New Coordination Modes of Substituted Benzohydroxamic Acid with Dialkyltin(IV): Structural Diversity through Ligand Isomerization

When R 2 SnCl 2 (R = Me, n Bu) reacted with substituted benzohydroxamic acid (substituent = 4‐F; 2,4‐Cl 2 ; 2,5‐F 2 ) and potassium hydroxide in aqueous methanol solution, two types of condensation products could be obtained, depending on the molar ratio R 2 SnCl 2 /RCONHOH/KOH. When a 1:1:2 molar ratio was used, 1:1 alkyltin hydroxamates {( n ‐C 4 H 9 ) 2 Sn[4‐FC 6 H 4 C(O)NO]} n ( 1 ) and {(CH 3 ) 2 Sn[2,5‐F 2 C 6 H 3 C(O)NO]} n ( 2 ) were formed. When a 1:2:2 ratio was used, another two unexpected 2:3 alkyltin hydroxamates, {(CH 3 ) 4 Sn 2 [(2,4‐Cl 2 C 6 H 3 C(O)NHO) 2 ][2,4‐Cl 2 C 6 H 3 C(O)NO]} n ( 3 ) and {( n ‐C 4 H 9 ) 4 Sn 2 [(4‐FC 6 H 4 C(O)NHO) 2 ][4‐FC 6 H 4 C(O)NO]} n ( 4 ), were obtained. All these complexes were characterized by elemental analysis, IR, 1 H, 13 C, 119 Sn NMR spectra and X‐ray diffraction analysis. The results indicated overall ( Z )‐iminol coordination mode in the hydroximic tautomeric form for 1 and 2 , and keto‐iminol mixed‐coordination mode including both in ( Z )‐hydroxamic and ‐hydroximic tautomeric forms for 3 and 4 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)