# Synthesis and Characterization of a Copper Complex Supported by a Z‑type SbV Ligand: XPS and DFT Study of Electronic Structure

## TL;DR

The paper reports the synthesis and analysis of a copper complex with an antimony ligand, revealing electronic structure insights through XPS and DFT.

## Contribution

A novel copper complex with a Z-type SbV ligand is synthesized and its electronic structure is analyzed using XPS and DFT.

## Key findings

- The Cu 2p binding energy is 0.8 eV higher in the Sb-containing complex compared to a related non-Sb complex.
- The CuII/CuI redox potential is shifted 670 mV more positive in the Sb-containing complex.
- Computational studies confirm a weak Cu(I) → Sb(V) interaction with Sb(V) acting as a Z-type ligand.

## Abstract

We describe the synthesis
and characterization of a Cu­(I)
complex,
{Q3Sb­(o-chlor)}­Cu­(OTf) (Q = 8-quinolinyl;
OTf = trifluoromethanesulfonate; o-chlor = o-choranil), supported by the Sb­(V) ligand Q3Sb­(o-chlor). The complex {Q3Sb­(o-chlor)}­Cu­(OTf) was experimentally characterized via 1H, 13C­{1H}, and 19F­{1H} NMR spectroscopy, elemental analysis, single-crystal X-ray
diffraction, and X-ray photoelectron spectroscopy (XPS) as well as
examined computationally with density functional theory (DFT) calculations.
Variable temperature 1H NMR spectroscopy (20 to −110
°C) indicates temperature-dependent fluxional processes for {Q3Sb­(o-chlor)}­Cu­(OTf) and uncoordinated Q3Sb­(o-chlor). The electron density of Cu for
{Q3Sb­(o-chlor)}­Cu­(OTf) was probed by comparing
CuII/CuI redox potential and Cu 2p electron
binding energies, using XPS, with a related non-Sb-containing complex,
(TMQA)­Cu­(OTf) (TMQA = tris­(quinolin-2-ylmethyl)­amine). The E
1/2 of the CuII/CuI redox
of {Q3Sb­(o-chlor)}­Cu­(OTf) is shifted 670
mV more positive than that of (TMQA)­Cu­(OTf). XPS spectra of {Q3Sb­(o-chlor)}­Cu­(OTf) and (TMQA)­Cu­(OTf) indicate
a 0.8 eV higher Cu 2p binding energy for {Q3Sb­(o-chlor)}­Cu­(OTf). Computational studies of the molecular
orbitals and localized natural bonding orbitals (NBOs) are consistent
with a weak Cu­(I) → Sb­(V) interaction for {Q3Sb­(o-chlor)}­Cu­(OTf), for which Sb­(V) acts as a Z-type ligand.