From a Stable Dianion to a Stable Carbenoid

Abstract

International audienc

Phosphorus‐Bearing Lithium Compounds in Modern Synthesis

“…In addition, uranium carbene complexes formed in the reaction of 66 with UCl 4 have been used for the construction of delocalized arene-bridged diuranium single-molecule magnets [27]. Noteworthy in the field of phosphorus-stabilized carbenoids are the isolation of LiXC(Ph 2 PS) 2 (where X = Cl and I) species formed by oxidation of [C(Ph 2 PS) 2 ] 2− dianions with hexachloroethane [28] and iodine [29], respectively. The chlorine derivative showed a remarkable stability assigned to the coordination of the lithium cation to the two sulfur atoms of the molecule.…”

Structural and Spectroscopic Studies of the PCP-Bridged Heavy Chalcogen-Centered Monoanions [HC(PPh2E)(PPh2)]− (E = Se, Te) and [HC(PR2E)2]− (E = Se, Te, R = Ph; E = Se, R = iPr): Homoleptic Group 12 Complexes and One-Electron Oxidation of [HC(PR2Se)2]−

“…10 While the sulfur-containing dianion 4 has attracted considerable interest lately, primarily due to the exciting work of Le Floch et al, [8][9][10][11] 99.99%) and HgCl2 (Strem Chemicals, 99+%) were used as received. TMEDA·Li[HC(PPh2)2] was prepared by the reaction between H2C(PPh2)2 and MeLi in the presence of TMEDA in Et2O.…”

Geminal dianions stabilized by phosphonium substituents

“…Of interest is the reaction of Li 2 C[PPh 2 N(SiMe 3 )] 2 with (COD)RhCl and subsequent conversion with CO (Scheme 8) [43]. More advanced reactivity studies have been done on the methandiide Li 2 C(Ph 2 P S) 2 (25, Scheme 9) [25, 44,45]. Le Floch and co-workers reported on the reaction with hexachloroethane which gave partial chlorination to 26, the first lithium carbenoid that is stable at room temperature [44].…”

“…More advanced reactivity studies have been done on the methandiide Li 2 C(Ph 2 P S) 2 (25, Scheme 9) [25, 44,45]. Le Floch and co-workers reported on the reaction with hexachloroethane which gave partial chlorination to 26, the first lithium carbenoid that is stable at room temperature [44]. The crystal structure shows that efficient S, S-chelation of the Li + ion prevents Li· · ·Cl interaction and decomposition is only observed above 60 • C. The surprising stability of this carbenoid underscores the importance of its zwitterionic structure and the insignificance of a C· · ·Li interaction.…”