Synthesis and X-ray Structure of an H2S Complex, RuCl2(P-N)(P(p-tolyl)3)(SH2) (P-N = 0-(Diphenylphosphino)-N,N-dimethylaniline)

Full text of DOI:10.1021/ic9707772

5426
Inorg. Chem. 1997, 36, 5426-5427
Synthesis and X-ray Structure of an H2S Complex, RuCl2(P-N)(P(p-tolyl)3)(SH2)
(P-N ) o-(Diphenylphosphino)-N,N-dimethylaniline)
D. Chandrika Mudalige, Erin S. Ma, Steven J. Rettig, Brian R. James,* and William R. Cullen
Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1 Canada
ReceiVed June 26, 1997
The interaction of transition metal complexes with H2S
continues to attract attention. Such chemistry is of relevance
in the biological sulfur cycle, in the formation of ores, in
hydrodesulfurization catalysis, and in the use of H2S as a source
of H2 and elemental sulfur (or organosulfur compounds).
Literature dealing with these topics is plentiful and can be traced
through recent references.1,2 However, isolation and charac-
terization of metal complexes containing H2S remain challeng-
ing,2,3 as such species tend to undergo oxidative addition
reactions to give products with SH ligands or bridged or terminal
sulfide,4 and only recently has an H2S complex been character-
ized crystallographically.2 This was the structure reported by
Sellmann et al. of the Ru(II)-complex Ru(SH2)(PPh3)(‘S4’)‚THF
(‘S4’ ) 1,2-bis[(2-mercaptophenyl)thio]ethane(2-)) formed by
the reaction of the polymeric complex [Ru(PPh3)(‘S4’)]x with
liquid H2S at -70 °C; the reaction with H2S gas at room
temperature in THF resulted in a mixture of the bridging sulfide
complex [(µ-S2){Ru(PPh3)(‘S4’)}2] and other uncharacterized
products depicting the more typical reactivity of H2S with
transition metal complexes.2
N2 and were deoxygenated by freeze-thaw-pump cycles prior
to use; CDCl3 (Merck Frosst Canada) was dried over activated
molecular sieves (Fisher 4A) and stored under Ar. Purified H2S
(Matheson) was used as supplied. The precursors, 5-coordinate
complexes 1a,b, were made as described previously.5 Solution
NMR spectra were recorded on a Varian XL300 spectrometer
(121.4 Mhz for 31P{1H}) using TMS or PPh3 (δP -5.59 in
CDCl3 vs 85% H3PO4) as external references, with positive
shifts implying lower fields; δP shifts are reported relative to
the H3PO4. IR spectra (Nujol mulls between KBr plates) were
recorded on a Bomem MB-102 FT spectrometer.
Note that H2S is extremely toxic and all experimentation
inVolVing this reagent should be carried out in a well-Ventilated
fume hood!
For the preparations of RuCl2(o-Ph2PC6H4NMe2)(PR3)(SH2)
(R ) Ph, 2a; R ) p-tolyl, 2b), H2S gas (2 mL) was injected
into a solution of RuCl2(P-N)(PR3) (1a or 1b, 0.06 mmol) in
C6H6 (1 mL). Hexanes (10 mL) were added to the resultant
red solution under Ar, and the mixture was stirred for 15 min.
The yellow product (2a or 2b) was filtered off and dried under
vacuum overnight (95% yield). Complex 2b was also prepared
in 100% yield by reacting 0.03 mmol of powdered, solid 1b
with H2S gas (1 atm) at ∼20 °C; the initally green solid turned
yellow within 1 min, and the mixture was “stirred” for a further
2 h. Acceptable elemental analysis was obtained only for 2b.
