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Feb 15, 1990 - Chloride-Dimethyl Sulfoxide-Ruthenium (III) Complexes. Enzo Alessio,* Gabriele Balducci, Mario Calligaris, Giacomo Costa, Wahib M. Atti...
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Inorg. Chem. 1991, 30, 609-618

Contribution from the Dipartimento di Scienze Chimiche, Universiti di Trieste, 34100 Trieste, Italy

Synthesis, Molecular Structure, and Chemical Behavior of Hydrogen trans -Bis(dimethyl sulfoxide)tetrachlororuthenate(111) and mer-Trichlorotris(dimethy1sulfoxide)ruthenium(III): The First Fully Characterized Chloride-Dimethyl Sulfoxide-Ruthenium( 111) Complexes Enzo Alessio,* Gabriele Balducci, Mario Calligaris, Giacomo Costa, Wahib M. and Giovanni Mestroni

Attia,?

Received February 1.5, I990 The synthesis, molecular structure and chemical behavior of two chloride4imethyl sulfoxide-ruthenium(II1) derivatives, namely ~ Care I , reported. They represent the first examples of fully [(DMSO),H] [ t r a n ~ - R u ( D M S 0 ) ~ C(1) l ~ ]and ~ ~ ~ - R U ( D M S O )(2), characterized halogen-dimethyl sulfoxide-ruthenium(ll1) complexes. Further relevance in their synthesis comes from the known mtitumor properties of isostructural Ru(ll1) complexes with heterocyclic nitrogen ligands and of halogen-dimethyl sulfoxideruthcnium(l1) complexes as well. The crystal structures of 1 and 2 have been determined by three-dimensional X-ray analyses. Crystal data are as follows: [(DMSO),H] [trans-R~(DMSO)~Cl,l, monoclinic, space group P2/n, a = 9.273 ( I ) A, b = 16.509 (3) A, c = 14.023 (3) A, 0 = 100.79 (2)O, Z = 4, R = 0.041; for mer-Ru(DMS0)3C13, monoclinic, space group P 2 , / c , a = 10.105 (2) A, b = 13.832 (3) A, c = 1 I .I 15 (2) A, 0 = 94.39 ( 2 ) O , Z = 4, R = 0.028. In 1 there are two crystallographically independent [ Ru(DMSO),CI,]- anions lying on crystallographic 2-fold axes, passing through Ru and two trans C1 atoms, so that the other two CI atoms and the two S-bonded DMSO molecules are also trans to each other. Cations are provided by protonated DMSO molecules, [Me2S0...H...0SMe2]+ . In 2 the three chlorine atoms are in the mer configuration, and the two trans DMSO molecules arc S-bondcd to Ru, while the third one is 0-bonded. Both complexes are intermediates in the synthesis of c ~ ~ - R u C I , ( D M S O ) ~ from hydrated RuC13. Cyclic voltammetric evidence shows that, in dimethyl sulfoxide and dichloromethane solution, 2 is in cquilibrium with an isomer that very likely differs in the coordination mode of one DMSO (S- to 0-bonded isomerization). The chcmical behavior of 1 and 2 in aqueous solution has been studied at low pH ( 3a(n data/param ratio Rb RwC

GOFd

2

C8H&I,O&Ru C~HI~CI,O&RU 556.4 441.8 monoclinic monoclinic P2/n P2,lC 9.273 (1) 10.105 (2) 16.509 (3) 13.832 (3) 14.023 (3) 11.115 (2) 100.79 (2) 94.39 (2) 2108.8 (6) 1549.0 (5) 4 4 1.75 1.90 0.710 69 (graphite-monochromated Mo Ka) 14.3 19.0 w-2e w-2e 2.5-30 2.5-30 3 3 4052 3919 21.0 4. I 4.0 1.94

27.0 2.8 4.1 1.74

"Measured after each hour. * R = EllFol - lFJ/ElF0l. c R , = [Cw(lFol

- lFc1)2/~1F012]1/2; w = I . dGOF= [Ew(lFoI - IFc1)2/(m- n)]'I2;m = no. of observations: n = no. of variables.

