Synthetic and structural studies on C-ethynyl- and C-bromo-carboranes

Synthesis of Iminoboryl o-Carboranes by Lewis Base Promoted Aminoborirane-to-Iminoborane Isomerization

The iminoboryl o-carboranes (Me₃Si)-Cb-B≡N-R (Cb = B₁₀C₂H₁₀, 3a, R = SiMe₃; 3b, R = ^tBu) have been successfully synthesized by tetrahydrofuran (THF)-promoted isomerization from the corresponding o-carborane-fused aminoboriranes Cb{BN(SiMe₃)R} (2). The synthetic protocol of the previously reported borirane 2a was optimized. The borirane Cb{BN(SiMe₃)^tBu} (2b) and the iminoboranes 3a and 3b were fully characterized by NMR, IR, and single-crystal X-ray diffraction analyses. The borirane 2a isomerizes more readily than 2b. The kinetics study revealed a bimolecular mechanism between borirane and THF, which is in good agreement with the computationally proposed reaction pathway. The title compounds are thermally robust, but compound 3a dimerized in the presence of a catalytic amount of ^tBuNC to give the cyclodimer 4. Quick equilibrium between 4 and the isonitrile adduct 4·^tBuNC was observed in solution.

1,12-Diiodo-Ortho-Carborane: A Classic Textbook Example of the Dihalogen Bond

The crystal structure of 1,12-diiodo-ortho-carborane 1,12-I2-1,2-C2B10H10 was determined by single crystal X-ray diffraction. In contrary to earlier studied 1,12-dibromo analogue 1,12-Br2-1,2- C2B10H10, its crystal packing is governed by the presence of the intermolecular I⋯I dihalogen bonds between the iodine atom attached to the carbon atom (acceptor) and the iodine atom attached to the antipodal boron atom (donor) of the carborane cage. The observed dihalogen bonds belong to the II type and are characterized by classical parameters: shortened I⋯I distance of 3.5687(9) Å, C–I⋯I angle of 172.61(11)° and B–I⋯I angle of 92.98(12)°.

Efficient labeling of organic molecules using 13C elemental carbon: universal access to 13C2-labeled synthetic building blocks, polymers and pharmaceuticals

Synthetic methodology enabled by ¹³C-elemental carbon is reported. Calcium carbide Ca¹³C₂ was applied to introduce a universal ¹³C₂ unit in the synthesis of labeled alkynes, O,S,N-vinyl derivatives, labeled polymers and ¹³C₂-pyridazine drug core.

Synthesis and characterization of binuclear half-sandwich metal (Co, Ir and Ru) complexes containing ancillary ortho-carborane-1,2-dithiolato ligands

The assembly of soluble, air-stable, binuclear structures, namely {(p-cymene)Ru[S(2)C(2)(B(10)H(10))]}(2)(micro-pyz), {Cp*Co[S(2)C(2)(B(10)H(10))]}(2)(micro-pyz), {Cp*Co[S(2)C(2)(B(10)H(10))]}(2)(micro-bpy), {Cp*Co[S(2)C(2)(B(10)H(10))]}(2)(micro-bpe) and {Cp*Ir[E(2)C(2)(B(10)H(10))]}(2)(micro-bpo) (E = S (), Se), in which organometallic units are bridged by pyridyl-based organic linkers, are synthesized. The complexes have been fully characterized by IR and NMR spectroscopy, as well as elemental analysis. The molecular structures are established through X-ray crystallography.