“…Both the Al–O = 1.975(1) Å or Al1–O1 = 1.986(2) Å and Al1–O2 = 1.977(2) Å, (for 3a or 3b ) and the Al–Cl (2.232(1) Å) or Al1–Cl1 = 2.249(1) Å and Al1–Cl1 = 2.214(1) Å (for 3a or 3b , respectively) distances are slightly longer than those observed for the four-coordinate dimer 1a , and the axial Al1–N1 distances are 2.057(3) or 2.043(3) and Al1–N2 distances are 2.065(3) Å or 2.046(3) for 3a or 3b , respectively. Compounds 3a and 3b represent unique examples of monomeric aluminum carboxylates with a chelating carboxylate ligand (structurally characterized analogous gallium carboxylate was also reported very recently). It is worthy to note that our previous theoretical calculations on the relative stability of various structures of the type 3 adducts confirmed that the formation of the six-coordinate chelate structure is thermodynamically preferred which is in agreement with the experimental data …”
A series of dichloroaluminum carboxylates [Cl(2)Al(O(2)CR)](2) (were R = Ph (1a), (t)Bu (1b), CHCH(2) (1c) and C(11)H(23) (1d)) were prepared and extended investigations on their structure and reactivity toward various Lewis bases and H(2)O performed. Compounds [Cl(2)Al(O(2)CR)](2) and their adducts with Lewis bases show a large structural variety, featuring both molecular and ionic forms with different coordination numbers of the metal center and various coordination modes of the carboxylate ligand. Upon addition of a Lewis base of moderate strength the molecular form [Cl(2)Al(O(2)CR)](2) equilibrates with new ionic forms. In the presences of 4-methylpyridine the six-coordinate Lewis acid-base adducts [Cl(2)Al(λ(2)-O(2)CR)(py-Me)(2)] [R = Ph (3a), (t)Bu (3b)] with a chelating carboxylate ligand were formed. The reactions of 1a, 1b, and 1d with 0.33 equiv of H(2)O in THF-toluene solution lead to oxo carboxylates [(Al(3)O)(O(2)CR)(6)(THF)(3)] [AlCl(4)] [where R = Ph (4a(THF)), (t)Bu (4b(THF)), and C(11)H(23) (4d(THF))] in high yield. The similar reaction of 1c in tetrahydrofuran (THF) afforded the chloro(hydroxo)aluminum acrylate [(ClAl)(2)(OH)(O(2)CC(2)H(3))(2) (THF)(4)][AlCl(4)] (5), while the hydrolysis of 1b in MeCN lead to the hydroxoaluminum carboxylate [Al(2)(OH)(O(2)C(t)Bu)(2)(MeCN)(6)][AlCl(4))(3)] (6). All compounds were characterized by elemental analysis, (1)H, (27)Al NMR, and IR spectroscopy, and the molecular structure of 1a, 3a, 3b, 4a(THF), 4b(THF), 4b(py-Me'), 5, and 6 were determined by single-crystal X-ray diffraction. The study provides a platform for testing transformations of secondary building units in Al-Metal-Organic Frameworks toward H(2)O and neutral donor ligands.
“…Both the Al–O = 1.975(1) Å or Al1–O1 = 1.986(2) Å and Al1–O2 = 1.977(2) Å, (for 3a or 3b ) and the Al–Cl (2.232(1) Å) or Al1–Cl1 = 2.249(1) Å and Al1–Cl1 = 2.214(1) Å (for 3a or 3b , respectively) distances are slightly longer than those observed for the four-coordinate dimer 1a , and the axial Al1–N1 distances are 2.057(3) or 2.043(3) and Al1–N2 distances are 2.065(3) Å or 2.046(3) for 3a or 3b , respectively. Compounds 3a and 3b represent unique examples of monomeric aluminum carboxylates with a chelating carboxylate ligand (structurally characterized analogous gallium carboxylate was also reported very recently). It is worthy to note that our previous theoretical calculations on the relative stability of various structures of the type 3 adducts confirmed that the formation of the six-coordinate chelate structure is thermodynamically preferred which is in agreement with the experimental data …”
