Tetrametal clusters

The most common geometrical arrangement of metals in tetrametal clusters is the tetrahedron, a polyhedron which represents the simplest case of a 3-dimensional cluster. It is convenient to start the discussion by considering the basic structures of the dodecacarbonyls and then to consider the effects produced by increasing and decreasing the number of carbonyl groups around the tetrahedral unit of metals. 

The reaction of dichlorobis(triphenylphosphine)platinum(II) with Na[Co(CO)4] gives only the tetrametal cluster, Pt2Co2(PPh3)(CO)8, in a low yield.3 The corresponding trimetal cluster, PtCo2(PPh3)(CO)8,4 is obtained... 

B. Metal-Core Rearrangements in Several Tetrametal Clusters... 

Pentametal boride clusters feature far less frequently in the Uterature than do tetrametal or hexametal species, and systematic expansion of an M4B to M5B or M4M B cage is difficult reaction pathways tend to continue through to the species in which the boron atom is fully encapsulated.During the formation of [Fe4Rh2(CO)i6B], Fehlner had observed the formation of an intermediate species proposed as an Fe4RhB cluster, but it eluded isolation. 

Ting-Wah Chu C, Yip-Kwai Lo F, Dahl LF (1982) Synthesis and stereochemical analysis of the [Fe4(NO)4 (.Mu.3-S)4]N Series (N=0, —1) which possesses a Cubanelike Fe4S4 core direct evidence for the antibonding tetrametal character of the unpaired electron upon a one-electron reduction of a completely bonding tetrahedral metal cluster. J Am Chem Soc 104 3409-3422... 

The crystal structures of many organolithium compounds have been determined. Phenyllithium has been crystallized as an ether solvate. The structure is tetrametic, with lithium and carbon atoms at alternating comers of a strongly distorted cube. Each carbon is 2.33 A from the three neighboring lithium atoms. An ether molecule is coordinated to each lithium atom. Figure 7.2a shows the Li-C cluster, and Fig. 7.2b shows the complete array of atoms, except for hydrogen. Section 7.1 of Part A provides additional information on the stmcture of organolithium compoimds. 

McGinnis RN, Ryan TR, McCarley RE (1978) Reactions of activated quadruply bonded molybdenum dimers. Formation of new rectangular clusters containing the tetrametal analog of cyclobutadiyne. J Am Chem Soc 100 7900-7902... 

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