Nitric oxide abstracts a nitrogen atom from an osmium nitrido complex to give nitrous oxide

Full text of DOI:10.1021/ja002833v

J. Am. Chem. Soc. 2000, 122, 12391-12392
12391
cm- (the unobserved Q-branch position; Figure 1). The yield of
1
Nitric Oxide Abstracts a Nitrogen Atom from an
Osmium Nitrido Complex To Give Nitrous Oxide
N O was 90 ( 10%, based on a Beer’s law calibration at 2224
2
-
1
2
cm and subtraction of the residual N O present in the NO
7
1
reactant (Figure 1, inset). Kinetic data obtained by H NMR in
CD Cl under 3 atm of NO (pseudo-first-order conditions) are
consistent with first-order decay of 1. Reducing the pressure by
a factor of 3 increases the half-life by roughly the same factor.
Reaction 1 thus appears to be first order in both 1 and NO, with
‡
Michael R. McCarthy, Thomas J. Crevier, Brian Bennett,
2
2
Ahmad Dehestani, and James M. Mayer*
Department of Chemistry, UniVersity of Washington
Box 351700, Seattle, Washington 98195-1700
-
4
-1 -1
at 21 °C.8
rate constant k ≈ 3 × 10
M
s
ReceiVed August 1, 2000
There are two reasonable types of mechanisms for reaction 1.
The nitrosyl complex 2 could be formed by oxygen atom transfer
to the nitrido ligand in 1, analogous to the conversion of 1 to 2
by Me
The chemistry of nitric oxide, NO, is attracting widespread
1,2
interest, from environmental to biological chemistry. As a free
radical, NO reacts rapidly with other odd-electron species, such
9
3
NO (eq 2). In reaction 1, the source of oxygen could be
2 2
as superoxide and alkyl radicals, and reversibly dimerizes to N O .
+
-
NO can be oxidized to NO or to NO
2
(by formal addition of
•-
O ). Reduction of NO to N
ation of N , often in a metal-mediated process. Reported here
2
O commonly occurs via deoxygen-
3
2 2
O
2
is the first example of reduction of NO to N O that occurs by
one-step nitrogen-atom transfer.
Stirring a benzene solution of the osmium nitrido complex
4
TpOs(N)Cl
2
(1) under ∼0.75 atm of NO for 24 h results in
O and the osmium nitrosyl
(2) (eq 1; Tp ) HBpz , hydrotris-
stoichiometric conversion to N
2
from an NO-derived species such as bound or free N
Alternatively, addition of NO to the nitrido ligand would form
the osmium-N O complex, [TpOs(NNO)Cl ] (Scheme 1). Loss
of N O would give [TpOsCl ], which would be converted to 2
by the excess NO present. An N-labeling experiment can
distinguish the two pathways because the first incorporates the
nitrido ligand into the nitrosyl group, while the second converts
2
2
O .
5
complex TpOs(NO)Cl
2
3
2
2
2
2
15
the nitrido ligand into the terminal nitrogen of the N
2
O. The
15
4
14
reaction of TpOs( N)Cl
Scheme 1), as only TpOs( NO)Cl
spectroscopies [<10% Os( NO)]. Gas-phase IR spectra of the
volatiles from the reaction show both the residual
2
with NO supports the second pathway
14
(
2
is formed by IR and mass
15
6
14
N
14NO
(
pyrazolyl)borate). The osmium stoichiometry was determined
1
impurity in the NO (unobserved Q branch at 2224 cm-1) and a
by H NMR and the N
spectrum of N
O at moderate pressures (∼0.10 Torr), using a
low-resolution PE1600 FT-IR, shows broad R and P branches,
2
O was detected by gas-phase IR. The IR
new feature at lower frequency whose R branch overlaps with
2
the P branch of 14N NO (Figure 1, bottom). The Q branch
14
-
1
minimum of the new feature at 2201 cm-1 agrees at this level of
with maxima at 2214 and 2238 cm and a minimum at 2224
-
1
15 14
10
resolution with the 2202.5 cm reported for N NO.
‡
Current address: Symyx Technologies, tcrevier@symyx.com.
