A series of iron(II) bis(triflate) complexes containing tripodal tetradentate nitrogen ligands with pyridine and dimethylamine donors the type [N(CH(2)Pyr)(3-n)()(CH(2)CH(2)NMe(2))(n)] [n = 0 (tpa, 1), n 1 (iso-bpmen, 3), 2 (Me(4)-benpa, 4), 3 (Me(6)-tren, 5)] linear ligand [(CH(2)Pyr)MeN(CH(2)CH(2))NMe(CH(2)Pyr), (bpmen, 2)] has been prepared. The preferred coordination geometry these in solid state CH(2)Cl(2) solution changes from six- to five-coordinate order 5. In acetonitrile, triflate...

High versus low: The high-yield generation of a synthetic high-spin oxoiron(IV) complex, [Fe(IV)(O)(TMG(3)tren)](2+) (see picture, TMG(3)tren = 1,1,1-tris{2-[N2-(1,1,3,3-tetramethylguanidino)]ethyl}amine), has been achieved by using the very bulky tetradentate ligand, in order to both sterically protect moiety and enforce trigonal bipyramidal geometry at iron center, for which an S 2 ground state is favored.

[FeIV(O)(TMG3tren)]2+ (1; TMG3tren = 1,1,1-tris{2-[N2-(1,1,3,3-tetramethylguanidino)]ethyl}amine) is a unique example of an isolable synthetic S 2 oxoiron(IV) complex, which serves as model for the high-valent intermediates observed in nonheme iron enzymes. Congruent with DFT calculations predicting more reactive center, 1 has lifetime significantly shorter than those related complexes. The self-decay exhibits strictly first-order kinetic behavior and unaffected by solvent deuteration,...

With a little help from some friends: the aid of HClO4 as proton and BPh4− electron source, Fe complex pentadentate pyridyl-appended cyclam ligand can activate dioxygen to yield corresponding oxoiron(IV) (see scheme; TMC-py=1-(2′-pyridylmethyl)-4,8,11-trimethyl-1,4,8,11-tetraazacyclotetradecane; C gray, magenta, N blue, O red). This transformation is proposed occur via hydroperoxoiron(III) intermediate. Supporting information for this article available on WWW under...

The trigonal-bipyramidal high-spin (S = 2) oxoiron(IV) complex [FeIV(O)(TMG2dien)(CH3CN)]2+ (7) was synthesized and spectroscopically characterized. Substitution of the CH3CN ligand by anions, demonstrated here for X N3– Cl–, yielded additional S 2 complexes general formulation [FeIV(O)(TMG2dien)(X)]+ (7-X). reduced steric bulk 7 relative to published [FeIV(O)(TMG3tren)]2+ (2) reflected enhanced rates intermolecular substrate oxidation.

A series of iron(II)-bis(triflate) complexes [Fe(L)(OTf)2] containing linear tetradentate bis(quinolyl)-diamine and bis(quinolylmethyl)-diamine ligands with a range ligand backbones has been prepared. The coordination geometries these have investigated in the solid state by X-ray crystallography solution 1H 19F NMR spectroscopy. Because labile nature high-spin iron(II) solution, dynamic equilibria different (cis-alpha, cis-beta, trans) are observed certain systems. In cases, geometry...

A series of non-heme iron(ii) bis(triflate) complexes containing linear and tripodal tetradentate ligands has been prepared. Electron withdrawing electron donating substituents in the para position pyridine as well effect pyrazine versus sulfur or oxygen donors instead nitrogen have investigated. The electronic effects induced by these influence strength ligand field. UV-vis spectroscopy magnetic susceptibility studies used to quantify VT (1)H (19)F NMR X-ray diffraction elucidate structural...

Abstract The five‐membered electron‐transfer series [M(bpy) 3 ] n and [M(tpy) 2 (M = Fe, Ru; bpy 2,2′‐bipyridine, tpy 2,2′:6′,2″‐terpyridine) [Fe( t bpy) ( 4,4′‐di‐ tert ‐butyl‐2,2′‐bipyridine; 3+, 2+, 1+, 0, 1–) have been investigated the electronic structure of so called “low‐valent” complexes established by a combination electro‐ magnetochemistry, electron paramagnetic resonance (EPR) Mössbauer spectroscopy, X‐ray crystallography, DFT calculations. These are accessed reduction d 6 S 0...

