Synthesis of novel cobalt(III) porphyrin-phosphoryl complexes

Article abstract of DOI:10.1021/om9705315

Novel porphyrinato[phosphoryl] cobalt(III) complexes were synthesized unexpectedly through the reaction of BrCo^III(por) (por = porphyrinato dianion) with Me₃SiLi (MeLi-Me₆Si₂-HMPA) and MeLi in HMPA at 78 °C. Phosphoryl complexes were also synthesized from HMPA-K and the appropriate organophosphoryl chloride-K As a result, Me₃SiLi may not always be an appropriate silylating agent for bulky organometallic electrophiles.

Full text of DOI:10.1021/om9705315

Organometallics 1998, 17, 2651-2655
2651
Syn th esis of Novel Coba lt(III) P or p h yr in -P h osp h or yl
Com p lexes
Andy K.-S. Tse, Kin Wah Mak, and Kin Shing Chan*
Department of Chemistry, The Chinese University of Hong Kong,
Shatin, New Territories, Hong Kong
Received J une 24, 1997
Novel porphyrinato[phosphoryl] cobalt(III) complexes were synthesized unexpectedly
through the reaction of BrCoIII(por) (por ) porphyrinato dianion) with Me3SiLi (MeLi-
Me6Si2-HMPA) and MeLi in HMPA at -78 °C. Phosphoryl complexes were also synthesized
from HMPA-K and the appropriate organophosphoryl chloride-K. As a result, Me3SiLi may
not always be an appropriate silylating agent for bulky organometallic electrophiles.
Ta ble 1. Abbr evia tion for P or p h yr in Com p ou n d s
In tr od u ction
R
Transition metal phosphoryl complexes are an im-
portant class of compounds due to their relevance to
catalytic hydrophosphorylation,1 catalytic C-P activa-
tion,2 potential chiral Lewis acid catalysts,3 and enzy-
matic hydrolysis of phosphodiesters.4 In the course of
attempted syntheses of cobalt porphyrin silyls5 for the
goal of measuring the bond dissociation energy using
the kinetic method developed for the coenzyme B-12 and
related models,6 we have discovered an unexpected
synthesis of novel cobalt(III) porphyrin-phosphoryl
complexes.
3,4,5-
M
Ph
p-CH3C6H4 (MeO)3C6H2
H2
Co
CoBr
CoR,
H2(tpp), 1
Co(tpp), 4
H2(ttp), 2
Co(ttp), 5
H2(ttmp), 3
Co(ttmp), 6
BrCo(tpp), 7 BrCo(ttp), 8 BrCo(ttmp), 9
RCo(tpp), 10 RCo(tpp), 11 RCo(ttmp), 12
R′ ) [PdO(NMe2)2]
Ch a r t 1
Resu lts a n d Discu ssion
The reaction of strongly nucleophilic [CoI(ttp)]- with
Me3SiCl for the synthesis of a Co-Si complex in a
manner similar to the synthesis of cobalt porphyrin-
alkyls7 did not prove to be successful (Chart 1, Table
1). The starting materials, cobalt(II) porphyrins CoII-
(tpp) (4), CoII(ttp) (5), and CoII(ttmp) (6), were conve-
niently prepared through the metalation of the corre-
sponding free base porphyrins 1-3 with Co(OAc)2 in
DMF (eq 1). When a solution of red CoII(ttp) (5) in THF
or in toluene was reduced with Na/Hg at room temper-
ature under N2 for 1 day, the brown solution of CoI(ttp)7
generated was then trapped with Me3SiCl (eq 2).
However, only CoII(ttp) was isolated.
(1) (a) Shibasaki, M.; Sasai, H.; Arai, T. Angew. Chem., Int. Ed. Engl.
1997, 36, 1237. (a) Han, L.-B. Tanka, M. J . Am. Chem. Soc. 1996, 118,
1571. (b) Uozumi, Y.; Tanahashi, A.; Lee, S.-Y.; Hayashi, T. J . Org.
Chem. 1993, 58, 1943. (c) Hirao, T.; Masunaga, T.; Ohshiro, Y.; Agawa,
T. Synthesis 1981, 56.
(2) Naazawa, H.; Matsuoka, Y.; Nakagawa, I.; Mityoshi, K. Orga-
nometallics 1992, 11, 1385.
(3) Zhou, Z.; J ablonski, C.; Bridson, J . Organometallics 1994, 13,
781.
(4) Koevari, E.; Kraemer, R. J . Am. Chem. Soc. 1996, 118, 12704.
