Ruthenium(II) Complexes with NS2 Pyridine-Based Dithia-Containing Ligands. Proposed Possible Structural Isomers and X-ray Confirmation of Their Existence

Article abstract of DOI:10.1021/ic970829n

Ligands LX of the type NS₂ with S-aryl and S-alkyl substituents which incorporate the unit 2,6-bis(thiomethyl)pyridine are produced. Their reaction with [RuCl₂(PPh₃)₃] and [RuCl₂(DMSO)₄] produces the first reported Ru(II)/ NS₂ complexes. They present the general formulas [RuCl₂(LX)L′], where L′ = PPh₃ or DMSO. Several isomers are possible; however only two have been found in each reaction. The ¹H NMR spectra show that the H_aH_b proton atoms of the pyridine-CH_aH_b-thioether unit are nonisochronous. A Δδ(H_aH_b) value close to 1 ppm is observed for the cis complexes while this is smaller for the trans analogues. The possible distinct isomere are discussed in terms of steric effects. It is hypothesized that the trans-dl, the trans-meso, and the cis-meso-E would be the structures more favored. Those structures have been confirmed by X-ray diffraction analysis of trans-dl-[RuCl₂)(DMSO)]·0.5MeOH, cis-(RuCl₂(L5)(PPh₃]·CH₂Cl₂, and trans-meso-[RuCl₂(L6)(PPh₃)]·1.5MeOH.

Full text of DOI:10.1021/ic970829n

Inorg. Chem. 1998, 37, 701-707
701
Ruthenium(II) Complexes with NS2 Pyridine-Based Dithia-Containing Ligands. Proposed
Possible Structural Isomers and X-ray Confirmation of Their Existence
Clara Vin˜as,†,‡ Pilar Angle`s,‡ Glo`ria Sa´nchez,‡ Natividad Lucena,‡ Francesc Teixidor,*,†,‡
Llu´ıs Escriche,†,§ Jaume Casabo´,†,§ Joan F. Piniella,| Angel Alvarez-Larena,|
Raikko Kiveka1s, and Reijo Sillanpa1a1#
Institut de Cie`ncia de Materials de Barcelona (CSIC) Campus de la UAB, E-08193 Bellaterra, Spain,
Departament de Qu´ımica (Unitat de Qu´ımica Inorga`nica), Universitat Auto`noma de Barcelona,
08193 Bellaterra, Spain, Departament de Geologia (Unitat de Cristal.lografia), Universitat
Auto`noma de Barcelona, 08193 Barcelona, Spain, Department of Chemistry, University of Helsinki,
Box 55, FIN 00014 Helsinki, Finland, and Department of Chemistry, University of Turku,
FIN 20500 Turku, Finland
ReceiVed July 3, 1997
Ligands LX of the type NS2 with S-aryl and S-alkyl substituents which incorporate the unit 2,6-bis(thiomethyl)-
pyridine are produced. Their reaction with [RuCl2(PPh3)3] and [RuCl2(DMSO)4] produces the first reported Ru(II)/
NS2 complexes. They present the general formulas [RuCl2(LX)L′], where L′ ) PPh3 or DMSO. Several isomers
1
are possible; however, only two have been found in each reaction. The H NMR spectra show that the HaHb
proton atoms of the pyridine-CHaHb-thioether unit are nonisochronous. A ∆δ(HaHb) value close to 1 ppm is
observed for the cis complexes while this is smaller for the trans analogues. The possible distinct isomers are
discussed in terms of steric effects. It is hypothesized that the trans-dl, the trans-meso, and the cis-meso-E would
be the structures more favored. Those structures have been confirmed by X-ray diffraction analysis of trans-
dl-[RuCl2(L1)(DMSO)]‚0.5MeOH, cis-[RuCl2(L5)(PPh3)]‚CH2Cl2, and trans-meso-[RuCl2(L6)(PPh3)]‚1.5MeOH.
Introduction
difference between the Pd(II), Pt(II), and Ru(II) salts. The
Ru(II) in [Ru(DMSO)6][BF4]2 does not have anionic coordinat-
Tridentate N3 meridionally coordinating ligands have received
great attention in recent years.1 On the contrary NS2 pyridine-
based dithia-containing ligands, although presenting the same
kind of meridional coordination, have been much less studied.2-8
This type of ligands can be produced by a central pyridine ring
bonded to two thioether-containing arms. This coordinating unit
is responsible for the formation of complexes with different
metals, principally with Cu,4 Ni,5 Pd,6 and Pt7 and to much less
extent with Fe.8 We have recently shown the singular coordi-
nating ability of NS2(S-aryl) ligands incorporating the moiety
2,6-bis(thiomethyl)pyridine. It has been proven that Pd(II) and
Pt(II) induce acidity to the pyridine-thioether bridging -CH2
groups in ligands L1 and L3 (see ligands L1-L7 in Scheme
1), providing a route to anionic ligands which are capable of
partly compensating the positive charge of the metal M(II).9,10
A similar situation had been previously suggested with
[Ru(DMSO)6][BF4]2 and L1.9 There was however a main
ing ligands, while these are present in the Pd(II) and Pt(II)
sources, [PdCl2(CH3CN)2] and [NH4]2[PtCl4], respectively.
(2) (a) Vo¨gtle, F.; Weber, E. Angew. Chem., Int. Ed. 1974, 13, 149. (b)
Reddy, P. J.; Ravichandran, V.; Chacko, K. K.; Weber, E.; Saenger,
W. Acta Crystallogr. 1989, C45, 1871. (c) Fronczek, F. R. Am. Cryst.
Assoc. 1982, 10, Ser. 2, 27. (d) Newkome, G. R.; Pappalardo, S.;
Fronczek, F. R. J. Am. Chem. Soc. 1983, 105, 5152. (e) Weber, G.;
Jones, P. G.; Sheldrick, G. M. Acta Crystallogr., Sect. C 1983, 39,
389. (f) Berg, J. M.; Holm, R. H. Inorg. Chem. 1983, 22, 1768. (g)
Hildebrand, U.; Ockerls, W.; Lex, J.; Budzikiewicz, H. Phosphorus
Sulfur 1983, 16, 361. (h) Newkome, G. R.; Gupta, V. K.; Fronczek,
F. R.; Pappalardo, S. Inorg. Chem. 1984, 23, 2400. (i) Fukazawa, Y.;
Usui, S.; Shiokawa, T.; Tsuchiya, J. Chem. Lett. 1986, 641. (j)
Ferguson, G.; Matthes, K. E.; Parker, D. J. Chem. Soc., Chem.
Commun. 1987, 1350. (k) Helps, I. M.; Matthes, K. E.; Parker, D.;
Ferguson, G. J. Chem. Soc., Dalton Trans. 1989, 915. (l) Ferguson,
G.; Matthes, K. E.; Parker, D. Angew. Chem., Int. Ed. Engl. 1987, 26,
1162. (m) Salata, C. A.; Van Engen, D.; Burrows, C. J. J. Chem. Soc.,
Chem. Commun. 1988, 579. (n) Sillanpa¨a¨, R.; Kiveka¨s, R.; Escriche,
L.; Sa´nchez-Castello´, G.; Teixidor, F. Acta Crystallogr., Sect. C 1994,
50, 1284. (o) Ferguson, G.; Craig, A.; Parker, D.; Matthes, K. E. Acta
Crystallogr., Sect. C 1989, 45, 741.
(3) (a) Girmay, B.; Kilburn, J. D.; Underhill, A. E.; Varma, K. S.;
Hursthouse, M. B.; Harman, M. E.; Becher, J.; Bojesen, G. J. Chem.
