Peripherally η1-platinated organometallic porphyrins as building blocks for multiporphyrin arrays

Article abstract of DOI:10.1021/om0305869

The modification of peripherally metalated meso-η¹-platiniometalloporphyrins, such as trans-[PtBr(NiDAPP)(PPh₃)₂] (H₂DAPP = 5-phenyl-10,20-bis(3′,5′-di-tert-butylphenyl)porphyrin), leads to the analogous platinu

Full text of DOI:10.1021/om0305869

Organometallics 2004, 23, 391-399
391
P er ip h er a lly η1-P la tin a ted Or ga n om eta llic P or p h yr in s a s
Bu ild in g Block s for Mu ltip or p h yr in Ar r a ys
Regan D. Hartnell and Dennis P. Arnold*
Synthesis and Molecular Recognition Program, School of Physical and Chemical Sciences,
Queensland University of Technology, G.P.O. Box 2434, Brisbane, Australia 4001
Received August 28, 2003
The modification of peripherally metalated meso-η1-platiniometalloporphyrins, such as
trans-[PtBr(NiDAPP)(PPh3)2] (H2DAPP ) 5-phenyl-10,20-bis(3′,5′-di-tert-butylphenyl)por-
phyrin), leads to the analogous platinum(II) nitrato and triflato electrophiles in almost
quantitative yields. Self-assembly reactions of these meso-platinioporphyrin tectons with
pyridine, 4,4′-bipyridine, or various meso-4-pyridylporphyrins in chloroform generate new
multicomponent organometallic porphyrin arrays containing up to five porphyrin units. These
new types of supramolecular arrays are formed exclusively in high yields and are stable in
solution or in the solid state for extended periods. They were characterized by multinuclear
NMR and UV-visible spectroscopy as well as high-resolution electrospray ionization mass
spectrometry.
In tr od u ction
nation offers a popular synthetic methodology for the
controlled synthesis of large supramolecular entities.
These arrays usually possess well-defined and predict-
able architectures. By this approach and by choosing
complementary components, elaborate multicomponent
arrays may be constructed in a single step from a stoi-
chiometric combination of the individual tectons.4 Por-
phyrins represent ideal building blocks for the synthesis
of oligomeric and polymeric arrays via the self-assembly
technique. They are fairly rigid and prefer planarity,
are easily modified and functionalized, and are able to
coordinate a large number of metals and pseudometals
within their central cavity. There are numerous ex-
amples of supramolecular porphyrinic arrays assembled
through coordination of phosphine groups,5 coordination
to centrally bound Ru(II)6,7 or Zn(II),8 and coordination
to external metal centers such as Pd(II) and Pt(II)9-15
or other metals.16,17 The vast majority of the systems
prepared so far have utilized a “linker” (often a pyridyl
moiety) between the porphyrin macrocycle and the
coordinating metal center. Due to steric constraints
between the porphyrin’s â-hydrogens and the pyridyl
ring, the aromatic group will often lie perpendicular to
the plane of the porphyrin ring. This conformation
reduces the amount of ground-state electronic com-
munication within the molecule, which is often desirable
to control the properties. However, it may also be useful
to have linkers that modify the redox properties of the
porphyrin(s) by more direct interactions. One way of
combining redox control and array construction is to
The rich photochemical and redox properties of por-
phyrins have made them attractive targets for incorpo-
ration into oligomeric and polymeric assemblies that
may exhibit useful photonic or electronic properties.
Thus, there has been much interest recently in the
design, synthesis, and properties of discrete ordered
arrays of porphyrins and metalloporphyrins, and the
work has spanned many disciplines of science.1-3 Gen-
erally, multiporphyrin arrays have been considered as
biomimetic models of several natural systems or as
materials for the transport of energy, electrons, and ions
and as potential catalytic species. Thus, these arrays
are useful whenever a specific arrangement of porphy-
rins and/or metalloporphyrins with low conformational
freedom is desired for the most efficient operation. A
large range of molecular entities has been synthesized
and studied, and these have provided much valuable
knowledge of how electron transfer is affected by factors
such as the separation distance, mutual orientation,
nature of the insulating spacer group, energy gap,
solvent polarity, and nature of the participating donors/
acceptors.1-3 To increase control over solution and solid-
state structural characteristics, most supramolecular
multiporphyrin arrays take advantage of coordination
or covalent bonds, instead of hydrogen bonds with
proteins as found in natural porphyrin-containing sys-
tems. Substitution of weaker hydrogen bonds or van der
Waals forces with stronger chemical bonds has been
successfully utilized to ensure the efficient electronic
coupling in either ground or excited states between the
individual components of the supramolecular system.1-3
The self-assembly of complementary components via
noncovalent interactions such as metal-ligand coordi-
(4) (a) Faul, C. F. J .; Antonietti, M. Adv. Mater. 2003, 15, 673. (b)
Seidel, S. R.; Stang, P. J . Acc. Chem. Res. 2002, 35, 972. (c) Stang, P.
J . Chem. Eur. J . 1998, 4, 19. Olenyuk, B.; Fechtenkotter, A.; Stang,
P. J . J . Chem. Soc., Dalton Trans. 1998, 1707.
(5) (a) Stulz, E.; Maue, M.; Feeder, N.; Teat, S. J .; Ng, Y.-F.; Bond,
A. D.; Darling, S. L.; Sanders, J . K. M. Inorg. Chem. 2002, 41, 5255.
(b) Stulz, E.; Sanders, J . K. M.; Montalti, M.; Prodi, L.; Zaccheroni,
N.; Fabrizi de Biani, F.; Grigiotti, E.; Zanello, P. Inorg. Chem. 2002,
41, 5269. (c) Stulz, E.; Scott, S. M.; Bond, A. D.; Otto, S.; Sanders, J .
K. M. Inorg. Chem. 2003, 42, 3086. (d) Ruhlmann, L.; Giraudeau, A.
Eur. J . Inorg. Chem. 2001, 659. (e) Darling, S. L.; Stulz, E.; Feeder,
N.; Bampos, N.; Sanders, J . K. M. New J . Chem. 2000, 24, 261.
(1) (a) Wojaczynski, J .; Latos-Grazynski, L. Coord. Chem. Rev. 2000,
204, 113. (b) Chen, C.-T. Compr. Supramol. Chem. 1996, 5, 91. (c)
Wasielewski, M. R. Chem. Rev. 1992, 92, 435.
(2) Burrell, A. K.; Officer, D. L.; Plieger, P. G.; Reid, D. C. W. Chem.
Rev. 2001, 101, 2751.
(3) Baldini, L.; Hunter, C. A. Coord. Chem. Rev. 2000, 53, 213.
10.1021/om0305869 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 12/25/2003

392 Organometallics, Vol. 23, No. 3, 2004
Hartnell and Arnold
have the metal fragment directly η1bonded to the
porphyrin macrocycle.
Several types of organometallic porphyrins are known.
The vast majority of examples in this area usually
incorporate the organometallic bond between the cen-
trally bound metal in the porphyrin and an organic
fragment.18 The recent discovery and investigation of
modified porphyrin macrocycles such as inverted or “N-
confused” porphyrins19 and azuliporphyrins20 have some-
what increased the number of examples in this area;
however, the centrally coordinated metal still partici-
pates in the organometallic character of the molecule.
There are also limited examples of porphyrins with an
externally bound organometallic fragment, which in-
clude examples of both σ- and π-bonded organometallic
moieties.21
Apart from the examples of organometallic porphyrins
discussed above, there is another group of η1-organo-
metallic porphyrins that has been synthesized recently.
Our publications have been the only reports of isolated
η1-organopalladio- and η1-organoplatinioporphyrins.22-24
This particular version of late-transition-metal chem-
istry leads to the compounds of type 1, whose palladium-
(6) (a) Iengo, E.; Zangrando, E.; Alessio, E. Eur. J . Inorg. Chem.
2003, 2371. (b) Prodi, A.; Indelli, M. T.; Kleverlann, C. J .; Scandola,
F.; Alessio, E.; Gianferrara, T.; Marzilli, L. G. Chem. Eur. J . 1999, 5,
2668. (c) Prodi, A.; Indelli, M. T.; Kleverlaan, C. J .; Alessio, E.;
Scandola, F. Coord. Chem. Rev. 2002, 229, 51. (d) Chichak, K.; Branda,
N. R. Chem. Commun. 2000, 1211. (e) Mak, C. C.; Bampos, N.; Sanders,
J . K. M. Chem. Commun. 1999, 1085. (f) Maiya, B. G.; Bampos, N.;
Kumar, R. K.; Feeder, N.; Sanders, J . K. M. New J . Chem. 2001, 25,
797. (g) Araki, K.; De Souza Lima, S.; Winnischofer, H. An. Acad. Bras.