(5) Tilley, T. D. In Chemistry of Organic Silicon Compounds; Patai,
S., Rappoport, Z., Eds.; J ohn Wiley & Sons Ltd.: New York, 1989; Vol.
2. (b) Woo, H. G.; Tilley, T. D. J . Am. Chem. Soc. 1989, 111, 8043. (c)
Woo, H. G.; Walzer, J . F.; Tilley, T. D. J . Am. Chem. Soc. 1992, 114,
7047. (d) Tilley, T. D. Acc. Chem. Res. 1993, 26, 22. (e) Levy, C. J .;
Pudaphett, R. J . Organometallics 1995, 14, 5019.
(6) (a) Halpern, J . Polyhedron 1988, 7, 1483. (b) Martin, B. D.; Finke,
R. G. J . Am. Chem. Soc. 1992, 114, 585. (c) Sirovatka, J . M.; Finke, R.
G. J . Am. Chem. Soc. 1997, 119, 3057.
(7) (a) Kobayashi, H.; Hara, T.; Kaizu Bull. Chem. Soc. J pn. 1972,
45, 2148. (b) Ogoshi, H.; Watanabe, E.-I.; Koketsu, N.; Yoshida, Z.-I.
Bull. Chem. Soc. J pn. 1976, 49, 2529. (c) Whitlock, H. W., J r.; Bower,
B. K. Tetrahedron Lett. 1965, 52, 4827. (d) Clarke, D. A.; Dolphin, D.;
Grigg, R.; J ohnson, A. W.; Pinnock, H. A. J . Chem. Soc. C 1968, 881.
(e) Dolphin, D.; Halko, D. J .; J ohnson, E. Inorg. Chem. 1981, 20, 4348.
Synthesis of cobalt porphyrin-silyls was then at-
tempted via the reaction of electrophilic cobalt(III)
porphyrin bromides with Me3SiLi, but the cobalt phos-
phoryl complexes were unexpectedly formed. The co-
S0276-7333(97)00531-1 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 05/21/1998

2652 Organometallics, Vol. 17, No. 12, 1998
Tse et al.
Ta ble 2. P r ep a r a tion of CoIII(p or )[P dO(NMe2)2]
10-12 fr om Me6Si2/MeLi (Eq 4)
containing a Co-P σ bond, such as the cobalt-phos-
phinediyl complex13a (Co-P bond length ) 2.163-2.210
Å) and the cobalt-phosphido complex13b (Co-P bond
length ) 2.244 Å). This lengthening may due to the
bonding of the phosphoryl ligand of 9 to a more sterically
bulky porphyrin ligand. Both the IR and 31P NMR data
are consistent with the proposed structure. The IR
spectrum showed a sharp PdO stretching at 1353 cm-1
(compared with υPdO ) 1296 cm-1 in HMPA).14 In the
31P NMR spectrum, a broad singlet appeared at 6.95
ppm, confirming the presence of the phosphorus atom.
Complexes of the cobalt macrocyclic phosphine con-
taining a phosphine-donating Co-P dative bond have
been recognized for many years.15,16 Metalloporphyrin
complexes such as (triphenylphosphine)(tetrakis(p-chlo-
rophenyl)porphyrinato)cobalt(II) were prepared by ad-
dition of PPh3 to the corresponding cobalt porphyrin in
PhCN.15a,b Other examples of cobalt-phosphine com-
plexes are (triphenylphosphine)(10-phenyl-2,3,7,8,12,-
13,17,18-octamethylcorrolato)cobalt(III)16 and (triphen-
ylphosphine)-(5,10,15-triphenyl-2,3,7,8,12,13,17,18- octa-
methylcorrolato)cobalt(III) (Co-P ) 2.205 Å).17 The
Co-P bond length resembles that in other cobalt-
phosphine compounds.12a Ligands of type R-PdO are
present in complexes only and attempts at isolating
them in the free state result in oligomers.18 An unusual
characteristic of the novel complex 10 is the bonding of
a PV phosphoryl ligand to the cobalt(III) porphyrin
which is the only metalloporphyrin containing a cova-
lent cobalt-phosphorus σ bond though other non-
porphyrin complexes have been characterized.3 The
yields of the corresponding cobalt(III) porphyrin-phos-
phoryls 10-12 are summarized in Table 2.
