Sterically induced opening of a closo carbametallaborane: synthesis and characterisation of 1,2-Ph2-3-(η-C5Me5)-3,1,2-pseudocloso-RhC2B9H9

An unexpected cluster opening upon the formation of electronically unsaturated η3-(cyclooctenyl)metallacarboranes of rhodium(III) and iridium(III) with sterically reduced [(PhCH2)2C2B9H9]2− ligand

“…The average separations between the cage carbon atoms C(1)Á Á ÁC(2) and the contracted M(3)Á Á ÁB(6) interatomic distance for two independent molecules of 4 are 2.22 and 3.12 Å; the corresponding separations in 5 are 2.32 and 3.05 Å, respectively (Table 1). Thus, the observed structural cagedeformed characteristics of 4 are comparable with those of semipseudocloso-metallacarboranes [2,3], and those of complex 5 fit better with pseudocloso-shaped systems [1,3].…”

“…Twelve-vertex pseudocloso- [1] and semipseudocloso-metallacarboranes [2] of a unique open-cage architecture with broken or significantly strained polyhedral carbon-carbon connectivity have only lately been recognized as an important new subgroup of metallacarborane clusters, which geometrically lie intermediate between metallacarboranes of closo and hypercloso/isocloso structures on the Wade-Williams matrix [3]. These compounds due to rich structural chemistry as well as their potentiality for in-depth mechanistic study of the low-temperature polyhedral isomerization processes of icosahedral metallacarboranes have received increasing attention in recent years [4].…”

Sterically Encumbered, Charge-Compensated Metallacarboranes. Synthesis and Structures of Ruthenium Pentamethylcyclopentadienyl Derivatives

“…The 11 B{ 1 H} spectrum displays eight resonances in the range from 27.2 to −16.4 ppm, in the ratio (high to low frequency) 1:1:1:1:1:2:1:1. Not only is this a significantly larger chemical shift range than that found for the closo compounds 1 − 4 , but also the average shift, <δ( 11 B)>, is +2.60 ppm, substantially to higher frequency and characteristic of a pseudocloso structure. ,,− Note that although <δ( 11 B)> for 5 lies ca. 3−4 ppm to lower frequency than that previously reported for pseudocloso (η 6 -arene)RuPh 2 C 2 B 9 H 9 compounds, the difference can be fully accounted for by correcting for the differences in polyene and carborane, since, typically, <δ( 11 B)> for 1 is −12.6 ppm while <δ( 11 B)> for 1-Ph-3-(cym)-3,1,2- closo -RuC 2 B 9 H 10 is −8.0 ppm 13b.…”

Structure of 7,8-Ph2-10-endo-PPh3Hg-7,8-nido-C2B9H9 methylene chloride solvate

“…Degassed CH2C12 (15 cm 3) was added to a solid mixture of T1217,8-Ph2-7,8-nido-C2BgHg] (0.349 g, 0.504mmol) (Lewis & Welch, 1992) and [PPh3HgCI2]2 (0.269 g, 0.252 mmol) (Evans, Mann, Peiser & Purdie, 1940) in a foil-covered vessel at 77 K. The mixture was warmed to room temperature with stirring, and then filtered to afford a pale yellow solution. The solution was concentrated and excess hexane added, yielding a white flocculate and a green oil.…”