Anal. Calcd for C41H43Cl2NP2SRu: C, 60.37; H, 5.31; N, 1.72;
S, 3.93. Found: C, 60.62; H, 5.33; N, 1.67; S, 4.25. 31P{1H}
NMR (CDCl3, 20 °C, under 1 atm H2S) [δA, δX (2J Hz)]: 2a,
48.91, 42.82 (30.1); 2b, 50.31, 40.91 (30.3). 1H NMR (CDCl3,
293 K, under 1 atm H2S). 2a, δ 1.05 (br, 2H, Ru-SH2), 2.97
(s, 3H, N-Me), 3.66 (s, 3H, N-Me), 6.50-8.40 (m, 26H,
aromatic); 2b, δ 0.95 (br, 2H, Ru-SH2), 2.15 (s, 9H, Me of
p-tolyl), 3.05 (s, 3H, N-Me), 3.41 (s, 3H, N-Me), 6.35-8.10
(m, 26H, aromatic). Each spectrum also shows a singlet at δ
0.75 due to free H2S. Red-brown crystals of 2b were grown
by layering a THF solution of the complex with hexanes.
Crystallographic data for RuCl2(o-Ph2PC6H4NMe2)[P(p-
tolyl)3](SH2) (2b) are given in Table 1. Measurements were
collected on a Rigaku AFC6S diffractometer at 294 K. The
final unit-cell parameters were obtained by least-squares analysis
on the setting angles for 21 reflections with 2θ ) 10.60-17.20.
The intensities of 3 representative reflections, measured every
200 reflections throughout the data collection, decayed uniformly
by 23.7%, and a polynomial correction factor was applied. The
structure was solved by conventional heavy atom methods, the
coordinates of the Ru atom being determined by the Patterson
function and those of the remaining non-hydrogen atoms from
a subsequent Fourier synthesis. The asymmetric unit contains
a partially occupied water site on a 2-fold axis and a THF
solvent site disordered about a 2-fold axis. Only one of the
H2S protons could be located. Solvent hydrogens were not
included in the model. Calculations were performed using a
TEXSAN/TEXRAY structure analysis package (Molecular
We report here the synthesis, isolation, and spectroscopic and
X-ray structural characterization of a Ru(II)-H2S complex,
RuCl2(P-N)(PR3)(SH2), 2b, where P-N is o-(diphenylphos-
phino)-N,N-dimethylaniline and R ) p-tolyl (eq 1); spectro-
H2S
yArz
RuCl2(P-N)(PR3)
RuCl2(P-N)(PR3)(SH2)
(1)
1a, R ) Ph
2a, R ) Ph
1b, R ) p-tolyl
2b, R ) p-tolyl
scopic evidence for complex 2a is also presented. To our
knowledge, this is the first example of a structurally character-
ized transition metal-H2S complex formed under ambient
conditions.
Experimental procedures were carried out under N2 or Ar
using standard Schlenk techniques. Reagent grade C6H6,
hexanes, and THF were distilled from Na/benzoquinone under
(1) (a) Wong, T. Y. H.; Barnabas, A. F.; Sallin, D.; James, B. R. Inorg.
Chem. 1995, 34, 2278. (b) McDonald, R.; Cowie, M. Inorg. Chem.
1993, 32, 1671. (c) Jessop, P. G.; Lee, C.-L.; Rastar, G.; James, B.
R.; Lock, C. J. L.; Faggiani, R. Inorg. Chem. 1992, 31, 4601. (d) Shih,
K.-Y.; Fanwick, P. E.; Walton, R. A. Inorg. Chem. 1992, 31, 3663.
(2) (a) Sellmann, D.; Lechner, P.; Knoch, F.; Moll, M. Angew. Chem.,
Int. Ed. Engl. 1991, 30, 552. (b) Sellmann, D.; Lechner, P.; Knoch,
F.; Moll, M. J. Am. Chem. Soc. 1992, 114, 922.
(3) (a) Cecconi, F.; Innocenti, P.; Midollini, S.; Moneti, S.; Vacca, A.;
Ramirez, J. A. J. Chem. Soc., Dalton Trans. 1991, 1129. (b) Besenyei,
G.; Lee, C.-L.; Xie, Y.; James, B. R. Inorg. Chem. 1991, 30, 2446.