Soc., Chem. Commun. 1989, 1406. (b) Teixidor, F.; Escriche, L.;
Rodriguez, I.; Casabo, J.; Rius, J.; Molins, E.; Martinez, B.; Miravitlles,
C. J. Chem. Soc., Dalton Trans. 1989, 1381. (c) Sobhia, M. E.;
Panneerselvam, K.; Chacko, K. K.; Suh, I. H.; Weber, E.; Reutel, C.
Inorg. Chim. Acta 1992, 194, 93. (d) Kim, D. H.; Lee, S. S.; Whang,
D.; Kim, K. Bioorg. Med. Chem. Lett. 1993, 3, 263. (e) Hildebrand,
U. H. W.; Lex, J. Z. Naturforsch., B 1989, 44, 475. (f) Casabo, J.;
Escriche, L.; Alegret, S.; Jaime, C.; Perez-Jimenez, C.; Mestres, L.;
Rius, J.; Molins, E.; Miravitlles, C.; Teixidor, F. Inorg. Chem. 1991,
30, 4931. (g) Reddy, P. J.;. Ravichandran, V.; Chacko, K. K.; Weber,
E.; Saenger, W. Acta Crystallogr., Sect. C 1989, 45, 1871. (h)
Lemmerz, R.; Nieger, M.; Vo¨gtle, F. Chem. Ber. 1994, 127, 1147. (i)
Adatia, T.; Beynek, N.; Murphy, B. P. Polyhedron 1995, 14, 335.
† On the occasion of the 80th birthday of our teacher Prof. Heribert
Barrera i Costa, in recognition of his outstanding personal and professional
merits.
‡ Campus de la UAB. E-mail: teixidor@icmab.es.
§ Departament de Qu´ımica, Universitat Auto`noma de Barcelona.
| Departament de Geologia, Universitat Auto`noma de Barcelona.
University of Helsinki.
# University of Turku.
(1) (a) Sauvage, J. P.; Collin, J. P.; Chambron, J. C.; Guillerez, S.; Coudret,
C.; Valzani, V.; Barigelletti, F.; De Cola, L.; Flamigni, L. Chem. ReV.
(Washington, D.C.) 1994, 94, 993. (b) Juris, A.; Balzani, V.;
Bariggelletti, F.; Campagna, S.; Belser, P.; Von Zelewsky, A. Coord.
Chem. ReV. 1988, 84, 85. (c) Hung, C. Y.; Wang, T. L.; Jang, Y.;
Kim, W. Y.; Schmehl, R. H.; Thummel, R. P. Inorg. Chem. 1996, 35,
5953. (d) Nishiyama, H.; Itoh, Y.; Matsumoto, H.; Park, S. B.; Itoh,
K. J. Am. Chem. Soc. 1994, 116, 2223.
S0020-1669(97)00829-X CCC: $15.00 © 1998 American Chemical Society
Published on Web 02/05/1998

702 Inorganic Chemistry, Vol. 37, No. 4, 1998
Vin˜as et al.
Scheme 1. Synthetic Procedure To Yield the Ligands LX
(LX ) L1-L7; o ) Ortho, m ) Meta, and p ) Para
Positions)
Figure 1. Molecular drawing of L8.
scribed previously.13 2,6-Bis((ethylthio)methyl)pyridine (L8) was
synthesized as reported.14 The starting ruthenium complexes
[RuCl2(PPh3)3]15 and [Ru Cl2(DMSO)4]16 were synthesized as reported.
Microanalyses were performed using a Perkin-Elmer 240B micro-
analyzer. IR spectra were obtained as KBr pellets on a Nicolet 710-
1
FT spectrophotometer. The H, 13C{1H}, and 31P{1H} NMR spectra
were recorded on Bruker spectrometers; chemical shifts are given in
1
ppm. Chemical shift values for H NMR spectra were referenced to
an internal standard of SiMe4 in deuterated solvents. Chemical shift
values for 31P{1H} NMR spectra were referenced relative to external
85% H3PO4.
All ligands and complexes were synthesized under a dinitrogen
atmosphere by employing Schlenk techniques. Solvents were placed
under vacuum to eliminate dissolved oxygen.
Thus, it was important to find the role of these ligands. Besides,
no structural information about Ru complexes with the NS2(S-
aryl) or -(S-alkyl) coordinating unit was available. This
prompted us to study the coordinating behavior of these ligands
and the physical characteristics of the resulting Ru(II) com-
plexes. Ligands L1-L8 (L8 being an NS2(S-alkyl) derivative;
see Figure 1) were chosen to permit adequate comparison.
Ligands L1-L3 are chemically very similar although they
present clear differences due to the -CO2Me group disposition
in the aromatic ring. On the contrary ligands L4-L7 are
structurally very similar but with distinct electronic properties.
This work also aims at comparing NS2(S-aryl), L1-L7, with
NS2(S-alkyl), L8, toward Ru(II) coordination and to see the
influence of ancillary ligands. The preparation of the complexes
along with the nature and identification of the possible isomers
is described in this paper.
2,6-Bis(((3′-(methoxycarbonyl)phenyl)thio)methyl)pyridine (L2).
To a stirred solution of sodium metal (0.32 g, 13 mmol) in methanol
(25 mL) was added 3-mercaptobenzoic methyl ester, and the mixture
was stirred for a further 10 min. The solution was then added to another
one of 2,6-bis(bromomethyl)pyridine (1.73 g, 6.5 mmol) in methanol
(25 mL). The mixture was heated at 30-35 °C for 30 min and then
cooled to room temperature. The methanol was evaporated under
reduced pressure. The resulting yellow residue was extracted with
diethyl ether (50 mL), and the organic layer was washed twice with
distilled water (2 × 50 mL), dried (MgSO4), and vacuum evaporated
to afford L2 as an oil which solidified upon contact with petroleum
ether at 5 °C. Yield: 2.12 g (74%). FTIR (KBr): ν(CdO) 1718 cm-1
.
1H NMR (CDCl3, 300 MHz): δ 3.89 (s, 6H, COOCH3), 4.29 (s, 4H,
py-CH2-S), 7.19 (d, 3J(H,H) ) 7.9 Hz, 2H, H3py), 7.29 (dd, 3J(H,H)
) 7.6 Hz, 3J(H,H) ) 7.9 Hz, 2H, H5Ph), 7.47 (br d, 3J(H,H) ) 7.9 Hz,
2H, H6Ph), 7.54 (t, 3J(H,H) ) 7.9 Hz, 1H, H4py), 7.82 (br d, 3J(H,H) )
7.6 Hz, 2H, H4Ph), 8.04 (br s, 2H, H2Ph). 13C{1H} NMR (CDCl3, 75
MHz): δ 39.93 (s, py-CH2-S), 52.24 (s, COOCH3), 121.48-156.94
(Caryl), 166.51 (s, COOCH3). Anal. Calcd for C23H21NO4S2: C, 62.85;
H, 4.82; N, 3.19; S, 14.59. Found: C, 62.70; H, 4.86; N, 3.22; S,
13.98.
Experimental Section
Materials and Methods. 2,6-Bis(bromomethyl)pyridine was syn-
thesized as reported.11 The 3- and 4-mercaptobenzoic methyl esters
were synthesized as reported,12 and the other mercapto derivatives were
used as received. 2,6-Bis(((2′-(methoxycarbonyl)phenyl)thio)methyl)-
pyridine (L1), 2,6-bis((phenylthio)methyl)pyridine (L5) and 2,6-bis-
(((4′-chlorophenyl)thio)methyl)pyridine (L6) were synthesized as de-
2,6-Bis(((4′-(methoxycarbonyl)phenyl)thio)methyl)pyridine (L3).
