Coordination behavior of PPh2{C6H4[CH2N(CH2CH2)2O]-2}: Case study CdCl2[PPh2{C6H4[CH2N(CH2CH2)2O]-2}

Ancuța Covaci,Cristian Silvestru,Anca Silvestru

doi:10.1515/mgmc-2021-0029

Abstract

Abstract The reaction between CdCl2 and PPh2{C6H4 [CH2N(CH2CH2)2O]-2} (1) in a 1:1 molar ratio resulted in the cadmium(II) complex CdCl2[PPh2{C6H4[CH2N(CH2CH2)2O]-2}] (2). The complex 2 was characterized in solution by NMR spectroscopy (1H, 13C, and 31P). Single-crystal X-ray diffraction studies revealed no intramolecular N→P interaction in 1. The phosphane ligand behaves as a P,N chelating moiety in the cadmium complex 2, thus resulting in a species containing distorted tetrahedral environments around cadmium and phosphorus. Short intermolecular interactions CH‧‧‧π aryl and CH‧‧‧O in 1 and CH‧‧‧π aryl and CH‧‧‧Cl in 2 resulted in supramolecular networks.

Highlights

Homo- and heteroleptic triorganophosphanes were frequently used as ligands for transition metal complexes with significant catalytic properties (Alonso et al, 2003; Brunner et al, 1999; Fierro-Arias et al, 2005; Selvakumar et al, 2000)
Several structural features should be mentioned with regard to the metal complexes with such ligands: (i) the intramolecular N→M coordination results in six membered MPC3N metallacycles which undergo a conformational exchange in solution (Scheme 1), as it was observed for the mononuclear Pd, Pt, and Rh derivatives (Alonso et al, 2003; Fierro-Arias et al, 2005; Kapteijn et al, 1996; Pfeiffer et al, 2000); (ii) the crystals of these complexes usually contain λ and δ isomers, as a result of the chirality induced to the metal by the N→M interaction (Connelly et al, 2005). (iii) the phosphanes containing two or three organic groups with pendant arms behave as P,N chelating moieties in mononuclear metal complexes, in most cases with only one nitrogen involved in coordination to the metal centre
During last years we reported several metal complexes with triaryl phosphanes capable for a P,N coordination, e.g., CoCl2PPhx[C6H4(CH2NMe2)-2]3-x (Mitea et al, 2013) and CuXPPhx[C6H4(CH2NMe2)-2]3-x (R = Me, X = Cl, Br, I; Covaci et al, 2014; R = Et, X = Cl; Șuteu et al, 2018), as well as the group 12 metal complexes MCl2PPhx[C6H4(CH2NMe2)-2]3-x (x = 0-2, M = Zn, Cd, Hg; Dobri et al, 2020)

Summary

Introduction

Homo- and heteroleptic triorganophosphanes were frequently used as ligands for transition metal complexes with significant catalytic properties (Alonso et al, 2003; Brunner et al, 1999; Fierro-Arias et al, 2005; Selvakumar et al, 2000). In order to increase both the stability and the specific activity of the metal complexes, new species were developed, containing aryl groups with pendant arms bearing nitrogen atoms capable for intramolecular coordination, e.g., PPhx[C6H4(CH2NMe2)-2]3-x (x = 0-2). Such phosphanes are expected to behave as P,N chelating ligands. The crystal and molecular structure of the starting phosphane PPh2{C6H4[CH2N(CH2CH2)2O]-2} (1) is discussed

Results

Discussion

Conclusion