Activation of Thionitrites and Isoamyl Nitrite by Group 8 Metalloporphyrins and the Subsequent Generation of Nitrosyl Thiolates and Alkoxides of Ruthenium and Osmium Porphyrins

Article abstract of DOI:10.1021/ic970282c

Ruthenium and osmium porphyrins of the form (por)M(CO) (por = octaethylporphyrinato dianion (OEP), tetratolylporphyrinato dianion (TTP)) react with thionitrites (RSNO) and isoamyl nitrite (RONO) to give the (por)M(NO)(SR) and (por)M(NO)(OR) addition produ

Full text of DOI:10.1021/ic970282c

3876
Inorg. Chem. 1997, 36, 3876-3885
Activation of Thionitrites and Isoamyl Nitrite by Group 8 Metalloporphyrins and the
Subsequent Generation of Nitrosyl Thiolates and Alkoxides of Ruthenium and Osmium
Porphyrins
Geun-Bae Yi, Li Chen, Masood A. Khan, and George B. Richter-Addo*
Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval,
Norman, Oklahoma 73019
ReceiVed March 13, 1997X
Ruthenium and osmium porphyrins of the form (por)M(CO) (por ) octaethylporphyrinato dianion (OEP),
tetratolylporphyrinato dianion (TTP)) react with thionitrites (RSNO) and isoamyl nitrite (RONO) to give the
(por)M(NO)(SR) and (por)M(NO)(OR) addition products. Reaction of S-nitroso-N-acetyl-L-cysteine methyl ester
with (TPP)Fe(THF)2 (TPP ) tetraphenylporphyrinato dianion) gives (TPP)Fe(NO) in high yield. The related
reaction of isoamyl nitrite with [(TPP)Fe(THF)2]+ gives the nitrosyl alcohol product [(TPP)Fe(NO)(HO-i-C5H11)]+.
The solid state structures of (OEP)Ru(NO)(NACysMe-S) (NACysMe ) N-acetyl-L-cysteinate methyl ester), (TTP)-
Os(NO)(S-i-C5H11), and [(TPP)Fe(NO)(HO-i-C5H11)]+ have been determined by X-ray diffraction.
Introduction
example, RSNO is found to effect bronchodilation in a manner
independent of NO activation.9 Interestingly, nitroprusside
Nitric oxide (NO) chemistry and biochemistry received a
surge of renewed interest about a decade ago when it was
proposed that the radical species referred to as the endothelium-
derived relaxing factor (EDRF) was NO.1 It is now known that
NO activates guanylyl cyclase (GC) by binding to its heme
moiety.2 Also, the biosynthesis of NO involves the heme-
containing NO synthase, whose active site is similar to that of
cytochrome P450 and contains a (porphyrin)Fe(thiolate) group.3
Thus, it has been established that the heme group is vital in
NO biochemistry and pharmacology in both NO consumption
(by GC) and production (by NO synthase).
Thionitrites (RSNO) are a class of compounds containing the
S-nitroso functional group,4 and their pharmacological properties
are invariably linked to the chemistry and biochemistry of NO.5,6
Important questions have been raised over the last few years as
to the true identity of EDRF. While it is generally accepted
that EDRF is NO, there are a few published reports that show
some thionitrites as possessing EDRF-like properties.7-9 For
([Fe(CN)5NO]2- 10
) and other nitrovasodilators such as isoamyl
nitrite are physiologically active only in the presence of thiols,
consistent with the proposed intermediacy of RSNO.11 Some
alkyl nitrites (RONO) are also known to readily nitrosate thiols
and cysteine derivatives.12
Protein thiols may be nitrosated under physiological condi-
tions to produce S-nitroso derivatives,13 although the direct
reaction of thiols with NO to produce RSNO has been
questioned.14 The reported role of thionitrites (RSNO) as NO-
storage and NO-carrier entities in ViVo is also intriguing.
Hemoglobin is also reported to be an NO carrier by using its
cysteine groups on the protein to form RSNO groups.15
Furthermore, the ability of nitrosomethane to bind directly to
the heme of GC has also prompted the suggestion that RSNO
may actually be able to bind directly to the heme site in GC.16
It has also been suggested that one of the possible pathways
(8) Kowaluk, E. A.; Fung, H.-L. J. Pharmacol. Exp. Ther. 1990, 255,
1256. (b) Gaston, B.; Reilly, J.; Drazen, J. M.; Fackler, J.; Ramdev,
P.; Arnelle, D.; Mullins, M. E.; Sugarbaker, D. J.; Chee, C.; Singel,
D. J.; Loscalzo, J.; Stamler, J. S. Proc. Natl. Acad. Sci. U.S.A. 1993,
90, 10957.
(9) Bannenberg, G.; Xue, J.; Engman, L.; Cotgreave, I.; Molde´us, P.;
Ryrfeldt, Å. J. Pharmacol. Exp. Ther. 1995, 272, 1238.
(10) Review on the physiologically relevant chemistry of nitroprusside:
Butler, A. R.; Glidewell, C. Chem. Soc. ReV. 1987, 16, 361.
(11) Ignarro, L. J.; Lippton, H.; Edwards, J. C.; Baricos, W. H.; Hyman,
A. L.; Kadowitz, P. J.; Gruetter, C. A. J. Pharmacol. Exp. Ther. 1981,
218, 739.
(12) RONO nitrosates RSH to give RSNO: (a) Barnett, D. J.; McAninly,
J.; Williams, D. L. H. J. Chem. Soc., Perkin Trans. 2 1994, 1131. (b)
Patel, H. M. S.; Williams, D. L. H. J. Chem. Soc., Perkin Trans. 2
1990, 37. (c) Crookes, M. J.; Williams, D. L. H. J. Chem. Soc., Perkin
Trans. 2 1989, 759.
(13) (a) Simon, D. I.; Mullins, M. E.; Jia, L.; Gaston, B.; Singel, D. J.;
Stamler, J. S. Proc. Natl. Acad. Sci. U.S.A. 1996, 93, 4736. (b) Keshive,
M.; Singh, S.; Wishnok, J. S.; Tannenbaum, S. R.; Deen, W. M. Chem.
Res. Toxicol. 1996, 9, 988. (c) Park, J.-W. Biochem. Biophys. Res.
Commun. 1988, 152, 916. (d) Stamler, J. S.; Simon, D. I.; Osborne,
J. A.; Mullins, M. E.; Jaraki, O.; Michel, T.; Singel, D. J.; Loscalzo,
J. Proc. Natl. Acad. Sci. U.S.A. 1992, 89, 444. (e) Stamler, J. S.; Simon,
D. I.; Jaraki, O.; Osborne, J. A.; Francis, S.; Mullins, M.; Singel, D.;
Loscalzo, J. Proc. Natl. Acad. Sci. U.S.A. 1992, 89, 8087.
(14) (a) Goldstein, S.; Czapski, G. J. Am. Chem. Soc. 1996, 118, 3419. (b)
J. Am. Chem. Soc. 1996, 118, 6806 [Erratum].
X Abstract published in AdVance ACS Abstracts, August 1, 1997.
(1) Selected reviews on NO biology: (a) Methods in Enzymology; Packer,
L., Ed.; Academic: San Diego, CA, 1996; Vol. 268. (b) Moncada,
S.; Palmer, R. M. J.; Higgs, E. A. Pharmacol. ReV. 1991, 43, 109. (c)
Ignarro, L. J. Annu. ReV. Pharmacol. Toxicol. 1990, 30, 535.
(2) (a) Deinum, G.; Stone, J. R.; Babcock, G. T.; Marletta, M. A.
Biochemistry 1996, 35, 1540. (b) Stone, J. R.; Marletta, M. A.
Biochemistry 1994, 33, 5636. (c) Yu, A. E.; Hu, S.; Spiro, T. G.;
Burstyn, J. N. J. Am. Chem. Soc. 1994, 116, 4117. (d) Craven, P. A.;
DeRubertis, F. R. Biochem. Biophys. Acta 1983, 745, 310. (e) Craven,
P. A.; DeRubertis, F. R. J. Biol. Chem. 1978, 253, 8433.
(3) Marletta, M. A. J. Biol. Chem. 1993, 268, 12231.
(4) (a) Williams, D. L. H. Nitrosation; Cambridge University Press:
Cambridge, U.K., 1988. (b) Oae, S.; Shinhama, K. Org. Prep. Proced.
Int. 1983, 15, 165.
(5) Williams, D. L. H. Chem. Commun. 1996, 1085.
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Sci. 1995, 16, 18. (b) Upchurch, G. R., Jr.; Welch, G. N.; Loscalzo,
J. AdV. Pharmacol. 1995, 34, 343. (c) Stamler, J. S. In Current Topics
in Microbiology and Immunology; Koprowski, H., Maeda, H., Eds.;
Springer-Verlag; Berlin, 1995; Vol. 196, p 19. (d) Stamler, J. S. Cell
1994, 78, 931.
