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Highly Polarizing Co2+ Ions from [Co2(CO)8] and Pyridine in Hydrocarbons Synthesis and Structure of [{CO3(CO)10}2{Co(py)4}] and [(CO4CoCo(py)3][Co(CO)4].

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between the two isomeric sets of phenylene-linked dimers
are seen in the case of the bis-zinc(ii) complexes. The biszinc complexes of the p-phenylene-linked compounds 2,
13, and 14 all display one strong Soret band at ca. 420425 nm with only a faint shoulder appearing at higher energy. The bis-zinc(ii) complexes of the “gable”-type porphyrins 1, 1 1 , and 12, on the other hand, all display a
Soret band that is split into two peaks of nearly equal intensity (at ca. 412 and 428 nm). This splitting of the Soret
band, arising by virtue of dipole-dipole coupling, is indicative of interaction between the two porphyrin chromophores.[‘I The observation of fluorescence quantum yields
for the meta-linked dimers 3 and 11 that are both lower by
ca. 25% than those of the corresponding p-phenylenelinked analogues (4 and 13) further confirms that a greater
level of excitonic interaction pertains in the “gable” series
of dimers.
As was expected on the basis of earlier work with quinone-substituted monomeric porphyrins,‘] ‘I neither I nor
2, as ca. lo-” M solutions in toluene, showed detectable
fluorescence when irradiated at L=418 nm (@<
This suggests that rapid photoinduced intermolecular electron transfer is occurring from the porphyrins to the quinone acceptors. Compounds 1 and 2 thus appear to be
suitable systems with which to model the primary events of
photosynthetic charge separation.
Received: January 22, 1987 [Z 2063 IE]
German version: Angew. Chem. 99 (1987) 679
[ I ] J. Deisenhofer, 0. Epp, K. Miki, R. Huber, H. Michel, J . Mol. Biol. 180
(1984) 385.
121 J. Weiser, H. A. Staab, Angew. Chem. 96 (1984) 602; Angew. Chem. In!.
Ed. Engl. 23 (1984) 623; B. Morgan, D. Dolphin, ibid. 97 (1985) 1000
and 24 (1985) 1004, and references cited therein; P. Leighton, J. K. M.
Sanders, J. Chem. Soc. Chem. Commun. 1985. 24; J. R. Bolton, T.-F. Ho,
S . Liauw, A. Siemiarczuk, C. S. K. Wan, A. C. Weedon, ibid. 1985. 559;
M. R. Wasielewski, M. P. Niemczyk, W. A. Svec, E. B. Pewitt, J. Am.
Chem. Soc. 107 (1985) 1080, 5562; J. A. Schmidt, A. Siemiarczuk, A. C .
Geedon, J . R. Bolton, ibrd. 107 (1985) 61 12; B. A. Leland, A. D. Joran, P.
M. Felker, J. J. Hopfield, A. H. Zewail, P. B. Dervan, J . Phys. Chem. 89
(1985) 5571; C. Krieger, J. Weiser, H. A. Staab, Tetrahedron Letr. 26
(1985) 6055: J. Weiser, H. A. Staab, ibid. 1985. 6059; A. Osuka, H. Furuta, K. Maruyama, Chem. Lett. 1986,479; D. N. Beratan, J. Am. Chem
Soc. 108 (1986) 4321; 0. Gust, T. A. Moore, L. R. Makings, P A. Liddell, G. A. Nemeth, A. L. Moore, ibid. 108 (1986) 8028.
a) Only one report of a quinone-substituted porphyrin dimer has appeared: Y . Sakata, S. Nishitani, N. Nishimizu, S. Misumi, A. R. Mclntosh, J. R. Bolton, Y . Kanda, A. Karen, T. Okada, N. Mataga, Tetrahedron Lett. 26 (1985) 5207; b) for examples of photosynthetic models
containing two o r more porphyrin-like macrocycles (but no quinones)
see: S. G . Boxer, Biochim. Biophvs. Acta 726 (1983) 265, and references
cited therein; M. R. Wasielewski, M. P. Niemczyk, W. A. Svec, Tetruhedron Letr. 23 (1982) 3215; J. C . Mialocq, C . Giannotti, P. Maillard, M.
Momenteau, Chem. Pliw. Lett. 112 (1984) 87: G . M. Dubowchik, A. D.
Hamilton, J . Chem Soc. Chem. Commun. 1986. 665, 1391; R. L. Brookfield, H. Ellul, A. Harriman, G. Porter, J. Cliem. Soc. Furadu-v Trans. 2
1986. 219. c) The synthesis of an analogue of the unsubstituted photosynthetic model compound 4 was reported subsequent to the submission of this work: D. Heiler, G. McLendon, P. Rogalskyj, J. Am. Chem.
