Order by bond length? #"NO"#, #"NO"^(+)#, #"NO"^(-)#
1 Answer
The bond strength increases going from
#r_("N"-"O")^("NO"^(-)) > r_("N"-"O")^("NO") > r_("N"-"O")^("NO"^(+))#
To start with,
#color(red)(["*"])# - except for the orbital ordering below the#pi^"*"# (the#2b_1,2b_2# ) of these species
To prove this, here is the MO diagram of
(The original was this; I added the orbital depictions and symmetry labels.)
Quick overview of what the labels correspond to what MOs:
#1a_1# is the#sigma_(2s)# bonding MO.#2a_1# is the#sigma_(2s)^"*"# antibonding MO.#1b_1# is the#pi_(2p_x)# bonding MO.#1b_2# is the#pi_(2p_y)# bonding MO.#3a_1# is the#sigma_(2p_z)# bonding MO, but it's relatively nonbonding with respect to oxygen.#2b_1# is the#pi_(2p_x)^"*"# antibonding MO.#2b_2# is the#pi_(2p_y)^"*"# antibonding MO.#4a_1# is the#sigma_(2p_z)^"*"# antibonding MO.
Note that for
#"NO"^(+)# has#bb0# #pi^"*"# antibonding electrons.#"NO"# has#bb(1)# #pi^"*"# antibonding electron.#"NO"^(-)# has#bb(2)# #pi^"*"# antibonding electrons.
As the number of antibonding electrons increases, the
Thus, the bond strength increases going from