[Co 4 (μ 3 ‐As) 3 )(μ 3 ,η 3 ‐As 3 )(PPh 3 ) 4 ], a Product of the Reaction of [CoCl 2 (PPh 3 ) 2 ] with PhAs(SiMe 3 ) 2

A ring containing three As atoms (white) is linked in a novel fashion to a tetrahedron of four Co atoms (black) in the Co 4 As 6 core of the title cluster compound. The other As atoms cap the remaining three faces of the tetrahedron. (The four PPh 3 groups bonded to the Co atoms are omitted).