Studies of Aryl Substituent and Solvent Donor Imposed Structural Diversity in N,N-Diarylformamidinate Complexes of Lithium

N,N′-Bis-Silylated Lithium Aryl Amidinates: Synthesis, Characterization, and the Gradual Transition of Coordination Mode from σ Toward π Originated by Crystal Packing Interactions

“…The Monomeric Supramolecular Structure. This packing arrangement, manifested in complexes 1 , 2 , 4 , and 12 from this work and four other published complexes, ,, corresponds to a monomeric structure in which no significant intermolecular forces that involve the amidinate core are present, as reflected by the intermolecular distance of about 4.7 Å for the above complexes. These complexes (Figures and ) also have very similar bond distances and angles (Table ).…”

N,N′-Bis-Silylated Lithium Aryl Amidinates: Synthesis, Characterization, and the Gradual Transition of Coordination Mode from σ Toward π Originated by Crystal Packing Interactions

“…The Monomeric Supramolecular Structure. This packing arrangement, manifested in complexes 1 , 2 , 4 , and 12 from this work and four other published complexes, ,, corresponds to a monomeric structure in which no significant intermolecular forces that involve the amidinate core are present, as reflected by the intermolecular distance of about 4.7 Å for the above complexes. These complexes (Figures and ) also have very similar bond distances and angles (Table ).…”

Chemoselectivity Diversity in the Reaction of LiNC6F5SiMe3with Nitriles and the Synthesis, Structure, and Reactivity of Zirconium Mono- and Tris[2-(2-pyridyl)tetrafluorobenzimidazolate] Complexes

“…Unlike the four signals in the room-temperature 19 F NMR spectrum of 3 in toluene-d 8 , which support the retention of its solid-state structure in solution at these conditions, there are only two fluorine signals in the 19 F NMR spectrum of 3 in THF-d 8 . 11 This higher symmetry about the tetrafluorinated ring (AB pattern) implies that a rapid rotation of the pyridine ring and Li-N(imidazolate) bond breaking and formation are operative.…”

“…We have recently reported the formation of coordination polymers of 3-and 4-pyridylamidinates, which resulted from the coordination of lithium centers to the pendant nitrogen atoms at the expense of TMEDA. 18 The displacement of TMEDA with THF in complex 3 is also supported by the almost identical 1 H and 19 F NMR spectra (pyridyl and tetrafluorophenylene regions, respectively) of 3 and 5 in THF-d 8 .…”

Lithium and sodium N,N′-di(2,6-dialkylphenyl)formamidinate complexes

“…This appears reasonable given their identical composition (by 1 H NMR). Thus, the addition of alkyl steric bulk to the 2-and 6-aryl positions of DME solvated lithium N,N 0 -di(aryl)formamidinates brings about a decrease in diazaallyl NCN angle (4(4-Me); 127.7(2)° [ 11], 5; 125.4(2)°, 6; 120.4(1)°), which is consistent with a transition from bridging to chelating amidinate donor. This permits a decrease in aryl:NCN plane and aryl:aryl plane torsion angles from FMes to FPhEt (4(4-Me); mean 66.6°and 87.2(1)°resp.…”

“…For sodium metallation, failure to isolate crystalline samples of 7 (empirical composition by 1 H NMR [Na(FXyl)(THF) 2 ]) leave its structural composition open to conjecture, however, the DME analogue (10) exists as a monomer in the solid state whilst the lack of asymmetry in 1 H NMR spectra of 7, as per 8, debases the possibility of aryl-C contacts. The lithiation of HFPhEt in DME renders a l 2 :g 1 :g 1 -bound dimer similar to less bulky N,N 0 -di(aryl)formamidinates [8,11]. A similar composition (l 2 :g 2 :g 1 -instead of l 2 :g 1 :g 1 -) is observed for the sodium analogue, upon recrystallisation from hexane, which permits loss of one equivalent of DME.…”

N,N′-Bis-Silylated Lithium Aryl Amidinates: Synthesis, Characterization, and the Gradual Transition of Coordination Mode from σ Toward π Originated by Crystal Packing Interactions

“…The Monomeric Supramolecular Structure. This packing arrangement, manifested in complexes 1 , 2 , 4 , and 12 from this work and four other published complexes, ,, corresponds to a monomeric structure in which no significant intermolecular forces that involve the amidinate core are present, as reflected by the intermolecular distance of about 4.7 Å for the above complexes. These complexes (Figures and ) also have very similar bond distances and angles (Table ).…”

Chemoselectivity Diversity in the Reaction of LiNC6F5SiMe3with Nitriles and the Synthesis, Structure, and Reactivity of Zirconium Mono- and Tris[2-(2-pyridyl)tetrafluorobenzimidazolate] Complexes

“…Unlike the four signals in the room-temperature 19 F NMR spectrum of 3 in toluene-d 8 , which support the retention of its solid-state structure in solution at these conditions, there are only two fluorine signals in the 19 F NMR spectrum of 3 in THF-d 8 . 11 This higher symmetry about the tetrafluorinated ring (AB pattern) implies that a rapid rotation of the pyridine ring and Li-N(imidazolate) bond breaking and formation are operative.…”