A series of dichloroaluminum carboxylates [Cl(2)Al(O(2)CR)](2) (were R = Ph (1a), (t)Bu (1b), CHCH(2) (1c) and C(11)H(23) (1d)) were prepared and extended investigations on their structure and reactivity toward various Lewis bases and H(2)O performed. Compounds [Cl(2)Al(O(2)CR)](2) and their adducts with Lewis bases show a large structural variety, featuring both molecular and ionic forms with different coordination numbers of the metal center and various coordination modes of the carboxylate ligand. Upon addition of a Lewis base of moderate strength the molecular form [Cl(2)Al(O(2)CR)](2) equilibrates with new ionic forms. In the presences of 4-methylpyridine the six-coordinate Lewis acid-base adducts [Cl(2)Al(λ(2)-O(2)CR)(py-Me)(2)] [R = Ph (3a), (t)Bu (3b)] with a chelating carboxylate ligand were formed. The reactions of 1a, 1b, and 1d with 0.33 equiv of H(2)O in THF-toluene solution lead to oxo carboxylates [(Al(3)O)(O(2)CR)(6)(THF)(3)] [AlCl(4)] [where R = Ph (4a(THF)), (t)Bu (4b(THF)), and C(11)H(23) (4d(THF))] in high yield. The similar reaction of 1c in tetrahydrofuran (THF) afforded the chloro(hydroxo)aluminum acrylate [(ClAl)(2)(OH)(O(2)CC(2)H(3))(2) (THF)(4)][AlCl(4)] (5), while the hydrolysis of 1b in MeCN lead to the hydroxoaluminum carboxylate [Al(2)(OH)(O(2)C(t)Bu)(2)(MeCN)(6)][AlCl(4))(3)] (6). All compounds were characterized by elemental analysis, (1)H, (27)Al NMR, and IR spectroscopy, and the molecular structure of 1a, 3a, 3b, 4a(THF), 4b(THF), 4b(py-Me'), 5, and 6 were determined by single-crystal X-ray diffraction. The study provides a platform for testing transformations of secondary building units in Al-Metal-Organic Frameworks toward H(2)O and neutral donor ligands.
“…An intriguing case of the dormant Lewis acidity is associated with the chemistry of dichloroaluminium 4 and dichlorogallium 5 carboxylates. These compounds react with Lewis bases to form a large structural variety of adducts ranging from molecular complexes to ionic species exhibiting different coordination numbers of the metal centres and various coordination modes of carboxylate ligands (Scheme 1).…”
The octet-compliant group 13 organometallics with highly polarized bonds in the metal coordination sphere exhibit a significant tendency to maximize their coordination number through the formation of adducts with a wide range of neutral donor ligands or by self-association to give aggregates containing tetrahedral and higher coordinated aluminium centres, and even in some cases molecular complexes equilibrate with ionic species of different coordination numbers of the metal centre. This work provides a comprehensive overview of the structural chemistry landscape of the group 13 carboxylates. Aside from a more systematic approach to the general structural chemistry of the title compounds, the structure investigations of [RM(μ-OCPh)]-type benzoate complexes (where M = B, Al and Ga) and their Lewis acid-base adducts [(RM)(μ-OCPh)(py-Me)] are reported. DFT calculations were also performed to obtain a more in-depth understanding of both the changes in the bonding of group 13 organometallic carboxylate adducts with a pyridine ligand.
“…The literature concerning reactions of group 13 organometallic carboxylates with Lewis bases is very limited. Simple Lewis acid–base adducts between a mononuclear group 13 organometallic carboxylate moiety and Lewis base are lacking, and only very recently, the first dichloroaluminum and gallium adducts with γ-picoline (py-Me), [Cl 2 M(λ 2 -O 2 CPh)(py-Me) 2 ], which feature a nonbridging and M-chelating carboxylate ligand, were reported . Similarly, the indium homologue forms [Cl 2 In-(λ 2 -O 2 CPh)(py-Me) 2 ] .…”
A family of group 13 organometallic macrocyclic phthalates [(MMe2)2(μ-O2C)2-1,2-C6H4]2 (where M = Al (1), Ga (2), In (3)) is prepared, and the reactivity of these homologous carboxylates toward various monodentate Lewis bases is investigated. The studies provide the first structurally characterized methylindium [{(Me2In)(μ-O2C)2-1,2-C6H4}{Me2In(THF)}]n (4) and methylaluminum [{(Me2Al)(μ-O2C)2-1,2-C6H4}{Me2Al(py-Me)}]n (5) 1D coordination polymers stabilized by dicarboxylate ligands as a result of disruption of the parent tetranuclear macrocyclic structural motifs in 3 and 1 by the incoming donor ligands. The molecular and crystal structures of the reported compounds are examined by spectroscopic studies and single-crystal X-ray diffraction.
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