mer-RuC13(DMSO)3 was dissolved in 12 mL of methanol by vigorously stirring the mixture for IO min at room temperature. After this period the product rapidly precipitated from the solution as a yellow solid, which was filtered off, washed with diethyl ether, and vacuum-dried (yield (M, 67%). Mp: I50 OC. Anal. Calcd for RuCI~(DMSO)~(CH,OH) 395.73): C. 15.2; H, 4.07; CI, 26.87: S, 16.20. Found: C, 15.3; H,3.92: CI, 26.30; S, 16.38. Tetraethvlammonium hc-Trichlorotris(dimethv1sulfoxidehuthenate(11) ([NEt;Ifsc-RuCl3(DMSO)3]). A 0.5-g amount of cis-RuCI,(DMSO), (=I mmol) was dissolved in 20 mL of a 1:l mixture of CH2CI2 and CH,OH and 400 mg of Et4NCI (2 mmol) added. The pale yellow solution was refluxed for 15 min and then vacuum-evaporated to I O mL. Bright yellow crystals of the product separated from the solution after some hours at room temperature and were filtered off, washed with acetone, and vacuum-dried (yield 70%). Anal. Calcd for [NEt4][RuCI,(DMSO)p] ( M , 572.07): C, 29.4; H, 6.69; N, 2.44; CI, 18.59; S, 16.81. Found: C, 29.2; H, 6.73; N , 2.40; CI, 18.48; S, 16.90. Crystallographic Study. Crystals of 1 were grown directly from the reaction mixture (procedure a). Crystals of 2 were obtained upon recrystallization of the crude product from dichloromethane/diethyl ether mixtures. Unit cell parameters of both compounds were obtained by least-squares methods from the setting angles of 25 accurately centered reflections on a Enraf-Nonius CAD4 diffractometer. A summary of the crystal data and data collection and refinement is given in Table 1. Intensities were corrected for Lorentz-polarization factors, and an empirical absorption correction was also applied, by using the $-scan data of three close-to-axial reflections. The structures of 1 and 2 were solved by the heavy-atom method through Patterson and Fourier syntheses. All hydrogen atoms were included at calculated positions, except the H atom bridging 0 3 and 0 4 in 1. which was located on a final difference Fourier map (03-H25 = 0.87 A; 0 3 - 0 4 = 2.423 A; 03-H25-04 = 164O). Hydrogen atoms were held fixed during refinement with isotropic B factors = 1.3B, of thc carbon atoms to which they are bonded. The final full-matrix least-squares refinement, with anisotropic temperature factors for all non-hydrogen atoms, converged to R = 0.041 for 1 (based on 4052 reflections) and to 0.028 for 2 (based on 3919 reflections). Neutral atomic scattering factors and anomalous dispersion terms were taken from the l i t e r a t ~ r e . ~ 'All calculations were performed by using the Enraf-Nonius SDP programs34on a PDP 1 1 /44 computer. The final coordinates of non-hydrogen atoms are listed in Tables I I and 111 for 1 and 2, respectively. Bond lengths and angles are given in Tables IV and V (1) and in Table VI (2). The labeling schemes are shown in Figures 1 and 2. For 1 the labeling of the second molecule is obtained from that of Figure 1 by increasing the identification number by 1 for Ru, S, and 0 labels, 2 for C, and 3 for the CI labels. ~~

(33) International Tablesfor X-ray Crystallography; Kyncch: Birmingham, England, 1974; Vol. IV. (34) EnrafNonius SDP Package; B. A. Frenz & Associates, Inc.. College Station, TX 77840 Enraf-Nonius, Delft, Holland.