Soc. 109 (1987) 604.
I. Tabushi, T. Sasaki, Tetrahedron Lett. 23 (1982) 1913; 1. Tabushi, S.-I.
Kugimiya. M. G. Kinnaird, T. Sasaki, J . Am. Chem. Soc 107 (1985)
a ) G. P. Arsenault, E. Bullock, S. F. MacDonald, J . Am. Chem. Soc. 82
(1960) 4384: b) C . K. Chang, I . Abdalmuhdi, Angew. Chem. 96 (1984)
154: Angew. Chem. 1nt. Ed. Engl. 23 (1984) 164; c) 1. Abdalmuhdi, C . K.
Chang, J. Orq. Chem. 51) (1985) 41 1 ; d) S. S. Eaton, G. R. Eaton, C . K.
Chang, J . Am. Chem. Soc. 107 (1985) 3 177.
J. L. Sessler, J. Hugdahl, M. R. Johnson, J . Org. Chem. 51 (1986) 2838.
J L. Archibald, D. M. Walker, K. B. Shaw, A. Markovac, S. F. MacDonald. Can. J. Chem. 44 (1966) 345; D. H. R. Barton, S. Z. Zard, J. Chem.
Soc. Chem. Commun. 1985. 1098.
With the exceptions of 14, which proved too insoluble to purify, and 12,
which was only Characterized spectroscopically, all new porphyrin com-
0 VCH Verlags~erell.sclia/rmhH. D-6940 Weinheim. 1987
pounds gave satisfactory spectroscopic, analytical, and mass spectral
data; dipyrrolic intermediates were characterized by ‘H-NMR and highresolution mass spectrometry.
191 R. Chong, P. S. Clezy, A. J. Liepa, A. W. Nichol, Ausrr. J . Chem. 22
(1969) 229.
1101 C . K. Chang, I . Abdalmuhdi, J . Org. Chem. 48 (1983) 5388.
[ I l l J. Dalton, L. R. Milgrom, J. Chem. Soc. Chem. Commun. 1979, 609; A.
Harriman. R. J. Hosie, J. Chem. Soc. Farads-v T r a m 2 1981. 1695; M. A.
Bergkamp, J. Dalton, T. L. Netzel. J . Am. Chem. Soc. 104 (1982) 253; A.
C . Chan, J. Dalton, L. R. Milgrom, J . Chem. Soc Perkin Trans. 2 1982.
Highly Polarizing Coz+ Ions
from [CoZ(CO),]and Pyridine in Hydrocarbons:
Synthesis and Structure of ~{Co3(CO),o}z(Co(py)4]l
and I(CO)4CoCo(p~)31~Co(CO)~l**
By Giuseppe Fachinetti,* Giovanni Fochi, Tiziana Funaioli.
and Pier Francesco Zanazzi*
Large excesses of Lewis bases promote metal carbonyl
disproportionation,”’ with base-encapsulated cations and
carbonylmetalate anions being formed. However, when relatively weak bases or only moderate amounts of strong
bases in solvents having low dielectric constants are used,
the disproportionation of neutral metal carbonyls yields
complex cations and carbonylmetalate anions associated
in homonuclear ion pairs (HNIP).”] The reactivity of the
anions is affected by ion pairing with acidic countercations;131therefore, H N I P phenomena are likely to yield a
better understanding of metal carbonyl chemistry. Firm
evidence for such behavior was obtained in the case of
[V(CO),] 1 and [Fe(CO),] 2 . The reaction of 1 with tetrahydrofuran (THF) gave the structurally characterized complex [(OC)5VCOV(tht),0CV(CO)5];”1
similarly, 2 reacts
with pyridine (py) to yield the tetranuclear H N I P
[(p ~Fe)Fe(~CO)4]2.161The molecu I a r structure shows cat ion-anion association through direct metal-metal interactions. Upon addition of moderate amounts of py to
[Co2(CO),] 3 in T H F solution, we obtained spectroscopic
evidence for a CO”/[CO(CO)~]- HNIP,”’which led to the
formation of both isocarbonyl compounds and species
showing direct metal-metal interactions. We now report
that, in hydrocarbon solutions containing moderate
amounts of py with respect to the cobalt, H N I P formation
from 3 occurs; two compounds of this class have been isolated and their molecular structures solved.
