Tetracyanonickelate(II) compounds of some (tetraazamacrocycle)nickel(II) cations. The structure of catena-Di(μ-cyano)dicyano(N-meso-5,7,7,12,14,14-hexamethy1-1,4,8,11-tetraazacyclotetradeca-1, 11-diene)dinicke1(II) hydrate

1984 ◽  
Vol 37 (9) ◽  
pp. 1799 ◽  
Author(s):  
GJ Gainsford ◽  
NF Curtis
Keyword(s):  
Infrared Spectra ◽  
Ground State ◽  
Singlet Ground State ◽  
Ring Size ◽  
Triplet Ground State ◽  
Coordination Environment ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
A Chain ◽  
Tetracyanonickelate Compounds

Tetracyanonickelate(II) compounds of several (tetraazamacrocycle)nickel(II) cations have been prepared. The structure of the N-meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca- 4,11-diene, hmtd, compound [Ni(hmtd)Ni(CN)4].H2O has been determined by X-ray diffractometry [monoclinic, a 1780.3(3), b 1063.41(7), c 1409.3(2) pm, β 120.54(1)�, 24, space group C2/c, R 0.021, Rw 0.030 for 2178 reflections] and shows a chain polymeric structure with trans singlet ground state [Ni(CN)4]2- groups linking parallel stacked triplet ground state [Ni(hmtd)]2+ groups. The triplet ground state nickel(II) ions have a tetragonally elongated coordination environment [Ni-N (mean macrocycle) 204.5(1) pm, Ni-N (N≡C) 220.7(1) pm]. Tetracyanonickelate compounds of macrocycles related to hmtd but with different substituents, macrocycle ring size, and/or numbers of imine and amine donor groups were prepared. Some are diamagnetic, with discrete cation and anion, while others are similar to the hmtd compound, and for the latter, tetragonal distortions were evaluated from the reflectance spectra. Magnetic susceptibilities and infrared spectra are reported.

Compounds of Nickel(II) and Copper(II) With 3,5,5,13,13,15-Hexamethyl-1,2,6,9,12-pentaazacyclopentadeca-2,15-diene

1987 ◽  
Vol 40 (12) ◽  
pp. 1941
Author(s):  
NF Curtis ◽  
KR Morgan
Keyword(s):  
Ground State ◽  
Singlet Ground State ◽  
Amino Ketone ◽  
Triplet Ground State ◽  
Magnetic Susceptibilities ◽  
Kinetics Of ◽  
Formation Of Complexes

Reaction of the bis-β-amino ketone 4,4,12,12-tetramethyl-5,8,11-triazapentadecane-2,14-dione diperchlorate with nickel(II) or copper(II) in the presence of hydrazine results in the formation of complexes of the tetradentate pentaaza macrocycle 3,5,5,13,13,15-hexamethyl-1,2,6,9,12-pentaazacyclopentadeca-2,15-diene hpd. Singlet ground state [Ni( hpd )] (ClO4)2, triplet ground state [Ni( hpd )(NCS)2], [Ni( hpd )A] ClO4 (A = acac -, 1/2(C2O42-), NO2-1,[Ni( hpd )(NO3)] NO3 and [Cu( hpd )](C1O4)2 were prepared. Infrared, electronic, 1H and 13C n.m.r. spectra, magnetic susceptibilities, and the kinetics of the slow acid promoted aquation reactions of the cations at 25�C in HCl/NaCl solutions (I= 1 mol 1-1) are reported.

Preparation, and complexes with nickel(II) and copper(II), of a diazepane amine alcohol. The structure of [4,4-dimethyl-7-(5,5,7-trimethyl-1,4-diazepan-1-yl)-5-azaheptan-2-ol]nickel(II) perchlorate

1983 ◽  
Vol 36 (7) ◽  
pp. 1341 ◽  
Author(s):  
KR Morgan ◽  
GJ Gainsford ◽  
NF Curtis
Keyword(s):  
Ground State ◽  
Coordination Compounds ◽  
Major Product ◽  
Boat Conformation ◽  
Singlet Ground State ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Donor ◽  
Square Planar ◽  
Coordination Plane

