scholarly journals Insights into the Observed trans-Bond Length Variations upon NO Binding to Ferric and Ferrous Porphyrins with Neutral Axial Ligands

ACS Omega ◽  
2021 ◽  
Author(s):  
Rahul L. Khade ◽  
Erwin G. Abucayon ◽  
Douglas R. Powell ◽  
George B. Richter-Addo ◽  
Yong Zhang
Keyword(s):  
Bond Length ◽  
Trans Bond ◽  
Axial Ligands

Kristall-und Molekülstruktur von N-(TricHorgermyl)-trimethylphosphinimin [Cl3Ge-N=PMe3]n, n = 1 und 2 / Crystal and Molecular Structure of N-(Trichlorogermyl)-trimethylphosphinimine [Cl3Ge-N=PMe3]n, n= 1 and 2

1978 ◽  
Vol 33 (5) ◽  
pp. 493-497 ◽  
Author(s):  
W. S. Sheldrick ◽  
D. Schomburg ◽  
W. Wolfsberger
Keyword(s):  
Molecular Structure ◽  
Bond Length ◽  
Crystal And Molecular Structure ◽  
Unit Cell ◽  
Centrosymmetric Dimer ◽  
Triclinic Space Group ◽  
Bond Lengths ◽  
Axial Ligands ◽  
Trigonal Bipyramidal ◽  
Coordinate Bond

Abstract N-(Trichlorogermyl)trimethylphosphinimine crystallizes in the triclinic space group P1̅ with a = 12.49(2), b = 12.54(3), c = 6.66(1) Å,a = 100.96(10),β = 91.45(14), γ = 102.77(15)°. The structure was solved by Patterson and difference syntheses and refined to R = 0.063 for 2867 independent reflections. In the unit cell there are two symmetry related monomers containing tetracoordinated Ge and one crystallographically centrosymmetric dimer with a planar four-membered [GeN]2 ring exhibiting trigonal-bipyramidal pentacoordinated Ge and trigonal N. Significant differences are observed in the bond lengths from pentacoordinated Ge to its equatorial and axial ligands: Ge-Neq 1.837(7), Ge-Nax 1.972(7), Ge-Cleq 2.176(2) and 2.170(2), Ge-Clax 2.345(3) Å. The Ge-Neq distance is similar to that observed in tetracoordinated derivatives [1.81-1.87 Å], whereas the Ge-Nax distance is 0.22 Å shorter than that observed for the axial N→Ge coordinate bond in hitherto known pentacoordinated derivatives [2.19-2.24 Å]. The very short Ge-N bond length of 1.737(8) Å in the monomer which is 0.07 Å shorter than in other tetracoordinated derivatives may be indicative of the involvement of a (p→d)π component.

The trans effect: methodological musings

1992 ◽  
Vol 70 (10) ◽  
pp. 2574-2601 ◽  
Author(s):  
Osvald Knop ◽  
S. C. Choi ◽  
David C. Hamilton
Keyword(s):  
Bond Length ◽  
Functional Relation ◽  
Data Sets ◽  
Length Variation ◽  
Trans Effect ◽  
Trans Bond ◽  
Present Context ◽  
Electronic Compensation ◽  
Chemical Trends ◽  
Equilibrium Geometries

The trans effect (TE) in the present context refers to the electronic compensation which in collinear homoligand L—Z—L* trans bond pairs lengthens the Z—L* bond when the Z—L bond is shortened. The existence of a functional relation d* = f(d) between the conjugated bond lengths d(Z—L) and d*(Z—L*) (d and d* not equivalent by symmetry; population A) has been demonstrated for a variety of Z-L combinations, with Z mostly from Groups VI and V and L mostly a halogen. The two model functions investigated in detail are the empirical DPF (difference power fit), d* – d0 = K(d − d0)−c, and the semiempirical CSBO (constant sum of bond orders) based on a modified 3-centre 4-electron bond concept, d* − d0 = −B ln {1 − expt[−(d − d0)/B]}, where B = b0 + b1(d − d0). Fitting DPF and CSBO to experimental d,d* data sets involves 3-parameter nonlinear optimization; in this CSBO differs from the 2-parameter treatment of Sheldrick etal., in which the limiting bond length d0 was supplied externally. Modified versions of DPF and CSBO have been devised to accommodate, along with A, d,d* pairs in which d = d* by symmetry (population S).The relative merits of DPF and CSBO and the various aspects of TE quantification are discussed at length, among these the effect of the oxidation state of Z and of the presence of heteroligands on Z. The meaning of the parameters of optimization and the existence of "chemical" trends between them are examined as well as the importance of the symmetrically balanced bond length de = d = d* and of the total d range Δ = de−d0 resulting from the d,d* regressions. Attempts to extend TE quantification to collinear heteroligand L1—Z—L2trans bond pairs have provided insight into the nature of the bond-length variation in such systems. The very good DPF and CSBO fits to d,d* sets obtained from 6-31G* optimizations of the equilibrium geometries of the OBOX, XOCN, and OCNY (X, Y = H, F, Cl, Li, Na, or no ligand) molecules and ions support the validity of the modified 3c4e model in accounting for the TE bond-length relationships.

