17O NMR study of oxo metalloporphyrin complexes: Correlation with electronic structure of M O moiety

Fujii, Hiroshi; Kurahashi, Takuya; Tosha, Takehiko; Yoshimura, Tetsuhiko; Kitagawa, Teizo

doi:10.1016/j.jinorgbio.2006.01.009

Cited by 21 publications

(27 citation statements)

References 92 publications

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“…The 17 O NMR spectrum of an acetonitrile solution of 1 treated with excess (ca. 40 eq) 17 OH 2 displays signals located at δ 1060 and 930 ppm (Figure S41), which fall within the range expected for terminal titanium(IV) oxo (1000-1100 ppm) 15,28,29 and hydroxo ligands (700-1000 ppm), 29 respectively, and are in line with our assignment of this species as the mixed O≡Ti/Ti(OH) 2 bistetrametaphosphate complex. When a sample was permitted to age for 12 h, these resonances were observed to decrease in intensity with new signals appearing at δ 758 and 566 ppm ( Figure S42).…”

Section: ∎ Introductionsupporting

confidence: 86%

“…The solution 17 O NMR spectrum displays one sharp signal located at δ 1086 ppm that is assigned as the -yl oxygen of 2, and consistent with 17 O NMR studies of related terminal titanyl complexes. 15,28 The formation of 1 and 2 from [OTi(acac) 2 ] 2 is noteworthy in illustrating that the tri-and tetrametaphosphates are capable of breaking up the titanium(IV) bis-µ-oxo core of [OTi(acac) 2 ] 2 to result in the formation of terminal Ti≡O units. Titanium(IV) oxo species are typically susceptible to hydrolysis in the presence of moist air as they have the propensity to dimerize and oligomerize forming unreactive species containing Ti-O-Ti linkages, 3,29 so the formation of a well-defined, air-stable terminal titanyl complex is unusual.…”

Section: ∎ Introductionmentioning

confidence: 99%

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Terminal Titanyl Complexes of Tri- and Tetrametaphosphate: Synthesis, Structures, and Reactivity with Hydrogen Peroxide

Stauber

Cummins

2017

Inorg. Chem.

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The synthesis and characterization of tri- and tetrametaphosphate titanium(IV) oxo and peroxo complexes is described. Addition of 0.5 equiv of [OTi(acac)] to dihydrogen tetrametaphosphate ([POH]) and monohydrogen trimetaphosphate ([POH]) provided a bis(μ,κ,κ) tetrametaphosphate titanyl dimer, [OTiPO] (1; 70% yield), and a trimetaphosphate titanyl acetylacetonate complex, [OTiPO(acac)] (2; 59% yield). Both 1 and 2 have been structurally characterized, crystallizing in the triclinic P1̅ and monoclinic P2 space groups, respectively. These complexes contain Ti≡O units with distances of 1.624(7) and 1.644(2) Å, respectively, and represent rare examples of structurally characterized terminal titanyls within an all-oxygen coordination environment. Complexes 1 and 2 react with hydrogen peroxide to produce the corresponding peroxotitanium(IV) metaphosphate complexes [OTiPO](3; 61% yield) and [OTiPO(acac)] (4; 65% yield), respectively. Both 3 and 4 have been characterized by single-crystal X-ray diffraction studies, and their solid-state structures are presented. Complex 3 functions as an oxygen atom transfer (OAT) reagent capable of oxidizing phosphorus(III) compounds (P(OMe), PPh) and SMe at ambient temperature to result in the corresponding organic oxide with regeneration of dimer 1.

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Section: ∎ Introductionsupporting

confidence: 86%

Section: ∎ Introductionmentioning

confidence: 99%

Terminal Titanyl Complexes of Tri- and Tetrametaphosphate: Synthesis, Structures, and Reactivity with Hydrogen Peroxide

Stauber

Cummins

2017

Inorg. Chem.