Reduction of 4,4,12,12-tetramethyl-5,8,11-triazapentadecane-2,14-dione diperchlorate by sodium borohydride yields as the major product one isomer of 4,4-dimethyl-7-(5,5,7-trimethyl-1,2-diazepam 1-yl)-5-azaheptan-2-ol, pyaz. The coordination compounds [M(pyaz)] (ClO4), and [Ni(pyaz)(NCS)] CNS (M = NiII, CuII) were prepared, the latter being assigned five-coordinate structures. The structure of singlet ground state [Ni(pyaz)] (ClO4)2 was determined by X-ray diffraction [space group P212121, Z 4, a 1450.8(2), b 1522.2(1), c 1048.5(1) pm, R 0.0675, Rw 0.0768 for 2461 reflections]. The compound has a square-planar coordination arrangement, with the three nitrogen and the oxygen donor atoms of the pyaz ligand approximately coplanar [Ni-O 190.0(6) pm; Ni-N 192.8(6), 189.2(6), 189.2(6) pm in sequence N(5) of chain, N(l), N(4) of diazepane]. The diazepane ring adopts a boat conformation. One side of the nickel(II) coordination plane is sterically crowded by the presence of two axial methyl substituents. The ligand has two non-equivalent chiral centres (C(14) of the diazepane ring and C(2) of the amine alcohol chain), both present in the R configuration in the crystal studied. The three nitrogen atoms, which became chiral centres upon coordination, are present in the S configuration for two diazepane nitrogen atoms and in the R configuration for the 5-aza chain nitrogen.

Studies of Some Tetraazacyclopentadecadiene Complexes of Nickel(II). The Crystal and Molecular-Structure of (1RS,8SR)-(5,7,7,13,15,15-Hexamethyl-1,4,8,12-Tetraazacyclopentadeca-4,1 2-Diene)Nickel(II) Perchlorate Hydrate

1986 ◽  
Vol 39 (10) ◽  
pp. 1509 ◽  
Author(s):  
NF Curtis ◽  
GJ Gainsford
Keyword(s):  
Molecular Structure ◽  
Ground State ◽  
Crystal And Molecular Structure ◽  
Macrocyclic Ligand ◽  
Isomeric Form ◽  
Monoclinic Space Group ◽  
Singlet Ground State ◽  
Triplet Ground State ◽  
Square Planar ◽  
Coordination Plane

The crystal and molecular structure has been determined by X-ray diffractometry for the singlet ground state nickel(II) compound of a fifteen- membered tetraaza macrocyclic ligand , formed by reaction of a mixture of tris ( ethanediamine )nickel(II) and tris (propane-1,3- diamine )nickel(II) perchlorates with acetone. The compound, (1RS,8SR)- 5,7,7,13,15,15-hexamethyl-1,4,8,12-tetraazacyclopentadeca-4,12- diene )nickel(II) perchlorate hydrate, [Ni( hmpd )](ClO4)2.H2O, is monoclinic, space group P21/C, a 1158.76(14), b 1319.53(22), c 1630.35(21) pm, β 96.209(10)°, R 0.046, Rw 0.062 for 2798 reflections. The nickel(II) ion is in tetrahedrally distorted square-planar coordination [mean Ni-N distances 188.9 pm ( imine ), 191.9 pm (amine), displacements of nitrogens c. �20 pm from mean coordination plane]. Triplet ground state compounds [Ni( hmpd )( acac )]ClO4 and [{Ni( hmpd )}2C2O4](ClO4)2, with the macrocycle in folded coordination, were prepared and converted into an isomeric form of [Ni( hmpd )](ClO4)2. The 3,5,7,7,13,15,15-heptamethyl homologue of [Ni( hmpd )]2+ was prepared by reaction of tris (propane-1,2-diamine)- and tris (propane-1,3-diamine)- nickel(II) perchlorates with acetone. The electronic (d-d), 1H N.M.R. and 13C N.M.R . spectra of compounds of these macrocyclic cations, and of (5,5,7,13,15,15-hexamethyl-1,4,8,12-tetraazacyclopentadeca-7,12-diene) nickel(II) are reported.

