Bis(μ 4 -adamantane-1,3-di-carboxyl-ato-1κ O 1 :2κ O 1' :3κ O 3 :4κ O 3' )octa-carbonyl-1κ 2 C ,2κ 2 C ,3κ 2 C ,4κ 2 C -tetra-kis-[tris-(4-methyl-phen-yl)phosphane]-1κ P ,2κ P ,3κ P ,4κ P -tetra-osmium(I)(2 Os - Os ).

The title complex, [{Os 2 (CO) 4 (C 21 H 21 P) 2 } 2 (C 12 H 14 O 4 ) 2 ], is a centrosymmetric mol-ecular loop consisting of two Os-Os sawhorse units linked by two adamantane di-carboxyl-ato bridges. It was synthesized by the microwave-mediated reaction between Os 3 (CO) 12 and adamantane-1,3-di-carb-oxy-lic acid. In contrast to the related complex [{Os 2 (CO) 6 } 2 (μ 4 -adamantane-1,3-di-acetate) 2 ], the metal-metal axes within each mol-ecule are oriented parallel rather than perpendicular to one another. The crystal structure exhibits cavities that contain residual electron density peaks, but it was not possible to unambiguously identify the solvent therein. The contribution of the disordered solvent mol-ecules to the scattering was removed using the SQUEEZE (Spek (2015 ▸). Acta Cryst . C 71 , 9-18) routine in PLATON [Spek (2020 ▸). Acta Cryst . E 76 , 1-11]. These solvent mol-ecules are not considered in the given chemical formula and other crystal data.