Five- and Seven-membered metallacycles in [C,N,N′] and [C,N] Cycloplatinated Compounds

Article abstract of DOI:10.1021/om800864f

The reactions of cs-[Pt(4-C₆H4Me)₂(μ- SEt₂)]₂ with ligands ArCH=NCH₂CH ₂NMe₂ (Ar = 4-CIC₆H4 (la); 2-BrC ₆H₄ (lb); 2,6-Cl₂C₆H₃ (1c); C₆F₅ (1d)) and ArCH=NCH₂(4-ClC ₆H4) (Ar = 4-ClC₆H₄ (1e); 2-BrC ₆H₄ (If); 2,6-Cl₂C₆H₃ (1g); C₆F₅ (1h)) were studied. Several types of compounds were formed including (i) [N,N'] coordination compounds (2a, 2c, 2d), (ii) [C,N,N'] platinum(IV) (3b, 3c), [C,N,N'] platinum(II) (4a), and [C,N] platinum(Π) (4e) cyclometalated compounds with a five-membered metallacycle, and (iii) [C,N,N'] platinum(Π) (5c) and [C,N] platinum(Π) (5f, 5g) cyclometalated compounds with a seven-membered metallacycle. The reactions of the obtained cyclometalated compounds with triphenylphosphine were studied, and the new compounds were fully characterized including structure determinations for 4a, 5c, 5g, and the phosphine derivative 7 g'. The ease of formation of seven-membered metallacycles is discussed on the basis of the structure of the ligand (terdentate versus bidentate) and the C-X bond to be activated.

Full text of DOI:10.1021/om800864f

Organometallics 2009, 28, 587–597
587
Five- and Seven-Membered Metallacycles in [C,N,N′] and [C,N]
Cycloplatinated Compounds
Raquel Mart´ın and Margarita Crespo*
Departament de Qu´ımica Inorga`nica, UniVersitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain
Merce` Font-Bardia and Teresa Calvet
Departament de Cristal · lografia, Mineralogia i Dipo`sits Minerals, UniVersitat de Barcelona, Mart´ı i
Franque`s s/n, 08028 Barcelona, Spain
ReceiVed September 5, 2008
The reactions of cis-[Pt(4-C6H4Me)2(µ-SEt2)]2 with ligands ArCHdNCH2CH2NMe2 (Ar ) 4-ClC6H4
(1a); 2-BrC6H4 (1b); 2,6-Cl2C6H3 (1c); C6F5 (1d)) and ArCHdNCH2(4-ClC6H4) (Ar ) 4-ClC6H4 (1e);
2-BrC6H4 (1f); 2,6-Cl2C6H3 (1g); C6F5 (1h)) were studied. Several types of compounds were formed
including (i) [N,N′] coordination compounds (2a, 2c, 2d), (ii) [C,N,N′] platinum(IV) (3b, 3c), [C,N,N′]
platinum(II) (4a), and [C,N] platinum(II) (4e) cyclometalated compounds with a five-membered
metallacycle, and (iii) [C,N,N′] platinum(II) (5c) and [C,N] platinum(II) (5f, 5g) cyclometalated compounds
with a seven-membered metallacycle. The reactions of the obtained cyclometalated compounds with
triphenylphosphine were studied, and the new compounds were fully characterized including structure
determinations for 4a, 5c, 5g, and the phosphine derivative 7 g′. The ease of formation of seven-membered
metallacycles is discussed on the basis of the structure of the ligand (terdentate versus bidentate) and the
C-X bond to be activated.
for adequate N-donor ligands when cis-[PtPh2(dmso)2],3
cis-[PtPh2(SMe2)2],4,5 cis-[Pt(3,5-R2C6H3)2(dmso)2] (R ) Me,
CF3),6 or trans-[Pt(2,4,6-Me3C6H2)2(dmso)2]7 is used. On the
other hand, reactions involving intramolecular C-Br activation
and elimination of 4,4′-bitolyl have been reported as a conve-
nient method for the synthesis of [N,C,N] cyclometalated
platinum(II) compounds8 when substrate cis-[Pt(4-C6H4Me)2(µ-
SEt2)]2 was used. Finally, processes leading to elimination of 1
equiv of benzene along with formal insertion of one phenyl
ligand in the metallacycle have been reported upon reaction of
cis-[PtPh2(SMe2)2] with N-donor ligands for which C-Br or
C-Cl bond activation is possible.4 The latter process leads to
formation of seven-membered metallacycles (see method a in
Scheme 1), and it is interesting to point out that this type of
metallacycle has also been obtained in a process using cis-
[PtCl2(dmso)2] as metalating agent and involving intermolecular
Introduction
Palladium and platinum cyclometalated compounds with
nitrogen donor ligands attract a great deal of interest due to
their numerous applications in several fields, such as organic
and organometallic synthesis, the design of new metallome-
sogens, and biologically active compounds.1 An interesting
feature of platinum derivatives is that, in addition to square-
planar platinum(II) compounds, octahedral platinum(IV) com-
plexes may also be obtained; this fact has stimulated the
development of electron-rich platinum precursors such as
[Pt2Me4(SMe2)2],2 which are able to produce either platinum(II)
or platinum(IV) compounds.
Several diarylplatinum(II) compounds have also been tested
as metalating agents and shown to produce different types of
reactions. A process involving intramolecular C-H activation
and loss of 1 equiv of the corresponding arene has been reported
(3) (a) Minghetti, G.; Stoccoro, S.; Cinellu, M. A.; Soro, B.; Zucca, A.
Organometallics 2003, 22, 4770. (b) Zucca, A.; Doppiu, A.; Cinellu, M. A.;
Stoccoro, S.; Minghetti, G.; Manassero, M. Organometallics 2002, 21, 783.
(4) (a) Crespo, M.; Font-Bardia, M.; Solans, X. Organometallics 2004,
23, 1708. (b) Font-Bardia, M.; Gallego, C.; Martinez, M.; Solans, X.
Organometallics 2002, 21, 3305. (c) Gallego, C.; Martinez, M.; Safont,
V. S. Organometallics 2007, 26, 527.
(5) Crespo, M.; Font-Bardia, M.; Solans, X. J. Organomet. Chem. 2006,
691, 1897.
(6) Yagyu, T.; Ohashi, J.; Maeda, M. Organometallics 2007, 26, 2383.
(7) Sarkar, B.; Schurr, T.; Hartenbach, I.; Schleid, T.; Fiedler, J.; Kaim,
W. J. Organomet. Chem. 2008, 693, 1703.
(8) (a) Rodr´ıguez, G.; Albrecht, M.; Schoenmaker, J.; Ford, A.; Lutz,
M.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 2002, 124, 5127. (b)
Albrecht, M.; Rodr´ıguez, G.; Schoenmaker, J.; van Koten, G. Org. Lett.
2000, 2, 3461. (c) Canty, A. J.; Patel, J.; Skelton, B. W.; White, A. H. J.
Organomet. Chem. 2000, 599, 195. (d) Slagt, M. Q.; Gebbink, R. J. M. K.;
Lutz, M.; Spek, A. L.; van Koten, G. J. Chem. Soc., Dalton Trans. 2002,
2591.
* Corresponding author. Phone: +34934039132. Fax: +34934907725.
E-mail: margarita.crespo@qi.ub.es.
(1) (a) Ryabov, A. D. Synthesis 1985, 233. (b) Dupont, J.; Pfeffer, M.;
Spencer, J. Eur. J. Inorg. Chem. 2001, 1917. (c) Dupont, J.; Consorti, C. S.;
Spencer, J. Chem. ReV. 2005, 105, 2527. (d) Omae, I. Coord. Chem. ReV.
2004, 248, 995. (e) Espinet, P.; Esteruelas, M. A.; Oro, L. A.; Serrano,
J. L.; Sola, E. Coord. Chem. ReV. 1992, 117, 215. (f) Navarro-Ranninger,
C.; Lo´pez-Solera, I.; Pe´rez, J. M.; Masaguer, J. R.; Alonso, C. Appl.
Organomet. Chem. 1993, 7, 57. (g) Albrecht, M.; van Koten, G. Angew.
Chem., Int. Ed. 2001, 40, 3750.
(2) (a) Anderson, C. M.; Crespo, M.; Jennings, M. C.; Lough, A. J.;
Ferguson, G.; Puddephatt, R. J. Organometallics 1991, 10, 2672. (b) Crespo,
M.; Martinez, M.; Sales, J.; Solans, X.; Font-Bardia, M. Organometallics
1992, 11, 1288. (c) Crespo, M.; Martinez, M.; Sales, J. Organometallics
1993, 12, 4297. (d) Crespo, M.; Solans, X.; Font-Bardia, M. Organometallics
1995, 14, 355. (e) Baar, C. R.; Jenkins, H. A.; Vittal, J. J.; Yap, G. P. A.;
Puddephatt, R. J. Organometallics 1998, 17, 2805. (f) Baar, C. R.; Hill,
G. S.; Vittal, J. J.; Puddephatt, R. J. Organometallics 1998, 17, 32.
10.1021/om800864f CCC: $40.75
2009 American Chemical Society
Publication on Web 12/11/2008

588 Organometallics, Vol. 28, No. 2, 2009
Mart´ın et al.
