in cis-9.
In the crystals of trans-9, the molecules are interconnected
by double H···N contacts (intermolecular C2···N3 distance:
3.39(1) Š), to form infinite chains that have Pt···Pt separa-
tions of 9.3273(3) Š (Figure 8).
Figure 4. View of the molecular structure of compound cis-9 (Displace-
ment parameters include 50% of the electron density).
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Platinum and Gold Luminescent Complexes
FULL PAPER
Figure 5. View of the crystal structure of cis-6·2CH3OH·CH3CN. Phenyl groups omitted for clarity. Symmetry operation generating equivalent molecules:
ꢀx,ꢀy,ꢀz; ꢀx,1/2+y, 1/2ꢀz.
Figure 6. Views of the molecular structure of complex cis-8 (phenyl
groups omitted for clarity). Pt: gray spheres.
Figure 8. View, along the c* axis of the crystal packingof compound
trans-9. Symmetry operation generating equivalent molecules: 1+x,y,z.
and 1ꢀx,y,z.
the non-coordinated thiadiazole nitrogen atom and the
phenyl protons may contribute to the stabilization the trans
arrangement.
Reactivity of the PtII metalloligands towards AuI complexes:
ꢀ
As indicated above, the C1 N2 bond of cis-6 is shorter than
in cis-7–9 and trans-9, which results in a larger contribution
of form a to the bonding(Scheme 4) and results in a higher
nucleophilicity of the nitrogen atom in the a position to
phosphorus. Reactions with electrophilic metal centers are
indeed faster with cis-6 than with complexes cis-7–9 and
trans-9.
Complexes cis-6–9 were reacted with [AuClACHTER(UNG tht)] (tht=
tetrahydrothiophene) in 1:1 and 1:2 ratios. Although coordi-
nation of AuCl fragments was observed for all the metallo-
AHCTRElUNG igands, the reactions with cis-7–9 resulted in unstable com-
Figure 7. View of the molecular structure of compound trans-9 (displace-
pounds which quickly decomposed with the formation of
gold mirrors. Only in the case of cis-6 we were able to iso-
ment parameters include 50% of the electron density). Selected bond
ꢀ
ꢀ
ꢀ
distances [Š] and angles [8]: N2 Pt1 2.011(5), P1 Pt1 2.3133(18), N1 P1
ꢀ
ꢀ
ꢀ
ꢀ
1.668(6), C1 N1 1.304(8), C1 N2 1.360(9), C2 N3 1.288(9), C1 S1
late stable compounds, namely [cis-6
ACHTRE(UNG AuCl)] (10) and [cis-6-
ꢀ
1.756(6), C2 S1 1.721(8), N2-Pt1-P1 79.35(16), N2-Pt1-P1 100.65(16).
Symmetry operation generating equivalent atoms (’): ꢀx,ꢀy,ꢀz.
AHCTREUNG
11·2CH2Cl2 are shown in Figure 9 and Figure 10, respective-
ly. Selected bond distances and angles are reported in
Table 3.
Both 10 and 11 are neutral dimetallic complexes. In 10
only one of the exo-cyclic nitrogen atoms of cis-6 is coordi-
nated to an AuCl group whereas in 11, each exo-cyclic N
atom is coordinated to an AuCl group as a 2e donor. Coor-
dination of the neutral AuI fragments to cis-6 leaves the geo-
metrical parameters of the latter almost unchanged, with
The PtII trans isomer has only been detected for ligand 4,
which is surprising, as the steric repulsion between the sub-
stituents in a position to the coordinated nitrogen atoms is
minimized in the trans vs. the cis isomer. Although cis-8 fea-
tures a pronounced repulsion between the benzo groups
condensed to the thiazole ring(see above), no trace of the
trans isomer could be detected. The steric repulsion between
the phenyl groups and the thiazole ring is minimized in
trans-9 as compared to the hypothetical trans-isomers of cis-
6–8. Moreover, multiple intramolecular contacts between
ꢀ
only a small change on the N C distances in the NCN
ꢀ
groups. In 10, the N1 C1 distance (1.346(7) Š) is only
ꢀ
ꢀ
slightly longer than N3 C16 (1.322(7) Š) and than N1 C1
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P. Braunstein, P. Ceroni et al.
ꢀ
(1.335(7) Š) and to N2 C1 in cis-6 (1.327(5) Š). A similar
trend is observed for complex 11.
The Pt/Au complexes 10 and 11 are stable and no degra-
dation was observed upon exposure to air or moisture for
days. Although 10 was obtained in good yields, traces of
compound 11 were always observed, even if [AuClACTHRE(UNG tht)] was
used in default. This implies that the addition of a second
equivalent of AuCl to cis-6 is only slightly slower than the
first. Compound 10 could be easily separated from 11 by
fractional crystallization. We noticed that when cycles of dis-
solution in common solvents followed by evaporation of the
solvent to dryness were applied to 10 and 11, the quantity of
complex dissolved gradually decreased, without appreciable
decomposition. Compounds 10 and 11 slowly, and almost
quantitatively, crystallize from their freshly prepared satu-
rated CHCl3 and CH2Cl2 solutions, respectively.
Although typical for terminal AuCl moieties, no close
Au···Au contacts are present in the crystal structures of 10
and 11 (minimum Au···Au separations: 6.3842(4) for 10 and
6.824(2) Š for 11). The chlorine atoms of 10 are in fact in-
volved in multiple H···Cl contacts, in particular with the sol-
vent and the thiazole protons (Figure 11). Pairs of molecules
Figure 9. View of the molecular structure of compound 10 in 10·3CHCl3
(Displacement parameters include 50% of the electron density).
Figure 11. View of the crystal structure of 10·3CHCl3, representinga pair
of complexes, interconnected by H···Cl contacts and interactingwith the
solvent through the AuCl moiety. Dashed lines represent H···Cl contacts.
White sticks represent the hydrogen atoms involved in these contacts.
Protons and phenyls omitted for clarity.
