solitaire-Porphyrazines: Synthetic, structural, and spectroscopic investigation of complexes of the novel binucleating norphthalocyanine-2,3-dithiolato ligand

Article abstract of DOI:10.1021/ja9619115

We have developed the synthesis of unsymmetrical metalloporphyrazines of the form M[pz(A:B₃)], where A and B refer to two different types of peripheral functionality, and have used it to prepare new bi- and trimetallic solitaire-porphyrazines in which A represents a mono- or bimetallic moiety. The macrocyclic complexes described are based on the binucleating ligand, [M(norphthalocyanine-2,3-dithiolate)]^2-, [M(norpc)]^2-. This can be thought of as a metalloporphyrazine where B is a fused benzo ring; A represents two thiolates fused at the β-pyrrole positions to form a dithiolene moiety that can bind a transition-metal ion in addition to one within the macrocyclic cavity. solitaire-Porphyrazines have been synthesized by chelation of [(L-L)M']²⁺ to the [M(norpc)]^2- ligand where M = '2H', Ni, Cu, or Mn-Cl, L-L is a bis(diphosphino) or bis(diamino) group and M' = Ni, Pd, or Pt. Crystal structures have been obtained for 11b, where the [H₂(norpc)]^2- ligand coordinates the diphosphinopalladium moiety, [Pd(dppf)]²⁺, by the two thiolate sulfur atoms at its periphery, and for 11h, with the diaminoplatinum moiety, [Pt(teeda)]²⁺, bound to the periphery of the [Ni(norpc)]^2- ligand. In crystals 11b and 11h, the molecules appear as face-to-face dimers. However, the dimer of 11b and the two crystallographically independent dimers of 11h each shows a distinctly different degree of overlap. The electronic absorption spectra of a series of porphyrazines in which the two peripheral sulfur atoms form thioether moieties with a modified benzyl-protecting group (6-10) show that the peripheral asymmetry of the macrocyclic framework causes a strong splitting of the (π-π*) Q-band. In contrast, when the peripheral sulfurs bind a metal ion to form solitaire-porphyrazines 11a-h. the optical spectra closely resemble that of the symmetrical pc, with unsplit Q band. The EPR spectrum of solitaire 11d, where M = Cu, L-L = a bis(diphosphino) cap, M' = Pd, has features consistent with other square-planar copper(II) porphyrins and phthalocyanines. Cyclic voltammograms of compound 11b shows two reversible ring reductions at potentials similar to those of H₂(pc) as well as a reversible oxidation associated with the ferrocene portion of the Pd(dppf) moiety.

Full text of DOI:10.1021/ja9619115

J. Am. Chem. Soc. 1996, 118, 10479-10486
10479
solitaire-Porphyrazines: Synthetic, Structural, and
Spectroscopic Investigation of Complexes of the Novel
Binucleating Norphthalocyanine-2,3-dithiolato Ligand
Theodore F. Baumann,† Mohammad S. Nasir,† John W. Sibert,†
Andrew J. P. White,§ Marilyn M. Olmstead,‡ David J. Williams,§
Anthony G. M. Barrett,*,§ and Brian M. Hoffman*,†
Contribution from the Departments of Chemistry, Northwestern UniVersity,
EVanston, Illinois 60208, Imperial College of Science, Technology and Medicine,
South Kensington, London SW7 2AY, U.K., and UniVersity of California-DaVis,
DaVis, California 95616
ReceiVed June 7, 1996X
Abstract: We have developed the synthesis of unsymmetrical metalloporphyrazines of the form M[pz(A:B3)], where
A and B refer to two different types of peripheral functionality, and have used it to prepare new bi- and trimetallic
solitaire-porphyrazines in which A represents a mono- or bimetallic moiety. The macrocyclic complexes described
are based on the binucleating ligand, [M(norphthalocyanine-2,3-dithiolate)]2-, [M(norpc)]2-. This can be thought
of as a metalloporphyrazine where B is a fused benzo ring; A represents two thiolates fused at the â-pyrrole positions
to form a dithiolene moiety that can bind a transition-metal ion in addition to one within the macrocyclic cavity.
solitaire-Porphyrazines have been synthesized by chelation of [(L-L)M′]2+ to the [M(norpc)]2- ligand where M )
“2H”, Ni, Cu, or Mn-Cl, L-L is a bis(diphosphino) or bis(diamino) group and M′ ) Ni, Pd, or Pt. Crystal structures
have been obtained for 11b, where the [H2(norpc)]2- ligand coordinates the diphosphinopalladium moiety, [Pd-
(dppf)]2+, by the two thiolate sulfur atoms at its periphery, and for 11h, with the diaminoplatinum moiety, [Pt-
(teeda)]2+, bound to the periphery of the [Ni(norpc)]2- ligand. In crystals of 11b and 11h, the molecules appear as
face-to-face dimers. However, the dimer of 11b and the two crystallographically independent dimers of 11h each
shows a distinctly different degree of overlap. The electronic absorption spectra of a series of porphyrazines in
which the two peripheral sulfur atoms form thioether moieties with a modified benzyl-protecting group (6-10)
show that the peripheral asymmetry of the macrocyclic framework causes a strong splitting of the (π-π*) Q-band.
In contrast, when the peripheral sulfurs bind a metal ion to form solitaire-porphyrazines 11a-h, the optical spectra
closely resemble that of the symmetrical pc, with unsplit Q band. The EPR spectrum of solitaire 11d, where M )
Cu, L-L ) a bis(diphosphino) cap, M′ ) Pd, has features consistent with other square-planar copper(II) porphyrins
and phthalocyanines. Cyclic voltammograms of compound 11b shows two reversible ring reductions at potentials
similar to those of H2(pc) as well as a reversible oxidation associated with the ferrocene portion of the Pd(dppf)
moiety.
Introduction
phthalocyanines10 that have been functionalized with appendages
that can coordinate metal ions as well.
Coordination compounds prepared from ligand systems
capable of binding multiple metal ions are of importance in
studies of electron transfer,1 magnetic interactions,2 optical
phenomena,3 excited-state reactivity,4 biomimetic chemistry,5
mixed valency,6 and ionophoric activity.7 One strategy for the
design of multimetallic systems has involved the use of
polynucleating macrocyclic ligands,8 and, in particular, much
work has been devoted to the synthesis of porphyrins9 and
(5) (a) Goldberg, D. P.; Koulougliotis, D.; Brudvig, G. W.; Lippard, S.
J. J. Am. Chem. Soc. 1995, 117, 3134-3144. (b) Waton, S. P.; Masschelein,
A.; Liu, S.; Rebek, J., Jr.; Lippard, S. J. J. Am. Chem. Soc. 1994, 116,
5196-5205. (c) Karlin, K. D.; Nasir, M. S.; Cohen, B. I.; Cruse, R. W.;
Kaderli, S.; Zuberbuhler, A. D. J. Am. Chem. Soc. 1994, 116, 1324-1336.
(d) Sessler, J. L.; Sibert, J. W.; Lynch, V.; Markert, J. T.; Wooten, C. L.
Inorg. Chem. 1993, 32, 621-626.
(6) (a) Sharp, P. R.; Raymond, K. N.; Smart, J. C.; McKinney, R. J. J.
Am. Chem. Soc. 1981, 103, 753. (b) Morrison, W. H.; Hendrickson, D. N.
Inorg. Chem. 1975, 14, 2331. (c) Cowan, D. O.; Levanda, C. J. Am. Chem.
Soc. 1972, 94, 9271.
† Northwestern University.
§ Imperial College of Science, Technology, and Medicine.
‡ University of California-Davis.