(7) (a) Mathews, W. R.; Kerr, S. W. J. Pharmacol. Exp. Ther. 1993, 267,
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S0020-1669(97)00282-6 CCC: $14.00 © 1997 American Chemical Society

Activation of Thionitrites and Isoamyl Nitrite
Inorganic Chemistry, Vol. 36, No. 18, 1997 3877
signal of the solvent employed. All couplings are in hertz. FAB mass
spectra were obtained on a VG-ZAB-E mass spectrometer. UV-vis
spectra were recorded on a Hewlett Packard Model 8452A diode array
instrument.
for the NO activation of GC is its binding to a non-heme site
followed by transfer of the NO group to the heme iron.17
Recent investigations into RSNO stability revealed that the
presence of trace Cu+ (even in distilled water) plays an
important role in RSNO decomposition catalysis.18 Thus,
removal of trace metal ions (e.g., by EDTA addition) markedly
enhances RSNO stability. This finding thus raises the question
of the role of iron and copper metal ions in RSNO pharmacol-
ogy.19
The possibility of a direct interaction of RSNO with heme
led us to investigate the chemical reactions of RSNO with
synthetic metalloporphyrins of the group 8 metals. We recently
showed that nitrosamines (N-nitroso),20 nitrosoarenes (C-ni-
troso),21 and cupferron (N-nitroso)22 compounds bind intact to
iron porphyrins. We now report the results of our work with
the related S-nitroso and O-nitroso derivatives. We show that
the latter nitroso derivatives are activated by the metal centers
in Fe, Ru, and Os porphyrins via an unusual formal trans
addition process. A preliminary report on the Ru work has been
communicated.23
Preparation of Thionitrites. N-Acetyl-L-cysteine methyl ester
(NACysMe ) N-acetyl-L-cysteinate methyl ester) was prepared by
reaction of the precursor N-acetyl-L-cysteine (Aldrich) with diaz-
omethane as previously reported.27 The S-nitroso derivative was
prepared by a published procedure.28 The preparation of the remaining
thionitrites (i-C5H11SNO and CF3CH2SNO) followed established routes
from their precursor thiols.29 The following example is representa-
tive: Isoamyl mercaptan (0.418 g, 4.011 mmol) in acetic acid (2 mL)
was treated with a solution (1 mL) of NaNO2 (0.277 g, 4.015 mmol)
in water at 0 °C. The solution turned deep red immediately. After 2
min of stirring, the red product was rapidly extracted with CH2Cl2 (20
mL) and the solution washed with aqueous NaHCO3. The IR spectrum
of i-C5H11SNO in CH2Cl2 shows a characteristic peak at 1520 cm-1
for νNO, and the UV-vis spectrum of i-C5H11SNO in CH2Cl2 shows
two characteristic maxima at 334 nm and 548 nm for the thionitrite
group.30
Preparation of (OEP)Ru(NO)(NACysMe-S) (NACysMe ) N-
Acetyl-L-cysteinate Methyl Ester). To a solid mixture of (OEP)Ru-
(CO) (0.100 g, 0.151 mmol) and S-nitroso-N-acetyl-L-cysteine methyl
ester (0.032 g, 0.155 mmol) was added CH2Cl2 (10 mL). The mixture
was stirred for 10 min, during which it turned from red to dark purple.
The solvent was then removed in vacuo, the residue was dissolved in
CH2Cl2/hexane (10 mL/5 mL), and crystals were obtained by slow
evaporation of the solvent mixture in air to give (OEP)Ru(NO)-
(NACysMe-S)‚0.4CH2Cl2 (0.103 g, 0.118 mmol, 78% isolated yield).
Anal. Calcd for C42H54O4N6RuS‚0.4CH2Cl2: C, 58.26; H, 6.32; N,
9.61; Cl, 3.25; S, 3.67. Found: C, 58.50; H, 6.38; N, 9.54; Cl, 3.06;
S, 3.59. IR (KBr, cm-1): νNO ) 1791 s; νCO ) 1755 m, 1683 m; also
2962 m, 2929 w, 2869 m, 1498 m, 1466 m, 1450 m, 1428 m, 1372 m,
1363 m, 1353 m, 1316 w, 1353 m, 1302 w, 1269 m, 1241 w, 1229 w,
1206 m, 1165 m, 1152 m, 1112 m, 1057 s, 1020 s, 992 m, 961 m, 922
w, 868 w, 839 s, 746 s, 732 s, 725 s, 713 s, 698 w, 542 m . 1H NMR
(CDCl3): δ 10.29 (s, 4H, meso-H of OEP), 5.28 (s, 0.8H, CH2Cl2),
4.17 (m, 16H, CH2CH3 of OEP), 2.88 (s, 3H, OCH3 of NACysMe),
2.39 (br d, J ) 7, 1H, NHCH of NACysMe), 1.99 (t, J ) 7, 24H,
CH2CH3 of OEP), 1.48 (m (apparent q), 1H, CHNH of NACysMe),
1.19 (s, 3H, C(O)CH3 of NACysMe), -2.61 (dd, J ) 7/13, 1H, CHRHâ
of NACysMe), -3.16 (dd, J ) 5/13, 1H, CHRHâ of NACysMe). Low-
resolution mass spectrum (FAB): m/z 810 [(OEP)Ru(NACysMe-S)]+
(18%), 664 [(OEP)Ru(NO)]+ (100%), 634 [(OEP)Ru]+ (50%).
Preparation of (OEP)Ru(NO)(SCH2CF3). To a stirred CH2Cl2 (5
mL) solution of (OEP)Ru(CO) (0.030 g, 0.045 mmol) was added excess
CF3CH2SNO (> 10 equiv) in CH2Cl2 (5 mL). The mixture was stirred
for 10 min, and the solvent was then removed in vacuo. Analysis of
the residue by IR and 1H NMR spectroscopy showed quantitative
formation of the previously reported (OEP)Ru(NO)(SCH2CF3)
compound.20b
Experimental Section
All reactions were performed under an atmosphere of prepurified
nitrogen using standard Schlenk glassware and/or in an Innovative
Technology Labmaster 100 dry box. Solutions for spectral studies were
also prepared under a nitrogen atmosphere. Solvents were distilled
from appropriate drying agents under nitrogen just prior to use: CH2-
Cl2 (CaH2), toluene (Na), and hexane (Na/benzophenone/tetraglyme).
Anhydrous deaerated methanol was purchased from Aldrich Chemical
Co. and used as received.
Chemicals. (TTP)Ru(CO)24 and (TTP)Os(CO)25 were prepared by
26
reaction of TTPH2 with Ru3(CO)12 (Strem) and Os3(CO)12 (Strem),
respectively (TTP ) 5,10,15,20-tetra-p-tolylporphyrinato dianion).
(TPP)FeCl (TPP ) 5,10,15,20-tetraphenylporphyrinato dianion), (OEP)-
Ru(CO) (OEP ) 2,3,7,8,12,13,17,18-octaethylporphyrinato dianion),
isoamyl nitrite (i-C5H11ONO, 97%), 2,2,2-trifluoroethanethiol (95%),
and isoamyl mercaptan (i-C5H11SH, 97%) were purchased from Aldrich
Chemical Co. Chloroform-d (99.8%, Cambridge Isotope Laboratories)
was vacuum-distilled from CaH2 under nitrogen prior to use. Elemental
analyses were performed by Atlantic Microlab, Norcross, GA. Nitric
oxide (98%, Matheson Gas) was passed through KOH pellets and a
cold trap (dry ice/acetone, -78 °C) to remove higher nitrogen oxides.
Instrumentation. Infrared spectra were recorded on a Bio-Rad FT-
155 FTIR spectrometer. Proton NMR spectra were obtained on a
Varian XL-300 spectrometer and the signals referenced to the residual
(16) Stone, J. R.; Marletta, M. A. Biochemistry 1995, 34, 16397.
(17) Stone, J. R.; Marletta, M. A. Biochemistry 1996, 35, 1093.
(18) McAninly, J.; Williams, D. L. H.; Askew, S. C.; Butler, A. R.; Russell,
C. J. Chem. Soc., Chem. Commun. 1993, 1758.
(19) (a) Dicks, A. P.; Swift, H. R.; Williams, D. L. H.; Butler, A. R.; Al-
Sa’doni, H. H.; Cox, B. G. J. Chem. Soc., Perkin Trans. 2 1996, 481.
(b) Dicks, A. P.; Williams, D. L. H. Chem. Biol. 1996, 3, 655. (c)
Askew, S. C.; Barnett, D. J.; McAninly, J.; Williams, D. L. H. J. Chem.
Soc., Perkin Trans. 2 1995, 741. (d) Gordge, M. P.; Meyer, D. J.;
Hothersall, J.; Neild, G. H.; Payne, N. N.; Noronha-Dutra, A. Brit. J.
Pharmacol. 1995, 114, 1083. (e) Williams, D. L. H. Transition Met.
Chem. (London) 1996, 21, 189.
(20) (a) Yi, G.-B.; Khan, M. A.; Richter-Addo, G. B. J. Am. Chem. Soc.
1995, 117, 7850. (b) Yi, G.-B.; Khan, M. A.; Richter-Addo, G. B.
Inorg. Chem. 1996, 35, 3453.
(21) Wang, L.-S.; Chen, L.; Khan, M. A.; Richter-Addo, G. B. Chem.
Commun. 1996, 323.
Preparation of (TTP)Ru(NO)(O-i-C5H11). A CH2Cl2 solution (10
mL) of (TTP)Ru(CO) (0.100 g, 0.029 mmol) and i-C5H11ONO (0.50
mL, ca. 3.6 mmol) was stirred at reflux for 10 min, during which the
mixture turned from red to reddish brown. The solvent was removed
in vacuo, the residue was redissolved in CH2Cl2 (10 mL), and the
solution was filtered through a column of neutral alumina (1.5 × 15
cm). The volume of the filtrate was reduced to ca. 5 mL, and a mixture
of hexanes (5 mL) was added. Crystals were obtained by slow
evaporation of the solvent mixture at room temperature in air to give
(TTP)Ru(NO)(O-i-C5H11)‚0.5CH2Cl2 (0.065 g, 0.070 mmol, 58%
isolated yield).
Anal. Calcd for C53H47O2N5Ru‚0.5CH2Cl2: C, 69.13; H, 5.20; N,
7.53; Cl, 3.82. Found: C, 68.80; H, 5.32; N, 7.53, Cl, 3.93. IR (KBr,
(22) Yi, G.-B.; Khan, M. A.; Richter-Addo, G. B. Inorg. Chem. 1995, 34,
5703.
(23) Yi, G.-B.; Khan, M. A.; Richter-Addo, G. B. Chem. Commun. 1996,
2045.
(24) Rillema, D. P.; Nagle, J. K.; Barringer, L. F., Jr.; Meyer, T. J. J. Am.
Chem. Soc. 1981, 103, 56.
