Formation and O-atom reactivity of the Os(IV)-sulfilimido and Os(IV)-sulfoximido complexes, cis-/trans-[OsIV(tpy)(Cl)2 (NSC6H3Me2)] and cis-/trans-[OsIV(tpy)(Cl)2 (NS(O)C6</

Full text of DOI:10.1021/ja002874r

9170
J. Am. Chem. Soc. 2001, 123, 9170-9171
Formation and O-Atom Reactivity of the
Os(IV)-Sulfilimido and Os(IV)-Sulfoximido
Complexes, cis-/trans-[OsIV(tpy)(Cl)2(NSC6H3Me2)]
and cis-/trans-[OsIV(tpy)(Cl)2(NS(O)C6H3Me2)]
My Hang V. Huynh,*,‡ Peter S. White,§ and
Thomas J. Meyer*,†
Department of Chemistry
Venable and Kenan Laboratories
The UniVersity of North Carolina at Chapel Hill
Chapel Hill, North Carolina 27599-3290
Chemistry DiVision, MS J514
Figure 1. ORTEP diagram (30% ellipsoids) and labeling scheme for
trans-[OsIV(tpy)(Cl)2(NSC6H3Me2)].
Los Alamos National Laboratory
Rapid reactions occur between cis- or trans-[OsVI(tpy)(Cl)2-
(N)]+ and 3,5-Me2C6H3SH in CH3CN under Ar at room temper-
ature as indicated by color changes from magenta-purple to
reddish brown for the trans isomer and from yellowish brown to
reddish maroon for the cis isomer, eq 1.
Los Alamos, New Mexico 87545
ReceiVed August 3, 2000
The redox reactions of transition metal-containing sulfoxides
and other organosulfur compounds are important both mechanisti-
cally and from biochemical and environmental perspectives.1,2 We
recently reported the existence of S-based, proton-coupled electron
transfer for the couple trans-[OsV(tpy)(Cl)2(NSC6H3Me2)]+/trans-
[OsIV(tpy)(Cl)2(NS(H)C6H3Me2)]+.3 We describe here an exten-
sion of the known reactivity chemistry of the Os(VI)-nitrido
(OsVItN+) complexes, cis-/trans-[OsVI(tpy)(Cl)2(N)]+, toward
bases to give the corresponding sulfilimido complexes. The
products, cis-/trans-[OsIV(tpy)(Cl)2(NSC6H3Me2)], which are rela-
tively rare examples of sulfilimide coordination, undergo O2 or
air oxidation to give the sulfoximido complexes, cis-/trans-[OsIV-
(tpy)(Cl)2(NS(O)C6H3Me2)], for which there is also little literature
precedence. Remarkably, given the continuing interest in metal-
catalyzed oxygen atom transfer in chemistry and biology, the
sulfoximido complexes undergo facile, ligand-based O-atom
transfer.4,5
[OsVI(tpy)(Cl)2(N)]+ + 3,5-Me2C6H3SH f
[(tpy)(Cl)2OsIVdN-SC6H3Me2] + H+ (1)
Evaporation of the reaction mixtures to a small volume under
vacuum precipitates [1] which are protonated to [2]PF6, [OsIV-
(tpy)(Cl)2(NS(H)C6H3Me2)]PF6 ([2A]PF6 ) trans and [2B]PF6
) cis), and precipitated by adding HPF6 to a solution mixture of
2:1 (v/v) CH3CN:H2O. Both isomers of [1] and [2]PF6 have been
isolated and characterized by cyclic voltammetry (Supporting
Information Figure 1), X-ray crystallography, elemental analysis,
and infrared, 1H NMR, and UV-visible (Supporting Information
Figure 2) spectroscopies.
