A remarkably stable copper(I) ethylene complex: synthesis, spectroscopy and structure

Abstract

The novel copper(i) ethylene complex [Bu t 2 P(NSiMe 3 ) 2k 2 N]Cu(h 2 -C 2 H 4 ) and its norbornene analogue have been synthesized and characterized and their solid state structures determined.

A study of Cu(I)‐ethylene complexation for olefin–paraffin separation

“…X-ray crystallography should show that complexation increases the alkene bond distance, and indeed, this is often the case. 10,11,19,20,22 However, this bond lengthening is far less than that predicted given the degree of change in the vibrational spectra. 10,22 In fact, in the tris-ethylene complex [Cu(C 2 H 4 ) 3 ]…”

“…Given a bidentate ligand, the complex forms a trigonal planar structure. 8,10,11,13,[19][20][21][22][23] Given a tridentate ligand, the complex forms a distorted tetrahedral structure. 22,24,25 Figure 4 below illustrates these two structures, where a, b, and c represent ligand attachment sites.…”

“…19 Most Cu(I)-ethylene complexes span these two extremes of 1 H NMR chemical shifts. 8,10,11,13,20,22,24 The amount of the chemical shift has been hypothesized to increase with increasing basicity (pKa) of the auxiliary ligands, as increasingly basic ligands will donate more electron density to the Cu(I) ion. The metal center sheds this electron density through increased p-backbonding, which will increase the chemical shift of the signal observed.…”

“…The metal center sheds this electron density through increased p-backbonding, which will increase the chemical shift of the signal observed. 7,8,11,20 Figure 9 below illustrates this effect for an array of ligands of Cu(I)-ethylene complexes. 8 The ethylene 1 H NMR signal appears as a single peak, indicating the fast exchange of uncomplexed and complexed ethylene.…”

Thermally Stable Gold(I) Ethylene Adducts: [(HB{3,5‐(CF3)2Pz}3)Au(CH2CH2)] and [(HB{3‐(CF3),5‐(Ph)Pz}3)Au(CH2CH2)]

“…The upfield shift of the 13 C NMR resonance is also high compared to other coinagemetal family members (i.e., Dd(C) (d(C) complex Àd(C) ethylene ) for Cu, Ag, and Au are À34.4, À18.6, À59.8 ppm, respectively). The upfield shift of the 13 C and 1 H NMR resonance of ethylene signal has been attributed to the increased metal-toethylene p-back-donation contribution. [4,12] Thus, these NMR data point to a significantly higher p-back-donation component in the gold(I)-ethylene bond than in the lighter members, and are in good agreement with the latest computational work and NMR spectroscopic studies of gold(I) ethylene adducts.…”