CoIII(por)-
[PdO(NMe2)2]
por
CoII(por)
tpp
ttp
10, 62%
11, 73%
4, 28%
5, 25%
ttmp
12, 91% 6 7%
balt(III) porphyrin bromides were prepared from the
aerobic oxidation of CoII(por) with aqueous HBr (48%)
in a solvent mixture of CHCl3/MeOH (1:1 v/v) at room
temperature for 2 h in 84-92% yield, respectively (eq
3).8 An orange solution of Me3SiLi was generated by
the cleavage of Me3SiSiMe3 with ethereal MeLi in
hexamethylphosphoramide (HMPA) at 0 °C under N2.9
Following the Goff10 procedure, BrCo(por) compounds
7-9 were reacted with Me3SiLi in toluene at -78 °C,
and the solution was warmed slowly to 0 °C (eq 4, Table
2). The reaction mixture produced two fractions, ac-
cording to the TLC analysis: one was identified as a
CoII(por) and the other was new compounds. After
chromatographic separation, the new compounds were
isolated.
This unexpected synthesis of the cobalt(III) porphy-
rin-phosphoryl raised the question whether the Me3SiLi
had been indeed generated. Me3SiLi is a versatile
silylating agent and can be generated conveniently. To
confirm this, Me3SiSiMe3 was reacted with the ethereal
MeLi in HMPA at 0 °C.9 The precedented reaction of
Me3SiLi with 2-cyclohexen-1-one, followed by trapping
with MeI, was repeated to yield the trans-3-trimethyl-
silyl-2-methylcyclohexanone 13, in 96% (eq 5), which
From the reaction of BrCo(tpp), the product exhibited
sharp proton resonances supporting the formation of a
diamagnetic Co(III) compound. Two resonances at δ
-0.30 and -0.27 ppm appeared with each equal to three
hydrogens, suggesting two nonequivalent methyl groups.
This was further confirmed by a signal at δ 35.00 ppm
in the 13C NMR spectrum. All other Co(por) derivatives
also show similar spectral characteristics. Therefore,
it seems unlikely the Me3Si group had been introduced
as it would have been a simple singlet.
1
was confirmed by its H NMR and mass spectra after
isolation.9 This firmly supported that Me3SiLi had
indeed been successfully generated.
The structure of 10 was finally elucidated from a
single-crystal X-ray diffraction analysis and was shown
to be (5,10,15,20-tetraphenylporphyrinato[bis(dimethyl-
amino)phosphoryl]cobalt(III) with the Co atom bounded
to a phosphoryl ligand instead of the desired silyl lig-
and.3,11 The Co-P bond length is 2.265 Å which lies in
the range of reported Co-P bond lengths12 and is longer
by 0.021-0.102 Å compared with those compounds
(8) (a) Sakurai, T.; Yamamoto, K.; Naito, H.; Nakamoto, N. Bull.
Chem. Soc. J pn. 1976, 49, 3042. (b) Datta-Gupta, N.; Bardos, T. J . J .
Pharm. Sci. 1968, 57, 300. (c) Datta-Gupta, N. J . Inorg. Nucl. Chem.
1971, 33, 219. (d) Chapman, R. D.; Fleischer, E. B. J . Am. Chem. Soc.
1982, 104, 1582. (e) J i, L.; Liu, M.; Hsieh, A. K.; Hor, R. S. A. J . Mol.
Catal. 1991, 70, 247.
(13) (a) Burt, J . C.; Boese, R; Schmid, G. J . Chem. Soc., Dalton
Trans. 1978, 1387. (b) Rayn, R. C.; Dahl, L. F. J . Am. Chem. Soc. 1973,
97, 6904.
(14) Pouchert, C. J . In The Aldrich Library of FT-IR Spectra; Aldrich
Chemical Co., Inc.: Milwaukee, WI, 1985; Vol. 1, p 921.
(15) (a) Wayland, B. B.; Abd-Elmageed, M. E. J . Am. Chem. Soc.
1974, 96, 4809. (b) Wayland, B. B.; Sherry, A. E.; Bunn, A. G. J . Am.
Chem. Soc. 1993, 115, 7675. (c) Walker, F. A. Tetrahedron Lett. 1971,
4949.
(16) Paolesse, R.; Licoccia, S.; Fanciullo, M.; Morgante, E.; Boschi,
T. Inorg. Chim. Acta. 1993, 203, 107.
(17) Paolesse, R.; Licoccia, S.; Bandoli, G.; Dolmella, A.; Boschi, T.
Inorg. Chem. 1994, 33, 1171.
(9) Still, W. C. J . Org. Chem. 1976, 41, 3063.