Cienc. 2000, 72, 27. (h) Chichak, K.; Branda, N. R. Chem. Commun.
1999, 523. (i) Hamachi, I.; Tanaka, S.; Tsukiji, S.; Shinkai, S.; Oishi,
S. Inorg. Chem. 1998, 37, 4380. (j) Araki, K.; Toma, H. E. J . Coord.
Chem. 1993, 30, 9. (k) Collin, J .-P.; Dalbavie, J .-O.; Heitz, V.; Sauvage,
J .-P.; Flamigni, L.; Armaroli, N.; Balzani, V.; Barigelletti, F.; Mon-
tanari, I. Bull. Soc. Chim. Fr. 1996, 133, 749. (l) Flamigni, L.;
Barigelletti, F.; Armaroli, N.; Collin, J .-P.; Sauvage, J .-P.; Williams,
J . A. G. Chem. Eur. J . 1998, 4, 1744. (m) Campbell, K.; McDonald, R.;
Tykwinski, R. R. J . Org. Chem. 2002, 67, 1133. (n) Araki, K.; Losco,
P.; Engelmann, F. M.; Winnischofer, H.; Toma, H. E. J . Photochem.
Photobiol., A 2001, 142, 25. (o) Allwood, J . L.; Burrell, A. K.; Officer,
D. L.; Scott, S. M.; Wild, K. Y.; Gordon, K. C. Chem. Commun. 2000,
747. (p) Bruce, J . I.; Chambron, J . C.; Kolle, P.; Sauvage, J .-P. J . Chem.
Soc., Perkin Trans. 1 2002, 1226. (q) Alessio, E.; Ciani, E.; Iengo, E.;
Kukushkin, V. Y.; Marzilli, L. G. Inorg. Chem. 2000, 39, 1434.
(7) Iengo, E.; Minatel, R.; Milani, B.; Marzilli, L. G.; Alessio, E. Eur.
J . Inorg. Chem. 2001, 609.
(8) (a) Ribo, J . M.; Bofill, J . M.; Crusats, J .; Rubires, R. Chem. Eur.
J . 2001, 7, 2733. (b) Haycock, R. A.; Hunter, C. A.; J ames, D. A.;
Michelsen, U.; Sutton, L. R. Org. Lett. 2000, 2, 2435. (c) Kumar, R. K.;
Goldberg, I. Angew. Chem., Int. Ed. 1998, 37, 3027. (d) Ogawa, K.;
Kobuke, Y. Angew. Chem., Int. Ed. 2000, 112, 4236. (e) Kuroda, Y.;
Sugou, K.; Sasaki, K. J . Am. Chem. Soc. 2000, 122, 7833. (f) Hunter,
C. A.; Hyde, R. K. Angew. Chem., Int. Ed. Engl. 1996, 35, 1936. (g)
Burrell, A. K.; Officer, D. L.; Reid, D. C. W.; Wild, K. Y. Angew. Chem.,
Int. Ed. 1998, 37, 114. (h) Anderson, S.; Anderson, H. L.; Bashall, A.;
McPartlin, M.; Sanders, J . K. M. Angew. Chem., Int. Ed. Engl. 1995,
34, 1096. (i) Ambroise, A.; Li, J .; Yu, L.; Lindsey, J . S. Org. Lett. 2000,
2, 2563. (j) Twyman, L. J .; King, A. S. H. Chem. Commun. 2002, 910.
(k) Van der Boom, T.; Hayes, R. T.; Zhao, Y.; Bushard, P. J .; Weiss, E.
A.; Wasielewski, M. R. J . Am. Chem. Soc. 2002, 124, 9582. (l) Diskin-
Posner, Y.; Patra, G. K.; Goldberg, I. J . Chem. Soc., Dalton Trans. 2001,
2775. (m) Diskin-Posner, Y.; Patra, G. K.; Goldberg, I. Eur. J . Inorg.
Chem. 2001, 2515. (n) Diskin-Posner, Y.; Patra, G. K.; Goldberg, I.
Chem. Commun. 2002, 1420. (o) Ikeda, M.; Sugasaki, A.; Kubo, Y.;
Sugiyasu, K.; Takeuchi, M.; Shinkai, S. Chem. Lett. 2001, 1266. (p)
Otto, W. H.; Keefe, M. H.; Hupp, J .; Larive, C. K. Inorg. Chem. 2002,
41, 6172. (q) Hanks, T. W.; Bergman, B.; Dillon, P. Synth. Met. 2001,
121, 1431. (r) Hunter, C. A.; Tregonning, R. Tetrahedron 2002, 58, 691.
(s) Sugou, K.; Sasaki, K.; Kitajima, K.; Iwaki, T.; Kuroda, Y. J . Am.
Chem. Soc. 2002, 124, 1182. (t) Tamaru, S.-i.; Nakamura, M.; Takeuchi,
M.; Shinkai, S. Org. Lett. 2001, 3, 3631. (u) Yu, L.; Lindsey, J . S. J .
Org. Chem. 2001, 66, 7402. (v) Ogawa, K.; Zhang, T.; Yoshihara, K.;
Kobuke, Y. J . Am. Chem. Soc. 2002, 124, 22. (w) Cheng, K. F.; Drain,
C. M.; Grohmann, K. Inorg. Chem. 2003, 42, 2075. Zenkevich, E. I.;
Borczyskowski, C. V.; Shulga, A. M.; Bachilo, S.; Rempel, U.; Willert,
A. Chem. Phys. 2002, 275, 185. (x) Burrell, A. K.; J ones, B. M.; Hall,
S. B.; Officer, D. L.; Reid, D. C. W.; Wild, K. Y. J . Inclusion Phenom.
Macrocycl. Chem. 1999, 35, 185.
(9) (a) Ikeda, A.; Ayabe, M.; Shinkai, S.; Sakamoto, S.; Yamaguchi,
K. Org. Lett. 2000, 2, 3707. (b) Mackay, L. G.; Anderson, H. L.; Sanders,
J . K. M. Chem. Commun. 1992, 43. (c) Richeter, S.; J eandon, C.;
Gisselbrecht, J .-P.; Ruppert, R.; Callot, H. J . J . Am. Chem. Soc. 2002,
124, 6168. (d) Castriciano, M.; Romeo, A.; Romeo, R.; Scolaro, L. M.
Eur. J . Inorg. Chem. 2002, 531. (e) Richeter, S.; J eandon, C.; Ruppert,
R.; Callot, H. J . Chem. Commun. 2002, 266. (f) Onitsuka, K.; Kitajima,
H.; Fujimoto, M.; Iuchi, A.; Takei, F.; Takahashi, S. Chem. Commun.
2002, 2576. (g) Mackay, L. G.; Anderson, H. L.; Sanders, J . K. M. J .
Chem. Soc., Perkin Trans. 1 1995, 2269. (h) Sun, D.; Tham, F. S.; Reed,
C. A.; Chaker, L.; Boyd, P. D. W. J . Am. Chem. Soc. 2002, 124, 6604.
(i) Abrahams, B. F.; Hoskins, B. F.; Robson, R. J . Am. Chem. Soc. 1991,
113, 3606. (j) Brunner, H.; Schellerer, K.-M. Z. Naturforsch., B: Chem.
Sci. 2002, 751. (k) Schmitz, M.; Leininger, S.; Fan, J .; Arif, A. M.;
Stang, P. J . Organometallics 1999, 18, 4817.
(II) analogues are involved in the catalytic couplings of
meso-bromoporphyrins with simple terminal alkynes,
alkynylstannanes or alkynylzincs, and alkenyl organo-
metallics.25 It has been assumed in these examples that
the key step in the coupling reactions is the oxidative
addition of the meso-carbon-to-bromine bond to a
zerovalent palladium species, usually a bis(phosphine)
moiety. Several years ago, we serendipitously isolated
the resulting meso-η1-organopalladium(II) porphyrin
(16) (a) Chang, S. H.; Chung, K.-B.; Slone, R. V.; Hupp, J . Synth.
