Chalcogen-Centered Spirocyclic Mixed-Metal Carbonyl Complexes:  Synthesis and Molecular Structures of (CO)<sub>8</sub>(μ-PCy<sub>2</sub>)Re<sub>2</sub>(μ<sub>4</sub>-E)Fe<sub>2</sub>(μ-ER)(CO)<sub>6</sub> and [(CO)<sub>8</sub>(μ-PCy<sub>2</sub>)Re<sub>2</sub>(μ<sub>4</sub>-E)Fe<sub>2</sub>(CO)<sub>6</sub>]<sub>2</sub>(μ<sub>4</sub>-E<sub>2</sub>) (E = S, Se, Te; R = Organic Residue)

When NEt<sub>4</sub>[Re<sub>2</sub>(μ-PCy<sub>2</sub>)(CO)<sub>8</sub>] (<b>1</b>) was reacted with Fe<sub>2</sub>(μ-E<sub>2</sub>)(CO)<sub>6</sub> (E = S, Se, Te) in THF, the salts NEt<sub>4</sub>[(CO)<sub>8</sub>(μ-PCy<sub>2</sub>)Re<sub>2</sub>(μ<sub>4</sub>-E)Fe<sub>2</sub>(μ-E)(CO)<sub>6</sub>] (E = S (<b>2a</b>), Se (<b>2b</b>), Te (<b>2c</b>)) were formed. Their spirocyclic anions were trapped with MeI, giving the spirocyclic complexes (CO)<sub>8</sub>(μ-PCy<sub>2</sub>)Re<sub>2</sub>(μ<sub>4</sub>-E)Fe<sub>2</sub>(μ-EMe)(CO)<sub>6</sub> (E = S (<b>3a</b>), Se (<b>3b</b>), Te (<b>3c</b>)). Their molecular structures were confirmed by single-crystal X-ray analysis. The anions of <b>2a</b>−<b>c </b>are sensitive to oxidation. On crystallization in the presence of oxygen the corresponding dichalcogenides [(CO)<sub>8</sub>(μ-PCy<sub>2</sub>)Re<sub>2</sub>(μ<sub>4</sub>-E)Fe<sub>2</sub>(CO)<sub>6</sub>]<sub>2</sub>(μ<sub>4</sub>-E<sub>2</sub>) (E = S (<b>4a</b>), Se (<b>4b</b>), Te (<b>4c</b>)) were obtained in good yield. Their molecular structures were confirmed by single-crystal X-ray analysis. <b>2a</b> was also trapped with CF<sub>3</sub>COOH, giving (CO)<sub>8</sub>(μ-PCy<sub>2</sub>)Re<sub>2</sub>(μ-S<sub>4</sub>)Fe<sub>2</sub>(μ-SH)(CO)<sub>6</sub> (<b>5</b>). The latter can be expanded by SH oxidative addition of its μ-SH function to Os<sub>3</sub>(CO)<sub>11</sub>(NCMe), giving the mixed-metal carbonyl complex (CO)<sub>8</sub>(μ-PCy<sub>2</sub>)Re<sub>2</sub>(μ<sub>4</sub>-S)Fe<sub>2</sub>(CO)<sub>6</sub>(μ<sub>3</sub>-S)Os<sub>3</sub>(μ-H)(CO)<sub>11</sub> (<b>6</b>). The framework of <b>6</b> could be derived from X-ray diffraction data. However, these data were insufficient for complete solution of the molecular structure, but spectroscopic data and elemental analysis of <b>6</b> are in accordance with the proposed molecular structure.