De Anangsha, Zhang Qian-Fan, Mondal Bijan, Cheung Ling Fung, Kar Sourav, Saha Koushik, Varghese Babu, Wang Lai-Sheng, Ghosh Sundargopal
Department of Chemistry , Indian Institute of Technology Madras , Chennai 600036 , India . Email:
Department of Chemistry , Brown University , Providence , Rhode Island 02912 , USA . Email:
Chem Sci. 2018 Jan 11;9(7):1976-1981. doi: 10.1039/c7sc05014c. eCollection 2018 Feb 21.
Among the series of stable -borate dianions, [B H ], the X-ray crystallographic structure of [BH] was determined only in 2011. To explore its chemistry and stability, we have isolated and structurally characterized two new transition metal complexes of the heptaborane, [(CpM)BH] (Cp = η-CH; M = Zr or Hf). The structures of [(CpM)BH] contain a pentagonal bipyramidal B core, coordinated by two {CpM} and two {BH} units equatorially. Structural and spectroscopic characterizations and DFT calculations show that [(CpM)BH] complexes are substantially more stable than the parent dianion, in either [BH] or ( BuN)[BH]. Our theoretical study and chemical bonding analyses reveal that the surprising stability of the two new heptaborane metal complexes is due to multi-center covalent bonds related to the two -{CpM} units, as well as electrostatic interactions between the {CpM} units and the B core. The facile syntheses of the heptaborane metal-complexes will allow further exploration of their chemistry.
在一系列稳定的硼酸盐二价阴离子[B₇H₇]²⁻中，[B₇H₇]²⁻的X射线晶体结构直到2011年才得以确定。为了探究其化学性质和稳定性，我们分离并通过结构表征了两种新的七硼烷过渡金属配合物[(CpM)₂B₇H₇]（Cp = η⁵-C₅H₅；M = Zr或Hf）。[(CpM)₂B₇H₇]的结构包含一个五角双锥硼核，由两个{CpM}单元和两个{BH}单元在赤道平面配位。结构和光谱表征以及密度泛函理论（DFT）计算表明，[(CpM)₂B₇H₇]配合物比母体二价阴离子在[B₇H₇]²⁻或(ⁿBu₄N)₂[B₇H₇]中要稳定得多。我们的理论研究和化学键分析表明，这两种新的七硼烷金属配合物令人惊讶的稳定性归因于与两个{CpM}单元相关的多中心共价键，以及{CpM}单元与硼核之间的静电相互作用。七硼烷金属配合物的简便合成将有助于进一步探索它们的化学性质。