Met. 2001, 117, 215. (b) Aspley, C. J .; Lindsay Smith, J . R.; Perutz, R.
N. J . Chem. Soc., Dalton Trans. 1999, 2269. (c) Sharma, C. V. K.;
Broker, G. A.; Huddleston, J . G.; Baldwin, J . W.; Metzger, R. M.;
Rogers, R. D. J . Am. Chem. Soc. 1999, 121, 1137. (d) Kondo, M.;
Kimura, Y.; Wada, K.; Tadashi, M.; Ito, Y.; Kitagawa, S. Chem. Lett.
2000, 818. (e) Lo Schiavo, S.; Serroni, S.; Puntoriero, F.; Tresoldi, G.;
Piraino, P. Eur. J . Inorg. Chem. 2002, 79. (f) Benkstein, K. D.; Stern,
C. L.; Splan, K. E.; J ohnson, R. C.; Walters, K. A.; Vanhelmont, F. W.
M.; Hupp, J . Eur. J . Inorg. Chem. 2002, 2818. (g) Kumar, P. P.; Maiya,
B. G. New J . Chem. 2003, 27, 619. (h) Kim, H.-J .; Redman, J . E.;
Nakash, M.; Feeder, N.; Teat, S. J .; Sanders, J . K. M. Inorg. Chem.
1999, 38, 5178.
(17) Slone, R. V.; Hupp, J . Inorg. Chem. 1997, 36, 5422.
(18) (a) Guilard, R.; Tabard, A.; Van Caemelbecke, E.; Kadish, K.
M. The Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard,
R., Eds.; Academic Press: San Diego, CA, 2000; Vol. 3, p 295. (b)
Brothers, P. J . Adv. Organomet. Chem. 2001, 46, 223. (c) Tsutsui, M.
Pure Appl. Chem. 1978, 50, 735.
(19) (a) Schmidt, I.; Chmielewski, P. J . Chem. Commun. 2002, 92.
(b) Araki, K.; Winnischofer, H.; Toma, H. E.; Maeda, H.; Osuka, A.;
Furuta, H. Inorg. Chem. 2001, 40, 2020. (c) Furuta, H.; Kubo, N.;
Ishizuka, T.; Osuka, A.; Nanami, H.; Ogawa, T. Inorg. Chem. 2000,
39, 5424. (d) Furuta, H.; Ogawa, T.; Uwatoko, Y.; Araki, K. Inorg.
Chem. 1999, 38, 2676. (e) Chmielewski, P. J .; Latos-Grazynski, L.;
Schmidt, I. Inorg. Chem. 2000, 39, 5475. (f) Latos-Grazynski, L.;
Chmielewski, P. J . New J . Chem. 1997, 21, 691.
(10) Drain, C. M.; Lehn, J .-M. Chem. Commun. 1994, 2313.
(11) Drain, C. M.; Nifiatis, F.; Vasenko, A.; Batteas, J . D. Angew.
Chem., Int. Ed. Engl. 1998, 37, 2344.
(12) Fan, J .; Whiteford, J . A.; Olenyuk, B.; Levin, M. D.; Stang, P.
J .; Fleischer, E. B. J . Am. Chem. Soc. 1999, 121, 2741.
(13) Stang, P. J .; Fan, J .; Olenyuk, B. Chem. Commun. 1997, 1453.
(14) Kobayashi, N.; Muranaka, A.; Nemykin, V. N. Tetrahedron Lett.
2001, 42, 913.
(20) (a) Liu, D. C.; Lash, T. D. J . Org. Chem. 2003, 68, 1775.
Graham, S. R.; Colby, D. A.; Lash, T. D. Angew. Chem., Int. Ed. 2002,
41, 1371. (b) Richter, D. T.; Lash, T. D. Tetrahedron Lett. 1999, 40,
6735. (c) Richter, D. T.; Lash, T. D. Tetrahedron 2001, 57, 3657. (d)
Lash, T. D. Synlett 2000, 3, 279. Lash, T. D. Chem. Commun. 1998,
1683. (e) Lash, T. D.; Chaney, S. T. Angew. Chem., Int. Ed. 1997, 36,
8825. (f) Ghosh, A.; Wondimagegn, T.; Nilsen, H. J . J . Phys. Chem. B
1998, 102, 10459.
(15) Yuan, H.; Thomas, L.; Woo, L. K. Inorg. Chem. 1996, 35, 2808.

η1-Platinated Organometallic Porphyrins
Organometallics, Vol. 23, No. 3, 2004 393
Sch em e 1
from one of these reactions.24 Because such compounds
had not previously been studied in their own right, we
embarked on a systematic study of this type of pal-
ladium compound and have also studied their more
robust organoplatinum(II) analogues. Apart from our
reports, there appear to be no other examples of isolated
compounds with direct transition-metal to porphyrin
M-C σ-bonds. The present paper reports the results of
our recent work on (i) substitution reactions at the
Pt(II) by various nucleophiles and (ii) coordination for
the first time of these Pt(II) centers to various pyridyl
moieties. Investigation of this pyridine coordination has
allowed us to prepare and characterize several novel
self-assembled multiporphyrin arrays using the direct
porphyrin-platinum bond as a new construction prin-
ciple.
tion was the readily synthesized 2, and its transforma-
tions are shown in Scheme 1. This haloporphyrin is
easily prepared from the diarylporphyrin (Ar ) 3′,5′-
di-tert-butylphenyl) via a simple phenylation, bromina-
tion, metalation scheme in multigram quantities and
in high yields (ca. 75% over three steps from 3).23,26 One
of the major advantages stemming from the use of this
building block is that it is very soluble in many common
organic solvents (CHCl3, CH2Cl2, THF, DMSO, acetone,
ether, toluene, benzene; partly soluble in cyclohexane).
The inherent solubility of this macrocycle avoids the
problems that have plagued other multiporphyrin ar-
rays with3,7,10,12,13,15,17 and without2,27,28 coordinating
metal centers. The η1-organometallic porphyrin 4 has
been previously prepared by the oxidative addition of
the zerovalent platinum complex Pt(PPh3)3 to the ap-
propriate bromoporphyrin 2 in degassed toluene at 105
°C.23 It has since been found that a more attractive way
Resu lts a n d Discu ssion
Syn th eses of P or p h yr in Sta r tin g Ma ter ia ls. The
base porphyrin chromophore chosen for this investiga-
(21) (a) Hyslop, A. G.; Kellett, M. A.; Iovine, P. M.; Therien, M. J .
J . Am. Chem. Soc. 1998, 120, 12676. (b) Therien, M. J .; Deluca, M.;
International Pat. WO 02/104072 A2. (c) Bonomo, L.; Solari, E.; Martin,
G.; Scopelliti, R.; Floriani, C. Chem. Commun. 1999, 2319. (d) Sugiura,
K.-i.; Matsumoto, T.; Ohkouchi, S.; Naitoh, Y.; Kawai, T.; Takai, Y.;
Ushiroda, K.; Sakata, Y. Chem. Commun. 1999, 1957. (e) Dailey, K.
K.; Rauchfuss, T. B. Polyhedron 1997, 16, 3129. (f) Contakes, S. M.;
Beatty, S. T.; Dailey, K. K.; Rauchfuss, T. B.; Fenske, D. Organome-
tallics 2000, 19, 4767. (g) Smith, K. M.; Langry, K. C.; Minnetian, O.
M. J . Org. Chem. 1984, 49, 4602. (h) Morris, I. K.; Snow, K. M.; Smith,
N. W.; Smith, K. M. J . Org. Chem. 1990, 55, 1231. (i) Minnetian, O.
M.; Morris, I. K.; Snow, K. M.; Smith, K. M. J . Org. Chem. 1989, 54,
5567. (j) Buchler, J . W.; Herget, G. Z. Naturforsch., B: Chem. Sci. 1987,
42, 1003.
(22) (a) Hodgson, M. J .; Healy, P. C.; Williams, M. L.; Arnold, D. P.
J . Chem. Soc., Dalton Trans. 2002, 4497. (b) Arnold, D. P.; Healy, P.
C.; Hodgson, M. J .; Williams, M. L. J . Organomet. Chem. 2000, 607,
41.