(7) Gibney, B. R.; Kessissoglou, D. P.; Kampf, J. W.; Pecoraro, V. L.
Inorg. Chem. 1994, 33, 4840-4849.
X Abstract published in AdVance ACS Abstracts, October 1, 1996.
(1) (a) Che, C. M.; Butler, L. G.; Grunthaner, P. J.; Gray, H. B. Inorg.
Chem. 1985, 24, 4662. (b) Heuer, W. B.; Totten, M.; Rodman, G. S.;
Herbert, E. J.; Tracy, H. J.; Nagle, J. K. J. Am. Chem. Soc. 1984, 106,
1163.
(8) (a) Beer, P. D.; Drew, M. G. B.; Leeson, P. B.; Lyssenko, K.; Ogden,
M. I. J. Chem. Soc., Chem. Commun. 1995, 929-930. (b) Bazzicalupi,
C.; Bencini, A.; Bianchi, A.; Fusi, V.; Giorgi, C.; Paoletti, P.; Stefani, A.;
Valtancoli, B. Inorg. Chem. 1995, 34, 552-559. (c) Coucouvanis, D.;
Jonasdottir, S. G.; Christodoulou, D.; Kim, C. G.; Kampf, J. W. Inorg.
Chem. 1993, 32, 2987-2988. (d) Stumpf, H. O.; Pei, Y.; Kahn, O.; Sletten,
J.; Renard, J. P. J. Am. Chem. Soc. 1993, 115, 6738-6745. (e) Rockcliffe,
D. A.; Martell, A. E. Inorg. Chem. 1993, 32, 3143-3152.
(2) (a) Kahn, O. Molecular Magnetism; VCH Publishers, Inc.: New
York, 1993. (b) Gupta, G. P.; Lang, G.; Koch, C. A.; Wang, B.; Scheidt,
W. R.; Reed, C. A. Inorg. Chem. 1990, 29, 4234.
(3) (a) Barigelletti, F.; De Cola, L.; Balzani, V.; Hage, R.; Haasnoot, J.
G.; Reedijk, J.; Vos, J. G. Inorg. Chem. 1989, 28, 4344-4350. (b)
O’Halloran, T. V.; Roberts, M. M.; Lippard, S. J. Inorg. Chem. 1986, 25,
957.
(4) (a) Che, C. M.; Butler, L. G.; Gray, H. B. J. Am. Chem. Soc. 1981,
103, 7796. (b) Fordyce, W. A.; Brummer, J. G.; Crosby, G. A. J. Am.
Chem. Soc. 1981, 103, 7061.
(9) (a) Sessler, J. L.; Weghorn, S. J.; Hiseada, Y.; Lynch, V. Chem. Eur.
J. 1995, 1, 56-67. (b) Hamilton, A.; Lehn, J.-M.; Sessler, J. L. J. Am.
Chem. Soc. 1986, 108, 5158-5167. (c) Basu, P.; Raitsimring, A. M.;
LaBarre, M. J.; Dhawan, I. K.; Weibrecht, J. L.; Enemark, J. H. J. Am.
Chem. Soc. 1994, 116, 7166-7176. (d) Drain, C. M.; Lehn, J.-M. J. Chem.
Soc. Chem. Commun. 1994, 2313-2315. (e) Chang, C. K. J. Am. Chem.
Soc. 1977, 99, 2819-2822.
S0002-7863(96)01911-7 CCC: $12.00 © 1996 American Chemical Society

10480 J. Am. Chem. Soc., Vol. 118, No. 43, 1996
Baumann et al.
We have been developing the synthesis of peripherally
functionalized porphyrazines (tetraazaporphyrins), in part to
prepare new polynucleating ligands based on this planar ring
system.11 The first of the series was porphyrazineoctathiolate
Chart 1
1, (pzot)8-
. As a porphyrazine ring substituted with eight
thiolate sulfur atoms at the â-pyrrole positions, it can coordinate
four metal ions at the periphery in addition to one within the
macrocyclic cavity. This ligand was designed so that the metal
ions would exhibit bidentate (S-S) coordination as in dithiolene
complexes, leading to pentanuclear porphyrazines that exhibit
a high degree of electronic interaction between the peripheral
and central metal ions as mediated by the conjugated porphyra-
zine core. Interestingly, a second distinct coordination mode
was discovered in which two thiolate sulfur atoms from adjacent
pyrroles and one meso-nitrogen atom act as ligands from the
macrocycle. This tridentate (S-N-S) coordination of four
dialkyltin moieties to Ni(pzot)8-, 2, was the first example of
meso-coordination in a porphyrazine system.11 Utilization of
the bidentate (S-S) coordination sites of the octathiolate ligand
was achieved through the choice of a peripherally “capping”
metal ion complex that provided only two coordination sites in
the cis configuration. A series of symmetrical pentametallic
porphyrazine complexes12 were synthesized through the reaction
of M(pzot)8- and Ni(II)(P-P)X2, 3, where P-P is a chelating
cis-diphosphine, in which the four peripheral “dithiolene”
ligands are coordinated to the (P-P)Ni(II) moieties in the
bidentate mode.
Materials and Methods
Procedures. All starting materials were purchased from Aldrich
Chemical and used as received with the exceptions of (teeda)PtI215 and
Na2(mnt)16 which were prepared by the literature methods. THF and
CH2Cl2 were distilled from sodium/benzophenone ketyl and CaH2,
respectively; all other solvents were used as purchased without
additional purification. 1H and 13C NMR spectra were obtained using
a Gemini 300 spectrometer. Electronic absorption spectra were
recorded using a Hewlett-Packard HP8452A diode-array spectropho-
tometer. Cyclic voltammetry was done on a Cypress Systems 2000
electroanalytical system. Elemental analyses were performed by Searle
Laboratories, Skokie, IL and Onieda Research Services, Whitesboro,
NY and are included in supporting information (Table S11). Fast atom
bombardment mass spectra (FAB-MS) were recorded locally by Dr.
Doris Hung using a VG-70-250SE instrument. Electron paramagnetic
resonance (EPR) spectra were measured using a modified Varian E-4
X-band spectrometer, and the field was calibrated using diphenylpic-
rylhydrazyl (dpph) as a standard. Powder EPR samples of Cu(norpc)
(9) and solitaire-porphyrazine, [(dppf)Pd][Cu(norpc)] (11d), were
prepared by recrystallizing about 1% of each in their corresponding
diamagnetic metal-free hosts from CHCl3/MeOH.
n-Butyl(4-chloromethyl)benzoate (4). SOCl2(12 mL, 0.165 mol)
was added dropwise to a solution of 4-chloromethylbenzoic acid (25
g, 0.15 m) in DMF (25 mL). After addition was complete, the solution
was heated to 85 °C for 3 h. The DMF and excess SOCl2 were removed
under vacuum, and the acyl chloride was quenched with n-BuOH (11.1
g, 0.15 M) in dry CH2Cl2. Removal of the solvent yielded the product
as a clear oil (25.4 g, 75%); H NMR (CDCl3) δ (ppm) 8.0 (d, 2H),
7.40 (d, 2H), 4.55 (s, 2H), 4.15 (t, 2H), 1.75 (qn, 2H), 1.45 (sx, 2H),
0.95 (t, 3H); EI-MS 227.