Nickel(II) and copper(II) complexes of the macrocyclic ligand 5,7,7-Trimethyl-1,4,8,11-tetraazacyclotetradec-4-ene

1975 ◽  
Vol 28 (2) ◽  
pp. 275 ◽  
Author(s):  
NF Curtis ◽  
TN Milestone
Keyword(s):  
Ground State ◽  
Macrocyclic Ligand ◽  
Mesityl Oxide ◽  
Singlet Ground State ◽  
Triplet Ground State ◽  
Diacetone Alcohol ◽  
Square Planar

Nickel(II) and copper(II) complexes of 1,4,8,11-tetraazaundecane, (L), react with acetone, diacetone alcohol or mesityl oxide to form complexes of the macrocyclic ligand 5,7,7-trimethyl-1,4,8,11-tetra- azacyclotetradec-4-ene. For the nickel(II) cation, singlet ground state, square planar, salts are formed with poorly coordinating anions such as tetrachlorozincate, and triplet ground state, pseudoocta- hedral compounds with coordinating anions. These occur as trans compounds (macrocycle in planar coordination) for the unidentate anions NCS-, N3- and Cl- and as cis compounds (macrocycle in folded coordination)for the chelating anions acetylacetonate and oxalate. Different configurations of the chiral nitrogen centres are optimum for planar and for folded coordination of the macrocycle.

Compounds of Nickel(II) With trans-6,13-Dinitro- and trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane, with Structural Studies of Five (trans-6,13-Diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II) Compounds

1993 ◽  
Vol 46 (6) ◽  
pp. 755 ◽  
Author(s):  
NF Curtis ◽  
GJ Gainsford ◽  
A Siriwardena ◽  
DC Weatherburn
Keyword(s):  
Rate Constant ◽  
Catalytic Hydrogenation ◽  
Ground State ◽  
Macrocyclic Ligand ◽  
Singlet Ground State ◽  
Structural Studies ◽  
Nacl Solution ◽  
Triplet Ground State ◽  
Square Planar ◽  
Acid And Base

Compounds of NiII with the macrocyclic ligand trans-6,13-dimethyl-6,13-dinitro-1,4,8,11-tetraazacyclotetradecane ( dino ), which is formed by condensation of bis (ethane-1,2-diamine)nickel(II) salts, nitroethane and formaldehyde, are described, together with homologues formed by substituting propane-1,2-diamine and/or 1-nitropropane. The nitro functions of [Ni( dino )]2+ were reduced by catalytic hydrogenation to form (trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II), [Ni( diam )]2+, isolated as approximately equal amounts of two isomeric forms; designated α (with the R,S,R,S configuration of the chiral nitrogen centres, overall configuration 1α,4α,6β,8α,11α,13α), and β (with the R,R,S,S, 1α,4β,6α,8β,11α,13β configuration). The α-isomer is metastable, and in solution isomerizes to the β-isomer, with rate constant of 5.0(5)×10-5 s-1 in 2 mol l.-1. NaCl solution at 50°C, the rate of this reaction increasing in both acid and base. Protonation constants (pK at 25°C in 0.1 mol l.-1 NaClO4) for diam are 11.2(1), 9.7(1), 6.2(1), 5.3(1), and for the isomeric nickel(II) cations are α 4.94(2), 2.4(5); and β 4.5(1), 4.0(1). Compounds of diam with the β-configuration were prepared with triplet ground state NiII with diam in hexadentate coordination (e.g. β-[Ni(diam-N4)] Cln ) and in tetradentate coordination with the neutral (e.g. trans-β-[Ni(diam-N4)(NCS)2]) or diprotonated ligand (e.g. trans-β-[Ni(diamH2-N4)(NCS)2](CNS)2). Compounds prepared with the α-configuration with triplet ground-state NiII had pentadentate diam with the neutral (e.g. trans-α-[Ni(diam-N5)(H2O)]Cl2) or monoprotonated ligand (e.g. trans-α-[Ni(diamH-N5) Cl ] (ClO4)2). Singlet ground-state NiII compounds with the square planar diprotonated ligand were prepared for both configurations. Structures are reported for β-[Ni(diam-N6)](ClO4)2(H2O), R 0.062 for 5708 reflections; β-[Ni(diam-N6)] [ZnCl4].1.5H2O, R 0.064 for 4332 reflections; β-[Ni(diam-N6)]Cl2.6H2O, R 0.044 for 2001 reflections; trans-β-[Ni(diam-N4)(NCS)2] R 0.056 for 1521 reflections; and trans-α-[Ni(diamH-N5) Cl ](ClO4)2(H2O), R 0.047 for 2667 reflections.

scholarly journals Strategies for Computer-Aided Discovery of Novel Open-Shell Polymers