A five-coordinate iron(III) porphyrin complex including a neutral axial pyridine N-oxide ligand

2019 ◽  
Vol 75 (6) ◽  
pp. 717-722
Author(s):  
Melanie A. Short ◽  
Roger D. Sommer ◽  
Alec J. Falzone ◽  
Tao Huang ◽  
Walter W. Weare ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Spin Crossover ◽  
Bond Angle ◽  
Organic Ligand ◽  
Binding Mode ◽  
Porphyrin Complex ◽  
Axial Ligands ◽  
Crossover Behavior ◽  
Porphyrin Core

While six-coordinate iron(III) porphyrin complexes with pyridine N-oxides as axial ligands have been studied as they exhibit rare spin-crossover behavior, studies of five-coordinate iron(III) porphyrin complexes including neutral axial ligands are rare. A five-coordinate pyridine N-oxide–5,10,15,20-tetraphenylporphyrinate–iron(III) complex, namely (pyridine N-oxide-κO)(5,10,15,20-tetraphenylporphinato-κ4 N,N′,N′′,N′′′)iron(III) hexafluoroantimonate(V) dichloromethane disolvate, [Fe(C44H28N4)(C5H5NO)][SbF6]·2CH2Cl2, was isolated and its crystal structure determined in the space group P\overline{1}. The porphyrin core is moderately saddled and the Fe—O—N bond angle is 122.08 (13)°. The average Fe—N bond length is 2.03 Å and the Fe—ONC5H5 bond length is 1.9500 (14) Å. This complex provides a rare example of a five-coordinate iron(III) porphyrin complex that is coordinated to a neutral organic ligand through an O-monodentate binding mode.

scholarly journals Bis(1-phenylimidazole)[5,10,15,20-tetrakis(2-pivalamidophenyl)porphinato]iron(III) trifluoromethanesulfonate chlorobenzene disolvate

IUCrData ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Jianfeng Li ◽  
Allen G. Oliver ◽  
W. Robert Scheidt
Keyword(s):  
Hydrogen Bonds ◽  
Bond Length ◽  
Dihedral Angle ◽  
Relative Orientation ◽  
Title Complex ◽  
Inversion Center ◽  
Axial Ligands ◽  
Phenyl Rings ◽  
Porphyrin Core ◽  
Oxygen Atoms

The title complex, [Fe(C64H64N8O4)(C9H8N2)2](CF3O3S)·2C6H5Cl, has an unusual relative orientation of the two planar axial ligands [dihedral angle between the two imidazole planes = 46.55 (9)°]. The average equatorial Fe—N bond length is 1.974 (3) Å; the axial distances are 1.9628 (19) and 1.9932 (19) Å. The porphyrin core displays modest ruffling. Disorder is modeled for three of the tert-butyl groups of the pickets. In the crystal, a modest π–π interaction exists between adjacent phenyl rings related by an inversion center, and hydrogen bonds connect the trifluoromethanesulfonate oxygen atoms to the amide groups of the picket substituents.

Crystal and Molecular Structure of N-(Trifluorosilyl)trimethylphosphinimine Dimer

1977 ◽  
Vol 32 (1) ◽  
pp. 22-25 ◽  
Author(s):  
W. S. Sheldrick ◽  
W. Wolfsberger
Keyword(s):  
Molecular Structure ◽  
Bond Length ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Bond Lengths ◽  
Axial Ligands ◽  
Trigonal Bipyramidal ◽  
Pentacoordinate Silicon

N-(Trifluorosilyl)trimethylphosphinimine dimer crystallises in the monoclinic space group P21/n, Z = 2, with a= 6.314(2), b = 12.057(5), c = 10.936(4) Å, β = 95.45(2)°. The structure was solved by direct methods and refined to R 0.078 for 1117 independent reflections. The molecule is dimeric and centrosymmetric with an planar four-membered [SiN]2 ring containing trigonal-bipyramidal pentacoordinate silicon and trigonal nitrogen. Significant differences are observed in the bond lengths from silicon to its equatorial and axial ligands: Si-Neq 1.736(4), Si-Nax 1.857(4), Si-Feq1.606(4) and 1.607(3), Si-Fax 1.668(3) Å. The Si-Neq bond length is similar to that in tetracoordinate derivatives for which a (p →d) π bonding component has been postulated, while the Si-Nax distance is very much shorter than that observed in other pentacoordinate derivatives.

Bond-length distributions for ions bonded to oxygen: Results for the lanthanides and actinides and discussion of the f-block contraction

2017 ◽  
Author(s):  
Olivier Charles Gagné
Keyword(s):  
Bond Length ◽  
Coordination Number ◽  
Lanthanide Ions ◽  
Lanthanide Contraction ◽  
Trivalent Lanthanide ◽  
Actinide Ions

Bond-length distributions have been examined for eighty-four configurations of the lanthanide ions and twenty-two configurations of the actinide ions bonded to oxygen. The lanthanide contraction for the trivalent lanthanide ions bonded to O<sup>2-</sup> is shown to vary as a function of coordination number and to diminish in scale with increasing coordination number.

Bond-length distributions for ions bonded to oxygen: Metalloids and post-transition metals

2017 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Ions ◽  
Bond Length ◽  
Lone Pair ◽  
Transition Metal Ions ◽  
Oxygen Lone Pair

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.

Bond-length distributions for ions bonded to oxygen: Metalloids and post-transition metals

2017 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Ions ◽  
Bond Length ◽  
Lone Pair ◽  
Transition Metal Ions ◽  
Oxygen Lone Pair

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.

Bond-length distributions for ions bonded to oxygen: Results for the non-metals and discussion of lone-pair stereoactivity and the polymerization of PO4

2017 ◽  
Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne
Keyword(s):  
Metal Ions ◽  
Bond Length ◽  
Lone Pair ◽  
Group 14 ◽  
Oxygen Lone Pair

Bond-length distributions are examined for three configurations of the H+ ion, sixteen configurations of the group 14-16 non-metal ions and seven configurations of the group 17 ions bonded to oxygen. Lone-pair stereoactivity for ions bonded to O<sup>2-</sup> is discussed, as well as the polymerization of the PO<sub>4</sub> group.

Sign in / Sign up

Export Citation Format

Share Document