In:
Dalton Transactions, Royal Society of Chemistry (RSC), Vol. 50, No. 47 ( 2021), p. 17653-17664
Abstract:
The article reported on the diastereomeric dinuclear mixed-valent complexes [(acac) 2 Ru( iii )(μ-O)(μ-Pz R )Ru( iv )(acac) 2 ] (R = H, Me, meso : ΔΛ, 1a–1c; rac : ΔΔ/ΛΛ, 2a–2c) and rac -[(acac) 2 Ru( iii )(μ-O)(μ-Iz)Ru( iv )(acac) 2 ], (2d) (HPz = pyrazole, HIz = indazole, acac = acetylacetonate). Moreover, the diruthenium( ii , ii ) complexes [(HPz) 3 Ru( ii )(μ-O)(μ-Pz) 2 Ru( ii )(HPz) 3 ] (3a) and [(HIz) 3 Ru( ii )(μ-O)(μ-Iz) 2 Ru( ii )(HIz) 3 ] (3d) were presented. The analogous form of 3a, i.e. , [(HPz) 2 (Pz)Ru( iii )(μ-O)(μ-Pz) 2 Ru( iii )(Pz)(HPz) 2 ], was previously reported. Single crystal X-ray structures of 1a–1c/2a–2d and representative 3a showed their molecular forms, including the diastereomeric nature of the former. The Ru–O–Ru angle decreased appreciably on switching from doubly bridged 1 and 2 (128–135°) to triply bridged 3a (114°). Both series of complexes displayed rhombic symmetry in their EPR spectra, with g 1 and g 2 being very similar for 1a–1c with an almost axial look. The mixed-valence complex with a Ru( iii )Ru( iv ) ( S = 1/2) state of 1 and 2 would lead to iso-valence complexes of Ru( iii )Ru( iii ) and Ru( iv )Ru( iv ) with an EPR inactive state by one electron redox reaction. On the other hand, metal based {Ru( ii )Ru( ii )/Ru( ii )Ru( iii ), 3a/3a + } and terminal ligand (HPz/HPz − , 3a/3a − ) based redox processes displayed anisotropic and free radical EPR, respectively. An IVCT (intervalence charge transfer) band was found for the delocalised mixed valent 1 and 2 {Ru( iii )Ru( iv )} or 3a + {Ru( ii )Ru( iii )} in the NIR region. The intense metal-to-ligand charge transfer (MLCT) transitions of 1–3 in the visible region varied systematically as a function of the metal oxidation state.
Type of Medium:
Online Resource
ISSN:
1477-9226
,
1477-9234
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2021
detail.hit.zdb_id:
1472887-4
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