Synthesis and Characterization of Primary Aluminum Parent Amides and Phosphides

The synthesis and characterization of the sterically crowded primary alanes (AriPr4AlH2)2 (AriPr4 = C6H3-2,6­(C6H3-2,6-iPr2)2) and (AriPr8AlH2)2 (AriPr8 = C6H-2,6­(C6H2-2,4,6-iPr6)2-3,5-iPr2) are described. They, along with their previously reported less-hindered analogue (ArMe6AlH2)2 (ArMe6 = C6H3-2,6­(C6H2-2,4,6-Me3)2), were reacted with ammonia to give the parent amido alanes {ArxAl­(H)­NH2}2 (Arx = ArMe6, 1; AriPr4, 2; AriPr8, 3), which are the first well-characterized hydride amido derivatives of aluminum and are relatively rare examples of parent aluminum amides. In contrast, the reaction of (ArMe6AlH2)2 with phosphine yielded the structurally unique Al/P cage species {(ArMe6Al)3(μ-PH2)3(μ-PH)­PH2} (4) as the major product and a smaller amount of {(ArMe6Al)4(μ-PH2)4(μ-PH)} (5) as a minor product. All compounds were characterized by NMR and IR spectroscopy, while compounds 2–5 were also characterized by X-ray crystallography.本研究报道了空间位阻受阻的伯铝烷(AriPr4AlH2)2（AriPr4 = C6H3-2,6­(C6H3-2,6-二异丙基)2）与(AriPr8AlH2)2（AriPr8 = C6H-2,6­(C6H2-2,4,6-六异丙基)2-3,5-二异丙基）的合成与表征。将上述两种伯铝烷与此前已报道的位阻更小的类似物(ArMe6AlH2)2（ArMe6 = C6H3-2,6­(C6H2-2,4,6-三甲基)2）一同与氨气反应，得到了母体酰胺铝烷{ArxAl(H)NH2}2（Arx = ArMe6，产物1；AriPr4，产物2；AriPr8，产物3）。该类化合物是首例经充分表征的铝基氢化物酰胺衍生物，同时亦是较为罕见的母体铝酰胺类化合物。与之相反，(ArMe6AlH2)2与膦的反应主要生成结构独特的铝/磷笼状物种{(ArMe6Al)3(μ-PH2)3(μ-PH)PH2}（产物4），同时伴随少量次要产物{(ArMe6Al)4(μ-PH2)4(μ-PH)}（产物5）。所有产物均通过核磁共振波谱（Nuclear Magnetic Resonance, NMR）与红外光谱（Infrared Spectroscopy, IR）进行表征，其中产物2至5还通过X射线晶体衍射完成了结构鉴定。