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This paper compares the local geometries, spin states, and redox properties of a series of iron complexes supported by neutral, tetradentate N[P.sub.3] (tris(phosphine)amine) and N[S.sub.3] (tris(thioether)amine) ligands. Our consideration of an Fe-mediated [N.sub.2] fixation scheme similar to that proposed by Chatt for molybdenum motivates our interest in systems of these types. This report specifically describes the synthesis and characterization of cationic Fe(II) chloride complexes supported by the neutral ligands N[P.sup.i-Pr.sub.3] (N[P.sup.i-Pr.sub.3] = [N[(C[H.sub.2]C[H.sub.2]P-i-[Pr.sub.2]).sub.3]]), NAr[P.sup.i-Pr.sub.3] (NAr[P.sup.i-Pr.sub.3] = [N[(2diisopropylphosphine-4- methylphenyl).sub.3]]), and [NS.sup.t-Bu.sub.3] ([NS.sup.t-Bu.sub.3] = [N[(C[H.sub.2]C[H.sub.2]S-t-Bu)3].sub.3]). The solid-state structures, electrochemistry, and magnetic properties of these complexes are reported. Whereas the N[P.sup.i-Pr.sub.3] and NAr[P.sup.i-Pr.sub.3] ligands provide pseudotetrahedral S = 2 ferrous cations [Fe(N[P.sup.i-Pr.sub.3])CI]P[F.sub.6] (1[P[F.sub.6]]) and [Fe(NAr[P.sup.i-Pr.sub.3])C1]B[Ph.sub.4] (2[B[Ph.sub.4]]) featuring a long Fe--N bond distance, the [NS.sup.t-Bu.sub.3] ligand gives rise to a trigonal bipyramidal structure with a S = 1 ground state and a much shorter Fe--N interaction. The complexes 1[B[Ph.sub.4]] and 2[B[Ph.sub.4]] can be reduced under CO to give rise to the five-coordinate Fe(I) monocarbonyls [Fe(N[P.sup.i-Pr.sub.3])CO]B[Ph.sub.4] (4[B[Ph.sub.4]]) and [Fe(NAr[P.sup.i-Pr.sub.3])CO]B[Ph.sub.4] (5[B[Ph.sub.4]]). The solidstate structures and electrochemistry of 4[B[Ph.sub.4]] and 5[B[Ph.sub.4]] are described, as is the EPR spectrum of 4[B[Ph.sub.4]]. The synthesis and characterization of the hydride--dinitrogen complex [Fe(N[P.sup.i-Pr.sub.3])([N.sub.2])(H)]P[F.sub.6] (6[P[F.sub.6]]) has also been accomplished and its properties are also reported. Key words: nitrogenase, iron, polydentate phosphines, thioether ligands, [N.sub.2] chemistry, nitrogen, Fe(I). Resume : Dans ce travail, on compare les geometries locales, etats de spin et proprietes redox d'une serie de complexes de fer supportes par les ligands neutres et tridentates N[P.sub.3] (tris(phosphine)amine) et N[S.sub.3] (tris(thioether)amine). Notre consideration d'un schema de fixation du [N.sub.2] catalyse par le Fe semblable a celui propose par Chart pour le molybdene motive notre interet darts les systemes de ce type. Dans ce travail, on decrit specifiquement la synthese et la caracterisation de complexes cationiques du chlorure de Fe(II) supportes par les ligands neutres N[P.sup.i-Pr.sub.3] (N[P.sup.i-Pr.sub.3] = [N[(C[H.sub.2]C[H.sub.2]P-i-[Pr.sub.2]).sub.3]]), NAr[P.sup.i-Pr.sub.3] (NAr[P.sup.i-Pr.sub.3] = [N[(2-diisopropylphosphine-4-methylphenyl).sub.3]]) et [NS.sup.t-Bu.sub.3] ([NS.sup.t-Bu.sub.3] = [N[(C[H.sub.2]C[H.sub.2]S-t-Bu).sub.3]]), y compris les structures a l'etat solide, l'e1ectrochimie et les proprietes magnetiques de ces complexes. Alors que les ligands N[P.sup.i-Pr.sub.3] et NAr[P.sup.i-Pr.sub.3] conduisent a des cations ferreux pseudotetraedriques S = 2 [Fe(N[P.sup.i-Pr.sub.3])Cl]P[F.sub.6] (1[P[F.sub.6]]) et [Fe(NAr[P.sup.i-Pr.sub.3])CI]B[Ph.sub.4] (2[B[Ph.sub.4]]) comportant une longue liaison Fe--N, le ligand [NS.sup.t-Bu.sub.3] conduit a la formation d'un complexe de structure bipyramidale trigonale avec un etat fondamental S = 1 et une interaction Fe--N beaucoup plus courte. Les complexes l[B[Ph.sub.4]] et 2[B[Ph.sub.4]] peuvent etre reduits sous l'influence du CO pour conduire a des complexes monocarbonyles et pentacoordines du Fe(I), [Fe(N[P.sup.i-Pr.sub.3])CO]B[Ph.sub.4] (4[B[Ph.sub.4]]) et [Fe(NAr[P.sup.i-Pr.sub.3])CO]B[Ph.sub.4] 5[B[Ph.sub.4]]. On decrit aussi les structures solides et l'electrochimie des complexes 4[B[Ph.sub.4]] et 5[B[Ph.sub.4]] ainsi que le spectre RPE du compose 4[B[Ph.sub.4]]. On a aussi realise la synthese et la caracterisation du complexe hydrure--diazote [Fe(N[P.sup.iPr.sub.3])([N.sub.2])(H)] P[F.sub.6] (6[P[F.sub.6]]) et on rapporte ses proprietes. Mots cles : nitrogenase, fer, phosphines polydentates, ligands thioether, chimie du [N.sub.2], azote, Fe(I). [Traduit par la Redaction]