Figure 10. View of the molecular structure of compound 11 in
11·2CH2Cl2 (Displacement parameters include 50% of the electron den-
sity).
adopt a head to tail arrangement and are disposed parallel
to each other, forminglayers of complex molecules, which
are in turn separated by layers of solvent (Figure 12). Simi-
lar features are present in the crystal structure of 11. In this
case each CH2Cl2 molecule bridges two adjacent complexes
and interacts with the AuCl groups through H···Cl contacts
(Figure 13).
Examples of polynuclear compounds containing a-phos-
phino-amines and -imines bonded to two transition metal
centers with both phosphorus and a-N have been reported
Table 3. List of selected bond distances [Š] and angles [8] for compounds
10 in 10·3CHCl3 and 11 in 11·2CH2Cl2.
10
11
10
11
ꢀ
ꢀ
Au1 Cl1 2.254(2) 2.242(3)
N2 C1
1.305(7)
1.322(7)
1.335(7)
1.324(11)
1.346(10)
1.302(12)
178.4(2)
178.0(2)
80.9(2)
ꢀ
ꢀ
Au2 Cl2
–
2.249(2)
N3 C16
ꢀ
ꢀ
Au1 N1 2.032(4) 2.028(7)
N4 C16
ꢀ
Au2 N3
–
2.027(7)
Cl1-Au1-N1 179.2(2)
ꢀ
P1 N1
1.676(5) 1.680(7)
1.665(5) 1.689(7)
2.235(2) 2.236(2)
2.250(2) 2.233(2)
2.094(4) 2.093(7)
2.080(4) 2.115(7)
Cl2-Au2-N3
P1-Pt1-N2
P2-Pt1-N4
P1-N1-C1
P2-N3-C16
N1-C1-N2
–
ꢀ
P2 N3
80.6(2)
79.7(2)
114.2(4)
111.6(4)
124.2(5)
126.8(5)
ꢀ
P1 Pt1
81.3(2)
in the literature. They include complexes featuringmutually
[7]
ꢀ
P2 Pt1
115.3(6)
113.5(6)
122.1(8)
126.2(8)
interactingmetal centers,
deprotonated
dinuclear species bearing
ꢀ
N2 Pt1
Ph2PNHPPh2
(dppa)[8a–d]
or
ꢀ
N4 Pt1
Ph2PNHC6H4NHPPh2,[8e] phosphine functionalized macrocy-
cles bridging transition metals[9] and metal carbonyl clus-
ters.[10] At variance with their preparation, our strategy con-
sisted of the reaction of an isolated, mononuclear, difunc-
tional metalloligand, whose connectivity is fully maintained
ꢀ
N1 C1
1.346(7) 1.354(11) N3-C16-N4
ꢀ
in cis-6 (1.326(5) Š), while a shorteningof the N2 C1 dis-
ꢀ
tance is observed (1.305(7) Š) compared to N4 C16
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Platinum and Gold Luminescent Complexes
FULL PAPER
Figure 14. Photograph of an aluminum foil covered by a thin layer of the
dry complex cis-6 (ꢁ5 mgon a 12”5 cm surface) exposed to the radia-
tion of a common UV lamp for TLC analysis, at a wavelength of
ꢁ385 nm. The emission is restricted to areas in which the layer was treat-
ed with drops of CH3OH.
Figure 12. View of the crystal structure of 10·3CHCl3 alongaxis c, repre-
sentinglayers of parallel complex molecules separated by layers of sol-
vent. Molecules of 10 oriented in the same direction are depicted with
the same color.
Figure 15. Absorption spectrum of complex cis-6 in CH3OH solution at
298 K.
Figure 13. View of the crystal structure of 11·2CH2Cl2. Dashed lines rep-
resent H···Cl contacts. White sticks represent the hydrogen atoms in-
volved in these contacts. Protons and phenyls omitted for clarity.
equilibrated or in argon-saturated conditions, while in rigid
matrix at 77 K a strongluminescence occurs (Fiugre 16).
Slight changes in the band maximum, shape and excited-
state lifetimes (Table 4) and more pronounced differences in
the relative emission intensities were observed as a function
of solvent.
in the heterodimetallic product. This procedure has been
used previously,[11] for example, with [Pd
A
ACHTREU{NG Ph2PNPC-
ACHTREUNG
The nature of the emittingexcited state is not easy to as-
certain. A simplified classification based on a localized mo-
lecular orbital approach[12] (metal- or ligand-centered,
A
G
ACHTREUNG
Photophysical properties of the PtII complex cis-6: Complex
cis-6 is the only one in the series that, upon exposure of the
solid to CH3OH vapors, displays a luminescence visible to
the naked eye under excitation by usinga conventional UV
lamp
(Figure 14).
Moreover,
crystals
of
cis-
6·2CH3OH·CH3CN also displayed luminescence visible to
the naked eye, unlike those of cis-6·C6H5CH3.
This luminescent sensor property of cis-6 prompted us to
perform a detailed investigation of the photophysical prop-
erties of this complex, both in solution and in the solid state,
in the presence or not of alcohol vapors, and as a function
of temperature.
Photophysical properties of complex cis-6 in solution: Com-
plex cis-6 absorbs only in the UV region of the spectrum
with a maximum at 300 nm (Figure 15). At 298 K solutions
of cis-6 in alcohols (C2H5OH:CH3OH, 4:1 v/v) 2-methylte-
trahydrofuran, chlorinated solvents (CH2Cl2:CHCl3, 1:1 v/v)
or butyronitrile do not exhibit luminescence, either in air-
Figure 16. Emission spectra of complex cis-6 in rigid matrix at 77 K of
C2H5OH:CH3OH, 4:1 v/v (solid line), CH2Cl2:CHCl3, 1:1 v/v (dashed
line), butyronitrile (dotted line), and 2-methyl tetrahydrofuran (dashed-
dotted line). Emission intensities are directly comparable since these sol-
utions have the same absorbance at the excitation wavelength (lex
=
315 nm).
