Synthesis and Structure of 6-Aminofulvene-2-aldiminate Complexes

Abstract

We report here a synthetic route to bis(N,N'-aryl)-6-aminofulvene-2-aldimine (AFA) ligand systems, specifically Ph(2)-AFAH and Dip(2)-AFAH. The synthesis and structural characterization of a series of Cu(I) complexes [(Ph(2)-AFA)Cu(CNPh)(2)] (2), [(Ph(2)-AFA)Cu(CN(i)Pr)] (3), and [(Dip(2)-AFA)Cu(CN(i)Pr)] (4), from the reaction of the corresponding lithiated AFA systems with Cu-Cl derivatives are reported; notably in the case of [(Ph(2)-AFA)Cu(CNPh)(2)] studies have revealed the existence of two structural isomers (2a and 2b), both of which can be isolated and structurally characterized. Density functional theory (DFT) calculations suggest that the two crystal forms are comparatively close in energy, and geometry optimization reveals a convergence of these two forms to a geometry that more closely resembles the solid-state structure of isomer 2b, having a CH···π interaction. The reactions of the AFA compounds Ph(2)-AFAH and Dip(2)-AFAH with ZnMe(2) and AlMe(3) have also been investigated, and the results of these reactions are described here.

Bis(tert-butyl isocyanide-κC)[4-fluoro-N-({2-[N-(4-fluorophenyl)carboximidoyl]cyclopenta-2,4-dien-1-ylidene}methyl)anilinido-κ2N,N′]copper(I)

“…atom is located 0.6460 (3) Å above the imine portion of the AFA ligand (N2/C6/C7/C11/C12/N3). As with related (AFA)-Cu(CNR) 2 complexes (Willcocks et al, 2011), the bite angle of the AFA ligand in (I) [N2-Cu1-N3 = 106.60 (9) ] is compressed, as a result of pyramidalization at the metal centre.…”

“…The molecular structure of (I) (Fig. 1) shows the Cu I centre to be coordinated by the two N atoms of the AFA ligand and the two divalent C atoms of the isocyanide ligands (Table 1), which are comparable with the Cu I -AFA and Cu I -isocyanide interactions in related complexes (Willcocks et al, 2011), resulting in a coordination environment about the Cu I centre that is best described as approximately tetrahedral. The cyclopentadienyl and imine portions of the AFA ligand are approximately coplanar.…”

“…The diimine-substituted cyclopentadienyl 6-aminofulvene-2aldimines (AFAs) have recently attracted attention as ligands for a variety of metals because of both their similarity to well established ligand systems, such as -diketiminate, aminotroponiminate or anilidoiminate ligands (Willcocks et al, 2011;Bailey et al, 2003Bailey et al, , 2007Bailey et al, , 2010, and their ability to bind to metal centres via the diimine donor groups or via the cyclopentadienyl unit (Bailey et al, 2003(Bailey et al, , 2007.…”

“…Both isocyanide ligands are distorted away from linearity, such that isocyanide ligand C1 is oriented, or bent, towards the imine substituent on N2, and similarly isocyanide ligand C25 is oriented towards the imine substituent on N3. Density functional theory calculations (DFT) on related systems have suggested there is considerable flexibility in the coordination geometry about the copper centres in these systems, with only small energy differences between potential geometric isomers (Willcocks et al, 2011).…”

Synthetic Routes towards Multifunctional Cyclopentadienes

“…[30] Based on the earlier work by Mueller-Westerhoffi nt he seventies andamore recent report in 2002, ag eneral,m odular one-pot synthesis was reportedb yJ ohnson and co-workers. [30,31] An alternative path startingf rom sodium cyclopentadienide was pursued in work by the groups of Bildsteina nd Edelmann (Scheme 8). [32] These approaches allow,i np rinciple, for the introduction of av ariety of different amines and anilines.…”