Bis(4-(butyloxycarbonyl)benzyl)dithiomaleonitrile (5). A solution
of 4 (9.0 g, 0.04 M), Na2(mnt) (3.72 g, 0.02 mol), and NaI in acetone
was heated to reflux for 24 h. The solution was filtered hot, and the
acetone was removed by rotary evaporation. The residue was taken
up in CHCl2 and washed three times with water. The organic layer
was dried with Na2SO4, and the solvent was removed by rotary
evaporation to yield a red oil. The product was obtained as a white
solid after recrystallization from EtOH (14.6 g, 75%): mp 215-217
°C; 1H NMR (CDCl3) δ (ppm) 8.0 (d, 2H), 7.40 (d, 2H), 4.32 (s, 2H),
4.32 (t, 2H), 1.75 (qn, 2H), 1.45 (sx, 2H), 0.95 (t, 3H); 13C NMR
(CDCl3) δ (ppm) 165.93, 139.24, 130.53, 130.26, 129.04, 121.54, 65.01,
38.75, 30.65, 19.20, 13.72; FAB-MS 523 (M + H+).
In this and the following paper (J. Am. Chem. Soc. 1996,
118, 10487),13 we describe the synthesis of unsymmetrical
porphyrazines of the type, M[pz(An:B4-n)], where A and B refer
to two different types of peripheral functionality and n ) 1-3,
with a focus on the molecules in which A involves a metal-
chelating moiety, while B does not. This report presents the
preparation and characterization of n ) 1 macrocycles endowed
with a single peripheral metal-chelation site and their use in
preparing dinuclear, solitaire-porphyrazines14 such as those
illustrated in Chart 1. It includes the X-ray structures of a
solitaire-porphyrazines prepared with a [(diphophino)Pd]2+
capping moiety, 11b, and one with a [(diamine)Pt]2+ cap, 11h.
The spectroscopic and electrochemical properties of these
complexes are compared to those of related porphyrazine and
phthalocyanine complexes. The following paper (J. Am. Chem.
Soc. 1996, 118, 10487)13 describes the synthesis of n ) 2 and
3 macrocycles and their use in preparing n ) 2 trinuclear metal
complexes, the gemini-porphyrazines.
(10) (a) van Nostrum, C. F.; Picken, S. J.; Nolte, R. J. M. Angew. Chem.
Int. Ed. Engl. 1994, 33, 2173-2175. (b) Gu¨rek, A. G.; Ahsen, V.; Gu¨l,
A.; Bekaˆrogˇlu, O¨ . J. Chem. Soc. Dalton Trans. 1991, 3367. (c) Kobayashi,
N.; Higashi, Y.; Osa, T. J. Chem. Soc., Chem. Commun. 1994, 1785-1786.
(d) Sarigu¨l, S.; Bekaˆrogˇlu, O¨ . Chem. Ber. 1989, 122, 291-292. (e) Gu¨rek,
A. G.; Bekaˆrogˇlu, O¨ . J. Chem. Soc., Dalton Trans. 1994, 9, 1419-1423.
(f) Kocak, M.; Okur, A. I.; Bekaˆrogˇlu, O. J. Chem. Soc., Dalton Trans.
1994, 323-326. (g) Kobayashi, N.; Opallo, M.; Osa, T. Heterocycles 1990,
30, 389. (h) Kobayashi, N.; Lever, A. B. P. J. Am. Chem. Soc. 1987, 109,
7433-7441.
(11) (a) Velazquez, C. S.; Broderick, W. E.; Sabat, M.; Barrett, A. G.
M.; Hoffman, B. M. J. Am. Chem. Soc. 1990, 112, 7408-7410. (b)
Velazquez, C. S.; Fox, G. A.; Broderick, W. E.; Andersen, K. A.; Anderson,
O. P.; Barrett, A. G. M.; Hoffman, B. M. J. Am. Chem. Soc. 1992, 114,
7416-7424.
(12) Velazquez, C. S.; Baumann, T. F.; Olmstead, M. M.; Hope, H.;
Barrett, A. G. M.; Hoffman, B. M. J. Am. Chem. Soc. 1993, 115, 9997-
10003.
1
(13) See the following article: Sibert, J. W.; Baumann, T. F.; Williams,
D. J.; White, A. J. P.; Barrett, A. G. M.; Hoffman, B. M. J. Am. Chem.
Soc. 1996, 118, 10487.
(14) Baumann, T. F.; Sibert, J. W.; Olmstead, M. M.; Barrett, A. G. M.;
Hoffman, B. M. J. Am. Chem. Soc. 1994, 116, 2639-2640.
(15) Dhara, S. C. Indian J. Chem. 1970, 8, 193-194.
(16) Davison, A.; Holm, R. H. Inorg. Synth. 1967, 6, 8-15.

solitaire-Porphyrazines
J. Am. Chem. Soc., Vol. 118, No. 43, 1996 10481
[2,3-Bis((4-(butyloxycarbonyl)benzyl)thio)norphthalocyanato]-
magnesium(II), Mg(norpc(SR)2) (6). Magnesium metal (0.8 g, 0.033
mol) was added to n-BuOH (240 mL) and heated to reflux for 24 h.
Once boiling, a small chip of iodine was added to initiate the formation
of a magnesium butoxide suspension. A mixture of dinitrile 5 (2.61
g, 0.005 M) and 1,2-dicyanobenzene (16 g, 0.125 M) was added to the
solution, and the mixture was heated for an additional 12 h, turning
dark blue/green. The solvent was evaporated, and the residue was
treated with CHCl3. This solution was filtered to remove the insoluble
Mg(pc) byproduct. The crude reaction product was then chromato-
graphed on silica gel using, at first, CHCl3 and then 2% MeOH in
CHCl3, and the major blue band was collected. Overall yield was
8-10% based on dinitrile 5: UV/vis (CHCl3) λmax 358, 636, 652, 696
nm; FAB-MS 929 (M + H+).
with MeOH until washings were colorless. The solid was then
dissolved in CHCl3 and chromatographed on silica gel eluting with
2% MeOH/CHCl3. The major blue band was collected and dried in
vacuo to give 81 mg of product (30% yield): UV/vis (CHCl3) λmax
333, 603, 668 nm; FAB-MS 1041 (M + H+).
[(1,1′-Diphenylphosphino)ferrocene]palladium(II)[2,3-dithiola-
tonorphthalocyanine] ([(dppf)Pd][H2(norpc(S2))], 11b). Macrocycle
7 (0.25 g, 0.28 mmol) was deprotected, capped with (dppf)PdCl2, and
purified using the procedure above to yield 110 mg of product (35%
yield). The product was recrystallized from CH2Cl2/MeOH: 1H NMR
(CDCl3) δ (ppm) 9.59 (d, aromatic), 9.25 (d, aromatic), 9.15 (d,
aromatic), 8.30 (m, aromatic), 8.05 (m, aromatic), 7.65 (t, aromatic),
7.55 (t, aromatic), 4.48 (d, 4H-Cp), -0.75 (s, 2H-internal); UV/vis
(CHCl3) λmax 337, 592, 643, 722 nm; FAB-MS 1185 (M + H+).
2,3-Bis((4-(butyloxycarbonyl)benzyl)thio)norphthalocyanine, H2-
(norpc(SR)2) (7). Compound 6 (1.5 g, 1.6 mmol) was dissolved in
excess CF3CO2H (20-25 mL) and stored in the dark for 12 h. The
slurry was poured over ice water (300 mL) and neutralized with
concentrated ammonium hydroxide. The black solid was collected by
filtration and washed thoroughly with water, until neutral, and MeOH,
until washings were colorless. The blue solid was dissolved in CHCl3
and filtered to remove any insoluble black material. This blue solution
was taken to dryness under rotary evaporation and dried under vacuum
(1.4 g, 90%). 1H NMR (CDCl3) δ (ppm) 8.42 (d, 2H), 8.35 (d, 2H),
8.30 (d, 2H), 7.85 (d, 4H), 7.80 (d, 2H), 7.72 (m, 4H), 7.50 (d, 4H),
5.10 (s, 4H), 4.20 (t, 4H), 1.65 (qn, 4H), 1.35 (sx, 4H), 0.90 (t, 6H),
-2.78 (s, 2H); UV/vis (CHCl3) λmax 346, 610, 708 nm; FAB-MS 907
(M + H+).
