1,1′-Bis( ortho -carborane) as a κ 2 co-ligand

Synthesis and cluster structure distortions of biscarborane dithiol, thioether, and disulfide

The synthesis and structural characterization of the first sulfur-containing derivatives of the C,C-biscarborane {ortho-C2B10}2 cluster - thiol, thioether, and disulfide - are reported. The biscarboranyl dithiol (1-HS-C2B10H10)2 exhibits an exceedingly long intracluster carbon-carbon bond length of 1.858(3) Å, which is attributed to the extensive interaction between the lone pairs of the thiol groups and the unoccupied molecular orbital of the carborane cluster. The structures of the doubly deprotonated biscarboranyl dithiolate anion (1-S-C2B10H10)22- with various counter cations feature an even longer carbon-carbon bond length of 2.062(10) Å within the cluster along with a short carbon-sulfur bond of 1.660(7) Å, both indicative of significant delocalization of electron density from the sulfur atoms into the cluster.

Synthesis, Structure, and Spectroscopy of the Biscarboranyl Stannylenes ()Sn·THF and K2[()Sn]2 ( = 1,1'(ortho-Biscarborane)) and Dibiscarboranyl Ethene ()CH=CH()

Two compounds containing a Sn(II) atom supported by a bidentate biscarborane ligand have been synthesized via salt metathesis. The synthetic procedures for (bc)Sn·THF (bc = 1,1' (ortho-carborane) (1) and K2[(bc)Sn]2 (2) involved the reaction of K2[bc] with SnCl2 in either a THF solution (1) or in a benzene/dichloromethane solvent mixture (2). Using the same solvent conditions as those used for 2 but using a shorter reaction time gave a dibiscarboranyl ethene (3). The products were characterized by 1H, 13C, 11B, 119Sn NMR, UV-vis, and IR spectroscopy, and by X-ray crystallography. The diffraction data for 1 and 2 show that the Sn atom has a trigonal pyramid environment and is constrained by the bc ligand in a planar five-membered C4Sn heterocycle. The 119Sn NMR spectrum of 1 displays a triplet of triplets pattern signal, which is unexpected given the absence of a Sn-H signal in the 1H NMR, IR spectrum, and X-ray crystallographic data. However, a comparison with other organotin compounds featuring a Sn atom bonded to carboranes reveal similar multiplets in their 119Sn NMR spectra, likely arising from long-range nuclear spin-spin coupling between the carboranyl 11B and 119Sn nuclei. Compound 3 displays structural and spectroscopic characteristics typical of conjugated alkenes.

C,C'-Ru to C,B'-Ru isomerisation in bis(phosphine)Ru complexes of [1,1'-bis(ortho-carborane)]

We report herein the first example of the controlled isomerisation of a C,C'-bound (to metal) bis(ortho-carborane) ligand to C,B'-bound with no other change in the molecule. Since the C and B vertices of carboranes have different electron-donating properties this transformation allows the reactivity of the metal centre to be fine-tuned.

Synthesis of 9-borafluorene analogues featuring a three-dimensional 1,1'-bis(o-carborane) backbone

The synthesis of [1,1'-bis(o-carboranyl)]boranes was achieved through the deprotonation of 1,1'-bis(o-carborane) reagents followed by salt metathesis with (iPr)2NBCl2. X-ray crystallography confirms planar central BC4 rings and Gutmann-Beckett studies reveal an increase in Lewis acidity at the boron center in comparison to their biphenyl congener, 9-borafluorene.

Double deboronation and homometalation of 1,1′-bis(ortho-carborane)

Diastereomeric diruthenium and dicobalt species derived from double deboronation and metalation of 1,1′-bis(ortho-carborane) have been prepared and characterised.

Large, weakly basic bis(carboranyl)phosphines: an experimental and computational study

Bis(carboranyl)phosphines and their {AuCl} and {Se} derivatives have been the subject of experimental and computational studies.

Luminescent Metal Complexes Featuring Photophysically Innocent Boron Cluster Ligands

We report the synthesis and characterization of a series of d8 metal complexes featuring robust and photophysically innocent strong-field chelating 1,1'-bis(o-carborane) (bc) ligand frameworks. A combination of UV-Vis spectroscopy, single crystal X-ray structural analysis, and DFT calculations of these species suggest that the dianionic bc ligand does not contribute to any visible metal-to-ligand charge transfer (MLCT) transitions, yet it provides a strong ligand field in these complexes. Furthermore, a bc-based Pt(II) complex containing a 4,4'-di-tert-butyl-2,2'-bipyridine ligand (dtb-bpy) has been prepared and was found to display blue phosphorescent emission dominated by MLCT from the Pt(II) center to the dtb-bpy ligand. Importantly, the bulky three-dimensional nature of the bc ligand precludes intermolecular Pt(II)⋯Pt(II) interactions in the solid state where the resulting compounds retain their emission properties. This study opens a potentially new avenue for designing organic light-emitting diode (OLED) materials with tunable properties featuring photophysically innocent boron-rich cluster ligands.

Unprecedented flexibility of the 1,1′-bis(o-carborane) ligand: catalytically-active species stabilised by B-agostic B–H⇀Ru interactions

The compound (p-cymene)Ru[(C₂B₁₀H₁₀)₂], an effective Lewis acid catalyst, is the precursor to a number of products in which the 1,1′-bis(o-carborane) unit displays an unprecedented range of ligating modes.

Unique properties of C,C′-linked nido-biscarborane tetraanions. Synthesis, structure and bonding of ruthenium monocarbollide via unprecedented cage carbon extrusion

An unprecedented bisruthenacarborane (RuCB₁₀) bearing a novel 6π-electron carboranyl ligand [C₂B₁₀]²⁻has been isolated and structurally characterized from the reaction of a C,C′-linkednido-biscarborane tetraanion with {Ru(p-cymene)}²⁺.

Developing nitrosocarborane chemistry

New nitrosocarboranes or their hydroxylamine or Diels–Alder cycloadducts have been prepared and fully characterised.