Multi-pyridine decorated Fe(ii) and Ru(ii) complexes by Pd(0)-catalysed cross couplings: new building blocks for metallosupramolecular assemblies

Abstract

Eight metal complexes of the type [M(tpy) 2 ] 2+ (tpy = 2,2':6',2''-terpyridine) featuring four pendant pyridine rings are reported and characterised by NMR, MS, absorption spectroscopy and electrochemical methods. Palladium-mediated Suzuki and Sonogashira cross-coupling reactions were performed on both free 4'-(3,5-dibromophenyl)-tpy and its Ru(II) complex in good yields. The ready N-alkylation of the pendant pyridyl units has significant influence on the absorption and electrochemical reduction of the complexes, processes which are localised on the periphery and leaves the [Ru(tpy) 2 ] 2+ core essentially unaffected. The binding of metal ions by the free pyridines is also demonstrated as means of assembling larger ordered non-covalent structures.

Self-assembled supramolecular cages containing ruthenium(ii) polypyridyl complexes

“…1). 20 Square planar Pd(II) complexes are well suited to binding pyridyl ligands to form metallosupramolecular structures, using approaches pioneered by Fujita 21 and Stang. 22 Reaction of [Ru(1) 2 ](PF 6 ) 2 with two equivalents of Pd(dppp)(OTf) 2 (dppp = 1,3-diphenylphosphinopropane) in nitromethane at room temperature (Fig.…”

New ruthenium(II) complexes of 2,2′:6′,2″-terpyridine derivatives as supramolecular building blocks

“…Furthermore, the resulting boronic acid functionalized complexes were unstable with respect to hydroxylation to form the corresponding phenols. The complexes reported here are suitable for Suzuki cross coupling reactions [9,11] to form dimetallic expanded ligands, [8] provided they are reacted soon after preparation. The bromofunctionalized complexes are stable and also suitable for other Pd(0) catalyzed cross coupling reactions.…”

“…[7] In order to assemble larger structures additional metal ion binding groups are appended to form 'expanded ligands' [8] which can be combined with labile metal ions to self-assemble into the desired architectures. With this goal in mind, our approach was to use Pd(0)-mediated cross-coupling reactions on inert ruthenium(II) complexes [9] to prepare large bridging units which feature metal ion binding groups on the periphery. Pyridyl donor groups are particularly appealing due to their ability to coordinate to a wide range of metal ions, including to square planar Pd(II) centers [10] and are the basis of this work.…”

“…Herein we report eight new heteroleptic ruthenium(II) complexes of 4'-substituted 2,2':6',2''-terpyridine ligands featuring either pendant pyridyl units, aryl bromides or aryl boronic acids which can act as supramolecular building blocks. [9,11] 2 Experimental…”

Tetratopic bis(4,2′:6′,4′′-terpyridine) and bis(3,2′:6′,3′′-terpyridine) Ligands as 4-Connecting Nodes in 2D-Coordination Networks and 3D-Frameworks

“…Newkome's work in this field has been inspirational as demonstrated by selected, recently reported architectures [2,3,4]. The incorporation of additional donor functionalities in the 4'-positions of the ligands in a {M(tpy) 2 } unit generates an 'expanded ligand' (Scheme 1) (Scheme 1) [5] with the potential for the assembly of multinuclear systems [6][7][8][9][10][11][12]. Scheme 1.…”