(25) Che, C.-M.; Poon, C.-K.; Chung, W.-C; Gray, H. B. Inorg. Chem.
1985, 24, 1277.
(26) Adler, A. D.; Longo, F. R.; Finarelli, J. D.; Goldmacher, J.; Assour,
J.; Korsakoff, L. J. Org. Chem. 1967, 32, 476.
(27) Kupchan, S. M.; Giacobbe, T. J.; Krull, I. S.; Thomas, A. M.; Eakin,
M. A.; Fessler, D. C. J. Org. Chem. 1970, 35, 3539.
(28) Bonnett, R.; Nicolaidou, P. J. Chem. Soc., Perkin Trans. 1 1979, 1969.
(29) Roy, B.; d’Hardemare, A. d. M.; Fontecave, M. J. Org. Chem. 1994,
59, 7019.
(30) (a) Oae, S.; Shinhama, K.; Fujimori, K.; Kim, Y. H. Bull. Chem. Soc.
Jpn. 1980, 53, 775. (b) Oae, S.; Kim, Y. H.; Fukushima, D.; Shinhama,
K. J. Chem. Soc., Perkin Trans. 1 1978, 913.

3878 Inorganic Chemistry, Vol. 36, No. 18, 1997
Yi et al.
Table 1. Crystal Data and Structure Refinement Parameters
(OEP)Ru(NO)(NACysMe-S)
(TTP)Os(NO)(S-i-C5H11)
C53H47N5OSOs
992.22
188(2)
triclinic
P1
[(TPP)Fe(NO)(HO-i-C5H11)]ClO4
formula
fw
C42H54N6O4SRu
840.04
C54H39N5Cl3O6Fe
1016.10
153(2)
monoclinic
P21/c
T, K
203(2)
crystal system
space group
unit cell dimens
a, Å
monoclinic
P21
8.2810(10)
11.084(2)
11.190(2)
11.687(2)
68.80(2)
73.11(1)
83.31(1)
1292.8(4); 1
1.274
2.545
12.711(2)
19.067(5)
20.138(3)
90
96.76(1)
90
4847(2); 4
1.393
0.533
b, Å
19.455(3)
c, Å
12.670(2)
R, deg
90
90.71(1)
90
2041.1(5); 2
1.367
0.484
880
â, deg
γ, deg
V, Å3; Z
D(calcd), g/cm3
abs coeff, mm-1
F(000)
500
2092
crystal size, mm3
0.22 × 0.36 × 0.44 mm
0.58 × 0.46 × 0.32 mm
0.46 × 0.42 × 0.28 mm
θ range for data collection, deg 1.61 to 28.41
index ranges
reflns collected
2.23 to 27.00
1.93 to 25.00
0 e h e 10, 0 e k e 26, -16 e l e 16 0 e h e 14, -13 e k e 13, -14 e l e 14 0 e h e 15, 0 e k e 22, -23 e l e 23
5147
5726
8851
independent reflns
data/restraints/parameters
goodness-of-fit on F2
final R indices [I > 2σ(I)]a,b
R indices (all data)a,b
4823 [R(int) ) 0.0482]
5629 [R(int) ) 0.0331]
8435 [R(int) ) 0.0367]
4816/1/487
5612/323/552
8406/43/703
1.079
1.133
1.030
R1 ) 0.0465, wR2 ) 0.1047
R1 ) 0.0455, wR2 ) 0.1188
R1 ) 0.0493, wR2 ) 0.1335
2.172 and -1.187
R1 ) 0.0645, wR2 ) 0.1718
R1 ) 0.0923, wR2 ) 0.2213
0.731 and -0.748
R1 ) 0.0639, wR2 ) 0.1249
largest diff peak and hole, e/Å3 1.401 and -0.433
2
4
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) {∑[w(Fo - Fc2)2]/∑[wFo ]}1/2
.
cm-1): νNO ) 1809 s; also 3025 w, 2952 w, 2918 w, 2865 w, 1525 w,
1489 w, 1455 w, 1362 w, 1348 m, 1303 w, 1261 m, 1212 m, 1183 m,
1112 m, 1072 s, 1015 s, 976 w, 869 w, 847 w, 796 s, 736 m, 717 m,
711 m, 648 w, 597 m, 560 w, 521 m, 510 m, 478 w, 451 w. 1H NMR
(CDCl3): δ 8.92 (s, 8H, pyrrole H, TTP), 8.12 (app t (overlapping
d’s), 8H, o/o′-H of TTP), 7.56 (d, J ) 8, 8H, m-H of TTP), 5.28 (s,
1H, CH2Cl2), 2.70 (s, 12H, CH3 of TTP), -0.59 (d, J ) 7, 6H, (CH3)2-
CHCH2CH2O), -1.02 (m, 1H, (CH3)2CHCH2CH2O), -2.34 (t, J ) 7,
2H, (CH3)2CHCH2CH2O), -2.78 (dt, J ) 7/7, 2H, (CH3)2CHCH2-
CH2O). Low-resolution mass spectrum (FAB): m/z 887 [(TTP)Ru-
(NO)(O-i-C5H11)]+ (8%), 800 [(TTP)Ru(NO)]+ (100%), 770 [(TTP)-
Ru]+ (71%).
crystalline solid was washed with hexanes (3 × 5 mL) and dried in
vacuo for 3 h to give (TTP)Os(NO)(O-i-C5H11) (0.041 g, 0.042 mmol,
57% yield).
Anal. Calcd for C53H47O2N5Os: C, 65.21; H, 4.85; N, 7.17.
Found: C, 65.15; H, 4.93; N, 7.13. IR (KBr, cm-1): νNO ) 1770 s;
also 3024 w, 2947 w, 2918 w, 2865 w, 1806 w, 1528 w, 1512 w, 1494
w, 1455 w, 1365 w, 1351 m, 1306 w, 1214 m, 1183 m, 1110 w, 1075
m, 1018 s, 978 w, 848 w, 798 s, 719 m, 644 m, 599 w, 594 w, 523 m.
IR (CH2Cl2, cm-1): νNO ) 1766 s. 1H NMR (CDCl3): δ 8.93 (s, 8H,
pyrrole H of TTP), 8.12 (app t (overlapping d’s), 8H, o/o′-H of TTP),
7.56 (m (overlapping d’s), 8H, m/m′-H of TTP), 2.70 (s, 12H, CH3 of
TTP), -0.61 (d, J ) 7, 6H, (CH3)2CHCH2CH2O), -1.07 (m, 1H,
(CH3)2CHCH2CH2O), -2.27 (t, J ) 7, 2H, (CH3)2CHCH2CH2O), -2.82
(dt (app q), J ) 7/7, 2H, (CH3)2CHCH2CH2O). Low-resolution mass
spectrum (FAB): m/z 977 [(TTP)Os(NO)(O-i-C5H11) + H]+ (24%),
890 [(TTP)Os(NO) + H]+ (100%), 859 [(TTP)Os]+ (33%).
Reaction of (TPP)Fe(THF)2 with S-Nitroso-N-acetyl-L-cysteine
Methyl Ester. A CH2Cl2 solution (10 mL) of (TPP)Fe(THF)2 (0.080
g, 0.099 mmol)31 and S-nitroso-N-acetyl-L-cysteine methyl ester (0.021
g, 0.11 mmol) was stirred for 30 min, during which the mixture turned
from red to purple. After removal of solvent in vacuo, the residue
was redissolved in CH2Cl2 (10 mL) and MeOH (10 mL), and ca. half
the solvent was removed in vacuo. The resulting suspension was
filtered through a cotton plug, and the trapped solid was washed with
MeOH to remove any side products. The remaining purple residue on
the cotton plug was then eluted with CH2Cl2 and the filtrate collected.
Solvent removal from this filtrate gave (TPP)Fe(NO) (0.065 g, 0.093
mmol, 94% yield), identified by its characteristic IR (νNO ) 1699 cm-1
(KBr)) and UV-vis spectra (CH2Cl2: 406, 474 (sh), 538, 608 nm).32
Preparation of (TTP)Os(NO)(S-i-C5H11). A CH2Cl2 solution (10
mL) of (TTP)Os(CO) (0.100 g, 0.113 mmol) was reacted with i-C5H11-
SNO (ca. 3 mmol in 20 mL of CH2Cl2), and the mixture was stirred
for 10 h, during which its color turned from purple to brown. After
all volatiles were removed in vacuo, the residue was dissolved in a
CH2Cl2/hexane mixture (1:5, 12 mL), and the solution was transferred
to the top of an alumina column (1.5 × 15 cm) and eluted with CH2-
Cl2/hexane (ca. 50-100 mL). A resulting green band was separated
from a slow-moving brown band and collected. The solvent was
removed in vacuo and the product identified as (TTP)Os(NO)(S-i-
C5H11)‚0.3CH2Cl2 (0.023 g, 0.023 mmol, 20% isolated yield).
Anal. Calcd for C53H47ON5OsS‚0.3CH2Cl2: C, 62.90; H, 4.71; N,
6.88. Found: C, 62.99; H, 5.09; N, 6.61. IR (KBr, cm-1): νNO
)
1760 s; also 2955 m, 2921 w, 2869 w, 1574 m, 1542 w, 1516 m, 1467
w, 1352 m, 1307 w, 1275 w, 1214 w, 1181 m, 1107 w, 1072 m, 1018
s, 798 s, 764 w, 750 m, 720 w, 668 w, 525 m. 1H NMR (CDCl3): δ
8.93 (s, 8H, pyrrole H, TTP), 8.10 (app t (overlapping d’s), 8H, o/o′-H
of TTP), 7.56 (m (overlapping d’s), 8H, m/m′-H of TTP), 5.28 (s, 0.6H,
CH2Cl2), 2.70 (s, 12H, CH3 of TTP), -0.26 (d, J ) 3, 6H, (CH3)2-
CHCH2CH2S), -1.01 (m, 1H, (CH3)2CHCH2CH2S), -1.60 (m, 2H,
(CH3)2CHCH2CH2S), -2.73 (t, J ) 7, 2H, (CH3)2CHCH2CH2S). Low-
resolution mass spectrum (FAB): m/z 992 [(TTP)Os(NO)(S-i-C5H11)]+
(5%), 890 [(TTP)Os(NO) + H]+ (100%), 860 [(TTP)Os + H]+ (22%).
