Bond order for #"NO"^+#Order by bond size: # "NO"#, # "NO "^(+)#, #"NO "^ (- )#Is #"CARBON MONOXIDE"# a Lewis acid? #" O"_ 2 # is popular to be paramagnetic, and also it is just one of the successes of molecular orbital concept. You can see that #"CARBON MONOXIDE"# is not (as it has absolutely no unpaired electrons), yet #"NO"# is (it has one unpaired electron).

Well, the MO layout for #"O"_ 2 # is:

*

* The bond order is currently determined in the representation.

The bonding electrons remain in the #sigma _(twos)#, #sigma _(2p)#, #pi _(2p_x)#, and also #pi _(2p_y)# MOs, offering # 2 +2 +2 +2 = 8 #.

The typo on the #sigma _(twos)^"*"# in the representation must be remedied, as well as later on, the antibonding electrons remain in the #sigma _(twos)^"*"#, #pi _(2p_x)^"*"#, as well as #pi _(2p_y)^"*"# MOs, providing # 2 +1 +1 = 4 #.

#"BO" = 1/2("bonding e"^(-) - "antibonding e"^(-))##= 1/2(2 +2 +2 +2 - 2 - 1 - 1) = shade(blue)( 2 )#What we need to discuss is that the bond order is meant to be # 2 #. Besides, it"s a dual bond...

#: ddot"O"=ddot"O": #The MO representation for #" CARBON MONOXIDE"# is: The bonding MOs are the # 2sigma #, # 1pi_x #, # 1pi_y #, as well as # 3sigma #, which offers # 2 +2 +2 +2=8 # bonding electrons. The antibonding MO is the # 2sigma ^" *"#, which provides # 2 # antibonding electrons. Thus, the bond order right here is:

#"BO" = 1/2("bonding e"^(-) - "antibonding e"^(-))##= 1/2(2 +2 +2 +2 -2) = shade(blue)( 3 )#And this is reasonable ... #"CARBON MONOXIDE"# has a three-way bond...

#:"C"-="O": ##"CARBON MONOXIDE"# has # 14 # electrons, while #"NO"^(+)# has # 14 # electrons (obtained one by #"C" -> "N"# and also shed one by #"NO" -> "NO"^(+) + e ^(-)#), so #"NO"^(+)# as well as #"CARBON MONOXIDE"# are isoelectronic.

#:"C"-="O": ##:"N"-="O": ^(+)#Hence, the bond order of #"NO"# is either # 2.5 # or # 3.5 #, depending upon whether the last electron entered into a bonding or antibonding MO.

. The MO layout of #"NO"# is:

*

The last electron remains in truth in the # 2b_1 # antibonding MO, so the bond order of #"NO"# has actually lowered by # 1/2 # about #"NO"^(+)# or #"CARBON MONOXIDE"#.

Consequently the bond order is #color(blue)( 2.5 )#. That represents the Lewis framework of:

#: populate"N"=ddot"O": #with a vibration crossbreed framework of:

#""^(( -0.5 )): populate"N"stackrel("- -"shade(white)(.))(=)dot"O": ^(( +0.5 )#And this undoubtedly reveals # 2.5 # bonds, as one electron is cooperated a fifty percent-#pi #-bond.