(10) Kim, Y. O.; Goff, M. J . Am. Chem. Soc. 1988, 110, 8706.
(11) Tse, A. K.-S.; Wong, R.-J .; Mak, T. C. W.; Chan, K. S. J . Chem.
Soc., Chem. Commun. 1996, 173.
(12) (a) Orpen, G.; Brammer, L.; Allen, F. H.; Kennard, O.; Waston,
D. G.; Taylor, R. J . Chem. Soc., Dalton Trans. 1989, S1. (b) Fenske,
D.; Basoglu, R.; Hachgenei, J .; Rogel, E. Angew. Chem., Int. Ed. Engl.
1984, 23, 160. (c) Simon, G. L.; Dahl, L. F. J . Am. Chem. Soc. 1973,
75, 2175.
(18) Henckel, G.; Niecke, E.; Engelmann, M.; Zorn, H.; Krebs, B.
Angew. Chem., Int. Ed. Engl. 1980, 19, 710.

Synthesis of Co(III) Porphyrin-Phosphoryl Complexes
Organometallics, Vol. 17, No. 12, 1998 2653
The possibility of the reaction of HMPA with Me3SiLi
was thus suspected. It has been recognized that HMPA
is an outstanding solvent for a wide variety of trans-
formations including nucleophilic substitution, â-elim-
ination, Birch-type reduction, and certain oxidations. It
has been generally accepted that HMPA is stable to
most basic reagenta, and even strongly basic reagents
like alkali amides19 and Grignard20 reagents have been
routinely employed as the metalating agents in HMPA.
However, HMPA is not stable toward the organolithium
or organopotassium and can be cleaved by n-BuLi21 or
metallic K22 to yield the bis(dimethylamino)phosphoryl
anion.
When we followed the procedure of Kaiser,21 the
phosphoryl anion (Me2N)2(O)PLi was generated by the
reaction of MeLi with HMPA in THF at 0 °C under N2.
BrCo(ttp) (8) in THF was then added to the (Me2N)2-
(O)PLi solution at -78 °C (eq 6), and the mixture was
warmed to 0 °C in 1 h. After chromatographic purifica-
tion, the cobalt(III) porphyrin-phosphoryl complex 11
was isolated and was confirmed to be identical in its
1H NMR spectrum to the complex obtained from the
reaction of 6 with Me3SiLi-HMPA.
8 Hz).23 Magnetical nonequivalence due to hindered
rotation about the P-N bond is unlikely because the
chemical shifts of the two signals of 11 in benzene-d6
remained the same from 298 to 333K. Compared with
the proton resonance of the HMPA (2.38 ppm), it is high-
field shifted by about 2.5 ppm, mainly due to the
porphyrin ring current effect. The carbon chemical
shifts of the bis(dimethylamino) group show a singlet
which indicates these carbons are magnetically equiva-
lent. The chemical shifts of the bis(dimethylamino)
carbons in 10, 11, and 12 are nearly the same, ranging
from δ 35.00 to 35.09 ppm and shifted slightly upfield
by 1.60 ppm compared with that of HMPA (δ 36.60
ppm).
The reason for successful reaction of Me3SiLi with
organic electrophiles such as cyclohexenone but not with
organometallic electrophiles such as cobalt porphyrin
bromides presumably has both steric and electronic
origins. Cyclohexenone is sterically less hindered and
harder to reduce than cobalt porphyrin bromides in
which the cobalt atom has easily accessible oxidation
The IR stretching frequency of PdO bond in 10-12
and 15 appears at 1352-1360 cm-1 (υPdO ) 1296 cm-1
in HMPA).14 It is possible that the bond order of the
P-O bond in cobalt(III) porphyrin-phosphoryls is
higher than that in HMPA since the phosphorus atom
bonds to a more electron-deficient cobalt(III) resulting
in less resonance stabilization than that of HMPA.
In conclusion, we have discovered a convenient method
of synthesizing cobalt porphyrin-phosphoryl complexes
from the reactions of alkyl lithium-HMPA with cobalt
porphyrin bromides. The observation indicated that the
use of Me3SiLi-HMPA as a silylating agent for a bulky
organometallic electrophile may not always be appropri-
ate.
states of CoI, CoII, and CoIII
.