The X-ray crystal structure of trans-[OsIV(tpy)(Cl)2(NSC6H3-
Me2)] ([1A]) with crystals grown by slow diffusion of Et2O into
a DMF solution is shown in Figure 1. In the structure, the distorted
octahedral arrangement of ligands at Os in the parent nitrido
complex is retained in the sulfilimido product. The Os-N(tpy)
bond lengths range from 2.012(3) to 2.065(3) Å with the shortest
Os-N(tpy) bond trans to the sulfilimido ligand. The Os-
N(sulfilimido) and N(1)-S(1) bond lengths are rather short at
1.890(3) and 1.596(4) Å, respectively, consistent with multiple
bonding.6 Angle N(1)-S(1)-C(1) ) 104.28(18)° is consistent
with pseudo-sp3-hybridization at the S-atom of the sulfilimido
ligand. The short Os-N(sulfilimido) bond length, bent angle
Os(1)-N(1)-S(1) ) 129.52(21)°, and diamagnetism of the com-
plexes7 are all consistent with d4 spin-paired Os(IV) complexes.
There are structural similarities with related Os(IV)-phosphor-
animinato (trans-[OsIV(tpy)(Cl)2(NPPh3)]+)8 and hydrazido com-
plexes ([OsIV(tpy)(bpy)(NN(CH2)4O)]2+,9 cis-[OsIV(tpy)(NCCH3)-
(Cl)(NN(CH2)4O)]+,10 and cis-[OsIV(tpy)(NCCH3)2(NN(CH2)4-
O)]2+).11
† Present address: Associate Laboratory Director for Strategic and Sup-
porting Research, Los Alamos National Laboratory, MS A127, Los Alamos,
NM 87545. E-mail: tjmeyer@lanl.gov. Telephone: 1-505-667-8597. Fax:
1-505-667-5450.
‡ Present address: Director-Funded Postdoctoral Fellow, Los Alamos
National Laboratory, Chemistry Division MS J514, Los Alamos, NM 87545.
E-mail: huynh@lanl.gov. Telephone: 1-505-667-3968. Fax: 1-505-667-3314.
§ Present address: Department of Chemistry, The University of North
Carolina at Chapel Hill, Chapel Hill, NC 27599-3290.
(1) (a) Espenson, J. H.; Abu-Omar, M. M. ACS AdV. Chem. 1997, 253,
3507. (b) Adam, W.; Richter, M. J. Acc. Chem. Res. 1994, 27, 57. (c) Collman,
J. P.; Zhang, X.; Lee, V. J.; Uffelman, E. S.; Brauman, J. I. Science 1993,
261, 1404. (d) Holm, R. H. Chem. ReV. 1987, 87, 1401. (e) Sheldon, R. A.;
Kochi, J. K. Metal-Catalyzed Oxidations of Organic Compounds; Academic
Press: New York, 1981.
(2) For selected examples, see: (a) Peters, J. W.; Lanzilotta, W. N.; Lemon,
B. J.; Seefeldt, L. C.; Lance, C. Science 1998, 282(5395), 1853. (b) Jin, X.;
Kazuhito, I.; Carl, B. E. Proc. Natl. Acad. Sci. U.S.A. 1998, 95(25), 14851.
(c) Gyula, K.; Peter, C.; Corinna, P.; Roland, L. J. Eur. Mol. Biol. Organ.
1999, 18(14), 3981. (d) Elisabeth, D.; Maria, V.-V.; Tomoko, O.; Fevzi, D.
J. Bioenerg. Biomembr. 1999, 31(3), 275. (e) William, L. N.; Jason, C.; Dennis,
D. R.; Lance, S. C. Biochemistry 1998, 37(32), 11376. (f) Zhaolei, Z.; Lishar,
H.; Vladimir, S. M.; Young-In, C.; Kyu, K. K.; Li-Wei, H.; Antony, C. R.;
Edward, B. A.; Sung-Hou, K. Nature (London), 1998, 392(6677), 677. (g)
Birgit, S.; Roswitha, W.; Martin, E. Biochemistry 1997, 36(15), 4471.
(3) Huynh, M. H. V.; White, P. S.; Meyer, T. J. Angew. Chem., Int. Ed.
2000, 39(22), 4101.
(4) (a) Oae, S. Organic Sulfur Chemistry: Structure and Mechanism; Oae,
S.; Ed.; CRC Press: Boca Raton, FL, 1991, 1. (b) Trujillo, H. A.; Casado, C.