Preparation of (TTP)Os(NO)(O-i-C5H11). A CH2Cl2 solution (10
mL) of (TTP)Os(CO) (0.065 g, 0.073 mmol) was reacted with i-C5H11-
ONO (0.20 mL, 1.4 mmol). The solution was gently heated and left
to stir for 15 min. The color of the solution did not change very much
(from red to purplish red). All of the solvent was then removed in
vacuo. The residue was dissolved in toluene (2 mL), a mixture of
hexanes (5 mL) was added, and the resultant mixture was kept overnight
at -20 °C. The supernatant solution was discarded, and the purple
Reaction of [(TPP)Fe(THF)2]ClO4 with i-C5H11ONO. To a CH2-
Cl2 solution (10 mL) of [(TPP)Fe(THF)2]ClO4 (0.100 g, 0.114 mmol)20a
was added i-C5H11ONO (0.5 mL, ca. 4 mmol). After 30 min of stirring,
hexane (5 mL) was added to the solution, and the mixture was kept at
-20 °C for 2 weeks. The resulting crystalline precipitate was collected
and identified as [(TPP)Fe(NO)(HO-i-C5H11)]ClO4‚CH2Cl2‚H2O
(0.88 g, 0.089 mmol, 78% yield). Anal. Calcd for C49H40N5O6ClFe‚
CH2Cl2‚H2O: C, 60.71; H, 4.48; N, 7.08; Cl, 10.77. Found: C, 60.61;
H, 4.61; N, 6.50, Cl, 11.16. IR (KBr, cm-1): νNO ) 1935 s; also 1597
w, 1577 vw, 1484 w, 1466 vw, 1440 m, 1342 m, 1311 w, 1268 m,
(31) Reed, C. A.; Mashiko, T.; Scheidt, W. R.; Spartalian, K.; Lang, G. J.
Am. Chem. Soc. 1980, 102, 2302.
(32) Scheidt, W. R.; Frisse, M. E. J. Am. Chem. Soc. 1975, 97, 17.

Activation of Thionitrites and Isoamyl Nitrite
Inorganic Chemistry, Vol. 36, No. 18, 1997 3879
1227 w, 1200 m, 1177 m, 1160 vw, 1106 s, br, 1074 s, br, 1046 s, br,
1005 s, br, 925 m, 870 m, 848 w, 833 w, 801 s, 753 s, 735 s, 702 s,
662 m, 620 s, 566 m, 524 s, 461 s, 407 s. Low-resolution mass
spectrum (FAB): m/z 668 [(TPP)Fe]+ (100%). This complex is
thermally unstable in solution, slowly releasing NO.
Structural Determinations by X-ray Crystallography. All crystal
data were collected on a Siemens P4 diffractometer with Mo KR
radiation (λ ) 0.710 73 Å). The structures were solved using the
SHELXTL (Siemens) system and refined by full-matrix least squares
on F2 using all reflections (SHELXL-93). Thermal ellipsoid plots are
drawn at 35% probability.
i. (OEP)Ru(NO)(NACysMe-S). A crystal of (OEP)Ru(NO)-
(NACysMe-S) was grown from a CH2Cl2/hexane solution (1:1) left in
air overnight. The data were corrected for Lorentz and polarization
effects. No absorption correction was applied since it was judged to
be insignificant. Details of crystal data and refinement are given in
Table 1, and selected bond lengths and angles are collected in Table 2.
ii. (TTP)Os(NO)(S-i-C5H11). A crystal was grown from a saturated
solution of CH2Cl2/hexane (1:2) left for 2 d at -20 °C. Some parts of
the structure are affected by disorder. In particular, the carbon atoms
C(53), C(52), C(50), and C(49) of the axial thiolate group (S-i-C5H11)
are severely disordered as evident from the very high thermal motions
displayed by these atoms. Details of crystal data and refinement are
given in Table 1, and selected bond lengths and angles are collected in
Table 3.
iii. [(TPP)Fe(NO)(i-C5H11OH)]ClO4. A crystal was grown from
a concentrated solution of CH2Cl2/hexane (2:1) left for 2 weeks at -20
°C. The asymmetric unit contains a cation with a completely disordered
i-C5H11 group in the axial position. In addition to the cation, the
asymmetric unit also contains a disordered perchlorate anion, a
disordered dichloromethane molecule, and a disordered solvent mol-
ecule. Because of the extreme disorder of the solvent (refined as a
hydrocarbon), it was not possible to clearly identify it. The six peaks
were refined as carbon atoms with C(51) and C(52) with full occupancy
and C(53), C(54), C(55), and C(56) with 0.5 occupancy. Completely
labeled diagrams of the cation, anion, and solvent molecules are
available as Supporting Information. In the final cycles of refinement,
hydrogen atoms were included in the idealized positions for the cation.
Details of crystal data and refinement are given in Table 1, and selected
bond lengths and angles are collected in Table 4.
Figure 1. (a) Molecular structure of (OEP)Ru(NO)(NACysMe-S).
Hydrogen atoms have been omitted for clarity. (b) View along the
S(1)-Ru(1) bond showing the orientation of the axial thiolate ligand.
The ethyl substituents on the porphyrin have been omitted.
not show the parent ion but shows ion fragments due to loss of
the NO ligand (m/z 810) or loss of the cysteinate ligand (m/z
664). The sharpness of the peaks in the 1H NMR spectrum of
the complex in CDCl3 is consistent with the expected diamag-
netic nature of the formal RuII product (with the linear nitrosyl
ligand regarded as NO+).33 When the reagents of eq 1 (or
(OEP)Ru(CO) with CF3CH2SNO) are combined in CD2Cl2 in
an NMR tube and the 1H NMR spectrum is collected im-
mediately afterward, only the peaks of the nitrosyl thiolate
product are observed, indicating the quantitative nature of the
reaction.
Results
Ruthenium Complexes. Reaction of (OEP)Ru(CO) with 1
equiv of solid S-nitroso-N-acetyl-L-cysteine methyl ester in CH2-
Cl2 at room temperature results in an instantaneous color change
from red to dark purple and the replacement of the 1919 cm-1
band in the IR spectrum of the reaction mixture (due to νCO of
(OEP)Ru(CO)) with a new band at 1805 cm-1 assigned to νNO
of the nitrosyl product. The reaction generates the nitrosyl
thiolate (OEP)Ru(NO)(NACysMe-S) complex resulting from a
formal trans addition in 78% yield after workup.
In order to unambiguously determine the mode of attachment
of the multi-heteroatom cysteinate ligand in (OEP)Ru(NO)-
(NACysMe-S), we subjected a suitable crystal to a single-crystal
X-ray crystallographic analysis. The molecular structure is
shown in Figure 1. Selected bond lengths and angles are
collected in Table 2. The axial Ru-N(O) bond length is 1.790-
(5) Å, and the N-O bond length is 1.123(8) Å. The Ru-N-O
linkage is essentially linear, with a bond angle of 174.8(6)°.
The Ru-S bond length is 2.362(2) Å, and the Ru-S-C(37)
bond angle is 107.1(3)°.
(OEP)Ru(CO) + RSNO f (OEP)Ru(NO)(SR) (1)
SR ) NACysMe-S (N-acetyl-L-cysteinate methyl ester)
This product is recrystallized from CH2Cl2/hexanes in air and
is air-stable in solution and in the solid state, not showing any
signs of decomposition in the solid state for at least 2 weeks. It
is readily soluble in chlorinated solvents such as CH2Cl2 and
CHCl3 but is insoluble in hydrocarbon solvents such as hexanes
and benzene. The νNO of 1791 cm-1 (KBr) is similar to those
of other (OEP)Ru(NO)(SR) nitrosyl thiolates generated by us
previously (SR ) SCH2CF3 (1782 cm-1), SC6F4H (1798 cm-1))
from the reaction of the respective thiolate anions with [(OEP)-
Ru(NO)(H2O)]+.20b The (OEP)Ru(NO)(NACysMe-S) complex
also displays νCO bands at 1755 and 1683 cm-1 due to the
coordinated cysteinate ligand. The mass spectrum (FAB) does
The related reaction between (OEP)Ru(CO) and excess
isoamyl nitrite (i-C5H11ONO) gives a product that was very
difficult to isolate or purify (νNO 1790 cm-1 (CH2Cl2)).
However, replacement of OEP with TTP results in the successful
(33) Richter-Addo, G. B.; Legzdins, P. Metal Nitrosyls; Oxford University
Press: New York, 1992.

3880 Inorganic Chemistry, Vol. 36, No. 18, 1997
Yi et al.
