ChemInform Abstract: Steric Stabilization of Nucleophilic Carbenes.

Abstract

Steric Stabilization of Nucleophilic Carbenes.-The isolation of the new carbenes (IIa-d) is critically dependent on the bulk of the substituent R. The sterically most shielded carbene (IId) is a low-melting, colorless solid, which is stable under exclusion of air and moisture. In contrast, the attempted distillation of the carbenes (IIa-c) yields the dimers (IIIa-c). -(DENK, M. K.; THADANI, A.; HATANO, K.; LOUGH, A. J.; Angew. Chem., Int. Ed. Engl. 36 (1997) 23, 2607-2609 Dep. Chem., Erindale Coll., Univ. Toronto, Mississauga, Ont. L5L 1C6, Can.; EN)

Deoxygenation of chalcogen oxides EO2 (E = S, Se) with phosphaWittig reagents

“…With 146.41(19) and 147.21(17) pm the P1-O1/O2 atom distances are similar to those in the related, DMAP-stabilized phosphinidene dioxide [RPO2(DMAP)] (R = Ph, Mes; P-O = 147.4-147.9 pm) 75. The P1-O3 atom distance is considerably larger as a value of 169.03(13) pm is observed which is a comparably long P-O-P bridging bond (cf. [Ph-P(O)2]6; ⌀(P-O) = 160.1 pm)75 but still matches the covalent P-O single bond covalent radius of 174 pm 77.…”

“…54 1) are in agreement with known thiadiphosphiranes (cf. (Fc'-P)S; 57 P-P = 219.03 (12); P-S = 212.81(13)-213.48 (13) pm; Fc' = 2,5-bis(3,5-tBu2-C6H3)ferrocenyl). In general, the oxidation of diphosphenes with elemental sulfur (or selenium) is the most established route to synthesize threemembered P2E (E = S, Se) rings (Scheme 4).…”

“…From the perspective of a main-group chemist, SO2 binding [5][6][7][8][9][10][11][12][13][14][15] and activation, [16][17][18][19][20][21] conversion and/or reduction, [22][23][24][25][26][27][28] but also sorption [29][30][31][32][33] have been realized. Furthermore, the functionalization with SO2 building blocks has been achieved in various small organic molecules over time.…”