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“…4,14 As can be seen, ν sym is insensitive to the nature of the meso substituent. Similar observations have been made for structurally related dioxo Ru VI porphyrins, 15 while fivecoordinate O=Cr IV porphyrins or O=Mn V tetraamido complexes are more sensitive to ligand substituents. 14,15 The IR spectrum of Mn V TPFPP afforded strong confirmation of the Raman assignments (Figure 1b).…”

supporting

confidence: 78%

“…Similar observations have been made for structurally related dioxo Ru VI porphyrins, 15 while fivecoordinate O=Cr IV porphyrins or O=Mn V tetraamido complexes are more sensitive to ligand substituents. 14,15 The IR spectrum of Mn V TPFPP afforded strong confirmation of the Raman assignments (Figure 1b). The IR-active but Raman-inactive ν asym for 16 O=Mn= 16 O was found by bandfitting to be at 805 cm −1 .…”

supporting

confidence: 78%

Trans-dioxo Manganese(V) Porphyrins

et al. 2007

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Transition metal oxo-species have been the focus of extensive studies because of their relevance to the redox biochemistry of dioxygen as well as myriads of oxidative catalytic processes. High valent oxo-manganese complexes have been described for porphyrin, 1 salen, 2 corrole, 3 corrolazine, 4 and non-heme systems. 5 The O=Mn V moiety has been suggested in the photosynthetic water oxidation process, 6 and a bridged Mn V porphyrin dimer has recently been demonstrated to oxidize water into dioxygen. 7 We have previously described low-spin d 2 oxomanganese(V) porphyrin complexes that display an extraordinary range of reactivity toward oxo-transfer as a function of prototropic equilibria involving the axial ligand. 8 A prediction of that work was that oxo-aqua and oxo-hydroxomanganese(V) intermediates are reactive oxidants while the stable species observed at high pH are trans-dioxo complexes. Here we provide the first definitive spectroscopic evidence for trans-dioxomanganese(V) porphyrins [O=Mn V =O]. Further, we show that protonation of these species affords the reactive intermediates usually associated with these catalytic systems (Scheme 1).

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“…Interestingly, the introduction of the Ti=O group in complexes 3a-c causes the appearance of peaks located near 700 and 900 cm -1 (3a: 744 cm -1 , 906 cm -1 ; 3b: 704 cm -1 , 743 cm -1 , 993 cm -1 ; 3c: 762 cm -1 , 938 cm -1 ). [10,[22][23] Because of the presence of the NH stretching, broad absorptions above 3000 cm -1 are observed for ligands 2b-c (2b: 3292 cm -1 , 2c: 3053 cm -1 ), while for compound 2a this broad peak is shifted to 2958 cm -1 . Complex 3c also shows a broad absorption around 3056 cm -1 , which can be attributed to the stretching of aromatic CH (see Supporting Information for full IR spectra).…”

Section: Ir Spectramentioning

confidence: 99%

Titanium‐Based Tetrakis‐2,3‐[5,6‐di(Substituted)pyrazino]porphyrazine: Synthesis and Characterization

et al. 2020

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Tetrapyrazinoporphyrazine (TPysPz) ligands and metal complexes find, generally, application as electronic materials and catalysts. Considering the limited application of Titanium (Ti), we prepared and characterized a family of ligands and Ti-based complexes of tetrakis-2,3-[5,6-di-R 8-pyrazino]porphyrazine (R = H, 2-Py, Ph). UV/Vis measurements in different solvents confirm molecular aggregation, which results more pronounced in the presence of 2-pyridil and phenyl substituents on the macrocycle edge. Because of low solubility, solid state NMR was applied for structure characterization.

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17O NMR study of oxo metalloporphyrin complexes: Correlation with electronic structure of M O moiety

Cited by 21 publications

References 92 publications

Terminal Titanyl Complexes of Tri- and Tetrametaphosphate: Synthesis, Structures, and Reactivity with Hydrogen Peroxide

Terminal Titanyl Complexes of Tri- and Tetrametaphosphate: Synthesis, Structures, and Reactivity with Hydrogen Peroxide

Trans-dioxo Manganese(V) Porphyrins

Titanium‐Based Tetrakis‐2,3‐[5,6‐di(Substituted)pyrazino]porphyrazine: Synthesis and Characterization

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