Table 2. Selected Bond Lengths and Angles for
(OEP)Ru(NO)(NACysMe-S)
Bond Lengths (Å)
Ru(1)-N(5)
Ru(1)-N(2)
Ru(1)-N(3)
Ru(1)-N(1)
Ru(1)-N(4)
Ru(1)-S(1)
S(1)-C(37)
O(1)-N(5)
O(2)-C(39)
O(3)-C(41)
O(4)-C(41)
O(4)-C(42)
N(1)-C(4)
1.790(5)
2.043(4)
2.045(6)
2.057(5)
2.068(4)
2.362(2)
1.814(8)
1.123(8)
1.206(12)
1.181(10)
1.301(10)
1.420(12)
1.367(8)
N(1)-C(1)
1.382(8)
1.374(8)
1.388(8)
1.375(8)
1.380(8)
1.373(8)
1.376(8)
1.324(11)
1.431(10)
1.532(10)
1.540(11)
1.494(14)
N(2)-C(6)
N(2)-C(9)
N(3)-C(14)
N(3)-C(11)
N(4)-C(19)
N(4)-C(16)
N(6)-C(39)
N(6)-C(38)
C(37)-C(38)
C(38)-C(41)
C(39)-C(40)
Bond Angles (deg)
N(5)-Ru(1)-N(2)
N(5)-Ru(1)-N(3)
N(2)-Ru(1)-N(3)
N(5)-Ru(1)-N(1)
N(2)-Ru(1)-N(1)
94.2(3) C(37)-S(1)-Ru(1)
92.3(3) C(41)-O(4)-C(42)
90.4(2) O(1)-N(5)-Ru(1)
93.7(2) C(39)-N(6)-C(38)
89.3(2) C(38)-C(37)-S(1)
107.1(3)
115.2(9)
174.8(6)
122.1(7)
111.9(5)
110.7(6)
109.9(6)
N(3)-Ru(1)-N(1) 174.0(2) N(6)-C(38)-C(37)
N(5)-Ru(1)-N(4) 90.5(3) N(6)-C(38)-C(41)
N(2)-Ru(1)-N(4) 175.2(4) C(37)-C(38)-C(41) 106.3(6)
N(3)-Ru(1)-N(4)
N(1)-Ru(1)-N(4)
N(5)-Ru(1)-S(1)
N(2)-Ru(1)-S(1)
N(3)-Ru(1)-S(1)
N(1)-Ru(1)-S(1)
N(4)-Ru(1)-S(1)
89.7(2) O(2)-C(39)-N(6)
90.2(2) O(2)-C(39)-C(40)
177.0(2) N(6)-C(39)-C(40)
88.0(2) O(3)-C(41)-O(4)
89.6(2) O(3)-C(41)-C(38)
84.3(2) O(4)-C(41)-C(38)
87.2(2)
120.8(10)
121.6(10)
117.6(9)
124.0(9)
124.5(8)
111.3(7)
isolation of the analytically pure nitrosyl alkoxide product
(TTP)Ru(NO)(O-i-C5H11) in 58% yield after workup (eq 2).
Figure 2. IR monitoring (in CH2Cl2) of the reaction of (TTP)Ru(CO)
(labeled o in spectrum a; υCO 1934 cm-1) with isoamyl nitrite to give
(TTP)Ru(NO)(O-i-C5H11) (∆ in spectrum d; υNO 1809 cm-1). Spectrum
b: after addition of isoamyl nitrite, showing the intermediacy of (TTP)-
Ru(CO)(O-i-C5H11) (*; υCO 2006 cm-1), starting (TTP)Ru(CO), and
product (TTP)Ru(NO)(O-i-C5H11). Spectrum c: after further reaction
of the sample of spectrum b for 50 min.
(TTP)Ru(CO) + i-C5H11ONO f (TTP)Ru(NO)(O-i-C5H11)
(2)
The reaction is slower than that described in eq 1, and mild
heating is required for the reaction to proceed to completion in
a 10 min period.34 Indeed, when the reaction is run at room
temperature and monitored by IR spectroscopy, an intermediate
is seen to form (νCO 2006 cm-1 (CH2Cl2), Figure 2). This
intermediate has been tentatively assigned as the carbonyl
alkoxide (TTP)Ru(CO)(O-i-C5H11) complex (see Discussion).
The spectroscopic data for the final (TTP)Ru(NO)(O-i-C5H11)
product are entirely consistent with its formulation as a nitrosyl
alkoxide. Thus, the νNO of 1809 cm-1 is close to that recently
reported for the crystallographically characterized (TTP)Ru-
(NO)(OMe) (νNO 1800 cm-1),35 and the mass spectrum of
(TTP)Ru(NO)(O-i-C5H11) also shows a parent ion at m/z 887.
Osmium Complexes. The analogous reaction of (TTP)Os-
(CO) with isoamyl thionitrite in CH2Cl2 results in the replace-
ment of the νCO of 1899 cm-1 for (TTP)Os(CO) in its IR
spectrum with a new band at 1770 cm-1 assigned to νNO of the
formal trans-addition product (eq 3).
1770 cm-1). When all volatiles are removed from the reaction
mixture after initial RSNO addition and the residue36 redissolved
in CH2Cl2 and NO gas added, two products are formed: the
expected nitrosyl thiolate (νNO 1770 cm-1) and the nitrosyl
nitrito (TTP)Os(NO)(ONO) complex (νNO 1818 cm-1 37
as
)
shown in Figure 4. An independent reaction of authentic (TTP)-
Os(NO)(S-i-C5H11) with NO gas also produces (TTP)Os(NO)-
(ONO) quantitatively.37,38
The final nitrosyl thiolate product of eq 3 is very soluble in
benzene and in polar solvents such as CH2Cl2 and is moderately
soluble in hexanes. The product is obtained pure after chro-
matography and is isolated as an analytically pure solid in
somewhat low yield. Unlike the ruthenium analog, this
compound is air-sensitive in solution, which, together with its
high solubility, probably accounts for partial loss of product
during isolation procedures. In any event, the spectroscopic
(36) Low-resolution mass spectral data for the solid residue formulated as
(TTP)Os(CO)(S-i-C5H11): FAB+ m/z 886 [(TTP)Os(CO)]+; EI (20
eV) m/z 206 [(SC5H11)2]+ 88%, 103 [SC5H11]+ 7%, 71 [C5H11]+ 100%.
(37) Data for (TTP)Os(NO)(ONO) are as follows. IR (KBr, cm-1): νNO
(TTP)Os(CO) + i-C5H11SNO f (TTP)Os(NO)(S-i-C5H11)
(3)
1
) 1805 s; also νONO 1530, 920 cm-1. H NMR (CDCl3): δ 9.00 (s,
When the reaction described in eq 3 is performed under a
nitrogen purge and monitored by IR spectroscopy, an intermedi-
ate is seen to form (1937 cm-1, Figure 3). In the presence of
excess RSNO, the nitrosyl thiolate product is then formed (νNO
8H, pyrrole H of TTP), 8.15 (d, J ) 8, 4H, o-H of TTP), 8.05 (d, J
) 8, 4H, o′-H of TTP), 7.56 (app t (overlapping d’s), 8H, m/m′-H of
TTP), 2.67 (s, 12H, CH3 of TTP). Low-resolution mass spectral data
(FAB): m/z 905 [(TTP)Os(ONO)]+ (4%), 889 [(TTP)Os(NO)]+ (11%).
Manuscript in preparation.
(38) We and others35a,39 have reported on the synthesis of the Ru analogs:
Kadish, K. M.; Adamian, V. A.; Van Caemelbecke, E.; Tan, Z.;
Tagliatesta, P.; Bianco, P.; Boschi, T.; Yi, G.-B.; Khan, M. A.; Richter-
Addo, G. B. Inorg. Chem. 1996, 35, 1343.
(34) The expectation of a slower reaction of RONO compared with RSNO
has some precedent.12a
(35) (a) Bohle, D. S.; Goodson, P. A.; Smith, B. D. Polyhedron 1996, 15,
3147. (b) Bohle, D. S. Personal communication.
(39) Ford, P. C. Personal communication.

Activation of Thionitrites and Isoamyl Nitrite
Inorganic Chemistry, Vol. 36, No. 18, 1997 3881
Figure 4. IR monitoring (in CH2Cl2) of the reaction of (TTP)Os(CO)
(labeled o in spectrum a; υCO 1899 cm -1) with isoamyl thionitrite
followed by NO gas to eventually give (TTP)Os(NO)(ONO) (# in
spectrum d; υNO 1818 cm -1). Spectrum b: after addition of isoamyl
thionitrite while the sample was purged with N2, showing the formation
of intermediate (TTP)Os(CO)(S-i-C5H11) (*; υCO 1937 cm-1). Spectrum
c: further reaction of a CH2Cl2 solution of the dried residue from the
sample of spectrum b with NO gas to give a mixture of (TTP)Os(NO)-
(S-i-C5H11) (4; υNO 1770 cm -1) and (TTP)Os(NO)(ONO) (#; υNO 1818
cm-1).
Figure 3. IR monitoring (in CH2Cl2) of the reaction of (TTP)Os(CO)
(labeled o in spectrum a; υCO 1899 cm-1) with isoamyl thionitrite to
give (TTP)Os(NO)(S-i-C5H11) (∆ in spectrum d; υNO 1770 cm-1).
Spectrum b: after addition of isoamyl thionitrite while the sample was
purged with N2, showing the formation of intermediate (TTP)Os(CO)-
(S-i-C5H11) (*; υCO 1937 cm-1). Spectrum c: after addition of excess
isoamyl thionitrite without purging with N2, showing formation of the
(TTP)Os(NO)(S-i-C5H11) product.
properties of (TTP)Os(NO)(S-i-C5H11) are also consistent with
its formulation as a nitrosyl thiolate. The mass spectrum shows
a parent ion at m/z 992, and the νNO of the complex is at 1760
cm-1 (KBr).
cm-1 in CH2Cl2 and is tentatively assigned as the νCO of the
intermediate (TTP)Os(CO)(O-i-C5H11) complex (cf 1898 cm-1
for (TTP)Os(CO)). The spectroscopic properties of (TTP)Os-
(NO)(O-i-C5H11) are similar to those of the thiolate analog
A suitable crystal was subjected to a single-crystal X-ray
diffraction analysis, and the molecular structure is shown in
Figure 5. Selected bond lengths and angles are collected in
Table 3. To the best of our knowledge, this is the first reported
X-ray structural determination of an osmium nitrosyl porphy-
rin.33 The axial Os-N(O) and nitrosyl N-O bond lengths are
2.041(7) and 1.086(10) Å, respectively, and the Os-N-O bond
angle of 172.0(9)° indicates linearity of the nitrosyl linkage.
