Structural Characterization of Organocuprate reagents. EXAFS Spectroscopy and ab Initio Calculations

The Use of15N NMR Spectroscopy To Resolve the “Higher Order Cyanocuprate” Controversy:15N,6Li, and13C NMR Spectroscopic Investigations of CuCN-Derived Butyl Cuprates

“…We denote these hydrated methyl derivatives, which are the usual model compounds, [9,11] as 1 a ± 6 a. They were also performed on CN À and TMSCN.…”

“…[5] Subsequently, Bertz showed that the 13 C NMR chemical shifts of the cuprates prepared from two equivalents of RLi and CuCN or CuI were the same and that the shift of the CN carbon atom was independent of the electronic nature of R. [6] In contrast, the chemical shifts of the CN carbon atoms in the ªlower orderº cyanocuprates RCu(CN)Li vary with R. [3,6] These observations and the absence of 2 J in the 2:1 compounds cast grave doubt on the higher order formulation R 2 Cu(CN)Li 2 . [4,7] Extended X-ray absorption fine structure (EXAFS) [8,9] investigations by Penner-Hahn, Knochel, Frenking et al and IR [10] studies by Penner-Hahn, Snyder et al supported the conclusions of these NMR studies. Theoretical investigations by Snyder et al [11] and Penner-Hahn, Knochel, Frenking et al [9] indicated that higher order structures are 20 ± 30 kcal mol À1 higher in energy than lower order alternatives.…”

“…[4,7] Extended X-ray absorption fine structure (EXAFS) [8,9] investigations by Penner-Hahn, Knochel, Frenking et al and IR [10] studies by Penner-Hahn, Snyder et al supported the conclusions of these NMR studies. Theoretical investigations by Snyder et al [11] and Penner-Hahn, Knochel, Frenking et al [9] indicated that higher order structures are 20 ± 30 kcal mol À1 higher in energy than lower order alternatives.…”

Structure and reactivity of cyanocuprates containing the monoanionic C,N-chelating aminoaryl ligand [C6H4CH2NMe2-2]−

“…: q31-30-2531813; fax: q31-30-2523615; e-mail: g.vankoten@chem.uu.nl four structures [8]. Moreover, recent spectroscopic studies (EXAFS [9][10][11]) and molecular weight determinations [15] seemed also to support the structural proposals C and D. …”

Synthesis and Characterization of (THF)3Li(NC)CU(C6H3-2,6-Mes2)and Br(THF)2Mg(C6H3-2,6-Trip2) (Mes = C6H2-2,4,6-Me3; Trip = C6H2-2,4,6-i-Pr3): The Structures of a Monomeric Lower-Order Lithi

“…These findings were later corroborated by EXAFS 9 and IR 10 data as well as by theoretical calculations. 11,12 Consequently, it was suggested that there was no such higher-order cyanocuprate species formed. The claim for the non-existence of higher-order cyanocuprates was strengthened by the independent isolation of two polymeric lithium cyanocuprate compounds: [(tBu) 2 Cu{Li(THF)(pmteda) 2 3 ] in THF solvent.…”