M.; Ruiz, J.; Astruc, D. J. Am. Chem. Soc. 1999, 121, 5674. (c) Wang, D.
M.; Angelici, R. J. J. Am. Chem. Soc. 1996, 118, 935. (d) Kaukorat, T.; Neda,
I.; Schmutzler, R. Coord. Chem. ReV. 1994, 137, 53.
(5) For selected examples, see: (a) Donahue, J. P.; Goldsmith, C. R.;
Nadiminti, U.; Holm, R. H. J. Am. Chem. Soc. 1998, 120, 12869. (b) Paul, F.
Coord. Chem. ReV. 2000, 203, 269. (c) deBruin, B.; Boerakker, M. J.;
Verhagen, J. A. W.; deGelder, R.; Smits, J. M. M.; Gal, A. W. J. Chem.s
Eur. J. 2000, 6, 298. (d) Owens, G. S.; Aries, J.; AbuOmar, M. M. Catal.
Today 2000, 55, 317. (e) Campora, J.; Palma, P.; Carmona, E. Coord. Chem.
ReV. 1999, 195, 207. (f) Arzoumanian, H. Coord. Chem. ReV. 1998, 180, 191.
(g) Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37(15), 2047. (h) Parkin, G.
Progr. Inorg. Chem. 1998, 47, 1.
(6) Selected bond lengths and angles in the S-protonated Os(IV)-
sulfilimido complex are listed for comparison: Os-N(tpy) ) 2.015(10),
2.108(9), and 2.129(9) Å (with the shortest Os-N(tpy) bond trans to the
sulfilimido ligand); Os-N(sulfilimido) ) 1.906(10) Å (double bond); N(1)-
S(1) ) 1.706(9) Å (single bond); Os(1)-N(1)-S(1) ) 130.4(6)°; and
N(1)-S(1)-C(1) ) 101.6(5)°.
(7) Cyclic voltammetry; elemental analysis; X-ray crystal structure; and
1
infrared, UV-visible, and H NMR spectroscopies for [1], [2]PF6, [3], and
[4]Cl are provided in the Supporting Information. From the absence of
paramagnetic broadening in the 1H NMR spectra, these are diamagnetic d4
complexes.
(8) Demadis, K. D.; Bakir, M.; Klesczewski, B. G.; Williams, D. S.; White,
P. S.; Meyer, T. J. Inorg. Chim. Acta 1998, 270, 511.
(9) Coia, G. M.; Devenney, M.; White, P. S.; Meyer, T. J.; Wink, D. A.
Inorg. Chem. 1997, 36, 2341.
(10) Huynh, M. H. V.; El-Samanody, E.-S.; Demadis, K. D.; White, P. S.;
Meyer, T. J. Inorg. Chem. 2000, 39, 3075.
10.1021/ja002874r CCC: $20.00 © 2001 American Chemical Society
Published on Web 08/25/2001

Communications to the Editor
J. Am. Chem. Soc., Vol. 123, No. 37, 2001 9171
The kinetics of formation of [1] were studied in CH3CN at
25.0 ( 0.1 °C by UV-visible monitoring at λmax ) 468 nm for
[1A] and at λmax ) 472 nm for [1B]. Under pseudo-first-order
conditions in 3,5-dimethylbenzenethiol, the kinetics were first-
order in both [OsVItN+] and [3,5-Me2C6H3SH] (Supporting Infor-
mation Figure 3) with k[1A] ) (3.60 ( 0.08) × 10-2 M-1 s-1 and
k[1B] ) (3.21 ( 0.06) M-1 s-1. This compares with ktpy ) (24.6
( 0.6) M-1 s-1 for the reaction between trans-[OsVI(tpy)(Cl)2-
(N)]+ and triphenylphosphine sulfide12 under the same conditions.
