Rhodium(I) complexes containing bidentate pyrazolylgallate ligands. X-ray crystal structures of [Me2Gapz2]Rh(COD), [Rh(μ-3,5-Me2pz)(CO)2]2, and [Rh(μ-3,5-Me2pz)(COD)]2

1984 ◽  
Vol 62 (6) ◽  
pp. 1057-1067 ◽  
Author(s):  
Brenda M. Louie ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Structural Parameters ◽  
Heavy Atom ◽  
Boat Conformation ◽  
Nmr Studies ◽  
Space Group ◽  
H Nmr ◽  
Square Planar ◽  
Dirhodium Complexes

The synthesis and characterization of the complexes [Me2Gapz2]Rh(LL) (where LL = COD, (CO)2, (PPh3)2, or (PPh3)(CO)), incorporating the bidentate, chelating, dimethylbis(1-pyrazolyl)gallate ligand are described. Non-rigidity in solution has been demonstrated by 1H nmr studies for some of the complexes. A crystal structure determination of the COD complex has confirmed the boat conformation for the Ga—(N—N)2—Rh six-membered ring in this complex in the solid state. In addition, the solid state structures of the 3,5-dimethylpyrazolyl bridged dirhodium complexes [Rh(μ-3,5-Me2pz)(CO)2]2 and [Rh(μ-3,5-Me2pz)(COD)]2 have been determined. Crystals of [Me2Gapz2]Rh(COD) are orthorhombic, a = 22.7447(8), b = 11.9776(5), c = 6.4635(3) Å, Z = 4, space group Pnma; those of [Rh(μ-3,5-Me2pz)(CO)2]2 are monoclinic, a = 8.7403(6), b = 16.3594(6), c = 25.434(2) Å, β = 95.286(3)°, Z = 8, space group P21/c; and those of [Rh(μ-3,5-Me2pz)(COD)]2 are triclinic, a = 10.350(2), b = 11.401(2), c = 12.355(2) Å, α = 112.485(7), β = 99.394(9), γ = 105.387(8)°, Z = 2, space group [Formula: see text]. All three structures were solved by conventional heavy atom techniques and were refined by full-matrix least-squares procedures to final conventional R values of 0.026, 0.024, and 0.037 for 1824, 5135, and 6109 reflections with I ≥ 3σ(I), respectively. In each case the Rh atoms have distorted square planar coordination geometry. Important mean structural parameters are Rh—N = 2.087(2), Rh—C = 2.129(2), [Formula: see text] for [Me2Gapz2]Rh(COD); Rh—N = 2.063(6), Rh—CO = 1.852(9), [Formula: see text] for [Rh(μ-3,5-Me2pz)(CO)2]2; and Rh—N = 2.084(1), Rh—C = 2.131(7), [Formula: see text] for [Rh(μ-3,5-Me2pz)(COD)]2.

Synthesis and characterization of [Me2Ga(3,5-Me2pz)2]Rh(CO)PPh3 and the X-ray structure of its toluene solvate

1985 ◽  
Vol 63 (2) ◽  
pp. 503-508 ◽  
Author(s):  
Brenda M. Louie ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Physical Properties ◽  
Least Squares ◽  
Heavy Atom ◽  
Synthesis And Characterization ◽  
Boat Conformation ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Square Planar

Details of the synthesis and physical properties of [Me2Ga(3,5-Me2pz)2]Rh(CO)PPh3 are given. Crystals of [dimethylbis(3,5-dimethyl-1-pyrazolyl)gallato-N,N′](triphenylphosphine)carbonylrhodium(I) – toluene (1:1) are triclinic, a = 10.690(2), b = 12.928(2), c = 13.998(2) Å, α = 77.44(1), β = 83.50(1), γ = 72.70(1)°, Z = 2, space group [Formula: see text]. The structure was solved by conventional heavy-atom methods and was refined by full-matrix least-squares procedures to R = 0.039 and Rw = 0.048 for 5987 reflections with I ≥ 3σ(I). The Rh(I) is in a distorted square planar environment with Rh—N = 2.090(3) and 2.097(2), Rh—CO = 1.815(4), and Rh—P = 2.2700(8) Å. The central six-membered RhGaN4 ring has a steep boat conformation with a [Formula: see text] separation of 3.3819(4) Å.