Research has been conducted on the tripodal ligand used in the synthesis of different monomeric complexes with the terminal hydroxo ligands. The isolation and characterization of these complexes have been carried out and the results are reported.

The development of a new polymer material that reversibly binds nitric oxide is reported.

The syntheses of two tripodal phenylamine-based ligands that can coordinate to [Co.sup.II] complexes to form monomeric complexes are explained. The analysis reveals that the cyanide coordination of these complexes can produce various electrochemically active species.

The synthesis and characterization of a host of nickel complexes supported by BP3 ligands is focused along with the theoretical and reactivity issues pertinent to the possible construction of L3Ni=E and L3Ni triple bond E linkages. The stabilization of the lower oxidation states of nickel by tris(phosphino)borate scaffolds is demonstrated while maintaining a four-coordinate tetrahedral geometry.

The formation and properties of a new series of mononuclear Fe(III) and Mn(III) complexes with terminal oxo and hydroxo ligands that are derived directly from dioxygen is presented. Theoretically derived molecular orbital energy level diagrams and corresponding plot for orbitals pertaining to the M(III)-O bonds in [Fe(III)H31(O)2- and [Mn(III)H31(O)]2 is illustrated.

The synthesis and properties of monomeric Mn(super III/II)-OH and Mn(super III)-O complexes derived from water are reported. The Mn(super III/II)O-H bond dissociation energies [BDE(sub OH)] which are important to understand the function of Mn-O(H) units in metalloproteins are estimated.

The activation of [O.sub.2] by Fe(II) complexes is of fundamental importance in biology. Heme and nonheme iron enzymes use [O.sub.2] as the primary oxidant in various biochemical transformations (1-3). In [...], Iron species with terminal oxo ligands are implicated as key intermediates in several synthetic and biochemical catalytic cycles. However, there is a dearth of structural information regarding these types of complexes because their instability has precluded isolation under ambient conditions. The isolation and structural characterization of an iron(III) complex with a terminal oxo ligand, derived directly from dioxygen ([O.sub.2]), is reported. A stable structure resulted from placing the oxoiron unit within a synthetic cavity lined with hydrogen-bonding groups. The cavity creates a microenvironment around the iron center that aids in regulating [O.sub.2] activation and stabilizing the oxoiron unit. These cavities share properties with the active sites of metalloproteins, where function is correlated strongly with site structure.