Scheme 1
activation of toluene used as a solvent,9 as shown in method b
in Scheme 1. These reactions involve formation of a C-C bond
leading to a biaryl linkage, which is an important process in
organic synthesis.10
conformation across the CdN bond since a cross-peak signal
between the imine and the methylene protons was observed. E
to Z isomerization in solution was followed by 1H NMR
spectroscopy at room temperature for compounds 2a and 2c,
as shown in Scheme 3. For 2a, after 96 h, the ratio of the isomers
was E:Z ) 1:1.9. For 2c, the process was more complex since,
in addition to E-Z isomerization, cyclometalated platinum(IV)
compound [PtCl(4-MeC6H4)2{2-ClC6H3CHNCH2CH2NMe2}]
(3c) arising from intramolecular C-Cl oxidative addition and
containing a terdentate [C,N,N′] ligand was formed. In this case,
In order to gain insight into the different processes that might
take place when diarylplatinum compounds are used as meta-
lating substrates, the study of the reactions of cis-[Pt(4-
C6H4Me)2(µ-SEt2)]2 with imines of general formulas ArCHd
NCH2CH2NMe2 and ArCHdNCH2(4-ClC6H4) in which the aryl
group Ar may contain either Br, Cl, H, or F in the ortho
positions was envisaged. The aim of this work is to evaluate
how both the nature of the ortho C-X bonds and the different
structure of the ligands, containing either two or one nitrogen
atoms, influence the obtained results. Dinuclear compound cis-
[Pt(4-C6H4Me)2(µ-SEt2)]2, previously used as metalating agent
as stated above,8 was selected for this study since the presence
of an electron-donor methyl substituent in the aryl ring facilitates
the activation of the ortho C-X bonds6 as well as the spectral
characterization of the products by means of NOE interactions
in which the methyl is involved. In addition, a comparison with
the compounds arising from intermolecular activation of toluene9
could be drawn, thus allowing for a better understanding of these
processes.
1
after 24 h, the H NMR spectrum indicated disappearance of
the E isomer and the presence of both the Z isomer and
compound 3c as the main product. After 120 h, conversion to
compound 3c was complete.
The reaction of cis-[Pt(4-C6H4Me)2(µ-SEt2)]2 with ligand 1b
in toluene at room temperature produced compound [PtBr(4-
MeC6H4)2{C6H4CHNCH2CH2NMe2}] (3b) as a white solid, in
an analogous process to that described for 3c, which involves
coordination of the ligand, followed by intramolecular oxidative
addition of a C-Br bond. In this case, the corresponding
coordination compound could not be isolated, or even detected
in solution, and this fact is consistent with the higher reactivity
of a C-Br versus C-Cl or C-H bond.4a,11
In an attempt to obtain cyclometalated platinum(II) com-
pounds, coordination precursors 2a and 2c were treated in
toluene under reflux for 6 h to produce, respectively, compounds
[Pt(4-MeC6H4){4-ClC6H3CHNCH2CH2NMe2}] (4a) and
[PtCl{(MeC6H3)(ClC6H3CHNCH2CH2NMe2}] (5c). The pro-
posed structures, shown in Scheme 2, contain a terdentate
[C,N,N′] ligand. The former arises from intramolecular C-H
bond activation and elimination of a toluene molecule to yield
a five-membered metallacycle, while the latter is formed in a
more complex process involving formation of a C-C bond
between two aryl rings and formation of a seven-membered
platinacycle.4
Results and Discussion
Reactions with Ligands ArCHdNCH2CH2NMe2 (Ar )
4-ClC6H4 (1a); 2-BrC6H4 (1b); 2,6-Cl2C6H3 (1c); C6F5
(1d)). The reactions of cis-[Pt(4-C6H4Me)2(µ-SEt2)]2 with
ligands 1a, 1c, or 1d in toluene at room temperature produced
compounds [Pt(4-C6H4Me)2(Me2NCH2CH2NCHAr)] (2a, 2c,
2d) containing a bidentate [N,N′] ligand as yellow solids (see
Scheme 2). 1H-1H NOESY experiments indicated an E
(9) (a) Capape´, A.; Crespo, M.; Granell, J.; Vizcarro, A.; Zafrilla, J.;
Font-Bard´ıa, M.; Solans, X. Chem. Commun. 2006, 4128. (b) Capape´, A.;
Crespo, M.; Granell, J.; Font-Bard´ıa, M.; Solans, X. Dalton Trans. 2007,
2030.
(10) (a) Nicolaou, K. C.; Bulger, P. G.; Sarlah, D. Angew. Chem., Int.
Ed. 2005, 44, 4442. (b) Bedford, R. B. Chem. Commun. 2003, 1787. (c)
Bedford, R. B.; Cazin, C. S. J.; Holder, D. Coord. Chem. ReV. 2004, 248,
2283. (d) Godula, K.; Sames, D. Science 2006, 312, 67.
Under analogous conditions, no reaction was observed for
ligand C6F5CHdNCH2CH2NMe2 (1d), which can be related to
the combined effects of the inertness of the C-F bond and the
(11) Benson, S. W. Thermochemical Kinetics; Wiley: New York, 1976.

[C,N,N′] and [C,N] Cycloplatinated Compounds
Organometallics, Vol. 28, No. 2, 2009 589
Scheme 2
Scheme 3
membered metallacycles such as compound 5c, the behavior
of compound [PtCl(4-MeC6H4)2{2-ClC6H3CHNCH2CH2NMe2}]
(3c) in refluxing toluene was also studied. It was confirmed that
compound 5c can be obtained from compound 3c, although
along with some decomposition leading to metallic platinum
and lower yields than for the direct synthesis from 2c. Under
the same reaction conditions, compound 3b reacted very slowly,
and concomitant decomposition processes prevented isolation
of the corresponding seven-membered derivative.
The new compounds were characterized by elemental analy-
ses, ESI mass spectra, and NMR spectroscopy, and compounds
4a and 5c were also characterized crystallographically. In most
cases, {1H-1H} COSY and NOESY NMR spectra were taken
1
and allowed for a full assignment of the H NMR signals.
For compounds 2, the J(H-Pt) value for the imine is higher
for the E (ca. 40-50 Hz) than for the Z (ca. 26 Hz) isomers, in
agreement with the trans arrangement for the former.5,13 The
ortho hydrogen atoms in the tolyl ligands are also coupled to
platinum, and the J(H-Pt) values are smaller for the group trans
to the imine, in agreement with the higher trans influence of
imine versus amine.
For octahedral platinum(IV) compounds 3, distinct features
are observed. As expected, the J(H-Pt) values observed for
the imine and the tolyl ortho hydrogen atoms decrease when
compared to related platinum(II) compounds.14 As a result of
unfavorable steric effects of the tolyl groups. Although the C-F
bond has been activated upon reaction of analogous ligands with
platinum substrate [Pt2Me4(µ-SMe2)2],12 no reaction has been
observed when cis-[PtPh2(SMe2)2] was used.4a
In order to prove whether the formation of platinum(IV)
compounds is involved in the mechanism of formation of seven-
(12) (a) Anderson, C. M.; Crespo, M.; Ferguson, G.; Lough, A. J.;
Puddephatt, R. J. Organometallics 1992, 11, 1177. (b) Lo´pez, O.; Crespo,
M.; Font-Bardia, M.; Solans, X. Organometallics 1997, 16, 1233.
(13) Crespo, M.; Font-Bardia, M.; Granell, J.; Martinez, M.; Solans, X.
Dalton Trans. 2003, 3763.
(14) Crespo, M.; Puddephatt, R. J. Organometallics 1987, 6, 2548.

590 Organometallics, Vol. 28, No. 2, 2009
Mart´ın et al.
Scheme 4
the lack of symmetry plane, the methyl and methylene groups
of the coordinated ligand are nonequivalent. Resonances of the
tolyl ligands were assigned on the basis of the 2D-NOESY
experiment carried out for 3b, in which the ortho hydrogen
atoms of the equatorial tolyl display cross-peaks with both
methyl groups of the dimethylamino moiety, while the axial
tolyl with only one of them.
For platinum(II) derivatives 4a and 5c, both the imine and
the aromatic hydrogen adjacent to the metalation site are coupled
to platinum. The remarkably different J(H-Pt) values for the
imine are consistent with the presence of a tolyl (4a, J(H-Pt)
) 56.0 Hz) or a chloro (5c, J(H-Pt) ) 147.7 Hz) ligand in a
trans position. For 5c, as reported for related compounds with
a seven-membered metallacycle,4 the methyl and methylene
groups of the coordinated ligand are nonequivalent. The
{1H-13C}-heterocorrelation spectra of 4a and 5c show respec-
tively five and six cross-peaks in the aromatic region, which is
consistent with the proposed structures. For both 2a and 4a,
the position of the 195Pt resonance within the range expected
for a [C, C, N, N] set of ligands15 confirms the proposed
structures.
