Showing papers by "Sayan Dutta published in 2017"
TL;DR: This study shows an unprecedented example of two conformational isomers with different Ccarbene -element bonds, isolated from the direct reaction between cAAC and phosphorus trichloride, which were further studied by theoretical calculations.
Abstract: The cyclic alkyl(amino) carbene (cAAC) bonded chlorophosphinidene (cAAC)P-Cl (2/2´) was isolated from the direct reaction between cAAC and phosphorus trichloride (PCl3). Compound 2/2´ has been characterized by NMR and mass spectrometry. 31P NMR investigations [~160 ppm (major) and ~130 ppm (minor)] structural determination reveal that there are two different P environments of P-Cl unit. X-ray single crystal determination suggests a co-crystallization of two conformational isomers of (cAAC)P-Cl (2/2´); the major compound possessing a cAAC-PCl unit with CcAAC-P 1.75 A. This C-P bond length is very close to that of (NHC)2P2 [NHC = N-heterocyclic carbene]. The residual density can be interpreted as a conformational isomer with a shorter CcAAC-P bond similar to non-conjugated phosphaalkene [R-P=CR2]. Our study represents an unprecedented example of two conformational isomers with different Ccarbene-element bonds. Additionally, Br (3c/3c´), I (4c/4c´) and H (5c/5c´) analogues [(Me2-cAAC)P-X; X = Br (3), I (4), H (5)] of 2c/2c´[(Me2-cAAC)P-Cl] were also synthesized and characterized by NMR spectroscopy suggesting similar equilibrium in solution. The unique property of cAAC and the required electronegativity of the X (X = Cl, Br, I and H) atom play a crucial role for the existence of the two isomers which are further studied by theoretical calculations.
32 citations
TL;DR: Two cyclic (alkyl)(amino)carbene (cAAC) stabilized mononuclear neutral radicals of aluminum have been synthesized and were confirmed by EPR measurements to have the spin located on the carbene carbon of one of the cAAC ligands.
32 citations