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The title compound consists of a neutral [Co(C2H)(C3H9P)4] unit, with the ligands arranged in a distorted trigonal bipyramidal configuration, retaining threefold axial symmetry. The C
CH unit occupies an axial position, with a C
C bond length of 1.185 (6) Å. This compound represents the first structurally characterized example of a cobalt(I)–ethynyl complex.
![[triple bond]](/logos/entities/z-tbnd_rmgif.gif)
![[triple bond]](/logos/entities/z-tbnd_rmgif.gif)