This paper compares the local geometries, spin states, and redox properties of a series of iron complexes supported by neutral, tetradentate NP3 (tris(phosphine)amine) and NS3 (tris(thioether)amine) ligands. Our consideration of an Fe-mediated N2 fixation scheme similar to that proposed by Chatt for molybdenum motivates our interest in systems of these types. This report specifically describes the synthesis and characterization of cationic Fe(II) chloride complexes supported by the neutral ligands NPi-Pr3 (NPi-Pr3 = [N(CH2CH2P-i-Pr2)3]), NArPi-Pr3 (NArPi-Pr3 = [N(2-diisopropylphosphine-4-methylphenyl)3]), and NSt-Bu3 (NSt-Bu3 = [N(CH2CH2S-t-Bu)3]). The solid-state structures, electrochemistry, and magnetic properties of these complexes are reported. Whereas the NPi-Pr3 and NArPi-Pr3 ligands provide pseudotetrahedral S = 2 ferrous cations [Fe(NPi-Pr3)Cl]PF6 (1[PF6]) and [Fe(NArPi-Pr3)Cl]BPh4 (2[BPh4]) featuring a long Fe—N bond distance, the NSt-Bu3 ligand gives rise to a trigonal bipyramidal structure with a S = 1 ground state and a much shorter Fe–N interaction. The complexes 1[BPh4] and 2[BPh4] can be reduced under CO to give rise to the five-coordinate Fe(I) monocarbonyls [Fe(NPi-Pr3)CO]BPh4 (4[BPh4]) and [Fe(NArPi-Pr3)CO]BPh4 (5[BPh4]). The solid-state structures and electrochemistry of 4[BPh4] and 5[BPh4] are described, as is the EPR spectrum of 4[BPh4]. The synthesis and characterization of the hydride–dinitrogen complex [Fe(NPi-Pr3)(N2)(H)]PF6 (6[PF6]) has also been accomplished and its properties are also reported.Key words: nitrogenase, iron, polydentate phosphines, thioether ligands, N2 chemistry, nitrogen, Fe(I). [ABSTRACT FROM AUTHOR]

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A series of divalent, monovalent, and zerovalent nickel complexes supported by the electron-releasing, monoanionic tris(phophino)borate ligands (PhBP3] and [PhBpiPr3] and [PhBP3] = [PhB(CH2PPh2)3]-, [PhBPiPr3] = [PhB(CH2PPr2)3) have been synthesized to explore fundamental aspects of their coordination chemistry. The pseudotetrahedral, divalent halide complexes (PhBP3]NiCl (1), [PhBP3Nil (2), and [PhBPiPr3]NiCl (3) were prepared by the metalation of [PhBP3]Tl or [PhBPiPr3)Tl with [Ph3P)2NiCl2, Nil2, and (DME)NiCl2 (DUE: 1,2-dimethoxyethane), respectively. Complex 1 is a versatile precursor to a series of complexes accessible via substitution reactions including [PhBP3]Ni(N3) (4), [PhBP3]Ni(OSiPh3) (5), [PhBP3]Ni(O-p-tBu-Ph) (6), and [PhBP3]Ni(S-p-tBu. Ph) (7). Complexes 2-5 and 7 have been characterized by X-ray diffraction (XRD) and are pseudotetrahedral monomers in the solid state. Complex 1 reacts readily with oxygen to form the four-electron-oxidation product, '[[PhB(CH2P(O)Ph2)2(CH2PPh2)]NiCl} (SA or 8B), which features a solid-state structure that is dependent on its method of crystallization. Chemical reduction of 1 using Na/Hg or other potential 1-electron reductants generates a product that arises from partial ligand degradation, [PhBP3]Ni(n²-CH2PPh2) (9). The more sterically hindered chloride 3 reacts with Li(dbabh) (Hdbabh = 2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta.2,5.diene) to provide the three-coordinate complex [κ²-PhBpiPr3]Ni(dbabh) (11), also characterized by XRD. Chemical reduction of complex 1 in the presence of L-type donors produces the tetrahedral Ni(I) complexes [PhBP3]Ni(PPh3) (12) and [PhBP3]Ni(CNtBu) (13). Reduction of 3 following the addition of PMe3 or tert-butyl isocyanide affords the Ni(I) complexes [PhBPiPr3]Ni(PMe3) (14) and [PhBPiPr3]Ni(CNtBu) (15), respectively. The reactivity of these [PhBP3]NiIL and [PhBPiPr3]NiIL complexes with respect to oxidative group transfer reactions from organic azides and diazoalkanes is discussed. The zerovalent nitrosyl complex [PhBP3]Ni(NO) (16) is prepared by the reaction of 1 with excess NO or by treating 12 with stoichiometric NO. The anionic Ni(O) complexes [[κ²-PhBP3]Ni(CO)2][nBu4N] (17) and [[,κ²-PhBPiPiPrNi(CO)2][ASN] (18) (ASN = 5 azoniaspiro [4.4]nonane) have been prepared by reacting [PhBP3]TI or [PhBPiPr3]TI with (Ph3P)2Ni(CO)2 in the presence of R4NBr. The photolysis of 17 appears to generate a new species consistent with a zerovalent monocarbonyl complex which we tentatively assign as {[PhBP3]Ni(CO)}{nBu4N}, although complete characterization of this complex has been difficult. Finally, theoretical DFT calculations are presented for the hypothetical Iow spin complexes [PhBP3]Ni(NtBu), [PhBPiPr3]Ni(NtBu), [PhBPiPr3]Ni(NMe), and [PhBPiPr3]Ni(N) to consider what role electronic structure factors might play with respect to the relative stability of these species. [ABSTRACT FROM AUTHOR]