L3 was prepared by following the procedure for L2, using 4-mercap-
tobenzoic methyl ester (1.91 g, 11.4 mmol), sodium metal (0.26 g, 11.4
mmol), and 2,6-bis(bromomethyl)pyridine (1.51 g, 5.7 mmol). Yield:
1.61 g (64%). FTIR (KBr): ν(CdO) 1708 cm-1 1H NMR (CDCl3,
.
(4) (a) Weber, G. Inorg. Chim. Acta 1982, 58, 27. (b) Escriche, L.; Sanz,
M.; Casabo, J.; Teixidor, F.; Molins, E.; Miravitlles, C. J. Chem. Soc.,
Dalton Trans. 1989, 1739. (c) Masuda, H.; Sugimori, T.; Kohzuma,
T.; Odani, A.; Yamauchi, O. Bull. Chem. Soc. Jpn. 1992, 65, 786. (d)
Sillanpa¨a¨, R.; Kiveka¨s, R.; Escriche, L.; Casabo, J.; Sa´nchez-Castello´,
G. Acta Crystallogr., Sect. C 1994, 50, 1062.
250 MHz): δ 3.88 (s, 6H, COOCH3), 4.32 (s, 4H, py-CH2-S), 7.27
(d, 3J(H,H) ) 7.4 Hz, 2H, H3py), 7.35 (d, 3J(H,H) ) 7.8 Hz, 4H, H2Ph),
3
3
7.56 (t, J(H,H) ) 7.4 Hz, 1H, H4py), 7.87 (d, J(H,H) ) 7.8 Hz, 4H,
3Ph). 13C{1H} NMR (CDCl3, 62.5 MHz): δ 38.62 (s, py-CH2-S),
H
(5) (a) Constable, E. C.; Lewis, J.; Marquez, V. E.; Raithby, P. R. J. Chem.
Soc., Dalton Trans. 1986, 1747. (b) Kruger, H. J.; Holm, R. H. J.
Am. Chem. Soc. 1990, 112, 2955. (c) Kruger, H. J.; Holm, R. H. Inorg.
Chem. 1989, 28, 1148.
(6) (a) Espinet, P.; Lorenzo, C.; Miguel, J. A.; Bois, C.; Jeannin, Y. Inorg.
Chem. 1994, 33, 2052. (b) Sato, M.; Asano, H.; Akabori, S. J.
Organomet. Chem. 1993, 105, 452.
(7) (a) Marangoni, G.; Pitteri, B.; Bertolasi, V.; Ferretti, V.; Gilli, P.
Polyhedron 1993, 12, 1669. (b) Abel, E. W.; Heard, P. J.; Orrell, K.
G.; Hursthouse, M. B.; Mazid, M. A. J. Chem. Soc., Dalton Trans.
1993, 3795.
52.02 (s, COOCH3), 121.42-156.62 (Caryl), 166.65 (s, COOCH3). Anal.
Calcd for C23H21NO4S2: C, 62.85; H, 4.82; N, 3.19; S, 14.59. Found:
C, 62.17; H, 4.78; N, 3.07; S, 13.87.
2,6-Bis(((4′-methoxyphenyl)thio)methyl)pyridine (L4). L4 was
prepared by following the procedure for L2 using 4-methoxyben-
zenethiol (1.09 g 7.6 mmol), sodium metal (0.17 g, 7.6 mmol), and
2,6-bis(bromomethyl)pyridine (1.01 g, 3.8 mmol). Yield: 1.45 g (88%).
1H NMR (CDCl3, 300 MHz): δ 3.75 (s, 6H, CH3-O), 4.15 (s, 4H,
3
3
py-CH2-S), 6.77 (d, J(H,H) ) 8.8 Hz, 4H, H3Ph), 7.03 (d, J(H,H)
(8) Hildebrand, U.; Lex, J.; Taraz, K.; Winkler, S.; Ockels, W.; Budzik-
iewicz, H. Z. Naturforsch., B 1984, 39, 1607.
(9) Teixidor, F.; Sa´nchez, G.; Lucena, N.; Escriche, Ll.; Kiveka¨s, R.;
Casabo´, J. J. Chem. Soc., Chem. Commun. 1992, 163.
(10) Vin˜as, C.; Angle`s, P.; Teixidor, F.; Sillanpa¨a¨, R.; Kiveka¨s, R. Chem.
Commun. 1996, 715.
(11) Baker, W.; Buggle, K. M.; McOmie, J. F. W.; Watkins, D. A. J. Chem.
Soc. 1958, 3594.
(12) Wiley, P. F. J. Org. Chem. 1951, 16, 810.
(13) Teixidor, F.; Sa´nchez-Castello´, G.; Lucena, N.; Escriche, Ll.; Kiveka¨s,
R.; Sundberg, M.; Casabo´, J. Inorg. Chem. 1991, 30, 4931.
(14) Teixidor, F.; Escriche, Ll.; Casabo´, J.; Molins E.; Miravitlles, C. Inorg.
Chem. 1986, 25, 4060.
(15) Stephenson, T. A.; Wilkinson, G. J. Inorg. Nucl. Chem. 1966, 28,
945.
(16) Evans, I. P.; Spencer, A.; Wilkinson, G. J. Chem. Soc., Dalton Trans.
1973, 204.

Ru(II) Complexes with NS2 Ligands
Inorganic Chemistry, Vol. 37, No. 4, 1998 703
3
) 7.7 Hz, 2H, H3py), 7.24 (d, J(H,H) ) 8.8 Hz, 4H, H2Ph), 7.48 (t,
Hz, py-C(HA)(HB)-S), 6.53-7.68 (m, Haryl); δ 2nd (50%) 1.59 (br s,
3J(H,H) ) 7.7 Hz, 1H, H4py). 13C{1H} NMR (CDCl3, 75 MHz): δ
41.8 (s, py-CH2-S), 55.27 (s, CH3-O), 114.53-159.24 (Caryl). Anal.
Calcd for C21H21NO2S2: C, 65.77; H, 5.52; N, 3.65; S, 16.72. Found:
C, 65.60; H, 5.66; N, 3.62; S, 16.34.
H2O), 3.75 (s, CH3-O), 4.90 (br d, J(H,H) ) 14.4 Hz, py-C(HA)-
2
2
(HB)-S), 4.99 (br d, J(H,H) ) 14.4 Hz, py-C(HA)(HB)-S), 6.53-
7.68 (m, Haryl). 31P{1H} NMR (CDCl3, 121.5 MHz): δ 44.70, 47.32
(s, PPh3). Anal. Calcd for C39H40Cl2NO4PRuS2: C, 54.90; H, 4.72;
N, 1.64; S, 7.51. Found: C, 55.28; H, 4.30; N, 1.64; S, 7.05.
