Synthesis and characterisation of pseudocloso iridium and ruthenium diphenyl carbaboranes. Molecular structures of 1,2-Ph₂-3-(η-C₆H₆)-3,1,2-pseudocloso-RuC₂B₉H₉and 1,2-Ph₂-3-(cym)-3,1,2-pseudocloso-RuC₂B₉H₉(cym =p-cymene) and individual gauge for localised orbitals calculations on carbametallaboranes

On the Aqueous Solution Behavior of C-Substituted 3,1,2-Ruthenadicarbadodecaboranes

“…, to avoid base-promoted cleavage of the methoxy ester. The weighted average (see definition in Appendix B) of the 11 B NMR signals of 7 is +3.5 ppm, which is in accordance to previously reported values for pseudocloso-ruthenacarborane structures [16,22] that are formally derived from a closo structure via breaking of the C cluster -C cluster bond. In comparison, the weighted average of the 11 B signals for 2, 3, and 4 is −13.6, −12.8, and −11.7 ppm, respectively, which indicates closo structures.…”

“…For example, the Ru-B(6) distance in 7 is 2.979(2) Å, which is 0.5 Å shorter than in the corresponding undistorted closo-[3-(η 6 -p-cymene)-3,1,2-RuC 2 B 9 H 11 ] (8) ( Table 1) [9], and the B(6)-B(10) and the C(1)-B(4) bonds are 1.885(2) Å (vs. 1.759(1) Å in 8) and 1.636(2) Å (vs. 1.718(1) Å in 8), respectively. The B(4)-B(5) bond is, however, 0.04 Å longer in the pseudocloso structure 7, compared to the closo one (8), in contrast to what was observed by Welch for diphenyl-substituted pseudocloso-[3-(η 6 -arene)-1,2-Ph 2 -3,1,2-RuC 2 B 9 H 9 ] complexes, with respect to the corresponding closo-1,2-Ph 2 -C 2 B 10 H 10 [22]. [9], supporting the use of ruthenacarboranes as stable organometallic scaffolds for applications in medicine.…”

“…X-ray diffraction analysis of single crystals of 4 and 7 confirmed the closo and pseudocloso structures ( Figure 3), with C(1)• • • C(2) distances of 1.680(5) Å and 2.243(2) Å, respectively. It is not unexpected that complex 7 presents a pseudocloso structure, since closo-to-pseudocloso cluster deformation is a commonly encountered phenomenon in ruthenacarborane complexes, when carbon-bound substituents introduce additional electron density into the C cluster -C cluster bond, as in the case of phenyl substituents reported by Brain et al and Bould et al [16,22]. The structural distortions in 7 are generally in accordance with those reported by Welch and co-workers for pseudocloso-[3-(η 6 -arene)-1,2-Ph 2 -3,1,2-RuC 2 B 9 H 9 ] [22].…”

“…It is not unexpected that complex 7 presents a pseudocloso structure, since closo-to-pseudocloso cluster deformation is a commonly encountered phenomenon in ruthenacarborane complexes, when carbon-bound substituents introduce additional electron density into the C cluster -C cluster bond, as in the case of phenyl substituents reported by Brain et al and Bould et al [16,22]. The structural distortions in 7 are generally in accordance with those reported by Welch and co-workers for pseudocloso-[3-(η 6 -arene)-1,2-Ph 2 -3,1,2-RuC 2 B 9 H 9 ] [22]. For example, the Ru-B(6) distance in 7 is 2.979(2) Å, which is 0.5 Å shorter than in the corresponding undistorted closo-[3-(η 6 -p-cymene)-3,1,2-RuC 2 B 9 H 11 ] (8) ( Table 1) [9], and the B(6)-B(10) and the C(1)-B(4) bonds are 1.885(2) Å (vs. 1.759(1) Å in 8) and 1.636(2) Å (vs. 1.718(1) Å in 8), respectively.…”

Nature of weak inter- and intramolecular contacts in crystals 2. Character of electron delocalization and the nature of X—H...H—X (X = C, B) contacts in the crystal of 1-phenyl-o-carborane

“…Probably, a similar effect is observed in compound 2 and governs an appreciable elongation of the C(1)-C(2) bond in, e.g., triazine substituted derivatives of o carboranes 24,25 and the formation of pseudo closo structures of some metalla carboranes. [26][27][28][29] The ellipticity (ε) values for the bonds in the polyhe dron vary over rather wide intervals, namely, 0.09-7.29 for the crystal and 0.06-5.35 for isolated molecule 1. A high ε value indicates a deviation of ρ(r) from cylindri cal symmetry, being typical of the bonds with a π compo nent or of the "banana" bonds as is the case of, e.g., cyclopropane.…”