Table 11. Positional Parameters for Non-Hydrogen Atoms and Their Estimated Standard Deviations for 1 atom X Y Z B,' A2 Rul 0.250 0.58283 (3) 0.250 1.997 (8) Ru2 0.750 -0.00617 (3j 0.250 1.897 (8) 0.7253 ( 1 ) CI I 0.250 0.250 5.15 (5) c12 0.4413 ( I ) 0.250 0.250 3.83 (4) 0.5838 ( I ) C13 0.2185 (1) 0.07950 (9) 4.03 (3) C14 0.750 0.1356 ( I ) 0.250 8.4 ( I ) -0.1458 ( I ) 11.4 ( I ) 0.750 C15 0.250 9.00 (7) 0.7110 (2) -0.0031 (2) C16 0.0820 ( I ) SI 0.58087 (8) 0.26683 (8) 2.62 (2) 0.5066 ( 1 ) s2 0.4940 ( 1 ) -0.00614 (7) 0.23859 (8) 2.30 (2) 0.31 169 (9) s3 0.0979 ( I ) 3.78 (3) 0.5352 (2) 0.0972 ( I ) 0.19722 (9) s4 0.0815 (2) 3.64 (3) 01 0.1779 (3) 0.5660 (4) 0.5723 (3) 4.67 (9) 02 0.3299 (3) 0.4380 (4) -0.0011 (3) 3.97 (8) 4.19 (9) 03 0.2731 (2) 0.1541 (3) 0.4269 (4) 6.1 ( I ) 04 0.2511 (3) 0.0536 (3) 0.1876 (5) c1 0.5879 (6) 0.5041 (4) 0.3472 (5) 5.6 ( 1 ) c2 5.1 (1) 0.6666 (4) 0.3290 ( 5 ) 0.5917 (6) 0.1621 (4) c3 3.3 ( 1 ) 0.0725 (3) 0.4096 ( 5 ) 0.4099 (6) -0.0904 (3) 4.0 ( 1 ) 0.1713 ( 5 ) c4 0.2500 (4) -0.0054 (5) c5 5.6 (2) 0.5323 (7) 0.0428 (4) 0.3989 (4) 4.7 ( I ) 0.4462 (7) C6 -0.0575 (8) 7.7 (2) 0.1097 (6) 0.2657 (6) c7 -0.0018 (6) 6.7 (2) 0.1389 ( 5 ) C8 -0.003 ( I ) " B values for anisotropically refined atoms are given in the form of the isotropic equivalent displacement parameter defined as (4/3) [a2B( 1 , l ) + b2B(2,2) + c2B(3,3) + ab(cos y)B(1,2) + ac(cos P)B(1,3) + bc(cos a)B(2,3)]. Table 111. Positional Parameters for Non-Hydrogen Atoms and Their Estimated Standard Deviations for 2 atom X Y z B.' A2 Ru 0.77705 (3) 0.00819 (2) 0.72375 (3) 1.743 (4) CI 1 0.01294 (8) 0.7290 (1) 2.89 (2) 1.00699 (9) c12 0.09489 (8) 0.9051 (1) 0.7757 (1) 3.06 (2) 0.7491 ( 1 ) -0.07838 (8) 0.54212 (9) 2.96 (2) C13 SI 0.00581 (9) 0.83301 (9) 2.65 (2) 0.4954 ( I ) -0.13593 (7) 0.8326 ( I ) s2 0.7892 ( I ) 2.39 (2) 0.7683 (1) 0.15300 (8) 0.6127 ( I ) s3 2.50 (2) 01 0.5711 (3) 0.7175 (3) 0.0105 (2) 2.55 (5) 02 -0.1737 (3) 3.87 (7) 0.6602 (3) 0.8675 (4) 03 0.8021 (4) 0.6782 (4) 0.2435 (2) 4.12 (8) c1 0.3573 (5) -0.0677 (5) 0.7872 (6) 5.2 ( I ) c2 5.6 ( I ) 0.4163 (7) 0.8337 (6) 0.1200 (5) c3 -0.1279 (4) 4.0 ( I ) 0.9026 (5) 0.9637 (5) 3.8 ( I ) c4 0.8699 (5) 0.7552 ( 5 ) -0.2290 (4) 0.1671 (4) 0.5330 (5) 4.0 ( I ) c5 0.6083 (5) 0.1452 (4) C6 3.33 (9) 0.4902 (4) 0.8718 (5) " B values for anisotropically refined atoms are given in the form of the isotropic equivalent displacement parameter defined as (4/3)[a2B( 1 , l ) + b2B(2,2) + cZB(3,3) + ab(cos y)B(1,2) + ac(cos P)B(1,3) + bc(cos a)B(t,3)].

