title: Modulation of electronic couplings within Ru2-polyyne frameworks.
abstract: Dimers of [Ru(2)(Xap)(4)] bridged by 1,3,5-hexatriyn-diyl (Xap are 2-anilinopyridinate and its aniline substituted derivatives), [Ru(2)(Xap)(4)](2)(μ-C(6)) (1), were prepared. Compounds 1 reacted with 1 equiv of tetracyanoethene (TCNE) to yield the cyclo-addition/insertion products [Ru(2)(Xap)(4)](2){μ-C≡CC(C(CN)(2))-C(C(CN)(2))C≡C} (2) and 1 equiv of Co(2)(dppm)(CO)(6) to yield the η(2)-Co(2) adducts to the middle C≡C bond, [Ru(2)(Xap)(4)](2)(μ-C(6))(Co(2)(dppm)(CO)(4)) (3). Voltammetric and spectroelectrochemical studies revealed that (i) two Ru(2) termini in 1 are sufficiently coupled with the monoanion (1(-)) as a Robin-Day class II/III mixed valence species; (ii) the coupling between two Ru(2) is still significant but somewhat weakened in 3; and (iii) the coupling between two Ru(2) is completely removed by the insertion of TCNE in 2. The attenuation of electronic couplings in 2 and 3 was further explored with both the X-ray diffraction study of representative compounds and spin-unrestricted DFT calculations.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States.
authors.forename: Bin
authors.initials: B
authors.lastname: Xi
authors.forename: Isiah P-C
authors.initials: IP
authors.lastname: Liu
authors.forename: Guo-Lin
authors.initials: GL
authors.lastname: Xu
authors.forename: Mohommad M R
authors.initials: MM
authors.lastname: Choudhuri
authors.forename: Maria C
authors.initials: MC
authors.lastname: DeRosa
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Crutchley
authors.forename: Tong
authors.initials: T
authors.lastname: Ren