Heterovalent, Homometallic Rings: Synthesis, Optical, and EPR Studies of {TiIV 7TiIII} Complexes
- 1Department of Chemistry and Photon Science Institute The University of Manchester Manchester England
Abstract
We report a new class of heterovalent, homometallic ring complexes, with {TiIV 7TiIII} cores: [py‐CH2NH2Et][Ti7TiO8(O2CR)16] (R = tBu and cyclopropyl). The compounds are made from [Ti(OiPr)4] reacted with carboxylic acid and py‐CH2NHEt. We also show that {TiIV 7TiIII} rings can be generated by photoreduction of {TiIV 8} precursors in the presence of a suitable sacrificial electron donor, of relevance to photocatalysts. UV–vis/NIR spectroscopy of the {TiIV 7TiIII} rings reveal Robin and Day Class II mixed‐valent behavior at room temperature, while EPR spectroscopy is consistent with a localized 3d1 (s = 1/2) configuration, with C2 local symmetry, at low temperatures. We compare the EPR behavior of these new rings with the isostructural heterometallic {CrIII 7NiII} rings [py‐CH2NH2Et][Cr7NiF8(O2CR)16], which also have s = ½ ground states, due to strong intramolecular antiferromagnetic exchange interactions. We demonstrate that the electron spin lattice relaxation time constants (T 1) for {TiIV 7TiIII} are over two orders of magnitude longer at low temperatures than for the {Cr7Ni} equivalents, and that phase memory time constants (T m) are maintained to much higher temperatures.
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BibTeX
@article{lockyer2026heterovalent,
title = {{Heterovalent, Homometallic Rings: Synthesis, Optical, and EPR Studies of TiIV 7TiIII Complexes}},
author = {Selena J. Lockyer and Lubomir Loci and Yingzhao Ma and Matthew P. Stevens and Grigore A. Timco and George F. S. Whitehead and Richard E. P. Winpenny and Alice M. Bowen and Eric J. L. McInnes},
journal = {Chemistry (Weinheim an Der Bergstrasse, Germany)},
year = {2026},
month = jul,
doi = {10.1002/chem.71451},
url = {https://doi.org/10.1002/chem.71451},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Heterovalent, Homometallic Rings: Synthesis, Optical, and EPR Studies of {TiIV 7TiIII} Complexes
AU - Selena J. Lockyer
AU - Lubomir Loci
AU - Yingzhao Ma
AU - Matthew P. Stevens
AU - Grigore A. Timco
AU - George F. S. Whitehead
AU - Richard E. P. Winpenny
AU - Alice M. Bowen
AU - Eric J. L. McInnes
PY - 2026
DA - 2026/07/18
JO - Chemistry (Weinheim an Der Bergstrasse, Germany)
DO - 10.1002/chem.71451
UR - https://doi.org/10.1002/chem.71451
AB - We report a new class of heterovalent, homometallic ring complexes, with {TiIV 7TiIII} cores: [py‐CH2NH2Et][Ti7TiO8(O2CR)16] (R = tBu and cyclopropyl). The compounds are made from [Ti(OiPr)4] reacted with carboxylic acid and py‐CH2NHEt. We also show that {TiIV 7TiIII} rings can be generated by photoreduction of {TiIV 8} precursors in the presence of a suitable sacrificial electron donor, of relevance to photocatalysts. UV–vis/NIR spectroscopy of the {TiIV 7TiIII} rings reveal Robin and Day Class II mixed‐valent behavior at room temperature, while EPR spectroscopy is consistent with a localized 3d1 (s = 1/2) configuration, with C2 local symmetry, at low temperatures. We compare the EPR behavior of these new rings with the isostructural heterometallic {CrIII 7NiII} rings [py‐CH2NH2Et][Cr7NiF8(O2CR)16], which also have s = ½ ground states, due to strong intramolecular antiferromagnetic exchange interactions. We demonstrate that the electron spin lattice relaxation time constants (T 1) for {TiIV 7TiIII} are over two orders of magnitude longer at low temperatures than for the {Cr7Ni} equivalents, and that phase memory time constants (T m) are maintained to much higher temperatures.
SN - 0947-6539
SN - 1521-3765
ER -