New Media for Classical Coordination Chemistry: Phase Transfer of Werner and Related Polycations into Highly Nonpolar Fluorous Solvents

Abstract

Optimized procedures for the previously reported conversions of 1,3-diiodobenzene and perfluorohexyliodide (Rf6I; copper, DMSO, 140 °C) to 1,3-C6H4(Rf6)2 (3; 86-70%) and 3 to Br(3,5-C6H3(Rf6)2 (2; NBS, H2SO4/CF3CO2H; 88-75%) are described. The latter is converted (t-BuLi, BCl3) to the "fluorous BArf" salt NaB(3,5-C6H3(Rf6)2)4 (1 or NaBArf6; 77-70%), as given earlier. When orange aqueous solutions of [Co(en)3]Cl3 (en = ethylenediamine) are treated with perfluoro(methylcyclohexane) (PFMC) solutions of 1 (1:3 mol ratio), the aqueous phase decolorizes and [Co(en)3](BArf6)3 can be isolated from the fluorous phase (96%). Similar reactions with the trans-1,2-cyclohexanediamine analogue [Co(R,R-chxn)3]Cl3 and [Ru(bipy)3]Cl2 give [Co-(R,R-chxn)3](BArf6)3 (92%) and [Ru(bipy)3](BArf6)2 (95%). All of these salts are isolated as hydrates and exhibit toluene/PFMC partition coefficients of ≤1:≥99, establishing that the anion BArf6(-) can efficiently transport polar polycations into highly nonpolar fluorous phases. When equal volumes of CH2Cl2 and PFMC are charged with the "nonfluorous" BArf (B(3,5-C6H3-(CF3)2)4) salt [Co(en)3](BArf)3 and 3.0 equiv of the fluorous salt NaBArf6, the cobalt trication partitions predominantly into the fluorous phase (64:36). The arene 2 crystallizes in a polar space group (tetragonal, I4, Z = 8) with fluorous and nonfluorous domains and all eight bromine atoms located essentially on one face of the unit cell.

Octahedral Werner complexes with substituted ethylenediamine ligands: a stereochemical primer for a historic series of compounds now emerging as a modern family of catalysts

“…8 Not surprisingly, coordination compounds can function similarly, and frequently offer architectures and binding site arrays that have no counterparts in organic systems. Another has been the development of lipophilic 4 and/or fluorophilic 9 Werner complexes, such that catalysis can be conducted in the absence of water, which would otherwise saturate (or compete with substrate access to) the hydrogen bond donor sites. environments, and it is left to motivated readers to derive the extensive families of stereoisomers that can result.…”

Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity

“…Work-up gave the target compound 1,3-R f6 C 6 H 4 I in 60% yield (based upon limiting R f6 I). Some of the previously reported dialkylation product 1,3-(R f6 ) 2 C 6 H 4 was also formed [ 47 – 48 ], but was easily separated due to its differential fluorophilicity (extraction of a CH 3 CN solution with perfluorohexane). An analogous procedure with R f10 I gave the higher homolog 1,3-R f10 C 6 H 4 I in 50% yield [ 9 ], and a lesser amount of what was presumed to be the dialkylation product.…”

“…Syntheses and reactions, aryl iodides with two perfluoroalkyl groups. In a previously reported procedure [ 48 ], the diiodide 1,3-C 6 H 4 I 2 was treated with copper (5.1 equiv) and R f6 I (2.2 equiv) in DMSO at 140 °C. As shown in Scheme 6 (top), the bis(perfluorohexyl) adduct 1,3-(R f6 ) 2 C 6 H 4 , which was the undesired byproduct in Scheme 5 (top), was isolated in 75% yield.…”

Phase and redox shifted four iron/four sulfur clusters: fluorous analogs of metalloenzyme cofactors

“…The doubly fluorous salts (14,15) gave satisfactory microanalyses. However, the carbon values of other salts were slightly off (0.67-0.70% for 4 and 9), and in two cases the sulfur values similarly deviated (12,16).…”

“…11 Horváth, Rábai, our group, and many others have demonstrated that by introducing appropriate numbers of perfluoroalkyl groups ((CF 2 ) n−1 CF 3 = R fn ) of sufficient lengths, a variety of neutral molecules can be rendered soluble in nonpolar fluorous liquid phases, such as perfluorohexanes . 12 We have also shown that many ionic compounds, 13 such as organic ammonium and phosphonium salts, as well as salts of inorganic polycations, 14 can similarly be rendered soluble in fluorous phases. 15,16 As such, it was natural to speculate whether the right combination of fluorous thiolate substituents and fluorous cations might render salts of the type nQ + [Fe 4 S 4 (SR) 4 ] n− soluble in fluorous media.…”