Bis-Argentivorous Molecules Bridged by Phenyl and 4,4′-Biphenyl Groups: Structural and Dynamic Behavior of Silver Complexes

• Published in: Inorganic chemistry Vol. 60; no. 20; pp. 15159 - 15168
• Main Authors: Ju, Huiyeong, Horita, Hiroki, Iwase, Miki, Kaneko, Nanae, Yagi, Ken-ichi, Ikeda, Mari, Kuwahara, Shunsuke, Habata, Yoichi
• Format: Journal Article
• Language: English
• Published: American Chemical Society 18-10-2021
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.1c01500

Bis-argentivorous molecules (L a and L b ), which have phenyl and 4,4′-biphenyl groups as linkers, have been prepared. The structures of Ag+ complexes with the new ligands (L a and L b ) were investigated in solution and the solid state. The CSI-MS and 1H NMR titration of L a and L b with Ag+ show 1:1 and 1:2 complexes depending on the [Ag+]:[L] ratios. In the solid-state structures, single crystals of L a and L b with 2 equiv of Ag+ were prepared. X-ray crystallography of the silver­(I) complexes with L a and L b showed that an intramolecular racemic structure (Δ­(δδδδ)­Λ­(λλλλ) form) and a racemic mixture of Δ­(δδδδ)­Δ­(δδδδ) and Λ­(λλλλ)­Λ­(λλλλ) forms were formed, respectively. The dynamic 1H NMR studies suggest the following: (i) the activation entropies (ΔS ⧧) of the side arm rotations in the Ag+ complex with L a were all negative, indicating restricted rotation of the side arms due to their shortness, and (ii) the ΔS ⧧ values of the Ag+ complexes with L b were negative only when the side arms of both cyclens rotated simultaneously, and the ΔS ⧧ values for the 1:1 and 1:2 complexes were positive when one cyclen side arm was rotated. These values of ΔS ⧧ indicate that the biphenyl side arms between the two cyclens are not long enough to rotate the ring freely.