2021 ◽  
Author(s):  
Omri Abarbanel ◽  
Julisa Rozon ◽  
Geoffrey Hutchison
Keyword(s):  
Ground State ◽  
Conjugated Polymer ◽  
Density Functional ◽  
Singlet State ◽  
Density Functional Theory Calculations ◽  
Open Shell ◽  
Singlet Ground State ◽  
Functional Theory ◽  
Triplet Ground State ◽  
Homo Lumo

Organic π-conjugated polymers with a triplet ground state have been the focus of recent research for their interesting and unique electronic properties, arising from the presence of the two unpaired electrons. These polymers are usually built from alternating electron-donating and electron-accepting monomer pairs which lower the HOMO-LUMO gap and yield a triplet state instead of the typical singlet ground state. In this paper we use density functional theory calculations to explore the design rules that govern the creation of a ground state triplet conjugated polymer, and find that a small HOMO-LUMO gap in the singlet state is the best predictor for the existence of a triplet ground state, compared to previous use of pro-quinoidal character. This work can accelerate the discovery of new stable triplet materials by reducing the computa- tional resources needed for electronic-state calculations and the number of potential candidates for synthesis.

Compounds of 3,4,7,9,9,14,16-Octamethyl- (and 7,9,9,14,14,16-Hexamethyl-3,4-diphenyl) 1,2,5,6,10,13-Hexaazacyclohexadeca-2,4,6,16-tetraene With Nickel(II) and Copper(II). Preparations and Kinetics of Acid Hydrolysis Reaction

1988 ◽  
Vol 41 (11) ◽  
pp. 1665 ◽  
Author(s):  
NF Curtis
Keyword(s):  
Ground State ◽  
Metal Ion ◽  
Order Rate Constant ◽  
Singlet Ground State ◽  
Triplet Ground State ◽  
First Order ◽  
Order Rate ◽  
Ion Substitution ◽  
Kinetics Of ◽  
Hydrolysis Of

The complex nickel(II) cation of the bis-diazine macrocycle 3,4,7,9,9,14,14,16-octamethyl-1,2,5,6,10,13-hexaazacyclohexadeca-2,4,6,16-tetraene, omht, is formed by reaction of the complex of 3,3,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dihydrazone with butane-2,3-dione, and the complex of the 7,9,9,14,14,16-hexamethyl-3,4-diphenyl homologue, bzht, is similarly prepared by reaction with 1,2- diphenylethane-1,2-dione. The cation [Cu(hmtd)]2+ is formed by metal ion substitution for a precursor of the nickel(II) cation. Compounds of the nickel(II) cations occur as singlet ground state perchlorate salts, or as triplet ground state octahedral compounds with additional ligands, e.g. [Ni(omht)(NCS)2], [{Ni(omht)(N3)}2](ClO4)2 and [Ni(omht)(en)] (ClO4)2. The singlet ground state [Ni(omht)]2+ cation in dimethyl sulfoxide converts into a triplet ground state species with first-order rate constant of 2.1(2)×10-6 s-1 at 25°C, 5.1(2)×10-5 s-1 at 50°C. The cations are slowly hydrolysed by acid, and pseudo-first-order rate constants in 2 mol l-1 HCl/NaCl for hydrolysis of [Ni(omht)]2+ and [Cu(omht)]2+ at 25° and 50°C are reported. These are of the order of 10-5 (25°C), 10-4(50°C) s-1, with a non-linear dependence on [H+], and with the reactions faster for the nickel(II) cation.

Compounds of the 16-Membered Macrocyclic Tetraamine (4RS,12RS)-2,2,4,10,10,12-Hexamethyl-1,5,9,13-tetraaza-cyclohexadecane with Cobalt(II), Nickel(II), Copper(II) and Zinc(II); Structural and Molecular Mechanics Studies

2000 ◽  
Vol 53 (9) ◽  
pp. 727 ◽  
Author(s):  
Neil F. Curtis ◽  
Olga P. Gladkikh
Keyword(s):  
Molecular Mechanics ◽  
Ground State ◽  
Boat Conformation ◽  
Singlet Ground State ◽  
X Ray Diffraction ◽  
Molecular Plane ◽  
X Ray ◽  
Counter Ions ◽  
Twist Boat ◽  
Chelate Rings