(23) Hartnell, R. D.; Edwards, A. J .; Arnold, D. P. J . Porphyrins
Phthalocyanines 2002, 6, 695.
29
of preparing such platinioporphyrins is to use Pt(dba)2
(dba ) dibenzylideneacetone) in combination with tri-
phenylphosphine to generate the desired zerovalent
platinum complex in situ. The very reactive Pt(PPh3)2
(24) Arnold, D. P.; Sakata, Y.; Sugiura, K.-i.; Worthington, E. I.
Chem. Commun, 1998, 2331.
(25) (a) Lin, V. S. Y.; DiMagno, S. G.; Therien, M. J . Science 1994,
264, 1105. (b) DiMagno, S. G.; Lin, V. S. Y.; Therien, M. J . J . Org.
Chem. 1993, 58, 5983. (c) DiMagno, S. G.; Lin, V. S. Y.; Therien, M. J .
J . Am. Chem. Soc. 1993, 115, 2513. (d) Arnold, D. P.; Bott, R. C.;
Eldridge, H.; Elms, F. M.; Smith, G.; Zojaji, M. Aust. J . Chem. 1997,
50, 495. (e) Shanmugathasan, S.; J ohnson, C. K.; Edwards, C.;
Matthews, E. K.; Dolphin, D.; Boyle, R. W. J . Porphyrins Phthalocya-
nines 2000, 4, 228. (f) Taylor, P. N.; Huuskonen, J .; Rumbles, G.; Aplin,
R. T.; Williams, E.; Anderson, H. L. Chem. Commun. 1998, 909. (g)
Shultz, D. A.; Gwaltney, K. P.; Lee, H. J . Org. Chem. 1998, 63, 4034.
(h) Sugiura, K.-i.; Fujimoto, Y.; Sakata, Y. Chem. Commun. 2000, 1105.
(26) (a) Senge, M. O.; Feng, X. Tetrahedron Lett. 1999, 40, 4165. (b)
Senge, M. O.; Feng, X. J . Chem. Soc., Perkin Trans. 1 2000, 3615. (c)
Senge, M. O.; Kalisch, W. W.; Bischoff, I. Chem. Eur. J . 2000, 6, 2721.
(d) Feng, X.; Bischoff, I.; Senge, M. O. J . Org. Chem. 2001, 66, 8693.
(27) Arnold, D. P.; Heath, G. A.; J ames, D. A. J . Porphyrins
Phthalocyanines 1999, 3, 5.
(28) (a) Aratani, N.; Tsuda, A.; Osuka, A. Synlett 2001, 11, 1663.
(b) Tsuda, A.; Furuta, H.; Osuka, A. J . Am. Chem. Soc. 2001, 123,
10304.
(29) Cherwinski, W. J .; J ohnson, B. F. G.; Lewis, J . J . Chem. Soc.,
Dalton Trans. 1974, 1405.

394 Organometallics, Vol. 23, No. 3, 2004
Hartnell and Arnold
or Pt(dba)(PPh3)2 then undergoes oxidative addition
with the haloporphyrin. The initial product of the
oxidative addition is the cis isomer, which with contin-
ued heating slowly isomerizes (over ca. 6 h) to furnish
the desired trans isomer in a high yield. This method
has the distinct advantage over the previous method in
that it avoids the use of air-sensitive Pt(PPh3)3, which
if not freshly prepared may be of unknown or dubious
quality. The platinum-functionalized porphyrin 4 is an
air- and moisture-stable entity, in line with other η1-
organometallic platinio- and palladioporphyrins. How-
ever, some Br/Cl exchange is known to occur in chlori-
nated solvents.22-24
Bromide abstraction with silver nitrate in acetone/
CH2Cl2 proceeded smoothly to give the platinum nitrate
6 in 95% yield. The reaction was easily followed by TLC,
and the product was isolated by filtration to remove the
silver bromide byproduct, and the residue was washed
with water to remove excess silver nitrate. The platin-
ionitrate 6 was also found to be very soluble in common
organic solvents and is air- and moisture-stable. More-
over, the compound is stable in solution for several
weeks, with no detectable NO3/Cl exchange (as mea-
sured by 1H NMR) when dissolved in chlorinated
solvents, and stable for over one year in the solid state.
This complex was fully characterized, as outlined in the
Experimental Section, by 1H and 31P NMR, UV-visible
spectroscopy, high-resolution ESI mass spectrometry,
and elemental analysis. Understandably, the proton
NMR of 6 is similar to that of its parent compound;
however, small (ca. 0.2 ppm) upfield shifts are seen for
the porphyrin â-protons nearest the organometallic
fragment (i.e. 2,3,7,8-â-H). The 31P NMR of 6 shows no
change of the chemical shift of the equivalent tri-
phenylphosphine groups when compared to 4, indicating
similar polarity of the Pt-Br and Pt-ONO2 bonds. The
high-resolution ESI mass spectrum of 6 (calibrated
against an internal standard of NaI clusters) shows a
peak at m/z 1622.5124, which corresponds to the sodium
adduct of [M]+ (calculated m/z 1622.5034). Similarly,
another cluster is seen at m/z 1537.5221 corresponding
to the organometallic fragment after the loss of nitrate,
[M - NO3]+.
reaction of 4 in benzene, rather than dichloromethane,
where the redox potential of the system is apparently
low enough to avoid porphyrin oxidation and hence
achieve the anion exchange reaction. The simple workup
of filtering off the silver bromide byproduct and washing
the porphyrin residue with water furnished the desired
triflate-exchanged product 7 in an almost quantitative
yield. Inspection of the 1H and 31P NMR spectra of 7
showed that, unless the sample was rigorously dried
under high vacuum, it preferred to exist as the cationic
platinum complex with a water molecule as the coor-
dinated ligand. This gave rise to broadened peaks in
both the 1H and 31P NMR spectra. The coordinated
water peak can be seen at approximately 5.5 ppm as a
slightly broadened singlet. The identity of this peak was
confirmed by the addition of 1-2 µL of D2O to the NMR
sample, after which the singlet at 5.5 ppm further
broadened, diminished in size, and moved upfield to
about 4.7 ppm. Even in the most thoroughly dried sam-
1
ple the aqua species can be seen in the H NMR spec-
trum in approximately a 1:3 ratio with the triflato prod-
uct. The 31P NMR spectrum of 7 demonstrates the effect
of the bonded triflate on the equivalent neighboring
triphenylphosphine groups in 7. The phosphine reso-
nance occurs at 18.2 ppm (flanked by 195Pt satellites,
1J (31P-195Pt) ) 2958 Hz), considerably upfield of the
analogous resonance in the parent compound 4 that
occurs at 23.0 ppm. The high-resolution ESI mass spec-
trum supports the assigned structure and mainly con-
sists of the parent ion of 7 at m/z 1686.4776 (calculated
m/z 1686.4776) and [M - OTf]+ at m/z 1537.5234.
Self-Assem bly w ith P yr id yl Moieties. With the η1-
organometallic platinioporphyrin tectons 6 and 7 in
hand, the coordination of pyridines was investigated
(Scheme 2). This was initially attempted with the parent
platinioporphyrin bromide 4 in CHCl3 and pyridine. It
was found that even after stirring at elevated temper-
atures with an excess of pyridine the desired cationic
platinum complex was not formed. The reaction was
repeated with the nitratoplatinum complex 6 with a
stoichiometric amount of pyridine. It was found that
elevated temperatures were also required for this reac-
1
tion. Under these conditions, it was seen by both H and
It was also of interest to prepare the triflato platin-
ioporphyrin, due to the more electrophilic nature of the
Pt center. Initially, it was found that treatment of 4 with
silver triflate in dichloromethane led to the rapid
decomposition of the organometallic species and forma-
tion of a green product. Decomposition of the organo-
metallic species was also encountered by Stang et al.30
in studying their anthracene “molecular clip” system.