There is only a limited literature precedence for complexes
containing the sulfilimido ligand13-15 and no information about
the reactivities of the complexes or ligands. We find a reversible
electron-transfer chemistry for the Os complexes. In 0.1 M TBAH
(TBAH ) tetrabutylammonium hexafluorophosphate) in CH3CN
with added HPF6, chemically reversible waves for the [OsV/IV(tpy)-
(Cl)2(NS(H)C6H3Me2)]2+/+ and [OsIV/III(tpy)(Cl)2(NS(H)C6H3Me2)]+/0
couples for [2A]PF6 appear at E1/2 ) +1.17 V and E1/2 ) -0.08
ν(SdO) stretches appearing at 1250 cm-1 for [3A] and at 1275
cm-1 for [3B].7 From the absence of paramagnetic broadening in
1
the H NMR spectra, these are also diamagnetic d4 complexes.
The O-atom-transfer chemistry is reversible. Rapid reactions
occur between [3] and stoichiometric PPh3 in CH3CN under Ar
to give back [1] and OPPh3, the latter as shown by IR (νPdO
)
1193 (vs)) and 31P NMR, eq 5, and between [3] and trans-stilbene
to give the epoxide as shown by GC-MS, eq 6.
[(tpy)(Cl)2OsIVdN-S(O)C6H3Me2] + PPh3 f
[(tpy)(Cl)2OsIVdN-SC6H3Me2] + OPPh3 (5)
[(tpy)(Cl)2OsIVdNS(O)C6H3Me2] + trans-PhCHdCHPh f
[(tpy)(Cl)2OsIVdNSC6H3Me2] + trans-PhCH(O)CHPh (6)
V (Supporting Information Figure 1C) and for [2B]PF6 at E1/2
)
We are currently investigating the O-atom-transfer reactivity of
[3] toward other reactants and the possibility of developing
catalytic, oxygen-based oxidation cycles.
+1.21 V and E1/2 ) -0.09 V, versus SSCE. These potentials are
reminiscent of potentials for the Os(V/IV) and Os(IV/III) couples
for the Os(IV)-phosphoraniminato complexes, [OsIV(tpy)(Cl)2-
(NPR3)]+. For example, in 0.1 M TBAH in CH3CN, E1/2 ) 0.92
V and -0.27 V (V vs SSCE) for the trans isomer8 of [OsIV(tpy)-
(Cl)2(NPPh3)]+ and 1.06 V and -0.16 V for the cis isomer.12
On the basis of pH-dependent electrochemical measurements,
the Os(V/IV) couple of [2A]PF6 is pH-dependent in 1:1 (v/v)
CH3CN:H2O (µ ) 1.0 M KNO3) from pH ) 0.0 to 1.3 (59 mV/
pH) and pH-independent above pH ) 1.3. On the basis of the
pH-dependence data, pKa ) 1.31 ( 0.03 for the acid-base equi-
librium in eq 2, (Supporting Information Figure 4). The pKa for
the analogous Os(IV)-hydrazido complex, trans-[OsIV(tpy)(Cl)2-
(N(H)N(CH2)4O)]+, is 3.20 ( 0.04 under comparable conditions.16
There is also an irreversible O-atom-transfer chemistry in
DMSO. When cis- or trans-[OsIV(tpy)(Cl)2(NS(H)C6H3Me2)]+ are
dissolved in DMSO, a color change occurs from brownish red to
bright red concurrent with formation of the sulfoximido com-
plexes, [OsIV(tpy)(Cl)2(NS(O)Me2)]+ ([4A]+ ) trans and [4B]+
) cis). This reaction may occur by O-atom transfer from DMSO
to the sulfilimido ligand, but the mechanism is unclear. The
cations [4]+ were isolated as their Cl- salts, and crystals of [4A]-
Cl were grown in neat DMSO. The structure of [4A]Cl was
determined by X-ray crystallography.17
There is also little literature precedence for the coordination
of sulfoximido ligands, NS(O)R2 .
2- 18,19 In the structure of [4A]+,
the average angle of 109.035(18)° at the S-atom is consistent with
sp3-hybridization. The short bond lengths of S(1)-N(1) )
1.560(3) and S(1)-O(1) ) 1.443(3) Å relative to those of S(1)-
C(2) ) 1.749(4) and S(1)-C(3) ) 1.756(4) Å confirm S-N(sul-
foximido) and S-O(sulfoximido) double bonds. The longer bond
length of Os(1)-N(1) ) 2.119(3) Å in [4A]Cl compared to those
of [1A] (1.890(3) Å), [1A]+ (1.906(10) Å), and cis-[OsIV(tpy)-
(Cl)(NCCH3)(NSC6H3Me2)]+ (1.895(6) Å)20 are consistent with
an Os-N(sulfoximido) single bond.