Non-heme iron and manganese species with terminal oxo ligands are proposed to be key intermediates in a variety of biological and synthetic systems; however, the stabilization of these types of complexes has proven difficult because of the tendency to form oxo-bridged complexes. Described herein are the design, isolation, and properties for a series of mononuclear FeIII and MnIII complexes with terminal oxo or hydroxo ligands. Isolation of the complexes was facilitated by the tripodal ligand tris[(N-tert-butylureaylato)-N-ethyl]aminato ([H31]3-), which creates a protective hydrogen bond cavity around the MIII- O(H) units (MIII = Fe and Mn). The MIII-O(H) complexes are prepared by the activation of dioxygen and deprotonation of water. In addition, the MIII-O(H) complexes can be synthesized using oxygen atom transfer reagents such as N-oxides and hydroxylamines. The [FeIIIH31 (O)]2- complex also can be made using sulfoxides. These findings support the proposal of a high valent MIV-oxo species as an intermediate during dioxygen cleavage. Isotopic labeling studies show that oxo ligands in the [MIIIH31 (O)]2- complexes come directly from the cleavage of dioxygen: for [FIIIH31 (O)]2- the v(Fe-16O) = 671 cm-1, which shifts 26 cm-1 in [FeIIIH31(18O)]2- (v(Fe-18O) = 645 cm-1); a v(Mn-16O) = 700 cm-1 was observed for [MnIIIH31(16O)]2-, which shifts to 672 cm-1 in the Mn-18O isotopomer. X-ray diffraction studies show that the Fe-O distance is 1.813(3) Å in [FeIIIH31(O)]2-, while a longer bond is found in [FeIIIH31(OH)]- (Fe-O at 1.926(2) Å). [ABSTRACT FROM AUTHOR]

The syntheses of two phenylamine-based ligand systems, N(o- PhNH2)3 and N(o-PhNHC(O)tPr)3, are reported. These ligands readily coordinate to CoII to form monomeric complexes. X-ray diffraction studies establish that the [N(o-PhNC(O)iPr)3]3 ligand stabilizes the CoII ion in a trigonal-monopyramidal coordination environment. The axial coordination site in this complex is accessible and, upon cyanide coordination, generates an electro-chemically active species. [ABSTRACT FROM AUTHOR]

A dinuclear Co(ii) complex supported by a modular, tunable redox-active ligand system is capable of selective C-H amination to form indolines from aryl azides in good yields at low (1 mol%) catalyst loading. The reaction is tolerant of medicinally relevant heterocycles, such as pyridine and indole, and can be used to form 5-, 6-, and 7-membered rings. The synthetic versatility obtained using low loadings of an earth abundant transition metal complex represents a significant advance in catalytic C-H amination technology.

The name of one of the authors in the paper by Kluge et al. [Acta Cryst. (2011), E67, o2143] is corrected.[This corrects the article DOI: 10.1107/S1600536811028947.].

The title compound, C(8)H(17)NO, crystallizes with two independent mol-ecules in the asymmetric unit. In the crystal, inter-molecular N-H⋯O hydrogen bonding is observed between neighboring mol-ecules, forming continuous mol-ecular chains along the c-axis direction.