(A) for

Rul-CII Rul-CI2 Rul-CI3 Rul-SI SI-01 s1-CI SI-C2

1 (a) Ru Anions 2.352 ( I ) Ru2-CI4 Ru2-CI5 2.337 (1) 2.3539 (9) Ru2-CI6 2.3474 (8) Ru2-S2 1.461 (3) s2-02 1.769 (5) S2-C3 1.768 (5) S2-C4

S3-03 s3-c5 S3-C6 S4-04

(b) [(DMSO),H] Cation 1.528 (4) s4-c7 1.766 (6) S4-C8 1.764 (5) 03*.*04 1.536 (3)

Table IV. Bond Distances

2.341 (2) 2.306 (2) 2.316 ( I ) 2.3492 (7) 1.472 (3) 1.770 (4) 1.777 (4) 1.748 (5) 1.749 (6) 2.423 (5)

'

Results Synthesis and Molecular Structure of 1. [(DMSO),H][ t r a m - R ~ ( D M S 0 ) ~ C(1) l ~ (d5 ] low spin, peff= 1.89 pB) was first isolated f r o m t h e mother liquors in t h e synthesis of cis-RuCI,-

612 Inorganic Chemistry, Vol. 30, No. 4, 1991 Table V. Bond Andes (del21 for la (a) Ru Anions 180 C16-R~2-S2 CII-Rul-CI2 C16-R~2-S2' CII-Rul-CI3 89.60 (3) CII-Rul-SI 90.79 (3) S2-Ru2-S2' C12-Rul-CI3 90.41 (3) Rul-SI-OI 89.21 (3) Rul-SI-Cl CI2-Rul-SI C13-Rul-CI3' 179.18 (6) RuI-SI-C~ C13-Rul-SI 91.89 (3) 01-SI-CI Cl3-R~l-Sl' 88.12 (3) OI-SI-C2 SI-Rul-SI' 178.43 (6) CI-SI-C2 180 Ru2-S2-02 C14-RuZ-CI5 Ru2-S2-C3 C14-Ru2-Clh 88.73 (6) C14-R~2-S2 89.99 ( 2 ) Ru2-S2-C4 02-S2-C3 C15-Ru2-CI6 91.27 (6) CIS-Ru2-SZ 90.01 (2) 02-S2-C4 C16-Ru2-CI6' 177.5 ( I ) c3-s2-c4 03-S3-C5 03-S3-C6 C5-S3-C6 04-S4-C7

Alessio et a].

CI 3'

88.13 (3) 91.87 (3) 180.01 (3) 116.9 ( I ) 112.1 (2) 112.9 (2) 106.9 (2) 107.1 (2) 99.3 (3) 117.3 (2) 1 1 I .6 ( I ) 111.9 ( I ) 107.4 (2) 108.4 (2) 98.8 (2)

(b) [(DMSO),H] Cation 105.8 (3) 04-S4-C8 105.5 (2) C7-S4-C8 03-He - 0 4 100.2 (3) 101.8 (3)

b)

103.2 (3) 101.9 (3) 164

53

"Primed atoms are referred to the nonprimed ones by crystallographic 2-fold axcb.

Table VI. Bond Distances Ru-CII Ru-CI2 Ru-CI~ Ru-S~ Ru-S~ Rh-Ol SI-01 SI-CI CII-Ru-CI2 CII-Ru-CI3 CII-RU-S~ CII-RU-S~ CII-Ru-OI C12-Ru-CI3 CIZ-RU-S~ C12-Ru-S3 C12-Ru-OI CI3-Ru-S2 C13-Ru-S3 CI~-RU-OI S2-Ru-S3 S2-Ru-OI S3-Ru-0 I 01-SI-CI

(A) and Angles (deg) for 2

(a) Distances 2.321 ( I ) SI-C2 S2-02 2.347 ( I ) 2.346 (2) S2-C3 2.330 (2) S2-C4 2.351 ( I ) S3-03 2.077 (3) S3-C5 1.545 (4) S3-C6 1.770 (6)

1.771 (7) 1.484 (4) 1.788 ( 5 ) 1.780 (5) 1.474 (4) 1.793 ( 5 ) 1.782 (5)