These results are important in demonstrating new routes for
the preparation of complexes containing the sulfilimido and
sulfoximido ligands, the existence of a multiple-electron-transfer
chemistry for the Os-sulfilimido complexes based on the metal,
and the existence of a reversible O-atom-transfer reactivity based
on the ligand. There are analogies in the latter in the redox
chemistry of metal-oxo complexes.
trans-[OsIV(tpy)(Cl)2(NS(H)C6H3Me2)]+ h
trans-[OsIV(tpy)(Cl)2(NSC6H3Me2)] + H+ (2)
Remarkably, in addition to the reversible electron-transfer
chemistry, there is a reversible atom-transfer chemistry based on
the sulfilimido ligand. Rapid reactions occur between [2]PF6 and
OrNMe3 in CH3CN to give the corresponding Os(IV)-sulfox-
imido complexes, [OsIV(tpy)(Cl)2(NS(O)C6H3Me2)] ([3A] ) trans
and [3B] ) cis), eq 3.
Acknowledgments are made to the National Science Foundation under
Grant CHE-9503738, the Los Alamos National Laboratory (DOE) under
Grant 10730-001-00-2C, the Laboratory Directed Research and Develop-
ment Program for support of this research. M.H.V.H. gratefully acknowl-
edges postdoctoral fellowship support from the Director’s Office of Los
Alamos National Laboratory. Los Alamos National Laboratory is operated
by the University of California for the U.S. Department of Energy under
Contract W-7405-ENG-36.
The same products form rapidly when the deprotonated forms
[1] are exposed to O2, eq 4.
Both isomers of [3] were characterized by cyclic voltammetry,
elemental analysis, UV-visible (Supporting Information Figure
1
Supporting Information Available: Text containing characterizations
and Figure captions, Tables containing crystal data, atomic coordinates,
isotropic thermal parameters, bond distances, angles, packing diagrams,
and Figures 1-5 (PDF). This material is available free of charge via the
Internet at http://pubs.acs.org.
5A,B), H NMR, and infrared spectroscopies with characteristic
(11) Huynh, M. H. V.; Lee, D. G.; White, P. S.; Meyer, T. J. Inorg. Chem.
2001, 40, 3842-3849.
(12) Huynh, M. H. V.; White, P. S.; Meyer, T. J. Inorg. Chem. 2000, 39,
2825.
(13) (a) Roesky, H. W.; Zimmer, M.; Noltemeyer, M.; Schmidt, H. G.
Chem. Ber. 1988, 121, 1377. (b) Roesky, H. W.; Zimmer, M.; Schmidt, H.
G.; Noltemeyer, M. Z. Naturforsch. 1988, 43b, 1490 and references therein.
(14) Williams, C. V.; Mu¨ller, M.; Leech, M. A.; Denning, R. G.; Green,
M. L. H. Inorg. Chem. 2000, 39, 2538.
JA002874R
(17) Huynh, M. H. V.; White, P. S.; John, K. D.; Meyer T. J. Angew. Chem.,
Int. Ed. 2001. Accepted for publication.
(15) Cramer, R. E.; Ariyaratne, K. A. N. S.; Gilje, J. W. Z. Anorg. Alg.
Chem. 1995, 621, 1856.
(18) Roesky, H. W.; Scholz, M.; Edelmann, F.; Noltemeyer, M. Chem.
Ber. 1987, 120, 1881.
(16) Huynh, M. H. V.; El-Samanody, E.-S.; Demadis, K. D.; White, P. S.;
Meyer, T. J. J. Am. Chem. Soc. 1999, 121, 1403.
(19) Schmidbaur, H.; Kammer, G. Chem. Ber. 1969, 102, 4135.
(20) Huynh, M. H. V.; John, K. D.; Meyer T. J. Manuscript in preparation.