[RuCl2(L4)(DMSO)]. [RuCl2(L4)(DMSO)] was prepared by fol-
lowing the procedure for [RuCl2(L2)(PPh3)] using L4 (76 mg, 0.1
mmol) and [RuCl2(DMSO)4] (96 mg, 0.1 mmol). An orange solid was
obtained. Yield: 51 mg (75%). 1H NMR (CDCl3, 300 MHz): δ 1st
dias. (26%) 3.02 (s, (CH3)2SO), 3.79 (s, CH3-O), 4.96 (s, py-CH2-
S), 6.80-7.76 (m, Haryl); δ 2nd dias. (74%) 3.15 (s, (CH3)(CH3)SO),
2,6-Bis(((4′-nitrophenyl)thio)methyl)pyridine (L7). To a stirred
solution of 98% sodium hydroxide (1.8 g, 45 mmol) in ethanol (200
mL) was added p-nitrothiophenol (7.0 g, 45 mmol), and the mixture
was heated to reflux for 30 min. After this time the mixture is cooled
to 0 °C. Then, a solution of 2,6-bis(bromomethyl)pyridine (5.38 g, 20
mmol) in ethanol (100 mL) was added. After addition, an orange
precipitate appeared. The mixture was stirred at 0 °C for 1 h. The
precipitate was filtered out, washed with water, redissolved in THF,
dried (MgSO4), and vacuum evaporated to afford L7 as an orange solid.
Yield: 4.68 g (56%). 1H NMR ((CD3)2CO, 400 MHz): δ 4.52 (s,
4H, py-CH2-S), 7.47 (d, 3J(H,H) ) 7.6 Hz, 2H, H3py), 7.65 (d, 3J(H,H)
2
3.37 (s, (CH3)(CH3)SO), 3.77 (s, CH3-O), 4.47 (d, J(H,H) ) 16.6
Hz, py-C(HA)(HB)-S), 5.32 (d, 2J(H,H) ) 16.6 Hz, py-C(HA)(HB)-
S), 6.80-7.76 (m, Haryl). 13C{1H} NMR (CDCl3, 75 MHz): δ 46.41,
46.97 (s, (CH3)2SO), 50.62, 50.84 (s, py-CH2-S), 55.27 (s, CH3-O),
114.41-161.88 (Caryl). Anal. Calcd for C23H27Cl2NO3RuS3: C, 43.60;
H, 4.30; N, 2.21; S, 15.15. Found: C, 43.20; H, 4.10; N, 2.20; S, 15.40.
[RuCl2(L5)(PPh3)]‚MeOH. The ligand L5 (34 mg, 0.1 mmol)
dissolved in methanol (20 mL) was added to a suspension of [RuCl2-
(PPh3)3] (100 mg, 0.1 mmol) in methanol (20 mL). The mixture was
refluxed for 30 min. The hot solution was filtered and then cooled to
room temperature. After slow and partial evaporation of the solvent,
a crystalline orange precipitate was obtained. Yield: 58 mg (71%).
1H NMR (CDCl3, 400 MHz): δ 1st dias. (44%) 3.48 (s, CH3-OH),
4.34 (br d, 2J(H,H) ) 18.4 Hz, py-C(HA)(HB)-S), 5.48 (br d, 2J(H,H)
) 18.4 Hz, py-C(HA)(HB)-S), 7.01-7.67 (m, Haryl); δ 2nd (56%)
3.48 (s, CH3-OH), 4.97 (br s, py-CH2-S), 7.01-7.67 (m, Haryl).
13C{1H} NMR (CDCl3, 100 MHz): δ 52.25, 52.72 (s, py-CH2-S),
119.96-136.00 (Caryl). 31P{1H} NMR (CDCl3, 162 MHz): δ 44.74,
47.93 (s, PPh3). Anal. Calcd for C38H36Cl2NOPRuS2: C, 57.79; H,
4.59; N, 1.77; S, 8.12; Cl, 8.98. Found: C, 57.82; H, 4.39; N, 1.77;
S, 8.17; Cl, 9.22. Crystals suitable for X-ray diffraction were grown
from dichloromethane/hexane.
3
) 8.9 Hz, 4H, H2Ph), 7.77 (t, J(H,H) ) 7.6 Hz, 1H, H4py), 8.08 (d,
3J(H,H) ) 8.9 Hz, 4H, H3Ph).13C{1H} NMR ((CD3)2CO, 400 MHz): δ
37.11 (s, py-CH2-S), 121.46 (s, C3py), 123.26 (s, C3Ph), 126.21 (s,
C
C
2Ph), 137.66 (s, C4py), 144.74 and 146.89 (C4Ph and C1Ph), 156.28 (s,
2py). Anal. Calcd for C19H15N3O4S2: C, 55.20; H, 3.63; N, 10.17;
S, 15.49. Found: C, 55.32; H, 3.78; N, 9.92; S, 15.26.
[RuCl2(L1)(DMSO)]. The ligand L1 (100 mg, 0.23 mmol) was
added to a suspension of [RuCl2(DMSO)4] (110 mg, 0.23 mmol) in
methanol (25 mL). The mixture was heated under reflux for 10 h.
The solution was allowed to stand overnight, and a solid was obtained
in microcrystalline form, which was filtered out and washed with
methanol (1 mL). Yield: 149 mg (94%). FTIR (KBr): ν(CdO) 1721
cm-1
.
1H NMR (CDCl3, 400 MHz): δ 1st dias. (60%) 3.95 (s,
COOCH3), 4.41 (d, 2J(H,H) ) 17 Hz, py-C(HA)(HB)-S), 5.33 (d,
2J(H,H) ) 17 Hz, py-C(HA)(HB)-S), 7.21-8.11 (m, Haryl); δ 2nd dias.
(40%) 3.95 (s,COOCH3), 4.88 (d, 2J(H,H) ) 15 Hz, py-C(HA)(HB)-
S), 5.10 (d, 2J(H,H) ) 15 Hz, py-C(HA)(HB)-S), 7.21-8.11 (m, Haryl).
Anal. Calcd for C25H27Cl2NO5RuS3: C, 43.54; H, 3.92; N, 2.03; S,
13.93; Cl, 10.30. Found: C, 43.12; H, 3.99; N, 2.00; S, 13.78; Cl,
10.00. Crystals suitable for X-ray diffraction were grown from
methanol.
[RuCl2(L6)(PPh3)]‚MeOH. [RuCl2(L6)(PPh3)]‚MeOH was pre-
pared by following the procedure for [RuCl2(L5)(PPh3)]‚MeOH using
L6 (40 mg, 0.1 mmol) and [RuCl2(PPh3)3] (100 mg, 0.1 mmol). After
slow and partial evaporation of the solvent a crystalline orange
precipitate was obtained. Yield: 60 mg (68%). 1H NMR (CDCl3, 400
[RuCl2(L2)(PPh3)]. The ligand L2 (45 mg, 0.1 mmol) and [RuCl2-
(PPh3)3] (100 mg, 0.1 mmol) were added to a two-necked round-bottom
flask. To this mixture, 5 mL of toluene was added, and the solution
was heated under reflux for 1 h. After this time, the orange solid was
filtered out, washed with diethyl ether and ethanol, and dried under
vacuum. Yield: 40 mg (46%). 1H NMR (CDCl3, 300 MHz): δ 1st
2
MHz): δ 1st dias. (40%) 3.46 (s, CH3-OH), 4.31 (br d, J(H,H) )
16.0 Hz, py-C(HA)(HB)-S), 5.46 (br d, 2J(H,H) ) 16.0 Hz, py-C(HA)-
(HB)-S), 6.99-7.97 (m, Haryl); δ 2nd (60%) 3.46 (s, CH3-OH), 4.90
2
2
(br d, J(H,H) ) 14.8 Hz, py-C(HA)(HB)-S), 5.00 (br d, J(H,H) )
14.8 Hz, py-C(HA)(HB)-S), 6.99-7.97 (m, Haryl). 13C{1H} NMR
(CDCl3, 100 MHz): δ 52.28, 52.80 (s, py-CH2-S), 120.21-161.40
(Caryl). 31P{1H} NMR (CDCl3, 162 MHz): δ 44.19, 47.40 (s, PPh3).