(c) Rabinovich, D.; Parkin, G. J. Am. Chem. Soc. 1991, 113, 5904.
(d) Antonelli, D. M.; Cowie, M. Inorg. Chem. 1990, 29, 3339. (e)
Klein, D. P.; Kloster, G. M.; Bergman, R. G. J. Am. Chem. Soc. 1990,
112, 2022.
(4) (a) Amarasekera, J.; Rauchfuss, T. B. Inorg. Chem. 1989, 28, 3875.
(b) Raab, K.; Beck, W. Chem. Ber. 1985, 118, 3830. (c) Urban, G.;
Sunkel, K.; Beck, W. J. Organomet. Chem. 1985, 290, 329. (d)
Crabtree, R. H.; Davis, M. W.; Mellea, M. F.; Mihelcic, J. M. Inorg.
Chim. Acta 1983, 72, 223. (e) Harris, P. J.; Knox, S. A. R.; Mckinney,
R. J.; Stone, F. G. A. J. Chem. Soc., Dalton Trans. 1978, 1009. (f)
Herberhold, M.; Suss, G. Angew. Chem., Int. Ed. Engl. 1976, 15, 366.
(g) Kuehn, C. G.; Taube, H. J. Am. Chem. Soc. 1976, 98, 689. (h)
Morelli, D.; Segre, A.; Ugo, R.; LaMonica, G.; Cenini, S.; Conti, F.;
Bonati, F. Chem. Comm. 1967, 524.
(5) Mudalige, D. C.; Rettig, S. J.; James, B. R.; Cullen, W. R. J. Chem.
Soc., Chem. Commun. 1993, 830.
S0020-1669(97)00777-5 CCC: $14.00 © 1997 American Chemical Society

Communications
Inorganic Chemistry, Vol. 36, No. 24, 1997 5427
Table 1. Crystallographic Data
Ru(III)-mercapto complex, but the structural parameters,
observed diamagnetism, reversible solution behavior, and
spectroscopic evidence for coordinated H2S ligand show the
complex to be the Ru(II)-H2S adduct. The Ru-S bond length
of 2.330(4) Å is comparable to that of Sellmann’s complex
(2.399(5) Å)2 and is significantly shorter than that of terminal
mercapto complexes (average Ru-SH, 2.46 Å).1c,6 The length
of the located S-H bond (1.25 Å) is shorter than that found in
gaseous H2S (1.33 Å)7 and is in the range reported for
Sellmann’s complex (average 1.20 Å).2 The Ru-Cl(1)(trans to
phosphorus) (2.469 Å) and Ru-Cl(2)(trans to sulfur) (2.429
Å) distances are typical of those of related Ru(II) complexes6,8
and are longer than those in the corresponding Ru(III) species,
mer-RuCl3(P-N)(PPh3): 2.40 Å (trans to phosphorus) and 2.33
Å (for mutually trans chlorines).9 The stability of the crystals
of 2b is unparalleled; the crystal stability of Sellman’s H2S
complex results from intermolecular H-bonds between the H2S
ligand and both a S-atom of the macrocyclic ligand and a THF
solvate, the solvent-free complex being labile and not charac-
terizable crystallographically.2 In 2b, there are no such stabiliz-
ing interactions with the coordinated H2S.
compd
RuCl2(o-Ph2PC6H4NMe2)[P(p-MeC6H4)3]-
(SH2)‚0.5THF‚0.41H2O
formula
fw
cryst system
space group
a, Å
C43H47.82O0.91Cl2NP2RuS
859.22
tetragonal
I41/a (No. 88)
20.587(7)
38.51(1)
16322(9)
16
c, Å
V, Å3
Z
F
T, °C
calc, g/cm3
1.398
21
radiation
µ, cm-1
R(F)
Mo
6.8
0.048
0.057
Rw(F)
2
a R ) ∑||Fo| - |Fc||/∑|Fo|, Rw ) [∑w(|Fo| - |Fc|)2/∑w(Fo )]1/2
.