S = 2 Fe IV ═O species are key intermediates in the catalysis of most nonheme iron enzymes. This article presents detailed spectroscopic and high-level computational studies on a structurally-defined that define its frontier molecular orbitals, which allow high reactivity. Importantly, there both π- σ-channels for reaction, highly reactive because they develop dominant oxyl character at transition state. These have different orientation dependences defining how same substrate can undergo...

[Fe(Me2EBC)(OTf)2], the iron(II) complex of tetraazamacrocyclic Me2EBC ligand (Me2EBC = 4,11-dimethyl-1,4,8,11-tetraazabicyclo [6.6.2]hexadecane), has been investigated as a catalyst for olefin oxidation by H2O2 and compared to closely related [Fe(TMC)(OTf)](OTf) (TMC 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). Both complexes have ligands based on cyclam that differ in how they coordinate iron center. This difference results different orientations their remaining coordination...

We utilized two organic dications containing, respectively, a pyridinium and an imidazolium core to construct new n = 1 (where refers the number of contiguous two-dimensional (2D) inorganic layers, i.e., not separated by cations) 2D lead–iodide perovskites 2. The former material exhibits (100)- latter very rare 3 × (110)-structural type. Compared with primary ammonium functionality, their constituent ring-centered positive charges have lower charge density. As result, [PbI6]4–...

Published studies of layered (2D) (100)-oriented hybrid lead-bromide perovskites evidence a correlation between increased inter-octahedral (Pb-Br-Pb) distortions and the appearance broadband white light emission. However, impact within their constituent [PbBr6 ]4- octahedra has yet to be assessed. Herein, we report two new 2D Pb-Br perovskites, whose structures display unusually high intra-octahedral distortions, whilst retaining minimal distortions. Using combination temperature-dependent,...

A series of Fe(II), Mn(II), Co(II) and Ru(II) complexes containing bis(imino)pyridine or bis(amino)pyridine ligands weakly coordinating triflate (OTf-) non-coordinating SbF6- anions have been prepared. The fully characterized including several solid-state structure analyses. Two unusual mono-chelate six-coordinate Fe(II) Mn(II) observed. catalytic properties the for oxidation cyclohexane with H2O2 evaluated. Only shown activity, which is mainly due to Fenton-type free radical auto-oxidation.

Abstract A series of iron(II) bis(triflate) complexes [Fe(L)(OTf) 2 ] containing linear tetradentate bis(pyridylmethyl)diamine ligands with a range ligand backbones has been prepared. The backbone the varied from two‐carbon linkage [ethylene ( 1 ), 4,5‐dichlorophenylene ) and cyclohexyl 3 )] to three‐carbon [propyl 4 )) four‐carbon (butyl 5 )]. coordination geometries these have investigated in solid state by X‐ray crystallography solution H 19 F NMR spectroscopy. Due labile nature high‐spin...

Near-quantitative formation of an oxoiron(IV) intermediate [FeIV(O)(TMC)(CH3CN)]2+ (2) from stoichiometric H2O2 was achieved with [FeII(TMC)]2+ (1) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecane). This important outcome is best rationalized by invoking a direct reaction between 1 and followed heterolytic O−O bond cleavage facilitated acid−base catalyst (2,6-lutidine in our case). A sizable H/D KIE 3.7 observed for the 2, emphasizing importance proton transfer step. Pyridines...

Dissecting the barrier: The nuclear resonance vibrational spectrum of S=2 [(TMG3tren)FeIVO] complex revealed features indicative an axial "steric wall" that contributes to overall reaction barrier. DFT calculations show both (axial attack) and S=1 (equatorial surfaces possess steric contributions their barriers, estimates these effects result in comparable intrinsic barriers for spin (see picture). Detailed facts importance specialist readers are published as "Supporting Information". Such...

The electronic structures of the complexes [M((t)bpy)(3)](0,1-) (M = Nb, Ta; (t)bpy 4,4'-di-tert-butyl-2,2'-bipyridine) have been investigated using a combination UV-vis spectroscopy, EPR and XAS. Furthermore, crystal structure [Na(THF)(5)][Ta((t)bpy)(3)] has determined. These studies were supplemented by density functional theory (DFT) calculations extended to include series [Y(bpy)(3)](m) (m 0, 1-, 2-, 3-), [Ti(bpy)(3)](n) (n 1+, [Zr(bpy)(3)](p), [Hf(bpy)(3)](p) (p 2-). This allowed us...