Anal. Calcd for C38H34Cl4NOPRuS2: C, 53.15; H, 3.99; N, 1.63; S,
7.47; Cl, 16.50. Found: C, 52.75; H, 3.86; N, 1.62; S, 7.30; Cl, 15.72.
Crystals suitable for X-ray diffraction were grown from methanol.
[RuCl2(L7)(PPh3)]‚MeOH. [RuCl2(L7)(PPh3)]‚MeOH was pre-
pared following the procedure for [RuCl2(L5)(PPh3)]‚MeOH using L7
(100 mg, 0.2 mmol) and [RuCl2(PPh3)3] (25 mg, 0.2 mmol). A brown
precipitate was obtained, yield: 42 mg (20%). 1H NMR (CDCl3, 400
2
dias. (63%) 3.87 (s, COOCH3), 4.39 (br d, J(H,H) ) 16.5 Hz, py-
2
C(HA)(HB)-S), 5.53 (br d, J(H,H) ) 16.5 Hz, py-C(HA)(HB)-S),
7.21-7.86 (m, Haryl); δ 2nd dias. (37%) 3.87 (s, COOCH3), 5.00 (br d,
2J(H,H) ) 15.4 Hz, py-C(HA)(HB)-S), 5.07 (br d, J(H,H) ) 15.4
2
Hz, py-C(HA)(HB)-S), 7.21-7.86 (m, Haryl). 13C{1H} NMR (CDCl3,
75 MHz): δ 51.93 (s, py-(CH2-S)A), 52.52 (s, py-(CH2-S)B), 52.17
(s, COOCH3), 120.51-161.44 (Caryl), 166.06 (s, COOCH3). 31P{1H}
NMR (CDCl3, 121.5 MHz): δ 42.70, 46.28 (s, PPh3). Anal. Calcd
for C41H36Cl2NO4PRuS2: C, 56.36; H, 4.15; N, 1.60; S, 7.34. Found:
C, 54.93; H, 4.14; N, 1.61; S, 6.87.
2
[RuCl2(L3)(PPh3)]. [RuCl2(L3)(PPh3)] was prepared by following
the procedure for [RuCl2(L2)(PPh3)] using L3 (45 mg, 0.1 mmol) and
[RuCl2(PPh3)3] (100 mg, 0.1 mmol). Yield: 67 mg (77%). 1H NMR
(CDCl3, 300 MHz): δ 1st dias. (45%) 3.89 (s, COOCH3), 4.42 (br d,
MHz): δ 1st dias. (40%) 3.43 (s, CH3-OH), 4.44 (br d, J(H,H) )
16.0 Hz, py-C(HA)(HB)-S), 5.52 (br d, 2J(H,H) ) 16.0 Hz, py-C(HA)-
(HB)-S), 6.99-7.97 (m, Haryl); δ 2nd (60%) 3.43 (s, CH3-OH), 5.01
2
2
(br d, J(H,H) ) 14.8 Hz, py-C(HA)(HB)-S), 5.10 (br d, J(H,H) )
14.8 Hz, py-C(HA)(HB)-S), 6.99-7.97 (m, Haryl). 31P{1H} NMR
(CDCl3, 162 MHz) δ: 41.90, 45.92 (s, PPh3). Anal. Calcd for
C38H34Cl2N3O5PRuS2: C, 51.88; H, 3.89; N, 4.77; S, 7.28; Cl, 8.06.
Found: C, 52.81; H, 3.69; N, 4.40; S, 6.37; Cl, 8.42.
2J(H,H) ) 13.6 Hz, py-C(HA)(HB)-S), 5.53 (br d, J(H,H) ) 13.6
2
Hz, py-C(HA)(HB)-S), 7.01-7.80 (m, Haryl); δ 2nd dias. (55%) 3.89
(s, COOCH3), 5.04 (br s, py-CH2-S), 7.01-7.80 (m, Haryl). 13C{1H}
NMR (CDCl3, 75 MHz): δ 51.56 (s, py-(CH2-S)A), 51.86 (s, py-
(CH2-S)B), 52.15 (s, COOCH3), 120.42-134.68 (Caryl), 166.39 (s,
COOCH3). 31P{1H} NMR (CDCl3, 121.5 MHz): δ 42.27, 45.89 (s,
PPh3). Anal. Calcd for C41H36Cl2NO4PRuS2: C, 56.36; H, 4.15; N,
1.60; S, 7.34. Found: C, 56.60; H, 4.34; N, 1.54; S, 7.10.
[RuCl2(L4)(PPh3)]‚2H2O. [RuCl2(L4)(PPh3)]‚2H2O was prepared
by following the procedure for [RuCl2(L2)(PPh3)] using L4 (38 mg,
0.1 mmol) and [RuCl2(PPh3)3] (100 mg, 0.1 mmol). A brown-green
solid was obtained. Yield: 34 mg (42%). 1H NMR (CDCl3, 300
MHz): δ 1st dias. (50%) 1.59 (br s, H2O), 3.75 (s, CH3-O), 4.29 (br
d, 2J(H,H) ) 16.1 Hz, py-C(HA)(HB)-S), 5.49 (br d, 2J(H,H) ) 16.1
[RuCl2(L8)(PPh3)]‚MeOH. [RuCl2(L8)(PPh3)]‚MeOH was pre-
pared by following the procedure for [RuCl2(L5)(PPh3)]‚MeOH using
L8 (23 mg, 0.1 mmol) and [RuCl2(PPh3)3] (100 mg, 0.1 mmol). After
slow and partial evaporation of the solvent a microcrystalline yellow-
orange precipitate was obtained. Yield: 34 mg (48%). 1H NMR
(CDCl3, 400 MHz): δ 1st dias. (62%) 1.12 (t, 3J(H,H) ) 6.5 Hz, CH3-
3
CH2-S), 2.34 (q, J(H,H) ) 6.5 Hz, CH3-CH2-S), 3.47 (s, CH3-
OH), 4.08 (d, 2J(H,H) ) 16.2 Hz, py-C(HA)(HB)-S), 5.00 (d, 2J(H,H)
) 16.2 Hz, py-C(HA)(HB)-S), 7.26-7.76 (m, Haryl); δ 2nd (38%)
3
2
1.05 (t, J(H,H) ) 6.5 Hz, CH3-CH2-S), 2.17 (dq, J(H,H) ) 13.4

704 Inorganic Chemistry, Vol. 37, No. 4, 1998
Vin˜as et al.
Table 1. Crystallographic Data for trans-dl-[RuCl2(L1)(DMSO)]‚0.5MeOH, cis-[RuCl2(L5)(PPh3)]‚CH2Cl2, and
trans-meso-[RuCl2(L6)(PPh3)]‚1.5MeOH
compd
trans-dl-[RuCl2(L1)(DMSO)]‚
cis-[RuCl2(L5)(PPh3)]‚
CH2Cl2
C38H34Cl4NPRuS2
842.62
trans-meso-[RuCl2(L6)(PPh3)]‚
0.5MeOH
C25.5H29Cl2NO5.5RuS3
595.2
1.5MeOH
C38.5H36Cl4NO1.5PRuS2
874.64
chem formula
fw
T, °C
λ, Å
cryst syst
space group
a, Å
b, Å
c, Å
20
20
23
0.710 69
monoclinic
C2/c (No. 15)
36.320(4)
10.744(3)
15.781(2)
110.06(1)
5785(2)
8
1.621
9.82
0.907-1.000
2872
0.710 69
monoclinic
P21/n (No. 14)
10.078(3)
11.458(2)
31.886(3)
96.72(1)
3657(1)
0.710 69
monoclinic
P21/n (No. 14)
16.517(2)
12.987(3)
19.650(2)
110.332(8)
3952(1)
â, deg
V, Å3
Z
d
4
4
calcd, g cm-3
1.531
9.08
0.883-0.998
1712
1.045
0.0346
0.1007
1.470
8.46
0.902-1.000
1780
0.960
0.0563
0.1467
µ, cm-1
transm coeff
F(000)
goodness-of-fit on F2
1.057
0.0304
0.0742
Ra
wRb
a R ) ∑||Fo| - |Fc||/Σ|Fo|. b wR ) [∑w(|Fo | - |Fc2|)2/∑w|Fo | ]1/2
.
