Reaction of [Cp-2(CO)(3)Mo-2(mu-eta(2)-P-2)(PPh2)](-) with the cumulenes 3-ClC6H4NCO, PhNCS, and CS2 and with Michael acceptors: Synthesis and reactivity of [Cp-2(CO)(3)Mo-2(mu-eta(3)-Ph2PC(H)SP2S)], a complex containing an unusual CSP2S five-membered ring

Deprotonation of the complex [Cp-2(CO)(3)Mo-2(mu-eta(2)-P-2)(PPh2H)] (1) yi elds the anion [Cp-2(CO)(3)Mo-2(mu-eta(2)-P-2)(PPh2)](-) (2). Reaction of 2 with cumulenes such as 3-ClC6H4NCO and PhNCS leads, after reprotonation, t o the simple addition products [Cp-2(CO)(3)Mo-2(mu-eta(2)-P-2){PPh2C(=X)NHR }] (R = 3-ClPh, X = O, 4a; R = Ph, X = S, 4b). Reaction of 2 with the Micha el acceptors H2C=C(H)R gives the related products [Cp-2(CO)(3)Mo-2(mu-eta(2 )-P-2)(PPh2C2H4R)] (R = COOMe, 5a; R = CN, 5b; R = COMe, 5c). In contrast, reaction of 2 with CS2 followed by HBF4 yields the complex [Cp-2(CO)(3)Mo-2 (i)(mu-eta(3)-Ph2PC(H)SP2S)] (3), which has an unprecedented bridging ligan d containing a CSP2S five-membered ring. Reaction of 3 with (BuLi)-Bu-t fol lowed by MeI yields [Cp-2(CO)(3)Mo-2(mu-eta(2)-P-2){PPh2C(S)SMe}] (6), in w hich ring scission and re-formation of the tetrahedral Mo2P2 core present i n complex 1 has taken place. Reaction of 3 with metal carbonyls can also le ad to re-formation of the Mo2P2 moiety. The crystal structures of five of t he new complexes have been determined.