Pramanik, Amitava ; Bag, Nilkamal ; Lahiri, Goutam Kumar ; Chakravorty, Animesh (1990) Geometrical isomer preference of RuII and RuIII: chemistry and structure of a RuS4P2 family. Crystal structure of [Ru(PhCH2SCS2)2(PPh3)2] Journal of the Chemical Society, Dalton Transactions (12). pp. 3823-3828. ISSN 1472-7773
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Official URL: http://pubs.rsc.org/en/Content/ArticleLanding/1990...
Related URL: http://dx.doi.org/10.1039/DT9900003823
Abstract
The syntheses of mixed thioxanthate (trithiocarbonate)-phosphine complexes of types cis-[Ru(RSCS2 )2(PPh3)2](1) and trans-[Ru(RSCS2)2 (PPh3)2]PF6(2+) are reported (R = Et, Pri, or PhCH2). These along with trans-[Ru(RSCS2)2(PPh3) 2](2) and cis-[Ru(RSCS2)2(PPh3)2] +(1+) constitute an electrochemically observable redox isomerisation cycle. The formal potentials of the couples (1+)-(1) and (2+)-(2) are ≈ 0.65 and ≈ 0.33 V respectively vs. saturated calomel electrode (s.c.e.). The isomerisation steps are (1+)→(2+)(fast) and (2)→(1)(k≈ 7.0 x 10-2 s-1). The X-ray structure of complex (1; R = PhCH2) has been determined: space group C2/c, a= 18.676(7), b= 10.511(2), c= 24.432(8)Å , and Z = 4. The superior stability of the cis configuration of RuII for complexes (1) arises primarily from the strong back-bonding (cis > trans) within the Ru(PPh3)2 fragment. For RuIII, in which back-bonding is unimportant, the stable geometry is trans owing to favourable steric disposition of the PPh3 molecules. The frozen glass e.s.r. spectra of complexes (2+) have a sizable axial distortion (Δ≈ 8 500 cm-1) with a relatively small rhombic component (V≈ 2 200 cm-1). One of the two predicted transitions (∨ 1≈ 7 500 and ∨2≈ 9 900 cm-1) within the t2g shell is observable (∨1≈ 6 500 cm-1) in the near-i.r. region.
| Item Type: | Article |
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| Source: | Copyright of this article belongs to Royal Society of Chemistry. |
| ID Code: | 88441 |
| Deposited On: | 28 Mar 2012 08:57 |
| Last Modified: | 13 Jul 2012 13:43 |
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