1,3‐Dipolarophile Character of an Extremely Bulky Phosphaalkyne Mes*C≡P (Mes* = 2,4,6‐tBu₃C₆H₂) Leading to the Formation of 1,2,4‐Diazaphospholes with Unique Hydrogen Bonding Properties

Abstract

[a][ ‡]Keywords: Heterocycles / Phosphaalkynes / Cycloaddition / Hydrogen bonds / DFT calculations / X-ray crystallography 2-(2,4,6-Tri-tert-butylphenyl)-1-phosphaethyne was allowed to react with trimethylsilyldiazomethane derivatives to afford the corresponding 1,2,4-diazaphospholes via [2+3] cycloaddition followed by H/SiMe 3 migration, in spite of the steric encumbrance of the substrates. The aromatic character of 1,2,4-diazaphosphole is indicated by the NMR spectroscopic data and the X-ray structure analysis as well as by theoretical

Reactions of the Phosphinidene-Bridged Complexes [Fe2(η5-C5H5)2(μ-PR)(μ-CO)(CO)2] (R = Cy, Ph, 2,4,6-C6H2tBu3) with Diazoalkanes. Formation and Rearrangements of Phosphadiazadiene-Bridged Derivatives

“…Incidentally, this in agreement with the fact that the major isomer in the related complex 7e , which is not formed photochemically, but through a thermal reaction of 6 on the surface of alumina, exhibits the same arrangement of terminal ligands ( trans ) as its precursor 6 . Although the 1,3-shift responsible for the formation of 7f is not a common rearrangement, there are some precedents of related SiMe 3 shifts involving two N atoms or C and N atoms, and even 1,4-shifts between O and N atoms . Besides this, we should note the parallelism between the formation of the phosphide-iminoacyl complex 7f (reaction of the phosphinidene 1a with a diazoalkane followed by photochemically induced decarbonylation and 1,3-SiMe 3 shift) and the thermal formation of the mononuclear phosphine-iminoacyl complex [MoCp(CO) 2 { t Bu 2 PNHNC(CO 2 Et)}] from a terminal phosphide complex with ethyldiazoacetate followed by decarbonylation and 1,3-H shift at the presumed (undetected) diazoalkane adduct initially formed .…”