The Backbone of Success of P,N-Hybrid Ligands: Some Recent Developments

Abstract

Organophosphorus ligands are an invaluable family of compounds that continue to underpin important roles in disciplines such as coordination chemistry and catalysis. Their success can routinely be traced back to facile tuneability thus enabling a high degree of control over, for example, electronic and steric properties. Diphosphines, phosphorus compounds bearing two separated PIII donor atoms, are also highly valued and impart their own unique features, for example excellent chelating properties upon metal complexation. In many classical ligands of this type, the backbone connectivity has been based on all carbon spacers only but there is growing interest in embedding other donor atoms such as additional nitrogen (–NH–, –NR–) sites. This review will collate some important examples of ligands in this field, illustrate their role as ligands in coordination chemistry and highlight some of their reactivities and applications. It will be shown that incorporation of a nitrogen-based group can impart unusual reactivities and important catalytic applications.

Molybdenum Tricarbonyl Complexes Supported by Linear PNP Ligands: Influence of P‐ and N‐Substituents on Relative Stability, Stereoisomerism and on the Activation of Small Molecules

“…Interestingly, for all investigated complexes except 2 g, four instead of two bands are observed for the A'' and A' (2) stretching vibrations in the Raman spectra (Table 2). Complex 2 c, in which this splitting is most pronounced, shows a difference of Δν = 12 and 10 cm À 1 between the A' (2) and A'' bands, respectively.…”

“…For an octahedral complex with facial M(CO) 3 coordination, group theory predicts two bands in the CO stretching region of the IR-and in the Raman-spectrum (A 1 and E). Due to the actual C s -symmetry of complexes 2 a, 2 c, 2 e, 2 f, and 2 g (Figure 4 and Figure S36, S44, S48, and S52), E splits into A'' and A' (2) , in addition to A' (1) which corresponds to the totally symmetric, in-phase stretching mode. In the Raman spectrum, the A' (1) band is found to be very weak for the facial isomer, while the A'' and A' (2) bands are strong, clearly visible in case of 2 c (Figure 2).…”

“…Due to the actual C s -symmetry of complexes 2 a, 2 c, 2 e, 2 f, and 2 g (Figure 4 and Figure S36, S44, S48, and S52), E splits into A'' and A' (2) , in addition to A' (1) which corresponds to the totally symmetric, in-phase stretching mode. In the Raman spectrum, the A' (1) band is found to be very weak for the facial isomer, while the A'' and A' (2) bands are strong, clearly visible in case of 2 c (Figure 2). The meridional isomer, on the other hand, would exhibit an intense A' (1) band.…”

“…PNP ligands have been employed in coordination chemistry with a broad range of metals and coligands. [1][2][3][4][5][6][7][8][9][10] Three main types of these ligands can be distinguished: PNP pincer, tripodal, and linear tridentate ligands. Pincer ligands enforce a meridional coordination mode through their rigid design, which confers, both, high stabilities and catalytic activities to the derived complexes.…”

A Novel Photoluminescent Ag/Cu Cluster Exhibits a Chromic Photoluminescence Response towards Volatile Organic Vapors

“…Some coordination compounds can serve as photoluminescent (PL) probes for VOCs with a rapid and reversible switching or chromic response [ 1 , 2 , 3 , 4 , 5 ]. Coinage metal complexes have been developed with useful photophysical properties such as sensitive and selective emission color changes under external stimuli [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. Bimetallic Ag/Cu complexes have attracted considerable attention in this respect due to their low cost and rich luminescence behaviors.…”