Chem. Eur. J. 2007, 13, 10117 – 10128
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10123

P. Braunstein, P. Ceroni et al.
Table 4. Photophysical properties of complex cis-6 in rigid matrix at
77 K. Relative intensities are directly comparable since the investigated
recorded at 120 K, but the emission intensity decreases and
complete loss of luminescence occurs above 160 K. In this
temperature range, butyronitrile becomes completely fluid
(Tf =161 K) and deactivation by non-radiative processes be-
comes faster.
solutions have the same absorbance at the excitation wavelength (lex
=
315 nm).
Matrix
lmax [nm]
Irel [a.u.]
t [ms]
C2H5OH:CH3OH, 4:1 v/v
CH2Cl2:CHCl3, 1:1 v/v
butyronitrile
510
525
510
495
100
90
75
25
15
20
20
Red-shifts of the emission bands, upon increasingtemper-
ature, have been reported for other complexes in which the
[14,15]
emittingexcited state has a charge transfer character.
2-methyl tetrahydrofuran
60
This phenomenon is a rigidochromic effect;[16] a large color
change of an emission as a function of the rigidity (visco-
AHCTREeUNG lasticity) of the medium. Matrix softeningmay remove vis-
metal-to-ligand or ligand-to-metal charge transfer) is not
satisfactory for this platinum(II) complex as states of mixed
nature are likely to exist.[13] The rather longlifetime and the
large energy difference between absorption and emission
bands suggest that this excited state is formally a triplet.
Free ligand 1 in a butyronitrile rigid matrix shows an un-
structured and very weak phosphorescence band with a
maximum at 440 nm, insensitive to solvent polarity and with
a longer lifetime (tꢁ5 ms) compared to complex cis-6. The
phosphorescence band maximum of complex cis-6 is red-
shifted compared to that of free ligand 1 and is quite sensi-
tive to solvent nature and temperature (vide infra), suggest-
ingthat the correspondingtransition is not merely ligand
centered, but has charge-transfer character.
cosity-dependent potential barriers presented by the solvent
cage, thus, enabling the complex to relax to lower energy
nuclear configurations corresponding to smaller equilibrium
distances between the metal centre and the ligands, not ac-
cessible in a rigid matrix.[15] Accordingto this model, de-
crease of lifetimes (t) can be accounted for by an additional
radiationless decay process of the emittingexcited state as
the temperature increases. In particular, values of t can be
fitted (solid line in Figure 17) according to the following em-
pirical formula [Eq. (1)]:[14]
1
k0 þ B
¼
ð1Þ
t
f1 þ exp½Cð1=Tꢀ1=TBފg
This describes a stepwise behavior centered at tempera-
As a result of the huge increase of luminescence intensity
for complex cis-6 upon loweringthe temperature from 298
to 77 K, we investigated in more detail the luminescence in-
tensity and excited-state lifetimes as a function of tempera-
ture. Figure 17 shows the changes in emission lifetime and
band maximum for butyronitrile solution (similar results
have been obtained in a CH2Cl2:CH3OH mixture) from 85
to 125 K. A strongdiscontinuity is present in the tempera-
ture range 100–120 K, in which the band maximum shifts
strongly to the red (from 495 to 550 nm), the luminescence
intensity decreases by a factor of ꢁ20 and the excited-state
lifetime slightly decreases (by about a third). At tempera-
tures above 125 K, no substantial change in the emission
band shape and position is observed in comparison to those
ture TB (k0 is a temperature-independent term, B is the
value attained by 1/t at T@TB and C is a temperature relat-
ed to the smoothness of the step). At low temperatures (85–
100 K in the present case), vibrational motions of the com-
plex occur much faster than reorientational and translational
rearrangements of the solvent molecules, so that the solvent
medium behaves as a rigid cage and some radiationless pro-
cesses, in particular the low-frequency ones, are inhibited.
The fittingof the data with this model in the temperature
range 85–125 K is good and leads to a value of TB =110 K.
Photophysics of complex cis-6 in the solid state: To better
understand the aforementioned effect of CH3OH on the lu-
minescence of complex cis-6, we have investigated the emis-
sion properties of a solid sample obtained by evaporation
from toluene solution before and after exposure to CH3OH
vapors at room temperature. In the presence of CH3OH a
much stronger luminescence[17] is observed (Figure 18) with
a maximum shifted to the blue (Table 5).
This vapoluminescence effect observed upon exposure to
CH3OH vapors of complex cis-6 crystallized from toluene,
cannot be attributed to a disruption of intermolecular Pt···Pt
interactions, as in the case of previously reported PtII com-
plexes.[18] Indeed, the single crystal X-ray diffraction analysis
of complex cis-6 crystallized from toluene, cis-6·C6H5CH3,
revealed a molecular structure almost identical to that
found in cis-6·2CH3OH·CH3CN, with a shorter minimum
Pt···Pt intermolecular distance: 5.9267(2) Š for cis-
6·C6H5CH3 and 8.9268(2) Š for cis-6·2CH3OH·CH3CN. The
crystal data for cis-6·C6H5CH3 are reported in the CIF file
deposited in the CCDC database (CCDC code: 653227). In
Figure 17. Emission lifetime (solid circles, right axis) and emission band
maximum (empty squares, left axis) as a function of temperature for
complex cis-6 in butyronitrile. lex =315 nm. The solid line represents the
fitted curve accordingto Equation (1).
10124
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Chem. Eur. J. 2007, 13, 10117 – 10128

Platinum and Gold Luminescent Complexes
FULL PAPER
A vapoluminescent effect was also observed upon expo-
sure of solid cis-6 to CH3CH2OH (Figure 18), but the in-
crease in the luminescence intensity is lower and the band
maximum is more shifted to the red (Table 5).
