RING-OPENING AND CLOSING IN (CO)N(L)MNI COMPLEXES WHERE L=S2CPCY3 OR DIPHOSPHINE - NOVEL COMPLEXES CONTAINING THE MN(MU-L)AUC6F5 ENTITY WHERE L=S2CPCY3 OR DPPM

The four-membered activated Mn-S-C-S ring in complexes containing S2CPCy3 chelate ligands are opened very easily when the complexes are treated with phosphites, isocyanides or diphosphines, to give complexes in which the S2CPCy3 entity is monodentate. In some cases, the resulting complexes undergo intramolecular displacement of CO by the uncoordinated sulfur with closing of the activated Mn-S-C-S ring. The uncoordinated sulfur in cationic complexes in which S2CPCy3 is monodentate, appears to be a poor nucleophile, and fails to bind a second metal to give four-electron bridges. Treatment of fac-[Mn(CO)3(dppm){SC(S)PCy3}]PF6 with [(tht)AuC6F5], causes opening of the chelate ring of the diphosphine dppm, and simultaneous closing of the ring of the S2CPCy3 ligand to give [(S2CPCy3)(CO)3Mn(mu-dppm)Au(C6F5)]PF6. However, the complex [(eta-5-C5H4-Me)(CO)2MnSC(PCy3)SAu(C6F5)], containing the first example of a eta-1(S), eta-1(S'), S2CPCy3 four-electron bridge between two different metals, can be prepared from [Mn(eta-5-C5H4Me)(CO)2(SC(S)PCy3)] and [Au(C6F5)(tht)].