Structure Investigations of Group 13 Derivatives of N-Phenylsalicylideneimine

Abstract

The reaction of MMe3 with 1 molar equiv of N-phenylsalicylideneimine (HsaldPh) yields the O,N-chelate complexes Me2M(saldPh) (where M = Al (1), Ga (2), In (3)) in high yields. The reaction of 1 with γ-picoline results in a ligand redistribution reaction and the formation of the five-coordinate complex MeAl(saldPh)2 (4), while the gallium and indium compounds are stable in the presence of γ-picoline. The resulting compounds have been characterized in a solution by NMR and IR spectroscopy and cryoscopic molecular weight measurements, and their molecular and crystal structure have been determined by X-ray crystallography. Compounds 1 and 2 exist as monomeric tetrahedral complexes, while the indium analogue 3 is dimeric with the In2(μ-O)2 bridges and five-coordinate metal centers. The five-coordinate methylaluminum compound 4 exhibits trigonal-bipyramidal geometry of the metal center. The obtained results show that a Schiff base acts as a strongly coordinating chelate ligand and, in this regard, it resembles the symmetrical acetylacetonato ligand and related β-diketonates. An extended crystal structure analysis reveals that the isostructural crystalline complexes 1 and 2 comprise monomeric four-coordinate molecules linked by C−Himino···O hydrogen bonds, forming helical chains. Parallel left- and right-handed helices joined by C−H···π interactions give rise to the 3D extended tetragonal framework, with voids filled by solvent molecules. In the crystalline complex 4 the C−Haryl···O hydrogen bonds organize molecules into H-bonded dimers.

Synthesis and characterization of aluminum complexes of 2-pyrazol-1-yl-ethenolate ligands

“…The geometry at the aluminum atom is a distorted tetrahedron with angles ranging from 94.81(13)°t o 114.9(2)°. The most acute angle is associated with the bite angle of the chelate ligand, which is close to corresponding those in ½Et 2 AlfOCðMeÞCHCðMeÞN-ð2; 6-Pr i 2 C 6 H 3 Þg [94.56 (9)°] [13] and [Et 2 Al{Sal(Bu t )}] [94.97 (6)°] [14]. The Al1-N1 distance of 1.940(3) Å is a little shorter than those found in ½R 2 AlfOCðMeÞCHC-ðMeÞNð2; 6-Pr i 2 C 6 H 3 Þg (R = Me, 1.954(6) Å ; R = Et, 1.958(2) Å ) [15] and in [Et 2 Al{Sal(Bu t )}] (1.976(2) Å ) [16].…”

“…Ligand redistributions often occur between aluminum complexes. A number of examples have been reported in the literature [11][12][13]. In addition, attempts to prepare complex 7 by reaction of 3 with an equiv of MeAlCl 2 were unsuccessful.…”

“…Calc. for C 13 : d 30.41, 30.70, 31.38, 32.05, 57.95, 100.82, 128.12, 128.93, 133.75, 135.21, 152.21, 160.85, 193.75. IR: m C@O 1699 cm À1 .…”

“…1 H NMR (C 6 D 6 ): d 0.10 (s, 6H, AlMe 2 ), 1.11 (s, 9H, Bu t ), 1.41 (s, 9H, Bu t ), 6.02 (s, 1H, CH), 7.01 (s, 1H, CH), 7.22-7.34 (m, 3H, Ph), 2H,Ph). 13 C NMR (C 6 D 6 ): d 1. 42, 28.94, 30.98, 31.69, 32.62, 100.62, 102.77, 125.76, 128.17, 128.71, 128.88, 138.44, 150.09, 152.36, 161.33. 3.6.…”

“…1 H NMR (C 6 D 6 ): d 0.48-0.89 (m, 4H, AlCH 2 ), 1.49 (s, 3H, Me), 1.50 (t, J = 8.1 Hz, 6H, Me), 2.14 (s, 3H, Me), 5.35 (s, 1H, CH), 6.27 (s, 1H, CH), 7.24-7.35 (m, 3H, Ph), 7.96-7.99 (m, 2H, Ph). 13 C NMR (C 6 D 6 ): d 0. 99, 9.50, 10.48, 12.25, 96.76, 106.34, 125.72, 128.55, 128.69, 138.62, 139.37, 146.48, 149.92.…”