How to Make 8,1,2-closo-MC2B9 Metallacarboranes

Three examples of the rare 8,1,2-closo-MC2B9 isomeric form of an icosahedral metallacarborane have been isolated as unexpected trace products in reactions. Seeking to understand how these were formed we considered both the nature of the reactions that were being undertaken and the nature of the coproducts. This led us to propose a mechanism for the formation of the 8,1,2-closo-MC2B9 species. The mechanism was then tested, leading to the first deliberate synthesis of an example of this isomer. Thus, deboronation of 4-(η-C5H5)-4,1,8-closo-CoC2B10H12 selectively removes the B5 vertex to yield the dianion [nido-(η-C5H5)CoC2B9H11]2−, oxidative closure of which affords 8-(η-C5H5)-8,1,2-closo-CoC2B9H11 in moderate yield

Activation of carbon dioxide and carbon disulfide by a scandium N-heterocyclic carbene complex

A Sc NHC complex readily activates three equivalents of CO2 showing ‘Frustrated Lewis Pair’ type reactivity with each metal–carbene bond, but whilst CS2 is also activated by the labile carbenes, no metal involvement is observed. Graphical abstract: Activation of carbon dioxide and carbon disulfide by a scandium N-heterocyclic carbene comple

Synthesis and solvent dependent reactivity of chelating bis-N-heterocyclic carbene complexes of Fe(II) hydrides

The synthesis and isolation of low coordinate methylenebis-(N-DIPP-imidazole-2-ylidene)iron(II)hydrides, ((DIPPC)2CH2)FeH2-yIy ((DIPP = 2,6-di-isopropylphenyl, y = 1 or 0), was complicated by competitive reactions with solvent, rapid reductive elimination of H2 and/or dissociation of the bis-N-heterocyclic carbene ligand. Addition of KH to ((DIPPC)2CH2)FeI2 in THF/haloalkane mixtures enabled a short lived mono-hydride to be trapped by reaction with CH2Cl2 or cyclo-heptylbromide to form ((DIPPC)2CH2)FeI(X) (X = Cl or Br, respectively). Toluene coordination stabilises iron-mono hydride complexes as ((DIPPC)2CH2)FeIIH{η6-(toluene)} species, which can be isolated in low yield from combination of borohydride salts and ((DIPPC)2CH2)FeI2 in toluene, including an imidazole C4 deprotonated carbene-borane, methylene(N-DIPP-imidazole-2-ylidene)(N-DIPP-4-triethyl-borane-imidazole-2-ylidene)](hydrido)(η6-toluene)iron. In the absence of toluene, or at short reaction times compounds with empirical formula ((DIPPC)2CH2)Fe(H)(HB(R)3)·LiI (R = Et or sec-Bu) that function as a masked Fe(II)-dihydride are isolated. Whilst ((DIPPC)2CH2)Fe(H)(HB(R)3)·LiI was stable for days in Et2O, more polar solvents (MeCN, THF) led to formation of the carbene borane adducts ((DIPPC)2CH2)(BR3)2. The addition of CO or cyclo-heptylbromide to ((DIPPC)2CH2)Fe(H)(HB(R)3)·LiI formed ((DIPPC)2CH2)Fe(CO)3 and ((DIPPC)2CH2)FeBr2, respectively with BR3 evolved from both reactions as a by-product

CCDC 851126: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

CCDC 851122: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

CCDC 851127: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures

CCDC 851125: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures