Divalent Manganese, Iron, and Cobalt Bis(trimethylsilyl)amido Derivatives and Their Tetrahydrofuran Complexes

Andersen, Richard A.; Bryan, Aimee M.; Faust, Michelle; Power, Philip P.

doi:10.1002/9781119477822.ch1

Cited by 6 publications

(16 citation statements)

References 38 publications

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Section: Resultsmentioning

confidence: 99%

“…Because of the high air and moisture sensitivity and high silicon content of the complexes, elemental analyses were not attempted. TiCl 3 (NMe 3 ) 2 , VCl 3 (NMe 3 ) 2 , LiN(SiMe 3 ) 2 ·(OEt 2 ), 5 wt % Na/NaCl, [Mn{N(SiMe 3 ) 2 } 2 ] 2 , [Co{N(SiMe 3 ) 2 } 2 ] 2 , and BrN(SiMe 3 ) 2 were prepared via literature procedures.…”

Section: Methodsmentioning

confidence: 99%

“…The divalent complexes M{N(SiMe 3 ) 2 } 2 of the mid and late first-row transition metals (M = Mn, Fe, Co) are prepared in a simple manner by reaction of 2 equiv of the alkali metal amide with the appropriate metal dihalide in diethyl ether and subsequent low-pressure distillation of the crude product. 40 The highly unstable divalent nickel amide may be prepared analogously. 8 Although a few Lewis base-stabilized complexes of Cr{N(SiMe 3 ) 2 } 2 are known, 34−37 no M{N-(SiMe 3 ) 2 } 2 complexes have been reported for the earlier transition metals titanium or vanadium.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe₃)₂}_n (n = 2, 3) Complexes

Stennett

Power

2021

Inorg. Chem.

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The reaction of 2 equiv of LiN(SiMe3)2·Et2O with TiCl3(NMe3)2 or VCl3(NMe3)2 afforded the dimeric, halide bridged complexes [Ti(μ-Cl){N(SiMe3)2}2]2 (1) or [V(μ-Cl){N(SiMe3)2}2]2 (2) in moderate yields. The reduction of titanium complex 1 with 3 equiv of 5% (wt) Na/NaCl gave the mixed metal titanium/sodium hydride cluster Ti2(μ-H)2{N(SiMe3)2}3{N(SiMe3)(SiMe2CH)}(Na) (3), which was formed by activation of two C–H bonds at a single methyl group of one of the bis(trimethylsilyl)amide ligands. Attempts to form the analogous vanadium complex by reduction of 2 gave only intractable products. Treatment of Co{N(SiMe3)2}2 with 1 equiv of BrN(SiMe3)2 (which was previously shown to give the unique three-coordinate cobalt(III) trisamide Co{N(SiMe3)2}3) afforded the polymeric [(μ-Br)Co{μ-N(SiMe3)(SiMe2CH2CH2Me2Si)(Me3Si)μ-N}Co(μ-Br)]∞ (4) as a second product, which was shown by a structural analysis to possess a carbon–carbon bond formed between the two ligands. Attempts to isolate manganese and iron complexes analogous to 4 were unsuccessful. The role of bromine in these reactions was further studied by examining the reaction of 0.5 equiv of elemental bromine with [Mn{N(SiMe3)2}2]2 or [Co{N(SiMe3)2}2]2, which for manganese was shown to give the previously reported manganese trisamide Mn{N(SiMe3)2}3 but for cobalt gives the dimeric amide-bridged [Co(Br){μ-N(SiMe3)2}]2 (5).

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe₃)₂}_n (n = 2, 3) Complexes

Stennett

Power

2021

Inorg. Chem.

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“…Melting points of samples in flame-sealed capillaries were determined using a Meltemp II apparatus equipped with a partial immersion thermometer. Magnetic susceptibility data were collected by the Evans method using the indicated deuterated solvent and were corrected using the appropriate diamagnetic constants. , [Fe{N(SiMe 3 ) 2 } 2 ] 2 and HSAr (Ar = C 6 H 3 -2,6-(2,6- i Pr 2 -C 6 H 3 ) 2 ) were prepared according to literature procedures. , The substituted phenols were purchased from Sigma-Aldrich and purified by recrystallization from hexanes after overnight storage as a solution in the same solvent over 4 Å molecular sieves.…”

Section: Methodsmentioning

confidence: 99%

“…18,19 [Fe{N-(SiMe 3 ) 2 } 2 ] 2 and HSAr (Ar = C 6 H 3 -2,6-(2,6-i Pr 2 -C 6 H 3 ) 2 ) were prepared according to literature procedures. 20,21 The substituted phenols were purchased from Sigma-Aldrich and purified by recrystallization from hexanes after overnight storage as a solution in the same solvent over 4 Å molecular sieves.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Low-Coordinate Iron Chalcogenolates and Their Complexes with Diethyl Ether and Ammonia