“…We have recently reported the formation of coordination polymers of 3-and 4-pyridylamidinates, which resulted from the coordination of lithium centers to the pendant nitrogen atoms at the expense of TMEDA. 18 The displacement of TMEDA with THF in complex 3 is also supported by the almost identical 1 H and 19 F NMR spectra (pyridyl and tetrafluorophenylene regions, respectively) of 3 and 5 in THF-d 8 .…”

Lithium and sodium N,N′-di(2,6-dialkylphenyl)formamidinate complexes

“…This appears reasonable given their identical composition (by 1 H NMR). Thus, the addition of alkyl steric bulk to the 2-and 6-aryl positions of DME solvated lithium N,N 0 -di(aryl)formamidinates brings about a decrease in diazaallyl NCN angle (4(4-Me); 127.7(2)° [ 11], 5; 125.4(2)°, 6; 120.4(1)°), which is consistent with a transition from bridging to chelating amidinate donor. This permits a decrease in aryl:NCN plane and aryl:aryl plane torsion angles from FMes to FPhEt (4(4-Me); mean 66.6°and 87.2(1)°resp.…”

“…For sodium metallation, failure to isolate crystalline samples of 7 (empirical composition by 1 H NMR [Na(FXyl)(THF) 2 ]) leave its structural composition open to conjecture, however, the DME analogue (10) exists as a monomer in the solid state whilst the lack of asymmetry in 1 H NMR spectra of 7, as per 8, debases the possibility of aryl-C contacts. The lithiation of HFPhEt in DME renders a l 2 :g 1 :g 1 -bound dimer similar to less bulky N,N 0 -di(aryl)formamidinates [8,11]. A similar composition (l 2 :g 2 :g 1 -instead of l 2 :g 1 :g 1 -) is observed for the sodium analogue, upon recrystallisation from hexane, which permits loss of one equivalent of DME.…”

N,N′-Bis-Silylated Lithium Aryl Amidinates: Synthesis, Characterization, and the Gradual Transition of Coordination Mode from σ Toward π Originated by Crystal Packing Interactions

“…The Monomeric Supramolecular Structure. This packing arrangement, manifested in complexes 1 , 2 , 4 , and 12 from this work and four other published complexes, ,, corresponds to a monomeric structure in which no significant intermolecular forces that involve the amidinate core are present, as reflected by the intermolecular distance of about 4.7 Å for the above complexes. These complexes (Figures and ) also have very similar bond distances and angles (Table ).…”

Chemoselectivity Diversity in the Reaction of LiNC6F5SiMe3with Nitriles and the Synthesis, Structure, and Reactivity of Zirconium Mono- and Tris[2-(2-pyridyl)tetrafluorobenzimidazolate] Complexes

“…Unlike the four signals in the room-temperature 19 F NMR spectrum of 3 in toluene-d 8 , which support the retention of its solid-state structure in solution at these conditions, there are only two fluorine signals in the 19 F NMR spectrum of 3 in THF-d 8 . 11 This higher symmetry about the tetrafluorinated ring (AB pattern) implies that a rapid rotation of the pyridine ring and Li-N(imidazolate) bond breaking and formation are operative.…”

“…We have recently reported the formation of coordination polymers of 3-and 4-pyridylamidinates, which resulted from the coordination of lithium centers to the pendant nitrogen atoms at the expense of TMEDA. 18 The displacement of TMEDA with THF in complex 3 is also supported by the almost identical 1 H and 19 F NMR spectra (pyridyl and tetrafluorophenylene regions, respectively) of 3 and 5 in THF-d 8 .…”

Lithium and sodium N,N′-di(2,6-dialkylphenyl)formamidinate complexes

“…This appears reasonable given their identical composition (by 1 H NMR). Thus, the addition of alkyl steric bulk to the 2-and 6-aryl positions of DME solvated lithium N,N 0 -di(aryl)formamidinates brings about a decrease in diazaallyl NCN angle (4(4-Me); 127.7(2)° [ 11], 5; 125.4(2)°, 6; 120.4(1)°), which is consistent with a transition from bridging to chelating amidinate donor. This permits a decrease in aryl:NCN plane and aryl:aryl plane torsion angles from FMes to FPhEt (4(4-Me); mean 66.6°and 87.2(1)°resp.…”

“…For sodium metallation, failure to isolate crystalline samples of 7 (empirical composition by 1 H NMR [Na(FXyl)(THF) 2 ]) leave its structural composition open to conjecture, however, the DME analogue (10) exists as a monomer in the solid state whilst the lack of asymmetry in 1 H NMR spectra of 7, as per 8, debases the possibility of aryl-C contacts. The lithiation of HFPhEt in DME renders a l 2 :g 1 :g 1 -bound dimer similar to less bulky N,N 0 -di(aryl)formamidinates [8,11]. A similar composition (l 2 :g 2 :g 1 -instead of l 2 :g 1 :g 1 -) is observed for the sodium analogue, upon recrystallisation from hexane, which permits loss of one equivalent of DME.…”