Reactions with Ligands ArCHdNCH2(4-ClC6H4) (Ar )
4-ClC6H4 (1e); 2-BrC6H4 (1f); 2,6-Cl2C6H3 (1g); C6F5
(1h)). In order to complete the present study, the reactions of
cis-[Pt(4-C6H4Me)2(µ-SEt2)]2 with ligands 1e, 1f, 1g, and 1h
containing only one nitrogen were also studied (see Scheme
4). Previous work using N-benzylidenbenzylamines with other
metalating agents such as [Pt2Me4(SMe2)2] indicate that, al-
though coordination of the ligand is postulated as a previous
step to the intramolecular C-X bond activation, the corre-
sponding coordination compounds are not usually isolated.2b,c,16
Initially, the reactions were carried out in toluene at room
temperature for 24 h. Under these conditions, imine 1f gave
compound 5f, which contains a seven-membered metallacycle,
while imines 1e and 1g gave mixtures of compounds, which
when submitted to more drastic conditions, evolved to com-
pounds 4e and 5g, respectively. Compound 5g was best obtained
when the platinum substrate and imine 1g were treated in toluene
at 90 °C for 6 h. Compounds 4e, 5f, and 5g contain a bidentate
[C,N] ligand. Compound [Pt(4-MeC6H4){4-ClC6H3CHNCH2(4-
ClC6H4)}SEt2] (4e), which contains a five-membered metalla-
cycle, arises from intramolecular C-H bond activation with
elimination of a molecule of toluene. Compounds [PtBr{(Me-
C6H3)C6H4CHNCH2(4-ClC6H4)}SEt2] (5f) and [PtCl-
{(MeC6H3)(ClC6H3)CHNCH2(4-ClC6H4)}SEt2] (5g) are formed
in processes involving C-X (X ) Br or Cl) oxidative addition,
formation of a C-C bond between the metalated phenyl and a
tolyl ligand, and elimination of one molecule of toluene. No
reaction, other than decomposition and imine hydrolyses when
more drastic conditions were used, was observed for ligand 1h.
As previously indicated for ligand 1d, the lack of reactivity can
be related to the low reactivity of the C-F bond;17 in addition,
the presence of only one nitrogen and the electron-withdrawing
effect of the pentafluoro group prevent the formation of a
coordination compound.
The new compounds were characterized by elemental analy-
ses, ESI mass spectra, and NMR spectroscopy, and compounds
5g was also characterized crystallographically.
In spite of the presence of a bidentate [C,N] ligand and a
diethylsulfide in the coordination sphere of the compounds
described in this section versus a tridentate [C,N,N′] in those
(17) (a) Burdeniuc, J.; Jedlicka, B.; Crabtree, R. H. Chem. Ber. Recl.
1997, 130, 145. (b) Bosque, R.; Clot, E.; Fantacci, S.; Maseras, F.;
Eisenstein, O.; Perutz, R. N.; Renkema, K. B.; Caulton, K. G. J. Am. Chem.
Soc. 1998, 120, 12634.
(15) Pregosin, P. S. Coord. Chem. ReV. 1982, 44, 247.
(16) Crespo, M.; Solans, X.; Font-Bardia, M. J. Organomet. Chem. 1996,
518, 105.

[C,N,N′] and [C,N] Cycloplatinated Compounds
Organometallics, Vol. 28, No. 2, 2009 591
Scheme 5
described above, common features are observed for five-
membered metallacycles (4a and 4e) on one side and seven-
membered metallacycles (5c, 5f, and 5g) on the other. As for
4a and 5c, both the imine and the aromatic hydrogen adjacent
to the metalation site are coupled to platinum in compounds
4e, 5f, and 5g. For 5f and 5g, the J(H-Pt) values for the imine
are lower (ca. 120 Hz) than that observed for 5c (J(H-Pt) )
147.7 Hz), in agreement with the presence of a diethylsulfide
ligand in a trans position. For 5f and 5g, the methylene groups
of the coordinated ligand are nonequivalent. The {1H-13C}-
heterocorrelation spectra of 4j, 5f, and 5g show respectively
seven, nine, and eight cross-peaks in the aromatic region, which
is consistent with the proposed structures.
and the reactions with triphenylphosphine indicate that the
entering ligand is initially placed trans to the metalated carbon
to yield 7f and 7g, respectively, which later isomerize to the
more stable 7f′ and 7g′, in which the phosphine is trans to the
N atom. For 5f, the reaction produced initially isomer 7f only,
which later isomerizes in solution to 7f′. The reaction of 5g
with triphenylphosphine was monitored by NMR spectroscopy,
and it was observed that before the replacement of the SEt2
ligand was complete, both isomers 7g and 7g′ were formed.
Within 4 h, the substitution process was complete and the ratio
of isomers 7g:7g′ was 2.3:1.0; after 140 h in solution, the ratio
was 0.7:1.0. Isomer 7g′ crystallized in dichloromethane-methanol.
The obtained results suggest that although steric effects of the
bulky triphenylphosphine might be responsible for the initial
formation of compounds 7f and 7g, these isomerize to the more
stable species according to the transphobia model.
Reactions with Triphenylphosphine. The reactions of
compounds 3b, 4a, 4e, 5c, 5f, and 5g with triphenylphosphine
were carried out in acetone at room temperature (see Schemes
5 and 6).
For compounds 4a and 4e, the PPh3 replaces either the
dimethylamino moiety or the diethylsulfide ligand in the
coordination sphere of platinum to yield, respectively, com-
pounds 6a and 6e. An analogous process was observed for
compound 5c; however, in this case, two isomers in a 1:1 ratio
were formed as reaction products. This result arises from the
fact that replacement of NMe2 for PPh3 yields compound 7c
with the PPh3 trans to a tolyl group, and this compound
isomerizes to 7c′, in which the PPh3 is trans to the imine, a
more stable situation according to the transphobia18 and the
trans-choice19 models. In agreement with the higher stability
of isomer 7c′, after 18 h in solution the ratio 7c′:7c is 3:1. As
for 5f and 5g, the SEt2 ligand is trans to the N atom, in
agreement with the transphobia and the trans-choice models,
Under the same conditions, compound 3b led to nearly
quantitative recovery of the initial compound. A new signal
observed in the 1H NMR spectra of the crude product is
consistent with formation of compound 8b, which was formed
in a very small extension, indicating a high stability of the
terdentate [C,N,N′] platinum(IV) compound. In an attempt to
displace the reaction, a PPh3:3b ) 2:1 ratio was used; however
under these conditions compound trans-[PtBr(4-CH3C6H4)-
(PPh3)2] was formed.
Phosphine derivatives were characterized by 1H and 31P NMR
spectra; in order to achieve a full assignment {1H-1H} COSY
and NOESY experiments were also carried out for 7c and 7c′.
For compounds 6, the imine proton is a singlet coupled to
platinum and the J(H-Pt) values are very similar to those
observed for the parent compounds 4. The J(P-Pt) values (ca.
2200 Hz) indicate that the PPh3 is trans to the aryl group rather
(18) Vicente, J.; Abad, J. A.; Mart´ınez-Viviente, E.; Jones, P. G.
Organometallics 2002, 21, 4454.
(19) Cuevas, J. V.; Garc´ıa-Herbosa, G.; Miguel, D.; Mun˜oz, A. Inorg.
Chem. Commun. 2002, 5, 340.

592 Organometallics, Vol. 28, No. 2, 2009
Mart´ın et al.
Scheme 6
than to the nitrogen atom.20 Isomers 7 and 7′ show distinct
features in both the 1H and 31P NMR spectra. The imine appears
as a singlet with a coupling to platinum of ca. 140 Hz for
compounds 7 and as a doubletsdue to coupling with the
phosphorus atomswith a reduced J(H-Pt) value (ca. 88 Hz)
for compounds 7′. These data as well as the different J(P-Pt)
values observed in the 31P NMR spectra (ca. 1860 Hz for
compounds 7 and ca. 4300 Hz for compounds 7′) are consistent
with the position of the phosphine trans either to the metalated
carbon or to the nitrogen atoms.20
For compounds 6 and 7, the NMR spectra did not show the
presence of compounds with two coordinated phosphine ligands,
even when an excess of the phosphine was present. This fact
suggests that both the five-membered and the seven-membered
metallacycles are stable and not easily cleaved upon reaction
with phosphines.
Crystal Structures. Suitable crystals of compounds 4a, 5c,
5g, and 7g′ were grown from dichloromethane-methanol at
room temperature.
The crystal structures are composed of discrete molecules
separated by van der Waals distances. Compound 5c crystallizes
with one molecule of CH2Cl2. The structures are shown in
Figures 1, 2, 3, and 4, and selected molecular dimensions are
listed in Table 1. Compound 4a displays disorder in the positions
of atoms C(16) and C(17).
The molecular structures confirm the geometries predicted
from spectroscopic data. Square-planar coordination of the
platinum(II) is achieved with a terdentate [C,N,N′] and a tolyl
(4a) or a chloro (5c) ligand, or with a bidentate [C,N], a chloro,
and a diethylsulfide (5g) or a triphenylphosphine (7g′) ligand.
For 5c, 5g, and 7g′ the metallacycle consists of a nonplanar
seven-membered system in which the imine functionality and
Figure 1. Molecular structure of compound 4a.
two aryl rings tilted 50.6(2)° (5c), 55.2(2)° (5g), or 51.9(2)°
(7g′) from each other are included. For 4a, the five-membered
metallacycle contains the imine functionality and the sum of
internal angles is 540.0°, which suggest a planar arrangement
for the endo-metallacycle.21 The dihedral angle between the
mean planes of the metallacycle and the coordination plane is
3.9(2)°, and the tolyl ligand is tilted from the coordination plane
by 59.8(3)°.
