Conductive molecular crystals. Structural, electrical, and magnetic properties of partially oxidized octamethyltetrabenzporphyrinatonickel(II)

Phillips, Terry E.; Scaringe, Raymond P.; Hoffman, Brian M.; Ibers, James A.

doi:10.1021/ja00530a022

Cited by 100 publications

(23 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, it has been assumed that the ratio between ligand 7~ and metal 3d contributions to the conduction processes is temperature dependent. This behavior differs from phenomenologically derived models for the carrier dynamics in, for example, Ni(0MTBP)I [21] or in Ni phthalocyanine polymers [lS], which belong to the class of organic metals with ligand-based transport properties.…”

Section: Physical and Chemical Properties Of Porphyrinatonickei(i1) Dmentioning

confidence: 61%

“…The resonance Raman spectrum of the molecular metal shows that the iodine is present in the form of 1; ions; the ionicity or the degree of oxidation of the macrocycle is thus p = +0.33, for example, 0.33 electrons per Ni(TBP) moiety have been transferred to the halide acceptor. In the octamethyl (OM) derivative of 1, Ni(OMTBP), a second oxidation product has been detected that corresponds to p = +0.97 [21]. Ni(TBP)I BOHM crystallizes in the space group D f h -P4/mcc in a columnar structure where planar Ni(TBP) units are stacked metal-over-metal; the NiNi spacing amounts to 3.217 A at 113°K and to 3.260 8, at room temperature.…”

Section: Physical and Chemical Properties Of Porphyrinatonickei(i1) Dmentioning

confidence: 99%

“…Ni(TBP)I belongs to the interesting group of 1D conductors with All parameters (0.66-1.3 times the unit cell dimension) at the boundary where the charge transport is determined either by diffuse hopping (All< 1) or where conduction phenomena can be explained on the basis of a band structure description (All> 1) [51]. Ni(OMTBP)I, on the other hand, belongs to the class of polaronic conductors where the mean free path of the charge carriers is much smaller than the intermolecular spacing (0.04) [21]. All of Ni(TBP)I is comparable with the mean free path of carriers in the isostructural phthalocyanine derivative [18], it exceeds All in TCP chains (0.6) [4] and in the TTF-TCNQ system (0.4-0.6) [52].…”

Section: Physical and Chemical Properties Of Porphyrinatonickei(i1) Dmentioning

confidence: 99%

See 2 more Smart Citations

The band structure of porphyrinatonickel(II). A semiempirical crystal orbital study based on the tight‐binding formalism

Böhm

1984

Int J of Quantum Chemistry

View full text Add to dashboard Cite

The band structure of porphyrinatonickel(I1) (2) has been studied by means of crystal orbital calculations that are based on the tight-binding approximation; the computational framework is a recently developed INDO model for transition metal compounds of the 3d series. The porphyrinato polymer has been studied in an eclipsed arrangement (2a) and in a staggered conformation (2b) where neighboring layers are rotated by 41". The total energy of the nietallomacrocycle has been decomposed into one-and two-center contributions; the latter interaction parameters have been fragmented into physically feasible resonance, exchange, and classical electrostatic (electron-electron, electron-core, core-core) interactions. It is shown that individual two-center potentials between atoms in neighboring layers are prevailingly determined by the electrostatic interaction energy. The NiNi coupling in the chain is highly repulsive; important stabilizing interactions are predicted between the 3d center of one cell and the electronegative N atoms in the neighboring layers. Stabilizing and destabilizing electrostatic interaction potentials largely compensate each other; the net stabilization in the polymer comes from the accumulation of resonance and exchange increments. The unoxidized Ni(I1) porphyrinato polymer is an insulator. Several ligand bands ( v , a, and lone-pair) are predicted on top of bands with significant Ni 3d admixtures; the conduction band of the unoxidized strand is of ligand T* character. The dense manifold of ligand states in the vicinity of the Ni 3d states (3d,2, 3d,2LY2, 3dx,/3dy,) prevents the formation of bands in the polymer that are strongly localized at the 3d center. Ni 3d,z and 3dX2-,2 interact strongly with ligand lone-pair and u states. Avoided crossings between E ( k ) curves in k space lead to compositions in the various bands that differ significantly at the bottom and the top. The INDO crystal orbital formalism predicts a partial oxidation of ligand bands in derivatives of 2 that contain oxidants (e.g., halides). The theoretical findings derived for 2 are compared with available experimental data on highly conducting porphyrinatonickel(I1) polymers (tetrabenzo and octamethyltetrabenzo derivatives of 2).

show abstract

Section: Physical and Chemical Properties Of Porphyrinatonickei(i1) Dmentioning

confidence: 61%

Section: Physical and Chemical Properties Of Porphyrinatonickei(i1) Dmentioning

confidence: 99%

Section: Physical and Chemical Properties Of Porphyrinatonickei(i1) Dmentioning

confidence: 99%

See 1 more Smart Citation

The band structure of porphyrinatonickel(II). A semiempirical crystal orbital study based on the tight‐binding formalism

Böhm

1984

Int J of Quantum Chemistry

View full text Add to dashboard Cite

show abstract

“…These in turn led to the study of semi-conductivity, photoconductivity, photochemical reactions, photosynthetic and electrocatalytical activities, etc. [3][4][5][6][7]. An important theme has been to determine the influence of axial or equatorial ligands on the physico-chemical properties of the complexes [8][9][10][11].…”

Section: Metallophthalocyaninesmentioning

confidence: 99%

Ir and Uv-Visible Spectra of Iron(ii) Phthalocyanine Complexes With Phosphine or Phosphite

Zanguina

Bayo-Bangoura

Bayo

et al. 2002

Bull. Chem. Soc. Eth.

