▁basic ▁P ▁atom ; ▁in ▁the ▁case ▁of ▁Mes N 3 , ▁the ▁az ide ▁evol ves ▁N 2 ▁to ▁form ▁a ▁nit rene , ▁which ▁then ▁inser ts ▁into ▁a ▁C - H ▁bond ▁of ▁an ▁ar ene ▁subst itu ent ▁and ▁coordinates ▁to ▁P b ▁as ▁a ▁Lewis ▁base . ▁ ▁Insert ion ▁ ▁Similar ▁to ▁car ben es ▁and ▁other ▁Group ▁ 1 4 ▁con gen ers , ▁pl um by len es ▁have ▁been ▁shown ▁to ▁under go ▁insert ion ▁re actions , ▁specifically ▁into ▁C – X ▁( X ▁= ▁Br , ▁I ) ▁and ▁Group ▁ 1 6 ▁E – E ▁( E ▁= ▁S , ▁Se ) ▁b onds . ▁▁ ▁Insert ions ▁into ▁lead - subst itu ent ▁b onds ▁can ▁also ▁occur . 2 7 ▁In ▁the ▁examples ▁below , ▁insert ion ▁is ▁accompanied ▁by ▁intr am ole cular ▁re arr ang ement ▁to ▁place ▁more ▁electron - don ating ▁heter o at oms ▁next ▁to ▁the ▁electron - def ic ient ▁lead . 2 7 ▁ ▁Trans met all ation ▁ ▁Pl um by len es ▁are ▁known ▁to ▁under go ▁nucle oph il ic ▁substitution ▁with ▁organ omet all ic ▁re ag ents ▁to ▁form ▁trans met all ated ▁products . 2 8 ▁In ▁an ▁unusual ▁example , ▁the ▁use ▁of ▁T l PF 6 , ▁bearing ▁the ▁weak ly ▁coordin ating ▁an ion ▁P F 6 − , ▁led ▁to ▁the ▁formation ▁of ▁cry st als ▁of ▁an ▁o lig on