Steric properties of sulfoxide ligands. Synthesis and crystal structure of mer-[RuCl3(Ph2So)3]

Abstract

Solid and circular cone angles and ligand profiles have been calculated for some sulfoxides, showing that S-bonded ligands are markedly bulkier than 0-bonded ligands. An application of the cone angles to complexes of Ru" and Ruii' showed that the bonding mode of sulfoxides appears to be the result of a balance between electronic and steric effects. The complex mer-[RuCl,(dpso),] (dpso = Ph,SO) has been synthesized and structurally characterized: triclinic, space group P i , Z = 2 with a = 10.315(3), b = 13.093(4), c = 15.692(5) A, a = 102.98(2), p = 106.79(1), y = 102.17(2)". TWO of the three sulfoxides are 0and one is S-bonded. One dpso-0 is trans to dpso-S, while the other is trans to CI. The co-ordination bond distances are consistent with the trans-influence order 0 < CI < S. Strain-energy and conformational-entropy terms of three isomers of mer-[RuCl,(dpso),] have been evaluated through molecular mechanics calculations. The energy difference of 7.6 kcal mol-' between the characterized complex and the linkage isomer with two trans dpso-S ligands indicates that the isomer isolated is probably favoured thermodynamically and suggests that the interligand steric interactions play an important role in the isomer stability.

The Pivotal Role of Ru‐dmso Compounds in the Discovery of Well‐Behaved Precursors

“…For this reason, it stabilizes the +2 oxidation state and Ru II complexes with at least one dmso‐S are typically air‐stable also in solution. As will become clear from the subsequent sections, the binding mode of dmso on Ru II and Ru III depends on the net charge of the complex, on the nature of the supporting ligands (in particular of the one in trans position), and on steric factors: dmso‐S, with a Tolman's cone angle θ = 112°, is more sterically demanding than dmso‐O, θ = 100° , . Both binding modes are easily distinguishable, besides from the X‐ray structure, through IR and NMR spectroscopy .…”

Synthesis and Reactivity of Ru-, Os-, Rh-, and Ir-Halide−Sulfoxide Complexes

“…NMR spectroscopy established that in CDCl 3 solution complex 42 equilibrates with an all S-bonded minor isomer formulated as mer-RhCl 3 (dmso-S) 3 (44), which was never isolated (Scheme 50). 382,383,389 As found for the anionic isomers 40 and 41, a significant increase of the Rh-S bond length was observed in the neutral trans isomer 43 (average 2.311(6) Å), compared to the cis isomer 42 (average 2.243(16) Å).…”

“…To the best of our knowledge, there is only one welldocumented example, in which both isomers have been characterized both spectroscopically and structurally by X-ray: cis,fac-OsCl 2 (dmso-S) 3 (dmso-O) (38) vs cis-OsCl 2 (dmso-S) 4 (39) (Scheme 54). 369,370,372 Other examples were documented in solution, but only one of the isomers (at best) could be isolated and structurally characterized in the solid state (Scheme 54): mer,cis-RuCl 3 (dmso-O) 2 (NO) (22) vs mer,cis-RuCl 3 -(dmso-O)(dmso-S)(NO) (22b), 84 cis,cis,cis-RuCl 2 (dmso-S) 2 (dmso-O)(CO) (30) vs cis,mer-RuCl 2 (dmso-S) 3 (CO) (31), 337 mer,cis-RhCl 3 (dmso-S) 2 (dmso-O) (42) and mer, trans-RhCl 3 (dmso-S) 2 (dmso-O) (43) vs mer-RhCl 3 -(dmso-S) 3 (44), 382,383,389 (48). 382 Actually, the case of mer,cis-RhCl 3 (dmso-S) 2 (dmso-O) (42) vs mer,trans-RhCl 3 (dmso-S) 2 (dmso-O) (43) is particular, in the sense that it may be seen as involving either a double linkage isomerization or a geometrical isomerization.…”

A Molecular Mechanics Force Field for Alkylcobaloximes, a Model of Vitamin B12 Coenzyme – Implications of Steric and Electronic Factors in the Co–C Bond Cleavage

“…Cone angles for the axial ligands were calculated according to the ImmirziЈs algorithm, [33] as modified in ref. [21] , using the atom coordinates of the 52 energy minimized structures. The van der Waals radii used for the ligand atoms were those given by Bondi, [34] assigning a zero value to the metal-coordinated atoms.…”