Dicobaltoctacarbonyl, [Co 2 (CO) 8 ], has always been the metal complex of choice in the widely used Pauson ± Khand reaction for the formation of bicyclo[3.3.0]octenones by the cyclocarbonylation of an alkene and an alkyne (Scheme 1). [1] Alternative sources of zero valent cobalt, namely [(indenyl)Co(cod)] and [Co(acac) 2 ]/NaBH 4 , and cobalt carbonyl clusters, such as [Co 4 (CO) 12 ], [Co 3 (CO) 9 (m 3 -CH)], and [Co 4 -(CO) 11 P(OPh) 3 ], have also been developed but are less O CO + Co catalyst Scheme 1. Cobalt catalysis in the Pauson ± Khand reaction. Co catalyst: [Co 2 (CO) 8 ] with or without additive (phosphite, phosphane, cyclohexylamine (CyNH 2 ), phosphane sulfide, 1,2-dimethoxyethane (DME), water), [Co 4 (CO) 12 ], [Co 4 (CO) 11 P(OPh) 3 ], [Co 3 (CO) 9 (m 3 -CH)], [(indenyl)Co-(cod)], [Co(acac) 2 ]/NaBH 4 . cod cycloocta-1,4-diene; acac acetylacetonate.
mixture of pyridine (4.55 g) and water (0.147 g). Then ethylenediamine (1.038 g) was added and stirred until the mixture became a clear solution. Finally boric acid (0.18 g) and 40 % HF (0.062 g) were added to the obtained solution (pH 11.12), which was then heated at 1708C for 10 days in a 23 mL Teflon-lined Parr autoclave. The product (yield 0.206 g), consisting of a white powder and thin platelike single crystals, was collected, washed with deionized water and ethanol, and dried at room temperature. The Ge content was confirmed by energy-dispersive spectroscopy (EDS).