Octagallane (tBu3Si)6Ga8 and Its Reduction to (tBu3Si)6Ga82− − On the Existence of Isomeric Gallium Clusters

Abstract

Thermolysis of the trigallanyl radical R*4Ga3· in heptane at 60 °C leads to the dark blue octagallane R*6Ga8 (R* = supersilyl SitBu3), as well as the digallanyl radical R*3Ga2· and the tetrahedro‐tetragallane R*4Ga4. In addition, supersilyl radicals R*· are formed which stabilize themselves either by dimerization or by addition of hydrogen atoms. R*6Ga8 can be reduced in THF with NaC10H8 to the dark‐red octagallanediide Na2Ga8R*6·2THF. According to an X‐ray structure analysis of R*6Ga8 and R*6Ga82− one finds that the Ga atoms of four R*Ga moieties, together with two “naked” Ga atoms, occupy the corners of a distorted octahedron; the “naked” Ga atoms themselves are located, along with Ga atoms of two further R*Ga moieties, at the corners of a distorted square. The reduction of R*6Ga8 leads only to a negligible shortening of the Ga−Ga distances from 2.64 to 2.61 Å (mean values) in R*6Ga82−. Both the octagallanes possess Ga8 frameworks previously unknown for group 13 clusters. They are isomeric to the recently described Ga8 framework of the octagallane Tsi6Ga8 [Tsi = trisyl C(SiMe3)3]. Hence, not only boron but also the heavier group 13 atoms form isomeric clusters.

Synthesis and Structures of Polyhedral Hexa‐ and Octagallium Cluster Compounds

“…The latter is 58 pm longer than the equivalent distance in 17 . An additional structural relation with the metalloid [Ga 8 (R 2 ) 6 ] 0,2– 21 can be seen. Here, one edge of a Ga 6 octahedron is bridged by an additional Ga 2 (R 2 ) 2 unit.…”

Synthesis and Structures of Polyhedral Hexa‐ and Octagallium Cluster Compounds

“…The latter is 58 pm longer than the equivalent distance in 17 . An additional structural relation with the metalloid [Ga 8 (R 2 ) 6 ] 0,2– 21 can be seen. Here, one edge of a Ga 6 octahedron is bridged by an additional Ga 2 (R 2 ) 2 unit.…”

Synthesis and Structure of a Metal‐Rich Tetradecagallium Cluster with a Polyhedral Core

“…[Ga 9 R 6 ] − itself is derived formally from the addition of a Ga + to a bridging RGa‐GaR unit in [Ga 8 R 4 6 ] 2− . [ 26 ]…”

A decagallane(6) cluster Ga10[Si(CMe3)3]6 with an unprecedented structure

“…The pentagonal bipyramid is less flat (d GaGa = 344 pm) than that in 12. 7 15 can be explained as a closo-Ga 7 cluster with four silyl and two bridging RGa substituents.…”

Synthesis and Structures of Polyhedral Hexa‐ and Octagallium Cluster Compounds

“…The latter is 58 pm longer than the equivalent distance in 17 . An additional structural relation with the metalloid [Ga 8 (R 2 ) 6 ] 0,2– 21 can be seen. Here, one edge of a Ga 6 octahedron is bridged by an additional Ga 2 (R 2 ) 2 unit.…”

Synthesis and Structure of a Metal‐Rich Tetradecagallium Cluster with a Polyhedral Core

“…[Ga 9 R 6 ] − itself is derived formally from the addition of a Ga + to a bridging RGa‐GaR unit in [Ga 8 R 4 6 ] 2− . [ 26 ]…”

A decagallane(6) cluster Ga10[Si(CMe3)3]6 with an unprecedented structure

“…The pentagonal bipyramid is less flat (d GaGa = 344 pm) than that in 12. 7 15 can be explained as a closo-Ga 7 cluster with four silyl and two bridging RGa substituents.…”

Synthesis and Structures of Polyhedral Hexa‐ and Octagallium Cluster Compounds

“…The latter is 58 pm longer than the equivalent distance in 17 . An additional structural relation with the metalloid [Ga 8 (R 2 ) 6 ] 0,2– 21 can be seen. Here, one edge of a Ga 6 octahedron is bridged by an additional Ga 2 (R 2 ) 2 unit.…”

Synthesis and Structure of a Metal‐Rich Tetradecagallium Cluster with a Polyhedral Core

“…[Ga 9 R 6 ] − itself is derived formally from the addition of a Ga + to a bridging RGa‐GaR unit in [Ga 8 R 4 6 ] 2− . [ 26 ]…”

A decagallane(6) cluster Ga10[Si(CMe3)3]6 with an unprecedented structure

“…The pentagonal bipyramid is less flat (d GaGa = 344 pm) than that in 12. 7 15 can be explained as a closo-Ga 7 cluster with four silyl and two bridging RGa substituents.…”