Connectivity-Dependent Conductance of 2,2'-Bipyridine-Based Metal Complexes

Yahia Chelli; Nicolò Ferri; Andrea Vezzoli; Ross J Davidson; James Morris; Richard J Nichols; Simon J Higgins; Sara Sangtarash; Hatef Sadeghi; Dmitry S Yufit; Andrew Beeby

doi:10.1021/acsomega.3c06555

Connectivity-Dependent Conductance of 2,2'-Bipyridine-Based Metal Complexes

ACS Omega. 2023 Dec 14;8(51):48958-48965. doi: 10.1021/acsomega.3c06555. eCollection 2023 Dec 26.

Affiliations

¹ School of Engineering, University of Warwick, Library Road, Coventry CV4 7AL, U.K.
² Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, U.K.
³ Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K.

Abstract

The present work provides an insight into the effect of connectivity isomerization of metal-2,2'-bipyridine complexes. For that purpose, two new 2,2'-bipyridine (bpy) ligand systems, 4,4'-bis(4-(methylthio)phenyl)-2,2'-bipyridine (L^meta) and 5,5'-bis(3,3-dimethyl-2,3-dihydrobenzothiophen-5-yl)-2,2'-bipyridine (L^para) were synthesized and coordinated to rhenium and manganese to obtain the corresponding complexes MnL^meta(CO)₃Br, ReL^meta(CO)₃Br, MnL^para(CO)₃Br, MoL^para(CO)₄ and ReL^para(CO)₃Br. The experimental and theoretical results revealed that coordination to the para system, i.e., the metal ion peripheral to the conductance path, gave a slightly increased conductance compared to the free ligand attributed to the reduced highest occupied molecular orbital (HOMO)-least unoccupied molecular orbital (LUMO) gap. The meta-based system formed a destructive quantum interference feature that reduced the conductance of a S···S contacted junction to below 10^-5.5G_o, reinforcing the importance of contact group connectivity for molecular wire conductance.