The cyclic tetraamine compound (4RS,12RS)-(2,2,4,10,10,12-hexamethyl-1,5,9,13-tetraazacyclohexadecane) nickel(II) perchlorate, [Ni(L1 )] (ClO4)2, has been prepared by reduction of the imine functions of (2,4,4,10,12,12-hexamethyl-1,5,9,13-tetraazacyclohexadeca-1,9-diene)nickel(II) by catalytic hydrogenation, or by NaBH4 in acetonitrile/methanol. The ligand L 1 was isolated, after reaction with acid, as the salt [(L 1 )H4](ClO4)Cl3·H2O. Compounds with cobalt(II), copper(II), and zinc(II) were prepared from this, and the structures of [M(L 1 )] (ClO4)2, M = Co, Ni and Cu, and [Cu(L 1 )] [ZnCl4], determined by X-ray diffraction: [Co(C18H40N4)] (ClO4)2, orthorhombic, Pn21/a, a 8.644(3), b 14.869(8), c 19.541(7) Å, Z 4, R1 0.062 for 99 reflections with I > 2s(I); [Ni(C18H40N4)] (ClO4)2, monoclinic, C2/c, a 11.780(4), b 12.580(4), c 16.930(3) Å, b 90.14(4)˚, Z 4, R1 0.067 for 1644 reflections with I > 2s(I); [Cu(C18H40N4)] (ClO4)2, monoclinic, C2/c, a 11.508(7), b 13.17(2), c 16.83(1) Å, b 92.37(5)˚, Z 4, R1 0.114 for 2366 reflections with I > 2s(I); [Cu(C18H40N4)] [ZnCl4], monoclinic, P21/n, a 9.392(3), b 14.915(6), c 17.591(7) Å, b 95.94(3)˚, Z 4, R1 0.041 for 2301 reflections with I > 2s(I). All have the C-rac, 1RS,4SR,5RS,9RS,12RS,13SR, configuration with N–H groups alternating on opposite sides of the molecular ‘plane’ around the ring. All have flattened tetrahedral coordination geometry, with the quartet ground state cobalt(II) cation most twisted and the copper(II) tetrachlorozincate, perchlorate and singlet ground state nickel(II) complex cations progressively more flattened. The macrocycles have overall saddle-like conformations with chelate rings tilted alternately to opposite sides of the molecular ‘plane’. The compounds all have both trimethyl-substituted chelate rings in chair conformations. The unsubstituted chelate rings both have chair conformations for the cobalt(II) compound, both have twist-boat conformations for the nickel(II) and copper(II) perchlorate salts and have one chair and one twist-boat conformation for the copper(II) tetrachlorozincate salt. Mean M–N distances (Å) and trans-N–M–N angles {N(1)–M–N(9), N(5)–M–N(13) (degrees)} are: Co, 1.99, 130.3(5), 115.5(5); Ni, 1.93, 163.6(4), 155.8(4); Cu (ClO4), 1.99, 155.0(6), 143.8(7); Cu (ZnCl4) 2.00, 146.6(2), 135.0(2). The influence of axial interactions with counter ions, hydrogen bonding and other lattice interactions on the structures adopted are discussed. Strain energies for the possible configurations/conformations of coordinated L 1 have been calculated by molecular mechanics and related to the observed structures.

Compounds of Copper(II) and Nickel(II) with 6,8,8,13,13,15-Hexamethyl-1,2,4,5,9,12- hexaazacyclopentadeca-5,15(1)-diene and Some 3-Substituted Homologues

1998 ◽  
Vol 51 (7) ◽  
pp. 611 ◽  
Author(s):  
Neil F. Curtis ◽  
Olga P. Gladkikh ◽  
David C. Weatherburn ◽  
John S. De Courcey ◽  
T. Neil M. Waters
Keyword(s):  
Metal Ions ◽  
Ground State ◽  
Mirror Symmetry ◽  
Macrocyclic Ligand ◽  
The Other ◽  
Singlet Ground State ◽  
Triplet Ground State ◽  
Square Planar