(20) Pregosin, P. S.; Kunz, R. W. In 31P and 13C NMR of Transition
Metal Phosphine Complexes; Diehl, P., Fluck, E., Kosfeld, R., Eds.;
Springer-Verlag: Berlin, 1979.
(21) Klein, H. F.; Camadanli, S.; Beck, R.; Leukel, D.; Flo¨rke, U. Angew.
Chem., Int. Ed. 2005, 44, 975.

[C,N,N′] and [C,N] Cycloplatinated Compounds
Organometallics, Vol. 28, No. 2, 2009 593
Figure 2. Molecular structure of compound 5c.
Figure 4. Molecular structure of compound 7g′.
Conclusions
Previous work using cis-[Pt(4-C6H4Me)2(µ-SEt2)]2 as meta-
lating agent involved oxidative addition to give a platinum(IV)
compound, followed by reductive elimination of 4,4′-bitolyl,
consistent with the expected instability of triarylplatinum(IV)
systems.8 However, this process or the also plausible aryl-
halogen elimination23 was not observed in the present study.
In addition to [N,N′] coordination compounds (2a, 2c, 2d),
cyclometalated compounds with a five-membered metallacycle
(such as [C,N,N′] platinum(IV) (3b, 3c) and platinum(II) (4a)
as well as [C,N] platinum(II) (4e) complexes) or with a seven-
membered metallacycle (such as [C,N,N′] platinum(II) (5c) and
[C,N] platinum(II) (5f, 5g) complexes) were obtained.24
A
general scheme showing the processes leading to such com-
pounds is presented (Scheme 7) for potentially tridentate ligands.
Analogous processes in which the diamine moiety is replaced
by a SEt2 ligand should take place for the bidentate ligand.
Five-membered rings are the most commonly formed in
cyclometalation reactions due to their high stability. The seven-
membered rings are novel examples of a recently reported
process4 involving formal aryl insertion into the metallacycle
with reductive elimination of an arene molecule in a process in
which a C-C bond is formed. The results here reported support
that formation of seven-membered metallacycles may arise from
both C-Br and C-Cl intramolecular activation in both poten-
tially terdentate or bidentate ligands. For ligand 1c, the
corresponding platinum(IV) compound 3c was shown to be an
intermediate in the formation of compound 5c. On the basis of
the observation that 5f and 5g were easily formed, we may
conclude that the process is more facile for bidentate than for
tridentate ligands. Assuming that a vacant site in the coordination
Figure 3. Molecular structure of compound 5g.
Bond lengths and angles are well within the range of values
obtained for analogous compounds. In particular, the Pt-C
bonds are in the range of values found for other aryl complexes
of platinum(II)4,9 and the Pt-amine distances are larger (2.177
and 2.204 Å) than platinum-imine distances (1.959-2.082 Å),
consistent with the weaker ligating ability of amines for
platinum.22 The Pt-Cl bond in 5c (2.315 Å) is shorter than in
5g (2.414 Å) and 7g′ (2.399 Å), in agreement with the presence
of either a nitrogen or a carbon atom in a trans position. Most
bond angles at platinum are close to the ideal value of 90°, and
the smallest angles correspond to N(2)-Pt-N(1) (82.31(14)°
for5cand81.4(2)°for4a)andtothemetallacycle(C(8)-Pt-N(1)
) 81.3(2)° for 4a, C(1)-Pt-N ) 85.40(16)° for 5g, and
C(1)-Pt-N ) 86.53(15) for 7g′). For [C,N,N′] compounds,
the metallacycle angle is larger for seven- than for five-
membered metallacycles (92.90(15)° for 5c versus 81.3(2)° for
4a).
(23) (a) Vigalok, A. Chem.-Eur. J. 2008, 14, 5102. (b) Yahav-Levi,
A.; Goldberg, I.; Vigalok, A.; Vedernikov, A. N. J. Am. Chem. Soc. 2008,
130, 724.
(24) In order to rule out the possibility that the tolyl groups in the
products could arise from the toluene used as a solvent, the syntheses of
4a and 5f were also carried out successfully in benzene.
(22) Capape´, A.; Crespo, M.; Granell, J.; Font-Bardia, M.; Solans, X.
J. Organomet. Chem. 2005, 690, 4309.

594 Organometallics, Vol. 28, No. 2, 2009
Mart´ın et al.
Table 1. Selected Bond Lengths (Å) and Angles (deg.) for Compounds 4a, 5c, 5g, and 7g′ with Estimated Standard Deviations
compound 4a compound 5c compound 5g compound 7g′
2.004(4) 2.017(4)
Pt-C(8)
Pt-C(1)
Pt-N(2)
Pt-N(1)
1.976(5)
2.026(6)
2.177(5)
2.014(5)
Pt-C(1)
Pt-Cl(1)
Pt-N(2)
Pt-N(1)
1.978(4)
2.315(3)
2.204(3)
1.959(4)
Pt-C(1)
Pt-Cl(1)
Pt-N
Pt-C(1)
Pt-Cl(1)
Pt-N
2.4144(14)
2.031(3)
2.2719(14)
2.3993(12)
2.082(3)
2.2417(11)
Pt-S
Pt-P
C(8)-Pt-C(1)
C(8)-Pt-N(1)
C(1)-Pt-N(2)
N(2)-Pt-N(1)
97.6(2)
81.3(2)
99.7(2)
81.4(2)
C(1)-Pt-Cl(1)
Cl(1)-Pt-N(2)
C(1)-Pt-N(1)
N(2)-Pt-N(1)
92.46(12)
92.55(11)
92.90(15)
82.31(14)
C(1)-Pt-N
C(1)-Pt-S
N-Pt-Cl(1)
S-Pt-Cl(1)
85.40(16)
88.33(13)
88.95(11)
97.77(5)
C(1)-Pt-N
C(1)-Pt-P
N-Pt-Cl(1)
P-Pt-Cl(1)
86.53(15)
92.69(12)
87.71(9)
93.07(4)
Scheme 7
sphere of platinum is required for the process leading to
compounds 5, the higher lability of the SEt2 should favor the
process. Conversely, the failure to transform easily 3b into a
seven-membered metallacycle can be related to the low tendency
of the chelate dinitrogen ligand to dissociate. This is also
evidenced from the fact that compound 3b is reluctant to react
with PPh3. When an excess of phosphine was used, the reaction
yielded compound trans-[PtBr(4-CH3C6H4)(PPh3)2], which is
analogous to that reported for a reductive elimination process
taking place from octahedral platinum(IV) compound [PtPh2-
Br(C6H4CHdNCH2Ph)SMe2].4b
For both potentially tridentate or bidentate ligands, seven-
membered metallacycles were not formed from intramolecular
C-H or C-F bond activation. The former gave five-membered
metallacycles with loss of 1 equiv of toluene, while the stronger
C-F bond could not be activated.
The methyl substituent in the tolyl group remains para to
the platinum in coordination compounds 2 or in cyclometalated
platinum(IV) or platinum(II) compounds (3 and 4, respectively).
However, for compounds 5 the methyl group is now para to
the formed C-C bond and meta to the platinum center. This is
evidenced from the 1H NMR spectra of compound 5, in which
a singlet coupled to platinum (J(H-Pt) ca. 53 Hz) was observed
and further confirmed in the molecular structures of compounds
5c, 5g, and 7g′. It is interesting to point out that the same
position of the methyl substituent has been observed in the major
isomer formed in the process described in Scheme 1b for
intermolecular toluene activation. The position of the methyl
group is consistent with a process involving C-C coupling
between the carbon atoms bound to platinum of the metalated
aryl ring and the para-tolyl ligand, as expected for a biaryl
reductive elimination from a platinum(IV) compound.
Experimental Section
General Procedures. Microanalyses were performed by the
Servei de Recursos Cient´ıfics i Te`cnics de la Universitat Rovira i
Virgili (Tarragona). Mass spectra were performed at the Servei
d’Espectrometria de Masses (Universitat de Barcelona). Electro-
spray mass spectra were carried out in a LC/MSD-TOF spectrometer
using H2O-CH3CN (1:1) to introduce the sample. NMR spectra
were performed at the Unitat de RMN d’Alt Camp de la Universitat
de Barcelona using Bruker DRX-250 (195Pt, 54 MHz), Varian Unity
300 (1H, 300 MHz; 31P{1H}, 121.4 MHz), Mercury-400 (1H, 400
MHz; 1H-1H-NOESY, 1H-1H-COSY, 1H-13C-gHSQC), and
Varian Inova DMX-500 (1H, 500 MHz; 1H-1H-NOESY, 1H-1H-
1
COSY, H-13C-gHSQC) spectrometers, and referenced to SiMe4
(1H, 13C), H3PO4 (31P), and H2PtCl6 in D2O (195Pt). δ values are
given in ppm and J values in Hz. Abbreviations used: s ) singlet;
d ) doublet; t ) triplet; m ) multiplet; br ) broad; NMR labeling
is as shown in Schemes 2-6.
25
Preparation of the Compounds. cis-[Pt(4-C6H4Me)2(µ-SEt2)]2
and ligands 1a-1j2a,b,9,26 were prepared as reported elsewhere.
(25) Steele, B. R.; Vrieze, K. Trans. Met. Chem. 1977, 2, 140.
(26) Crespo, M.; Mart´ın, R.; Calvet, T.; Font-Bard´ıa, M.; Solans, X.
Polyhedron 2008, 27, 2603.