This observation is in line with the recent work of Osuka
and co-workers in their preparation of meso-meso
linked porphyrin arrays by Ag(I) oxidation of the por-
phyrin macrocycle.28,31 From this it can be seen that the
higher redox potential of Ag+ in dichloromethane (+0.65
V vs SCE)32 favors oxidation of the porphyrin macro-
cycle, rather than inducing metathesis. This problem
was overcome by carrying out the bromide abstraction
31P NMR that the desired cationic platinum complex
with coordinated pyridine was contaminated with the
NO3/Cl-exchanged product 5. To avoid the use of chlo-
rinated solvents, the reaction was repeated in acetone
at 50 °C with a stoichiometric amount of pyridine. The
1
reaction progress was monitored by H NMR, and the
conversion progressed smoothly and was considered
complete after approximately 5 h. The product 8a was
obtained as the hexafluorophosphate salt by the addi-
tion of an excess of KPF6. This procedure was repeated
1
with /2 equiv of 4,4′-bipyridine to furnish the bipyridine-
linked dimer 9a , which too was formed almost quanti-
tatively. It was also found that, with the more electro-
philic platinum triflate tecton 7, the reactions with both
pyridine (to form 8b) and 4,4′-bipyridine (to form 9b)
proceeded smoothly and were complete within 3 h at
room temperature (as monitored by 1H NMR). The
products did not require treatment with KPF6, as they
were quite stable as the triflate salts. This allowed the
use of chlorinated solvents for these simple self-as-
sembly reactions as the reaction proceeded relatively
(30) Kuehl, C. J .; Huang, S. D.; Stang, P. J . J . Am. Chem. Soc. 2001,
123, 9634.
(31) (a) Aratani, N.; Osuka, A. Bull. Chem. Soc. J pn. 2001, 74, 1361.
(b) Osuka, A.; Shimidzu, H. Angew. Chem., Int. Ed. 1997, 36, 135. (c)
Nakano, A.; Osuka, A.; Yamazaki, I.; Yamazaki, T.; Nishimura, Y.
Angew. Chem., Int. Ed. Engl. 1998, 37, 3023.
(32) Connelly, N. G.; Geier, W. E. Chem. Rev. 1996, 96, 877.

η1-Platinated Organometallic Porphyrins
Organometallics, Vol. 23, No. 3, 2004 395
Sch em e 2
quickly (ca. 3 h) at room temperature, thus avoiding
complications from the production of the triflate/chloro-
exchanged product 5.
the respective signals of the free ligand, supporting the
assigned structure. The resonances arising from the
porphyrin â-hydrogens nearest the organometallic frag-
ment (2,3,7,8-â-H’s) are understandably affected most
by the presence of a cationic platinum moiety. These
signals are shifted downfield from that of triflate 7 by
approximately 0.3-0.4 ppm. The triphenylphosphine
signals (6.8-7.0 ppm) also experience a slight upfield
shift after coordination of a pyridyl moiety. The sym-
metry of compounds 8b and 9b is also reflected in the
corresponding 31P NMR spectra, which consist of a
single resonance at approximately 19 ppm that is
NMR spectroscopy (1H and 31P) provides a convenient
means of characterizing these products. The resonances
of the pyridine and 4,4′-bipyridine moieties are all
shifted from the usual positions of the free ligands,
indicating that the desired coordination to the metal
center has occurred. The spectrum of 8b displays
resonances from the ortho protons of the pyridine ring
(Ho-py) as a broad doublet at 8.54 ppm (J ) 5.1 Hz),
indicating that they are equivalent and have shifted
upfield. Other signals arising from the pyridine moiety
are found as multiplets at 6.95 and 7.36 ppm, corre-
sponding to the m- (Hm-py) and p-pyridyl (Hp-py)
protons, respectively. These two resonances too are
shifted upfield from corresponding resonances in the
free ligand, supporting the conclusion of coordination
to platinum. Usually the resonances arising from the
pyridyl moiety are shifted somewhat downfield after
coordination to a cationic metal center;10,15,30,33 however,
these systems are usually lacking coordinated phos-
phine groups or utilize less sterically demanding and
magnetically isotropic trialkylphosphines. This effect
was demonstrated by Stang and co-workers33 by the
synthesis and comparison of self-assembled phosphine-
coordinated Pt and Pd cationic molecular squares with
either Et3P or dppp (1,3-bis(diphenylphosphino)propane)
ligands. It has been proposed in this example and
others12-14,33 that the significant shielding effects of the
bulky phenylphosphine groups offset the effect of the
cationic metal center to give an overall moderate upfield
shift of the pyridyl resonances. These assignments are
supported by significant cross-peaks in DQF-COSY
NMR experiments. Inspection of the 1H NMR spectrum
of the bipyridine-linked dimer 9b suggests a structure
with high symmetry. The bridging 4,4′-bipyridine group
is seen as a pair of coupled resonances (J ) 6.2 Hz) at
8.55 and 7.36 ppm, indicative of the bipyridyl ortho and
meta protons, respectively. The symmetry of this 4,4′-
bipyridine group demonstrates that the proposed di-
nuclear array 9b exists as the exclusive coordinated
species in solution. These 4,4′-bipyridine resonances are
also significantly shifted upfield by 0.3-0.4 ppm from
flanked by 195Pt satellites with
a corresponding
195Pt-31P coupling constant of about 2900 Hz. This
coupling constant is slightly diminished from that of
noncationic η1-organometallic platinioporphyrins by
about 50-100 Hz, reflecting the different cis influences
of pyridine and bromide.22-24
The ESI high-resolution mass spectra of the cationic
complexes 8b and 9b gave excellent agreement with the
predicted isotopic patterns. The mass spectrum of 8b
displayed a strong peak at m/z 1616.5786 corresponding
to the cationic fragment, [M - OTf]+ (calculated m/z
1616.5681). The bipyridine-bridged dimer 9b also dis-
played a significant cluster at m/z 1616.0803, which
corresponds well with the calculated pattern for the
dication after loss of both the triflate anions, namely
[M - 2OTf]2+ (calculated m/z 1616.0603). This cluster
displayed a line separation of half a mass unit in the
isotopic pattern, demonstrating that it is indeed the
dication that is being detected.
Self-Assem bly of Mu ltip or p h yr in Ar r a ys. With a
basic methodology for the coordination of pyridyl moi-
eties to η1-organometallic meso-platinioporphyrins es-
tablished, we wished to extend this to incorporate coor-
dination to a range of pyridylporphyrins (see Scheme
3). When triflate 7 was reacted with 1 equiv of 5-(4-
pyridyl)-10,15,20-tri-p-tolylporphyrin (10) in CDCl3 at
room temperature, formation of the new species 11 was
1
observed by H NMR. Likewise, the bis(pyridyl)porphy-
rin 12 and tetrakis(pyridyl)porphyrin 14, when reacted
with respective stoichiometric amounts of 7 (CDCl3,
room temperature, 5-24 h), gave rise to multi-
porphyrin arrays 13 and 15, respectively. From the 31P
and 1H NMR spectra of 11, 13, and 15 it was clearly
evident that the reactions were quite selective, with only
(33) Stang, P. J .; Cao, D. H.; Saito, S.; Arif, A. M. J . Am. Chem.
Soc. 1995, 117, 6273.

396 Organometallics, Vol. 23, No. 3, 2004
Hartnell and Arnold
Sch em e 3
one new species being produced in each case. The 31P
NMR spectra of these multiporphyrin arrays supported
the assigned structures and showed a single resonance
at around 20 ppm flanked by 195Pt satellites with a
1J Pt-P coupling constant of approximately 2900 Hz. Peak
shifts seen in the 1H NMR spectra of 11, 13, and 15
indicate moderate changes to the pyridine-appended
porphyrins after coordination to the η1-platinioporphy-
rins. These changes include upfield shifts of approxi-
mately 0.2 ppm of the o-pyridyl protons closest to the
coordinating metal centers of 11, 13, and 15. This
suggests moderate shielding from nearby triphenylphos-
phine groups. On the other hand, the m-pyridyl protons,
those closest to the porphyrin macrocycle, underwent
substantial downfield shifts (ca. 0.3 ppm) compared to
the parent porphyrin due to coordination of the pyridyl
group to a metal. These shifts of pyridyl o- and m-H
are in line with those previously reported for self-
assembled arrays and squares that contain coordinating
metal centers in conjunction with porphyrin macro-
cycles.10,12,15,17
The 1H NMR spectrum of 15 is, at first sight, not very
informative, because it displays broadened peaks for all
of the resonances. This is most likely to the slow rotation
of the macrocycles relative to each other in this large
array comprising bulky ligands. Despite the unattrac-
tive appearance of the 1D spectrum, the connectivity of
the newly formed array was demonstrated by 2D NMR
experiments (DQF-COSY and NOESY) (see the Sup-
porting Information). For example, the COSY experi-
ment showed the integrity of the Ni(II) and free base
porphyrin portions and showed that the 2,8-â-H signal
lies upfield of that for the remote 12,13,17,18-â-H’s. In
this pentanuclear array, the â-H’s of the central free
base pyridyl porphyrin are seen as a single resonance
at 8.60 ppm, indicative of a highly symmetrical struc-
ture. The NOESY spectrum indicated the connection of
the core with the peripheral porphyrins through the Pt
linker by the presence of strong nOe’s between the
pyridyl protons of the central free base porphyrin
macrocycle and the protons of the triphenylphosphine
groups on the metalated porphyrin (Figure 1). The

η1-Platinated Organometallic Porphyrins
Organometallics, Vol. 23, No. 3, 2004 397
F igu r e 1. Through-space correlations revealed by the
NOESY spectrum of pentanuclear array 15.