(b) Angles 92.02 (5) OI-Sl-C2 95.20 (4) CI-SI42 89.89 (4) Ru-S2-02 89.23 (4) Ru-S2-C3 Ru-SZ-C~ 177.5 ( I ) 172.78 (4) 02-S2-C3 89.71 (4) 02-S2-C4 90.75 (4) C3-S2-C4 87.10 (9) Ru-S3-03 90.47 (4) Ru-S3-C5 89.20 (4) Ru-S3-C6 85.68 (9) 03-S3-C5 179.02 (4) 03-S3-C6 92.48 (9) C5-S3-C6 88.41 (9) Ru-01-SI 102.4 (2)

102.7 (3) 99.6 (4) 115.2 ( I ) 112.0 (2) 112.1 (2) 109.3 (2) 108.4 (2) 98.7 (3) 117.8 (2) 110.4 (2) 110.4 (2) 108.6 (2) 107.5 (2) 100.9 (2) 122.0 (2)

(DMS0),.I9 The yield of the complex could be greatly improved by running the reaction at 100 "C in the presence of small amounts of concentratcd HCI. On the contrary, attempts to isolate the corresponding bromo derivative failed due to the easier reducibility of RuBr, relative to RuCI,; for example, overnight stirring of a solution of hydrated RuBr, in dimethyl sulfoxide (room temperature, under air) yields almost quantitatively trans-RuBr2The main features of the solid-state infrared spectrum of 1 are reported in Table VII. Only one S=O stretching band is observed at 1 I 15 cm-' (S-bonded DMS0).36.37 The existence of a single u(S=O) suggests a trans configuration. A very broad band centered at 725 cm-I can be attributed to the hydrogen-bridged cation [(DMS0)2H]+,as previously reported for a rhodium(lI1) chloride dimethyl sulfoxide c o m p l e ~ The . ~ ~band ~ ~ assignment ~ ~

35) 36) 37) 38)

