Calcium-amidoborane-ammine complexes: thermal decomposition of model systems.
Calcium-amidoborane-ammine complexes: thermal decomposition of model systems.
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DOI：
10.1002/chem.201102029
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发表时间：
2012-02
期刊：
影响因子：
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通讯作者：
S. Harder;Jan Spielmann;Briac Tobey
中科院分区：
文献类型：
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作者：
S. Harder;Jan Spielmann;Briac Tobey
制备了钙-氨基硼烷-氨络合物Ca（NH（2）BH（3））（2）<$（NH（3））（2的烃溶性模型体系，并对其结构进行了表征。通过RNH（2）BH（3）反应得到以下配合物：（R = H、Me、iPr、DIPP; DIPP = 2，6-二异丙基苯基）与Ca（DIPP-nacnac）（NH（3））（2）（DIPP-nacnac = DIPP-NC（Me）CHC（Me）N-DIPP）：CA（DIPP-nacnac）（NH（2）BH（3））N（NH（3））（2），Ca（DIPP-nacnac）（NH（2）BH（3））NH（3））（3）、Ca（DIPP-nacnac）[NH（Me）BH（3）] NH（3））（2）、Ca（DIPP-nacnac）[NH（iPr）BH（3）] NH（3））（2）和Ca（DIPP-nacnac）[NH（DIPP）BH（3）] NH（3）。Ca（DIPP-nacnac）（NH（2）BH（3））·（NH（3）（3））的晶体结构显示NH（2）BH（3）（-）单元完全嵌入BH····HN相互作用网络中（范围：1.97（4）-2.39（4）Å），主要存在于NH（3）配体和BH（3）基团之间。此外，NH（3）配体与配体中心碳原子之间存在N-H-N-N-C相互作用.将这些钙-氨基硼烷-氨络合物在苯中的溶液逐步加热至60 °C并热分解。结果表明：1）NH（3）与DIPP-nacnac阴离子竞争质子化; 2）NH（3）配体与Ca（2+）的结合较松散，加热后部分被消除。获得了[Ca（DIPP-nacnac）（NH（2）BH（3））<$（NH（3））]（∞）、Ca（DIPP-nacnac）（NH（2）BH（3））<$（NH（3））<$（THF）和[Ca（DIPP-nacnac）{NH（iPr）BH（3）}]（2）的晶体结构。3)与NH（R）BH（3）中取代基R的性质无关，在约50 °C下观察到H（2）的形成。4)在所有情况下，形成的配合物[Ca（DIPP-nacnac）（NH（2））]（2）作为热分解的主要产物，其二聚体的性质通过单晶分析证实。我们提出钙-氨基硼烷-氨络合物的热分解经过一个中间体钙-氢化物-氨络合物，它消除氢和[Ca（DIPP-nacnac）（NH（2））]（2）。这是可能的，金属氨基化合物的形成也是一个重要的反应途径的金属-氨基硼烷-氨络合物在固态下的分解。
Hydrocarbon-soluble model systems for the calcium-amidoborane-ammine complex Ca(NH(2)BH(3))(2)⋅(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))⋅(NH(3))(2) (DIPP-nacnac = DIPP-NC(Me)CHC(Me)N-DIPP): Ca(DIPP-nacnac)(NH(2)BH(3))⋅(NH(3))(2), Ca(DIPP-nacnac)(NH(2)BH(3))⋅(NH(3))(3), Ca(DIPP-nacnac)[NH(Me)BH(3)]⋅(NH(3))(2), Ca(DIPP-nacnac)[NH(iPr)BH(3)]⋅(NH(3))(2), and Ca(DIPP-nacnac)[NH(DIPP)BH(3)]⋅NH(3). The crystal structure of Ca(DIPP-nacnac)(NH(2)BH(3))⋅(NH(3)(3) showed a NH(2)BH(3)(-) unit that was fully embedded in a network of BH⋅⋅⋅HN interactions (range: 1.97(4)-2.39(4) Å) that were mainly found between NH(3) ligands and BH(3) groups. In addition, there were N-H⋅⋅⋅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) Competing protonation of the DIPP-nacnac anion by NH(3) was observed; 2) 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))⋅(NH(3))](∞), Ca(DIPP-nacnac)(NH(2)BH(3))⋅(NH(3))⋅(THF), and [Ca(DIPP-nacnac){NH(iPr)BH(3)}](2) were obtained. 3) 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) 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.