(CH3)2CHOH has a very modest effect (Figure 18), a slight
increase in emission intensity and small red-shift of the band
maximum (Table 5), whereas CH3ACHTRE(UGN CH2)3OH does not lead
to any significant increase in luminescence or change in the
emission band maximum. Luminescence intensity decays of
these solid samples are multiexponential and they can be
fitted by usingtwo families of lifetimes ( t1 ꢁ0.2 ms, t2
ꢁ1.0 ms) in which the percentage of the longer lifetime in-
creases upon increasingemission quantum yield.
Figure 18. Emission spectra of complex cis-6 crystallized from toluene
(dashed line) or exposed to CH3OH (solid line), CH3CH2OH (dashed-
The solid samples discussed above show a much stronger
luminescence at 77 K, a lifetime of 20 ms, and a significantly
blue-shifted emission maximum compared to the corre-
spondingvalues at room temperature (Table 5), confirming
the charge transfer character of the corresponding electronic
transition. The emission bands recorded under these experi-
mental conditions are very similar in shape and position to
those recorded in the correspondingrigid matrix. Therefore,
the emission in the solid state is of the same nature as that
observed for diluted solutions (ꢁ5”10ꢀ5 m) at 77 K, and is a
property of the isolated molecule, thus confirmingthat
Pt···Pt interactions do not play any role in the luminescence
properties of these solid samples.
dotted line), or (CH3)2CHOH (dotted line) at room temperature. lex
=
313 nm.[17]
Table 5. Photophysical properties of complex cis-6 at 298 and 77 K for
solid samples exposed to different alcohol vapors. lex =315 nm.
298 K
lmax [nm]
77 K
lmax [nm]
Vapor
t [ms]
t [ms]
[a]
530
520
550
540
0.2, 1.0
0.2, 1.0
0.2, 1.0
0.2, 1.0
520
505
540
530
20
20
20
20
CH3OH
CH3CH2OH
ACHTREUNG(CH3)2CHOH
[a] Crystals obtained by toluene solutions without exposure to any alco-
hol vapor.
Conclusion
the solid state structure of cis-6·2CH3OH·CH3CN, a CH3OH
molecule forms a hydrogen bond with each exo-cyclic nitro-
gen atoms of the complex (Figure 5 and Scheme 5).
By analogy with complexes containing a coordinated P,O-
phosphanyl enolate ligand,[2a] which react with softer elec-
trophiles such as transition metal centers at the enolate
carbon a to P, we have provided here further examples
showingthat complexes containingan isoelectronic P,N-
phosphanyl iminolate chelate can also lead to heterodime-
tallic complexes in a controlled way. With the latter systems,
ꢀ
the advantage is that the coordination geometry of the P N
nitrogen atom remains planar upon metalation, which sim-
Scheme 5.
plifies the stereochemical issues one encounters with the
ꢀ
correspondingP
C
system since upon metalation, the
carbon atom becomes a sp3-hybridized stereogenic center.[21]
We have found that rather minor stereoelectronic differ-
ences in the ligands may significantly affect the chemical
and physical properties of the related complexes. The vapo-
luminescence properties of cis-6 prompts us to study the co-
ordination properties of ligand 1 toward less precious
metals, to fine tune their potential activity as sensors. The
rationalization of the unprecedented H-bondingrigidochro-
mic effect of the alcohol will allow us to better tune these
structural and physical properties.
Because of the structural effect of the N···HOCH3 hydro-
gen bonding, complex cis-6·2CH3OH·CH3CN has a more
rigid structure then cis-6·C6H5CH3. This may explain the in-
crease of emission quantum yield, because deactivation by
non-radiative decays is slower in a more rigid structure. Re-
markable electronic effects of this hydrogen bonding on cis-
6 and therefore on the luminescence properties are unlikely.
The NMR spectroscopic data of cis-6 in CH3OH solutions
are in fact very similar to those in CDCl3 and the molecular
structures of cis-6 in cis-6·2CH3OH·CH3CN and in cis-
6·C6H5CH3 are almost identical. In the crystals of cis-
6·2CH3OH·CH3CN molecules of acetonitrile were also pres-
ent. On the other hand, acetonitrile vapors did not lead to
luminescent properties for dry cis-6.
Experimental Section
General Considerations: All manipulations were carried out under inert
dinitrogen atmosphere, using standard Schlenk-line techniques and dried
Chem. Eur. J. 2007, 13, 10117 – 10128
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10125

P. Braunstein, P. Ceroni et al.
and freshly distilled solvents. The 1H, 13C{1H}, and 31P{1H} NMR spectra
were recorded at 298 K by usinga Bruker Avance 300 instrument at
300.13, 75.47 and 121.49 MHz, respectively, usingTMS or H 3PO4 (85%
in D2O) as external standards with downfield shifts reported as positive.
All NMR spectra were measured at 298 K. The assignment of the signals
was made by 1H, 1H-COSY and 1H,13C-HMBC experiments. Elemental
C, H, and N analyses were performed by the “Service de microanalyses”,
UniversitØ Louis Pasteur, Strasbourg. The following compounds were
calcd (%) for C30H24N4P2PtS2 (761.70): C 47.31, H 3.18, N 7.36; found: C
47.26, H 3.41, N 7.20.
Preparation of complexes cis-6, cis-8 and cis-9: The procedure described
for complex cis-7 was also applied to the synthesis of cis-6, cis-8 and cis-
9, by using0.363, 0.423 and 0.362 gof phosphines 1, 3 and 4, respectively,
instead of 2. Yields: 0.463 g, 96% for cis-6; 0.483 g, 89% for cis-8;
0.361 g, 75% for cis-9.
Complex cis-6 was recrystallized from a 2:2:1 CH2Cl2/CH3OH/CH3CN
solution, giving cis-6·2CH3OH·CH3CN. Complexes cis-8 and cis-9 were
recrystallized by layeringpentane on their saturated CH 2Cl2 solutions.
The spectroscopic data for cis-6 have been reported elsewhere.[3]
prepared accordingto literature procedures: [PtCl
(tht)],[20] 1,[3] and 2.[4] PPh2Cl and NEt3 were freshly distilled before use.