[C,N,N′] and [C,N] Cycloplatinated Compounds
Organometallics, Vol. 28, No. 2, 2009 595
3
Compound [Pt(4-MeC6H4)2{4-ClC6H4CHNCH2CH2NMe2}] (2a)
was obtained from 45 mg (0.22 mmol) of imine 1a and 100 mg
(0.11 mmol) of compound [Pt2(4-MeC6H4)2(µ-SEt2)2] in toluene.
The mixture was stirred for 4 h at room temperature. The solvent
was removed in a rotary evaporator, and the residue was treated
with ether. The solid was filtered and dried in Vacuo. Yield: 87 mg
(67%). 1H NMR (400 MHz, CDCl3): δ 8.74 [s, 3J(Pt-H3) ) 42.4,
1H, H3]; 7.88 [d, 3J(H1-H2) ) 8.5, 2H, H1]; 7.30 [d, 3J(Pt-H7) )
NMR (500 MHz, CDCl3): δ 8.59 [s, J(Pt-H5) ) 45.6, 1H, H5];
7.56 [d, J(H9-H10) ) 7.6,3J(Pt-H9) ) 33.8, 2H, H9]; 7.35 [dd,
3
3J(H3-H4) ) 7.5,4J(H2-H4) ) 1.5, 1H, H4]; 7.33 [d, J(H1-H2)
3
) 8.0, 1H, H1]; 7.09 [td, 3J(H2-H1,3) ) 7.7,4J(H2-H4) ) 1.6, 1H,
H2]; 7.00 [td, J(H3-H2,4) ) 7.4,4J(H1-H3) ) 1.0, 1H, H3]; 6.94
3
[d, J(H9-H10) ) 7.7, 2H, H10]; 6.63 [m, J(Pt-H) ) 20.4, 4H,
H12,13]; 4.40-4.33 [m, 1H, H7]; 4.31-4.23 [m, 2H, H6]; 2.97 [s,
3J(Pt-H8) ) 10.4, 3H, H8]; 2.81-2.79 [m, 1H, H7′]; 2.47 [s,
3J(Pt-H8′) ) 14.8, 3H, H8′]; 2.34 [s, 3H, H11]; 2.14 [s, 3H, H14].
13C NMR (1H-13C-gHSQC, 400 MHz, CDCl3): δ 170.0 [C5]; 137.2
[C9]; 133.8 [C12]; 132.3 [C1]; 132.2 [C2]; 129.9 [C4]; 127.8 [C10];
127.7 [C13]; 124.3 [C3]; 65.8 [C7]; 52.4 [C6]; 50.6 [C8]; 48.1 [C8′];
20.7 [C11]; 20.3 [C14]. ESI-MS, m/z: 650.14 [M + NH4]+, 633.12
[M + H]+, 552.20 [M - Br]+. Anal. Found (calc for C25H29BrN2Pt):
C: 47.1 (47.47); H: 4.5 (4.62); N: 4.5 (4.43).
3
3
3
3
68.8, J(H7-H8) ) 7.92, 2H, H7]; 6.89 [d, J(H1-H2) ) 8.5, 2H,
3
3
H2]; 6.75 [d, J(H7-H8) ) 7.5, 2H, H8]; 6.73 [d, J(H10-H11) )
8.0, 3J(Pt-H10) ) 73.4, 2H, H10]; 6.22 [d, 3J(H10-H11) ) 7.5, 2H,
H11]; 4.15 [m, J(H4-H5) ) 5.4, 2H, H4]; 2.76 [m, J(H4-H5) )
5.4, 2H, H5]; 2.64 [s, 3J(Pt-H6) ) 18.3, 6H, H6]; 2.19 [s, 3H, H9],
1.93 [s, 3H, H12]. 195Pt NMR (54 MHz, CDCl3): δ -3438.14. ESI-
MS, m/z: 588.18 [M + H]+, 496.11 [M - C7H7]+. Anal. Found
(calc for C25H29ClN2Pt): C: 51.1 (51.06); H: 5.2 (4.97); N: 4.5
(4.76). After standing in solution for 48 h, compound 2a′ was
formed: 1H NMR (400 MHz, CDCl3): δ 8.43 [s, 3J(Pt-H3) ) 26.0,
1H, H3]; 7.40 [d, 3J(H7-H8) ) 8.5, 2H, H7]; 7.31 [d, 3J(H1-H2) )
8.7, 2H, H2]; 7.29 [d, 3J(H7-H8) ) 8.2, 2H, H8]; 7.20 [d,
3
3
Compound [PtCl(4-MeC6H4)2{2-ClC6H3CHNCH2CH2NMe2}]
(3c) was obtained when a solution of compound 2c was stirred in
CH2Cl2 at room temperature for 24 h. 1H NMR (300 MHz, CDCl3):
δ 9.04 [d, J(H4-H5) ) 1.7, J(Pt-H4) ) 46.6, 1H, H4]; 7.47 [d,
3J(H8-H9) ) 7.8,3J(Pt-H8) ) 33.7, 2H, H8]; 7.32 [dd, 3J(H2-H3)
) 6.9,4J(H1-H3) ) 0.7, 1H, H3]; 7.21 [dd, 3J(H1-H2) ) 7.5, 1H,
4
3
3J(H10-H11) ) 8.0, 2H, H10]; 6.75 [d, J(H1-H2) ) 8.7, 2H, H1];
3
6.71 [d, J(H10-H11) ) 8.1, 2H, H11]; 3.97 [m, 2H, H4]; 2.75 [m,
3
H1]; 7.02 [t, J(H2-H1,3) ) 7.8, 1H, H2]; 6.95 [d, J(H8-H9) )
8.3, 2H, H9]; 6.72 [d, 3J(H11-H12) ) 8.3, 2H, H11]; 6.65 [d,
3J(H11-H12) ) 8.3, 2H, H12]; 4.46-4.39 [m, 1H, H6]; 4.32-4.23
3
3
2H, H5]; 2.63 [s, br, 6H, H6]; 2.17 [s, 3H, H9], 2.13 [s, br, 3H,
H12].
[m, 2H, H5]; 2.83 [s, J(Pt-H7) ) 11.2, 3H, H7]; 2.79-2.75 [m,
3
Compound [Pt(4-MeC6H4)2{2,6-Cl2C6H3CHNCH2CH2NMe2}]
(2c) was obtained using the same procedure as that described above
from 57 mg (0.23 mmol) of imine 1c and 104 mg (0.11 mmol) of
compound [Pt2(4-MeC6H4)2(µ-SEt2)2]. Yield: 97 mg (71%). 1H
1H, H6′]; 2.52 [s, J(Pt-H7′) ) 16.2, 3H, H7′]; 2.33 [s, 3H, H10],
3
2.16 [s, 3H, H13].
Compound [Pt(4-MeC6H4){4-ClC6H3CHNCH2CH2NMe2}] (4a)
was obtained from 50 mg (0.09 mmol) of compound 2a after
reaction in toluene at 90 °C for 6 h. The solvent was removed and
the residue was treated with ether to produce a solid, which was
3
NMR (400 MHz, CDCl3): δ 8.69 [s, br, J(Pt-H4) ) 53.5, 1H,
3
3
H4]; 7.24 [d, J(H8-H9) ) 7.9, J(Pt-H8) ) 59.3, 2H, H8]; 6.90
[s, 3H, H1,2,3]; 6.74 [d, 3J(H11-H12) ) 7.9, 2H, H11]; 6.68 [d,
3J(H8-H9) ) 7.4, 2H, H9]; 6.16 [d, J(H11-H12) )7.4, 2H, H12];
3
1
filtered and dried in Vacuo. Yield: 26 mg (62%). H NMR (500
4.17 [td, J(H5-H6) ) 5.6, J(H4-H5) ) 1.5, 2H, H5]; 2.79 [d,
3J(H5-H6) )5.5, 2H, H6]; 2.62 [s, br, 6H, H7]; 2.13 [s, 3H, H10],
1.91 [s, 3H, H13]. 13C NMR (1H-13C-gHSQC, 400 MHz, CDCl3):
δ 160.2 [C4]; 137.8 [C8]; 137.2 [C11]; 130.4 [C2]; 128.1 [C9]; 127.7
[C1,3]; 126.8 [C12]; 64.5 [C5]; 65.4 [C6]; 49.5 [C7]; 21.0 [C10]; 20.6
[C13]. ESI-MS, m/z: 639.14 [M + NH4]+, 622.14 [M + H]+, 530.07
[M - C7H7]+. Anal. Found (calc for C25H28Cl2N2Pt · CH2Cl2): C:
44.7 (44.14); H: 4.2 (4.27); N: 4.0 (3.96). After standing in solution
3
4
MHz, CDCl3): δ 8.45 [d, 4J(H4-H5) ) 1.4, 3J(Pt-H4) ) 56.0, 1H,
H4]; 7.40 [d, 3J(H8-H9) ) 7.8,3J(Pt-H8) ) 57.2, 2H, H8]; 7.16 [d,
3J(H2-H3) ) 8.1, 1H, H3]; 7.08 [d, 3J(Pt-H1) ) 69.4, 3J(H1-H2)
) 2.1, 1H, H1]; 6.96 [d, J(H8-H9) ) 7.5, 2H, H9]; 6.93 [dd,
3
3J(H2-H3) ) 8.0,4J(H1-H2) ) 2.1, 1H, H2]; 4.03 [td, J(H5-H6)
3
) 6.0, J(H4-H5) ) 1.3, 2H, H5]; 3.18 [t, J(H5-H6) ) 6.0, 2H,
4
3
H6]; 2.76 [s, J(Pt-H7) ) 20.9, 6H, H7]; 2.30 [s, 3H, H10]. 13C
3
NMR (1H-13C-gHSQC, 500 MHz, CDCl3): δ 168.5 [C4]; 137.0
[C8]; 135.7 [C1]; 129.0 [C3]; 128.0 [C9]; 122.5 [C2]; 67.1 [C6]; 52.3
[C5]; 49.0 [C7]; 20.8 [C10]. 195Pt NMR (54 MHz, CDCl3): δ
-3580.76. ESI-MS, m/z: 899.15 [2M - C7H7]+, 496.11 [M + H]+,
404.05 [M - C7H7]+. Anal. Found (calc for C18H21ClN2Pt): C: 43.9
(43.60); H: 4.3 (4.27); N: 5.3 (5.65).
