Plajer Alex J, Colebatch Annie L, Rizzuto Felix J, Pröhm Patrick, Bond Andrew D, García-Rodríguez Raúl, Wright Dominic S
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
Institut fuer Chemie und Biochemie, Freie Universitaet Berlin, Fabeckstr. 34-36, 14159, Berlin, Germany.
Angew Chem Int Ed Engl. 2018 May 28;57(22):6648-6652. doi: 10.1002/anie.201802350. Epub 2018 Apr 27.
Although a multitude of studies have explored the coordination chemistry of classical tripodal ligands containing a range of main-group bridgehead atoms or groups, it is not clear how periodic trends affect ligand character and reactivity within a single ligand family. A case in point is the extensive family of neutral tris-2-pyridyl ligands E(2-py) (E=C-R, N, P), which are closely related to archetypal tris-pyrazolyl borates. With the 6-methyl substituted ligands E(6-Me-2-py) (E=As, Sb, Bi) in hand, the effects of bridgehead modification alone on descending a single group in the periodic table were assessed. The primary influence on coordination behaviour is the increasing Lewis acidity (electropositivity) of the bridgehead atom as Group 15 is descended, which not only modulates the electron density on the pyridyl donor groups but also introduces the potential for anion selective coordination behaviour.
尽管众多研究已经探索了含有一系列主族桥头原子或基团的经典三脚架配体的配位化学，但尚不清楚周期趋势如何影响单个配体家族内的配体特性和反应性。一个恰当的例子是庞大的中性三（2-吡啶基）配体E(2-py)（E = C-R、N、P）家族，它们与原型三吡唑硼酸酯密切相关。有了6-甲基取代的配体E(6-Me-2-py)（E = As、Sb、Bi），就可以评估仅在元素周期表中同一族内桥头修饰的影响。对配位行为的主要影响是随着第15族元素的递降，桥头原子的路易斯酸性（电正性）增加，这不仅调节了吡啶基供体基团上的电子密度，还引入了阴离子选择性配位行为的可能性。