(NCPh)2],[19] [AuCl-
2ACHTREUNG
ACHTREUNG
Other chemicals were commercially available and used as received.
Spectroscopic data for cis-8: 1H NMR (CDCl3): d=6.71 (m, 2H; H6),
6.80–6.91 (m, 4H; H7, H5), 7.00–7.38 (m, 14H; m,p-Ph and H4),
7.53 ppm (m, 8H; o-Ph); C{1H} NMR (CDCl3): d=117.8 (s; C7), 121.1
(s; C4), 121.2 (s; C5), 124.9 (s; C6), 128.1–133.2 (m; Ph), 129.9 (s, 4J-
ꢀ
Preparation of ligand 3: Ligand 3 was prepared usinga method similar to
that already reported.[5] In contrast to the literature data, a high solubility
in chlorinated solvents was observed. The NMR data recorded in CDCl3
are listed below. 1H NMR (CDCl3, the labelingof the atoms refers to
that of the ligand in the ORTEP plot of cis-8 (Figure 3): d=6.85 (m, 1H;
H7), 7.25–7.40 (m, 6H; m,p-Ph), 7.07 (m, 2H; H5, H6), 7.43 (m, 4H; o-
Ph), 7.59 (m, 1H; H4), 8.81 ppm (s br, 1H; NH); 13C{1H} NMR (CDCl3):
d=119.2 (s; C7), 120.9 (s; C4), 122.3 (s; C5), 125.8 (s; C6), 128.7 (d,
AHCTREUNG
(C,P)=13.8 Hz; C3), 147.8 (s; C2), 187.2 ppm (s; N C=N); 31P{1H} NMR
1
(CDCl3): d=69.1 ppm (s, with 195Pt satellites, J
ACHTRE(UNG P,Pt)=3368 Hz); elemen-
tal analysis calcd (%) for C38H28N4P2PtS2 (861.81): C 52.96, H 3.27, N
6.50; found: C 52.87, H 3.24 N 6.73;
3J
131.4 (d, 2J
(s; C2), 171.2 ppm (d, JACHTREUNG
A
ACHTRE(UNG C,P)=13.8 Hz; C3),
1
Spectroscopic data for cis-9: H NMR (CDCl3): d=7.05–7.15 (m, 8H; m-
A
ACHTREUNG
Ph), 7.24–7.37 (m, 12H; o,p-Ph), 8.26 ppm (filled-in d with Pt satellites,
2
5
2
simulated J
(CDCl3): d=128.1–132.6 (m; Ph), 139.8 (m, 4J
(P,P)=12.2 Hz, value extracted from the phenyl carbon pattern m; N=
(P,P)=12.2 Hz, 2H; N=CH); 13C{1H} NMR
ACHRTUNEG(H,P)=4.0 Hz, JACHTREUGN
AHCTREUNG
(C,P)=6.5 Hz with 2J-
rated solution) d=44.5 ppm (s); elemental analysis calcd (%) for
C19H15N2PS (334.38): C 68.25, H 4.52, N 8.38; found: C 68.37, H 4.74, N
8.61.
AHCTREUNG
CH), 188.4 ppm (s; N C=N); 31P{1H} NMR (CDCl3): d=69.6 ppm (s,
ꢀ
with Pt satellites; 1J
AHCTREUNG
Preparation of ligand 4: Liquid Ph2PCl (1.82 mL, 9.9 mmol) was added
dropwise to a solution of amino-thiadiazole (2.00 g, 19.8 mmol) in THF
(100 mL). The solution was stirred for 6 h, amino-thiadiazolonium chlo-
ride was removed by filtration, the volatiles were removed under reduced
pressure and the colorless solid obtained was dissolved in a minimum
amount of THF. Pentane was slowly layered onto the THF solution yield-
ing 4 as colorless crystals, which were then washed with Et2O (2”50 mL).
Yield: 2.35 g, 83%. 1H NMR (CDCl3): d=7.33–7.43 (m, 6H; m,p-Ph),
C28H22N6P2PtS2 (763.67): C 44.04, H 2.90, N 11.00; found: C 44.39, H
2.90, N 10.84.
Preparation of complex 10:
A solution of [AuClACHRTE(UNG tht)] (0.200 g,
0.62 mmol) in CH2Cl2 (10 mL) was added dropwise, over a period of
10 min, to a solution of cis-6 (0.474 g, 0.62 mmol) in CH2Cl2 (50 mL).
After the solution was stirred for 20 min, the volatiles were removed
under vacuum. The colorless solid obtained was washed with Et2O (3”
20 mL) and then redissolved in a minimum amount of CH2Cl2. After 2
7.46–7.57 (m, 4H; o-Ph), 8.43 ppm (d, 5J
13C{1H} NMR (CDCl3): d=128.8 (d, 3J
(C,P)=7.3 Hz; m-Ph), 130.0 (s; p-
Ph), 131.4 (d, 2J(C,P)=21.0 Hz; o-Ph), 137.6 (d, 1J
(C,P)=8.2 Hz; i-Ph),
143.9 (d, 4J(C,P)=6.4 Hz; N=CH), 172.4 ppm (d, 2J
ACHTRE(UNG H,P)=2.3 Hz, 1H; N=CH);
1
days 10·2CH2Cl2 crystallized. Yield: 0.402 g, 65%. H NMR (CDCl3): d=
AHCTREUNG
3.58 (m, 3J
A
ACHTRE(UNG H,H)=7.12 Hz, 2H;
A
ACHTREUNG
H17), 4.32 (t, 3J
ACHTRE(UNG H,H)=7.12 Hz, 2H; H2), 7.0–7.50 ppm (m, 20H; Ph);
ꢀ
A
ACHTRE(UNG C,P)=28.3 Hz; N
31P{1H} NMR (CDCl3): d=64.4 (d, 2J
(P,P)=11.7 Hz, with 195Pt satellites,
C=N); 31P{1H} NMR (CDCl3): d=51.7 ppm (s); elemental analysis calcd
(%) for C14N3H12PS (285.30): C 58.94, H 4.24, N 14.73; found: C 59.18, H
4.15, N 14.39.
