Hydridocopper Complexes Embedded in Iron Carbidocarbonyl Clusters: Synthesis, Reactivity, and Structure of [Fe4C(CO)12CuCl]2-, [Fe4C(CO)12Cu)(η2-BH4)]2-, [{Fe4C(CO)12Cu2(μ-H)}2]2-, and [{Fe4C(CO)12Cu2(μ-OiPr)}2]2-

The reaction of [Fe4C(CO)(12)(CuCl)(2)](2-) with NaBH4 yields sequentially [Fe4C(CO)(12)CuCl](2-) (1) and [Fe4C(CO)(12)Cu)(eta(2)-BH4)](2-) (2), depending on the Fe4Cu2:NaBH4 ratio. The reaction of [Fe4C(CO)(12)(CuNCMe)(2)] with NaBH4 yields [{Fe4C(CO)(12)Cu-2(mu-H)}(2)](2-) (3), which, upon precipitation with 2-propanol, forms [{Fe4C(CO)(12)Cu-2(mu-OiPr)}(2)](2-) (4). 1 and 2 are isostructural, with a CuX linearly bonded to the exposed carbide ligand of a butterfly [Fe4C(CO)(12)](2-) unit. 3 and 4 are also very similar, with the four copper atoms of two Fe4Cu2 octahedra connected by bridging hydrides (in 3) and bridging alkoxides (in 4). However, 3 and 4 are not isoelectronic, and in agreement with the unsaturation of 3, its Cu-Cu distance is much shorter.