Direct, rate-limiting attack of NO on the nitrido ligand of 1 is
consistent with the apparent bimolecular kinetics. Facile dissocia-
(1) (a) Nitric Oxide, Principles and Actions; Lancaster, J., Jr., Ed.; Academic
Press: New York, 1996. (b) Koppenol, W. H. Free Radical Biol. Med. 1998,
5, 385-391. (c) Richter-Addo, G. B.; Legzdins P. Metal Nitrosyls; Oxford
University Press: New York, 1992.
2) See, for instance: (a) Science 1992, 258, 1861, 1862-3 (molecule of
2
tion of N
of the one known N
complex by running the reaction under N
2 2
O from [TpOs(NNO)Cl ] is reasonable given the lability
11,12
2
O complex.
Attempts to observe an N
2
O
(
O (g) gave a more
the year). Stamler, J. S.; Singel, D. J.; Loscalzo, J. Science 1992, 258, 1898-
2
1
3
2
902. (b) McKenney, D. J.; Drury, C. F. Global Change Biol. 1997, 3, 317-
26. (c) Parvulescu, V. I.; Grange, P.; Delmon, B. Catal. Today 1998, 46,
33-316. (d) Burney, S.; Caulfield, J. L.; Niles, J. C.; Wishnok, J. S.;
complex reaction mixture including precipitate(s) which have not
yet been characterized. When the reaction of 1 plus NO is run in
8
0% CD
TpOsCl
CCl solvent appears to cause a small increase in the rate of
disappearance of 1. These results support the intermediacy of
[TpOsCl ] which can be trapped either by NO or by CCl (Scheme
2
Cl
(3),4b with only a 5% yield of 2. The inclusion of some
3
2 4 2 2
/20% CCl instead of CD Cl , the major product is
Tannenbaum, S. R. Mutat. Res. Fund. Mol. Mech. Mutagen. 1999, 424, 37-
4
9.
(
3) For instance, see: (a) Rossi, M.; Sacco, A. J. Chem. Soc., Chem.
4
Commun. 1971, 694. (b) Bhaduri, S.; Johnson, B. F. G.; Savory, C. J.; Segal,
J. A.; Walter, R. H. J. Chem. Soc., Chem. Commun. 1974, 809-810. (c)
Haymore, B. L.; Ibers, J. A. J. Am. Chem. Soc. 1974, 96, 3325. (d) Gwost,
D.; Caulton, K. G. Inorg. Chem. 1974, 13, 414-7. (e) MacNeil, J. H.; Berseth,
P. A.; Bruner, E. L.; Perkins, T. L.; Wadia, Y.; Westwood, G.; Trogler, W.
C. J. Am. Chem. Soc. 1997, 119, 1668-1675. (f) Middleton, A. R.; Wilkinson,
G.; Hursthouse, M. B.; Walker, N. P. J. Chem. Soc., Dalton Trans. 1982,
2
4
-1
(7) (a) The IR extinction coefficient at 2224 cm under our conditions
-4
-1
-1
was 8.3 × 10 Torr cm . (b) Research-grade NO contains small amounts
of N O, which we have not been able to quantitatively remove; for a very
recent approach to N O removal from NO, see: Lorkovi, I. M.; Ford, P. C.
Inorg. Chem. 2000, 39, 632-633, footnote 7.
(8) (a) The concentration of NO in CH Cl
that in CCl [Fogg, P. G. T.; Gerrard, W. Solubility of Gases in Liquids;
2
6
63-5. (g) Schneider, J. L.; Carrier, S. M.; Ruggiero, C. E.; Young, V. G.,
2
Jr.; Tolman, W. B. J. Am. Chem. Soc. 1998, 120, 11408-11418. (h) Bayachou,
M.; Lin, R.; Cho, W.; Farmer, P. J. J. Am. Chem. Soc. 1998, 120, 9888-
2
2
is assumed to be the same as
9
893.
(
4
-2
4) (a) Crevier, T. J.; Mayer, J. M. J. Am. Chem. Soc. 1998, 120, 5595-
Wiley: New York, 1991; p 272], 1.42 × 10 M under 1 atm of pressure. (b)
See also: Shaw, A. W.; Vosper, A. J. J. Chem. Soc., Faraday Trans. 1 1977,
73, 1239-1244.
