Ligand influences on homoleptic Group 12 m-terphenyl complexes

Abstract

Abstract:Three m-terphenyl ligands 2,6-Ar 2 C 6 H 3 -[Ar = 2,6-Me 2 C 6 H 3 (2,6-Xyl); 3,5-Me 2 C 6 H 3 (3,5-Xyl); 2,3,4,5,6-Me 5 C 6 (Pmp)] have been used to stabilise three series of two-coordinate Group 12 diaryl complexes; (2,6-Ar 2 C 6 H 3 ) 2 M [M = Zn, Cd, Hg; Ar = 2,6-Xyl 1-3; 3,5-Xyl 4-6; Pmp 7-9], where differing steric demands on the metal centres are imparted. These are the first homoleptic d-block complexes featuring any of these ligands. Complexes 1-9 have been characterised in solution and the solid state; the analysis of structural changes produced by differences in ligand properties is reported. In particular, complexes 4-6 show smaller C-M-C bond angles and contain secondary ligand interactions that are not seen in the analogous complexes 1-3 and 7-9. † Electronic supplementary information (ESI) available: Crystallographic data for complexes 1-9, molecular structures and crystallographic data for iodides 2,6-Ar 2 C 6 H 3 I (Ar = 2,6-Xyl, 3,5-Xyl, Pmp) and [2,

Structural and electronic studies of substituted m-terphenyl lithium complexes

“…The steric influence of the xylyl flanking groups on the lithium ions is assumed to remain consistent throughout the series and, therefore, not to contribute to changes in the 7 Li{ 1 H} NMR chemical shifts. This is in contrast to previous work on m-terphenyl lithium complexes, where changing the steric bulk of the flanking groups varies the 7 Li{ 1 H} NMR signal 15.…”

“…A series of novel m-terphenyl iodides R-Ar # -I (R = t-Bu, SiMe 3 , Cl, CF 3 ) 28 was synthesised via similar procedures to other terphenyl compounds, 22,[25][26][27][29][30][31][32][33] and H-Ar # -I was obtained following a previously reported method 15,32 (see ESI, section S2). Lithium-halogen exchange reactions performed on these iodide compounds with excess n-butyllithium in s-hexane at 0 °C afforded the m-terphenyl lithium complexes [R-Ar # -Li] 2 (R = t-Bu 1, SiMe 3 2, H 3, Cl 4, CF 3 5) as white powders, according to Scheme 1.…”

“…[1][2][3][4][5][6] Although a plethora of m-terphenyl frameworks have been designed, most studies have been structurally focused, aimed at investigating the effects of steric bulk on the geometries, bonding modes, and reactivities of the resulting compounds. [7][8][9][10][11][12][13][14][15][16][17][18] For instance, the solid state structures observed for a series of m-terphenyl lithium complexes vary depending on the steric demands of the flanking ortho-aryl substituents. 19,20 Increasing the steric bulk of 2,6-Ar 2 C 6 H 3 Li alters its aggregation state from a dimer, 19 to a more crowded dimer featuring η 6 -arene coordination of the flanking aryl groups, 20 to a monomer stabilised by a coordinated molecule of benzene, 20 for Ar = Mes (2,4,6-Me 3 C 6 H 2 ), Dipp (2,6-i-Pr 2 C 6 H 3 ) and Tripp (2,4,6-i-Pr 3 C 6 H 2 ) respectively.…”

Synthesis and structure of bis(m-terphenyl)zinc (2,6-Mes2 C6 H3)2 Zn

“…Differences are observed in the relative orientation of the phenyl rings. Like (C 6 F 5 ) 2 Zn (Sun et al, 1998), [6-(CF 3 )C 6 H 4 ] 2 Zn (Chisholm et al, 2005), the closely related (2,6-Naph 2 C 6 H 3 ) 2 Zn (Gridley et al, 2013), [2,6-(2,6-Xyl) 2 C 6 H 3 ] 2 Zn, [2,6-(3,5-Xyl) 2 C 6 H 3 ] 2 Zn, [2,6-Pmp 2 C 6 H 3 ] 2 Zn (Blundell et al, 2014) and the isoelectronic (2,6-Mes 2 C 6 H 3 ) 2 Hg (Niemeyer and Power, 1997), (2,6-Mes 2 C 6 H 3 ) 2 Zn adopts a nearly C s symmetry, while Mes 2 Zn (Cole et al, 2003;Krieck et al, 2009) and [3,5-(CF 3 ) 2 C 6 H 3 ] 2 Zn (Lai et al, 2012) possess a nearly C 2v symmetry. Presumably due to the large steric congestion, (2,4,6-t-Bu 3 C 6 H 2 ) 2 Zn (Westerhausen et al, 2005) and the related [2,4,6-(CF 3 ) 3 C 6 H 2 ] 2 Zn (Brooker et al, 1992) approach only C 2 symmetry.…”

Supramolecular architectures sustained by delocalised C–I⋯π(arene) interactions in molecular crystals and the propensity of their formation

“…The crystal of 99 162 is of interest in that this is one of two examples of polymorphic structures in this review. While 99 162 is orthorhombic (Pbca), a monoclinic form (C2/c) is also known, 167 in which there are no notable C-I•••π(arene) interactions. 4.…”