Symmetrical and Mixed Tris(acyl)phosphines: Synthesis, Oxidation and Photochemistry.

Invited for the cover of this issue are the groups of M. Haas, G. Gescheidt and H.

Symmetrical and Mixed Tris(acyl)phosphines: Synthesis, Oxidation and Photochemistry.

Herein, we present a convenient synthesis for symmetrical and mixed substituted tris(acyl)phosphines (TAPs) starting from red phosphorus. All TAPs exhibit a phosphaalkene-acylphosphine equilibrium, which was investigated in detail by variable-temperature (VT) NMR spectroscopy supported by density-functional theory (DFT) calculations. Depending on the substituents, two phosphaalkene derivatives and ten acylphosphine derivatives could be isolated.

Bis(acyl)phosphide - Ambidentate Ligands for the Synthesis of Group 14 and 15 Main Group Element Compounds.

The reactivity of the bis(acyl)phosphide ion [P(COR) ] (BAP , R=Ph, Mes) with silicon halides SiX (X=Cl, Br) and pnictogen chlorides ECl (E=As, Sb and Bi) was investigated. The reaction with SiX leads to the hexacoordinate silanes SiX (BAP) in which BAP is coordinated in the chelating κ -O,O' mode, analogously to acac . Unexpectedly, the coordination behaviour of BAP differs from the one of acac in the interpnictogen compounds E(BAP) (E=As, Sb) in which the formation of E-P bonds is favoured over κ -O,O' chelation via the oxygen centres.

Transient Dipnictyl Analogues of Acrylamides, R-E=E'-CONR , and a Related Diphosphadigalletane from Na[OCP] and (R N) ECl (E, E'=P, As, Ga).

The reaction of Na[OCP] with (R N) ECl (E=P or As; R=alkyl) granted direct access to transient amine-substituted diphospha- and arsaphospha-acrylamide analogues, (R N)E=P(CONR ) 1. Their facile formation allowed for a comprehensive reactivity study. Dimerization yielded the four-membered rings (R N) E P (CONR ) , whereas in the presence of excess Na[OCP], a stepwise [2+2] cycloaddition occured, leading to the sodium salts of carboxotripnictides [(R N)EP CO(CONR )] .

Synthesis of PCO and PCO via NHC-mediated coupling of the phosphaethynolate anion.

The reaction of the chloroimidazolium chloride salt, [NHC-Cl][Cl], NHC = C{N(2,6-PrCH)CH} (1) with two equivalents of sodium phosphaethynolate, Na[OCP]·(dioxane), results in the formation of NHC-{cyclo-(CO)-P-C(O)} (2) and NHC-P-C(O)-NHC (3). Notably, in the presence of free NHC ligand, compound 2 converts to compound 3via extrusion of CO at elevated temperatures. The nature of the bonding in these complexes was probed computationally and spectroscopically.

Tris(2-pyridyl)phosphine as a versatile ligand for pnictogen acceptors.

We report cationic complexes of arsenic and antimony with the tris(2-pyridyl)phosphine ligand. Chloride ion abstraction from AsCl using TMSOTf in the presence of the ligand gives [P(Pyr)As][OTf], in which the trication adopts a C symmetric cage structure. The reaction proceeds via the intermediate [P(Pyr)AsCl][OTf], which undergoes chloride exchange to give [P(Pyr)As][OTf] and [P(Pyr)AsCl][OTf].