Redox-active metallodithiolene groups separated by insulating tetraphosphinobenzene spacers

Arumugam, K., Selvachandran, M., Obanda, A., Shaw, M. C., Chandrasekaran, P., Caston Good, S. L., Mague, J. T., Sproules, S. and Donahue, J. P. (2018) Redox-active metallodithiolene groups separated by insulating tetraphosphinobenzene spacers. Inorganic Chemistry, 57(7), pp. 4023-4038. (doi: 10.1021/acs.inorgchem.8b00201) (PMID:29533607)

Abstract

Compounds of the type [(S2C2R2)M(μ-tpbz)M(S2C2R2)] (R = CN, Me, Ph, p-anisyl; M = Ni, Pd, Pt; tpbz = 1,2,4,5-tetrakis(diphenylphosphino)benzene) have been prepared by transmetalation with [(S2C2R2)SnR′2] reagents, by direct displacement of dithiolene ligand from [M(S2C2R2)2] with 0.5 equiv of tpbz, or by salt metathesis using Na2[S2C2(CN)2] in conjunction with X2M(μ-tpbz)MX2 (X = halide). X-ray crystallography reveals a range of topologies (undulating, chair, bowed) for the (S2C2)M(P2C6P2)M(S2C2) core. The [(S2C2R2)M(μ-tpbz)M(S2C2R2)] (R = Me, Ph, p-anisyl) compounds support reversible or quasireversible oxidations corresponding to concurrent oxidation of the dithiolene terminal ligands from ene-1,2-dithiolates to radical monoanions, forming [(−S•SC2R2)M(μ-tpbz)M(−S•SC2R2)]2+. The R = Ph and p-anisyl compounds support a second, reversible oxidation of the dithiolene ligands to their α-dithione form. In contrast, [(S2C2(CN)2)Ni(tpbz)Ni(S2C2(CN)2)] sustains only reversible, metal-centered reductions. Spectroscopic examination of [(−S•SC2(p-anisyl)2)Ni(μ-tpbz)Ni(−S•SC2(p-anisyl)2)]2+ by EPR reveals a near degenerate singlet–triplet ground state, with spectral simulation revealing a remarkably small dipolar coupling constant of 18 × 10–4 cm–1 that is representative of an interspin distance of 11.3 Å. This weak interaction is mediated by the rigid tpbz ligand, whose capacity to electronically insulate is an essential quality in the development of molecular-based spintronic devices.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Sproules, Dr Stephen
• Authors: Arumugam, K., Selvachandran, M., Obanda, A., Shaw, M. C., Chandrasekaran, P., Caston Good, S. L., Mague, J. T., Sproules, S., and Donahue, J. P.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Inorganic Chemistry
• Publisher: American Chemical Society
• ISSN: 0020-1669
• ISSN (Online): 1520-510X
• Published Online: 13 March 2018
• Copyright Holders: Copyright © 2018 American Chemical Society
• First Published: First pubished in Inorganic Chemistry 57(7):4023-4038
• Publisher Policy: Reproduced in accordance with the publisher copyright policy