Synthesis and characterisation of aluminium and magnesium complexes supported by pendant oxalic amidinate ligands

Abstract

Two pendant oxalic amidine compounds [C6H5N=C{NH(CH2)(2)OMe}-C{NH(CH2)(2)OMe} = NC6H5] (1) (oxam(OMe)(2)H-2) and [C6H5N=C{NH(CH2)(2)NMe2} - C{NH(CH2)(2)NMe2} = NC6H5] (2) (oxam(NMe2)(2)H-2) are described. Reactions of 1 or 2 with two molar equivalents of AlMe3 in toluene give the bimetallic complexes [(Me-2)Al(oxam(OMe)(2)) Al(Me-2)] (3) and [(Me-2)Al(oxam(NMe2)(2)) Al(Me-2)] (4), respectively. Treatment of 1 or 2 with two molar equivalents of MeMgBr in THF affords the bimetallic complexes [(Br)(THF) Mg(oxam(OMe)(2))Mg( THF)(Br)] (5) and [(Br)(THF) Mg(oxam(NMe2)(2)) Mg(THF)(Br)] (6) respectively. The crystal and molecular structures are reported for compounds 1, 2, 3, 5 and 6

The syntheses and structures of some main group complexes of the sterically hindered N,N′-bis(2,6-diisopropylphenyl)-4-toluamidinate ligand

“…Compound 3 was also prepared via salt elimination using dimethylaluminium chloride and 1 under similar conditions (see Scheme 1). The FTIR and 1 H, 13 C NMR spectra of solvent donor free 3 display DippAm stretches and resonances consistent with those for 1 and 2 (C-N stretches at 1612, 1576 cm À1 , Pr i methyl doublets at 1.09 and 1.39 ppm, virtual methyne septet at 3.75 ppm, discrete resonances maintained at 70 1C without coalescence) while the N CN backbone resonance is shifted upfield by ca. 20 ppm to 173.5 ppm.…”

“…1050 cm À1 , indicating the absence of included solvent. 1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor.…”

“…1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor. This arrangement invokes isopropyl methyl substituents with two separate chemical shifts (1; 1.20 and 1.30 ppm, 2; 1.16 and 1.34 ppm).…”

The syntheses and structures of some main group complexes of the sterically hindered N,N′-bis(2,6-diisopropylphenyl)-4-toluamidinate ligand

“…Compound 3 was also prepared via salt elimination using dimethylaluminium chloride and 1 under similar conditions (see Scheme 1). The FTIR and 1 H, 13 C NMR spectra of solvent donor free 3 display DippAm stretches and resonances consistent with those for 1 and 2 (C-N stretches at 1612, 1576 cm À1 , Pr i methyl doublets at 1.09 and 1.39 ppm, virtual methyne septet at 3.75 ppm, discrete resonances maintained at 70 1C without coalescence) while the N CN backbone resonance is shifted upfield by ca. 20 ppm to 173.5 ppm.…”

“…1050 cm À1 , indicating the absence of included solvent. 1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor.…”

“…1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor. This arrangement invokes isopropyl methyl substituents with two separate chemical shifts (1; 1.20 and 1.30 ppm, 2; 1.16 and 1.34 ppm).…”

N -aryloxide-amidinate group 4 metal complexes

“…For example, pyridinyl-, amino-, phenoxy (PhOMe)-amidine ligands were synthesized utilizing imine chloride, which reacted with a primary amine to yield the desired amidine. [16][17][18] Another method involves reacting substituted nitriles with N,N-disubstituted metal amides, typically for silylamine, which afforded pyridinyl-, furanyl-, and aminoamidine. [19][20][21][22][23] The most widely used reaction method involves the addition of an alkyl-/aryl-metal moiety to N,N′-disubstituted carbodiimide.…”

Synthesis and Reactivities of Guanidinate Dianion Complexes of Heterobimetallic Lanthanide−Lithium Cp2Ln[(CyN)2CNPh]Li(THF)3

“…Considerable interest has focused on the tailoring of two independent monoanion ligands to a defining and constraining linked dianion ligand for further perfecting the versatility of these ligands. Such concepts have been elegantly applied to ansa -metallocene complexes and other anionic functionalities including aryloxides, amidinates, amides, and imides . However, there are few reports employing linked diguanidinate dianion analogues .…”

The syntheses and structures of some main group complexes of the sterically hindered N,N′-bis(2,6-diisopropylphenyl)-4-toluamidinate ligand

