Isolation of Elusive Phosphinidene-Chlorotetrylenes: The Heavier Cyanogen Chloride Analogues |
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Authors: | Ekta Nag Maria Francis Sridhar Battuluri Bhavya Bini Sinu Dr Sudipta Roy |
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Institution: | Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Tirupati, 517507 India |
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Abstract: | The elusive phosphinidene-chlorotetrylenes, PGeCl] and PSiCl] have been stabilized by the hetero-bileptic cyclic alkyl(amino) carbene (cAAC), N-heterocyclic carbene (NHC) ligands, and isolated in the solid state at room temperature as the first neutral monomeric species of this class with the general formulae (L)P-ECl(L′) (E=Ge, 3 a – 3 c ; E=Si, 6 ; L=cAAC; L′=NHC). Compounds 3 a – 3 c have been synthesized by the reaction of cAAC-supported potassium phosphinidenides cAAC=PK(THF)x]n ( 1 a – 1 c ) with the adduct NHC:→GeCl2 ( 2 ). Similarly, compound 6 has been synthesized via reaction of 1 a with NHC:→SiCl2 adduct ( 4 ). Compounds 3 a – 3 c , and 6 have been structurally characterized by single-crystal X-ray diffraction, NMR spectroscopy and mass spectrometric analysis. DFT calculations revealed that the heteroatom P in 3 bears two lone pairs; the non-bonding pair with 67.8 % of s- and 32 % of p character, whereas the other lone pair is involved in π backdonation to the CcAAC-N π* of cAAC. The Ge atom in 3 contains a lone pair with 80 % of s character, and slightly involved in the π backdonation to CNHC. EDA-NOCV analyses showed that two charged doublet fragments {(cAAC)(NHC)}+, and {PGeCl}? prefer to form one covalent electron-sharing σ bond, one dative σ bond, one dative π bond, and a charge polarized weak π bond. The covalent electron-sharing σ bond contributes to the major stabilization energy to the total orbital interaction energy of 3 , enabling the first successful isolations of this class of compounds ( 3 , 6 ) in the laboratory. |
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Keywords: | cyclic alkyl(amino) carbene DFT and EDA-NOCV analyses N-heterocyclic carbene phosphinidene-chlorotetrylenes structure and bonding |
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