[2,3-Bis((4-(butyloxycarbonyl)benzyl)thio)norphthalocyanato]-
nickel(II), Ni(norpc(SR)2) (8). The metal-free macrocycle 7 (1.0 g,
0.0011 mol), anhydrous Ni(OAc)2 (1.95 g, 0.011 m), PhCl (30 mL),
and DMF (10 mL) were heated to 120 °C under nitrogen for 5 h. The
solvent was removed under vacuum and the solid was washed with
5% HCl in MeOH and then MeOH. The product was dried under
vacuum (1.0 g, 95%): UV/vis (CHCl3) λmax 354, 638, 650, 696 nm;
FAB-MS 965 (M + H+).
[(1,1′-Diphenylphosphino)ferrocene]palladium(II)[2,3-dithiola-
tonorphthalocyaninato)nickel(II)] ([(dppf)Pd][Ni(norpc(S2))], 11c).
Macrocycle 8 (0.25 g, 0.26 mmol) was deprotected, capped with (dppf)-
PdCl2, and purified using the procedure above to yield 97 mg of product
(30% yield): UV/vis (CHCl3) λmax 333, 603, 666 nm; FAB-MS 1244
(M + H+).
[(1,1′-Diphenylphosphino)ferrocene]palladium(II)[(2,3-dithiola-
tonorphthalocyaninato)copper(II)] ([(dppf)Pd][Cu(norpc(S2))], 11d).
Macrocycle 9 (0.25 g, 0.26 mmol) was deprotected, capped with (dppf)-
PdCl2, and purified using the procedure above to yield 80 mg of product
(25% yield): UV/vis (CHCl3) λmax 339, 606, 679 nm; FAB-MS 1250
(M + H+).
[(Bis-triethylphosphine)]platinum(II)[2,3-dithiolatonorphthalo-
cyanine] ([(C2H5)3P]2Pt[H2(norpc(S2))], 11e). Macrocycle 7 (0.25 g,
0.28 mmol) was deprotected, capped with (Et3P)2PtCl2, and purified
using the procedure above to yield 95 mg of product (35% yield): UV/
vis (CHCl3) λmax 338, 591, 644, 725 nm; FAB-MS 959 (M + H+).
[(Bis-triethylphosphine)]platinum(II)[(2,3-dithiolatonorphthalo-
cyaninato)nickel(II)] ([(C2H5)3P]2Pt[Ni(norpc(S2))], 11f). Macrocycle
8 (0.25 g, 0.26 mmol) was deprotected, capped with (Et3P)2PtCl2, and
purified using the procedure above to yield 93 mg of product (35%
yield): UV/vis (CHCl3) λmax 333, 602, 669 nm; FAB-MS 1018 (M +
H+).
[2,3-Bis((4-(butyloxycarbonyl)benzyl)thio)norphthalocyanato]-
copper(II), (Cu(norpc(SR)2) (9). The metal-free macrocycle 7 (1.0
g, 0.0011 mol), anhydrous Cu(OAc)2 (1.95 g, 0.011 M), PhCl (30 mL),
and DMF (10 mL) were heated to 120 °C under nitrogen for 5 h. The
solvent was removed under vacuum, and the solid was washed with
5% HCl in MeOH and then MeOH. The product was dried under
vacuum (1.0 g, 95%): UV/vis (CHCl3) λmax 354, 638, 650, 696 nm;
FAB-MS 970 (M + H+).
[(Bis-triethylphosphine)]platinum(II)[(2,3-dithiolatonorphthalo-
cyaninato)manganese(III)chloride] ([(C2H5)3P]2Pt [Mn(norpc(S2))-
Cl], 11g). Macrocycle 10 (0.25 g, 0.25 mmol) was deprotected, capped
with (Et3P)2PtCl2, and purified using the procedure above to yield 82
mg of product (30% yield): UV/vis (CHCl3) λmax 352, 516, 656, 712
nm; FAB-MS 1047 (M - Cl-).
[N,N,N′,N′-Tetraethylethylenediamine]platinum(II)[(2,3-dithiola-
tonorphthalocyaninato)nickel(II)] [(teeda)Pt][Ni(norpc(S2))], 11h).
Macrocycle 9 (0.25 g, 0.26 mmol) was deprotected, capped with (teeda)-
PtI2, and purified using the procedure above to yield 0.065 mg of
product (25% yield): UV/vis (CHCl3) λmax 335, 609, 669 nm; FAB-
MS 950 (M + H+).
[2,3-Bis((4-(butyloxycarbonyl)benzyl)thio)norphthalocyanato]-
manganese(III) Chloride, Mn(norpc(SR)2)Cl (10). The metal-free
macrocycle 7 (1.0 g, 0.0011 mol), anhydrous MnCl2 (1.95 g, 0.011
M), PhCl (30 mL), and DMF (10 mL) were heated to 120 °C under
nitrogen for 5 h. The solvent was removed under vacuum, and the
solid was washed MeOH. The product was dried under vacuum (1.0
g, 95%): UV/vis (CHCl3) λmax 360, 496, 680, 749 nm; FAB-MS 961
(M - Cl-).
General Procedure for Deprotection of Macrocycles 7-10.
Schlenk techniques were used in this step. Macrocycle 8 (0.25 g, 0.26
mmol) was suspended in liquid NH3 (20 mL) at -78 °C. Sodium metal
(48 mg, 2.1 mmol), freshly cut under hexanes, was added in small
pieces, and, once dissolved, THF (10 mL) was added to solubilize the
porphyrazine. The reaction turned purple, then green, and ended as a
bluish/purple color. After 30 min, NH4Cl (70 mg, 1.3 mmol) was added
to quench to excess sodium and sodium amide. The NH3 and THF
were vented off under a stream of argon yielding a fine blue powder
containing sodium chloride and the disodium salt of the norphthalo-
cyaninedithiolate. Due to the air sensitive nature of the dithiolate, no
attempt at determining a yield was made, and this product was carried
on to the next step.
X-ray Crystallography of Complex 11b. The crystal selected for
data collection was mounted in the cold stream (130 K) of a Siemens
P4 diffractometer equipped with a LT-2 low-temperature apparatus.
The radiation employed was Ni-filtered Cu KR from a Siemens rotating
anode source operating at 15 kW. A linear decay of 4.5% in the
intensities of three standard reflections was observed during data
collection, and the data were scaled to adjust for this decay. Neutral
atom scattering factors were from a common source. The structure
was solved in the space group C2/c using direct and difference Fourier
methods.17 In addition to compound 11b, the structure contains two
molecules of solvent CH2Cl2. Hydrogens bonded to carbon were added
geometrically and refined by use of a riding model and isotropic thermal
parameters equal to 1.2 times the equivalent isotropic thermal parameter
of the bonded carbon. Hydrogens bonded to the nitrogen atoms of the
porphyrazine core were located on a difference Fourier map. In
subsequent cycles of refinement their positional parameters were
allowed to vary, but their isotropic thermal parameters were fixed at a
[(1,1′-Diphenylphosphinoethane)nickel(II)][(2,3-dithiolatonor-
phthalocyaninato)nickel(II)] ([(dppe)Ni][Ni(norpc(S2)], 11a). Mac-
rocycle 8 (0.25 g, 0.26 mmol) was deprotected by the method above.