Copper(II) and nickel(II) compounds, [M(L)]2+, of the macrocyclic ligand 6,8,8,13,13,15-hexamethyl-1,2,4,5,9,12-hexaazacyclopentadeca-5,15(1)-diene are formed by reaction of compounds of 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dihydrazone with methanal. Analogous reactions with aldehydes RHCO, or ketones RR′CO, form compounds of 3-R or 3-RR′ substituted ligands, [M(r- L)]2+ or [M(rr′-L)]2+, respectively. The nickel(II) cations form singlet ground state salts, e.g. [Ni(L)]X2, X = [ClO4]- or ½[ZnCl4]2-, and also triplet ground state compounds, e.g. [Ni(L) (NCS)2] and [Ni(L)(X)] (ClO4) (X = NO2-, C2O42-, N3-, etc.). The structures of [Cu(L)] (ClO4)2, [Ni(L)] (ClO4)2, the 3-propyl compound formed from butanal, [Cu(pr-L)] (ClO4)2.H2O, and the compounds of 9,11,11,16,16,18-hexamethyl-7,8,12,15,19,20-hexaazaspiro[5.14]eicosa-8,18(1)-diene (chex-L), formed from cyclohexanone, namely [Cu(chex-L)] (ClO4)2.MeOH, [Ni(chex-L)] (ClO4)2, and [Ni(chex-L)] (ClO4)2.MeOH, were determined. All have the metal ions in tetrahedrally twisted square-planar coordination, by N1, N5, N9 and N12 , with N9N12-rac, for the (L) and (pr-L) compounds, or by the structurally equivalent N3, N7, N10 and N14, with N7N10-rac, for the (chex-L) compounds. The [Cu(L)]2+ and [Cu(pr-L)]2+cations have saddle-like macrocycle conformations, with approximate mirror symmetry, while the other compounds have ′twisted′ macrocycle conformations with approximate twofold symmetry {[Cu(L)] (ClO4)2, C15H32Cl2CuN6O8, orthorhombic,P 212121, a 8·562(7), b 13·096(8), c 20·257(6) Å, Z 4, R 0·041 for 1540 reflections; [Ni(L)] (ClO4)2, C15H32Cl2N6NiO8, orthorhombic, P21/n, a 13·500(3), b 9·207(2), c 19·478(5) Å, β 103·94(2)°, Z 4, R1 0·055 for 2650 reflections; [Cu(Pr-L)] (ClO4)2.H2O, C18H40Cl2CuN6O9, monoclinic, C 2, a 24·229(5), b 13·780(3), c 8·877(2) Å, β 108·79(3)°, Z 4, R1 0·067 for 1765 reflections; [Cu(chex-L)] (ClO4)2.MeOH, C21H44Cl2CuN6O9, monoclinic, C 2/c, a 17·086(5), b 24·539(2), c 14·496(1) Å, β 89·94(2), Z 8, R1 0·072 for 2521 reflections; [Ni(chex-L)] (ClO4)2, C20H40Cl2N6NiO8, monoclinic, P 21/c, a 14·820(2), b 18·599(4), c 10·282(1) Å, β 106·26(1)°, Z 4, R1 0·067 for 2552 reflections; [Ni(chex-L)] (ClO4)2.MeOH, C21H44Cl2CuN6O9, monoclinic, C 2/c, a 14·451(2), b 24·11(2), c 16·740(3) Å, β 90·14(1)°, Z 8, R1 0·064 for 2598 reflections}.

The coefficient of viscosity of atomic hydrogen from 25 to 300 °K

1962 ◽  
Vol 267 (1328) ◽  
pp. 102-118 ◽  
Keyword(s):  
Cross Sections ◽  
Ground State ◽  
Atomic Hydrogen ◽  
Phase Shifts ◽  
Wave Number ◽  
Rigid Sphere ◽  
Singlet Ground State ◽  
Triplet Ground State ◽  
Square Well ◽  
Coefficient Of Viscosity

The elastic scattering of two H atoms in the singlet ground state has been investigated on the basis of a deep square -well potential, bounded by the long -range van der Waals attrac­tion . Phase shifts with their appropr ate multiples of π are represented fo r L = 0 (1 ) 29. Some phase shifts exhibit a step -like gain of it within creasing wave number . This phenomenonis illustrated by wave function graphs and is discussed . Viscosity cross -sections are given . For scattering in the triplet ground state a Buckingham - Corner form of potential has been used and previously calculated cross -sections have been extrapolated and applied. Effective rigid -sphere diameters have been estimated by the empirical methodof Hirschfelder & Eliason , both for the approximate and accurate potentials . Two curves are given for the temperature dependence of the coefficient of vicosity , one calculated , the other estimated , and the true curve should lie nearer the latter.

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