Synthesis, crystal structures and magnetic properties of two iron (II) tris(pyridyl)phosphine selenides complexes

Structure of Tris[2-(4-pyridyl)ethyl]phosphine, Tris[2-(2-pyridyl)ethyl]phosphine, and Their Chalcogenides in Solution: Dipole Moments, IR Spectroscopy, and DFT Study

Tris(hetaryl)substituted phosphines and their chalcogenides are promising polydentate ligands for the design of metal complexes. An experimental and theoretical conformational analysis of tris[2-(4-pyridyl)ethyl]phosphine, tris[2-(2-pyridyl)ethyl]phosphine, and their chalcogenides was carried out by the methods of dipole moments, IR spectroscopy and DFT B3PW91/6-311++G(df,p) calculations. In solution, these compounds exist as an equilibrium of mainly non-eclipsed (synclinal or antiperiplanar) forms with a predominance of a symmetrical conformer having a gauche-orientation of the Csp3-Csp3 bonds of pyridylethyl substituents relative to the P=X bond (X = lone pair, O, S, Se) and a gauche-orientation of the pyridyl rings relative to the zigzag ethylene bridges. Regardless of the presence and nature of the chalcogen atom (oxygen, sulfur, or selenium) in the studied molecules with many axes of internal rotation, steric factors-the different position of the nitrogen atoms in the pyridyl rings and the configuration of ethylene bridges-determine the realization and spatial structure of preferred conformers.

The crystal structure of tris(6-methylpyridin-2-yl)phosphine oxide, C18H18N3OP

C18H18N3OP, monoclinic, P21/n (no. 14), a = 13.3987(17) Å, b = 8.7084(11) Å, c = 14.5063(18) Å, β = 95.849(2)° V = 1683.8(4) Å3, Z = 4, R gt (F) = 0.0423, wR ref (F 2) = 0.1311, T = 296(2) K.

The crystal structure of tris(6-methylpyridin-2-yl)phosphine selenide, C18H18N3PSe

C18H18N3PSe, monoclinic, P21/n (no. 14), a = 9.3064 (9) Å, b = 17.7311 (18) Å, c = 11.0556(11) Å, β = 105.317(1)°, V = 1759.5 Å3, Z = 4, Rgt (F) = 0.0365, wRref (F 2) = 0.0919, T = 296(2) K.

Organophosphorus chemistry based on elemental phosphorus: advances and horizons

The results of studies on the application of elemental phosphorus for the synthesis of important organophosphorus compounds are surveyed and summarized. Currently, this trend represents a synthetically, environmentally and technologically attractive alternative to classical organophosphorus chemistry based on toxic and corrosive phosphorus chlorides. Direct phosphination and phosphinylation of organic compounds with elemental phosphorus (discussed in the first part of the review) basically extend the range of available phosphines, phosphine chalcogenides and phosphinic acids and provides further development of their synthetic potential (discussed in the second part of the review). It is shown that the breakthrough in this area is largely due to the discovery of reactions of elemental phosphorus (white and red) with various electrophiles in superbasic suspensions and emulsions derived from alkali metal hydroxides and to the development of electrochemical, electrocatalytic and catalytic activation of white phosphorus.

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