HMPA was also cleaved by metallic K in THF to give
a yellow solution of (Me2N)2(O)PK, which reacted with
BrCo(ttp) 6 at -78 °C (eq 7) giving 10 in 64% yield (eq
6). Generation of phosphoryl anions was also successful
via the reaction of (EtO)2(O)PCl (14) with potassium
metal. Reaction of the resulting (EtO)2(O)P- anions
with BrCo(ttp) (8) at -78 °C yielded complex 15 in 58%
yield (eq 8). According to the above evidence, HMPA is
cleaved by RLi (Me3SiLi or MeLi) to give (Me2N)2(O)PLi.
The mechanism of this reaction is an 1,2-elimination of
the R-amino proton of HMPA by RLi to give gaesous
methane and N-methylimine and the phosphoryl anion
(eq 9).21
Exp er im en ta l Section
UV-vis spectra were recorded on a Hitachi U-3300 spec-
trophotometer using CH2Cl2 as the solvent. IR spectra were
recorded on a Perkin Elmer 1600 FT-IR spectrometer as a neat
film on NaBr plates. 1H NMR spectra were recorded on a
Bruker WM 250 (250 MHz) or a Bruker AMX 500 (500 MHz)
spectrometer. Chemical shifts (δ) are reported with reference
to the residual CHCl3 (δ 7.24 ppm) in CDCl3, and the coupling
constants (J ) are reported in Hertz (Hz). 13C NMR spectra
were obtained on either a Bruker WM 250 (62.9 MHz) or
Bruker AMX 500 (125 MHz) spectrometer and referenced to
the residual CHCl3 (δ 77.00 ppm) in CDCl3. 31P NMR spectra
were recorded on a Bruker AMX 500 (202 MHz) spectrometer,
and the chemical shift (δ) was referenced to the external
standard H3PO4 (0 ppm). FABMS spectra were recorded on a
J oel J MS-HX 110 mass spectrometer using m-nitrobenzyl
alcohol (NBA) as the matrix at National Tsing-Hua University,
It is instructive to gain some insight into these novel
cobalt(III) porphyrin-phosphoryls 10-12. According to
the 1H NMR spectra the two distinctive signals at
around zero ppm correspond to the bis(dimethylamino)
protons with spin-splitting by a phopshorus atom (J ∼
(19) (a) Normant, H.; Cuvigny, T. Bull. Soc. Chim. Fr. 1965, 10,
1867. (b) Romesberg, F. E.; Gilchrist, J . H.; Harrison, A. T.; Fuller, D.
J .; Collum, D. B. J . Am. Chem. Soc. 1991, 113, 5751. (c) Reich, H. J .;
Green, D. P. J . Am. Chem. Soc. 1989, 111, 8729.
(20) Normant, H.; Cuvigny, T. Bull. Soc. Chim. Fr. 1964, 9, 2004.
(21) Kaiser, E. M.; Petty, J . D.; Solter, L. E. J . Organomet. Chem.
1973, 61, C4.
(23) Simon, P. C. S. Tables of Spectral Data for Structure Determi-
nation of Organic Compounds, 2nd ed.; Springler-Verlag: New York,
1989.
(22) (a) Normant, H. Angew. Chem., Int. Ed. Engl. 1967, 6, 1046.
(b) Normant, J . F. Bull. Soc. Chim. Fr. 1966, 11, 3601.

2654 Organometallics, Vol. 17, No. 12, 1998
Tse et al.
Taiwan. Elemental Analyses were performed by Medac Ltd.,
Department of Chemistry, Brunel University, United King-
dom.
11 was obtained as a red solid (0.081 g, 73%). Rf ) 0.08 (3:1
CH2Cl2:acetone. 1H NMR (CDCl3, 250 MHz) δ -0.34 (d, 12
H, J ) 8.6 Hz), 2.64 (s, 12 H), 7.48 (d, 8 H, J ) 7.8 Hz), 7.95
(d, 8 H, J ) 7.8 Hz), 8.82 (s, 8 H); 13C NMR (CDCl3, 62.9 MHz)
δ 21.48, 35.01, 122.09, 127.61, 132.65, 133.23, 137.31, 138.91,
146.38; gate decoupling 13C NMR (C6D6, 125.8 MHz) δ 22.15
(J C-H ) 126.4 Hz), 36.06 (q, J C-H ) 136.7 Hz), 123.30 (d, J C-H
Unless otherwise noted, all materials were obtained from
commercial suppliers and used without further purification.
Tetrahydrofuran (THF) and toluene were distilled from the
sodium benzophenone ketyl and sodium, respectively, im-
mediately prior to use. HMPA was distilled from CaH2.