2021

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Treatment of Fe{N(SiMe3)2}2 with 2 equiv of the appropriate phenol or thiol affords the dimers {Fe(OC6H2-2,6-Bu t 2-4-Me)2}2 (1) and {Fe(OC6H3-2,6-Bu t 2)2}2 (2) or the monomeric Fe{SC6H3-2,6-(C6H3-2,6-Pr i 2)2}2 (3) in moderate to excellent yields. Recrystallization of 1 and 2 from diethyl ether gives the corresponding three-coordinate ether complexes Fe(OC6H3-2,6-Bu t 2-4-Me)2(OEt2) (4) and Fe(OC6H3-2,6-Bu t 2)2(OEt2) (5). In contrast, no diethyl ether complex is formed by the dithiolate 3. The 1H NMR spectra of 4 and 5 show equilibria between the ether complexes and the base-free dimers. A comparison of these spectra with those of the dimeric 1 and 2 allows an unambiguous assignment of the paramagnetically shifted signals. Treatment of 1 with excess ammonia gives the tetrahedral diammine Fe(OC6H2-2,6-Bu t 2-4-Me)2(NH3)2 (6). Ammonia is strongly coordinated in 6, with no apparent loss of ammine ligand either in solution or upon heating under low pressure. In contrast, significantly weaker ammonia coordination is observed when dithiolate 3 is treated with excess ammonia, which gives the diammine Fe{SC6H3-2,6-(2,6-Pr i 2-C6H3)2}2(NH3)2 (7). Complex 7 readily loses ammonia either in solution or under reduced pressure to give the monoammine complex Fe{SC6H3-2,6-(2,6-Pr i 2-C6H3)2}2(NH3) (8). The weak binding of ammonia by iron thiolate 7 reflects the likely behavior of the proposed iron–sulfur active site in nitrogenases, where release of ammonia is required to close the catalytic cycle.

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Characterization of the “Absent” Vanadium Oxo V(═O){N(SiMe₃)₂}₃, Imido V(═NSiMe₃){N(SiMe₃)₂}₃, and Imido-Siloxy V(═NSiMe₃)(OSiMe₃){N(SiMe₃)₂}₂ Complexes Derived from V{N(SiMe₃)₂}₃ and Kinetic Study of the Spontaneous Conversion of the Oxo Complex into Its Imido-Siloxy Isomer

2020

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The synthesis and characterization of V(O){N(SiMe 3 ) 2 } 3 (1), V(NSiMe 3 ){N(SiMe 3 ) 2 } 3 (2), and V(NSiMe 3 )(OSiMe 3 ){N(SiMe 3 ) 2 } 2 (3) are described. Prior attempts to synthesize the vanadium(V) oxo complex 1 via salt metathesis of VOCl 3 with the lithium or sodium silylamide salt had yielded either the putative rearranged species V(NSiMe 3 )(OSiMe 3 ){N(SiMe 3 ) 2 } 2 (3) or the oxo-bridged, dimetallic {(μ-O) 2 V 2 [N(SiMe 3 ) 2 ] 4 }. We now show that complex 1 is available by treatment of the vanadium(III) tris(silylamide) V{N(SiMe 3 ) 2 } 3 with iodosylbenzene. The imido complex 2 was obtained by treatment of V{N(SiMe 3 ) 2 } 3 with trimethylsilyl azide. Sublimation of 1 formed complex 3, which was determined to be V(NSiMe 3 )(OSiMe 3 ){N(SiMe 3 ) 2 } 2 , on the basis of infrared, electronic, and 1 H and 51 V NMR spectroscopies. Crystallographic disorder precluded a complete structural characterization of 3, although a four-coordinate V atom, as well as severely disordered ligands, were apparent. Comparison of the vibrational spectra of 1 and 2 allowed an unambiguous assignment of the V−O (995 cm −1 ) and V−N imide (1060 cm −1 ) stretching bands. The vibrational spectrum of complex 3 displayed strong absorbances at 1090 and 945 cm −1 , indicative of its metal imide and metal siloxide moieties. The 1 H NMR spectrum of 1 in deuterated benzene showed overlapping signals for the ligand protons proximal and distal to the oxo moiety at 0.52 and 0.38 ppm. The 1 H NMR spectrum of 2 in deuterated methylene chloride displayed distinct signals for the imido (0.41 ppm) and amido (0.35 ppm) protons, whereas 1 H NMR spectroscopy of 3 showed three signals in an intensity ratio consistent with the formula V(NSiMe 3 )(OSiMe 3 ){N(SiMe 3 ) 2 } 2 . 51 V NMR spectra of 1−3 revealed singlet resonances at −119 ppm (1), −24 ppm (2), and −279 ppm (3). The electronic spectra of 1−3 displayed single absorbances in the charge transfer region, consistent with their d 0 electron configurations. Kinetic studies of the spontaneous conversion of complex 1 to 3 were used to determine the rate constants (ca. 0.0002 s −1 (63 °C), 0.0006 s −1 (73 °C), 0.002 s −1 (83 °C)) and activation energy (ca. 20 kcal/mol) of this first-order process.

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Divalent Manganese, Iron, and Cobalt Bis(trimethylsilyl)amido Derivatives and Their Tetrahydrofuran Complexes

Cited by 6 publications

References 38 publications

Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe₃)₂}_n (n = 2, 3) Complexes

Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe₃)₂}_n (n = 2, 3) Complexes

Low-Coordinate Iron Chalcogenolates and Their Complexes with Diethyl Ether and Ammonia

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Divalent Manganese, Iron, and Cobalt Bis(trimethylsilyl)amido Derivatives and Their Tetrahydrofuran Complexes

Cited by 6 publications

References 38 publications

Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe3)2}n (n = 2, 3) Complexes

Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe3)2}n (n = 2, 3) Complexes

Low-Coordinate Iron Chalcogenolates and Their Complexes with Diethyl Ether and Ammonia

Characterization of the “Absent” Vanadium Oxo V(═O){N(SiMe3)2}3, Imido V(═NSiMe3){N(SiMe3)2}3, and Imido-Siloxy V(═NSiMe3)(OSiMe3){N(SiMe3)2}2 Complexes Derived from V{N(SiMe3)2}3 and Kinetic Study of the Spontaneous Conversion of the Oxo Complex into Its Imido-Siloxy Isomer

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Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe₃)₂}_n (n = 2, 3) Complexes

Hydrides, Halides, and Polymers: Some Unexpected Intermediates on the Routes to First-Row Transition Metal M{N(SiMe₃)₂}_n (n = 2, 3) Complexes