41655-52-1Relevant articles and documents
Syntheses and reductions of C-dimesitylboryl-1,2-dicarba-closo-dodecaboranes
Kahlert, Jan,B?hling, Lena,Brockhinke, Andreas,Stammler, Hans-Georg,Neumann, Beate,Rendina, Louis M.,Low, Paul J.,Weber, Lothar,Fox, Mark A.
, p. 9766 - 9781 (2015/06/08)
Two C-dimesitylboryl-1,2-dicarba-closo-dodecaboranes, 1-(BMes2)-2-R-1,2-C2B10H10 (1, R = H, 2, R = Ph), were synthesised by lithiation of 1,2-dicarba-closo-dodecaborane and 1-phenyl-1,2-dicarba-closo-dodecaborane, respectively, with n-butyllithium and subsequent reaction with fluorodimesitylborane. These novel compounds were structurally characterised by X-ray crystallography. Compounds 1 and 2 are hydrolysed on prolonged exposure to air to give mesitylene and boronic acids 1-(B(OH)2)-2-R-1,2-C2B10H10 (3, R = H, 4, R = Ph respectively). Addition of fluoride anions to 1 and 2 resulted in boryl-carborane bond cleavage to give dimesitylborinic acid HOBMes2. UV absorption bands at 318-333 nm were observed for 1 and 2 corresponding to local π-π-transitions within the dimesitylboryl groups while visible emissions at 541-664 nm with Stokes shifts of 11 920-16 170 cm-1 were attributed to intramolecular charge transfer transitions between the mesityl and cluster groups. Compound 2 was shown by cyclic voltammetry to form a stable dianion on reduction. NMR spectra for the dianion [2]2- were recorded from solutions generated by reductions of 2 with alkali metals and compared with NMR spectra from reductions of 1,2-diphenyl-ortho-carborane 5. On the basis of observed and computed 11B NMR shifts, these nido-dianions contain bowl-shaped cluster geometries. The carborane is viewed as the electron-acceptor and the mesityl group is the electron-donor in C-dimesitylboryl-1,2-dicarba-closo-dodecaboranes.
Group 4 metallacarboranes of constrained geometries derived from B(cage)- and cage)-silylamido-substituted carborane ligands: A synthetic and structural investigation
Wang, Jianhui,Zhu, Yinghuai,Li, Shoujian,Zheng, Chong,Maguire, John A.,Hosmane, Narayan S.
, p. 173 - 181 (2007/10/03)
The reactions of RNHSi(Me)2Cl (1, R= t -Bu; 2, R=2,6-(Me2CH)2C6H3) with the carborane ligands, nido-1-Na(C4H8O)-2, 3-(SiMe3)2-2,3-C2B4 H5 (3) and Li[ closo-1-R′-1,2-C2 B10H10] (4), produced two kinds of neutral ligand precursors, nido-5-[Si(Me)2N(H)R]-2, 3-(SiMe3)2-2,3-C2B4 H5, (5, R = t- Bu) and closo-1-R′-2-[Si(Me)2 N(H)R]-1,2-C2B10H10 (6, R= t -Bu, R′=Ph; 7, R=2,6-(Me2CH)2C6 H3, R′=H), in 85, 92, and 95% yields, respectively. Treatment of closo-2-[Si(Me)2NH(2,6-(Me2CH) 2C6H3)]-1,2-C2B 10H11 (7) with three equivalents of freshly cut sodium metal in the presence of naphthalene produced the corresponding cage-opened sodium salt of the carbons apart carborane trianion, [ nido -3-{Si(Me)2N(2,6-(Me2CH) 2C6H3)}-1,3-C2B10 H11]3- (8) in almost quantitative yield. The reaction of the trianion, 8, with anhydrous MCl4 (M=Ti and Zr) in 1:1 molar ratio in dry tetrahydrofuran (THF) at -78 °C, resulted in the formation of the corresponding half-sandwich neutral d0-metallacarborane, closo-1-M[(Cl)(THF)n]-2- [1′-η1σ-N(2,6-(Me2CH)2 C6H3)(Me)2Si]-2,4-η6 -C2B10H11 (M=Ti (9), n = 0; M=Zr (10), n = 1) in 47 and 36% yields, respectively. All compounds were characterized by elemental analysis, 1H-, 11B-, and 13C-NMR spectra and IR spectra. The carborane ligand, 7, was also characterized by single crystal X-ray diffraction. Compound 7 crystallizes in the monoclinic space group P 21/ c with a = 8.2357(19) A?, b = 28.686(7) A?, c = 9.921(2) A?; β= 93.482(4)°; V = 2339.5(9) A?3, and Z = 4. The final refinements of 7 converged at R = 0.0736; wR= 0.1494; GOF=1.372 for observed reflections.
Synthesis and Structure of Carborane-Substituted Cyclic and Polymeric Phosphazenes
Allcock, H. R.,Scopelianos, A. G.,O'Brien, J. P.,Bernheim, M. Y.
, p. 350 - 357 (2007/10/02)
The synthesis of the first carborane-substituted cyclophosphazenes together with the preparation, by two different approaches, of the first carborane-substituted phosphazene linear polymers is reported.The cyclic derivatives IV are both precursors and model compounds for the analogous polymeric derivatives VI.The crystal and molecular structure of IV (R = phenyl) has been investigated by single-crystal X-ray diffraction techniques.The molecule contains a planar phosphazene trimer ring bound directly to the phenyl carboranyl group through a P-C bond.The absence of steric and electronic influences by the phosphazene and carboranyl units on each other is discussed.The crystal of IV (R = phenyl) are monoclinic with the space group P21/n and with a = 9.476 (3) Angstroem, b = 12.984 (2) Angstroem, c = 18.726 (3) Angstroem and β = 100.11 (3) deg with V = 2268.2 (3) Angstroem3 and Z = 4.The P-N bond distances are all similar and average 1.574 Angstroem.The P-C bond length is 1.820 Angstroem, and the Cl-P-C angle was found to be 102.4 deg.The reaction between high molecular weight poly(dichlorophosphazene), (NPCl2)n, and methyl- or phenyl-1-lithio-o-carborane was also studied.Chlorine substitution is a slow process, and is accompanied by chain cleavage.The nucleophilic replacement of the halogen atoms yielded high polymers of structure IX that contain up to 15percent of the side groups as carboranyl units.The remaining chlorine atoms were replaced by treatment with sodium trifluoroethoxide.The properties and structure of the macromolecules are discussed.
