Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States.
Inorg Chem. 2012 Jan 16;51(2):1127-41. doi: 10.1021/ic202307a. Epub 2011 Dec 23.
The binary group 15 polyazides As(N(3))(3), Sb(N(3))(3), and Bi(N(3))(3) were stabilized by either anion or donor-acceptor adduct formation. Crystal structures are reported for Bi(N(3))(4), Bi(N(3))(5), bipy·Bi(N(3))(5), Bi(N(3))(6), bipy·As(N(3))(3), bipy·Sb(N(3))(3), and (bipy)(2)·Bi(N(3))(3). The lone valence electron pair on the central atom of these pnictogen(+III) compounds can be either sterically active or inactive. The Bi(N(3))(5) anion possesses a sterically active lone pair and a monomeric pseudo-octahedral structure with a coordination number of 6, whereas its 2,2'-bipyridine adduct exhibits a pseudo-monocapped trigonal prismatic structure with CN 7 and a sterically inactive lone pair. Because of the high oxidizing power of Bi(+V), reactions aimed at Bi(N(3))(5) and Bi(N(3))(6) resulted in the reduction to bismuth(+III) compounds by N(3). The powder X-ray diffraction pattern of Bi(N(3))(3) was recorded at 298 K and is distinct from that calculated for Sb(N(3))(3) from its single-crystal data at 223 K. The (bipy)(2)·Bi(N(3))(3) adduct is dimeric and derived from two BiN(8) square antiprisms sharing an edge consisting of two μ(1,1)-bridging N(3) ligands and with bismuth having CN 8 and a sterically inactive lone pair. The novel bipy·As(N(3))(3) and bipy·Sb(N(3))(3) adducts are monomeric and isostructural and contain a sterically active lone pair on their central atom and a CN of 6. A systematic quantum chemical analysis of the structures of these polyazides suggests that the M06-2X density functional is well suited for the prediction of the steric activity of lone pairs in main-group chemistry. Furthermore, it was found that the solid-state structures can strongly differ from those of the free gas-phase species or those in solutions and that lone pairs that are sterically inactive in a chemical surrounding can become activated in the free isolated species.
二元 15 叠氮化物 As(N(3))(3)、Sb(N(3))(3) 和 Bi(N(3))(3) 通过阴离子或给体-受体加合物形成得到稳定。报道了 Bi(N(3))(4)、Bi(N(3))(5)、bipy·Bi(N(3))(5)、Bi(N(3))(6)、bipy·As(N(3))(3)、bipy·Sb(N(3))(3) 和 (bipy)(2)·Bi(N(3))(3) 的晶体结构。这些 p 区元素(+III)化合物中心原子上的孤对电子对可以是空间活跃的，也可以是空间不活跃的。Bi(N(3))(5)阴离子具有空间活跃的孤对电子对和单体拟八面体结构，配位数为 6，而其 2,2'-联吡啶加合物则具有拟单核帽三角棱柱结构，配位数为 7，孤对电子对空间不活跃。由于 Bi(+V) 的高氧化能力，针对 Bi(N(3))(5)和Bi(N(3))(6)的反应导致通过N(3)还原为 Bi(+III)化合物。在 298 K 下记录了 Bi(N(3))(3)的粉末 X 射线衍射图，与从其单晶数据在 223 K 下计算的 Sb(N(3))(3)的粉末 X 射线衍射图明显不同。(bipy)(2)·Bi(N(3))(3)加合物是二聚体，由两个 BiN(8) 正方形反棱柱共享由两个 μ(1,1)-桥接 N(3)配体组成的边缘组成，其中铋具有 CN 8 和空间不活跃的孤对电子对。新型 bipy·As(N(3))(3)和 bipy·Sb(N(3))(3)加合物是单体的，结构相同，它们的中心原子上有一个空间活跃的孤对电子对，配位数为 6。对这些多叠氮化物结构的系统量子化学分析表明，M06-2X 密度泛函非常适合于预测主族化学中孤对电子对的空间活性。此外，发现固态结构可以与气相自由物种或溶液中的结构强烈不同，并且在化学环境中空间不活跃的孤对电子对在自由孤立物种中可以变得活跃。
