Abstract
The reaction of SeO 2 with Mn 2 (CO) 10 /KOH in methanol solution forms a trigonal bipyramid cluster anion [Se 2 Mn 3 (CO) 9 ] - (Ia). Cluster la can also be synthesized from the treatment of Se powder with Mn 2 (CO) 10 /KOH in 2:1 molar ratio in methanol solution. If Se is reacted with Mn 2 (CO) 10 /KOH in a molar ratio of 8:1, the deoxygenation occurs to produce a novel cluster [Se 8 C 2 Mn 2 (CO) 6 ] 2- (IIa). Cluster IIa can readily transform into a new octahedral cluster [Se 8 C 2 Mn 4 (CO) 12 ] 2- (IIIa) by further treatment with Mn 2 (CO) 10 /KOH in CH 2 C1 2 / MeOH solutions, and the use of a molar ratio of 1:1 of Se powder to Mn 2 (CO) 10 /KOH in methanol also can yield complex IIIa. In the sulfur-manganese system, the synthesis of the analogous complexes [S 2 Mn 3 (CO) 9 ] - (Ib), [S 8 C 2 Mn 2 (CO) 6 ] 2- (IIb), and [S 2 Mn 4 (CO) 12 ] 2- (IIIb) also can be accomplished from the reactions of S powder with Mn 2 (CO) 10 /KOH in similar fashions. Clusters Ia-IIIa and Ib-IIIb are fully characterized by spectroscopic methods or/and X-ray analyses. The novel clusters [E 8 C 2 Mn 2 (CO) 6 ] 2- (E = Se, IIa; E = S, IIb) each consist of two separate Mn(CO) 3 groups which are doubly bridged by two CE 4 fragments. Clusters Ia and Ib each display a trigonal bipyramid framework with two chalcogen atoms in the axial positions, while clusters IIIa and IIIb each exhibit an octahedral metal skeleton.