Tetraaza Macrocycles as Ancillary Ligands in Early Metal Alkyl Chemistry. Synthesis and Characterization of Out-of-Plane (Me4taen)ZrX2 (X = alkyl, benzyl, NMe2, Cl) and (Me4taen)ZrX2(NHMe2) (X = Cl, CCPh) Complexes

Black, David G.; Swenson, Dale C.; Jordan, Richard F.; Rogers, Robin D.

doi:10.1021/om00007a062

Cited by 75 publications

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“…The d-transition metal complexes of 6,8,15,17-tetramethyldibenzotetraaza [14]-annulene, abbreviated tmtaaH 2 , whose systematic name is 7,16-dihydro-6,8,15,17-tetradecine, have been extensively developed since this ligand became available in synthetically useful amounts. [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 .…”

Section: Introductionmentioning

confidence: 99%

“…[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%

“…For example, the zirconium derivatives of the type (tmtaa)ZrX 2 , (cot)ZrX 2 , (porph)ZrX 2 have been studied as electronically altered analogues of Cp 2 ZrX 2 . [9][10][11][12][13][14] In addition, the diamagnetic complexes Zr(cot) 2 , Zr(porph) 2 and Zr(pc) 2 with a d 0 electronic configuration are known. 11, 15-20 50 70 The binary f-transition metal complexes of cot 2-, porph 2-and pc 2-are known only for cerium, [21][22][23][24][25] but Ce(tmtaa) 2 is unknown.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2006

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“…There Selected bond angles (°) [4]. Lithium atoms in this coordination environment are relatively rare [13][14][15][16]. The closest structurally related compounds are lithium salts of tetraaza macrocycles, Li 2 [tmtaa](DME) 3 [16], and [Li(thf) 2 ] 2 [Me 4 taen] [14] which show a N 4 macrocycle capped on each side by an ether-coordinated lithium atom, though the degree and symmetry of coordination of the lithium to the four nitrogens vary considerably.…”

Section: Resultsmentioning

confidence: 99%

“…Lithium atoms in this coordination environment are relatively rare [13][14][15][16]. The closest structurally related compounds are lithium salts of tetraaza macrocycles, Li 2 [tmtaa](DME) 3 [16], and [Li(thf) 2 ] 2 [Me 4 taen] [14] which show a N 4 macrocycle capped on each side by an ether-coordinated lithium atom, though the degree and symmetry of coordination of the lithium to the four nitrogens vary considerably. In Li 2 [tmtaa](DME) 3 , the N 4 the ether-bonded lithium atom sits closer to the macrocycle plane, a fact that is reflected in the shorter Li-N distances (Li-N 2.028(6) Å 2.177(6) Å, 2.038(6) Å, 2.070(7) Å) and longer Li- The porphyrin plane in Li 2 TPP(Et 2 O) 2 is slightly ruffled with the maximum deviation from planarity being 0.09 Å and the pyrroles being tilted 3.5 and 2.6° with respect to the porphyrin plane.…”

Section: Resultsmentioning

confidence: 99%

Ionic versus Covalent Bonding in Dilithium Porphyrins: X-ray Structure of Dilithium Tetraphenylporphyrin Bis(etherate)

Dawson

Arnold

1997

J. Porphyrins Phthalocyanines

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The solid state structure of dilithium tetraphenylporphyrin bis(etherate) has been determined by X-ray crystallography. The structure shows the lithium atoms are displaced out of the plane of the porphyrin, each coordinated in a square pyramidal fashion to the four nitrogen atoms in addition to a molecule of diethyl ether. The lithium atoms are identical, as required by the crystallographic inversion centre. X-ray data are as follows: [Formula: see text] (# 2) with a = 10.1908(4) Å, b = 11.6553(4) Å, c = 12.5199(5) Å, α = 111.644(1)°, β = 98.029(1)°, γ = 111.883(1)°, V = 1214.61(9)Å3, dcalc = 1.171 g cm -3 and Z = 1.

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Formation and Structures of [1,2–Bis(N-tert-butylcarbamoyl)cyclopentadienyl]zirconium Complexes – Coordination Chemistry of a “Fulvenologous” Malonic Amide Anion Ligand System

Klaß¹,

Duda²,

Kleigrewe³

et al. 1999

Eur. J. Inorg. Chem.

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Treatment of sodium cyclopentadienide with two molar equivalents of tert‐butyl isocyanate yields sodium 1,2‐bis(N‐tert‐butylcarbamoyl)cyclopentadienide (6). The [C5H3(1,2‐CONHCMe3)2]Na reagent 6 adds to Cp2Zr(CH3)Cl (8) to yield Cp2Zr(CH3)[C5H3(CONHCMe3)2] (9). In 9 the C5H3(CONHCMe3)2 ligand is bonded to zirconium through one of its carboxamido‐oxygen atoms (ĸO‐coordination). Treatment of 6 with CpZrCl3(THF)2 yields CpZrCl2[C5H3(CONHCMe3)2](THF) 11. In 11 the 1,2‐bis(N‐tert‐butylcarbamoyl)cyclopentadienide moiety serves as a Cs‐symmetric chelate ligand, binding to zirconium through both carbamoyl oxygens (ĸ2O,O′‐coordination). The same seven‐membered metallacyclic structural type is found in the reaction products of 6 with ZrCl4(THF)2 in 1:1 and 2:1 molar ratios. The former yields the distorted octahedral complex ZrCl3[C5H3(CONHCMe3)2](THF) (12), the latter gives the chiral octahedral system ZrCl2[C5H3(CONHCMe3)2]2 (13). In solution, complex 13 undergoes a thermally induced enantiomerization process (Λ → Δ interconversion), for which a Gibbs activation energy of ΔG‡enant = 14.0 ± 0.3 kcal mol−1 was determined by dynamic 1H‐NMR spectroscopy. The ĸ2O,O′‐coordination of the [C5H3(1,2‐CONHCMe3]− ligand in the complexes 11, 12, and 13 was secured by X‐ray crystal structure analyses.

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Tetraaza Macrocycles as Ancillary Ligands in Early Metal Alkyl Chemistry. Synthesis and Characterization of Out-of-Plane (Me4taen)ZrX2 (X = alkyl, benzyl, NMe2, Cl) and (Me4taen)ZrX2(NHMe2) (X = Cl, CCPh) Complexes

Cited by 75 publications

References 0 publications

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

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

Ionic versus Covalent Bonding in Dilithium Porphyrins: X-ray Structure of Dilithium Tetraphenylporphyrin Bis(etherate)

Formation and Structures of [1,2–Bis(N-tert-butylcarbamoyl)cyclopentadienyl]zirconium Complexes – Coordination Chemistry of a “Fulvenologous” Malonic Amide Anion Ligand System

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