1J
1J
C
(P,P)=11.7 Hz, with 195Pt satellites,
2
Preparation of ligand 5: Liquid Ph2PCl (1.121 mL, 6.1 mmol) was added
dropwise to
a solution of 2-amino-4-methyl-benzothiazole (2.00 g,
12.2 mmol) in THF (100 mL). After the solution was stirred for 6 h, 2-
amino-4-methyl-benzothiazolonium hydrochloride was removed by filtra-
tion. Evaporation of the volatiles yielded compound 5 as a colorless
powder. Yield: 1.91 g, 90%. 1H NMR (CDCl3, The labelingof the atoms
refers to that of ligand 3): d=2.51 (m, 3H; CH3), 7.02–7.13 (m, 2H; H5,
H6), 7.30–7.60 ppm (m, 11H; Ph, H4); 13C{1H} NMR (CDCl3): d=18.4
Preparation of complex 11:
A solution of [AuClACHRTE(UNG tht)] (0.200 g,
0.62 mmol) in CH2Cl2 (10 mL) was added dropwise, over a period of
10 min, to a solution of cis-6 (0.237 g, 0.31 mmol) in CH2Cl2 (30 mL).
After the solution was stirred for 20 min, the volatiles were removed
under vacuum. The colorless solid obtained was washed with Et2O (3”
20 mL) and then redissolved in a minimum amount of CHCl3. After 2
days 11·3CHCl3 crystallized Yield: 0.331 g, 87%. 31P{1H} NMR (CDCl3):
(s; CH3), 118.6 (s; C4), 122.5 (s; C5), 126.9 (s; C6), 128.8 (d, 3J
7.0 Hz; m-Ph), 129.2 (s; C7), 129.9 (s; p-Ph), 131.4 (d, 2J
(C,P)=20.7 Hz;
o-Ph), 131.6 (d, 2J(C,P)=12.2 Hz; C3), 137.6 (d, 1J
(C,P)=8.5 Hz; i-Ph),
150.5 (s; C2), 168.8 ppm (d, J
ACHTRE(UNG C,P)=
AHCTREUNG
d=73.8 ppm (s, with 195Pt satellites, 1J
(CDCl3): d=3.58 (t, 3J(H,H)=7.4 Hz, 4H; SCH2), 4.50 (t, 3J
ACHTREUNG
ACHTREUNG
A
ACHTREUNG
A
2
AHCTREUNG
(C,P)=33.0 Hz; N C=N); 31P{1H} (CDCl3):
ꢀ
7.4 Hz, 4H; NCH2), 7.0–7.5 ppm (m, 20H; Ph); the poor solubility of this
complex prevented recordingof good quality 31C{1H} NMR spectra; ele-
mental analysis calcd (%) for C30H28N4Au2Cl2P2PtS2 (1230.6): C 29.28, H
2.29, N 4.55; found: C 28.78, H 2.22, N 4.36.
d=43.0 ppm (s); elemental analysis calcd (%) for C20H17N2PS (348.4): C
68.95, H 4.92, N 8.04; found: C 68.92, H 5.00, N 7.94.
Preparation of complex cis-7: To a stirred solution of [PtCl2ACHTREU(NG NCPh)2]
(0.300 g, 0.63 mmol) in THF (100 mL), were added NEt3 (0.500 mL,
3.59 mmol) and solid 2 (0.360 g, 1.27 mmol). Stirring was continued for
1 h and Et3NH·Cl was removed by filtration. The volatiles were removed
under reduced pressure and the colorless powder obtained was washed
with amounts of MeCN (5”10 mL). Evaporation of the volatiles gave
pure compound 7 as a colorless powder. Yield: 0.446 g, 93%. 1H NMR
X-ray data collection, structure solution and refinement for compounds
cis-6·2CH3OH·CH3CN, cis-7, cis-8·2CHCl3, cis-9, trans-9, 10·3CHCl3
and 11·2CH2Cl2: Suitable crystals for the X-ray analysis were obtained as
described above. The intensity data was collected at 173(2) K on a Kappa
CCD diffractometer[22] (graphite monochromated MoKa radiation, l=
0.71073 Š). Crystallographic and experimental details for the structures
are summarized in Table 6. The structures were solved by direct methods
(SHELXS-97) and refined by full-matrix least-squares procedures (based
on F2, SHELXL-97)[23] with anisotropic thermal parameters for all the
non-hydrogen atoms. The hydrogen atoms were introduced into the geo-
metrically calculated positions (SHELXS-97 procedures) and refined
(CDCl3, for atom labeling, see ORTEP plot) d=6.27 (ddd, 3J
4.5 Hz, 5J
(H,P)=2.7 Hz, 1.9 Hz, 2H; SCH), 7.03–7.10 (m, 8H; m-Ph),
7.16 (dd, 3J
ACHTRE(UNG H,H)=
ACHTREUNG
ACHTREUNG AHCTRE(UGN H,P)=0.9 Hz, 2H; NCH), 7.23–7.37 ppm
(H,H)=4.5 Hz, 4+5J
(m, 12H; o,p-Ph); 13C{1H} NMR (CDCl3): d=104.3 (s; C2, C17), 127.9–
133.2 (m; Ph), 133.6 (s; C3, C18), 189.8 ppm (s; N-C=N);
31P{1H} (CDCl3) d=66.0 ppm (s, 1J
(P,Pt)=3310 Hz); elemental analysis
ridingon the correspondingparent atoms. CCDC-653221
(
cis-
10126
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Chem. Eur. J. 2007, 13, 10117 – 10128

Platinum and Gold Luminescent Complexes
FULL PAPER
Table 6. X-ray data collection and refinement parameters for compounds cis-6·2CH3OH·CH3CN, cis-7, cis-8·2CHCl3, cis-9, trans-9, 10·3CHCl3 and
11·2CH2Cl2.
