ABSTRACT
Spontaneous ion separation of the scorpionate beryllium complex, TpBeI 1 (Tp = 1-trispyrazolylborate), occurs upon treatment with THF, yielding [TpBe(thf)]I 2, which was characterized by heteronuclear NMR spectroscopy (1H, 9Be, 13C) and structurally characterized by single crystal X-ray diffraction. 2 represents a rare example of a structurally characterized monocationic beryllium complex, and to the best of our knowledge, the synthesis of 2 by a solvent-induced ion separation has previously only been observed in the reactions of beryllium dihalides with strong Lewis bases.
ABSTRACT
[Ph4 P]2 [Be(N3 )4 ] (1) and [PNP]2 [Be(N3 )4 ] (2; PNP=Ph3 PNPPh3 ) were synthesized by reacting Be(N3 )2 with [Ph4 P]N3 and [PNP]N3 . Compound 1 represents the first structurally characterized homoleptic beryllium azide. The electronic structure and bonding situation in the tetraazidoberyllate dianion [Be(N3 )4 ]2- were investigated by quantum-chemical calculations (NPA, ELF, LOL).
ABSTRACT
Hydrocarbon-soluble model systems for the calcium-amidoborane-ammine complex Ca(NH(2)BH(3))(2)â (NH(3))(2) were prepared and structurally characterized. The following complexes were obtained by the reaction of RNH(2)BH(3) (R = H, Me, iPr, DIPP; DIPP = 2,6-diisopropylphenyl) with Ca(DIPP-nacnac)(NH(2))â (NH(3))(2) (DIPP-nacnac = DIPP-NC(Me)CHC(Me)N-DIPP): Ca(DIPP-nacnac)(NH(2)BH(3))â (NH(3))(2), Ca(DIPP-nacnac)(NH(2)BH(3))â (NH(3))(3), Ca(DIPP-nacnac)[NH(Me)BH(3)]â (NH(3))(2), Ca(DIPP-nacnac)[NH(iPr)BH(3)]â (NH(3))(2), and Ca(DIPP-nacnac)[NH(DIPP)BH(3)]â NH(3). The crystal structure of Ca(DIPP-nacnac)(NH(2)BH(3))â (NH(3)(3) showed a NH(2)BH(3)(-) unit that was fully embedded in a network of BHâ â â HN interactions (range: 1.97(4)-2.39(4)â Å) that were mainly found between NH(3) ligands and BH(3) groups. In addition, there were N-Hâ â â C interactions between NH(3) ligands and the central carbon atom in the ligand. Solutions of these calcium-amidoborane-ammine complexes in benzene were heated stepwise to 60 °C and thermally decomposed. The following main conclusions can be drawn: 1)â Competing protonation of the DIPP-nacnac anion by NH(3) was observed; 2)â The NH(3) ligands were bound loosely to the Ca(2+) ions and were partially eliminated upon heating. Crystal structures of [Ca(DIPP-nacnac)(NH(2)BH(3))â (NH(3))](∞), Ca(DIPP-nacnac)(NH(2)BH(3))â (NH(3))â (THF), and [Ca(DIPP-nacnac){NH(iPr)BH(3)}](2) were obtained. 3)â Independent of the nature of the substituent R in NH(R)BH(3), the formation of H(2) was observed at around 50 °C. 4)â In all cases, the complex [Ca(DIPP-nacnac)(NH(2))](2) was formed as a major product of thermal decomposition, and its dimeric nature was confirmed by single-crystal analysis. We proposed that thermal decomposition of calcium-amidoborane-ammine complexes goes through an intermediate calcium-hydride-ammine complex which eliminates hydrogen and [Ca(DIPP-nacnac)(NH(2))](2). It is likely that the formation of metal amides is also an important reaction pathway for the decomposition of metal-amidoborane-ammine complexes in the solid state.