1
for a few hours, compound 2c′ was formed: H NMR (400 MHz,
CDCl3): δ 8.36 [t, J(H4-H5) ) 2.2, J(Pt-H4) ) 26.8, 1H, H4];
4
3
{7.31 [d, 3J(H-H) ) 7.6, 2H]; 7.26 [d, 3J(H-H) ) 7.9, 2H]; 6.97
3
3
[d, J(H-H) ) 7.9, 2H]; 6.96 [d, J(H-H) ) 7.9, 2H]; 6.77 [dd,
3J(H-H) ) 8.6, J(H-H) ) 0.7, 1H]; 6.72 [dd, J(H-H) ) 8.2,
4
3
4J(H-H) ) 0.5, 1H]; H1,3,8,9,11,12}; 4.34-4.32 [m, 2H, H5];
Compound [PtCl{(MeC6H3)(ClC6H3CHNCH2CH2NMe2}] (5c)
was obtained from 100 mg (0.16 mmol) of compound 2c after
reaction in refluxing toluene for 6 h. The solvent was removed and
the residue was treated with ether to produce a yellow solid, which
3.64-3.60 [m, 2H, H6]; 2.63 [s, J(Pt-H7) ) 19.3, 6H, H7]; 2.18
3
[s, 3H, H10], 2.13 [s, 3H, H13].
Compound [Pt(4-MeC6H4)2{C6F5CHNCH2CH2NMe2}] (2d) was
obtained using the same procedure as that described above from
59 mg (0.22 mmol) of imine 1d and 101 mg (0.11 mmol) of
compound [Pt2(4-MeC6H4)2(µ-SEt2)2]. Yield: 95 mg (67%). 1H
1
was filtered and dried in Vacuo. Yield: 58 mg (68%). H NMR
(500 MHz, CDCl3): δ 9.22 [s, J(Pt-H4) ) 147.7, 1H, H4]; 7.49
3
[t, 3J(H2-H1,3) ) 7.5, 1H, H2]; 7.44 [s, br, 3J(Pt-H8) ) 53.4, 1H,
H8]; 7.35 [dd, 3J(H1,3-H2) ) 8.1, 3J(H1-H3) ) 0.9, 2H, H1,3]; 6.87
[d, 3J(H10-H11) ) 7.8, 1H, H11]; 6.80 [dd, 3J(H8-H9) ) 8.0,
4J(H8-H10) ) 1.3, 1H, H10]; 4.52 [m, 2J(H5-H5′) ) 11.9,
3J(H5-H6′) ) 3.9, 4J(H4-H5) ) 1.2, 1H, H5]; 3.97 [dd, 2J(H5-H5′)
3
NMR (400 MHz, CDCl3): δ 8.67 [s, J(Pt-H1) ) 48.4, 1H, H1];
3
7.19 [d, J(H5-H6) ) 7.9,3J(Pt-H5) ) 71.0, 2H, H5]; 6.81 [d,
3J(H8-H9) ) 7.9,3J(Pt-H8) ) 76.8, 2H, H8]; 6.7 [d, 3J(H5-H6) )
7.5, 2H, H6]; 6.35 [d, 3J(H8-H9) ) 7.6, 2H, H9]; 4.09 [td,
4
3J(H2-H3) ) 5.1, J(H1-H2) ) 1.5, 2H, H2]; 2.75 [m, 2H, H3];
) 11.7, J(H5′-H6) ) 3.8, J(Pt-H5′) ) 59.9, 1H, H5′]; 3.08 [s,
3H, H7]; 2.73 [s, 3H, H7′]; 2.73 [m, 1H, H6]; 2.60 [td, 2J(H6-H6′)
) 12.9,3J(H5-H6′) ) 4.0, 1H, H6′]; 2.31 [s, 3H, H9]. 13C NMR
(1H-13C-gHSQC, 500 MHz, CDCl3): δ 162.7 [C4]; 139.7 [C8];
132.4 [C1]; 132.1 [C2]; 129.1 [C11]; 127.3 [C3]; 124.8 [C10]; 66.9
[C5]; 65.13 [C6]; 50.5 [C7′]; 47.8 [C7]; 21.0 [C9]. ESI-MS, m/z:
530.07 [M + H]+. Anal. Found (calc for C18H20Cl2N2Pt): C: 41.5
(40.76); H: 3.7 (3.80); N: 5.3 (5.28).
3
3
3
2.61 [s, J(Pt-H4) ) 18.7, 6H, H4]; 2.14 [s, 3H, H7], 1.99 [s, 3H,
H10]. 13C NMR (1H-13C-gHSQC, 400 MHz, CDCl3): δ 152.1 [C1];
137.5 [C5]; 137.4 [C8]; 127.5 [C6]; 126.8 [C9]; 65.4 [C3]; 64.6 [C2];
49.5 [C4]; 20.8 [C7]; 20.4 [C10]. ESI-MS, m/z: 661.18 [M + NH4]+,
644.18 [M + H]+, 552.10 [M - C7H7]+. Anal. Found (calc for
C25H25F5N2Pt): C: 46.3 (46.66); H: 4.1 (3.92); N: 4.1 (4.35).
Compound [PtBr(4-MeC6H4)2{C6H4CHNCH2CH2NMe2}] (3b)
was obtained using the same procedure as that described above
from 57 mg (0.22 mmol) of imine 1b and 102 mg (0.11 mmol) of
compound [Pt2(4-MeC6H4)2(µ-SEt2)2]. Yield: 90 mg (65%). 1H
Compound [Pt(4-MeC6H4){4-ClC6H3CHNCH2(4-ClC6H4)}SEt2]
(4e) was obtained from 70 mg (0.26 mmol) of imine 1e and 124
mg (0.13 mmol) of compound [Pt2(4-MeC6H4)2(µ-SEt2)2] in toluene.

596 Organometallics, Vol. 28, No. 2, 2009
Mart´ın et al.
The mixture was stirred for 24 h at room temperature and then
was heated at 90 °C for 2 h to complete the reaction. The solvent
was removed in a rotary evaporator and the residue was treated
with ether. The yellow solid was filtered and dried in Vacuo. Yield:
115 mg (69%). 1H NMR (400 MHz, CDCl3): δ 8.45 [s, 3J(Pt-H4)
3J(H5-H6) ) 6.0, 2H, H5]; 2.09 [s, 3H, H10]; 1.89 [m, 8H, H6,7].
1
31P NMR (121 MHz, CDCl3): δ 28.06 [s, J(Pt-P) ) 2197.8].
Compound [Pt(4-MeC6H4){4-ClC6H3CHNCH2(4-ClC6H4)}PPh3]
(6e) was prepared from 40 mg (0.06 mmol) of compound 4e and
17 mg (0.06 mol) of triphenylphosphine using an analogous
procedure to that for 6a. Yield: 39 mg (80%). 1H NMR (300 MHz,
3
) 52.0, 1H, H4]; 7.34 [d, J(H6-H7) ) 8.5, 1H, H7]; 7.30-7.26
[m, 3H, H3,6,8]; 7.00 [dd, 3J(H2-H3) ) 8.0, 4J(H1-H2) ) 2.1, 1H,
H2]; 6.87 [d, 3J(H8-H9) ) 7.4, 2H, H9]; 6.81 [d, 3J(Pt-H1) ) 54.4,
4J(H1-H2) ) 2.1, 1H, H1]; 5.12 [s, 2H, H5]; 2.31 [m, 3J(H11-H12)
) 7.4, 4H, H11]; 2.27 [s, 3H, H10]; 1.06 [t, 3J(H11-H12) ) 7.4, 6H,
H12]. 13C NMR (1H-13C-gHSQC, 400 MHz, CDCl3): δ 176.4 [C4];
136.3 [C3]; 136.3 [C6]; 136.1 [C1]; 129.1 [C8]; 128.8 [C7]; 128.8
[C9]; 123.7 [C2]; 61.8 [C5]; 28.7 [C11]; 20.8 [C10]; 13.0 [C12]. ESI-
3
CDCl3): δ 8.18 [s, J(Pt-H4) ) 50.4, 1H, H4]; {7.49-7.42 [m,
6H]; 7.36-7.30 [m, 6H]; 7.24-7.19 [m, 7H] PPh3, H8, H9}; 7.14
[d, 3J(H6-H7) ) 8.4, 2H, H7]; 6.99 [dd, 3J(H2-H3) ) 7.9,
3
4J(H1-H2) ) 2.1, 1H, H2]; 6.89 [m, 1H, H1]; 6.68 [d, J(H6-H7)
3
) 8.4, 2H, H6]; 6.43 [d, J(H2-H3) ) 7.7, 1H, H3]; 4.08 [s, br,
2H, H5]; 2.09 [s, br, 3H, H10]. 31P NMR (121 MHz, CDCl3): δ
1
27.59 [s, J(Pt-P) ) 2200.6]. ESI-MS, m/z: 811.14 [M + H]+.
