3H-Benzophosphepine Complexes:  Versatile Phosphinidene Precursors

Abstract

The synthesis of a variety of benzophosphepine complexes [R = Ph, t-Bu, Me; ML(n )()= W(CO)(5), Mo(CO)(5), Cr(CO)(5), Mn(CO)(2)Cp] by two successive hydrophosphinations of 1,2-diethynylbenzene is discussed in detail. The first hydrophosphination step proceeds at ambient temperature without additional promoters, and subsequent addition of base allows full conversion to benzophosphepines. Novel benzeno-1,4-diphosphinanes were isolated as side products. The benzophosphepine complexes themselves serve as convenient phosphinidene precursors at elevated, substituent-dependent temperatures (>55 degrees C). Kinetic and computational analyses support the proposal that the phosphepine-phosphanorcaradiene isomerization is the rate-determining step. In the absence of substrate, addition of the transient phosphinidene to another benzophosphepine molecule is observed, and addition to 1,2-diethynylbenzene furnishes a delicate bidentate diphosphirene complex.

Assessment of the Electronic Properties of P ligands Stemming from Secondary Phosphine Oxides

“…Some phosphinous acid‐metal carbonyls had been described 1. 2 Among them, only tungsten‐ or molybdenum‐pentacarbonyl complexes25–27 belong to known scales that correlate to the Tolman’s parameter. From these, we could estimate the TEP of four phosphinous acids (Table 1, entries 1–4).…”

π-Extended Phosphepines: Redox and Optically Active P-Heterocycles with Nonplanar Framework

“…Before using the -extended phosphepines as active material in devices, we investigated their thermal stability because some phosphepines are known to be rather unstable. 17 An intramolecular ring closure leading to the formation of phosphanorcaradiene and to a release of phosphinidene can take place. However, this transformation is usually blocked by the introduction of αt Bu substituents, 18 or by benzannellation.…”

“…However, this transformation is usually blocked by the introduction of αt Bu substituents, 18 or by benzannellation. 17 The thermogravimetric analyses (TGA) measurements performed on compound 6 show a decomposition temperature at 10% weight loss (Td10) of 400 °C ( Figure S20). Furthermore, differential scanning calorimetry (DSC) measurements show no melting point.…”

A novel synthesis of stable 3H-pyrrolizine fused diazaborepin

“…[1][2][3][4][5][6] Heteropines incorporated heteroatoms such as B,7,8 Al, 9 Ga, 10,11 Si, 12,13 Ge, 14 Sn, 15 P, 16,17 As, 18 Bi, 18 and Se. 14 B-heteropine, denoted as borepin with a heterocyclic ring containing only boron and carbon atoms was used by Letsinger et al 19 in 1955.…”