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

Structure, magnetism and colour in simple bis(phosphine)nickel(II) dihalide complexes: an experimental and theoretical investigation

2013 ◽  
Vol 69 (12) ◽  
pp. 1437-1447 ◽  
Author(s):  
Madeleine Schultz ◽  
Philipp-Nikolaus Plessow ◽  
Frank Rominger ◽  
Laura Weigel
Keyword(s):  
Solid State ◽  
Theoretical Investigation ◽  
Density Functional ◽  
Solution Structure ◽  
Room Temperature ◽  
Energy Surface ◽  
H Nmr ◽  
Square Planar ◽  
Phosphine Complex ◽  
Bright Blue

The complex [1,2-bis(di-tert-butylphosphanyl)ethane-κ2P,P′]diiodidonickel(II), [NiI2(C18H40P2] or (dtbpe-κ2P)NiI2, [dtbpe is 1,2-bis(di-tert-butylphosphanyl)ethane], is bright blue–green in the solid state and in solution, but, contrary to the structure predicted for a blue or green nickel(II) bis(phosphine) complex, it is found to be close to square planar in the solid state. The solution structure is deduced to be similar, because the optical spectra measured in solution and in the solid state contain similar absorptions. In solution at room temperature, no31P{1H} NMR resonance is observed, but the very small solid-state magnetic moment at temperatures down to 4 K indicates that the weak paramagnetism of this nickel(II) complex can be ascribed to temperature independent paramagnetism, and that the complex has no unpaired electrons. The red [1,2-bis(di-tert-butylphosphanyl)ethane-κ2P,P′]dichloridonickel(II), [NiCl2(C18H40P2] or (dtbpe-κ2P)NiCl2, is very close to square planar and very weakly paramagnetic in the solid state and in solution, while the maroon [1,2-bis(di-tert-butylphosphanyl)ethane-κ2P,P′]dibromidonickel(II), [NiBr2(C18H40P2] or (dtbpe-κ2P)NiBr2, is isostructural with the diiodide in the solid state, and displays paramagnetism intermediate between that of the dichloride and the diiodide in the solid state and in solution. Density functional calculations demonstrate that distortion from an ideal square plane for these complexes occurs on a flat potential energy surface. The calculations reproduce the observed structures and colours, and explain the trends observed for these and similar complexes. Although theoretical investigation identified magnetic-dipole-allowed excitations that are characteristic for temperature-independent paramagnetism (TIP), theory predicts the molecules to be diamagnetic.

Über das [C7H7Fe2(CO)5]--Anion (C7H7 = Cycloheptatrienyl) / About the [C7H7Fe2(CO)5]--Anion (C7H7 = Cycloheptatrienyl)

1983 ◽  
Vol 38 (11) ◽  
pp. 1446-1453 ◽  
Author(s):  
Matthias Moll ◽  
Helmut Behrens ◽  
Werner Popp ◽  
Günther Liehr ◽  
Wolf Peter Fehlhammer
Keyword(s):  
Solid State ◽  
Iron Atom ◽  
Nmr Spectra ◽  
Structural Parameters ◽  
Anionic Complex ◽  
Polar Solvents ◽  
Space Group ◽  
X Ray

AbstractThe extremely unstable anionic complex [C7H7Fe2(CO)6]- (C7H7 = cycloheptatrienyl) which decomposes in polar solvents under CO elimination to give [C7H7Fe2(CO)5]- can be prepared by deprotonation of C7H8Fe2(CO)6 (C7H8 = cycloheptatriene) with NaN(SiMe3)2 in C6H6.The NMR spectra of [C7H7Fe2(CO)5]- show the highly fluctional character of this anion in solution. The X-ray structural parameters of Ph4As[C7H7Fe2(CO)5] (space group P21/n) can be interpreted in terms of a rotation of the tub shaped C7H7 ring against the CO bridged Fe2(CO)5 fragment in the solid state. Consequently, each iron atom is alternatingly η3 -or η4-coordinated to the allyl anion and the diene part, respectively, of the anionic 8π system of the cycloheptatrienyl ring.

