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Penta-iodination of the B2–6 positions of the {CB11} monocarborane cluster is reported. Products of the structure [2,3,4,5,6-I5-CB11H6-12-X]− (X = H, Me, Et, Ph, Br, I) were obtained and fully characterized. X-ray crystal structures of three new compounds confirm this particular substitution pattern. The synthetic method relies on palladium catalysis/B–H activation, assisted by the C1-COOH directing group. The one-pot procedure enables penta-iodination and subsequent decarboxylation under convenient conditions. The B2–6 regioselectivity is complementary to the commonly observed reactivity of {CB11} clusters, which follows the trend B12 > B7–11 > B2–6 for electrophilic substitution. Thus, for the first time upper-belt halogenation is achieved without prior modification of the lower-belt positions. [ABSTRACT FROM AUTHOR]

The Sonogashira cross coupling between the monocarborane cluster 12-ethynylmonocarba-closo-dodecaborate [CB11H11-12-C≡CH]− and bromoarenes under Pd catalysis has been developed, providing access to aryl carboranyl alkynes in yields of 42–95%. The transformations proceed under mild conditions and with high functional group tolerance using commercially available coupling partners. X-ray structural analyses and the identification of an unusual phosphonium zwitterion byproduct are reported as well. [ABSTRACT FROM AUTHOR]

The anionic monocarborane alkyne [12-(HC≡C)-CB11H11]− was employed as a ligand towards Cu(I) to form terminal alkyne complexes. Spectroscopic methods and X-ray crystallography allowed for a detailed structural analysis of complexes with nitrogen ligands, which are the first examples featuring carborane-C≡CH → metal π coordination. Addition of phosphines to compound 2 afforded homoleptic Cu(I) complexes [Cu(PR3)n]+ (4), in which case the carborane becomes a non-coordinating anion. Polymeric acetylide 5 was obtained in almost quantitative yield from 2 and proved to be a suitable precursor to heterobimetallic Cu(I)/M(II) (M = Pd, Pt) alkynide complexes with side-on and end-on coordination to the metal centers. [ABSTRACT FROM AUTHOR]

The regioselective derivatization of the monocarba-closo-dodecaborate anion via catalytic B–H bond activation is reported. Amide directing groups in combination with rhodium and iridium catalysts allowed for the direct functionalization of cage boron vertices. Products comprising B–C, B–N and B–Cl bonds were synthesized. As a key intermediate of the B–H activation step, an iridium complex with a direct B–Ir interaction was isolated and fully characterized by spectroscopic methods as well as X-ray crystallography. [ABSTRACT FROM AUTHOR]

Reactions of 7,10-disubstituted diazafluoranthene derivatives with three different silver(I) salts AgX (X = [PF6]-, [SbF6]-, [CB11HCl11]-) and [Cu(CH3CN)4]PF6 afforded complexes exhibiting five different motifs. The crystal structures of the free ligands and nine new complexes from this series of reactions are reported. The use of 2,5-di-tert-butyl-7,10-di(pyridin-2-yl)-8,9-diazafluoranthene as a ligand leads to the formation of the tetranuclear compounds [Ag4(C32H30N4)4][PF6]4·3C6H6·4MeCN, [Ag4(C32H30N4)4]-[SbF6]4·4C5H12 and [Cu4(C32H30N4)4][PF6]4·8C3H6O, which exhibit "propeller" and saddle-type geometry, respectively, as well as a dinuclear complex [Ag2(C32H30N4)2][CHB11Cl11]2·4C6H4Cl2·CH2Cl2. The reactions involving the less sterically hindered 2,5-di-tert-butyl-7,10-di-(pyrimidin-2-yl)-8,9-diazafluoranthene and 2,5-di-tert-butyl-7,10-di(thiazol-2-yl)-8,9-diazafluoranthene afforded crystals of the dinuclear complexes [Ag2(C30H28N6)2][PF6]2·0.5CH2Cl2·0.5C6H5Cl·0.5C6H12, [Ag2(C30H28N6)2][SbF6]2·C3H6O·0.5C6H14·0.5C6H6, the polymeric species [Ag2(C28H26N4S2)2]n·2n[PF6]n·nC3H6O and the tetranuclear compounds [Cu4(C26H25N4S2)4][PF6]4·2CHCl3·2C3H6O and [Cu4(C30H28N6)4][PF6]4·2.17H2O, which possess saddle and grid-like architectures, respectively. Conformational analysis of the free ligands showed that they exhibit N-C-C-N torsion angles ranging from syn clinal (58°) to fully anti-periplanar conformations; the syn clinal conformation dominates in the complexes. The relative energies of the possible structural conformations of the synthesized ligands, as well as of oxazole disubstituted diazafluoranthenes, were calculated using density functional theory at the B97D/Def2-TZVPP level of theory. [ABSTRACT FROM AUTHOR]

The Sonogashira cross coupling between the monocarborane cluster 12-ethynylmonocarba-closo-dodecaborate [CB11H11-12-C≡CH]− and bromoarenes under Pd catalysis has been developed, providing access to aryl carboranyl alkynes in yields of 42–95%. The transformations proceed under mild conditions and with high functional group tolerance using commercially available coupling partners. X-ray structural analyses and the identification of an unusual phosphonium zwitterion byproduct are reported as well. [ABSTRACT FROM AUTHOR]