Double helical assembly of imino nitroxyl diradicals by silver(I) ions

Silver(i) complexes of bis- and tris-(pyrazolyl)azine derivatives – dimers, coordination polymers and a pentametallic assembly

“…The tpp ligands in this case are only coordinated through the tridentate metalbinding domain, with the pendant 4-pyrazolyl groups projecting from the periphery of the molecules. The dimeric helicate motif is well-known in coinage metal complexes of tris-heterocycle ligands, [4][5][6][15][16][17][18][20][21][22][23][24] including derivatives of bpp (Scheme 1). 21 Rare examples of such dimeric helicates associating into higher order molecular assemblies through unsupported dispersion interactions are known.…”

“…2,3 Alternatively, [Ag n (terpy) m ] n+ helicate structures are also wellknown, usually in dimeric complexes ( n = m = 2) [4][5][6][15][16][17][18] although larger molecular 1,6 or polymeric 6 helicate assemblies of this type are also known. Other "terpyridine analogue" trisheterocycles also mostly yield square planar dimers 19 or helicate assemblies [20][21][22][23][24][25][26] when complexed to silver(I). However examples of circular helicates, 22 molecular squares 27 and rare homoleptic octahedral silver(I) complexes 23 have also been reported with such ligands.…”

Modulating the Magnetic Properties of Copper(II)/Nitroxyl Heterospin Complexes by Suppression of the Jahn–Teller Distortion

“…This phenomenon is best studied in [Cu(hfac)2]/nitronyl nitroxide coordination polymers, 11 but molecular complexes of chelating nitroxyl ligands can also exhibit the effect. 12 With this in mind, we targeted the heteroleptic complexes [Cu(L)L 1 ] 2+ , where L 1 is the biradical 2,6-bis{1-oxyl-4,4,5,5tetramethyl-4,5-dihydro-1H-imidazol-2-yl}pyridine [13][14][15][16][17][18] and L is another tridentate ligand (Charts 2 and S1). The steric influence of the L 1 methyl substituents should promote a Jahn-Teller elongation along the Cu−iminonitroxyl (IMNT) bonds (structure A).…”

18 Supramolecular coordination chemistry

“…6 The linear nonapyridine L 5 forms trinuclear double helicates with Co 2 and Cu 2 in which the ligand is partitioned into terdentate binding domains. 10 In the mononuclear complex [Zn (L 19 )] the ligand has a helical twist around the metal, whose sense is dictated by the chirality of the substituent R such that diastereomeric excesses of b95% are obtained (cf. 7 The enantiopure chiral ligands L 6 form a mixture of mononuclear and polynuclear helical complexes such as [Ag(L 6 ) 2 ] , [Ag 2 (L 6 ) 2 ] 2 , [Ag 3 (L 6 ) 3 ] 3 amongst others; the relative concentrations of the different species are solvent-and concentration-dependent.…”

“…8 In the helical dimers [Cu I 2 (L 7 ) 2 ] 2 the coordination mode of the ligand, and in particular the way in which the three donor atoms are shared between two metals, depends on the nature of the substituent R. 9 [Ag 2 (L 8 ) 2 ] 2 is a double helicate in which the nitroxide radicals are ferromagnetically coupled within each ligand, but antiferromagnetically coupled between the two ligands of a complex cation. 10 In dinuclear helicates of Cu and Cu 2 with the asymmetric ligand L 9 the two ligands are mutually ``head to tail'' (i.e. oriented in opposing directions).…”