“…Compound 3 was also prepared via salt elimination using dimethylaluminium chloride and 1 under similar conditions (see Scheme 1). The FTIR and 1 H, 13 C NMR spectra of solvent donor free 3 display DippAm stretches and resonances consistent with those for 1 and 2 (C-N stretches at 1612, 1576 cm À1 , Pr i methyl doublets at 1.09 and 1.39 ppm, virtual methyne septet at 3.75 ppm, discrete resonances maintained at 70 1C without coalescence) while the N CN backbone resonance is shifted upfield by ca. 20 ppm to 173.5 ppm.…”

“…1050 cm À1 , indicating the absence of included solvent. 1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor.…”

“…1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor. This arrangement invokes isopropyl methyl substituents with two separate chemical shifts (1; 1.20 and 1.30 ppm, 2; 1.16 and 1.34 ppm).…”

N -aryloxide-amidinate group 4 metal complexes

“…For example, pyridinyl-, amino-, phenoxy (PhOMe)-amidine ligands were synthesized utilizing imine chloride, which reacted with a primary amine to yield the desired amidine. [16][17][18] Another method involves reacting substituted nitriles with N,N-disubstituted metal amides, typically for silylamine, which afforded pyridinyl-, furanyl-, and aminoamidine. [19][20][21][22][23] The most widely used reaction method involves the addition of an alkyl-/aryl-metal moiety to N,N′-disubstituted carbodiimide.…”

Synthesis and Reactivities of Guanidinate Dianion Complexes of Heterobimetallic Lanthanide−Lithium Cp2Ln[(CyN)2CNPh]Li(THF)3

“…Considerable interest has focused on the tailoring of two independent monoanion ligands to a defining and constraining linked dianion ligand for further perfecting the versatility of these ligands. Such concepts have been elegantly applied to ansa -metallocene complexes and other anionic functionalities including aryloxides, amidinates, amides, and imides . However, there are few reports employing linked diguanidinate dianion analogues .…”

The syntheses and structures of some main group complexes of the sterically hindered N,N′-bis(2,6-diisopropylphenyl)-4-toluamidinate ligand

“…Compound 3 was also prepared via salt elimination using dimethylaluminium chloride and 1 under similar conditions (see Scheme 1). The FTIR and 1 H, 13 C NMR spectra of solvent donor free 3 display DippAm stretches and resonances consistent with those for 1 and 2 (C-N stretches at 1612, 1576 cm À1 , Pr i methyl doublets at 1.09 and 1.39 ppm, virtual methyne septet at 3.75 ppm, discrete resonances maintained at 70 1C without coalescence) while the N CN backbone resonance is shifted upfield by ca. 20 ppm to 173.5 ppm.…”

“…1050 cm À1 , indicating the absence of included solvent. 1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor.…”

“…1 H and 13 C NMR Spectra confirm this and, from singular NCN resonances located at 154.3 and 158.9 ppm (1 and 2 respectively, HDippAm; 141.5 ppm), infer the presence of a singular benzamidinate isomer in solution. Furthermore, for both 1 and 2, the number of aromatic singlets in the 13 C NMR spectra (8 for both) suggests symmetrical binding about the NCN donor. This arrangement invokes isopropyl methyl substituents with two separate chemical shifts (1; 1.20 and 1.30 ppm, 2; 1.16 and 1.34 ppm).…”

N -aryloxide-amidinate group 4 metal complexes

“…For example, pyridinyl-, amino-, phenoxy (PhOMe)-amidine ligands were synthesized utilizing imine chloride, which reacted with a primary amine to yield the desired amidine. [16][17][18] Another method involves reacting substituted nitriles with N,N-disubstituted metal amides, typically for silylamine, which afforded pyridinyl-, furanyl-, and aminoamidine. [19][20][21][22][23] The most widely used reaction method involves the addition of an alkyl-/aryl-metal moiety to N,N′-disubstituted carbodiimide.…”

Synthesis and Reactivities of Guanidinate Dianion Complexes of Heterobimetallic Lanthanide−Lithium Cp2Ln[(CyN)2CNPh]Li(THF)3

“…Considerable interest has focused on the tailoring of two independent monoanion ligands to a defining and constraining linked dianion ligand for further perfecting the versatility of these ligands. Such concepts have been elegantly applied to ansa -metallocene complexes and other anionic functionalities including aryloxides, amidinates, amides, and imides . However, there are few reports employing linked diguanidinate dianion analogues .…”