We report the first conjugate acid–base pair of nonheme oxoiron(<sc>iv</sc>) complexes, which are supported by a tetramethylcyclam ligand with pendant amide that binds <italic>trans</italic> to oxo group <italic>via</italic> carbonyl oxygen.

Abstract The sluggish oxidants [Fe IV (O)(TMC)(CH 3 CN)] 2+ (TMC=1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclotetradecane) and (O)(TMCN‐d 12 )(OTf)] + (TMCN‐d =1,4,7,11‐tetra(methyl‐d )‐1,4,7,11‐tetraazacyclotetradecane) are transformed into the highly reactive oxidant (O)(TMCO)(OTf)] ( 1 ; TMCO=4,8,12‐trimethyl‐1‐oxa‐4,8,12‐triazacyclotetradecane) upon replacement of an NMe donor in TMC TMCN ligands by O atom. A rate enhancement five to six orders magnitude both H atom transfer reactions was...

The crystal structures of nine homoleptic, pseudooctahedral cobalt complexes, 1-9, containing either 2,2':6',2″-terpyridine (tpy), 4,4'-di-tert-butyl-2,2'-bipyridine ((t)bpy), or 1,10-phenanthroline (phen) ligands have been determined in three oxidation levels, namely, cobalt(III), cobalt(II), and, for the first time, corresponding presumed cobalt(I) species. intraligand bond distances complexes [Co(I)(tpy(0))2](+), [Co(I)((t)bpy(0))3](+), and [Co(I)(phen(0))3](+) are identical, within...

Ruthenium(II) and osmium(II) complexes [M(C^N^C)(N^N)L](n+) (L = Cl(-), n 1; L CH3CN, t-BuNC, 2) containing a neutral tridentate N-heterocyclic carbene (NHC)-based pincer ligand, either 2,6-bis(1-butylimidazol-2-ylidene)pyridine (C(1)^N^C(1)) or 2,6-bis(3-butylbenzimidazol-2-ylidene)pyridine (C(2)^N^C(2)), 2,2'-bipyridine-type aromatic diimine have been prepared. Investigations into the effects of varying M (Ru Os), C^N^C, N^N, on structural, electrochemical, absorption, emission...

The electronic structures of a series so-called "low-valent" transition metal complexes [M((Me)bpy)3](0) and [M(tpy)2](0) ((Me)bpy = 4,4'-dimethyl-2,2'-bipyridine tpy 2,2',6',2″-terpyridine) have been determined using combination X-ray crystallography, magnetochemistry, UV-vis-NIR spectroscopy. More specifically, the crystal long-known [Ti(IV)(tpy(2-))2](0) (S 0, 6), [V(IV)(tpy(2-))2] 1/2, 7), [Ti(III)((Me)bpy(•))3](0) 1), [V(II)((Me)bpy(•))2((Me)bpy(0))](0) 2), [Mo(III)((Me)bpy(•))3](0) 4)...

A corrugated (110)-oriented 2D Pb–Br perovskite was obtained by systematic modulation of templating dication structure. Upon excitation UV light, this material exhibits intrinsic “cold” white light emission.

A series of manganese(II), iron(II) and cobalt(II) bis(triflate) complexes containing linear tetradentate bis(imine) bis(amine) ligands with a biphenyl bridge have been synthesized. The twist in the ligand backbone due to unit leads case (1 2) sp2 hybridised N donors, distorted cis-alpha coordination geometry, whereas biphenyl- biphenylether-bridged (7 - 9 12), trans geometry is observed. catalytic properties for oxidation cyclohexane, using H2O2 as oxidant, evaluated. Only iron show any...

Abstract Hoch vs. niedrig : Die Synthese eines High‐Spin‐Oxoeisen(IV)‐Komplexes, [Fe IV (O)(TMG 3 tren)] 2+ (siehe Bild, TMG tren=1,1,1‐Tris{2‐[ N 2‐(1,1,3,3‐tetramethylguanidino)]ethyl}amin), gelang in hohen Ausbeuten mithilfe des sperrigen vierzähnigen tren‐Liganden, der zum einen die Oxoeisen(IV)‐Einheit sterisch abschirmt und anderen eine trigonal‐bipyramidale Geometrie am Eisenzentrum erzwingt, für ein S =2‐Grundzustand bevorzugt ist. magnified image