5
596. (b) Crevier, T. J.; Bennett, B. K.; Bowman, J. A.; Soper, J. D.; Dehestani,
A.; Hrovat, D. A.; Lovell, S.; Kaminski, W.; Mayer, J. M. J. Am. Chem. Soc.
In press.
(
(9) Reference 5, following: Williams, D. S.; Meyer, T. J. J. Am. Chem.
Soc. 1995, 117, 823-4.
5) Crevier, T. J.; Lovell, S.; Mayer, J. M.; Rheingold, A. L.; Guzei, I. A.
J. Am. Chem. Soc. 1998, 120, 6607-6608.
6) In a typical procedure, NO (0.658 atm in a 139 mL bulb, 3.74 mmol)
was condensed at 77 K onto 1 (42.7 mg, 87.3 µmol) and dry degassed benzene
(10) Begun, G. M.; Fletcher, W. H. J. Chem. Phys. 1958, 28, 414-8;
-1
(
ν .
14N15NO ) 2177.6 cm
2 2 3 5
(11) The only known simple complex of N O, [Ru(N O)(NH )
]2+, is quite
(
30 mL). The reaction was stirred for 12 h at ambient temperatures, changing
labile: Armor, J. N.; Taube, H. J. Am. Chem. Soc. 1969, 91, 6874-6.
Diamantis, A. A.; Sparrow, G. J. J. Chem. Soc., Chem. Commun. 1970, 819-
820.
color from orange to brown. The volatiles were transferred to an evacuated
gas-phase IR cell. The reaction solution was evaporated to dryness, and its
1
5
IR and H NMR spectra matched those of independently prepared 2.
2 4
(12) Alternatively, bound N O could be displaced by NO or CCl .
1
0.1021/ja002833v CCC: $19.00 © 2000 American Chemical Society
Published on Web 11/28/2000

12392 J. Am. Chem. Soc., Vol. 122, No. 49, 2000
Communications to the Editor
Scheme 2
molybdenum-tris(amido) complex, in a reaction that appears to
require two molybdenum centers.18 To our knowledge, the
analogous addition of NO to a metal-oxygen multiple bond to
give a nitrite complex is not known, although photolysis of metal
nitrite complexes can give NO19 and the addition of NO to
coordinated dioxygen has been described.20
The relatively facile transfer of N from 1 to NO provides an
upper limit on the OstN bond strength. The reaction 1 + NO a
q
[
2
TpOsCl
2
] + N
2
O has a barrier in the forward direction ∆G )
Figure 1. (a) Gas-phase IR spectra of the residual N
lower trace) and the larger amount of N O in the volatiles after reaction
with TpOs(N)Cl (upper trace). Inset: Beer’s law plot at 2224 cm . (b)
2
O in the NO reactant
-1
2 kcal mol so it is conservative to estimate ∆G° < +20 kcal
(
2
-
1
mol . Since ∆S° ∼ 0 eu for this equilibrium, ∆G° = ∆H°.
-
1
2
-1 21
Adding N to NO to give N
2
O is exothermic by 114.9 kcal mol .
1
5
14
2
Gas-phase IR spectrum of the volatiles from TpOs( N)Cl plus NO.
Coupling these values in a thermochemical cycle gives D(Ost
-
1
N) < 135 kcal mol (Scheme 2).
Scheme 1
The ability of 1 to add NO is consistent with the general
reactivity of this class of osmium(VI) nitrido complexes: reactions
typically involve both reduction of the osmium and bond
formation to the nitrido ligand. For instance, Cp Co induces N-N
2
III
II
-
2 2 2
coupling, forming [TpCl Os (N )Os Cl Tp] , and amines and
carbanions add to the nitrido ligand to form reduced hydrazido
and amido complexes.4 In a number of ways the chemistry of
,22
1
is the reverse of the reactivity of the Cummins molybdenum-
23
tris(amido) system: coupling vs cleavage of N
2
, and formation
vs consumption of N O by nitrogen atom transfer. The reactivity
2
inversion reflects the underlying thermochemistry, that molyb-
denum(III) amides are strongly reducing and the MotN bond is
-
1 24
very strong (155.3 ( 3.3 kcal mol
) while osmium(VI) nitrido
complexes such as 1 are oxidants and have weaker OstN bonds
-
1
(
<135 kcal mol ).