MS, m/z: 548.03 [M
-
SEt2]+. Anal. Found (calc for
Compound [PtCl{(MeC6H4)(ClC6H3)CHNCH2CH2NMe2}PPh3]
(7c/7c′) was prepared from 40 mg (0.08 mmol) of compound 5c
and 20 mg (0.08 mol) of triphenylphosphine using an analogous
procedure to that for 6a. Yield: 27 mg (42%). 1H NMR (300 MHz,
CDCl3): 7c: δ 8.26 [s, 3J(Pt-H4) ) 140.0, 1H, H4]; 7.65-7.59 [m,
C25H27Cl2NPtS): C: 46.7 (46.95); H: 4.2 (4.26); N: 2.4 (2.19); S:
3.8 (5.01).
Compound [PtBr{(MeC6H3)C6H4CHNCH2(4-ClC6H4)}SEt2] (5f)
was obtained from 68 mg (0.22 mmol) of imine 1e and 100 mg
(0.11 mmol) of compound [Pt2(4-MeC6H4)2(µ-SEt2)2] in toluene.
The mixture was stirred for 24 h at room temperature. The solvent
was removed in a rotary evaporator and the residue was treated
with ether. The yellow solid was filtered and dried in Vacuo. Yield:
3
6H, Har]; 7.50-7.32 [m, 15H, Har]; 6.96 [dd, J(H10-H11) ) 7.6,
4J(H8-H10) ) 2.5, 1H, H10]; 6.78 [d, 3J(H10-H11) ) 7.8, 1H, H11];
3.18 [m, 1H, H5]; 3.03 [m, 1H, H5′]; 2.45 [m, 2H, H6]; 2.31 [s, 3H,
H9]; 1.78 [m, 6H, H7]. 7c′: δ 8.63 [s, 3J(Pt-H4) ) 84.7, 3J(P-H4)
1
3
98 mg (65%). H NMR (400 MHz, CDCl3): δ 8.61 [s, J(Pt-H4)
3
) 11.25, 1H, H4]; 7.42-7.17 [m, 17H, Har]; 7.11 [dd, J(H1-H2)
) 119.4, 1H, H4]; 7.50-7.46 [m, 1H, H7]; 7.38-7.34 [m, 3H,
) 7.6, 4J(H1-H3) ) 0.9, 1H, H1]; 6.70 [d, 3J(H10-H11) ) 7.7, 1H,
H5,6,8]; 7.20 [d, J(H1-H2) ) 8.4, 1H, H1]; 7.15 [d, J(H1-H2) )
8.3, 1H, H2]; 6.82 [d, 3J(H9-H10) ) 7.6, 1H, H9]; 6.71 [d,
3J(H9-H10) ) 7.3, 1H, H10]; 6.22 [s, 3J(Pt-H12) ) 54.4, 1H, H12];
3
3
3
4
H11]; 6.47 [dd, J(H10-H11) ) 7.6, J(H8-H10) ) 0.9, 1H, H10];
6.40 [s, 1H, H8]; 4.77 [m, 1H, H5]; 3.95 [m, 1H, H5′]; 2.93 [m, 2H,
H6]; 2.77 [m, 2H, H6′]; 2.08 [s, 3H, H7]; 1.76 [m, 6H, H9]. 31P
NMR (121 MHz, CDCl3) 7c: δ 18.64 [s, 1J(Pt-P) ) 1866.5]. 7c′:
5.73 [dd, J(H3-H3′) ) 12.7,4J(H3-H4) ) 1.5, 1H, H3]; 4.88 [d,
2
2J(H3-H3′) ) 12.8, J(Pt-H3′) ) 56.9, 1H, H3′]; 3.03 [s, br, 1H,
3
1
δ 15.19 [s, J(Pt-P) ) 4305.1].
H13′]; 2.66 [s, br, 2H, H13]; 2.36 [s, br, 1H, H13′′]; 2.16 [s, 3H,
H11]; 1.59 [s, br, 3H, H14]; 0.96 [s, br, 3H, H14′]. 13C NMR (1H-13C-
gHSQC, 400 MHz, CDCl3): δ 165.68 [C4]; 136.6 [C12]; 131.6 [C1];
131.0 [C7]; 130.2 [C5]; 128.8 [C8]; 128.6 [C2]; 127.9 [C9]; 126.3
[C6]; 124.3 [C10]; 68.3 [C3]; 20.9 [C11]. ESI-MS, m/z: 603.12 [M
- Br]+. Anal. Found (calc for C25H27BrClNPtS): C: 43.7 (43.90);
H: 3.8 (3.98); N: 2.1 (2.05). S: 4.0 (4.69).
Compound [PtBr{(MeC6H3)(C6H4)CHNCH2(4-ClC6H4)}PPh3] (7f/
7f′) was prepared from 40 mg (0.06 mmol) of compound 5f and
17 mg (0.06 mol) of triphenylphosphine using an analogous
1
procedure to that for 6a. Yield: 35 mg (68%). 7f: H NMR (300
MHz, CDCl3): δ 8.24 [s, 3J(Pt-H4) ) 140.9, 1H, H4]; {7.66-7.56
[m, 8H] PPh3, Har}; 7.54-7.52 [m, 1H, H7]; {7.42-7.36 [m, 10H]
3
3
PPh3, Har}; 7.13 [d, J(H1-H2) ) 8.3, 1H, H2]; 7.06 [d, J(H-H)
) 7.4, 1H, Har]; 6.85 [dd, J(H9-H10) ) 7.6, J(H10-H12) ) 2.5,
1H, H10]; 6.72 [d, 3J(H1-H2) ) 8.4, 2H, H1]; 6.67 [s, 3J(H-H) )
8.9, 1H, Har]; 4.21 [d, 2J(H3-H3′) ) 13.3, 1H, H3]; 4.13 [d,
2J(H3-H3′) ) 13.4, 1H, H3′]; 2.18 [s, br, 3H, H11]. 31P NMR (121
MHz, CDCl3): δ 17.76 [s, 1J(Pt-P) ) 1862.2]. 7f′: 1H NMR (300
3
4
Compound [PtCl{(MeC6H3)(ClC6H3)CHNCH2(4-ClC6H4)}SEt2]
(5g) was obtained as a yellow solid from 66 mg (0.22 mmol) of
imine 1g and 101 mg (0.11 mmol) of compound [Pt2(4-MeC6H4)2(µ-
SEt2)2] using an analogous procedure to that for 5f in toluene at 90
1
°C for 6 h. Yield: 126 mg (85%). H NMR (400 MHz, CDCl3): δ
3
4
8.70 [d, J(Pt-H4) ) 120.4, J(H3-H4) ) 1.2, 1H, H4]; 7.41 [t,
3J(H6-H5,7) ) 7.7, 1H, H6]; 7.37 [dd, 3J(H5-H6) ) 8.0, 4J(H5-H7)
) 1.5, 1H, H5]; 7.24 [dd, 3J(H6-H7) ) 7.3, 4J(H5-H7) ) 1.5, 1H,
H7]; 7.20 [d, 3J(H1-H2) ) 8.4, 1H, H1]; 7.12 [d, 3J(H1-H2) ) 8.4,
MHz, CDCl3): δ 8.64 [d, J(Pt-H4) ) 87.7, J(P-H4) ) 11.1,
4J(H3-H4) ) 1.5, 1H, H4]; {7.44-7.36 [m, 2H]; 7.31-7.27 [m,
9H]; 7.16-7.21 [m, 10H]; PPh3, Har}; 6.61 [d, 3J(H9-H10) ) 7.7,
1H, H9]; 6.39 [d, 3J(H9-H10) ) 7.4, 1H, H10]; 5.84 [d, 3J(H3-H3′)
3
4
3
3
1H, H2]; 6.82 [d, J(H8-H9) ) 7.7, 1H, H8]; 6.70 [dd, J(H8-H9)
) 12.4, 1H, H3]; 5.52 [s, J(Pt-H12) ) 59.5, 1H, H12]; 4.88 [dd,
3
) 7.7, J(H9-H11) ) 1.11, 1H, H9]; 6.27 [s, J(Pt-H11) ) 53.0,
4
3
3J(Pt-H3) ) 48.5, J(H3-H3′) ) 12.3,4J(P-H3′) ) 5.2, 1H, H3′];
3
1H, H11]; 5.57 [dd, 2J(H3-H3′) ) 13.0,4J(H3-H4) ) 1.8, 1H, H3];
1.65 [s, br, 3H, H11]. ESI-MS, m/z: 775.16 [M - Br]+.
