Synthesis and structure of (boratabenzene)rhodacarborane (η-7,8-C2B9H11)Rh(η-C5H5BMe)

Loginov, Dmitry A.; Starikova, Z. A.; Petrovskii, P. V.; Kudinov, Alexander R.

doi:10.1007/s11172-010-0129-9

Cited by 5 publications

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“…A striking example of preferred exopolyhedral ligand orientation comes from comparison of the structures of metallacarboranes with pyrrolyl and boratabenzene as exopolyhedral ligands. In [3-(C4H4N)-closo-3,1,2-CoC2B9H11], Figure 7a, the orientation of the pyrrolyl ring is such that the N heteroatom lies above the C1−C2 connectivity of the carborane ligand [32], whilst in [3-(C5H5BMe)closo-3,1,2-RhC2B9H11], Figure 7b, the boratabenzene ligand is oriented such that its B heteroatom is positioned trans to C1−C2 [33]. Given that Zeff N > Zeff C > Zeff B, in the pyrrolyl ligand the N atom will contribute least to the π-FMOs and have the smallest STE, whilst in the boratabenzene ligand the B atom will contribute most to the π-FMOs and have the greatest STE.…”

Section: Elo Of η-Bound Ligandsmentioning

confidence: 99%

What Can We Learn from the Crystal Structures of Metallacarboranes?

Welch

2017

Crystals

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The determination of the molecular structures of metallacarboranes by X-ray diffraction remains critical to the development of the field, in some cases being the only viable way in which the overall architecture and the isomeric form of the molecule can be established. In such studies one problem frequently met is how to distinguish correctly {BH} and {CH} vertices, and this review begins by describing two relatively new methods, the Vertex-Centroid Distance (VCD) and Boron-Hydrogen Distance (BHD) methods, that have been developed to overcome the problem. Once the cage C atoms are located correctly, the resulting metallacarborane structure can frequently be analysed on the basis that cage B has a greater Structural Trans Effect (STE) than does cage C. In the absence of significant competing effects this gives rise to unequal M-L distances for a homogeneous ligand set and to a preferred Exopolyhedral Ligand Orientation (ELO) for a heterogeneous ligand set. ELO considerations can be used, amongst other things, to rank order the STEs of ligands and to identify suspect (in terms of cage C atom positions) metallacarborane structures.

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Section: Elo Of η-Bound Ligandsmentioning

confidence: 99%