The resulting dithiolate was redissolved in deaerated MeOH (30 mL).
To this solution was added (dppe)NiCl2 (0.165 g, 0.31 mmol) as a solid.
The blue solution was allowed to stir under argon for 2 h during which
time a blue precipitate formed. This solid was filtered and washed
(17) Tables of neutral atom scattering factors, f ′ and f ′′, and absorption
coefficients are from International Tables for Crystallography; Wilson, A.
J. C., Ed.; Kluwer Academic Publishers: Dordrecht, 1992; Vol. C, Tables
6.1.1.3 (pp 500-502), 4.2.6.8 (pp 219-222), and 4.2.4.2 (pp 193-199),
respectively.

10482 J. Am. Chem. Soc., Vol. 118, No. 43, 1996
Baumann et al.
Scheme 1a
being robust yet readily cleaved with sodium metal in liquid
ammonia.21 (ii) Alkylation of Na2(mnt) with butyl(4-chloro-
methyl)benzoate produces dinitrile 4 in high yields which can
be readily cyclized using the magnesium alkoxide method.22,23
(iii) Most importantly, the butyl ester lends sufficient solubility
for the isolation and purification of the protected porphyrazine.
In addition, transesterification which occurs during the butoxide
cyclization does not yield new products, as occurs with other
ester-substituted benzyl derivatives. (iv) Placement of the
electron-withdrawing ester moiety in the para position facilitates
the reductive cleavage of the benzyl protecting group, relative
to an unsubstituted benzyl group.
In practice, mixed condensation of BCB-protected dithioma-
leonitrile 5 and 1,2-dicyanobenzene (25-fold excess) followed
by treatment of the reaction product with CHCl3 allows for the
easy isolation of 6 in reasonable yield (15%). The magnesium
atom is cleanly removed from 6 using neat trifluoroacetic acid
to give 7, and remetalation with nickel, copper, and manganese
to give 8-10 proceeds smoothly using high-temperature meta-
lation conditions.24 Use of M ) Ni(II) and Cu(II) leads to the
M(II)(norpc(SR)2), 8 and 9; Mn(II) also incorporates into the
macrocyclic cavity but promptly air-oxidizes to Mn(III) within
the metalation reaction presumably with an axial chloride ligand.
Debenzylation of 7-10 was achieved by reductive cleavage with
sodium metal in liquid ammonia. The resulting norphthalo-
cyanine dithiolate is air-sensitive, and Schlenk techniques were
employed during all manipulations. The dithiolate dissolves
in deaerated MeOH to give a dark blue solution that may be
subsequently treated with various “capping” reagents to give
air-stable bi- and trimetallic solitaire-porphyrazine complexes
in yields of 25-35% based on the starting BCB-protected
porphyrazine. Chart 1 lists the solitaire-porphyrazines synthe-
sized.
X-ray Crystal Structure of 11b. solitaire-Porphyrazine 11b
has a [palladium(bis(1,1′-diphenylphosphino)ferrocene)]2+ moi-
ety coordinated to the peripheral dithiolate of the [H2-
(norpc(S2-))]2- core. The pertinent parameters for the data
collection and structure determination of 11b are compiled in
Table 1, and its molecular structure is shown in Figure 1a. A
comparison of bond lengths and bond angles for 3,12 11b, 11h,
and M(pc)25 is presented in Table 2. The macrocyclic ring of
11b is essentially planar with only modest deviations of the
peripheral fused benzene rings out of the least-squares plane
defined by the four pyrrole nitrogen atoms. The geometry of
the norphthalocyanine portion is similar to that of pc, with only
slight variations seen in the pyrrole containing the fused
dithiolene moiety. However, the asymmetry at the periphery
is nonetheless apparent at the core in that the internal N-H
protons are resolved in the X-ray structure, being localized on
pyrrole nitrogens N1 and N3.
The four-coordinate palladium ion is chelated by the two
dithiolene sulfurs and by the two phosphorus atoms of the 1,1′-
bis(diphenylphosphino)ferrocene moiety. As seen with the
tetranuclear complexes of nickel porphyrazineoctathiolate,12
[Ni(pzot)]8-, the dithiolene unit of 11b adjusts itself in order
to chelate the palladium ion by a swing of the Câ-S bond.
Whereas the Câ-Câ-S bond angle for the unconstrained
reference, Mg(octakis(methylthio)porphyrazine), Mg(otmp),11b
a (i) Mg(OBu)2, BuOH, reflux, 24 h; (ii) CF3COOH, 25 °C, 12 h;
(iii) M(II)(X)2 (X ) -OAc, Cl-), PhCl, DMF, 100 °C, 4 h; (iv) Na (4
equiv), NH3, THF, -33 °C, 0.5 h; (v) L2M′X2, MeOH, 25 °C, 1 h.
typical value of 0.03 Å2. An absorption correction (XABS18) was
applied. Final refinement was by full-matrix least-squares methods19
based on F2, using all data, with anisotropic thermal parameters for all
non-hydrogen atoms. The largest feature on a final difference map
was 0.71 eÅ-3 in magnitude, 2.2 Å from the chlorine of a CH2Cl2.
X-ray Crystallography of Complex 11h. Data for a thin green/
black plate were measured at room temperature on a Siemens P4
rotating anode diffractometer with graphite monochromated Cu-KR
radiation using ω-scans. Independent reflections (7827) were measured
(2θ e 100°), and of these 6497 had |Fo| > 4σ(|Fo|) and were considered
to be observed. The data were corrected for Lorentz and polarization
factors and for absorption-numerical correction for a face-indexed
crystal-minimum and maximum transmission factors 0.207 and 0.848,
respectively.
The structure was solved by direct methods, and all the major
occupancy non-hydrogen atoms in the complexes were refined aniso-
tropically. A ∆F map revealed the presence of 60:40 disorder in the
teeda ligand of one of the two independent complexes; the minor
occupancy carbon and nitrogen atoms were refined isotropically. The
structure was also found to contain two crystallographically independent
50% occupancy included CHCl3 molecules: only the chlorine atoms
were refined anisotropically. All hydrogen atoms were placed in
idealized positions, assigned isotropic thermal parameters, U(H) )
1.2Ueq(C) [U(H) ) 1.5eq(C-Me)], and allowed to ride on their parent
carbon atoms. Refinement was by full-matrix least squares based on
F2 and converged [∆/σ ratios less than 1σ for all parameters] to give
R1 ) 0.078, wR2 ) 0.201 for 1028 parameters. The maximum and
minimum residual electron densities in the final ∆F map were 2.42
and -1.93 eÅ-3, respectively, in the regions of the platinum atoms.
The somewhat high value of R1 is probably due to the poor crystal
qualitysthe thin plates tended to be deformed and gave diffuse
diffraction. Computations were carried out on an 50 MHz 486 PC
computer using the SHELXTL-PC program system.20
Results and Discussion
Synthesis of Bi- and Trimetallic solitaire Porphyrazines.
The synthesis of the solitaire-porphyrazines, 11a-h, begins with
the mixed condensation of a protected dithiomaleonitrile deriva-
tive and the commercially available 1,2-dicyanobenzene (Scheme
1). Normally a mixed cyclization would yield all six of the
porphyrazines that can result from the combination of the two
dinitriles in the reaction mixture. This problem is avoided by
using an excess of 1,2-dicyanobenzene to ensure that only two
major products are formed, Mg(pc) and Mg(norpc(SR)2). Mg-
(pc) is quite insoluble in most organic solvents, whereas Mg-
(norpc(SR)2) is soluble with the proper selection of a thiolate
protecting group. The 4-(butyloxycarbonyl)benzyl (BCB) pro-
tecting group was chosen for several reasons. (i) The benzyl
protecting group is well-established in thiolate chemistry as
(21) Greene, T. W.; P. G. M. In ProtectiVe Groups in Organic Synthesis;
John Wiley and Sons Inc.: New York, 1991; Chapter 6, pp 277-308.
