Structure relations between the four-coordinate, S = 1, macrocyclic complex, [Fe(C22H22N4)], and the neutral ligand, C22H24N4

Goedken, Virgil L.; Pluth, J. J.; Peng, Shie‐Ming; Bursten, Bruce E.

doi:10.1021/ja00441a023

Cited by 114 publications

(56 citation statements)

References 21 publications

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“…The saddle shape of the free ligand (Goedken, Pluth, Peng & Bursten, 1976) is retained in the metal complex ( Fig. 1), with the Ga atom replacing the two H atoms of the two NH groups in the ligand.…”

Section: (I) (Ll)mentioning

confidence: 99%

Structure of the monomethylgallium derivative of TMTAA (dibenzotetramethyltetraaza[14]annulene)

Alcock¹,

Blacker²,

Errington³

et al. 1993

Acta Crystallogr C

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Section: (I) (Ll)mentioning

confidence: 99%

Structure of the monomethylgallium derivative of TMTAA (dibenzotetramethyltetraaza[14]annulene)

Alcock¹,

Blacker²,

Errington³

et al. 1993

Acta Crystallogr C

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“…[1][2][3][4][5] The [14]annulene nomenclature is informative since it connects tmtaaH 2 to two related classes of ligands that have an extensive chemistry, viz., [8]-annulene, otherwise known as cyclooctatetraene, cot, and [16]-annulenes, the porphyrins, porphH 2 , and phthalacyanines, pcH 2 . Although all of these ligands form stable dianions, their electronic structure and therefore the electronic properties of their complexes are different.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and magnetic properties of cerium macrocyclic complexes with tetramethyldibenzotetraaza[14]annulene, tmtaaH2

2006

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3 and tmtaaH 2 , the macrocyclic ligand 6,8,15,17-tetramethyldibenzotetraaza[14]annulene, depending on the stoichiometry, solvent and temperature. The crystal structure of Ce(tmtaa) 2 is isostructural with Zr(tmtaa) 2 , however magnetic susceptibility measurements in the range 5-300 K show that Ce(tmtaa) 2 is not diamagnetic, but is a temperature-independent paramagnet (TIP), similar to Ce(cot) 2 , cerocene. 2 , and phthalacyanines, pcH 2 . Although all of these ligands form stable dianions, their electronic structure and therefore the electronic properties of their complexes are different. The tmtaa 2-is a 24 π-electron system (4nπ, n= 6) that is not Hückel aromatic. The negative charge is not delocalized over its entire framework, but is localized on the four nitrogen atoms, that carry a total negative charge of -0.98 e, and the two β-carbon atoms in the imidinate ring that carry a -0.24 e charge, NC α (Me)C β (H)C α (Me)N. 6,7 The tmaa 2-is therefore not planar but is saddle shaped with idealized C 2v symmetry. 8 The cot 2-(4nπ+2, n=2) and porph 2-(4nπ+2, n=6) are aromatic and the negative charge is delocalized over the planar rings. Pr, Nd, Sm, Gd, Tb, Er and Yb. 30 In this paper the synthesis and physical properties of Ce(tmtaa) 2 and related complexes are described. Results and Discussion Synthesis and StructureThe synthesis of the complexes involves the reaction of tmtaaH 2 with Ce[N(SiMe 3 ) 2 ] 3 in various molar ratios. Proton transfer reactions of Ce[N(SiMe 3 ) 2 ] 3 , the pK a of (Me 3 Si)NH in thf is 26, 31 depend critically on the solvent, concentration of the reactants, and temperature. These details are given in the Experimental Section, which are reproducable when close attention to detail is observed, and shown schematically in Scheme 1. Solutions of complexes Ce(tmtaa)(tmtaaH) (1) and Ce 2 tmtaa 3 (2) are extremely sensitive to trace amounts of air, which result in formation of Ce(tmtaa) 2 (3), which is stable to air and moisture. Deliberate oxidation of either 1 or 2 is therefore an excellent synthetic route to 3.Ce(tmtaa)(tmtaaH) (1) not when Ln = Ce. Crystals of Ce(tmtaa)(tmtaaH) grown from toluene, were twinned, the tmtaa and tmtaaH fragments are disordered, and therefore the X-ray diffraction pattern could not be resolved. However, the 2:1 stoichiometry of the complex is confirmed. Ce(tmtaa)(tmtaaH) (1) decomposes slowly to Ce(tmtaa) 2 (3) and tmtaaH 2 (ratio 1:1) in C 6 D 6 at 65 °C over 14 days. Close inspection of the decomposition process reveales that after one day small amounts of Ce 2 (tmtaa) 3 (2) and tmtaaH 2 are detected in the 1 H NMR spectrum. Over the time priod of two weeks the resonances due to 2 increase then decrease as 3 is formed and the resonances due to tmtaaH 2 continue to increase until a steady state is reached. The decomposition does not eliminate hydrogen since the latter is not observed in the 1 H NMR spectrum and the addition of dehydroanthracene does not yield anthracene. It seems reasonable to suggest that the initial decomposition step of 1 is the format...

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“…The average benzenoid C--N distance is 1.417 (5)~,, compared to 1.404 (8)A for the free ligand (Goedkin, Pluth, Peng & Bursten, 1976 In ( The data were collected with the crystal mounted in a Lindemarm tube, held at 220 K with an Oxford Cryosystem Cryostream Cooler (Cosier & Glazer, 1986). Data collection and cell refinement: Siemens R3m system.…”

Section: Commentmentioning

confidence: 99%

Monochloroindium derivative of tmtaa (dibenzotetramethyltetraaza[14]annulene), [In(C22H22N4)Cl]

Phillips¹,

McCamley²,

Alcock³

et al. 1994

Acta Crystallogr C

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Structure relations between the four-coordinate, S = 1, macrocyclic complex, [Fe(C22H22N4)], and the neutral ligand, C22H24N4

Cited by 114 publications

References 21 publications

Structure of the monomethylgallium derivative of TMTAA (dibenzotetramethyltetraaza[14]annulene)

Structure of the monomethylgallium derivative of TMTAA (dibenzotetramethyltetraaza[14]annulene)

Synthesis and magnetic properties of cerium macrocyclic complexes with tetramethyldibenzotetraaza[14]annulene, tmtaaH2

Monochloroindium derivative of tmtaa (dibenzotetramethyltetraaza[14]annulene), [In(C22H22N4)Cl]

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