The axial Os-S bond distance is 2.209(3) Å, and the Os-S-C
angle is 111.8(5)°. The osmium atom is displaced 0.03 Å out
of the four-nitrogen porphyrin plane toward the nitrosyl ligand.
The axial S-Os-N(O) group is linear (178.1(2)°), and the
thiolate C(49) atom is essentially eclipsed by the porphyrin N(5)
atom (with a N(5)-Os-S-C(49) torsion angle of 6.5°).
The related reaction of (TTP)Os(CO) with isoamyl nitrite
gives, after workup, the nitrosyl alkoxide (TTP)Os(NO)(O-i-
C5H11) in 57% yield (eq 4). An intermediate for eq 4 is
described in the preceding paragraphs. The νNO is 1770 cm-1
,
higher than that of the thiolate analog (νNO 1760 cm-1) and
higher than that of the related octaethylporphyrin methoxy
complex (OEP)Os(NO)(OMe) (νNO 1745 cm-1 (KBr)).40
Iron Complexes. Unlike the reactions with RuII and OsII
described above, the reaction of the FeII porphyrin (TPP)Fe-
(THF)2 with RSNO (S-nitroso-N-acetyl-L-cysteine methyl ester)
in CH2Cl2 generates the known five-coordinate (TPP)Fe(NO)
complex in 94% isolated yield (eq 5). Although the related
(TPP)Fe(THF)2 + RSNO f (TPP)Fe(NO)
(5)
SR ) NACysMe-S (N-acetyl-L-cysteinate methyl ester)
reaction of the ferric [(TPP)Fe(THF)2]ClO4 derivative with
RSNO did not yield any isolable products, the IR spectrum of
the reaction solution (CH2Cl2) revealed the formation of a
mixture of (TPP)Fe(NO) (νNO 1685 cm-1), free NO (νNO 1845
cm-1), and [(TPP)Fe(NO)(L)]+ (νNO 1919 cm-1; L ) unknown)
(TTP)Os(CO) + i-C5H11ONO f (TTP)Os(NO)(O-i-C5H11)
(4)
(40) (a) Buchler, J. W.; Smith, P. D. Chem. Ber. 1976, 109, 1465. (b)
Antipas, A.; Buchler, J. W.; Gouterman, M.; Smith, P. D. J. Am. Chem.
Soc. 1978, 100, 3015.
observed to form when the reaction is monitored by IR
spectroscopy: a new band appears in the IR spectrum at 1968

3882 Inorganic Chemistry, Vol. 36, No. 18, 1997
Yi et al.
Figure 5. (a) Molecular structure of (TTP)Os(NO)(S-i-C5H11). Hy-
drogen atoms have been omitted for clarity. (b) View along the S(1)-
Os(1) bond showing the orientation of the axial thiolate ligand. The
tolyl substituents on the porphyrin have been omitted.
Figure 6. (a) Molecular structure of the [(TPP)Fe(NO)(i-C5H11OH)]+
cation showing only one of the disordered O-i-C5H11 groups for the
sake of clarity. Hydrogen atoms have been omitted. (b) View along
the axial O(1)-Fe(1) bond showing the orientation of the disordered
alcohol ligand. The phenyl substituents on the porphyrin have been
omitted.
Table 3. Selected Bond Lengths and Angles for
(TTP)Os(NO)(S-i-C5H11)
Bond Lengths (Å)
Os(1)-N(2)
Os(1)-N(1)
Os(1)-N(5)
Os(1)-N(3)
2.035(5)
2.041(7)
2.049(6)
2.074(8)
Os(1)-N(4)
N(1)-O(1)
Os(1)-S(1)
S(1)-C(49)
2.076(9)
1.086(10)
2.209(3)
1.81(2)
Table 4. Selected Bond Lengths and Angles for
[(TPP)Fe(NO)(HO-i-C5H11)]ClO4
Bond Lengths (Å)
Fe(1)-N(1)
Fe(1)-N(2)
Fe(1)-N(3)
Fe(1)-N(4)
1.776(5)
2.014(3)
2.012(3)
2.010(3)
Fe(1)-N(5)
N(1)-O(2)
Fe(1)-O(1)
O(1)-C(45A)
2.016(3)
0.925(6)
2.063(3)
1.450(12)
Bond Angles (deg)
O(1)-N(1)-Os(1)
N(2)-Os(1)-N(1)
N(2)-Os(1)-N(5)
N(1)-Os(1)-N(5)
N(2)-Os(1)-N(3)
N(1)-Os(1)-N(3)
N(5)-Os(1)-N(3)
N(2)-Os(1)-N(4)
N(1)-Os(1)-N(4)
172.0(9)
89.7(2)
90.1(2)
85.5(2)
88.9(3)
92.6(2)
177.9(2)
178.3(2)
88.8(3)
N(5)-Os(1)-N(4)
N(3)-Os(1)-N(4)
N(2)-Os(1)-S(1)
N(1)-Os(1)-S(1)
N(5)-Os(1)-S(1)
N(3)-Os(1)-S(1)
N(4)-Os(1)-S(1)
C(49)-S(1)-Os(1)
C(50)-C(49)-S(1)
90.4(3)
90.6(3)
92.2(2)
178.1(2)
94.3(2)
87.6(2)
89.4(3)
111.8(5)
116.4(13)
Bond Angles (deg)
Fe(1)-N(1)-O(2) 177.1(7) N(4)-Fe(1)-O(1)
N(1)-Fe(1)-O(1) 177.2(2) N(3)-Fe(1)-O(1)
89.41(13)
85.64(13)
88.41(13)
90.89(13)
N(1)-Fe(1)-N(4)
N(1)-Fe(1)-N(3)
N(1)-Fe(1)-N(2)
N(1)-Fe(1)-N(5)
90.6(2) N(2)-Fe(1)-O(1)
91.6(2) N(5)-Fe(1)-O(1)
91.6(2) Fe(1)-O(1)-C(45A) 127.8(6)
91.9(2) Fe(1)-O(1)-C(45B) 131.8(6)
which could not be separated. However, the analogous reaction
with isoamyl nitrite generates the cationic [(TPP)Fe(NO)(HO-
i-C5H11)]+ product in 78% isolated yield (eq 6). Presumably,
adventitious protons (from glass surfaces or solvents) are
involved in the formation of the isolated product.
IR spectrum also reveals bands at 1106-1069 cm-1 due to
uncoordinated perchlorate anion.43 The molecular structure is
shown in Figure 6.
Selected bond lengths and angles are collected in Table 4.
The Fe-N-O linkage is linear (bond angle of 177.1(7)°). The
[(TPP)Fe(THF)2]+ + i-C5H11ONO f
[(TPP)Fe(NO)(HO-i-C5H11)]+ (6)
(41) (a) Scheidt, W. R.; Lee, Y. J.; Hatano, K. J. Am. Chem. Soc. 1984,
106, 3191. (b) Mu, X. H.; Kadish, K. M. Inorg. Chem. 1988, 27, 4720.
(42) This is not unusual for metalloporphyrin complexes. For example, we
do not see the υOH in the spectra of our related [(por)Ru(NO)(H2O)]+
The nitrosyl alcohol product is air-sensitive in the solid state
and more so in solution. The product is also thermally unstable,
readily losing the nitrosyl ligand. The νNO of 1935 cm-1 (KBr)
of the complex is similar to that of the known aqua complex
[(TPP)Fe(NO)(H2O)]ClO4 reported by Scheidt and Hatano (1937
cm-1 (KBr))41a and other cationic iron nitrosyl complexes
reported by Kadish.41b The νOH band was not observed.42 The
20b,38
complexes.
The υOH bands for the related [(TPP)Fe(NO)-
(H2O)]+,41a [(TPP)Fe(H2O)2]+,42a and [(TPP)Fe(EtOH)2]+ 42b were also
not reported: (a) Scheidt, W. R.; Cohen, I. A.; Kastner, M. E.
Biochemistry 1979, 18, 3546. (b) Einstein, F. W. B.; Willis, A. C.
Inorg. Chem. 1978, 17, 3040.
(43) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coor-
dination Compounds, 4th ed.; Wiley-Interscience: New York, 1986;
pp 251-253.

Activation of Thionitrites and Isoamyl Nitrite
Inorganic Chemistry, Vol. 36, No. 18, 1997 3883
Scheme 1
proposed in intermediate complexes of the form [Fe(CN)5-
{N(O)SR}]3- obtained from reactions of nitroprusside with
thiolate anions.10,49 Since Ru forms strong Ru-NO linkages,33
N-coordination of RSNO to the (por)Ru(CO) complex would
•
be expected to result in (por)Ru(CO)(NO) formation and SR
•
release. We could not detect either SR (or the disulfide) or
the as-yet unknown (por)Ru(CO)(NO) complex in either the
bench-scale reactions or the NMR tube reactions.50 In fact, the
results of IR monitoring of the Ru and Os reactions are
consistent with our proposal in Scheme 1. We also propose a
similar reaction pathway for the RONO reactions.51
Fe-N(O) and N-O bond lengths are 1.776(5) and 0.925(6) Å,
respectively. The Fe atom is displaced from the four-nitrogen
porphyrin plane by 0.05 Å toward the NO ligand. The Fe-O
axial bond length is 2.063(3) Å and is longer than the axial
Fe-O bond length in the related aqua cation [(TPP)Fe(NO)-
(H2O)]+ (2.001(5) Å, Fe-N-O ) 174.4(10)°).41a
The solid state structures of the Ru and Os nitrosyl thiolates
represent the first crystal structures of the form (por)M(NO)-
(SR) that are potential models for the NO adducts of cytochrome
P450 and NO synthase. Although a number of Ru thiolate
structures are known,53 only three Ru alkanethiolate structures
were reported prior to our study, and they all involve tertiary
alkyl groups bound to sulfur (Table 5). To the best of our
knowledge, no Ru porphyrin thiolate structures were known
prior to this work. The Ru-S bond length of 2.362 Å in (OEP)-
Ru(NO)(NACysMe-S) is within the 2.195-2.522 Å range for
Ru-S bond lengths of thiolate complexes whose X-ray struc-
tures have been determined (Table 5).64 However, the Ru-
S-C bond angle of 107.1° is smaller than those seen for Ru
alkanethiolates (in the 112-120° range for three complexes).