(22) Linstead, R. P.; Whalley, M. J. Chem. Soc. 1952, 4839-4846.
(23) Schramm, C. J.; Hoffman, B. M. Inorg. Chem. 1980, 19, 383-
385.
(24) Buchler, J. W. In The Porphyrins; Dolphin, D., Ed.; Academic
Press: New York, 1978; Vol. 1, Chapter 10.
(18) XABS2: an empirical absorption correction program. Parkin, S.;
Moezzi, B.; Hope, H. J. Appl. Cryst. 1995, 28, 53-56.
(19) SHELXL-93 (Sheldrick, G. M. J. Appl. Cryst. 1994, in preparation.)
(20) SHELXTLPC version 5.03, Siemens Analytical X-Ray Instruments,
Madison, WI, 1994.
(25) Schramm, C. J.; Scaringe, R. P.; Stojakovic, D. R.; Hoffman, B.
M.; Ibers, J. A.; Marks, T. J. J. Am. Chem. Soc. 1980, 102, 6702-6709.

solitaire-Porphyrazines
J. Am. Chem. Soc., Vol. 118, No. 43, 1996 10483
Table 1. Crystal Data and Structure Refinement for solitaire-Porphyrazines 11b and 11h
11b
11h
empirical formula
formula weight
temperature
C64H46Cl4FeN8P2PdS2
1357.20
125(2) K
C38H36N10NiPtS2‚1/2CHCl3
1010.37
293(2) K
wavelength
1.54178 Å
1.54178
crystal system
space group
unit cell dimensions
monoclinic
C2/c
triclinic
P1
a ) 37.916(7) Å
b ) 10.807(1) Å
c ) 29.588(4) Å
R ) 90°
a ) 13.160(12) Å
b ) 16.526(10) Å
c ) 20.374(11) Å
R ) 113.80(4)°
â ) 92.93(6)°
γ ) 98.34(6)°
3982(5) Å3
â ) 109.85(1)°
γ ) 90°
vol.
Z
11404(3) Å3
8
4a
density (calc)
absorption coefficient
F(000)
1.581 mg/m3
7.929 mm-1
5504
1.685 mg/m3
9.310 mm-1
2004
crystal size
θ range for data collection
index ranges
0.18 × 0.08 × 0.03 mm
2.48-56.07°
-40 e h e 38
0 e k e 11
0 e l e 31
8082
0.30 × 0.20 × 0.02 mm
2.39-50.00°
0 e h e 11
-16 e k e 16
-20 e l e 20
7827
reflections collected
independent reflections
absorption correction
refinement method
data/restraints/parameters
goodness-of-fitc on F2
final R indicesd [I > 2σ(I)]
R indices (all data)
7439 (Rint ) 0.024)
7827 (Rint ) 0.000)
XABS2b
integration
full-matrix least squares on F2
7439/0/749
1.022
R1 ) 0.0469, wR2 ) 0.1140
R1 ) 0.0611, wR2 ) 0.1245
0.708 and -0.745 e Å-3
7819/25/1028
1.088
R1 ) 0.0775, wR2 ) 0.2007
R1 ) 0.0917, wR2 ) 0.2149
2.415 and -1.929 e Å-3
largest diff. peak and hole
a There are two crystallographically independent molecules in the asymmetric unit. b XABS2 (Parkin, S.; Moezzi, B.; Hope, H. J. Appl. Cryst.
1995, 28, 53-56) calculates 24 coefficients from a least-squares fit of (1/A vs sin2(θ)) to a cubic equation in sin2 θ by minimization of Fo2 and Fc2
2
differences. c Goodness-of-fit ) [∑[w(Fo - Fc2)2]/(M - N)]1/2 where M is the number of reflections and N is the number of parameters refined.
2
2
d R1 ) ∑|Fo - Fc|/∑|Fo|; wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo )2]]1/2
.
is 128.5(35)°, the same angle in 11b closes to 124.0(7)°.
Likewise, the distance between the sulfurs decreases from 3.53
Å in Mg(omtp) to 3.31 Å in 11b.
ordinated to the peripheral dithiolate of the [Ni(norpc(S2-))]2-
core, and Table 1 contains the pertinent parameters for the data
collection and structure determination of 11h. Figure 1b
illustrates one (A) of the two crystallographically independent
molecules (A and B) of 11h present in the asymmetric unit;
the other molecule (B) has only slight differences in the
orientations of the ethyl groups of the teeda ligand. The central
nickel atoms in both A and B adopt normal square-planar
geometries with Ni-N bond lengths in the range 1.88(1)-1.91-
(1) Å for molecule A and 1.86(1)-1.88(1) Å for molecule B.
The peripheral platinum atoms also have conventional square
planar geometries with Pt-S distances of 2.273(4) and 2.265-
(5) Å in A and 2.267(5) and 2.251(5) Å in B; the Pt-N distances
in both A and B are all normal at ca. 2.06 Å. The S-Pt-S
angles are 91.2(2) and 91.7(2)° in A and B, respectively,
reflecting the optimization of the norphthalocyanine-2,3-dithi-
olato chelate by a swing of the Câ-S bond as noted above for
11b; the N-Pt-N angles are slightly contracted at 84.7(6) and
84.1(5)° in A and B, respectively, compared to the expansion
for P-Pd-P in 11b.
The principal difference between the two molecules of 11h
is in the relative planarities of the porphyrazine units. In
molecule A this unit exhibits a very pronounced “dishing”sthe
central core of nickel-coordinated nitrogen atoms is coplanar
to within 0.004 Å (with the nickel atom deviating by 0.05 Å
“below” this plane), whereas the platinum atom and the centroids
of the three exocyclic six-membered rings [associated with
N(22), N(23), and N(24)] lie 0.35, 0.31, 0.46, and 0.18 Å
“above” this plane, respectively. In contrast, molecule B is
essentially planar. The comparative values for molecule B (in
which the four nickel-coordinated nitrogen atooms are coplanar
to within 0.02 Å) are 0.007 Å below and 0.22, 0.11, 0.02, and
To our knowledge, there is only one reported crystal structure
of a (P-P)Pd(II) complex bearing a dithiolate chelating ligand,
that of (dithiooxalato-S,S′)bis(trimethylphosphine)palladium-
(II).26 The Pd-S and Pd-P bond distances for 11b of 2.316-
(5) and 2.326(4) Å, respectively, are similar to the values for
that structure (2.300 and 2.334 Å). The bond angles around
palladium are not all equal for 11b, with S-Pd-S and P-Pd-P
angles of 90.6(5)° and 97.9(5)°, respectively. These values
differ slightly (∼3°) from the literature reference, probably
because the phosphine ligands are different. The ferrocene
portion of the diphosphine cap is structurally similar to free
ferrocene, and the average Fe-C bond distance of 2.043(6) Å
is comparable to the reported value of 2.04(2) Å.27
Each macrocycle in the unit cell stacks with an centrosym-
metrically-related porphyrazine to form a back-to-back “dimer”
(Figure 2a). The interplanar separation of the overlapped
portions of the porphyrazine planes in each pair is 3.13 Å. The
degree of overlap of the two porphyrazine planes in the dimer,
however, is limited due to the bulky 1,1′-(diphenylphosphino)-
ferrocene moiety. The macrocycles pack is dimerized slipped-
stack chains with significant π-π overlap between the fused
isoindole rings of adjacent sets of dimers (Figure 3a). The
phenyl groups of the dppf ligand are brought into the range for
numerous edge-to-face phenyl-phenyl interactions between the
stacked chains of porphyrazine dimers.
