Search results for "Ferro"
showing 10 items of 2451 documents
Ferrocene compounds: methyl 1′-aminoferrocene-1-carboxylate
2010
The title compund, [Fe(C(5)H(6)N)(C(7)H(7)O(2))], features one strong intermolecular hydrogen bond of the type N-H...O=C [N...O = 3.028 (2) A] between the amine group and the carbonyl group of a neighbouring molecule, and vice versa, to form a centrosymmetric dimer. Furthermore, the carbonyl group acts as a double H-atom acceptor in the formation of a second, weaker, hydrogen bond of the type C-H...O=C [C...O = 3.283 (2) A] with the methyl group of the ester group of a second neighbouring molecule at (x, -y - 1/2, z - 1/2). The methyl group also acts as a weak hydrogen-bond donor, symmetry-related to the latter described C-H...O=C interaction, to a third molecule at (x, -y - 1/2, z + 1/2) t…
Stereochemical Consequences of Oxygen Atom Transfer and Electron Transfer in Imido/Oxido Molybdenum(IV, V, VI) Complexes with Two Unsymmetric Bidenta…
2012
Two equivalents of the unsymmetrical Schiff base ligand (L(tBu))(-) (4-tert-butyl phenyl(pyrrolato-2-ylmethylene)amine) and MoCl(2)(NtBu)O(dme) (dme = 1,2-dimethoxyethane) gave a single stereoisomer of a mixed imido/oxido Mo(VI) complex 2(tBu). The stereochemistry of 2(tBu) was elucidated using X-ray diffraction, NMR spectroscopy, and DFT calculations. The complex is active in an oxygen atom transfer (OAT) reaction to trimethyl phosphane. The putative intermediate five-coordinate Mo(IV) imido complex coordinates a PMe(3) ligand, giving the six-coordinate imido phosphane Mo(IV) complex 5(tBu). The stereochemistry of 5(tBu) is different from that of 2(tBu) as shown by NMR spectroscopy, DFT ca…
Oligonuclear Ferrocene Amides: Mixed‐Valent Peptides and Potential Redox‐Switchable Foldamers
2010
Trinuclear ferrocene tris-amides were synthesized from an Fmoc- or Boc-protected ferrocene amino acid, and hydrogen-bonded zigzag conformations were determined by NMR spectroscopy, molecular modelling, and X-ray diffraction. In these ordered secondary structures orientation of the individual amide dipole moments approximately in the same direction results in a macrodipole moment similar to that of α-helices composed of α-amino acids. Unlike ordinary α-amino acids, the building blocks in these ferrocene amides with defined secondary structure can be sequentially oxidized to mono-, di-, and trications. Singly and doubly charged mixed-valent cations were probed experimentally by Vis/NIR, param…
Congested ferrocenyl polyphosphanes bearing electron-donating or electron-withdrawing phosphanyl groups: assessment of metallocene conformation from …
2011
International audience; The synthesis of novel substituted cyclopentadienyl salts that incorporate both a congested branched alkyl group (tert-butyl, (triphenyl)methyl, or tri(4-tert-butyl)phenylmethyl) and a phosphanyl group is reported. The introduction of either electron-withdrawing or electron-donating substituents (furyl, i-propyl, cyclohexyl, tert-butyl) on P atoms was generally achieved in high yield. The modular synthesis of ferrocenyl polyphosphanes from an assembly of these cyclopentadienyl salts was investigated, leading to the formation of new triphosphanes (denoted as 9-12) and diphosphanes (denoted as 14-16). The resulting phosphanes are not sensitive to air or moisture, even …
Redox-responsive organometallic foldamers from ferrocene amino acid: Solid-phase synthesis, secondary structure and mixed-valence properties
2011
Oligoferrocenes Fmoc-Fca(n)-OMe (n=3-5) are assembled in a stepwise precise manner from Fmoc-protected ferrocene amino acid Fmoc-Fca-OH (H-Fca-OH = 1-amino-1'-ferrocene carboxylic acid; Fmoc = 9-fluorenylmethyloxycarbonyl) via amide bonds on solid supports by sequential Fmoc deprotection, acid activation and coupling steps. The resulting well-defined oligomers form ordered zigzag structures in THF solution with characteristic hydrogen bonding patterns. Electrochemical experiments reveal sequential oxidations of the individual ferrocene units in these peptides giving mixed-valent cations. Optical intervalence electron transfer is detected by intervalence transitions in the near-IR.
