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

1995; Royal Society of Chemistry; Issue: 10 Linguagem: Inglês

10.1039/dt9950001653

2050-5671

Mario Calligaris, Paolo Faleschini, Flavia Todone, Enzo Alessio, Silvano Geremia,

Organometallic Complex Synthesis and Catalysis

Solid and circular cone angles and ligand profiles have been calculated for some sulfoxides, showing that S-bonded ligands are markedly bulkier than O-bonded ligands. An application of the cone angles to complexes of RuII and RuIII showed that the bonding mode of sulfoxides appears to be the result of a balance between electronic and steric effects. The complex mer-[RuCl3(dpso)3](dpso = Ph2SO) has been synthesized and structurally characterized: triclinic, space group P, Z= 2 with a= 10.315(3), b= 13.093(4), c= 15.692(5)Å, α= 102.98(2), β= 106.79(1), γ= 102.17(2)°. Two of the three sulfoxides are O- and one is S-bonded. One dpso-O is trans to dpso-S, while the other is trans to Cl. The co-ordination bond distances are consistent with the trans-influence order O < Cl < S. Strain-energy and conformational-entropy terms of three isomers of mer-[RuCl3(dpso)3] have been evaluated through molecular mechanics calculations. The energy difference of 7.6 kcal mol–1 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.