The addition of an equimolar amount of py to 3 in nhexane results in gas evolution and the formation of a carmine solid in 60% yield analyzing as [Co,(CO),,,(py),] 4.[’l
The IR spectrum (Nujol mull) in the C O stretching region
(2078 (w), 2016 (vs), 1995 (sh), 1980 (m), 1964 (m), 1520 (m)
cm- I) resembles the pattern for the [Co,(CO),,)]- cluster
in ether solvents.[41Crystals suitable for X-ray diffraction
grew from the mother
Complex 4 (Fig. 1) contains an approximately octahedrally coordinated Co’+ ion bound to four py nitrogen
atoms in the equatorial plane; the axial positions are occupied by the carbonyl oxygen atoms of the kL,-COgroups
[*I Prof. G. Fachinetti, Dr. G. Fochi, Dr. T. Funaioli
Dipartimento di Chimica e Chimica lndustriale
dell’universita degli Studi di Pisa
Via Risorgimento 35, 1-56 100 Pisa (Italy)
Prof. P. F. Zanazzi
Dipartimento di Scienze della Terra
dell’Universit8 degli Studi di Perugia
Piazza dell’Universita, 1-06 100 Perugia (Italy)
This work was supported by the Minister0 della Pubblica lstruzione
(Rome). We thank Prof. Fausto Culderazzo for helpful discussions.
0570-0833/87/0707-0680 $ 02.50/0
Angew. Chem. In!. Ed. Engl. 26 11987) No. 7
synproportionation of metal carbonyls can occur with"'] or
without the intermediacy of isocarbonyl compounds.
These findings show that, through a base-promoted disproportionation reaction, [Co,(CO),] 3 can be the source
of highly polarizing C o z c ions when only moderate
amounts of bases are employed.
Received: February 2, 1987 [Z 2081 IE]
German version: Angew. Chem. 99 (1987) 68 I
0 3
tig. I . 'Liolecular crystal structure of [(Co,(CO),,~12(Co(py)ilj
4. Important
distances [A] and angles ["I: Co-Co (in the [Col(C0),,,]- units) 2.502 (average): C - 0 (terminal) 1.16 (average); C21-01 1.233(12), C22-02 1.239(13),
f o l - O l 2.154(7), C o l - 0 2 2.146(7), C o l - N 2.144; C21-01-Col 168.7(6), C2202-Col 173.0(6) (average).
belonging to two [CO,(CO),~]-units. The interatomic distances and angles in the two [CO,(CO),~]- clusters are
comparable to those reported for other oxymethylidyne
Co7(CO)9 cI us ters.141
Complex 4 is indefinitely stable in the solid state but
decomposes quickly in T H F o r toluene, dark green solutions being obtained. In both these solvents, the IR spectra
show the complex pattern already observed"] for T H F solutions of 3 containing moderate amounts of py, thus indicating the formation of other types of Co'+/[Co(CO),]HNIPs from 4. Slow diffusion of n-hexane vapor into
a toluene solution of 4 resulted in the formation of
large black-green crystals having the composition
[C0,(C0)~(py),] 5 in low yield.f"'l The IR spectrum of 5
(Nujol mull) shows absorptions at 2050 (m), 1992 (m),
1947 (s), 1933 (s), 1887 (m), and 1867 (s) c m - ' . Complex 5
can be obtained in 90% yield directly from 3 and py in
tolueneln-hexane mixtures." 'I The X-ray crystal structure
analysis of 5 showed that it consists of nearly regular
[(0C),C0Co(py)~]+ cations (Fig. 2). The geometry around
the cobalt carrying the carbonyl groups is a distorted trigonal bipyramid, while that around the cobalt carrying the
py groups is a distorted tetrahedron. The Co-Co distance
is short (2.490(2) A) compared with that in 3 (2.52
isolation of 5 from solutions containing both 3 and py
suggests that electron transfer in disproportionation and
[ I ] W. Hieber, Adu. Organomer. Chem. 8 (1970) I .
[2] G. Fachinetti, F. Del Cima, G. Sbrana, T. Funaioli. J. Organomet. Chem.
287(1985) C23.
[3] M. Y. Darensbourg, Prog. Inorg. Chem. 33 (1985) 221.
[4] C. P. Horwitz, D. F. Shriver, Adu. Organomer. Chem. 23 (1984) 219. and
references cited therein.
151 M. Schneider, E. Weiss, J. Organomet. Chem. 121 (1976) 365.
161 G. Fachinetti, G. Fochi, T. Funaioli, P. F. Zanazzi, J . Chem. Soc. Chem
Commun. 1987. 89.
[7] G. Fachinetti, G. Fochi, T. Funaioli, J. Organomer. Chem. 301 (1986)
[S] Pjridine (1.5 mL, 18.6 mmol) in 100 mL of n-hexane was added dropwise to a stirred solution of 3 (6.6 g, 19.3 mmol) in 500 mL of n-hexane.