F igu r e 3. Absorption spectrum of 13 in CH2Cl2.
metric techniques. All mass spectra of 15 displayed the
singly charged fragment assignable to the individual
porphyrin macrocycle with the platinum phosphine
fragment attached at m/z 1537.2 (calculated m/z 1537),
indicating that considerable fragmentation of the mol-
ecule occurs under all these conditions. Elemental
analyses returned carbon percentages that are about 1%
low, which fits a solvate containing one molecule of
chloroform from the recrystallization solvent. The pres-
ence of the one proton from this solvent is difficult to
detect under the large, broad phosphine phenyl signal.
However, the formulation of this array as 15 is strongly
supported by the NMR spectra. Unfortunately, we have
so far been unable to grow crystals suitable for X-ray
analysis for any of these arrays, perhaps as a conse-
quence of using the solubilizing tert-butyl groups on the
peripheral aryl substituents.
Electr on ic Absor p tion Sp ectr a . The electronic
absorption spectra of the η1-organometallic platiniopor-
phyrins display some changes after coordination with
the various pyridyl moieties. The Soret band of the Ni-
(II) porphyrin (ca. 430 nm) is slightly red-shifted by
approximately 1-5 nm after coordination to the pyri-
dine fragment. Larger shifts are seen from the com-
plexes that involve coordination to free-base pyridyl
porphyrins i.e. complexes 11, 13, and 15. There is a
decrease in the extinction coefficient per porphyrin (or
per Ni(II) porphyrin) for these arrays. This suggests that
there is some through-space electronic coupling between
the porphyrin chromophores. However, the platinum
fragment acts more as a structural component than a
conjugative linking group. These observations are in line
with those of other groups.11-15 The coordinated free
base pyridyl porphyrins show moderate changes in their
electronic absorption spectra after coordination to plati-
num centers. The bands stemming from the free base
porphyrins that are visible and not overlapped by those
of the Ni(II) η1-organometallic platinioporphyrins show
larger 8-12 nm red shifts. The largest of these shifts is
seen in the Q band (IV) at highest energy for complexes
11 and 13. The spectrum of 13 is shown in Figure 3.
However, in pentanuclear array 15 band IV was ob-
scured by those of the Ni(II) porphyrins.
F igu r e 2. Experimental high-resolution ESI (bottom) and
predicted (top) mass spectral patterns for the ion [M -
2OTf]2+ for trinuclear array 13.
1
changes in H and 31P NMR spectra and nOe’s relating
the two types of macrocycles indicate that the desired
conjugate is indeed exclusively formed and that it is not
just a stoichiometric mixture of the individual tectons.
For all three complexes 11, 13, and 15, the inner NH
protons appear as single broad resonances at ap-
proximately -3 ppm, indicating that these arrays
comprise a single structure in solution and that the free
base porphyrin is intact.
Arrays 11 and 13 displayed high-resolution positive
ion mass spectra that agreed extremely well with those
predicted for the assigned structures. Both of these mass
spectra show strong parent ion peaks, which correspond
to the mass of the array after the loss of the triflate
counterions. For example, 13 displayed a strong peak
at m/z 1860.6544 ([M - 2OTf]2+), the cluster abundances
corresponding well with the calculated isotopic pattern
and the most intense ion matching at m/z 1860.6576
(Figure 2). This isotopic pattern of 13 displayed the
desired half mass unit separation between neighboring
peaks, indicating that it is indeed the assigned dication
that is being detected. Unfortunately, no peaks that
were assignable to the molecular ion of pentad 15 were
detected by ESI, FAB, or MALDI-TOF mass spectro-
Con clu sion
This report demonstrates that η1-organometallic pla-
tinioporphyrins may be incorporated into multiporphy-
rin arrays and that predetermined structural charac-
teristics of the individual tectons may be used to control

398 Organometallics, Vol. 23, No. 3, 2004
Hartnell and Arnold
dichloromethane and diluted with either dichloromethane/
methanol (1:1) or methanol, and solutions were introduced into
the source by direct infusion (syringe pump) at 60 µL/h, with
a capillary voltage of 80 V. The instrument was calibrated
using internal NaI. Positive ion FAB mass spectra were
recorded on a Kratos Concept instrument at the Central
Science Laboratory, University of Tasmania. Samples were
dissolved in dichloromethane and dispersed in a 4-nitrobenzyl
alcohol matrix. In the data below, masses given are for the
strongest observed peak in the molecular ion cluster. The
Microanalytical Service, The University of Queensland, pro-
vided the elemental analyses.
tr a n s-[P tBr (NiDAP P )(P P h 3)2] (4). Toluene (250 cm3) was
added to a Schlenk flask and degassed by bubbling argon
through the solution at 90 °C. Bromoporphyrin 2 (300 mg, 0.33
mmol) was added, and the mixture was stirred for 5 min. Pt-
(dba)2 (328 mg, 0.50 mmol) and triphenylphosphine (262 mg,
1.0 mmol) were added, and the solution was stirred at 90 °C
for 6 h. The residue after removal of the solvent (now air
stable) was purified by column chromatography, with 50%
CHCl3/hexane as eluent, and the residue from the major red
fraction was recrystallized from CHCl3/hexane to give 4 (460
mg, 85%) as dark red crystals. The spectroscopic data (1H and
31P NMR) of this compound agreed well with those of a sample
prepared previously using Pt(PPh3)3.23
the architecture of the newly self-assembled multicom-
ponent systems. These meso organometallic porphyrins
form stable conjugates with various pyridine ligands
and pyridyl-substituted porphyrins that are very stable
in solution for extended periods and in the solid state
indefinitely. These conjugates self-assemble selectively
in high yields when the individual components are
reacted in stoichiometrically equivalent ratios. The
newly formed arrays are highly soluble in common
organic solvents, a property that stems from the use of
trisubstituted parent monomers, and this avoids solu-
bility problems that have plagued other similar as-
semblies. High-resolution mass spectral data and single-
and multidimensional NMR experiments have unam-
biguously established their structures in solution. This
fundamental design approach will allow for the possible
incorporation of a large number of versatile components
tailored to the specific requirements of the assembly.
Various attractive components such as different met-
alloporphyrins and various electron-donor or -acceptor
fragments may be included as either substituents on a
η1-organometallic platinioporphyrin or as the pyridine-
substituted moiety, which is directly coordinated to an
organometallic porphyrin. The ability to tailor the
surface properties by the use of other substituents on
the aryl rings and alternative phosphine or other
ligands on the Pt(II) cationic center is an advantage.