2
2 2
Hz, 3J(H,H) ) 6.5 Hz, CH3-C(H1)(H2)-S), 2.68 (dq, 2J(H,H) ) 13.4
NaOH/MeOH yields podand ligands containing the coordinating
group NS2(S-aryl): 2,6-bis(((3-methoxycarbonyl)phenyl)thio)-
methyl)pyridine (L2); 2,6-bis(((4-methoxycarbonyl)phenyl)thio)-
methyl)pyridine (L3); 2,6-bis(((4-methoxyphenyl)thio)methyl)-
pyridine (L4); 2,6-bis(((4-nitrophenyl)thio)methyl)pyridine (L7).
Scheme 1 exemplifies these reactions.
A similar reaction leading to the NS2(S-alkyl)ligand L8
containing the ethyl group bonded to S (Figure 1) has also been
conducted.
3
Hz, J(H,H) ) 6.5 Hz, CH3-C(H1)(H2)-S), 3.47 (s, CH3-OH), 4.43
2
2
(d, J(H,H) ) 15.2 Hz, py-C(HA)(HB)-S), 4.70 (d, J(H,H) ) 15.2
Hz, py-C(HA)(HB)-S), 7.26-7.76 (m, Haryl). 13C{1H} NMR (CDCl3,
100 MHz): δ 12.56, 12.72 (s, CH3-CH2-S), 28.43, 29.53 (s, CH3-
CH2-S), 46.11, 47.52 (s, py-CH2-S), 120.58-161.04 (Caryl). 31P{1H}
NMR (CDCl3, 162 MHz): δ 45.63, 47.03 (s, PPh3). Anal. Calcd for
C30H36Cl2NOPRuS2: C, 51.94; H, 5.23; N, 2.01; S, 9.24; Cl, 10.22.
Found: C, 52.44; H, 5.18; N, 1.99; S, 9.24; Cl, 10.47.
X-ray Studies. Single-crystal data collections for the compounds
trans-dl-[RuCl2(L1)(DMSO)]‚0.5MeOH and trans-meso-[RuCl2(L6)-
(PPh3)]‚1.5MeOH were carried out on a Rigaku AFC-5S diffractometer,
while that for the cis-[RuCl2(L5)(PPh3)]‚CH2Cl2 were made with a
CAD4 Enraf-Nonius diffractometer. Single-crystal data collections for
each compound were performed at ambient temperature using graphite-
monochromatized Mo KR radiation. A total of 4614, 4448, and 4616
observed reflections [I > 2σ(I)] were collected by the ω/2θ scan mode
for trans-dl-[RuCl2(L1)(DMSO)]‚0.5MeOH, cis-[RuCl2(L5)(PPh3)]‚-
CH2Cl2, and trans-meso-[RuCl2(L6)(PPh3)]‚1.5MeOH, respectively.
The structures were solved by direct methods by using the SHELX-
90 program17 and refined on F2 by the SHELXL-93 program.18 For
trans-dl-[RuCl2(L1)(DMSO)]‚0.5MeOH, non-hydrogen atoms were
refined with anisotropic displacement parameters and hydrogen atoms,
except those of disordered methanol molecule, were placed at their
calculated positions. Hydrogen atoms of the methanol molecule could
not be reliably positioned. For cis-[RuCl2(L5)(PPh3)]‚CH2Cl2, non-
hydrogen atoms were refined with anisotropic displacement parameters
and hydrogen atoms were placed at their calculated positions. The
asymmetric unit of trans-meso-[RuCl2(L6)(PPh3)]‚1.5MeOH contains
disordered methanol molecules in three neighboring positions. Non-
hydrogen atoms of the methanol molecules were refined with isotropic
displacement parameters, but hydrogen atoms could not be reliably
positioned. The remaining non-hydrogen atoms were refined with
anisotropic displacement parameters, and the remaining hydrogen atoms
were placed at their calculated positions. Crystallographic data and
structure refinement parameters are presented in Table 1, and selected
bond lengths and angles of the three complexes in Table 2.
The reaction of L1-L8 with [RuCl2(PPh3)3] and [RuCl2-
(DMSO)4] in a 1:1 molar ratio in methanol or toluene yielded
complexes of the stoichiometry [RuCl2(LX)L′] (where LX )
L1-L8 and L′ ) PPh3 or DMSO).
Discussion
2,6-Bis((arylthio)methyl)pyridine is prone to rearrangements
when complexed with Pd(II), Pt(II), and presumably Ru(II)
metal ions.9 The factors influencing these rearrangements have
not been studied, although it is hypothesized that the ease of
allyl formation by the pyridine-CH2-thioether moiety does
facilitate the ligand’s rearrangements.19 For better insight into
the chemistry of these NS2 pyridine-based dithia S-aryl- and
S-alkyl-containing ligands, reactions have been performed with
Ru(II) complexes incorporating bulky ligands such as PPh3 or
easily displaced ones such as DMSO. Reactions have been
carried out in toluene and methanol. Despite all these differ-
ences, the reactions have always led to octahedral Ru(II)
complexes where three of the available coordinating positions
are occupied by the unaltered NS2 ligands. The other three
positions are occupied by the two coordinating chloride anions,
leaving one position for a nonionic ligand. Thus, the complexes
present the general formulas [RuCl2(LX)L′].
The methylene py-CH2-S 1H NMR resonances, in the free
ligands, are found in the range of 4-4.3 ppm as singlets. This
implies that at room temperature both -CH2 proton atoms in
the noncomplexed ligands are equivalent. Upon complexation
Results
The reaction of 2,6-bis(bromomethyl)pyridine with thiophenol
derivatives 3-(methoxycarbonyl)thiophenol, 4-(methoxycarbon-
yl)thiophenol, 4-methoxythiophenol, and 4-nitrothiophenol in
1
this no longer is so. Typically the H NMR spectrum of the
isolated complexes displays a very similar pattern in the region
4-5.5 ppm. Two sets of doublets of doublets are found. The
(17) Sheldrick, G. M. SHELX-90. Acta Crystallogr. 1990, A46, 467.
(18) Sheldrick, G. M. SHELXL-93, Program for Crystal Structure Refine-
ment, University of Go¨ttingen, Germany, 1993.
(19) Boulton, A. J.; McKillop, A. ComprehensiVe heterocyclic chemistry;
Pergamon Press: London, 1984; Vol. 2, p 329.

