RE: isolobal vs. isoelectronic

["Shobe, Dave" <dshobe -AatT- sud-chemieinc.com>]

 From: Krzysztof Radacki [mailto:k.radacki -AatT- ic.ac.uk]
 > So he had argued that BH_3 has only one free orbital (not involved in
 > B-H bond) and CH_2 two of them. So BH_3 is isolobal to CH_3(+) but only
 > isoelectronic to CH_2.
 I would have said that all three (BH3, CH3+, and CH2) were isoelectronic
 since this is just a matter of counting electrons (8 e- and 6 valence e- in
 each case).  The # valence electrons has to be counted as well as the total,
 otherwise you reach conclusions such as Zn being "isoelectronic" to
 Ne3 and
 C5.
 However, CH2 would not be "isolobal" to BH3 or CH3+ because CH2 has a
 lone
 pair as well as an empty orbital.
 I forget the name for the relationship among for example {HCN, HSiP, HCAs,
 ...} where atoms are replaced by others in the same column of the periodic
 table.
 --David Shobe