This methodology should make it possible to attach
individual porphyrin macrocycles to surfaces via the
appropriately substituted pyridyl ligand in combination
with an organometallic porphyrin. For example, a η1-
organometallic platinioporphyrin coordinated to an
isonicotinic fragment will allow for attachment to a
nanoporous, nanocrystalline TiO2 film. Preparation of
these and other supramolecular assemblies that utilize
bis(meso-η1-organometallic)porphyrins and studies of
their electrochemical and photophysical properties are
in progress.
tr a n s-[P t(NO3)(NiDAP P )(P P h 3)2] (6). To a solution of
platinioporphyrin 4 (200 mg, 0.12 mmol) dissolved in CH2Cl2
(10 cm3) and acetone (50 cm3) was added silver nitrate (210
mg, 1.2 mmol). The solution was protected from light and
stirred at room temperature. After 3 h the reaction appeared
to be complete by TLC analysis (100% CH2Cl2), and the
solution was filtered through a fine glass frit to remove
suspended silver bromide and undissolved silver nitrate. The
solvent was removed in vacuo and the residue thoroughly
washed with water. After recrystallization from CH2Cl2/
pentane the product 6 (188 mg, 95%) was collected as bright
1
red crystals. H NMR (CDCl3, 400 MHz): δ 1.51 (s, 36H, tert-
butyl H on 10,20-aryl), 6.70-6.90 (m, 18H, PPh3), 6.90-7.00
(m, 12H, PPh3), 7.60-7.70 (m, 3H, m,p-H on 15-phenyl), 7.67
(t, 2H, J ) 1.8 Hz, 4′-H on 10,20-aryl), 7.71 (d, 4H, J ) 1.8
Hz, 2′,5′-H on 10,20-aryl), 7.95-8.05 (m, 2H, o-H on 15-phenyl),
8.10, 8.54, 8.57, 9.47 (each d, 2H, J ) 4.7 Hz, â-H). 31P NMR
1
(CDCl3, 121.4 MHz): δ 22.1 (s, J
3064 Hz). UV-vis (λmax
Pt-P
(ꢀ/103 M-1 cm-1)): 429 (227), 537 (16.3), 571 sh (4.4) nm. High-
Exp er im en ta l Section
resolution ESI MS: [M + Na]+, accurate mass calculated for
Gen er al P r ocedu r es. Syntheses involving zerovalent metal
precursors were carried out in an atmosphere of high-purity
argon using conventional Schlenk techniques. Porphyrin start-
ing materials 5,15-bis(3′,5′-di-tert-butylphenyl)porphyrin (3),34
5-bromo-10,20-bis(3′,5′-di-tert-butylphenyl)-15-phenylporphy-
rin (2),23 5-(4-pyridyl)-10,15,20-tri-p-tolylporphyrin (10), and
5,15-bis(4-pyridyl)-10,20-di-p-tolylporphyrin (12)15 and the
C
90H85N5NiO3P2PtNa (+1), 1622.5034; found, 1622.5124. Anal.
Calcd for C90H85N5NiO3P2Pt: C, 67.54, H, 5.35; N, 4.38.
Found: C, 67.60; H, 5.41; N, 4.30%.
tr a n s-[P t(OTf)(NiDAP P )(P P h 3)2] (7). Silver triflate (158
mg, 0.6 mmol) was added to a solution of platinum bromide 4
(200 mg, 0.12 mmol) in benzene (50 cm3). The reaction mixture
was stirred at room temperature for 5 h with protection from
light. Silver bromide was removed by filtration, and the residue
after solvent removal was washed thoroughly with water and
dried in vacuo. After recrystallization from CH2Cl2/pentane,
the product 7 was collected as a red solid (208 mg) in
quantitative yield. 1H NMR (CDCl3, 400 MHz): δ 1.47 (s, 36H,
tert-butyl H on 10,20-aryl), 6.70-6.80 (m, 18H, PPh3), 7.10-
7.20 (m, 12H, PPh3), 7.60-7.70 (m, 3H, m,p-H on 15-phenyl),
7.68 (t, 2H, J ) 1.8 Hz, 4′-H on 10,20-aryl), 7.70 (d, 4H, J )
1.8 Hz, 2′,5′-H on 10,20-aryl), 7.95-8.05 (m, 2H, o-H on 15-
phenyl), 8.16, 8.54, 8.56, 9.36 (each d, 2H, J ) 4.7 Hz, â-H).
29
platinum precursor Pt(dba)2 were synthesized by literature
methods. All other reagents and ligands were used as received
from Sigma-Aldrich. Toluene was AR grade, stored over
sodium wire and degassed by heating and purging with argon
at 90 °C. All other solvents were AR grade, and dichlo-
romethane and chloroform were stored over anhydrous sodium
carbonate. Analytical TLC was performed using Merck silica
gel 60 F254 plates, and column chromatography was performed
using Merck silica gel (230-400 mesh). NMR spectra were
recorded on Bruker Avance 400 MHz or Varian Unity 300 MHz
instruments in CDCl3 solutions, using CHCl3 as the internal
1
31P NMR (CDCl3, 121.4 MHz): δ 18.2 (bs, J Pt-P ) 2958 Hz).
1
UV-vis (λmax (ꢀ/103 M-1 cm-1)): 429 (215), 537 (17.4), 568 (5.6)
nm. High-resolution ESI MS: [M]+, accurate mass calculated
for C91H85F3N4NiO3P2PtS (+1), 1686.4776; found, 1686.4204.
In solution, 7 was found to be in equilibrium with the
cationic aquated analogue, namely trans-[Pt(NiDAPP)(H2O)-
(PPh3)2](OTf), in an approximate 3:1 ratio, and 1H NMR
spectroscopic data of the latter are as follows. 1H NMR (CDCl3,
400 MHz): δ 1.47 (s, 36H, tert-butyl H on 10,20-aryl), 5.57 (s,
reference at 7.26 ppm for H spectra and external 85% H3PO4
as the reference for proton-decoupled 31P spectra. UV-visible
spectra were recorded on a Cary 3 spectrometer in dichlo-
romethane solutions. High-resolution ESI mass spectra were
recorded on a Bruker BioApex 47e FTMS fitted with an
Analytica electrospray source. The samples were dissolved in
(34) Manka, J . S.; Lawrence, D. S. Tetrahedron Lett. 1989, 30, 6989.

η1-Platinated Organometallic Porphyrins
Organometallics, Vol. 23, No. 3, 2004 399
2H, coordinated H2O) 6.80-6.90 (m, 18H, PPh3), 7.00-7.10
(m, 12H, PPh3), 7.60-7.70 (m, 3H, m,p-H on 15-phenyl), 7.68
(t, 2H, J ) 1.8 Hz, 4′-H on 10,20-aryl), 7.70 (d, 4H, J ) 1.8
Hz, 2′,5′-H on 10,20-aryl), 7.95-8.05 (m, 2H, o-H on 15-phenyl),
8.17, 8.52, 8.54, 9.52 (each d, 2H, J ) 4.7 Hz, â-H).
J ) 1.8 Hz, 4′-H on 10,20-aryl), 7.79 (d, 4H, J ) 1.8 Hz, 2′,5′-H
on 10,20-aryl), 7.84 (m, 2H, m-H on 5-pyridyl), 8.00-8.05 (m,
2H, o-H on 15-phenyl), 8.10 (m, 6H, o-H on 10,15,20-tolyl),
8.18, 8.60, 8.62, 8.65 (each overlapping d, 2H, J ) 4.7 Hz, â-H
on free base porphyrin), 9.27 (m, 2H, o-H on 5-pyridyl), 8.42,
8.62, 8.64, 9.90 (each d, 2H, J ) 4.7 Hz, â-H on Ni porphyrin).
Gen er a l P r oced u r e for th e P r ep a r a tion of Com p ou n d s
8b, 9b, 11, 13, a n d 15. To a solution of 7 (20.0 mg, 0.012 mmol)
in CDCl3 (3 cm3) was added a stoichiometric amount of the
pyridyl-containing ligand as a CDCl3 solution. The vessel was
sealed and stirred at room temperature. Afterward an aliquot
was removed via syringe and transferred to an NMR tube for
monitoring of the reaction progress by 1H and 31P NMR. Once
the reaction was considered complete (3-24 h), the NMR
sample was recombined with the bulk reaction sample and the
solvent removed in vacuo. The residue was recrystallized to
yield the appropriate cationic platinum complex as a red solid.
Where required, the product was recrystallized again as noted
and dried thoroughly under high vacuum at 80 °C in order to
obtain a sample for elemental analysis.
1
31P NMR (CDCl3, 121.4 MHz): δ 19.5 (s, J Pt-P ) 2907 Hz).
UV-vis (λmax (ꢀ/103 M-1 cm-1)): 430 (367), 453 sh (111), 522
sh (22.4), 536 (25.9), 587 (7.1), 647 (3.5) nm. High-resolution
ESI MS: [M - OTf]+, accurate mass calculated for C136H120N9-
NiP2Pt (+1), 2195.8170; found, 2195.8270.
{[tr a n s-P t(NiDAP P )(P P h 3)2]2(H2DP yDTP )}(OTf)2 (13).