Me3SiCl was distilled from CaH2, stored in a Telfon-stoppered
round-bottomed flask, and degassed by the freeze-pump-
thaw method (three cycles) immediately prior to use. Silica
gel (70-230 mesh) was used for column chromatography.
Thin-layer chromatography (TLC) was performed on Merck
precoated silica 60F254 plates.
) 156.6 Hz), 133.65 (d, J C-H ) 133.7 Hz), 134.30 (d, J C-H
)
173.9 Hz), 138.07, 140.31, 145.68; 31P NMR (CDCl3, 202 MHz)
11.47; UV-vis (CH2Cl2), λmax, nm (log ꢀ) 410 (5.18), 531 (4.14);
IR (thin film) 3022, 2921, 1352, 780 cm-1; FABMS m/z 863
(M+ + 1). Anal. Calcd for C52H48CoN6OP‚H2O: C, 70.90; H,
5.72; N, 9.54; P, 3.52. Found: C, 71.29; H, 5.69; N, 9.46; P,
3.98.
5,10,15,20-Tetr a k is(3,4,5-tr im eth oxyp h en yl)p or p h yr i-
n a to[bis(d im eth yla m in o)p h osp h or yl]coba lt(III) (Me2N)2-
P (O)Co(ttm p ) (12). A solution of BrCo(ttmp) (7, 0.10 g, 0.09
mmol) in THF (10 mL) was added to the Me3SiLi [HMDS (0.36
g, 2.5 mmol)/HMPA (2 mL)/MeLi (1.43 mL, 1.5 mmol)] at -78
°C in THF (10 mL) under N2 and was warmed slowly to 0 °C
to give 12 as a red solid (0.96 g, 91%). Rf ) 0.22 (3:1 CH2Cl2/
acetone. 1H NMR (CDCl3, 250 MHz) δ -0.27 (s, 12 H, J ) 8.9
Hz), 3.92 (s, 24 H), 4.12 (s, 12 H), 7.31 (s, 8 H), 8.94 (s, 8 H);
13C NMR (CDCl3, 62.9 MHz) δ 35.09, 56.55, 61.32, 111.98,
122.09, 132.99, 137.21, 138.20, 146.43, 151.97; 31P NMR
(CDCl3, 202 MHz) 8.76; UV-vis (CH2Cl2), λmax, nm (log ꢀ)
Coba lt(III) Tetr a p h en ylp or p h yr in Br om id e Br Co(tp p )
(7).8a To a solution of the Co(tpp) (4, 0.30 g, 0.44 mmol) in
CHCl3/MeOH (200 mL, 1:1) was added aq HBr (48%, 2 mL).
The mixture was stirred at room temperature for 2 h to give
a red solution. CHCl3 (50 mL) was added, and the mixture
was washed with water (100 mL) and dried (MgSO4). The
mixture was evaporated to dryness to give a purple residue.
The residue was recrystallized from CHCl3 and petroleum
ether (bp 40-60 °C) to yield a purple solid (0.31 g, 92%). Rf )
0.30 (5% MeOH in CHCl3 v/v).
Cob a lt (III) Tet r a t olylp or p h yr in Br om id e Br Co(t t p )
(8).8b,c Co(ttp) (5, 0.30 g, 0.41 mmol) and aqueous HBr (48%,
2 mL) were stirred in CHCl3/MeOH for 2 h to give a purple
solid 6 (0.28 g, 0.35 mmol, 86%). Rf ) 0.25 (5% MeOH in
CHCl3 v/v). 1H NMR (CDCl3, 250 MHz) δ 2.63 (s, 12 H), 7.50
(brs, 8 H), 8.04 (brs, 8 H), 8.74 (s, 8 H).
413(5.15), 531 (4.07); IR (thin film) 2936, 2836, 1361, 762 cm-1
;
FABMS m/z 1166 (M+). Anal. Calcd for C60H66CoN6O13P‚H2-
O: C, 60.09; H, 5.78; N, 7.08; P, 2.61. Found: C, 60.56;H,
5.48; N, 6.59; P, 2.52.
P r ep a r a tion of tr a n s-3-Tr im eth ylsilyl-2-m eth ylcyclo-
h exa n on e (13).9 A solution of Me6Si2 (0.50 mL, 2.50 mmol)
in anhydrous HMPA (2 mL) was cooled to 0 °C under N2.
