title: Bis-alkynyl diruthenium compounds with built-in electronic asymmetry: toward an organometallic Aviram-Ratner diode.
abstract: Conditions to prepare trans-[Ru2(dmba)4(C[triple chemical bond]CAr)2] from [Ru2(dmba)4(NO(3))2] (DMBA=N,N'-dimethylbenzamidinate) and HC[triple chemical bond]CAr were optimized; Et2NH was found to be the most effective among a number of weak bases in facilitating the product formation. Furthermore, a series of unsymmetric trans-[(ArC[triple chemical bond]C)Ru(2)(dmba)4(C[triple chemical bond]CAr')] compounds were prepared under optimized conditions, in which one or both of Ar and Ar' are donor (NMe2)-/acceptor (NO(2))-substituted phenyls. While the X-ray crystallographic studies revealed a minimal structural effect upon donor/acceptor substitution, voltammetric measurements indicated a significant influence of substituents on the energy level of frontier orbitals. In particular, placing a donor and an acceptor on the opposite ends of trans-[(ArC[triple chemical bond]C)Ru2(dmba)4(C[triple chemical bond]CAr')] moiety results in an energetic alignment of frontier orbitals that favors a directional electron flow, a necessary condition for unimolecular rectification.
authors.affiliation: Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Jie-Wen
authors.initials: JW
authors.lastname: Ying
authors.forename: Antoinette
authors.initials: A
authors.lastname: Cordova
authors.forename: Tony Y
authors.initials: TY
authors.lastname: Ren
authors.forename: Guo-Lin
authors.initials: GL
authors.lastname: Xu
authors.forename: Tong
authors.initials: T
authors.lastname: Ren