Clusters as ligands: Synthesis, structure and coordination chemistry of ruthenium clusters derived from 4- and 5-ethynyl-2,2′-bipyridine

Abstract

The reaction of [Ru 3 (CO) 10 (µ-dppm)] (1) with 4-ethynyl-2,2'-bipyridine (2) or 5ethynyl-2,2'-bipyridine (3) affords the Ru 3 C 2 clusters [Ru 3 (µ-H)(µ 3 -C 2 bpy)(CO) 7 (dppm)] (bpy = 4-bpy, 4 (22%); bpy = 5-bpy, 5(55%)). Complexes 4 and 5 have been fully characterised by NMR spectroscopy, with 2D-COSY methods being used to aid 1 H NMR assignments, and single crystal X-ray diffraction. The pendant bipyridyl moiety presents as a site for further reaction using the 'Tinkertoy' approach, and subsequent reactions of 4 and 5 with PdCl 2 (NCPh) 2 affords the bimetallic complexes [Ru 3 (µ-H){µ 3 -C 2 bpy(κ 2 -N",N-PdCl 2 )}(CO) 7 (dppm)] bpy = 4-bpy, 6 (55%); bpy = 5-bpy, 7(35%)). † Dedicated to memory of Professor Lord Sir Jack Lewis, FRS, a true organometallic pioneer. ! 2!

Coordinating Tectons. Experimental and Computational Infrared Data as Tools To Identify Conformational Isomers and Explore Electronic Structures of 4-Ethynyl-2,2′-bipyridine Complexes

“…Robust, and ideally modular, synthetic methodologies that permit ready assembly of metal-containing compounds and complexes would allow facile exploration of the chemical, physical, and optoelectronic features provided by metal complexes and design of new materials. Such modular methodologies for the construction of large heterometallic complexes which take advantage of the multiple coordination sites offered by ethynyl bipyridines was previously pursued by Lang in his “Tinkertoy” approach. − We have been recently focused on an allied approach to the construction of bimetallic complexes through the preparation of modular organometallic “coordinating tectons”. − A series of bimetallic complexes of the well-studied bifunctional ligand 5-ethynyl-2,2′-bipyridine were synthesized by this approach, and weak electronic communication was observed between two metal centers across this ligand . Indeed, the electronic interactions between metal termini separated by an organic functionality, M–bridge–M′, are often investigated in order to define the intramolecular electron transfer (or wirelike) characteristics of the assembly. − Investigations of organometallic complexes in this area have focused on the mixed-valence characteristics of bimetallic complexes derived from bridging moieties such as polyynes, − oligo­(phenylene)­ethynylenes, and bis­(terpyridine)metal complexes .…”

Evaluation of the 5-ethynyl-1,3,3-trimethyl-3H-indole ligand for molecular materials applications

“…[8,17,18] We have previously investigated the electro-optical properties of pyridyl and bipyridyl moieties in σ-alkynyl, vinylidene and allenylidene organometallic complexes. [19][20][21][22][23] Herein, the synthesis of a series of organometallic complexes derived from the 5-ethynyl-3H-indole moiety is reported and their physical and chemical properties are described.…”