X-ray Crystal Structure of 11h. solitaire-Porphyrazine 11h
has a platinum[N,N,N′,N′-tetraethylenediamine]2+ moiety co-
(26) Cowan, R. L.; Pourreau, D. B.; Rheingold, A. L.; Geib, S. J.; Trogler,
W. C. Inorg. Chem. 1987, 26, 259.
(27) Dunitz, J. D.; Orgel, L. E.; Rich, A. Acta Crystallogr. 1956, 9, 373.

10484 J. Am. Chem. Soc., Vol. 118, No. 43, 1996
Baumann et al.
Table 2. Comparison of Symmetry-Averaged Bond Lengths and
Bond Angles for Complex 11b, 11h, M(pc),a and (3)
[(dppe)Ni]4[Ni(pzot)]b
11b
11h
M(pc)
3
Bond Distance (Å)
1.88(2)
Ni-Np
CR-Np
CR-Câ
Câ-Câ
CR-Nm
Câ-Cγ
Cγ-Cδ
Cδ-Cδ
Câ-S
1.88(6)
1.376
1.453
1.395
1.328
1.387
1.388
1.394
1.71(1)
3.25
1.87(3)
1.41(1)
1.46(3)
1.36(1)
1.34(3)
1.369(8)
1.455(9)
1.392(7)
1.328(8)
1.387(9)
1.382(9)
1.391(9)
1.739(8)
3.31
1.38(2)
1.45(2)
1.37(3)
1.33(2)
1.39(3)
1.37(3)
1.38(3)
1.73(2)
3.30
S‚‚‚S
Bond Angles (deg)
89.9(6)
Np-Ni-Np
Np-Ni-Np′
CR-Câ-Câ
CR-Np-CR
Nm-CR-Np
Nm-CR-Np
CR-Nm-CR
Np-CR-Câ
Câ-Câ-S
90
180
90.0(17)
178.7(1)
107.0(8)
103.5(7)
126.3(12)
126.3(12)
120.8(19)
110.0(14)
123.5(5)
129.5(13)
177.1(5)
106(2)
108.4(7)
106.7
108.1
127.7
127.7
123.2
109.3
108.9(7)
128.1(7)
128.1(7)
122.6(5)
108.8(6)
124.0(7)
127.6(4)
106.2(13)
127(2)
127(2)
121.5(14)
110.0(12)
123.1(13)
129.4(14)
CR-Câ-S
a Averaged for Mg(pc), Zn(pc), Fe(pc), and Mn(pc) structures, except
for Ni-Np, which is taken from Ni(pc)I. See ref 25. b Reference 12.
interplanar separation between the nickel-coordinated nitrogen
atoms of 11hB is only slightly increased compared to 11hA at
3.29 Å, but with the Ni‚‚‚Ni separation markedly increased to
4.96 Å [cf. 3.41 Å for A], i.e., a lateral shift of 3.7 Å. The
shortest intermolecular N‚‚‚N contact within the 11hB dimer
is 3.34 Å between N(23) and its centrosymmetrically related
counterpart.
The 11hA dimer pairs form a stepped stack (Figure 3b) with
the Pt-teeda units in one pair overlaying those of centrosym-
metrically related pairs. The interpair Pt‚‚‚Pt distances for 11hA
are 5.11 Å, precluding any significant interdimer interactions.
Dimer pairs of 11hB type molecules also from stepped stacks,
though in this instance there is significant π-π overlap between
isoindole rings (cis to Pt) in adjacent, centrosymmetrically
related dimer pairs (Figure 3c). The packing of 11hB is quite
similar to 11b, but with a lesser degree of overlap of the fused
benzo rings of adjacent dimers. In 11hB, there is nearly 50%
overlap between the six-membered ring components, with a ring-
centroid‚‚‚ring-centroid separation of 3.67 Å and a mean
interplanar separation of 3.44 Å.
For 11h, the type A and type B dimer pairs do not interact
with each other, their respective planes being steeply inclined
by ca. 51°. The intramolecular Ni‚‚‚Pt distances are 7.12 and
7.10 Å for A and B, respectively. The shortest intermolecular
Pt‚‚‚Ni distance is 6.08 Å between the nickel atom of a type A
molecule and the platinum atom of a type B moelcule. Again
this is similar to the lack of interaction between the equivalent
inclined stacks of 11b.
Electronic Absorption Spectroscopy. The optical spectra
of all porphyrazine derivatives exhibit two main bands, a Soret
or B band (π f π*) between 330-375 nm and another beyond
650 nm, denoted the Q band (π f π*). The 4-fold symmetric
macrocycles with four fused benzene rings (Ni(pc)) or four
protected dithiolene moieties (Ni(obtp)) at the periphery have
similar optical spectra, with single transitions for both the Q
and B bands. In contrast, the optical spectra of unsymmetrical
porphyrazines 6-10, with three fused benzo rings and n ) 1
protected dithiolene moiety, clearly show a splitting of the Q
band (Figure 4). As discussed in the following paper (J. Am.
Figure 1. Structures of 11b and 11hA showing 50% probability
thermal ellipsoids. For clarity, the heteroatoms have been labeled and
the hydrogen atoms have been omitted.
0.11 Å above for the deviations of the nickel atom, platinum
atom, and exocyclic ring centroids, respectively.
As with 11b, each of the independent molecules of 11h packs
with a centrosymmetrically-related counterpart to form a back-
to-back “dimer”. Although the interplanar separations are very
similar, the relative degrees of overlap between the porphyrazine
rings in each of the three cases (11b and 11h A and B) is
markedly different, with the overlap being least for 11b (Figure
2). For molecule 11hA, ring-ring overlap is maximized (Figure
2b), though at the expense of the marked dishing of the molecule
(Figure S1) described above. The mean interplanar separation
between the planes define by the four nickel-coordinated
nitrogens atoms is 3.20 Å, the Ni‚‚‚Ni separation being 3.41
Å, i.e., the molecules are sheared by ca. 1.2 Å with respect to
each other. The shortest intermolecular Ni‚‚‚N contact is 3.28
Å to Ni(24), whilst the sulfur atom S(2), which overlays an
exocyclic six-membered ring, is ca. 4.0 Å distant from the mean
plane of this ring. The mean interplanar separation between
the overlapping isoindole rings is ca. 3.6 Å. Molecules of type
11hB, which have a much more planar geometry than 11hA
(Figure S2), have an offset back-to-back “dimer” relationship
similar to but less extreme than that of 11b (Figure 2c). The

solitaire-Porphyrazines
J. Am. Chem. Soc., Vol. 118, No. 43, 1996 10485
Figure 2. Parallel projection onto the mean plane of the four nickel-
coordinated nitrogen atoms, showing the markedly different degree of
overlap of pairs of centrosymmetrically-related molecules for (a)11b,
(b)11hA, and (c)11hB.
Figure 3. The stepped stack motif exhibited by the “dimer pairs” of
molecules for (a)11b, (b)11hA, and (c)11hB. For clarity, the phenyl
groups of the dppf ligand of 11b have been omitted.
Chem. Soc. 1996, 118, 10487),13 these differences can be
rationalized through Gouterman’s highly simplified four orbital
model29 for the optical spectra of porphyrins and porphyrazines.