Recrystallized from CHCl3/pentane, to give 13 (22 mg) in 89%
yield. 1H NMR (CDCl3, 400 MHz): δ -3.10 (bs, 2H, NH), 1.50
(s, 72H, tert-butyl H on 10,20-aryl), 2.72 (s, 6H, 4′-CH3 on
10,20-tolyl), 6.80-7.0 (m, 36H, PPh3), 7.10-7.20 (m, 24H,
PPh3), 7.64 (d, 4H, J ) 8.1 Hz, m-H on 10,20-tolyl), 7.67 (m,
6H, m,p-H on 15-phenyl), 7.73 (t, 4H, J ) 1.8 Hz, 4′-H on
10,20-aryl), 7.78 (d, 8H, J ) 1.8 Hz, 2′,5′,-H on 10,20-aryl),
7.85 (m, 4H, m-H on 5,15-pyridyl), 8.00-8.05 (m, 2H, o-H on
15-phenyl), 8.10 (d, 4H, J ) 8.1 Hz, o-H on 10,20-tolyl), 8.16,
8.88 (each d, 4H, J ) 4.7 Hz, â-H on free base porphyrin), 9.20
(d, 4H, o-H on 5,15-pyridyl), 8.42, 8.61, 8.63, 9.90 (each d, 2H,
J ) 4.7 Hz, â-H on Ni porphyrin). 31P NMR (CDCl3, 121.4
tr a n s-[P t(NiDAP P )(p y)(P P h 3)2](OTf) (8b). Recrystallized
from CH2Cl2/pentane, to give 8b (21 mg) in 97% yield. 1H NMR
(CDCl3, 400 MHz): δ 1.47 (s, 36H, tert-butyl H on 10,20-aryl),
6.70-6.90 (m, 18H, PPh3), 6.95 (m, 2H, m-H on pyridine (signal
overlapped by PPh3)), 6.90-7.00 (m, 12H, PPh3), 7.36 (m, 1H,
p-H on pyridine), 7.60-7.70 (m, 3H, m,p-H on 15-phenyl), 7.71
(t, 2H, J ) 1.8 Hz, 4′-H on 10,20-aryl), 7.75 (d, 4H, J ) 1.8
Hz, 2′,5′-H on 10,20-aryl), 7.95-8.05 (m, 2H, o-H on 15-phenyl),
8.54 (d, 2H, J ) 5.1 Hz, o-H on pyridine), 8.49, 8.58, 8.62, 9.70
1
MHz): δ 19.5 (s, J Pt-P ) 2895 Hz). UV-vis (λmax (ꢀ/103 M-1
cm-1)): 433 (601), 519 sh (34.4), 357 (43.3), 586 (13.5), 648
(7.3) nm. High-resolution ESI MS: [M - 2OTf]2+, accurate
mass calculated for
found, 1860.6544.
C201H202N14Ni2P4Pt2 (+2), 1860.6576;
(each d, 2H, J ) 4.7 Hz, â-H). 31P NMR (CDCl3, 121.4 MHz):
1
δ 19.2 (s, J Pt-P ) 2906 Hz); UV-vis: λmax (ꢀ/103 M-1 cm-1
)
{[tr a n s-P t(NiDAP P )(P P h 3)2]4(H2TP yP )}(OTf)4 (15). Re-
crystallized twice from CHCl3/cyclohexane, to give 15 (18 mg)
in 78% yield. 1H NMR (CDCl3, 400 MHz): δ -3.2 (bs, 2H, NH),
1.50 (s, 144H, tert-butyl H on 10,20-aryl), 6.75-7.10 (m, 48H,
PPh3), 7.10-7.30 (m, 72H, PPh3), 7.60-7.70 (m, 12H, m,p-H
on 15-phenyl), 7.78 (bs, 8H, 4′-H on 10,20-aryl), 7.82 (bs, 16H,
2′,5′-H on 10,20-aryl), 7.98 (bd, 8H, J ) 5.2 Hz, m-H on 5,10,-
15,20-pyridyl), 8.00-8.10 (m, 8H, o-H on 15-phenyl), 8.60 (bs,
8H, â-H on free base porphyrin (overlapped by â-H on Ni
porphyrin)), 9.48 (bd, 8H, J ) 5.2 Hz, o-H on 5,10,15,20-
pyridyl), 8.46, 8.61, 8.63 (overlapping), 9.92 (each d, 8H, J )
429 (197), 538 (15.6), 574 (3.8) nm; High-resolution ESI MS:
[M - OTf]+, accurate mass calculated for C95H90N5NiP2Pt (+1),
1616.5681; found, 1616.5786, Anal. Calcd for C96H90F3N5-
NiO3P2PtS: C, 65.27; H, 5.14; N, 3.96. Found: C, 65.00; H,
4.88; N, 4.02%.
{[tr a n s-P t (NiDAP P )(P P h 3)2]2(4,4′-b ip yr id in e)}(OTf)2
(9b). Recrystallized from CH2Cl2/pentane, to give 9b (19 mg)
in 93% yield. 1H NMR (CDCl3, 400 MHz): δ 1.48 (s, 72H, tert-
butyl H on 10,20-aryl), 6.70-6.90 (m, 36H, PPh3), 6.90-7.00
(m, 24H, PPh3), 7.36 (d, 4H, J ) 6.2 Hz, m-H on 4,4′-
bipyridine), 7.60-7.70 (m, 6H, m,p-H on 15-phenyl), 7.74 (t,
4H, J ) 1.8 Hz, 4′-H on 10,20-aryl), 7.78 (d, 8H, J ) 1.8 Hz,
2′,5′-H on 10,20-aryl), 7.95-8.05 (m, 4H, o-H on 15-phenyl),
8.55 (d, 4H, J ) 6.2 Hz, o-H on 4,4′-bipyridine), 8.40, 8.58,
8.63, 9.67 (each d, 4H, J ) 4.7 Hz, â-H). 31P NMR (CDCl3, 121.4
1
4.7 Hz, â-H). 31P NMR (CDCl3, 121.4 MHz): δ 20.3 (s, J Pt-P
) 2954 Hz). UV-vis (λmax (ꢀ/103 M-1 cm-1)): 434 (768), 538
(80.1), 587 sh (20.1), 646 (4.4) nm. FAB MS: [Pt(NiDAPP)-
(PPh3)2]+ fragment, 1537.2; mass calculated for most intense
peak of cluster C90H85N4NiP2Pt (+1), 1537.5. Anal. Calcd for
1
MHz): δ 18.9 (s, J Pt-P ) 2894 Hz). UV-vis (λmax (ꢀ/103 M-1
C404H366F12N24Ni4O12P8Pt4S4‚CHCl3: C, 64.95, H, 4.97; N, 4.49.
Found: C, 64.87; H, 4.85; N, 4.50.
cm-1)): 430 (387), 538 (35.4), 578 sh (9.4) nm. High-resolu-
tion ESI MS: [M - 2OTf]2+, accurate mass calculated for
C
190H178N10Ni2P4Pt2 (+2), 1616.0603; found, 1616.0803. Anal.
Ack n ow led gm en t. R.D.H. thanks the Faculty of
Science, Queensland University of Technology, for a
Post-Graduate Scholarship.
Calcd for C192H178F6N10Ni2O6P4Pt2S2: C, 65.31; H, 5.08; N,
3.97. Found: C, 65.04; H, 4.86; N, 3.93.
tr a n s-[P t(NiDAP P )(H2P yTTP )(P P h 3)2](OTf) (11). Re-
crystallized from CHCl3/pentane, to give 11 (26 mg) in 88%
yield. 1H NMR (CDCl3, 400 MHz): δ -2.80 (bs, 2H, NH), 1.47
(s, 36H, tert-butyl H on 10,20-aryl), 2.70 (s, 3H, 4′-CH3 on
15-tolyl), 2.80 (s, 6H, 4′-CH3 on 10,20-tolyl), 6.80-7.0 (m,
18H, PPh3), 7.15-7.30 (m, 12H, PPh3), 7.57 (m, 6H, m-H on
10,15,20-tolyl), 7.66 (m, 3H, m,p-H on 15-phenyl), 7.75 (t, 2H,
Su p p or tin g In for m a tion Ava ila ble: Figures giving 1D,
DQF-COSY, and NOESY 1H NMR spectra of the pentanuclear
array 15. This material is available free of charge via the
Internet at http://pubs.acs.org.
OM0305869