ε⁶-Phosphinine-and ε⁶-1,3-Diphosphinine Iron Complexes

Abstract

Efficient synthetic routes are described, leading to novel n^-phosphinine-(1) and n, 6 -l,3-diphosphinine (4,5) iron(0) complexes. 1 is a catalyst for pyridine formation by a [2+2+2]-cyclic addition reaction of nitriles and alkynes and 4 is a useful source of unsaturated free four and six membered organophosphorus rings.

o-, m-, and p-Diphosphabenzenes and Their P2(C−H)4 Valence Isomers. An Ab Initio Theoretical Study

“…This latter supposition is definitely ruled out by the present study, which suggests that the reason the 1,3 or 1,4 isomers are preferentially formed might rather lie in the synthetic methods that are used to generate diphosphinines. Indeed, 1,3 isomers ( 2 ) are always formed by ring expansion of four-membered rings in which the phosphorus atoms are already in the 1,3 position, , while the 1,4 isomer ( 3 ) is obtained either from an 1,4-bicyclooctatriene 10 or a dichloro-1,4-diphosphabicycloheptadiene, two compounds in which the phosphorus atoms are right at the outset in the 1,4 position. Thus, it is our feeling that the synthetic methods that have been used to date favor the formation of 1,3 or 1,4 isomers and that the preparation of various derivatives of the 1,2 isomer should be feasible.…”

“…Assuming the hexagonal planar conformations to be the most stable, three isomers of diphosphinine ( 1 − 3 in Figure ) can be a priori anticipated to be observable. Indeed, 1,3-diphosphinines ( 2 ) are rather stable and have been prepared in the coordination sphere of iron. , On the other hand, only one 1,4-diphosphinine ( 3 ) is known, bearing four CF 3 substituents or photoisomerize .…”

First X-ray Crystal Study and DFT Calculations of Anionic λ4-Phosphinines

“…Most of the complexes are found in which the ligand is bound to the metal center in a η 1 -fashion (coordination through the lone pair) . There are also a significant number of η 6 -complexes. − In these complexes, the lone pair at phosphorus is still available for η 1 -coordination, and in fact this “double” coordination, in which the ligand acts as an eight-electron donor, has been observed in a few cases. , On the other hand, very few η 5 -phosphacyclohexadienyl complexes have been reported to date. , In these complexes, only five of the six atoms of the phosphinine are bound to the metal center. Their synthesis usually involves nucleophilic attack at the electrophilic phosphorus center of a η 6 -complex followed by a trapping reaction with an electrophile (Scheme ).…”

Complexes of Azaphospholes: Synthesis and Structure of Pentacarbonyl-(η1)-2-phosphaindolizine)chromium(0), -molybdenum(0), and -tungsten(0)

“…In 7g the P c triplet becomes a double triplet by In the reaction of 1f with tricarbonyl(cycloheptatriene)-molybdenum(0), initial formation of probably 6f was obIn view of the existence of σ-and π-coordination modes in carbonyl complexes of phosphabenzene [16] [20] [21] , phos-served by a singlet at δ 31 P ϭ 178.9 and a line form of the proton-coupled phosphorus multiplet resembling rather a phole anions [1] [2] , and π-excess heterocycles such as pyrrole [3] [4] [5] , we tried to obtain η 5 -2-phosphaindolizine π-fac-L 3 Mo(CO) 3 than a trans-L 2 Mo(CO) 4 coupling pattern. However, this complex proved to be unstable in extractive complexes.…”