4.95 [d, J(H3-H3′) ) 12.9,3J(Pt-H3′) ) 54.6, 1H, H3′]; 3.04 [s,
2
Compound [PtCl{(MeC6H3)(ClC6H3)CHNCH2(4-ClC6H4)}PPh3]
(7g/7g′) was prepared from 40 mg (0.06 mmol) of compound 5g
and 17 mg (0.06 mol) of triphenylphosphine using an analogous
br, 1H, H12′]; 2.62 [s, br, 2H, H12]; 2.38 [s, br, 1H, H12′′]; 2.15 [s,
3H, H10]; 1.26 [s, br, 1H, H13]; 0.93 [s, br, 2H, H13′]. 13C NMR
(1H-13C-gHSQC, 400 MHz, CDCl3): δ 163.7 [C4]; 137.2 [C11];
131.8 [C2]; 131.8 [C6]; 128.9 [C1]; 128.9 [C7]; 128.0 [C8]; 127.4
[C5]; 124.4 [C9]; 67.6 [C3]; 21.0 [C10]; 12.5 [C13]; 12.5 [C13′]. ESI-
MS, m/z: 601.03 [M - SEt2 + NH4]+. Anal. Found (calc for
C25H26Cl3NPtS): C: 44.9 (44.55); H: 3.6 (3.89); N: 2.2 (2.08). S:
3.7 (4.76).
1
procedure to that for 6a. Yield: 23 mg (46%). 7g: H NMR (300
3
4
MHz, CDCl3): δ 8.48 [d, J(Pt-H4) ) 138.9, J(H3-H4) ) 1.0,
1H, H4]; {7.70-7.63 [m, 8H]; 7.48-7.44 [m, 4H]; 7.40-7.43 [m,
3
6H]; PPh3, Har}; 7.12 [d, J(H1-H2) ) 8.4, 2H, H1]; 6.86 [dd,
3J(H-H) ) 7.8, 4J(H-H) ) 2.3, 1H, Har]; 6.71-6.67 [m, 2H, Har];
6.69 [d, J(H1-H2) ) 8.4, 2H, H2]; 4.18 [d, J(H3-H3′) ) 13.5,
3
3
Compound [Pt(4-MeC6H4){4-ClC6H3CHNCH2CH2NMe2}PPh3]
(6a) was prepared from 25 mg (0.05 mmol) of compound 4a and
13 mg (0.05 mmol) of triphenylphosphine, which were dissolved
in 30 mL of acetone and allowed to react at room temperature for
2 h. The solvent was removed and the residue was washed with
ether and dried in Vacuo. Yield: 15 mg (39%). 1H NMR (300 MHz,
CDCl3): δ 8.52 [s, 3J(Pt-H4) ) 51.0, 1H, H4]; 7.56-7.49 [m, 6H,
PPh3]; 7.37-7.23 [m, 9H, PPh3]; 6.99 [m, 2H, H1,3]; 6.92 [d,
3J(Pt-H3′) 66.97, 1H, H3′]; 3.95 [dd, 3J(H3-H3′))
)
13.2,4J(H3-H4) ) 1.2, 1H, H3]; 2.19 [s, br, 3H, H10]. 31P NMR
(121 MHz, CDCl3): δ 18.54 [s, 1J(Pt-P) ) 1856.5]. 7g′: 1H NMR
(300 MHz, CDCl3): δ 8.74 [dd, J(Pt-H4) ) 87.1, J(P-H4) )
11.1, 4J(H3-H4) ) 1.6, 1H, H4]; {7.41 [dd, 3J(H-H) ) 8.1,
4J(H-H) ) 1.3, 1H]; 7.37-7.26 [m, 14H]; 7.22-7.17 [m, 6H];
3
4
3
4
7.11 [dd, J(H-H) ) 7.5, J(H-H) ) 1.2, 1H]; PPh3, Har}; 6.60
[d, 3J(H8-H9)
)
7.6, 1H, H8]; 6.38 [dd, 3J(H8-H9)
)
3
3
3J(H8-H9) ) 7.2, 2H, H8]; 6.87 [dd, J(H2-H3) ) 5.8,4J(H1-H2)
7.6,4J(H9-H11) ) 1.1, 1H, H9]; 5.72 [d, J(H3-H3′) ) 12.2, 1H,
) 2.1, 1H, H2]; 6.43 [d, 3J(H8-H9) ) 7.6, 2H, H9]; 3.12 [t,
H3]; 5.55 [s, 3J(Pt-H11) ) 54.5, 1H, H11]; 4.93 [dd, 3J(Pt-H3′) )

[C,N,N′] and [C,N] Cycloplatinated Compounds
Organometallics, Vol. 28, No. 2, 2009 597
Table 2. Crystallographic and Refinement Data for Compounds 4a, 5c, 5g, and 7g′
compound 4a
C18H21ClN2Pt
495.91
compound 5c
compound 5g
compound 7g′
formula
fw
C18H20Cl2N2Pt · CH2Cl2
615.28
C25H26Cl3NPtS
673.97
C39H31Cl3NPPt
846.06
temp, K
293(2)
293(2)
293(2)
293(2)
wavelength, Å
cryst syst
space group
a, Å
b, Å
c, Å
0.71073
monoclinic
P21/c
10.683(4)
14.836(6)
15.174(6)
90
114.29(10)
90
0.71073
0.71073
monoclinic
P21/c
10.998(5)
8.346(3)
27.121(10)
90
91.43(2)
90
2488.6(17); 4
1.799
0.71073
monoclinic
P21/a
11.748(4)
15.925(4)
18.487(4)
90
97.46(2)
90
3429.4(16); 4
1.639
triclinic
j
P1
8.043(8)
11.709(2)
11.828(6)
90.50(3)
109.26(6)
91.57(4)
1051.0(12); 2
1.944
7.190
R, deg
ꢀ, deg
γ, deg
V, Å3; Z
1732.1(12); 4
1.902
8.253
d(calcd), Mg/m3
abs coeff, mm-1
F(000)
6.058
1312
4.401
1664
952
592
rflns coll./unique
data/restraint/params
GOF on F2
R1 (I > 2σ(I))
wR2 (all data)
peak and hole, e Å-3
3829/3829 [R(int) ) 0.0562]
3829/0/221
1.118
0.0462
0.1259
6114/6114 [R(int) ) 0.0399]
6114/2/236
1.075
0.0360
0.0866
23 534/7270
7270/1/280
1.115
0.0399
0.1074
31 396/9622
9622/2/ 407
1.146
0.0374
0.0859
0.756 and -0.646
0.947 and -0.829
0.744 and -0.579
0.510 and -0.614
3
58.6, J(H3-H3′) ) 12.9,4J(P-H3′) ) 5.3, 1H, H3′]; 1.64 [s, br,
detector. Intensities were collected with graphite-monochromatized
Mo KR radiation. The structures were solved by direct methods
using the SHELXS computer program27 and refined by the full-
matrix least-squares method with the SHELXL97 computer program
using 3829 (4a), 6114 (5c), 23 524 (5g), and 31 396 (7g′) reflections
(very negative intensities were not assumed). 5c, 5g, and 7g′ were
refined with a rigid model restraint for some distances around the
platinum center. Further details are given in Table 2.
3H, H10]. 31P NMR (121 MHz, CDCl3): δ 14.82 [s, J(Pt-P) )
1
4363.5]. ESI-MS, m/z: 850.14 [M - Cl + CH3CN]+, 809.12 [M
- Cl]+.
Preparation of compound [PtBr(4-MeC6H4)2{C6H4CHNCH2-
CH2NMe2}PPh3] (8b) was attempted from 54 mg (0.09 mmol) of
compound 3b and 25 mg (0.09 mol) of triphenylphosphine using
1
an analogous procedure to that for 6a. According to the H NMR
(300 MHz, CDCl3) of the crude reaction mixture, the main product
was starting material 3b; a new imine resonance was observed (δ
8.37 [d, 3J(Pt-H) ) 40.30, 4J(P-H) ) 8.40, 1H, H]) and assigned
to 8b. Addition of a further equivalent of PPh3 in order to facilitate
the reaction resulted in formation of compound trans-[PtBr(4-
CH3C6H4)(PPh3)2]: 1H NMR (300 MHz, CDCl3): δ 7.56-7.50 [m,
15H, PPh3]; 7.34-7.20 [m, 15H, PPh3]; 6.47 [d, 3J(Pt-H3) ) 56.1,
Acknowledgment. This work was supported by the
Ministerio de Ciencia y Tecnolog´ıa (project CTQ2006-
02007/BQU).
Supporting Information Available: X-ray crystallographic data
in CIF format for the structure determinations of 4a, 5c, 5g, and
7g′. This material is available free of charge via the Internet at
http://pubs.acs.org.
3
3J(H2-H3) ) 8.0, 2H, H3]; 5.95 [d, J(H2-H3) ) 7.7, 2H, H2];
1.94 [s, 3H, H1]. 31P NMR (121 MHz, CDCl3): δ 24.48 [s, 1J(Pt-P)
) 3141.8]. ESI-MS: 907.16 [M + NH4]+, 851.23 [M -
Br+CH3CN]+, 810.20 [M - Br]+.
OM800864F
X-Ray Structure Analysis. Prismatic crystals were selected and
mounted on an Enraf-Nonius CAD4 four-circle (5c) or on a
MAR345 (4a, 5g, and 7g′) diffractometer with an image plate
(27) Sheldrick, G. M. SHELXS97, A Computer Program for Crystal
Structure Determination; University of Go¨ttingen: Germany, 1997.