Ethereal MeLi (1.25 mL, 2 mmol) was added via syringe, and
the resulting orange solution was stirred for 15 min. THF (10
mL) was added, and the solution was immediately cooled to
-78 °C. A solution of cyclohexenone (0.144 g, 1.50 mmol) in
THF (1 mL) was then added dropwise. After stirring an
additional 15 min, MeI (0.50 mL) was injected and the mixture
was poured into pentane (50 mL) and thoroughly washed with
water (2 × 25 mL) to remove HMPA. The organic fraction
was dried (MgSO4), and after removal of the solvent, a light
yellow oil of 13 was isolated (0.265 g, 96%). 1H NMR (CDCl3,
250 MHz) δ 0.13 (s, 9H), 1.04 (d, 3 H, J ) 6.7 Hz), 1.03-2.40
(m, 8 H); MS (70 eV) 184 (1), 183 (11), 155 (30), 75 (100), 74
(19), 73 (100), 67 (12).
P r ep a r a tion of 11 fr om Rea ction of HMP A a n d MeLi.
To a solution of HMPA (0.41 g, 2.3 mmol) in THF (5 mL) at 0
°C was added MeLi in hexane (1.6 M, 1.44 mL, 2.3 mmol) via
a syringe under N2. The solution was stirred for 30 min to
give a yellow solution and was cooled to -78 °C. A solution of
BrCo(ttp) (8) in THF (10 mL) was added via cannula under
N2. It was then warmed up to 0 °C and poured into pentane
(50 mL). The mixture was thoroughly washed with H2O (50
mL × 2) and dried (MgSO4). After removal of the solvent, the
red residue was chromatographed over silica gel with CH2Cl2
as eluent to give the Co(ttp) (15%) and then with a solvent
mixture of CH2Cl2/MeOH (95:5) as the eluent to obtain the
red fraction. The solvent was removed to give 11 as a red solid
(0.057 g, 52%). Rf ) 0.08 (3:1 CH2Cl2/acetone. It was identical
in spectral characteristics and Rf with that prepared from
Me6Si2/MeLi/HMPA.
Coba lt(III) Tetr a k is(3,4,5-tr im eth oxyp h en yl)p or p h y-
r in Br om id e Br Co(ttm p ) (9).8d Co(ttmp) (3, 0.30 g, 0.29
mmol) and aqueous HBr (48%, 2 mL) were stirred in (1:1 v/v)
CHCl3/MeOH for 2 h to give 7 as a purple solid (0.29 g, 0.27
mmol, 92%). Rf ) 0.21 (5% MeOH in CHCl3). 1H NMR (CDCl3,
250 MHz) δ 3.94 (s, 24 H), 4.14 (s, 12 H), 7.42 (d, 8 H), 8.87 (s,
8 H).
5,10,15,20-Tetr a p h en ylp or p h yr in a to[bis(d im eth yla m i-
n o)p h osp h or yl]coba lt(III) (Me2N)2P (O)Co(tp p ) (10). To
a solution of hexamethyldisilane (0.36 g, 2.5 mmol) in HMPA
(2.0 mL) at 0 °C under N2 was added an ethereal solution of
MeLi (1.6 M, 1.43 mL, 1.5 mmol) was added via a syringe to
give an orange solution, and the reaction was stirred for 15
min. Freshly distilled THF (10 mL) was then added, and the
solution was cooled to -78 °C. A solution of BrCo(tpp) (7 0.10
g, 0.13 mmol) in freshly distilled THF (10 mL) was added
dropwise via a cannula. The mixture was allowed to warm to
0 °C slowly for 1 h and was poured into pentane (50 mL). It
was then washed with water (50 mL × 2) and dried (MgSO4).
After removal of the solvent, the red residue was chromato-
graphed over silica gel using CH2Cl2 as the eluent to give the
Co(tpp) 4 (28%) and 5% MeOH in CH2Cl2 (v/v) as eluent to
elute the red product fraction. The solvent was removed to
give a red solid. The solid was recrystallized by a mixture of
CH2Cl2/hexane to give the pure red crystals of 10 (0.067 g,
62%). Rf ) 0.24 (3:1 CH2Cl2/acetone. 1H NMR (CDCl3, 250
MHz) δ -0.28 (d, 12 H, J ) 7.9 Hz), 8.10 (brs, 8 H), 8.85 (s, 8
H); 13C NMR (CDCl3, 62.9 MHz) δ 35.02, 122.09, 126.84,
127.71, 127.93, 132.71, 132.25, 141.77, 146.26; 31P NMR
(CDCl3, 202 MHz) δ 6.95 (line width ) 1096 Hz); UV-vis
(CH2Cl2), λmax, nm (log ꢀ) 408 (5.22), 530 (4.17); IR (thin film)
3054, 2923, 1352, 752 cm-1; FABMS m/z 806 (M+). Anal.