Surprisingly, the peripherally metalated solitaire-porphyra-
zines do not show a splitting of the Q-band: their optical spectra
look quite like those of an M(pc) (Figure 4). This effect might
reflect a modest extension of the porphyrazine π-system into
the five-membered chelate ring mediated by the dithiolate
moiety. Alternatively, a metal ion bound to the sulfurs might
significantly change their ability to donate electrons to the
porphyrazine ring, accidentally undoing the change in the
relative energies of the frontier orbitals.
Electron Paramagnetic Resonance. Whereas the optical
spectra provide evidence as to perturbations of the porphyrazine
π-system by peripheral substitutions, EPR studies of the
unpaired σ-electron on the Cu2+ of a Cu(porphyrazine) provide
evidence as to perturbations of the σ-system. The EPR spectrum
at 77 K of a powder sample of 1% Cu solitaire-porphyrazine
11d magnetically diluted in its diamagnetic host 11b shows axial
symmetry as is typical for monomeric square-planar Cu(II)
complexes21,30,31 with resolved 63Cu and 14N hyperfine. The
spin Hamiltonian parameters are listed in Table 3. Interestingly,
the parameters for 11d fall between those of Cu(omtp)23 and
Cu(pc),31 showing there are no more than small effects of
functionalization at the macrocyclic periphery on the electronic
structure of the central Cu(II) ion. The Mn(III) porphyrazines,
10 and 11g, are EPR silent at 77 K consistent with an even-
spin d4 system.32
Electrochemistry of solitaire-Porphyrazines. Typical
phthalocyanines and porphyrins undergo two ring oxidations
and up to four successive ring reductions.33,34 For phthalocya-
(30) Harrison, S. E.; Assour, J. M. J. Chem. Phys. 1964, 40, 365.
(31) Brown, T. G.; Peterson, J. L.; Lozos, G. P.; Anderson, J. R.;
Hoffman, B. M. Inorg. Chem. 1977, 16, 1563.
(32) Lever, A. B. P. J. Chem. Soc. 1965, 1821.
(33) Bottomley, L. A.; Chiou, W. J. H. J. Electroanal. Chem. 1986, 198,
331-346.
(34) (a) Clark, D. W.; Hush, N. S. J. Am. Chem. Soc. 1965, 87, 4238.
(b) Clark, D. W.; Yandle, J. R. Inorg. Chem. 1972, 11, 1738.
(28) Lever, A. B. P. AdV. Inorg. Chem. Radiochem. 1965, 7, 28.
(29) Gouterman, M. In The Porphyrins; Dolphin, D., Ed.; Academic
Press: New York, 1978; Vol. III, pp 1-165.

10486 J. Am. Chem. Soc., Vol. 118, No. 43, 1996
Baumann et al.
Table 4. Comparison of Half-Wave Potentialsa of the Ring
Reductions, RR’s, for 7, 11b, H2(obtp), and H2(pc)
macrocycle
E1/2(RR1)
E1/2(RR2)
7
-1.23
-1.27
-1.20
-0.85
-1.59
-1.51
-1.54
-1.19
11b
H2(pc)b
H2(obtp)
a Half-wave potentials are reported vs (Fc+/Fc) couple. The
electrochemistry for 7, 11b, and H2(obtp) were performed in CH2Cl2
with 0.1 M TBAPF6 as the electrolyte using a Pt working electrode
and a Ag/AgCl reference electrode. b Reference 35.
associated with the ferrocene portion of the diphosphine ligand
(+0.18 V vs Fc+/Fc). There also appears to be an irreversible
wave, +0.63 mV vs (Fc+/Fc), most likely associated with a
Pd(III/II) oxidation. Unlike the metal bis(dithiolene) systems
that undergo a reversible M(III/II) oxidation,35 this [S2MP2]
ligand environment is unable to stabilize the oxidized metal
center. Such an irreversible wave is seen for all the other (P-
P)M(II)-capped solitaire-porphyrazines, 11a-g. solitaire-Por-
phyrazine 11h, on the other hand, appears to show a reversible
oxidation at +0.43 mV (vs Fc+/Fc) that is associated with the
oxidation of the peripheral [S2PtN2] unit. The amine nitrogens
of the teeda ligand are better σ-donors than the phosphorus
ligands and apparently they stabilize the oxidized metal center
better. The details of this oxidation process are currently under
investigation.
Figure 4. Comparison of the Q band region for both metalated and
metal-free phthalocyanine with compounds 6, 7, and 11d (20 µM in
CH2Cl2).
Acknowledgment. This work was supported by the National
Science Foundation (CHE-9408561).
Table 3. EPR Parameters for solitaire-Porphyrazine 11d and
Related Cu(II) Macrocyclesa
Supporting Information Available: For complex 11b:
Figure showing the numbering scheme, displacements from the
least-squares plane, and unit cell packing diagrams and tables
of crystal data and structure refinement, atomic coordinates and
equivalent isotropic displacement parameters, bond lengths and
angles, anisotropic displacement parameters, and hydrogen
coordinates and isotropic displacement parameters. For complex
11h: Figure showing the numbering scheme, side view of 11hA
showing the pronounced dishing of the porphyrazine (Figure
S1), the side view of 11hB showing the noticeably more planar
conformation of the porphyrazine core (Figure S2), and tables
of crystal data and structure refinement, atomic coordinates and
equivalent isotropic displacement parameters, bond lengths and
angles, anisotropic displacement parameters, and hydrogen
coordinates and isotropic displacement parameters. A table of
elemental analyses for the BCB-protected precursors, 6-10, and
solitaire-porphyrazines, 11a-h, is included along with a table
of their electronic absorption maxima and molar extinction
coefficients (31 pages). See any current masthead page for
ordering and Internet access information.
complex
g|
A|Cu
AN
BN
Cu(pc)b
11d;9c
2.18
2.16
2.14
604
635
644
53.4
55.9
57.4
40.7
41.6
43.3
Cu(omtp)d
a Hyperfine coupling constants are expressed in units of megahertz.
b Reference 32. c Values for the two compounds are indistinguishable.
d Reference 23.
nines specifically, the reductions are usually reversible, but the
oxidations are not. As representatives of the compounds
prepared here, the electrochemistry of solitaire-porphyrazine 11b
and the precursor 7 was examined. Within the accessible
potential range of the CH2Cl2/tetrabutylammonium hexafluo-
rophosphate solvent/electrolyte system, both macrocycles exhibit
two reversible one-electron reductions, which, likewise, are
attributed to reductions of the porphyrazine ring π-system. As
seen in Table 4, the potentials for the ring reductions of both 7
and the solitaire-porphyrazine 11b occur at ∼ -1.20 and
∼ -1.60 V (vs Fc+/Fc), essentially the same as for H2(pc) but
significantly higher than for H2(obtp) (-0.85 and -1.19 V).
Within the limit of +150 V as determined by the solvent (CH2-
Cl2), no ring oxidation were observed for either 7 or 11b.
For solitaire-porphyrazines with the coordinated [1,1′-(di-
phenylphosphino)ferrocene]palladium(II) cap, 11b-d, the cyclic
voltammogram showed a reversible one electron oxidation
JA9619115
(35) (a) Davison, A.; Edelstein, N.; Holm, R. H.; Maki, A. H. Inorg.
Chem. 1963, 2, 1227-1232. (b) Billig, E.; Williams, R.; Bernal, I.; Waters,
J. H.; Gray, H. B. Inorg. Chem. 1964, 3, 663-666. (c) Vance, C. T.;
Bereman, R. D. Inorg. Chim. Acta 1988, 149, 229-234.