The Os-S bond length of 2.209(3) Å in (TTP)Os(NO)(S-i-
C5H11) is shorter than that for the only other structurally
characterized Os porphyrin thiolate ((TTP)Os(SC6F4H)2, 2.294-
(3) Å),66 which contains arenethiolate ligands and is also shorter
than the Os alkanethiolate bond length in Os(SCH2Ph)2-
Discussion
As stated in the Introduction, heme plays an important role
in the binding of NO and in the RSNO-induced activation of
GC presumably by direct interaction with the heme iron. The
unusual, yet clean, formal trans addition of RSNO and RONO
to Ru and Os porphyrins thus raises intriguing questions about
metalloporphyrin-catalyzed decompositions of RSNO and RONO.
In the case of the Ru alkyl nitrite reaction, a short-lived
intermediate was observed by IR spectroscopy (Figure 2) and
assigned as the carbonyl alkoxide (por)Ru(CO)(OR). The
higher νCO of 2006 cm-1 relative to that of the parent (por)-
Ru(CO) (νCO ) 1934 cm-1) is consistent with the increased
oxidation state of RuIII in the carbonyl alkoxide relative to RuII
in (por)Ru(CO), resulting in diminished back-bonding to car-
bonyl. Similar intermediates of the form (por)Os(CO)X (X )
thiolate, alkoxide) are also observed in the Os reactions (Figures
4 and 5). The Os six-coordinate carbonyl intermediates also
have higher νCO bands relative to the starting (por)Os(CO),
consistent with the increased oxidation state of OsIII in the
carbonyl alkoxide/thiolate relative to OsII in (por)Os(CO).
Additional support for our OsIII formulation comes from a recent
report by Gross, who isolated authentic (TMP)Os(CO)(Br)
(49) (a) Butler, A. R.; Calsy-Harrison, A. M.; Glidewell, C.; Sørensen, P.
E. Polyhedron 1988, 7, 1197. (b) Butler, A. R.; Calsy-Harrison, A.
M.; Glidewell, C.; Johnson, I. L. Inorg. Chim. Acta 1988, 146, 187.
(50) Disulfides are activated by some transition metal complexes to form
dithiolate derivatives: (a) Kim, J.-H.; Hong, E.; Kim, J.; Do, Y. Inorg.
Chem. 1996, 35, 5112. (b) Reference 56. (c) Reference 64b.
(51) Metal-{N(dO)OR} complexes have been generated by alkoxide
attack on coordinated NO ligands in metal nitrosyls.52
(52) (a) Walsh, J. L.; Bullock, R. M.; Meyer, T. J. Inorg. Chem. 1980, 19,
865. (b) Reed, C. A.; Roper, W. R. J. Chem. Soc., Dalton Trans. 1972,
1243.
(TMP ) tetramesitylporphyrin), which has a νCO of 1933 cm-1
,
higher than that of the parent (por)Os(CO) at 1920 cm-1 44
.
(53) Reviews on metal thiolate complexes: (a) Blower, P. J.; Dilworth, J.
R. Coord. Chem. ReV. 1987, 76, 121. (b) Dilworth, J. R.; Hu, J. AdV.
Inorg. Chem. 1993, 40, 411. (c) Dance, I. G. Polyhedron 1986, 5,
1037. (d) Ashby, M. T. Comments Inorg. Chem. 1990, 10, 297.
(54) Treichel, P. M.; Crane, R. A.; Haller, K. N. J. Organomet. Chem.
1991, 401, 173.
(55) Shaver, A.; El-khateeb, M.; Lebuis, A.-M. Inorg. Chem. 1995, 34,
3841.
(56) Tagge, C. D.; Bergman, R. G. J. Am. Chem. Soc. 1996, 118, 6908.
(57) Mashima, K.; Mikami, A.; Nakamura, A. Chem. Lett. 1992, 1473.
(58) Satsangee, S. P.; Hain, J. H., Jr.; Cooper, P. T.; Koch, S. A. Inorg.
Chem. 1992, 31, 5160.
(59) Burn, M. J.; Fickes, M. G.; Hollander, F. J.; Bergman, R. G.
Organometallics 1995, 14, 137.
(60) Field, L. D.; Hambley, T. W.; Yau, B. C. K. Inorg. Chem. 1994, 33,
2009.
(61) Jessop, P. G.; Rettig, S. J.; Lee, C.-L.; James, B. R. Inorg. Chem.
1991, 30, 4617.
We thus propose that, in the case of Ru and Os porphyrins,
the RSNO incoming group binds to the sixth coordination site
via S-coordination.45 Homolysis of the S-NO bond then
liberates NO, which reacts with the (por)M(CO)(SR) intermedi-
ate to generate the final nitrosyl product (Scheme 1).
Analogous (but anionic) Ru carbonyl thiolate complexes of
the form [(por)Ru(CO)(SR)]- have been generated by thiolate
attack on (por)Ru(CO) or by deprotonation of (por)Ru(CO)-
(RSH).46 Notably, the νCO of [(OEP)Ru(CO)(SR)]- is shifted
25 cm-1 to lower wavenumber relative to (por)Ru(CO).46a
Returning to Scheme 1, however, we note that S-bound RSNO
ligands have been proposed in Hg2+-catalyzed RSNO decom-
positions.47,48 However, N-bound RSNO ligands have been
(44) Gross, Z.; Mahammed, A. Inorg. Chem. 1996, 35, 7260.
(45) The RSNO (and RONO) compounds are stable in solution under
nitrogen at room temperature in the absence of the metalloporphyrin;
hence we do not favor a reaction pathway involving initial attack of
NO from decomposed RSNO. Moreover, such NO attack on (por)M-
(CO) would be expected to generate (por)M(NO)(ONO).37,38
(46) (a) Ogoshi, H.; Sugimoto, H.; Yoshida, Z. Bull. Chem. Soc. Jpn. 1978,
51, 2369. (b) Paulson, D. R.; Hwang, D. S. Inorg. Chim. Acta 1983,
80, L59.
(62) Catala´, R.-M.; Cruz-Garritz, D.; Sosa, P.; Terreros, P.; Torrens, H.;
Hills, A.; Hughes, D. L.; Richards, R. L. J. Organomet. Chem. 1989,
359, 219.
(63) Mura, P.; Olby, B. G.; Robinson, S. D. J. Chem. Soc., Dalton Trans.
1985, 2101.
(64) Other monometallic Ru thiolate structures: (a) Soong, S.-L.; Haln, J.
H., Jr.; Millar, M.; Koch, S. A. Organometallics 1988, 7, 556. (b)
Koch, S. A.; Millar, M. J. Am. Chem. Soc. 1983, 105, 3362. (c) Millar,
M. M.; O’Sullivan, T.; de Vries, N.; Koch, S. A. J. Am. Chem. Soc.
1985, 107, 3714. (d) Dilworth, J. R.; Zheng, Y.; Lu, S.; Wu, Q. Inorg.
Chim. Acta 1992, 194, 99. (e) Bennett, M. A.; Goh, L. Y.; Willis, A.
C. J. Chem. Soc., Chem. Commun. 1992, 1180.
(47) Saville, B. Analyst 1958, 83, 670.
(48) Thionitrites and alkyl nitrites have been employed as NO sources for
metal nitrosyl synthesis: (a) Reference 33, Chapter 2. (b) Bladon, P.;
Dekker, M.; Knox, G. R.; Willison, D.; Jaffari, G. A.; Doedens, R. J.;
Muir, K. W. Organometallics 1993, 12, 1725. (c) Pandey, D. S.;
Agarwala, U. C. Inorg. Chim. Acta 1989, 159, 197. (d) Pandey, D.
S.; Khan, M. I.; Agarwala, U. C. Indian J. Chem. 1987, 26A, 570.
(65) Lynch, W. E.; Lintvedt, R. L.; Shui, X. Q. Inorg. Chem. 1991, 30,
1014.
(66) Collman, J. P.; Bohle, D. S.; Powell, A. K. Inorg. Chem. 1993, 32,
4004.

3884 Inorganic Chemistry, Vol. 36, No. 18, 1997
Yi et al.
