alpha-Sulfinyl Transition Metal Bond. 1. Naked alpha-Sulfenyl Anions and their Reactivity with Metal Carbonyls: Synthesis of Metal-Carbon Bonded alpha-Sulfenyls and alpha-Sulfenylcarbenes

Deprotonation of ArSOCH3 [Ar = C6H5,1; Ar = 4-MeC6H4, 2] with KH in THF in the presence of 18-crown-6 and Kryptofix-2,2,2 led to the isolation of the respective ion-contact and ionseparated pairs: [ArS(CH2)O⋯K(18-crown-6)] [Ar = C6H5, 3; Ar = 4-MeC6H4,4]; [ArS(CH2)O⋯K-(kryptofix-2,2,2)] [Ar = C6H5, 5; Ar = 4-MeC6H4,6]. The complexation of the potassium cation in both 4 and 6 causes the complete racemization of the α-sulfinyl anion. The structures of 3 and 5 have been determined with an X-ray analysis. The reaction of 3 and 4 with [Cr(CO)5-(THF)] led to the formation of α-sulfinyl carbonylmetalates containing a CrC σ bond, in [ArS(O)CH2Cr(CO)5]−[K(18-crown-6)]+[Ar = C6H5, 7; Ar = 4-MeC6H4, 8]. The high nucleophilicity of 3 is demonstrated in the reaction with a weakly electrophilic CO in [Cr(CO)6]. The reaction gives an unprecedented metallacarbene–sulfinyl anion complex, [{(CO)5CrC(O)CHS(O)Ph}⋯{K(18-crown-6)}2], 10, in which the carbene sulfoxide fragments migrate to a carbon monoxide, forming an α-sulfinylcarbene metallacycle, [formula omitted]⋯{K(18-crown-6)}2], 11. Exhaustive silylation of the peripheral oxygens of 11 led to the corresponding silylated form 12. Crystallographic details: 3 is monoclinic, space group P21, with a = 9.025(1) Å, b = 15.799(2) Å, c = 8.579(1) Å, α = γ = 90°, β = 107.76(1)°, Z = 2, and R = 0.040; 5 is triclinic, space group P1̅, with a = 10.713(1) Å, b = 10.825(1) Å, c = 14.877(1) Å,α = 112.07(1)°, β = 112.83(1)°, γ = 80.39(1)°, Z = 2, and R = 0.067; 11 is triclinic, space group P1̅, with a = 15.251(4) Å, b = 16.774(2) Å, c = 11.833(2) Å, α = 109.75(1)° β = 110.30(2)°, γ = 85.94(1)°, Z = 2, and R = 0.049.