Acknowledgment. We are grateful to the National Science Foundation
for financial support and to Dr. M. Sadil e` k and Dr. M. Lockwood for
assistance.
-
1
). [TpOsCl
2
OTf] , which is an alternative source of [TpOsCl
2
],
also reacts with NO and CCl
4
to give 2 and 3, respectively.13
Nitrogen atom transfer from a metal nitrido to another metal
is well precedented,14 but to our knowledge this is the first
example of N-atom transfer to a nonmetal substrate. The
electrophilic and oxidizing character of 1 seems to be important
JA002833V
(
18) (a) Johnson, A. R.; Davis, W. M.; Cummins, C. C.; Serron, S.; Nolan,
S. P.; Musaev, D. G.; Morokuma, K. J. Am. Chem. Soc. 1998, 120, 2071-
2
085. (b) Laplaza, C. E.; Odom, A. L.; Davis, W. M.; Cummins, C. C.;
to the NO addition reaction. TpOs(N)(OAc)
BPh
in the same manner as 1,15 also appears to form a nitrosyl
complex on treatment with NO. This is based on the reaction
2
, which reacts with
Protasiewicz, J. D. J. Am. Chem. Soc. 1995, 117, 4999-5001; footnote 21
therein describes high-energy processes that remove N from N O, such as
2
3
1
reaction with O( D). (c) Cummins, C. C. Personal communication, April 2000.
(
19) De Leo, M.; Ford, P. C. J. Am. Chem. Soc. 1999, 121, 1980-1981.
-
1
mixture showing an IR band at 1869 cm . However, the less
(20) Collman, J. P.; Kubota, M.; Hosking, J. W. J. Am. Chem. Soc. 1967,
89, 4809-4811.
4
electrophilic TpOs(N)Ph
(
2
is unreactive with NO (as is Mn(N)-
salen) ). In the reverse direction, Cummins et al. have reported
the remarkable removal of a nitrogen atom from N O by a
16
17
(21) NIST chemistry web site http://webbook.nist.gov/chemistry/ accessed
7
/11/00.
2
(22) (a) Demadis, K. D.; El-Samanody, E.-S.; Coia, G. M.; Meyer, T. J. J.
Am. Chem. Soc. 1999, 121, 535-544. (b) Huynh, M. H. V.; El-Samanody,
E.-S.; Demadis, K. D.; Meyer, T. J.; White, P. S. J. Am. Chem. Soc. 1999,
121, 1403-1404.
(23) Cummins, C. C. J. Chem. Soc., Chem. Commun. 1998, 1777-1786.
Peters, J. C.; Cherry, J. P. F.; Thomas, J. C.; Baraldo, L.; Mindiola, D. J.;
Davis, W. M.; Cummins, C. C. J. Am. Chem. Soc. 1999, 121, 10053-10067
and references therein.
(24) (a) Reference 18c. (b) See also for DFT calculations: Neyman, K.
M.; Nasluzov, V. A.; Hahn, J.; Landis, C. R.; R o¨ sch, N. Organometallics
1997, 16, 995-1000. Cui, Q.; Musaev, D. G.; Svensson, M.; Sieber, S.;
Morokuma, K. J. Am. Chem. Soc. 1995, 117, 12366.
(
(
(
(
13) Bennett, B. K.; Lovell, S.; Mayer, J. M. Submitted for publication.
14) Woo, L. K. Chem. ReV. 1993, 93, 1125-1136.
15) Dehestani, A.; Mayer, J. M. Unpublished results.
16) du Bois, J.; Tomooka, C. S.; Hong, J.; Carreira, E. M. Acc. Chem.
Res. 1997, 30, 364-372.
(
17) The related 2,2′:6′,2′′-terpyridine-nitrido complex [(tpy)Os(N)Cl
reacts with 0.53 atm of NO in CH CN overnight but IR spectra of a complex
mixture of products do not indicate the presence of the known nitrosyl complex
(tpy)Os(NO)Cl ]PF : Williams, D. S.; Meyer, T. J.; White, P. S. J. Am. Chem.
Soc. 1995, 117, 823-4.
2 6
]PF
3
[
2
6