~~

~~~~~~~

Alessio, E. Ph.D. Dissertation, University of Trieste. Trieste, Italy, 1989. Reynolds, W. L. Prog. Inorg. Chem. 1970, 12, 1. Davies. J. A. Ado. Inorg. Chem. Radiochem. 1981, 24, 1 1 5 . James. B. R.; Morris, R. H.; Einstein, F. W. B.; Willis, A. J . Chem. Soc., Chem. Commun. 1980, 3 1 ,

Figure 1. ORTEP drawing of the [~rans-Ru(DMS0)~Cl,]anion (a) and of the [(DMSO),H]' cation (b) with the atom-labeling scheme.

Figure 2. ORTEP drawing of mer-[RuC13(DMSO),(DMSU)]" with the atom-labeling scheme.

is confirmed by the infrared spectrum of the deuterated complex (Table VII). The structure was definitively determined by a single-crystal X-ray analysis. The crystal structure of complex IN consists of [(DMSO),H]+ cations and trans-[R~(DMSO)~Cl,1anions, held together by van der Waals forces. Two crystallographically independent anions lie on crystallographic 2-fold axes passing through the metal atoms and two trans chlorine atoms, so that for each Ru there are three CI and one DMSO independent ligands. The molecular structures of one of the two anions and of the cation are shown in Figure 1 . Complex 1 is essentially isostructural with the Rh analogue,38 in which, however, the chlorine atoms of one of the two independent anions were too disordered to be located. In fact, also in 1, the four chlorine atoms around Ru2 have rather large thermal (39) James, B. R.; Morris, R. H. Can. J . Chem. 1980, 58, 399. (40) Note: After submission of our manuscript, we became aware of an independent paper, submitted by J. Jaswal, S. J. Retting, and B. R. James, to Can. J . Chem., describing the synthesis and crystal structure of 1. The cell parameters are in excellent agreement with those reported in Table I . The complex was isolated while the authors were trying to reproduce the synthesis ofJac-RuCI,(DMSO), as reported by Pcddar's group in ref 28a.

Inorganic Chemistry, Vola30, No. 4, 1991 613

Chloride-Dimethyl Sulfoxide-Ruthenium( 111) Complexes

Table VII. Vibrational Frequencies (cm-') for the Main Absorption Bands of [(DMS0)2H][tr~ns-Ru(DMS0)~Cl~] ( l ) , mer-[R~Cl~(DMS0)~1 (2). and Their Hexadeuterated Analogues l(DMSO-dh) and 2(DMSO-dh)between 1500 and 200 cm-'

I(DMSO-d,)

1

1397 mb 1296 m 1289 m 1115s

IO21 m 1008 m

1018 s 970 m 916 w

838 s 822 s 772 m

1112s

peaks hidden by cation abs

415 381 345 329

w w

sh s

384 w (1.08) e 340 sh 326 s

freq, cm-' 2 1405 s 1308 s 1287 s 1127 s 1107 s 1017 s 978 m 962 m 912 s 725 m 677 m 496 m 411 m 371 w 342 s, br

2"

2(DMSO-d,)

trans- [ Ru( DMSO),CI,]-

+ Ag+

-

1030 sh 1007 s 944 m 1126 s 1107 s 821 s 764 s

1129 s 1119sh 1018 s 980 m 970 w 918 s, br

910 702 623 472

494 s, br 432 m 409 s

] u(S=O)

(DMSO)

u(S=O) (DMSO)

s

} 4C-S) ~Ru-0) } u(Ru-S)

w (1.03)d w (1.08)

m (1.05)

376 m (1.09) 348 w (1.06) 330 s, br

stretching; 6, deformation;p, rocking. dNumbers in parentheses

In CH2CIzsolution. bsh, shoulder; w, weak; m, medium; s, strong; br, broad. refer to the isotopic ratios. ePeak hidden by Ru-CI stretching.

factors (see Table 11). This explains the shortening of the R u 2 - W and Ru2-CI6 bond distances (Table IV) with respect to the other Ru-CI bond distances, which average 2.346 (8) 8,. This value is practically equal to the values found for trans Ru(ll1)-CI bond distances in 2 (see below). The structure of the protonated dimethyl sulfoxide, [(DMSO),H]+, is equal, within experimental error, to that of the Rh analogue.38 Of interest, in both compounds the structural parameters of the two DMSO molecules are not perfcctly cquivalcnt. The corresponding sodium and potassium salts of 1 could be easily isolated from H,O/ethanol solutions of the complex treated with a slight excess of the corresponding chloride salt. Synthesis and Molecular Structure of 2. When an acetone/ dimethyl sulfoxide ( 1 % ) solution of 1 is treated with 1 equiv of AgBF4, thc ncutral complex RuCI,(DMSO)~(2) (d5 low spin, Merr = 1.87 pB) can be isolated after removal of AgCl (eq 1).

assgnt

Table VIII. Average Structural Parameters (A and deg) for Ru(1I) S- and 0-Bonded DMSO Complexes, [RUX,(DMSO)~]~ (X = CI, Br) X"

Ub

PC

nd

ref

Ru-CI'

2.358 2.278 2.428

0.007 0.014 0.01 1

