Heteroatomic Deltahedral Clusters:  Synthesis and Structures of closo-[Bi₃Ni₄(CO)₆]^3-, closo-[Bi₄Ni₄(CO)₆]^2-, the Open Cluster [Bi₃Ni₆(CO)₉]^3-, and the Intermetalloid closo-[Ni_x@{Bi₆Ni₆(CO)₈}]^4-

Reactions of ethylenediamine solutions of K₄Bi₅ with Ni(PPh₃)₂(CO)₂ yielded four novel hetero-atomic Bi/Ni deltahedral clusters. Three of them, the 7-atom pentagonal bipyramidal [Bi₃Ni₄(CO)₆]^3-, the 8-atom dodecahedral [Bi₄Ni₄(CO)₆]^2-, and the Ni-centered or empty 12-atom icosahedral [Ni_x@{Bi₆Ni₆(CO)₈}]^4-, are closo-species according to both electron count and shape. The centered icosahedral cluster resembles packing in intermetallic compounds and belongs to the emerging class of intermetalloid clusters. The shape of the fourth cluster, [Bi₃Ni₆(CO)₉]^3-, can be derived from the icosahedral Ni-centered [Ni@{Bi₆Ni₆(CO)₈}]^4- by removal of three Bi- and one Ni-atoms of two neighboring triangular faces. The clusters were structurally characterized by single-crystal X-ray diffraction in compounds with potassium cations sequestered by 2,2,2-crypt or 18-crown-6 ether. They were also characterized in solution by electrospray mass spectrometry.