cis-6
cis-7
cis-8·
cis-9
trans-9
10
11
·2CH3OH·CH3CN
2CHCl3
·3CHCl3
·2CH2Cl2
formula
C30H28N4P2PtS2
·CH3CN·2CH3OH
870.85
monoclinic
P21/c
12.5240(1)
16.0880(2)
18.2060(3)
90
109.664(1)
90
C30H24N4P2PtS2 C38H28N4P2PtS2 C28H22N6P2PtS2 C28H22N6P2PtS2 C30H28AuClN4P2PtS2 C30H28Au2Cl2N4P2PtS2
·2CHCl3
1100.53
monoclinic
C2/c
·3CHCl3
1356.23
triclinic
·2CH2Cl2
1400.40
triclinic
FW
761.68
monoclinic
P21/c
763.67
763.67
monoclinic
P21/c
crystal system
space group
a [Š]
b [Š]
c [Š]
triclinic
¯
¯
¯
P1
P1
P1
14.8660(2)
11.8280(2)
16.2700(2)
90
100.830(5)
90
24.7820(9)
12.0870(4)
14.8360(7)
90
105.786(2)
90
11.3530(1)
13.9230(2)
18.7650(3)
100.315(1)
91.037(1)
109.245(1)
2745.62(6)
4
9.3273(3)
10.2960(6)
16.763(1)
90
120.569(3)
90
11.7520(4)
12.6110(6)
15.2310(7)
84.644(2)
80.594(2)
88.458(4)
2217.0(2)
2
9.175(5)
12.305(5)
18.689(5)
103.517(5)
98.950(5)
99.066(5)
1984(1)
2
a [8]
b [8]
g [8]
V [Š3]
Z
3454.33(8)
4
1.675
2809.37(7)
4
4276.4(3)
4
1386.1(1)
2
1calcd [gcmꢀ3
]
1.801
1.709
1.847
1.830
2.032
2.343
F
(000)
1736
1488
2160
1488
744
1292
1304
crystal size
[mm]
0.1”0.1”0.1
0.13”0.10”0.08 0.13”0.11”0.10 0.11”0.09”0.09 0.12”0.10”0.10 0.15”0.14”0.11
0.08”0.07”0.07
m [mmꢀ1
]
4.32
5.29
3.86
5.41
5.36
7.26
11.51
15603
9094
rflns. collected 19237
rflns. unique
rflns. obs.
33113
8221
7046
7871
4707
3103
22486
15989
13309
14475
4044
2539
17552
10693
7974
10080
6438
6679
ACHTREUNG[I>2s(I)]
parameters
R indices
[I>2s(I)]
426
R1 =0.040
wR2 =0.085
352
R1 =0.028
wR2 =0.060
361
R1 =0.052
wR2 =0.106
719
R1 =0.029
wR2 =0.058
178
R1 =0.048
wR2 =0.100
478
R1 =0.041
wR2 =0.092
463
R1 =0.045
wR2 =0.110
6·2CH3OH·CH3CN), CCDC-653222 (cis-7), CCDC-653223 (cis-
8·2CHCl3), CCDC-653224 (cis-9), CCDC-653225 (10·3CHCl3), CCDC-
653226 (11·2CH2Cl2), CCDC-653228 (trans-9) contain the supplementary
crystallographic data for this paper that can be obtained free of charge
from the Cambridge Crystallographic Data Centre via www.ccdc.cam.
ac.uk/data_request/cif.
to Dr. A. DeCian (ULP Strasbourg) for the crystal structure data collec-
tion, and to Prof. R. Welter (ULP Strasbourg) for the refinement of the
crystal structure of compound 7.
[1] Z. Fei, P. J. Dyson, Coord. Chem. Rev. 2005, 249, 2056–2074.
[2] See for example, a) P. Braunstein, Chem. Rev. 2006, 106, 134–159;
b) P. Braunstein, F. Naud, Angew. Chem. 2001, 113, 702–722;
Angew. Chem. Int. Ed. 2001, 40, 680–699; c) G. Helmchen, A.
Pfaltz, Acc. Chem. Res. 2000, 33, 336–345; d) C. S. Slone, D. A.
Weinberger, C. A. Mirkin, Prog. Inorg. Chem. 1999, 48, 233–350.
[3] G. Margraf, R. Pattacini, A. Messaoudi, P. Braunstein, Chem.
Commun. 2006, 3098–3100.
[4] H. L. Milton, M. V. Wheatley, A. M. Z. Slawin, J. D. Woollins, Inorg.
Chim. Acta 2005, 358, 1393–1400.
[5] Z. Garcia-Hernandez, A. Flores-Parra, J. M. Grevy, A. Ramos-Or-
ganillo, R. Contreras, Polyhedron 2006, 25, 1662–1672.
[6] O. Kühl, B. Walfort, T. Rüffer, Cryst. Growth Des. 2006, 6, 366–368.
[7] a) H. Nagashima, T. Sue, T. Oda, A. Kanemitsu, T. Matsumoto, Y.
Motoyama, Y. Sunada, Organometallics 2006, 25, 1987–1994; b) Y.
Sunada, T. Sue, T. Matsumoto, H. Nagashima, J. Organomet. Chem.
2006, 691, 3176–3182; c) D. Fenske, B. Maczek, K. Maczek, Z.
Anorg. Allg. Chem. 1997, 623, 1113–1120; d) A. M. Baranger, R. G.
Bergman, J. Am. Chem. Soc. 1994, 116, 3822–3835.
[8] a) R. Uson, A. Laguna, M. Concepcion Gimeno, J. Chem. Soc.
