Reaction of [Cp2(CO)3Mo2(μ-η2-P2)(PPh2)]- with the Cumulenes 3-ClC6H4NCO, PhNCS, and CS2 and with Michael Acceptors: Synthesis and Reactivity of [Cp2(CO)3Mo2(μ-η3-Ph2PC(H)SP2S)], a Complex Containing an Unusual CSP2S Five-Membered Ring

Deprotonation of the complex [Cp 2 (CO) 3 Mo 2 (μ-η 2 -P 2 )(PPh 2 H)] ( 1 ) yields the anion [Cp 2 (CO) 3 Mo 2 (μ-η 2 -P 2 )(PPh 2 )] - ( 2 ). Reaction of 2 with cumulenes such as 3-ClC 6 H 4 NCO and PhNCS leads, after reprotonation, to the simple addition products [Cp 2 (CO) 3 Mo 2 (μ-η 2 -P 2 ){PPh 2 C( X)NHR}] (R = 3-ClPh, X = O, 4a; R = Ph, X = S, 4b ). Reaction of 2 with the Michael acceptors H 2 C C(H)R gives the related products [Cp 2 (CO) 3 Mo 2 (μ-η 2 -P 2 )(PPh 2 C 2 H 4 R)] (R = COOMe, 5a; R = CN, 5b; R = COMe, 5c ). In contrast, reaction of 2 with CS 2 followed by HBF 4 yields the complex [Cp 2 (CO) 3 Mo 2 (μ-η 3 -Ph 2 PC(H)SP 2 S)] ( 3 ), which has an unprecedented bridging ligand containing a CSP 2 S five-membered ring. Reaction of 3 with t BuLi followed by MeI yields [Cp 2 (CO) 3 Mo 2 (μ-η 2 -P 2 ){PPh 2 C(S)SMe}] ( 6 ), in which ring scission and re-formation of the tetrahedral Mo 2 P 2 core present in complex 1 has taken place. Reaction of 3 with metal carbonyls can also lead to re-formation of the Mo 2 P 2 moiety. The crystal structures of five of the new complexes have been determined.