ref
Table 5. Representative Structural Data for Monometallic Ru
η1-Thiolatesa,b
Table 7. Structural Data for Fe, Ru, and Os Nitrosyl Porphyrinsa
n in
M-N-O
M-S-C
M-S, Å angle(s), deg ref
{M(NO)}n angle, deg
Iron
[(TPP)Fe(NO)(H2O)]+
[(TPP)Fe(NO)(HO-i-C5H11)]+
[(OEP)Fe(NO)]+
(TPP)Fe(NO)
(TDCPP)Fe(NO)
(OBTPP)Fe(NO)
(TpivPP)Fe(NO)
(TPP)Fe(NO)(1-MeIm)
6
6
6
7
7
7
7
7
174.4(10) 41a
[(η5-C5H5)Ru(PPh2OMe)2(SBut)]PF6
2.274(1) 120.1(1)
54
55
[(η5-C5H5)Ru(NO)(PPh3)(SCMe3)2]BF4 2.386(2) 112.3(3)c
177.1(7)
176.9(3)
149.2(6)
138.8(9)
this work
41a
32
(η5-C5Me5)Ru(NO)(SCMe3)2
(η6-cymene)Ru(SC6H3Me2)
[Ru(SC6HMe4)3(MeCN)2]PF6
2.371(1) 112.07(22)c 56
2.401(1) 118.01(16)c
77
2.311(6) 114.2(8)
2.263(7) 108.9(8)
2.195(8) 111.5(8)
2.198(8) 111.9(8)
2.208(8) 110.7(8)
2.522(3) 116.6(4)
2.472(1) 122.3(1)
2.466(1) 123.8(1)
2.450(2) 113.6(2)
2.470(2) 113.0(2)
2.334(5) 102.9(5)
2.333(4) 102.2(6)
2.419(1) 109.6(2)
57
58
146.4(24) 77
143, 131
142.1(6),
138.3(11)
143.7(6)
78
79
cis-(DMPE)2Ru(Et)(SC6H4Me)
trans-(DMPE)2Ru(SPh)2
59
60
(TPP)Fe(NO)(4-MeIm)
(TPP)Fe(NO)(4-MeIm)‚CHCl3
7
7
80
138.5(11) 80
Ruthenium
cct-Ru(SC6H4Me)2(CO)2(PPh3)2
Ru(SC6F5)2(PPh3)2
61
62
63
[(OEP)Ru(NO)(H2O)]+
(TPP)Ru(NO)(ONO)
(TTP)Ru(NO)(OMe)
(OEP)Ru(NO)(NACysMe-S)
(TTP)Ru(NO)(p-C6H4F)
6
6
6
6
6
171.0(7)
180.0
180.0
20b
38
35
this work
81
174.8(6)
Ru(pyS)(SC5H4N)(CO)2(PPh3)
152.2(5)b
a Abbreviations: DMPE ) 1,2-bis(dimethylphosphino)ethane; cct
) cis,cis,trans.; pyS ) η2-SC5H4N. b References to other monometallic
Ru thiolate structures are given in ref 64. c Obtained from deposited
Supporting Information via the Internet.
Osmium
6
(TTP)Os(NO)(S-i-C5H11)
172.0(9)
this work
a Abbreviations: TDCPP ) tetrakis(o/o′-difluorophenyl)porphyrinato
dianion; OBTPP ) octabromotetraphenylporphyrinato dianion; TpivPP
) tetrakis(o-pivalamidophenyl)porphyrinato dianion. b The bent ge-
ometry may be influenced by crystal packing forces.81
Table 6. Structural Data for Monometallic Os η1-Thiolato
Complexesa
Os-S-C
are known to decompose to form the five-coordinate (por)-
Fe(NO).75
Os-S, Å angle(s), deg ref
Os(SCH2Ph)2[(BA)2en]
2.298(3)
2.315(3)
2.294(3)
2.298(2)
2.343(2)
2.507(1)
2.477(1)
2.424(3)
2.329(1)
2.335(1)
2.196(1)
2.195(1)
2.201(1)
2.414(5)
2.203(6)
2.195(7)
2.220(6)
107.8(4)
102.5(4)
107.8(3)
112.4(2)
112.1(2)
123.9(2)
114.3(2)
109.7(4)
107.6(1)
107.0(1)
114.4(1)
113.4(1)
112.9(1)
117.6(7)
119.6(7)
117.8(8)
111.3(8)
111.2(3)
110.5(3)
113.9(3)
65
Interestingly, the six-coordinate nitrosyl alcohol complex
[(TPP)Fe(NO)(HO-i-C5H11)]+ was isolated from the reaction
of ferric [(TPP)Fe(THF)2]+ with isoamyl nitrite. The linearity
of the Fe-NO link is consistent with its formulation as a
{Fe(NO)}6 complex using the Enemark-Feltham notation.76
Indeed, all three crystal structures reported in this study belong
to the {M(NO)}6 class and contain linear metal-NO linkages
(Table 7). Conversely, {M(NO)}7 compounds would be
expected to contain bent M-N-O groups, as is borne out in
Table 7.
(TTP)Os(SC6F4H)2
trans-Os(salen)(SPh)2
66
67
mer-OsCl(SC6H5)(N2)(PMe2Ph)3
ttt-Os(SC6F5)2(CO)2(PEt2Ph)2
Os(pyS)(SC5H4N)(CO)3
68
69
70
71
Os(SC6F5)2(O2CPh)(PMe2Ph)2
OsCl(SC6F5)3(PMe2Ph)
71
Os(SC6F4H)4(PPh3)3
72
Conclusion
OsCl(SC6F5)2(SC6H4-p-CF3)(PMe2Ph) 2.207(2)
72
Although RSNO and RONO are important in pharmacology
and biochemistry, chemical information on their reactions with
metalloporphyrins was lacking. We have shown for the first
time that RSNO and RONO will react with Fe, Ru, and Os
2.204(2)
2.187(2)
a Abbreviations: ttt ) trans,trans,trans; pyS ) η2-SC5H4N; (BA)2en
) bis(benzoylacetone) ethylenediimine dianion; salen ) N,N′-ethyl-
enebis(salicyclideneaminate).
(73) (a) Hurshman, A. R.; Marletta, M. A. Biochemistry 1995, 34, 5627.
(b) Wang, J.; Rousseau, D. L.; Abu-Soud, H. M.; Stuehr, D. J. Proc.
Natl. Acad. Sci. U.S.A. 1994, 91, 10512.
(74) (a) Hu, S.; Kincaid, J. R. J. Am. Chem. Soc. 1991, 113, 2843. (b)
Delaforge, M.; Servent, D.; Wirsta, P.; Ducrocq, C.; Mansuy, D.;
Lenfant, M. Chem.-Biol. Interact. 1993, 86, 103. (c) Khatsenko, O.
G.; Gross, S. S.; Rifkind, A. B.; Vane, J. R. Proc. Natl. Acad. Sci.
U.S.A. 1993, 90, 11147. (d) Shiro, Y.; Fujii, M.; Iizuka, T.; Adachi,
S.-I.; Tsukamoto, K.; Nakahara, K.; Shoun, H. J. Biol. Chem. 1995,
270, 1617.
(75) O’Keeffe, D. H.; Ebel, R. E.; Peterson, J. A. J. Biol. Chem. 1978,
253, 3509. (b) Ebel, R. E.; O’Keeffe, D. H.; Peterson, J. A. FEBS
Lett. 1975, 55, 198.
(76) Feltham, R. D.; Enemark, J. H. Top. Stereochem. 1981, 12, 155.
(77) Bohle, D. S.; Hung, C.-H. J. Am. Chem. Soc. 1995, 117, 9584.
(78) Nasri, H.; Haller, K. J.; Wang, Y.; Huynh, B. H.; Sheidt, W. R. Inorg.
Chem. 1992, 31, 3459.
[(BA)2en] (2.298(3), 2.315(3) Å).65 The Os-S-C bond angle
(111.8(5)°) of (TTP)Os(NO)(S-i-C5H11) is, however, within the
range found for other Os thiolates whose solid state structures
have been determined by X-ray diffraction (Table 6).
We could not obtain analogous nitrosyl thiolate complexes
with iron porphyrins. NO forms adducts with NO synthase73
and cytochrome P450.74 However, some of these NO adducts
(67) Che, C.-M.; Cheng, W.-K.; Mak, T. C. W. Inorg. Chem. 1986, 25,
703.
(68) Cruz-Garritz, D.; Gelover, S.; Torrens, H.; Leal, J.; Richards, R. L. J.
Chem. Soc., Dalton Trans. 1988, 2393.
(69) Cruz-Garritz, D.; Sosa, P.; Torrens, H.; Hills, A.; Hughes, D. L.;
Richards, R. L. J. Chem. Soc., Dalton Trans. 1989, 419.
(70) Deeming, A. J.; Meah, M. N.; Randle, N. P.; Hardcastle, K. I. J. Chem.
Soc., Dalton Trans. 1989, 2211.
(79) Scheidt, W. R.; Piciulo, P. L. J. Am. Chem. Soc. 1976, 98, 1913.
(80) Scheidt, W. R.; Brinegar, A. C.; Ferro, E. B.; Kirner, J. F. J. Am.
Chem. Soc. 1977, 99, 7315.
(71) Hills, A.; Hughes, D. L.; Richards, R. L.; Arroyo, M.; Cruz-Garritz,
D.; Torrens, H. J. Chem. Soc., Dalton Trans. 1991, 1281.
(72) Arroyo, M.; Chamizo, J. A.; Hughes, D. L.; Richards, R. L.; Roman,
P.; Sosa, P.; Torrens, H. J. Chem. Soc., Dalton Trans. 1994, 1819.
(81) Hodge, S. J.; Wang, L.-S.; Khan, M. A.; Young, V. G., Jr.; Richter-
Addo, G. B. Chem. Commun. 1996, 2283. The unexpected bent Ru-
NO group geometry may be influenced by the interaction of a nearby
tolyl group.

Activation of Thionitrites and Isoamyl Nitrite
Inorganic Chemistry, Vol. 36, No. 18, 1997 3885
porphyrins to produce isolable five-coordinate (Fe only) or six-
coordinate (Fe (RONO only), Ru, Os) nitrosyl derivatives. We
have also reported the first crystal structures of the type (por)M-
(NO)(SR), which are potential structural models for the NO
adducts of cytochrome P450 and NO synthase. A related but
distinct goal that now needs to be addressed is the study of the
kinetics of the reactions of RSNO and RONO with metallopor-
phyrins.
Note Added in Proof. As an addendum to Table 7, the solid
state crystal structure of (TTP)Ru(NO)(NSO) was reported
recently: Bohle, D. S.; Hung, C.-H.; Powell, A. K.; Smith, B.
D.; Wocadlo, S. Inorg. Chem. 1997, 36, 1992.
Supporting Information Available: Additional structural diagrams
and listings of crystal data, non-hydrogen atomic coordinates, aniso-
tropic displacement parameters, bond lengths and angles, hydrogen
coordinates and isotropic displacement parameters, torsion angles, and
least-squares planes (39 pages). Ordering information is given on any
current masthead page.
Acknowledgment. We are grateful to the National Institutes
of Health (FIRST Award 1R29 GM53586-01A1) and the
National Science Foundation (CAREER Award CHE-9625065)
for funding for this research.
IC970282C