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. 2023 Dec 22;43(1):14-20.
doi: 10.1021/acs.organomet.3c00467. eCollection 2024 Jan 8.

Comparative Analysis of the Donor Properties of Isomeric Pyrrolyl Phosphine Ligands

Vicky A Osenga  1 , Nolan C Sykes  1 , Sopheak Pa  1 , Michael K Bambha  1 , Nathan D Schley  2 , Miles W Johnson  1
Affiliations

Comparative Analysis of the Donor Properties of Isomeric Pyrrolyl Phosphine Ligands

Vicky A Osenga et al. Organometallics. .

Abstract

Understanding the net donor and electronic properties of pyrrole-based phosphines is critical for guiding their use as ligands. In this study, we compare two isomeric 1- and 2-(diphenylphosphino)methylpyrroles (L1 and L2, respectively) to determine the degree to which N-(phosphino)pyrroles are distinct from aryl- and 2-pyrrolyl phosphines. Ruthenium, rhodium, platinum, and gold complexes as well as selenide derivatives of these ligands are examined using NMR and IR spectroscopy, X-ray crystallography, and cyclic voltammetry. Ligand L2 exhibits net donor properties similar to those of the o-tolyl analogue L3, while L1 shows attenuated electron donation ability. Additionally, a model nickel-catalyzed Kumada coupling reaction using these three ligands was investigated.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Representative examples of phosphinopyrrole ligands.
Scheme 1
Scheme 1. Synthesis of Model Phosphines
Figure 2
Figure 2
Synthesis of LAuCl complexes and key metrics.
Figure 3
Figure 3
Solid-state structures of LAuCl. Thermal ellipsoids are shown at 50% probability. Disorder, solvents, and all hydrogen atoms have been omitted for clarity.
Figure 4
Figure 4
Synthesis of phosphine selenides and the JP–Se coupling constants. aLiterature value.
Figure 5
Figure 5
Synthesis of trans-(L)2Rh(CO)Cl complexes, νCO values, and key metrics. aAverage P–Rh bond length.
Figure 6
Figure 6
Solid-state structures of trans-(L)2Rh(CO)Cl with thermal ellipsoids are shown at 50% probability. Disorder, solvents, and all hydrogen atoms are omitted for clarity.
Figure 7
Figure 7
Thin-film ATR–IR spectra of trans-(L)2Rh(CO)Cl.
Figure 8
Figure 8
Synthesis of (η6-p-cymene)Ru(L)Cl2 complexes and their Epa. aE1/2 = 0.70 V.
Figure 9
Figure 9
Cyclic voltammograms of (η6-p-cymene)Ru(L)Cl2 in CH2Cl2. Conditions: scan rate: 100 mV/s; supporting electrolyte: 0.1 M [n-Bu4N][PF6]; working electrode: glassy carbon; auxiliary electrode: platinum wire; reference: silver wire referenced to the Fc/Fc+ couple.
Figure 10
Figure 10
Synthesis of platinum complexes cis-(L2)2PtCl2 and their Pt–Cl bond lengths. aAverage P–Pt bond length. bAverage Pt–Cl bond length.
Figure 11
Figure 11
Solid-state structures of cis-(L2)2PtCl2 and cis-(L3)2PtCl2 with thermal ellipsoids shown at 50% probability. Solvents and all hydrogen atoms are omitted for clarity.
Figure 12
Figure 12
Performance of model ligands in a nickel-catalyzed Kumada cross-coupling reaction. Reported yields are an average of duplicate runs.
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References

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