The 1H NMR data reveal the coordinated H2S and strong νSH
IR bands at 2506 and 2476 cm-1 (2a) and 2495 and 2449 cm-1
(2b) compare with those of 2410 and 2290 cm-1 of Sellman’s
complex which are lower because of the presence of the
S-H‚‚‚S and S-H‚‚‚O hydrogen bridges. Unlike previously
reported H2S complexes, 2a,b are fairly stable as solids under
Ar and do not lose H2S under vacuum over 24 h at ambient
temperature, but they rapidly decompose to uncharacterized
black solids when exposed to air.
In C6D6 solution under Ar, 2a,b reversibly lose H2S, and
integrations of the NMR data yield, for example, a value of ∼
30 M-1 at 20 °C for the associative equilibrium constant for
the reaction 1b + H2S ) 2b.
Species 1 are highly reactive generally toward small mol-
ecules; we have reported on the η2-H2 and η1-N2 derivatives5
and will report elsewhere on the binding of O2, CO, H2O, SO2,
CH3OH, and C2H5SH.9
Figure 1. ORTEP plot of 2b (H atoms omitted for clarity). Thermal
ellipsoids for non-hydrogen atoms are drawn at 33% probability.
Structure Corp., 1985). The final R and Rw values were 0.048
and 0.057, respectively, for 2365 reflections with I g 2.0σ(I).
Selected bond lengths and bond angles appear in Table 2
(Supporting Information). Complete tables of crystallographic
data, atomic coordinates, anisotropic thermal parameters, bond
lengths and angles, torsion angles, intermolecular contacts, and
least-square planes are included as Supporting Information.
Interaction of the 5-coordinate species RuCl2(P-N)(PR3) (1)5
with 1 atm of H2S in benzene, CHCl3, or THF solution at 20
°C leads to rapid and quantitative formation of the H2S species
2; the reactions are reversible in solution if H2S is removed by
vacuum or by purging the system with Ar (see below). The
complexes (2) were isolated as air-sensitive, yellow powders
by the addition of hexanes and drying under vacuum (95%
yield); 2b was also formed quantitatively by reacting solid 1b
with 1 atm of H2S at 20 °C, although surprisingly 1a did not
react with H2S under corresponding conditions.
X-ray analysis of 2b reveals a close to octahedral geometry
around the Ru with cis-chlorides and the H2S trans to a chloride
(Figure 1). The trans bond angles are in the range 170.0-
174.6°, and the cis angles range from 81.3 to 94.3°. The chelate
bite angle P(1)-Ru-N(1) of 81.3° is similar to that found in
1b (81.81°).5 Only one H atom of the coordinated H2S was
located in the structure which thus erroneously portrays a
Acknowledgment. We thank the Natural Sciences and
Engineering Research Council of Canada and the University
of British Columbia for financial support and Johnson Matthey
Ltd. and Colonial Metals Inc. for the loan of RuCl3‚3H2O.
Supporting Information Available: Table 2 (bond lengths and
angles) and tables of crystallographic data, atomic coordinates and
equivalent isotropic thermal parameters, hydrogen atom parameters,
anisotropic thermal parameters, complete bond lengths and angles,
torsion angles, intermolecular contacts, and least-square planes for the
structure of 2b (12 pages). Ordering information is given on any current
masthead page.
IC9707772
(6) Osakada, K.; Yamamoto, T.; Yamamoto, A. Inorg. Chim. Acta 1985,
105, L9.
(7) Edwards, T. H.; Moncur, N. K.; Snyder, L. E. J. Chem. Phys. 1967,
46, 2139.
(8) Schutte, R. P.; Rettig, S. J.; James, B. R. Can. J. Chem. 1996, 74,
2064.
(9) (a) Mudalige, D. C. Ph.D. Dissertation, University of British Columbia,
1994. (b) Mudalige, D. C.; James, B. R.; Cullen, W. R.; Rettig, S. J.
To be published.