Synthesis and crystal structures of trimethylindium adducts with bidentate and macrocyclic tertiary amines

The structures of trimethylindium (Me₃In) adducts with the bidentate tertiary amine N,N,N′,N′-tetramethyl-4,4′-methylenebis(aniline)[MBDA] and the macrocyclic amines 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane [N₄-aza crown] and 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane [N₆-aza crown] have been determined by single crystal X-ray diffraction. The adducts have the following stoichiometries, Me₃In·2MBDA 1, 2Me₃In·MBDA 2, 4Me₃In·N₄-aza crown 3 and 6Me₃In·N₆-aza crown 4. Compound 1 contains five-coordinate Me₃In in a trigonal bipyramidal configuration and displays the longest In-N bond lengths yet reported (2.720(4), 2.865 Å); 2-4 contain four-coordinate Me₃In molecules in a tetrahedral configuration. Compounds 1-4 can be used as intermediate adducts in the adduct purification of Me₃In for use in the MOVPE (metal organic vapour phase epitaxy) of InP and related III-V semiconductors.