title: 2,2':6',2''-terpyridine substituted in the 4'-position by the solubilizing and sterically demanding tert-butyl group: a surprisingly new ligand.
abstract: We describe the synthesis and characterization of 4'-tert-butyl-2,2':6',2''-terpyridine (4'-(t)Butpy, 1), a convergent tpy ligand that exhibits both a sterically demanding and solubilizing 4'-substituent. In the solid state, molecules of 1 pack with alternating tpy and tert-butyl domains, and the bulky alkyl substituents prevent the molecules from engaging in the face-to-face π-interactions which are typical of simple tpy ligands. Instead, the predominant packing forces involve CH···N hydrogen bonds and weak CH···π contacts. The syntheses of the homoleptic complexes [M(1)(2)][PF(6)](2) (M = Fe, Co, Zn and Ru) and the heteroleptic [Ru(tpy)(1)][PF(6)](2) are described. The complexes have been fully characterized in solution, including the (1)H NMR spectroscopic characterization of the paramagnetic [Co(1)(2)][PF(6)](2). Cyclic voltammetric data are consistent with the tert-butyl substituent being slightly electron releasing. The single crystal structures of [Zn(1)(2)][PF(6)](2) and [Ru(1)(2)][PF(6)](2) have been determined; the compounds are essentially isomorphous. The packing of the cations is such that the tert-butyl substituents are accommodated in pockets between the tpy domains of adjacent cations, and as a consequence, the {M(tpy)(2)}-embrace that is a ubiquitous feature of many related structures is not observed.
authors.affiliation: Department of Chemistry, University of Basel, Basel, Switzerland. edwin.constable@unibas.ch
authors.forename: Edwin C
authors.initials: EC
authors.lastname: Constable
authors.forename: Nik
authors.initials: N
authors.lastname: Hostettler
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Housecroft
authors.forename: Peter
authors.initials: P
authors.lastname: Kopecky
authors.forename: Markus
authors.initials: M
authors.lastname: Neuburger
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Zampese