Formation and mixed-valent behaviour of a substituted tetraferrocenylstannane.
2010
A tetrasubstituted tetraferrocenylstannane is formed from 1-bromoferrocene-1′-carboxylic acid methyl ester and copper bronze. The molecular structure is almost perfectly tetrahedral with Fe⋯Fe distances of around 6 A. In solution two sequential one-electron processes and one two-electron process are indicative of mixed-valent intermediates. Intermetallic interactions have been probed by preparative oxidation, paramagnetic NMR spectroscopy, Mosbauer spectroscopy, UV/Vis/NIR spectroscopy and DFT calculations.
Synthesis, structure and magnetic properties of oligometallic systems derived from di- and trinuclear copper(ii) amido-oximate complexes
2008
Three heterometallic complexes [M(H(2)O)(n)][Cu(3)L(2)(H(2)O)] (M = Mn(2+), Co(2+) or Ba(2+)) and one dinuclear compound (CuDien)(CuL{H(2)O}) were prepared by interaction of anionic compounds Cu(3)L(2)(2-) or CuL(2-) with the corresponding cations (H(4)L = 1,9-dicyano-1,9-bis(hydroximino)-3,7-diazanonane-2,8-dione; Dien = 1,5-diamino-3-azapentane). The complexes [M(H(2)O)(n)][Cu(3)L(2)(H(2)O)] have a polymeric structure, formed via oligomerization of Cu(3)L(2)(2-) units and additionally, in the case of the Ba-salt, by binding of Cu(3)L(2)(2-) units through Ba(2+). Antiferromagnetic interactions occur in all the complexes, while for [Co(H(2)O)(6)][Cu(3)L(2)(H(2)O)] there is evidence of some …
Stepwise sequential redox potential modulation possible on a single platform.
2011
Step by step: The cluster [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-) is an excellent platform for making a stepwise tunable redox potential system by dehydroiodination. With the addition of up to eight iodine substituents (purple; see picture), there is a fall in the E(1/2)(Co(III)/Co(II)) value from -1.80 V to -0.68 V (vs. Fc(+)/Fc; Fc = ferrocene). A practical application of this tunability has been observed in the growth of polypyrrole.
Semiconductive and Magnetic One-Dimensional Coordination Polymers of Cu(II) with Modified Nucleobases
2013
Four new copper(II) coordination complexes, obtained by reaction of CuX2 (X = acetate or chloride) with thymine-1-acetic acid and uracil-1-propionic acid as ligands, of formulas [Cu(TAcO)2(H2O)4]·4H2O (1), [Cu(TAcO)2(H2O)2]n (2), [Cu3(TAcO)4(H2O)2(OH)2]n·4H2O (3), and [Cu3(UPrO)2Cl2(OH)2(H2O)2]n (4) (TAcOH = thymine-1-acetic acid, UPrOH = uracil-1-propionic acid) are described. While 1 is a discrete complex, 2-4 are one-dimensional coordination polymers. Complexes 2-4 present dc conductivity values between 10(-6) and 10(-9) S/cm(-1). The magnetic behavior of complex 2 is typical for almost isolated Cu(II) metal centers. Moderate-weak antiferromagnetic interactions have been found in complex…
Expanding the 2, 2’-bipyrimidine bridged 1D homonuclear coordination polymers family: [MIIbpymCl2] (M=Fe, Co) magnetic and structural characterization
2013
One pot reaction of hydrated chloride salts of Fe(II) and Co(II) with stoichiometric amounts of 2, 2’-bipyrimidine (bpym) in a methanol/ acetonitrile mixture afforded the corresponding 1D homonuclear coordination polymers, [μ-(bpym)MCl2]n. Crystal structures of both complexes are isomorphous in the highly symmetric orthorhombic space group Fddd. The 1D coordination polymers are composed of almost orthogonal alternating bipyrimidine bridges linking the {MCl2} units. The magnetic behaviour of the Fe(II)compound can be well understood as a uniform S=2 chain with antiferromagnetic exchange interaction between metal ion sites. In the case of the Co(II) ion, also an antiferromagnetic interaction …