Calcd for C48H40CoN6OP‚CH2Cl2: C, 66.05; H, 4.76; N, 9.44;
P, 3.84. Found: C, 66.48; H, 4.87; N, 9.23; P, 3.35.
P r ep a r a t ion of 11 fr om t h e R ea ct ion of
8 w it h
(Me2N)2(O)P K.22 To a suspension of K (0.25 g, 0.633 mmol)
in THF (10 mL) at room temperature, (Me2N)2(O)PCl (0.098
g, 0.575 mmol) was added via a syringe under N2. The yellow
mixture was stirred at room temperature for 24 h and was
chilled to -78 °C. A solution of BrCo(ttp) 8 in THF (10 mL)
was added via a cannula, and the mixture was warmed up to
0 °C slowly. The red mixture was then poured into pentane
(50 mL), washed thoroughly with H2O (50 mL × 2), and dried
5,10,15,20-Tetr atolylpor ph yr in ato[bis(dim eth ylam in o)-
p h osp h or yl]coba lt(III) (Me2N)2P (O)Co(ttp ) (11). A solu-
tion of BrCo(ttp) (8, 0.10 g, 0.128 mmol) in THF (10 mL) was
added to the Me3SiLi [Me6Si2 (0.36 g, 2.5 mmol)-HMPA (2
mL)-MeLi (1.6 M, 1.43 mL, 1.5 mmol)] in THF (10 mL) at
-78 °C under N2, and the solution was then warmed slowly
to 0 °C for 1 h. After workup and chromatographic separation,

Synthesis of Co(III) Porphyrin-Phosphoryl Complexes
Organometallics, Vol. 17, No. 12, 1998 2655
(MgSO4). After removal of the solvent, the red residue was
chromatographed over silica gel using CH2Cl2 as the eluent
to give the Co(ttp) (20%) and then a solvent mixture of CH2Cl2/
MeOH (95:5) as eluent to give 11 as a red solid (0.042 g, 38%).
Rf ) 0.08 (3:1 CH2Cl2:/acetone). It was identical in spectral
characteristics and Rf with that prepared from Me6Si2/MeLi/
HMPA.
5,10,15,20-Tetr a tolylp or p h yr in a to(d ieth oxyp h osp h or -
yl)coba lt(III) (EtO)2(O)P Co(ttp ) (15). To a suspension of
K (0.099 g, 2.53 mmol) in THF (10 mL) at room temperature
was added (EtO)2(O)PCl (0.397 g, 2.30 mmol) via syringe under
N2. The yellow mixture was stirred at room temperature for
24 h and was cooled to -78 °C. A solution of BrCoTTP (6) in
THF (10 mL) was added via a cannula, and the mixture was
warmed up to 0 °C slowly. After chromatographic purification,
15 was isolated as a red solid (0.062 g, 58%). Rf ) 0.62 (5%
MeOH in CH2Cl2). 1H NMR (CDCl3, 250 MHz) δ -0.21 (t, 6
H, J ) 7.0 Hz), 0.64 (q, 2 H, J ) 3.3 Hz), 1.03 (q, 2 H, J ) 3.3
Hz), 2.68 (s, 12 H), 7.53 (d, 8 H, J ) 7.5 Hz), 7.99 (d, 8 H, J )
7.5 Hz), 8.94 (s, 8 H); 13C NMR (CDCl3, 62.9 MHz) δ 14.85,
21.45, 58.52, 122.38, 127.61, 132.70, 133.33, 137.41, 138.76,
146.01; 31P NMR (CDCl3, 202 MHz) 6.13; UV-vis (CH2Cl2),
λ
max, nm (log ꢀ) 410 (4.51), 526 (3.33); IR (thin film) 3024 2922,
1353, 733 cm-1; FABMS M+ m/z 864. The sample for analysis
was dried in high vacuum (0.15 Torr) at room temperature
overnight. Anal. Calcd for C52H46CoN4O3P‚H2O: C, 70.74; H,
5.48; N, 6.35; P, 3.51. Found: C, 71.56; H, 5.25; N, 6.36; P,
3.52.
Ack n ow led gm en t. We thank the Research Grants
Council of Hong Kong for financial support and the
purchase of high-field NMR spectrometers.
OM9705315