Ru(II) Complexes with NS2 Ligands
Inorganic Chemistry, Vol. 37, No. 4, 1998 705
Table 2. Selected Bond Lengths (Å) and Angles (deg) for trans-dl-[RuCl2(L1)(DMSO)]‚0.5MeOH, cis-[RuCl2(L5)(PPh3)]‚CH2Cl2, and
trans-meso-[RuCl2(L6)(PPh3]‚1.5MeOH
trans-dl-[RuCl2 (L1)-
(DMSO)]‚0.5MeOH
cis-[RuCl2(L5)-
(PPh3)]‚CH2Cl2
trans-meso[RuCl2 (L6)-
(PPh3)]‚1.5MeOH
Ru-Cl(1)
Ru-Cl(2)
Ru-S(1)
Ru-S(2)
Ru-S(3)
Ru-P
2.4088(7)
2.4067(7)
2.3527(7)
2.3406(7)
2.2540(8)
2.427(1)
2.465(1)
2.332(1)
2.343(1)
2.460(1)
2.428(1)
2.345(2)
2.316(1)
2.304(1)
2.056(3)
2.329(1)
2.103(4)
Ru-N
2.079(2)
Cl(1)-Ru-Cl(2)
Cl(1)-Ru-N
Cl(2)-Ru-N
S(1)-Ru-S(2)
S(1)-Ru-N
S(2)-Ru-N
S(3)-Ru-N
P-Ru-N
177.55(3)
88.45(6)
89.21(6)
167.68(2)
83.82(6)
83.89(6)
174.44(6)
90.21(4)
173.23(9)
84.8(1)
164.66(4)
83.8(1)
171.52(4)
87.6(1)
84.7(1)
161.85(5)
82.4(1)
81.1(1)
81.12(9)
98.50(9)
178.9(1)
N-Ru-S(1)-C(7)
-22.1(1)
-21.1(1)
82.7(1)
-23.1(2)
-29.8(2)
85.3(2)
-135.6(2)
-84.7(4)
161.9(3)
-20.7(2)
-29.8(2)
88.1(2)
-136.4(2)
-87.2(5)
163.9(4)
N-Ru-S(2)-C(13)
N-Ru-S(1)-C(1)
N-Ru-S(2)-C(14)
C(1)-S(1)-C(7)-C(8)
C(14)-S(2)-C(13)-C(12)
S(3)-Ru-S(1)-C(1)
S(3)-Ru-S(2)-C(14)
P-Ru-S(1)-C(1)
84.8(1)
-85.3(2)
-82.0(2)
-101.1(1)
-91.31(9)
-176.4(2)
125.4(2)
-92.9(2)
44.5(2)
P-Ru-S(2)-C(14)
Figure 2. Schematic drawing of the cis and trans isomers of [RuCl2-
(LX)(L)].
Figure 3. Schematic drawing of the trans-meso and trans-dl isomers
of [RuCl2(LX)(L)].
outer doublet of doublets in the region show a similar pattern,
as does the inner set. Both can be interpreted as AB systems.
The total integration of the zone agrees well with the other zones
thioether inversion22 does not take place at room temperature
in these ruthenium complexes. The interpretation for the trans-
[RuCl2(LX)L′] isomer requires a noninversion at the thioether
1
in the spectrum. Consequently, the H NMR spectra can be
1
to understand the H NMR.22 Due to the relative disposition
interpreted as being the result of two isomers, whose pyridine-
CHaHb-thioether protons are chemically nonequivalent produc-
ing a geminal coupling between them.20 The graphical inter-
pretation is given in Figure 2.
If a room-temperature fast thioether inversion was considered
for the trans complex, the four methylene protons in pyridine-
CHaHb-thioether would be equivalent and only one resonance
would be found in the spectra.21 On the other hand, noniso-
chronous CHaHb would always be expected for the cis species.
The number of resonances found in the 13C{1H} NMR spectra
at the -CH2- region, near 52 ppm in the complexes, is two,
and they do not have equal intensity. This confirms the
existence of only two isomers in solution and requires that
of the -S substituents two isomers would be possible, the trans-
meso and the trans-dl, both indicated in Figure 3. The wide
shape of the 1H NMR resonances points out that in most cases
both isomers trans-dl and trans-meso coexist in solution.
A similar reasoning could be followed for the cis isomer;
however, in this case the number of possible isomers is higher
since one cis-dl and two cis-meso species designated Z and E,
in similarity to the alkene terminology, could be formed (see
Figure 4). In this case, however, only one is present in solution.
The four methylene protons are nonequivalent at the cis-dl
form; thus, four sets of groups of resonances would be expected
in its spectrum. As indicated, this is not the case, so compound
cis-dl is not present. However, some hints can be drawn about
the nonexistence of this compound. The cis-dl structure implies
that one substituent on S and the bulky ancillary ligand point
to the same direction. This situation produces an sterically
crowded region which should not be thermodynamically favor-
(20) (a) Rawle, S. C.; Sewell, T. J.; Cooper, S. R. Inorg. Chem. 1987, 26,
3769. (b) Ku¨ppers. Inorg. Chem. 1986, 25, 2400.
(21) (a) Bashall, A.; McPartlin, M.; Murphy, B. P.; Powell, H. R.; Waikar,
S. J. Chem. Soc., Dalton Trans. 1994, 1383. (b) Constable, E. C.;
Sacht, Ch.; Palo, G.; Tocher, D. A.; Truter, M. R. J. Chem. Soc., Dalton
Trans. 1993, 1307. (c) Amador, V.; Delgado, E.; Fornie´s, J.;
Herna´ndez, E.; Lalinde, E.; Moreno, M. T. Inorg. Chem. 1995, 34,
5279.
(22) Abel, E. W.; Bhargava, S. K.; Kite, K.; Orrell, K. G.; Sˇik, V.; Williams,
B. L. Polyhedron 1982, 1, 289.

706 Inorganic Chemistry, Vol. 37, No. 4, 1998
Vin˜as et al.
Table 3. ∆δ(HaHb) Observed Values for Trans and Cis Isomers
and Their Ratio in Solution
complex
∆δ cis
% cis
∆δ trans
% trans
[RuCl2(L2)(PPh3)]
[RuCl2(L3)(PPh3)]
[RuCl2(L4)(PPh3)]
[RuCl2(L4)(DMSO)]
[RuCl2(L1)(DMSO)]
[RuCl2(L5)(PPh3)]
[RuCl2(L6)(PPh3)]
[RuCl2(L7)(PPh3)]
[RuCl2(L8)(PPh3)]
1.14
1.11
1.20
0.85
0.92
1.14
1.15
1.08
0.92
63
45
50
74
60
44
40
40
62
0.07
∼0
37
55
50
26
40
56
60
60
38
0.09
0
0.22
∼0
0.1
0.09
0.27
Figure 4. Schematic drawing of the cis-dl, cis-meso-Z, and cis-meso-E
isomers of [RuCl2(LX)(L)].
Figure 5. Watch circle representations from the S-Ru-S axis of the
different isomers (R ) Ph; L ) PPh3 or DMSO).
Figure 6. ORTEP plot of complex unit of trans-dl-[RuCl2(L1)-
(DMSO)]‚0.5MeOH showing 30% ellipsoids. Hydrogen atoms are
omitted for clarity.
able. If this reasoning is followed, several of the possible
isomers drawn earlier could be eliminated. To do so, Figure 5
is more suitable. The watch circles are drawn focusing at the
axis S-Ru-S and considering that the NS2C2Ru atoms lie on
one plane. In solution, this is most probably so, due to averaging
of the -CH2 positions which are moving up and down the plane
defined by the NS2Ru atoms. In the solid state, however, the
structures would slightly differ from those because the -CH2
groups would be quenched to get the lowest energy conformers.
