1,8‐Bis(borylamido)naphthalene Complexes of Lithium and Zinc(II) Including a Zinc(II) Isocyanide Adduct

The zinc coordination chemistry of a useful metal ion chelator, bis(borylamido)naphthalene ligand [1,8‐C 10 H 6 (NBNL) 2 ] 2– , which has two borylamido groups on a rigid naphthalene backbone, is presented. Deprotonation of N 1 ,N 8 ‐di(9‐bora‐bicyclo[3.3.1]nonan‐9‐yl)naphthalene‐1,8‐diamine, [1,8‐C 10 H 6 (NBNL) 2 ]H 2 ( 3 ) with two equivalents of n BuLi in Et 2 O afforded the lithium derivative, Li 2 (Et 2 O) 2 [1,8‐C 10 H 6 (NBNL) 2 ] ( 4 ). Metathesis reaction of Li 2 (Et 2 O) 2 [1,8‐C 10 H 6 (NBNL) 2 ] with ( t Bu 2 bipy)ZnCl 2 ( t Bu 2 bipy = 4,4′‐di‐ tert ‐butyl‐2,2′‐bipyridine) in a 1:1 molar ratio gave [1,8‐C 10 H 6 (NBNL) 2 ]Zn( t Bu 2 bipy) ( 5 ), which features an all‐nitrogen coordination sphere at zinc. The reaction of 4 with ZnCl 2 , however, produced [1,8‐C 10 H 6 (NBNL) 2 ]Zn(Et 2 O)(µ‐Cl)Li(Et 2 O) 3 ( 6 ), which retains one of the chlorides as ClLi(Et 2 O) 3 on zinc. Treatment of 6 with t Bu 2 bipy or two equivalents of 2,6‐dimethylphenyl isocyanide completes the salt elimination and led to [1,8‐C 10 H 6 (NBNL) 2 ]Zn( t Bu 2 bipy) ( 5 ) or [1,8‐C 10 H 6 (NBNL) 2 ]Zn(CNC 6 H 3 ‐2,6‐Me 2 ) 2 ( 7 ), respectively. Compounds 3 – 7 have been characterized by several analytical methods including X‐ray crystallography. The zinc atoms of 5 – 7 are four‐coordinate and adopt a distorted tetrahedral geometry. The ν (NC) bands of 7 in the IR spectrum have been observed at 2203 and 2187 cm –1 .