A series of small bite-angle phosphine-phosphite (P-OP) ligands have been synthesized by a two-step method. The key intermediate was prepared by an unprecedented asymmetric carbonyl reduction of a phosphamide using the CBS (Corey-Bakshi-Shibata) catalyst. The topology of these ligands (a configurationally stable stereogenic carbon with two heteroatom substituents) and their small bite-angle (created by the close proximity of the two ligating groups to the metal center) together provide a rigid asymmetric environment around this center, enabling high stereoselectivity in hydroformylations and hydrogenations of standard substrates.
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http://dx.doi.org/10.1021/ol401494x | DOI Listing |
Chemistry
June 2024
School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
The conceptual replacement of nitrogen with phosphorus in common organic functional groups unlocks new properties and reactivity. The phosphorus-containing analogues of triazenes are underexplored but offer great potential as flexible and small bite-angle ligands. This manuscript explores the synthesis and characterisation of a family of air-stable azophosphine-borane complexes, and their subsequent deprotection to the free azophosphines.
View Article and Find Full Text PDFJ Inorg Biochem
October 2022
School of Materials Science and Engineering, North University of China, Taiyuan 030051, PR China.
In order to develop an attractive generation of bulky oxadithiolate-bridged [FeFe]‑hydrogenase mimics with chelating diphosphines, two new series of asymmetrically diphosphine-substituted diiron model complexes [Fe(μ-Rodt)(CO)(κ-diphosphine)] (3-5) with bulky Phodt bridge and their reference counterparts (6-8) with common odt bridge were obtained from the MeNO-assisted substitutions of diiron hexacarbonyl precursors [Fe(μ-Rodt)(CO)] (Rodt = (SCHR)O, R = Ph (1) and H (2)) with different diphosphines such as (PhP)NBn (labelled PNP, Bn = benzyl), (PhPCH)NBn (PCNCP), and (PhPCH)CH (DPPP)), respectively. All the as-prepared complexes have been characterized by elemental analysis, IR plus NMR spectroscopies, and particularly by X-ray crystallography for 3-8. It is interesting to note that complexes 3 and 6 chelating by small bite-angle PNP diphosphine have the favorable dibasal isomer whereas analogues 4, 5 and 7, 8 chelating by flexible backbone PCNCP or DPPP ligands possess the main apical-basal isomer in solution or in the solid state.
View Article and Find Full Text PDFJ Mater Chem C Mater
March 2022
Department of Chemistry, University of Basel Mattenstrasse 24a, BPR 1096 4058-Basel Switzerland
The last decade has seen a surge of interest in the emissive behaviour of copper(i) coordination compounds, both neutral compounds that may have applications in organic light-emitting doides (OLEDs) and copper-based ionic transition metal complexes (Cu-iTMCs) with potential use in light-emitting electrochemical cells (LECs). One of the most exciting features of copper(i) coordination compounds is their possibility to exhibit thermally activated delayed fluorescence (TADF) in which the energy separation of the excited singlet (S) and excited triplet (T) states is very small, permitting intersystem crossing (ISC) and reverse intersystem crossing (RISC) to occur at room temperature without the requirement for the large spin-orbit coupling inferred by the presence of a heavy metal such as iridium. In this review, we focus mainly in Cu-iTMCs, and illustrate how the field of luminescent compounds and those exhibiting TADF has developed.
View Article and Find Full Text PDFInorg Chem
July 2021
Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstraße 4, 37077 Göttingen (Germany).
We prepared four new complexes, , and ,, from polyimido sulfur-centered ligands with Fe and Co amides. Their molecular structures were elucidated by single-crystal X-ray diffraction. Cobalt magnetic investigations and multiconfigurational calculations provided insight into magneto-structural correlations between the acute N,N' chelating bite angle and P-side arm donation.
View Article and Find Full Text PDFChemistry
April 2021
Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
A highly strained covalent organic cage compound was synthesized from hexahydroxy tribenzotriquinacene (TBTQ) and a meta-terphenyl-based diboronic acid with an additional benzoic acid substituent in 2'-position. Usually, a 120° bite angle in the unsubstituted ditopic linker favors the formation of a [4+6] cage assembly. Here, the introduction of the benzoic acid group is shown to lead to a perfectly preorganized circular hydrogen-bonding array in the cavity of a trigonal-bipyramidal [2+3] cage, which energetically overcompensates the additional strain energy caused by the larger mismatch in bite angles for the smaller assembly.
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