0.003 0.002 0.002

2 14 12

h h

s-c s-0

1.785 1.479

0.018 0.012

0.002 0.002

50 26

i i

0-S-C C-S-C

105.9 99.0

1.2 1.5

0.1 0.3

46 23

i i

s-c

s-0

1.773 1.539

0.013 0.013

0.003 0.004

20 IO

0-S-C C-S-C

103.1 98.6

1.4 0.9

0.3 0.4

14 7

I I I

Ru-S' Ru-S'

DMSO

+

g

S-Bonded DMSO

0-Bonded DMSO

1 RuC13(DMS0)3 AgCl (1) Weighted mean, x = xiwix{xiwi; w i = l/a:. bStandard deviaThe treatment of 1 with 2 or more equiv of AgBF, yielded only tion, u = [ x i ( x i- x ) * / ( n- I)]'/ . CStandarddeviation of the mean, p the Ru(l1) complex trans-RuC12(DMS0)4. No evidence for the = [(xiwi(xi - x)z/xiwi)/(ndNumber of observations. claimed pentakis- and hexakis(dimethy1 sulfoxide)ruthenium( 111) 'Trans to S. fTrans to C1. gReferences 15 and 19. References 14, derivatives, [RU(DMSO)~CI]CI~ and [ R U ( D M S O ) ~ ] C could I ~ , ~ ~ ~ ~ 15, 17, and 19. 'References 14-17, 19, and 45. 'References 14, 17, be obtaincd. 19, and 45. The solid-state infrared spectrum of 2 (Table V I I ) shows the presence of two S-bonded and one 0-bonded DMSO's. Irrereproduce the synthesis of mer-RuCI,(DMSO)(DMSO), claimed spective of the facial or meridional ligand disposition, the complex in ref 28a. The close similarity between the spectra of the two should have one Ru-O, two Ru-S, and three Ru-CI infrared-active complexes suggests that also the product isolated by Poddar's stretching m ~ d c s . ~ The ' presence of a single v(Ru-S) might group28amight have been actually a DMS complex.40 suggcst a trans disposition of the two DMSO's. The three Ru-CI The molecular structure of 2 is shown in Figure 2. Ruthenium strctching bands expected might be enclosed in the relatively broad has a distorted octahedral coordination with three chlorine atoms band at 341 cm-I. Band a ~ s i g n m e n t ~ *is~confirmed '-~~ by rein a mer configuration. Two DMSO molecules are S-bonded to placement of DMSO with DMSO-d,. As expected, the S=O Ru in trans position, while the third one is 0-bonded, constituting stretching frcqucncies do not shift upon deuteration, while the a isomer different from the Rh(II1) analogue, where the 0-bonded isotopic shifts of u(Ru-0) and v(Ru-S) are close to the expected DMSO is trans to one S-bonded DMSO ligand.44 The Ru-S value of I .05.,' distances (Table VI) are not equivalent, but the average value The spectrum of 2 is considerably different from that reported is close to that of 2.348 (1) 8, found in 1. The S-O bond distance by Sarma ct al. for the complex formulated as mer-RuC1,of the 0-bonded DMSO is markedly longer than those of the (DMSO)(DMS0)2.28a In that report, however, the absence of S-bonded DMSO ligands, just as found in the Ru(I1) derivatives the dcutcratcd analogue makes the band assignments not un(Table VIII), showing a considerable decrease of the double-bond equivocal. Indeed, a recent work by the group of Jamesa describes character of the sulfur-oxygen bond upon coordination to the the structural characterization of a dimethyl sulfide (DMS) metal atom via oxygen. The different electronic situation of the complcx, mer-RuCI3(DMS),, obtained while they were trying to sulfur atom is reflected in the significant narrowing (ca. 5.9') of the 0-S-C bond angles, passing from the S- to the 0-bonded DMSO ligands. This can be attributed to the compression effect (41) Fadeev, Yu.V.;Kukushkin, Yu.N.; Khokhryakov, K. A. Russ. J . Inorg. (I

Cheni. (Engl. Trans/.) 1975, 20, 1519. (42) Price, J. H.; Williamson, A . N.; Schramm, R. F.; Wayland, B. B. Inorg. Chem. 1972, I I , 1280. (43) Barnes, J. R.; Goggin, P. L.;Goodfellow, R. J. J . Chem. Res., Miniprint 1979, 1610.

(44) Sokol, V. 1.; Porai-Koshits, M. A. Koord. Khim. 1975, I , 577. (45) Davies, A. R.; Einstein, F. W. B.; Farrell, N. P.; James, B. R.; McMillan, R. S. Inorg. Chem. 1978, 17, 1965.

Alessio et al.

614 Inorganic Chemistry, Vol. 30, No. 4, 1991

Synthetic Connections between Ruthenium(II1) and Ruthenium(l1) Chloride Dimethyl Sulfoxide Complexes'

Scheme 1.

IX. Redox Potentials (mV vs SCE) for All the Proposed Species in DMSO and H20Solutions comolex DMSO" H,Ob comdex D M S P H,Ob

Table

R u C S . nHzO

,,I C1-

"./ Ru-C1 I L1 I S

\ [DMSO

h. . . . . . . e