scholarly journals Deuterium Solid State NMR Studies of Intact Bacteria Treated With Antimicrobial Peptides

2021 ◽  
Vol 2 ◽  
Author(s):  
Valerie Booth
Keyword(s):  
Solid State ◽  
Antimicrobial Peptides ◽  
Solid State Nmr ◽  
Model Membranes ◽  
Nmr Studies ◽  
Intact Cells ◽  
Whole Cells ◽  
H Nmr ◽  
Structure And Dynamics ◽  
Lipid Mixtures

Solid state NMR has been tremendously useful in characterizing the structure and dynamics of model membranes composed of simple lipid mixtures. Model lipid studies employing solid state NMR have included important work revealing how membrane bilayer structure and dynamics are affected by molecules such as antimicrobial peptides (AMPs). However, solid state NMR need not be applied only to model membranes, but can also be used with living, intact cells. NMR of whole cells holds promise for helping resolve some unsolved mysteries about how bacteria interact with AMPs. This mini-review will focus on recent studies using 2H NMR to study how treatment with AMPs affect membranes in intact bacteria.

Structure and magnetic properties of monophenylphosphinate bridged chain polymers of manganese(II), [MnL2(HPhPO2)2]x (where L = HPhPO2H, CH3CONH2, H2O, HCONH(CH3), and C5H5N)

1992 ◽  
Vol 70 (3) ◽  
pp. 732-741 ◽  
Author(s):  
Jing-Long Du ◽  
Steven J. Rettig ◽  
Robert C. Thompson ◽  
James Trotter ◽  
Peter Betz ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Heavy Atom ◽  
Indirect Evidence ◽  
Magnetic Coupling ◽  
Coupling Constants ◽  
Space Group ◽  
Linear Chains ◽  
Pyridine Complex ◽  
Square Planar ◽  
Neutral Ligands

Crystals of Mn(CH3CONH2)2(HPhPO2)2 are monoclinic, a = 5.668(2), b = 7.500(2), c = 23.104(2) Å, β = 95.52(2)°, Z = 2, space group P21/c, and those of Mn(HPhPO2H)2(HPhPO2)2 are monoclinic, a = 23.281(1), b = 5.508(2), c = 20.5489(6) Å, β = 90.424(4)°, Z = 4, space group C2/c. The structures were solved by heavy-atom methods and were refined by full-matrix least-squares procedures to R = 0.028 and 0.035 for 2081 and 2117 reflections with I ≥ 3σ(I), respectively. Both compounds have structures consisting of polymeric chains propagating along the crystallographic b axis; two phosphinate ligands bridge adjacent manganese atoms forming square planar MO4 units, and six coordination about the metal is achieved by axially O-bonded neutral ligands. Indirect evidence supports similar structures for the other complexes studied here. The complexes are antiferromagnetic and the magnetic susceptibilities have been analyzed according to two Heisenberg models for linear chains. The exchange coupling constants range from −0.30 cm−1 for the acetamide complex to −0.06 cm−1 for the pyridine complex. Magnetostructural correlations involving these complexes and the previously studied Mn(HCONH2)2(HPhPO2)2, reveal that the magnitude of the magnetic coupling is enhanced by symmetrically bridging O—P—O units and short Mn–O–P–O–Mn pathways for exchange. Keywords: polymeric manganese monophenylphosphinates, crystal structures, magnetic properties.

