Crystalline phosphino-functionalized mesoionic olefins (p-MIOs)

• Published in: Dalton transactions : an international journal of inorganic chemistry 2022-05, Vol.51 (21), p.8217-8222
• Main Authors: Merschel, Arne, Vishnevskiy, Yury V, Neumann, Beate, Stammler, Hans-Georg, Ghadwal, Rajendra S
• Format: Article
• Language: English
• Subjects: Alkenes; Basicity; Crystal structure; Crystallinity; Gold compounds; Imidazole; Mathematical analysis; NMR spectroscopy; Reagents
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d2dt01314b

Phosphino-functionalized mesoionic olefins (p-MIOs), (iMIC)CHR (iMIC = PhC{N(Dipp)} 2 C(PPh 2 )C, Dipp = 2,6-iPr 2 C 6 H 3 ; R = H 4a or Ph 4b ), derived from a 1,3-imidazole-based mesoionic carbene (iMIC) are reported. The p-MIOs 4a (blue) and 4b (green) are crystalline solids and have been characterized by NMR spectroscopy and X-ray diffraction as well as DFT calculations. The calculated proton affinities of 4a (291.3 kcal mol −1 ) and 4b (288.1 kcal mol −1 ) support their remarkable basicity that exceeds that of classical NHCs. Treatment of 4a with (Me 2 S)AuCl (and AgOTf) affords the dinuclear gold compounds [( 4a )Au](X) 2 ( 5-X ) (X = Cl or OTf) with a short Au Au distance of 3.130(2) Å for 5-Cl . The reaction of 4a with the main-group reagent PhBCl 2 yields the boronium cation [( 4a )BPhCl]Cl ( 6 ). Phosphino-functionalized mesoionic olefins (p-MIOs), (iMIC)CHR (iMIC = PhC{N(Dipp)} 2 C(PPh 2 )C, Dipp = 2,6-iPr 2 C 6 H 3 ; R = H 4a or Ph 4b ), derived from a 1,3-imidazole-based mesoionic carbene (iMIC) are reported.