Simultaneously with gas evolution, 4 starts to precipitate immediately as
a carmine microcrystalline solid. At the end of the addition, the solid
was collected and washed with 25 m L of n-hexane. Yield: 4.25 g (60V0).
[9] 4 : triclinic crystals, P i , u = 16.910(3), h = 13.171(3), c = 12.125(3) A,
a = 104.80(2).fl=97.45(2), y = 108.95(2)", V ~ 2 4 0 1 . 7 Z = 2 . The structure was solved by direct methods using the SIR package (G. Cascarano,
C. Giacovazzo, M. C. Burla, A. Nunzi, G. Polidori, M. Camalli. R. Spagna, D. Viterbo, lXth European Crystallographic Meeting, Torino 1985,
Abstracts 1-046) and refined by the full-matrix least-squares method
with the SHELX-76 program. To avoid a too high number of parameters, the pyridiae rings were constrained to perfect hexagons with an
edge of 1.395 A and refined as rigid groups. The hydrqgen atoms were
included at the calculated positions (C-H = 1.08 A, U ~ 0 . 1 6A').
Anisotropic thermal parameters were assigned to the Co atoms only.
R = 0.059,
= 0.064
( I / ~ = ~ ' ( F , , ) + O . O 0 3 9 f i ;for
) 2837 unique reflections ( I > 3 n ( l ) ) : Philips PWI 100 single-crystal diffractometer, MokClradiation. graphite monochromator).
[lo] 5 : monoclinic crystals, P ; , / n , 0 = 2 2 699(3), h = 13.340(3), c=9.050(3)
/?=98.79(2)". V=2708.2 A'. 2 = 4 ) . The structure was solved and refined
with the procedure described in 191. The contribution of H atoms at the
calculated positions was included. with an overall isotropic thermal paAnisotropic thermal paramerers
rameter ( U ) that refined to 0.15
were refined only for C o , 0, and N atoms. R=0.048;
=0.05 I (I/w=a'(F,,) +0.0003 F i ) for
R,, =(Z w(lF,,i - lF<l)'/X wl&,l')'
2172 unique reflections (1>30(1)). Further details of the crystal structure investigation are available on request from the Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-75 14 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-52384, the
names of the authors, and the journal citation.
[II] To 3.8g ( I 1.1 mmol) of 3 dissolved in 100mL of a mixture of toluene
and n-hexane, 1.85 mL (22.9 mmol) of py was added. The solution was
kept under reduced pressure and stirred for 4 hours. Complex 5 was
obtained as an emerald-green microcrystalline solid. Yield: 4. I g (879").
1121 T. G. Richmond, Q. Shi, W. C. Trogler, F. Basolo, J . Am. Chem. SOC. 106
(1984) 76.
Alkylaluminum Cations: Synthesis and Structure
of IAl(2-C(SiMe3)2C,H4N)2jlAICI,IX*
By Lutz M. Engelhardt, Ulrich Kynast. Colin L. Ruston,*
and Allan H . White
Alkylaluminum compounds, [(AIR,)2], and alkylaluminum chlorides, [(AlR,CI),], are negligibly ionized in so-
u. Kynast,
Dr. A. H. White
Department of Physical and Inorganic Chemistry,
University of Western Australia
Nedlands, 6009 (Australia)
[*] Dr. C. L. Raston, Dr. L. M. Engelhardt, Dr.
Fig. 7 Mole~u1.11LI>\I.II \ I I U L I U I C ' 01 [ ( O C I,[ o( o(py),] * . Important distances [A] and angles ["I: c02-Co3 2.490(2). C - 0 1.14 (average), Co3-C23
1.8 16( 13). C 0 3 - C ~ ~ l . 7(average),
Co2-N 2.035 (average); CoZ-Co3-C23
175.7(4), Co2-Co3-C,, 77.9 (average), Co3-Co2-N I 12.8 (average), Co3-C,,-0
176.7 (average).
Angew. C h e m In1 Ed. Engl. 26 (1987) No. 7
We thank the Australian Research Grants Scheme for supporting this
Note added by the editorial staff A crown-ether-stabilized [AIMella
ion was reported in the May issue of Angew. Chem. (cf., however, dates
of receipt): S. G Bott, A. Alvanipour, S . D. Morley, D. A. Atwood, C.
M. Means, A. W. Coleman. J. L. Atwood, Angew. Chem. 99 (1987) 476;
Angew. Chem. Inr. Ed. Engl. 26 (1987) 485.
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pyridin, structure, synthesis, hydrocarbonic, co3, co2, ions, polarizing, co4coco, highly
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