Dichlorotetrakis(dimethylsulfoxide)ruthenium(II) explained

Dichlorotetrakis(dimethyl sulfoxide) ruthenium(II) describes coordination compounds with the formula RuCl₂(dmso)₄, where DMSO is dimethylsulfoxide. Both cis and trans isomers are known, but the cis isomer is more common. The cis isomer is a yellow, air-stable solid that is soluble in some organic solvents. These sulfoxide complexes are used in the synthesis of various ruthenium(ii) complexes.^[1] They have also attracted attention as possible anti-cancer drugs.

Structure and synthesis

The cis isomer illustrates linkage isomerism for the DMSO ligand.^[2] One of the two dmso ligands that are cis to both chloride ligands is O-bonded while the other three dmso ligands are S-bonded. In the trans isomer, which is also yellow, all four dmso ligands are S-bonded. The cis isomer is formed thermally, and the trans isomer is obtained by UV-irradiation of the cis isomer.

The complexes were first prepared in 1971 by heating DMSO solutions of ruthenium trichloride under hydrogen atmosphere.^[3] Modern procedures has been developed which avoids hydrogen gas, either using ascorbic acid or refluxing DMSO to reduce the ruthenium.^{[4] [5]}

Potential applications

RuCl₂(dmso)₄ was identified as a potential anticancer agent in the early 1980s.^[6] Continued research^{[7] [8]} has led to the development of several related dmso-containing ruthenium compounds, some of which have undergone early-stage clinical trials.^[9]

Notes and References

1. Alessio . Enzo . 2004-09-01 . Synthesis and Reactivity of Ru-, Os-, Rh-, and Ir-Halide−Sulfoxide Complexes . Chemical Reviews . en . 104 . 9 . 4203–4242 . 10.1021/cr0307291 . 0009-2665.
2. Enzo Alessio . Synthesis and reactivity of Ru-, Os-, Rh-, and Ir-halide-sulfoxide compounds . . 2004 . 104 . 4203–4242 . 10.1021/cr0307291 . 9. 15352790 .
3. B. R. James . E. Ochiai . G.I. Rempel . Inorganic and Nuclear Chemistry Letters. 7 . 781–784 . 1971 . 10.1016/0020-1650(71)80091-0 . Ruthenium (II) halide dimethylsulphoxide complexes from hydrogenation reactions . 8.
4. Book: I. Bratsos . E. Alessio . . 35 . 148–152 . 2010 . Ruthenium(II) Chloro Complexes of dimethylsulfoxide . 10.1002/9780470651568.ch8 .
5. Nagy, E. M. . Pettenuzzo, A. . . 18 . 14464–14472 . 2012 . Ruthenium(II/III)-Based Compounds with Encouraging Antiproliferative Activity against Non-small-Cell Lung Cancer . 45 . 10.1002/chem.201202171. 23012112 .
6. Sava. Gianni. Giraldi. Tullio. Mestroni. Giovanni. Zassinovich. Grazia. Antitumor effects of rhodium(I), iridium(I) and ruthenium(II) complexes in comparison with cis-dichlorodiammino platinum(II) in mice bearing Lewis lung carcinoma. Chemico-Biological Interactions. July 1983. 45. 1. 1–6. 10.1016/0009-2797(83)90037-6. 6683595 .
7. Coluccia. Mauro. Sava. Gianni. Loseto. Francesco. Nassi. Anna. Boccarelli. Angela. Giordano. Domenico. Alessio. Enzo. Mestroni. Giovanni. Anti-leukaemic action of RuCl2(DMSO)4 isomers and prevention of brain involvement on P388 leukaemia and on subline. European Journal of Cancer. January 1993. 29. 13. 1873–1879. 10.1016/0959-8049(93)90541-M. 8260245 .
8. Bratsos, I . Serli, B . Zangranko, E . Katsaros, N . Alessio, E. . Replacement of chlorides with dicarboxylate ligands in anticancer active Ru(II)-DMSO compounds: A new strategy that might lead to improved activity . . 46 . 975–992 . 10.1021/ic0613964 . 2007 . 17257042 . 3.
9. Enzo Alessio. Bentham Science Publisher. Giovanni Mestroni. Bentham Science Publisher. Alberta Bergamo. Bentham Science Publisher. Gianni Sava. Bentham Science Publisher. Ruthenium Antimetastatic Agents. Current Topics in Medicinal Chemistry. 1 November 2004. 4. 15. 1525–1535. 10.2174/1568026043387421. 15579094 .