The structure of a compound with n atoms of this element will differ based on how much the (*) electron count deviates from 4n+2 electrons, differences in which will result in deltahedra with caps or vertices missing.
This element is bound to four fluorine substituted aryl groups in the first compound considered a non-coordinating anion. That anion containing this element serves as a counterion in Brookhart's acid. This element is found in the center of the first scorpionate ligands. Lipscomb's styx mnemonic counts the number of bonds in compounds containing this element. The structure of a compound with n atoms of this element will differ based on how much the (*) electron count deviates from 4n+2 electrons, differences in which will result in deltahedra with caps or vertices missing. Those configurations of this element can be termed hypho, arachno, closo, or nido. This element forms 2 electron bonds between 3 atoms, resulting in electron deficient clusters. A common example of a Lewis acid that isn't a Bronsted-Lowry acid is this element's trifluoride, which is trigonal planar due to only having 6 total valence electrons. For 10 points, name this element with atomic number 5.
This element is bound to four fluorine substituted aryl groups in the first compound considered a non-coordinating anion.
boron [or B]