Dalton Trans. 1989, 1883–1886; b) R. Uson, A. Laguna, M. Laguna,
M. C. Gimeno, P. G. Jones, C. Fittschen, G. M. Sheldrick, J. Chem.
Soc., Chem. Commun. 1986, 509–510; c) J. Ellermann, W. Wend,
Nouv. J. Chim. 1986, 10, 313–320; d) M. Knorr, unpublished results.
e) P. A. Bella, O. Crespo, E. J. Fernandez, A. K. Fischer, P. G. Jones,
A. Laguna, J. M. Lopez-de-Luzuriaga, M. Monge, J. Chem. Soc.
Dalton Trans. 1999, 4009–4017.
Photophysical experiments: All the experiments were carried out using
spectrophotometric-grade solvents purchased from Merck, by using
either air-equilibrated or argon-purged solutions. The solvents have been
chosen to give a transparent matrix at 77 K. UV-Vis absorption spectra
were recorded with a Perkin–Elmer l40 spectrophotometer, usingquartz
cells with a pathlength of 1.0 cm. Fluorescence spectra were performed
with a Perkin–Elmer LS-50 or an Edinburgh FLS920 spectrofluorimeter,
equipped with a Hamamatsu R928 phototube. Fluorescence lifetimes
were measured by the above mentioned Edinburgh FLS920 spectro-
fluoremeter equipped with a TCC900 card for data acquisition in time-
correlated single-photon counting experiments (0.5 ns time resolution)
with a D2 lamp. Measurements of emission spectra and lifetimes as a
function of temperature were performed by insertinga quartz cell in a
cryostat equipped with a temperature controller (model TC1) by Oxford
Instruments. The estimated experimental errors are: ꢂ2 nm on the band
maximum, 5% on the molar absorption coefficient, 5% on the fluores-
cence lifetime, 20% on the emission quantum yields. For solid samples,
we made comparisons of emission quantum yields in the text; although
the experimental error is rather large, we tried to minimized it by averag-
ingmultiple spectra without movingthe sample for measurements in the
presence or absence of vapors.
Acknowledgements
This work was supported by the Centre National de la Recherche Scienti-
fique, the Minist›re de l’Enseignement SupØrieur et de la Recherche and
the ANR (no. 06-BLAN-0410-01) in France and by MIUR (PRIN, “Siste-
mi supramolecolari per la conversione dell’energia luminosa”) in Italy.
We are grateful to Dr. N. Oberbeckmann-Winter for experimental help,
[9] J. Powell, C. J. May, J. Am. Chem. Soc. 1982, 104, 2636–2637.
[10] A. M. Z. Slawin, M. B. Smith, J. D. Woollins, Chem. Commun. 1996,
2095–2096.
[11] a) N. Oberbeckmann-Winter, P. Braunstein, R. Welter, Organome-
tallics 2005, 24, 3149–3157; b) P. Braunstein, C. Frison, N. Ober-
Chem. Eur. J. 2007, 13, 10117 – 10128
ꢀ 2007 Wiley-VCH VerlagGmbH & Co. KGaA, Weinheim
www.chemeurj.org
10127

P. Braunstein, P. Ceroni et al.
beckmann-Winter, X. Morise, A. Messaoudi, M. BØnard, M.-M.
Rohmer, R. Welter, Angew. Chem. 2004, 116, 6246–6251; Angew.
Chem. Int. Ed. 2004, 43, 6120–6125.
[18] For some examples, see: a) W. Lu, M. C. W. Chan, N. Zhu, C.-M.
Che, Z. He, K.-Y. Wong, Chem. Eur. J. 2003, 9, 6155–6166; b) C. E.
Buss, K. R. Mann, J. Am. Chem. Soc. 2002, 124, 1031–1039; c) S. M.
Drew, D. E. Janzen, C. E. Buss, D. I. MacEwan, K. M. Dublin, K. R.
Mann, J. Am. Chem. Soc. 2001, 123, 8414–8415.
[12] V. Balzani, V. Carassiti, Photochemistry of Coordination Com-
pounds, Academic Press, London, New York, 1970, p. 432 pp.
[13] J. A. G. Williams, Top. Curr. Chem. 2007, 281, 205–268.
[14] See e.g.: a) F. Barigelletti, A. Juris, V. Balzani, P. Belser, A. von Ze-
lewsky, J. Phys. Chem. 1987, 91, 1095–1098; b) F. Barigelletti, P.
Belser, A. von Zelewsky, A. Juris, V. Balzani, J. Phys. Chem. 1985,
89, 3680–3684.
[15] a) P. J. Giordano, S. M. Fredericks, M. S. Wrighton, D. L. Morse, J.
Am. Chem. Soc. 1978, 100, 2257–2259; b) R. J. Watts, J. S. Harring-
ton, J. van Houten, J. Am. Chem. Soc. 1977, 99, 2179–2187.
[16] M. Wrighton, D. L. Morse, J. Am. Chem. Soc. 1974, 96, 998–1003.
[17] Emission quantum yields cannot be measured with our experimental
equipment, but the data reported correspond to an average of multi-
ple emission spectra recorded without movingthe sample from the
spectrofluorimeter. Therefore, the different emission intensities of
the solid sample in different experimental conditions are meaningful
within the large experimental error (20%).
[19] F. R. Hartley, The Chemistry of Platinum and Palladium; Applied
Science Publishers: London, 1973.
[20] R. Uson, A. Laguna, M. Laguna, Inorg. Synth. 1989, 26, 85.
[21] a) A. Apfelbacher, P. Braunstein, L. Brissieux, R. Welter, Dalton
Trans. 2003, 1669–1674; b) P. Veya, C. Floriani, A. Chiesi-Villa, C.
Guastini, A. Dedieu, F. Ingold, P. Braunstein, Organometallics 1993,
12, 4359–4367.
[22] Bruker-Nonius, Kappa CCD Reference Manual, Nonius BV, The
Netherlands, 1998.
[23] M Sheldrick; SHELXL-97, Program for crystal structure refinement;
University of Gçttingen: Germany, 1997.
Received: July 14, 2007
Published online: October 15, 2007
10128
www.chemeurj.org
ꢀ 2007 Wiley-VCH VerlagGmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2007, 13, 10117 – 10128