Crystal Structure of Dibromo(η4-1,5-cyclooctadiene)palladium(II)

1996 ◽  
Vol 61 (9) ◽  
pp. 1335-1341 ◽  
Author(s):  
Petr Štěpnička ◽  
Ivana Císařová
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
Square Planar ◽  
Twisted Boat

The crystal structure of [(η4-C8H12)PdBr2] has been determined by a single crystal X-ray diffraction with R = 3.82% for 2 147 independent diffractions. The compound crystallizes with the symmetry of orthorhombic space group P212121 (No. 19) within the following parameters: a = 7.0785(5) Å, b = 11.1896(9) Å, c = 12.514(1) Å, V = 991.2(1) Å3, Z = 4. The square planar arrangement of ligands around Pd(II) is distorted due to the steric requirements of 1,5-cyclooctadiene in a twisted boat conformation. Formula units are joined by the weak C2-H2...Br1(1 + x, y, z) hydrogen bonds.

Syntheses and reactivity of square-planar Rh(I) complexes, LRh(CO) (L = unsymmetric tridentate chelating pyrazolylgallate ligand). X-ray crystal structures of [Me2Gapz(OCH2CH2NH2)]Rh(CO) and [Me2Gapz(OCH2CH2NMe2)]Rh(COMe)I (pz = pyrazolyl, N2C3H3)

1985 ◽  
Vol 63 (11) ◽  
pp. 3019-3026 ◽  
Author(s):  
Brenda M. Louie ◽  
Steven J. Rettig ◽  
Alan Storr ◽  
James Trotter
Keyword(s):  
Crystal Structures ◽  
Heavy Atom ◽  
Least Square ◽  
Insertion Reaction ◽  
Space Group ◽  
Physical Measurements ◽  
Square Planar ◽  
Migratory Insertion ◽  
Complex Crystal

The syntheses and characterization of a number of square-planar Rh(I) monocarbonyl complexes incorporating un-symmetrical, tridentate, pyrazolylgallate ligands in a meridional coordination mode are described. Oxidative addition reactions of these complexes are detailed and a facile migratory insertion reaction, following the addition of methyl iodide, has resulted in a five-coordinate square-pyramidal Rh(III) acetyl complex. Crystal structures of two compounds are presented, [Me2Gapz(OCH2CH2NH2)]Rh(CO) and [Me2Gapz(OCH2CH2NMe2)]Rh(COMe)I, and confirm the molecular arrangements predicted on the basis of other physical measurements. Crystals of the former are monoclinic, a = 10.212(2), b = 7.8484(5), c = 16.733(2) Å, β = 105.133(6)°, z = 4, space group P21/c; and those of the latter are monoclinic, a = 10.0960(11), b = 11.5352(8), c = 15.871(2) Å, β = 105.764(6)°, z = 4, space group P21/n. Both structures were solved by conventional heavy atom methods and were refined by full-matrix least-square procedures to R = 0.026 and 0.036, respectively, for 2142 and 2941 reflections with I ≥ 3σ(I).

Structural studies of organoboron compounds. XIX. 1,7-Dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane

1984 ◽  
Vol 62 (3) ◽  
pp. 515-520 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Least Squares ◽  
Variable Temperature ◽  
Direct Methods ◽  
Structural Studies ◽  
Organoboron Compounds ◽  
Full Matrix ◽  
Space Group ◽  
H Nmr ◽  
Valence Tautomers

Crystals of 1,7-dimethyl-3,5-diphenyl-2,4,6-trioxa-7-aza-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane are triclinic, a = 10.559(2), b = 15.156(3), c = 10.338(2) Å, α = 99.14(1), β = 89.90(1), γ = 96.73(1)°, Z = 4, space group [Formula: see text]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.032 and Rw = 0.038 for 2396 reflections with I ≥ 3σ(I). The structure consists of two crystallographically independent, but virtually identical, molecules containing sterically lengthened N—B coordinative bonds (mean 1.740(3) Å). The structurally inequivalent (in the solid state) pairs of N-methyl and B-phenyl groups are observed by variable temperature 1H nmr to be magnetically equivalent in solution, implying a rapid interconversion of "valence tautomers" at temperatures down to −60 °C.

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