If one views the molecule through the axis S-Ru-S, the
substituents on S are at 120° intervals, while these are at 90°
on Ru. Steric repulsions between both S-substituents are
considered negligible, while those between S-R and L are
considered responsible for the type of isomer produced. Then
the cis-meso-Z isomer, where L interacts with both S-R
substituents in a dihedral angle of 30°, will be most unfavorable.
conclude that the influence of the S-substituent was not the
dominant factor affecting the CHaHb 1H NMR chemical shifts.
The geometrical disposition of the chloride ions is the
determining factor in the CHaHb 1H NMR chemical shifts
difference. When both chloride ions are trans to each other,
their influence on each CHaHb is comparable, producing small
∆δ(HaHb) values.23 On the contrary when the relative chloride
disposition is cis, the CHaHb chemical shifts are affected
unevenly, producing large ∆δ(HaHb) values.
This permits us to conclude that the larger ∆δ(HaHb) values
correspond to the cis complex and the lower ∆δ(HaHb) values
correspond to the trans complex. Table 3 provides a list of the
∆δ(HaHb) values found, along with the ratio of both isomers in
solution.
Obviously, the different natures of the S-substituents will
induce variation on the ratios of the cis Vs the trans substituents,
but in general, the steric repulsive effect described earlier seems
to afford a general understanding of the possible isomers to be
expected in these NS2 derivatives.
Structural work was necessary to support this discussion.
Crystals structures of each of the three types of isomers were
produced.
A second 30° interaction is found in cis-dl which provided
the basis for this discussion. On the other hand, the most
favorable arrangement seems to be provided by the cis-meso-
E, where a repulsive dihedral angle of 150° is proposed. The
two trans isomers display repulsive dihedral angles of 60°; thus,
both should have similar steric repulsions and both should, in
principle, exist. According to this reasoning, if three species
are found in the mixture, those should be, in principle,
cis-meso-E and both trans species. Besides, if that was the only
reason, the cis isomer should be produced in larger quantities.
Crystal Structure Description. Attempts to grow crystals
were made in reactions where LX or the ancillary ligands were
different, in the hope of finding distinct isomers. Crystals where
obtained in the reactions leading to [RuCl2(L1)(DMSO)] (Figure
6), [RuCl2(L5)(PPh3)] (Figure 7), and [RuCl2(L6)(PPh3)] (Figure
8). The studied compounds revealed three isomers which
surprisingly corresponded to the three distinct isomers proposed
in the former discussion. The crystals corresponded to trans-
As indicated in the experimental section, for NS2(S-aryl)
complexes a ∆δ(HaHb) close to 1.1 ppm is found in one isomer
while the second isomer has a ∆δ(HaHb) value close to 0.1 ppm.
The complex [RuCl2(L8)L′] (L8 ) NS2(S-ethyl)) was syn-
thesized with the aim of discerning the S-aryl Vs S-alkyl
influence on the δ(Ha) and δ(Hb) values. In this complex, two
isomers were also found, and the ∆δ(HaHb) values were
comparable to those described earlier. One ∆δ(HaHb) was
smaller, 0.9 ppm, while the second one was slightly higher, 0.3
ppm, as compared to the S-aryl compounds. That permitted to
dl-[RuCl2(L1)(DMSO)]‚0.5MeOH,
cis-[RuCl2(L5)(PPh3)]‚
CH2Cl2, and trans-meso-[RuCl2(L6)(PPh3)]‚1.5MeOH. In each
compound the metal assumes a distorted octahedral coordination
(23) Gal, M.; Lobo-Recio, M. A.; Marzin, C.; Seghrouchi, S.; Tarrago, G.
Inorg. Chem. 1994, 33, 4054.

Ru(II) Complexes with NS2 Ligands
Inorganic Chemistry, Vol. 37, No. 4, 1998 707
opposite sides of the NS2Ru plane, while in cis-
[RuCl2(L5)(PPh3)]‚CH2Cl2 and trans-meso-[RuCl2(L6)-
(PPh3)]‚1.5MeOH the rings occupy the same side of the plane.
In the trans-dl-complex each methylene carbon is on the
opposite side of the plane as is the neighboring phenyl group.
In the trans-meso and cis complexes C(1) and C(7) atoms are
on opposite sides of the RuS2N plane, but the C(13) and C(14)
atoms lie on the same side of the plane. These differences can
be clearly seen from the torsion angle values listed in Table 2,
e.g. for N-Ru-S(1)-C(1) and N-Ru-S(2)-C(14) angle
values near 85° (gauche conformation) are obtained when the
methylene carbon and its neighboring phenyl group lie on
different sides of the NS2Ru plane, while the values are ca.
-136° (trans conformation) when the methylene carbon and
its neighboring phenyl group lie on the same side of the NS2Ru
plane. The structure with all-trans conformation was not found.
Figure 7. ORTEP plot of complex unit of cis-[RuCl2(L5)(PPh3)]‚
CH2Cl2 showing 30% ellipsoids. The phenyl groups of PPh3 and
hydrogen atoms are omitted for clarity.
Conclusions
The steric repulsive effect described in this report appears as
the main one responsible for the synthesis of trans-dl, trans-
meso, and cis-meso-E species and not cis-dl or cis-meso-E
isomers. It appears that the nature of the ancillary ligands or
the S-substituent does not determine the kind of isomer
produced.
The geometrical disposition of the chloride ions but not the
S-substituent is the determining factor on the CHaHb 1H NMR
chemical shifts. The larger ∆δ(HaHb) values close to 1 ppm
correspond to the cis complex. Values close to ∆δ(HaHb) )
0.1 ppm are found for the trans isomer.
Although a rearrangement of ligand L1 in the complexation
reaction with [RuCl2(PPh3)3] or [RuCl2(DMSO)4] to an anionic
one could be expected, as it occurred with L1 and [Ru-
(DMSO)6][(BF4)]2, this has not taken place. This rearrangement
was not necessary for [RuCl2(PPh3)3] or [RuCl2(DMSO)4]
probably because anionic coordinating ligands were already
present.
Figure 8. ORTEP plot of complex unit of trans-meso-[RuCl2(L6)-
(PPh3)]‚1.5MeOH showing 30% ellipsoids. The phenyl groups of PPh3
and hydrogen atoms are omitted for clarity.
sphere and the nonaltered ligand LX coordinates tridentately
via the two S atoms and the N atom of pyridine ring to Ru(II).
The remaining three coordination positions are occupied by two
chloride ions and the S atom of DMSO or P atom of PPh3. In
addition to the isomerism and differences in the coordination
spheres, the most interesting point about the structures is the
distinct conformation of the LX ligands.
The pyridine ring and the plane through the atoms Ru, S(1),
S(2), and N are not parallel in any of the three complexes. The
pyridine ring is rotated with respect to the two “substituent arms”
so that C(7) and C(13) are on the opposite sides of the NS2Ru
plane deviating from it by (0.66-0.91 Å. In trans-dl-[RuCl2-
(L1)(DMSO)]‚0.5MeOH the phenyl rings are oriented toward
Acknowledgment. This work was supported by the Projects
MAT93-1334-CE and MAT94-1414-CE. P.A. acknowledges the
award of Grant FIAP-QF95/8.807.
Supporting Information Available: Tables listing crystallographic
data, atomic positional and thermal displacement parameters, and bond
distances and angles for trans-dl-[RuCl2(L1)(DMSO)]‚0.5MeOH, cis-
[RuCL2(L5)(PPh3)]‚CH2Cl2, and trans-meso-[RuCl2(L6)(PPh3)]‚1.5MeOH
(29 pages). Ordering information is given on any current masthead
page.
IC970829N