Homoleptic and heteroleptic complexes of chromium(III) containing 4′-diphenylamino-2,2′:6′,2″-terpyridine ligands

Abstract

Two heteroleptic bis(2,2':6',2''-terpyridine)chromium(III) complexes [Cr(1)(4'-(4-

CrIIIas an alternative to RuIIin metallo-supramolecular chemistry

“…4). 46,84 Beyond [Cr(tpy)Cl 3 ], the structure of which was previously reported ( Fig. 4 top centre), 61,93 we confirm that the three weakly bound THF molecules in CrCl 3 (THF) 3 can be displaced by closely related tridentate ligands 94 to give [Cr(ebzpy) Cl 3 ]•DMF (5, Tables S12-S14 and Fig.…”

“…Creutz-Taube complex, (b) [(tpy)Ru(L)Ru(tpy)] m+ complexes, [69][70][71] (c) [(tpy)Ru II (L)Co III (tpy)] 5+ complexes displaying directional electron transfer, 72,73 (d) [(tpy)Ru II (L)Os II (tpy)] 4+ complexes displaying directional energy transfer. 74,75 six-coordinate bis-terimine 83,84 and ter-bisimine 46,81,82 Cr III complexes. Building on the identification of labile Cr III -O(triflate) bonds and their easy formation from Cr-Cl bonds, we herein propose to extend this procedure for the synthesis of a series of novel back-to-back dinuclear [X 3 Cr III (L)Cr III X 3 ] complexes (Scheme 1, X 3 = Cl 3 or X 3 = tpy), which are reminiscent of the well-known Ru II dyads.…”

“…However, the lack of easy accessible synthetic procedures for the preparation and characterization of pure heteroleptic polynuclear chromium complexes has up to now prevented Cr III polypyridines from being used as active building blocks in (supra)molecular optical devices. Recently, Barker et al, 81 Isaacs et al 82 and Housecroft and Constable et al 46,83,84 tried to find a remedy for this frustrating limitation with the systematic exploration of the stability and lability of mononuclear 59,60 The upward green arrow stands for the lowest-energy spin-allowed absorption transition, while the downward red arrow refers to the lowest-energy phosphorescence.…”

Luminescent polypyridyl heteroleptic CrIII complexes with high quantum yields and long excited state lifetimes

“…5,23 However, the incorporation of these chromophores into optically active supramolecular devices is limited and still underexplored since it requires the preparation of heteroleptic complexes that can act as "building blocks", an issue solved since several decades for Ru(II) chemistry. 24 In this context, the three-step strategy described by Kane-Maguire and co-workers for the synthesis of heteroleptic [Cr(diimine) 3 ] 3+ , 25 further extended by Constable and co-workers for the synthesis of heteroleptic [Cr(triimine) 2 ] 3+ , 26 relies on the lability of the {Cr-OSO 2 CF 3 } bond that is easily generated by the reaction of the {Cr-Cl} moieties with trifluoromethanosulfonic acid (CF 3 SO 3 H). Reaction of the labile intermediate with the additional triimine ligand (L′) generates the corresponding heteroleptic [(L)Cr(L′)] 3+ complex.…”

Tuning peripheral π-stacking motifs in {Cr(tpy)2}3+ domains (tpy=2,2′:6′,2″-terpyridine)

“…Subsequent exchange of the chlorido ligands by the more labile triflate, followed by reaction with a second equivalent of tpy yields the triflate salt of the desired complex [7,8]. Scheme complexes (4'-Phtpy = 4'-phenyl-2,2':6',2''-terpyridine) [11] In conclusion, we demonstrate that the introduction of the naphth-2-yl domain in [Cr (1) …”