“…The reaction is sensitive to the molar ratio of the reactants: When Na 2 [Cr 2 (CO) 10 ] and SnCl 2 are used in a 3:1 ratio, the star-type compound [Sn{Cr(CO) 5 } 3 ] 2Ϫ is the main product. [21] With Na 2 [Mo 2 (CO) 10 ] or Na 2 [W 2 (CO) 10 ] used in the same molar ratio, mixtures of products are obtained which do not contain any 5 or 6, as judged from their IR absorptions. When a ratio of 1:1 is used, the isolated yield of 4 (as its Ph 4 P salt) is approximately 10%, along with other products in the reaction mixture.…”