View full text Add to dashboard Cite

ABSTRACT.We have prepared and studied by vibrational and electronic spectrometry of a series of ferrophthalocyanine complexes with phosphine or phosphite axial ligands [PMe3, P(OMe)3, PPh3, P(OPh)3, PPh(OMe)3 and POH(OEt)2]. With PMe3, P(OMe)3 as ligands, only hexacoordinated complexes are obtained but with PPh3, P(OPh)3 and POH(OEt)2 as ligands, the coordination number depends on the FePc:ligand ratio in the reaction mixture. In the ratio 1:1 the complexes thus formed are pentacoordinated and in the ratio 1:2 hexacoordinated complexes are obtained. In the electronic spectra of hexacoordinated complexes, two charge-transfer transition bands, one at ~375 nm and the other at ~421 nm can be observed. We attribute the band at 375 nm to charge-transfer from axial ligand to macrocycle (CT Lax ® Pc) and the band at 421 nm to charge-transfer from metal to axial ligand (CT Fe ® Lax). In the IR spectra, the position of the nFeN4 band is linked to the coordination number; in the spectra of pentacoordinated complexes, its frequency is almost the same as that in the FePc spectrum but in hexacoordinated complexes, it moves to high frequencies.

show abstract

“…This allows the electrons to move freely along the chain, making KCP a good one-dimensional metal. Certain Ni salts, on the other hand, when oxidized are conductive too, but the conduction appears to be ligand based [9]. This suggests that the Fermi level lies in the T band, which is mixed to some extent with the d,, and d,, orbitals of the metal.…”

mentioning

confidence: 99%

Criteria for the design of an excitonic superconductor

Little

2009

Int. J. Quantum Chem.

View full text Add to dashboard Cite

The Bardeen, Cooper, and Schrieffer (BcS) theory of superconductivity has provided an understanding of virtually all phenomena associated with the superconducting state. In recent years, great progress has been made in extending some aspects of this understanding to other types of ordered states, particularly in quasi-one-dimensional systems. This growth of understanding allows one to reexamine the question whether or not higher temperature superconductivity of the excitonic variety might be realized in these or other systems. We show first what the general conditions are for superconductivity in these systems, and then propose a specific type of polymeric structure, in which sufficiently strong excitonic interactions can be expected to lead to interesting behavior.In this article we will discuss some of the factors which determine the maximum temperature at which superconductivity can occur; and what progress has been made towards designing so called excitonic systems of organic or metallo-organic polymeric compounds, which should superconduct at relatively high temperatures, at or near room temperature.During the past two decades great interest has focused on the practical uses of superconductivity. First, in large-scale applications in magnets, power lines, motors, and generators and, second, in more subtle applications as magnetometers, microwave detectors, mixers, comparators, current sensors, and Josephson logic devices. All these devices require for their operation a costly low temperature environment-hence, the incentive to find superconducting materials with higher transition temperatures. The search for such materials and the problems which determine the direction one should go in the search require an understanding of many subtle features of solid state physics and chemistry.If one cools a metal, its electrical resistivity falls until one reaches a temperature of 20-30 K, where the resistivity reaches a value determined by the purity of the metal and crystalline perfection. For some metals, upon further cooling, a precipitous drop occurs in the resistivity at a well defined temperature, the transition temperature T,, which marks the transition to the superconducting state. This phenomenon is remarkably common, occurring in 26 elements at ambient pressure and another 10 at higher pressures [l]. In addition, some 10,000 alloys are known which superconduct-many of which involve or are composed of nonsuperconducting elements [2]. The transition temperatures of these alloys range from temperatures in the millikelvin range to 23.2 K for Nb3Ge. Most lie in the range 0-6 K. Substantial progress has been made during the past 25 years in pushing the maximum T, higher and higher. The questions International Journal of Quantum Chemistry: Quantum Chemistry Symposium 15,545-554 (1981) 0

show abstract

Conductive molecular crystals. Structural, electrical, and magnetic properties of partially oxidized octamethyltetrabenzporphyrinatonickel(II)

Cited by 100 publications

References 10 publications

The band structure of porphyrinatonickel(II). A semiempirical crystal orbital study based on the tight‐binding formalism

The band structure of porphyrinatonickel(II). A semiempirical crystal orbital study based on the tight‐binding formalism

Ir and Uv-Visible Spectra of Iron(ii) Phthalocyanine Complexes With Phosphine or Phosphite

Criteria for the design of an excitonic superconductor

Contact Info

Product

Resources

About