Matrix isolation ESR and theoretical studies of metal phosphides

Abstract

The ZnP, (67)ZnP, CdP, (111)CdP, and (113)CdP radicals have been formed by laser ablation of the metal with GaP pressed into the metal surface, isolated in an inert neon matrix at 4.3 K and their electronic structure was established using electron spin resonance spectroscopy. The following magnetic parameters were determined experimentally for ZnP/(67)ZnP, g(⊥)=1.9982(2), A(⊥)(P)=111(6) MHz, A(⊥)((67)Zn)=160(2) MHz, and D=-29 988(3) MHz and estimates were made for the following ZnP/(67)ZnP magnetic parameters: g(∥)=1.9941(2), A(∥)(P)=-5(6) MHz, and A(∥)((67)Zn)=180(50) MHz. The following magnetic parameters for CdP/(111)CdP/(113)CdP were determined experimentally: g(⊥)=1.9963(2), A(⊥)(P)=97(3) MHz, A(⊥)((111)Cd)=862(3) MHz, and A(⊥)((113)Cd)=902(3) MHz. Evidence for the formation of the MgP radical was also obtained and an approximate hyperfine coupling constant of A(⊥)(P)=157(6) MHz was determined. The low-lying electronic states of ZnP and MgP were also investigated using the multiconfigurational self-consistent field technique. Potential energy surfaces, binding energies, optimized bond lengths, energy separations, and dissociation energies have been determined. Both radicals are found to have (4)Σ(-) ground states with a leading configuration at r(e) of 10σ(2)11σ(2)5π(1)5π(1)12σ(1) for ZnP and 7σ(2)8σ(2)3π(1)3π(1)9σ(1) for MgP. Significant mixing to this state is calculated for MgP.

Matrix Isolation ESR and Theoretical Study of ZnN

“…This calculation for ZnN indicated that the 10σ was at a lower energy than the two 4π orbitals. A similar ordering was seen for MgN, 6 whereas for MgP and ZnP, 15 the opposite order was predicted. Although in each case, all three orbitals are very close to each other in energy.…”

“…Two similar radicals with 4 ∑ − ground states have been studied with matrix isolation ESR spectroscopy, the MgN radical, 6 and the ZnP radical. 15 The |D| value for the ZnN molecule (7268 MHz) is slightly lower than that of MgN (9797 MHz) and far lower than that of ZnP (29 988 MHz). The difference between ZnN and MgN is likely due to reduced spin−spin interaction from the longer Zn−N bond overruling any increase in the spin−orbit interaction due to the heavier zinc nucleus.…”

“…, 88 Si 2 + , and Ge 2 + , 9 BC, 10 AlC, 11 GaP + , 12 GaAs + , 13 SiB, and SiAl, 14 and ZnP and CdP. 15 Boldeyrev and Simons 16 have conducted ab initio theoretical calculations on ZnN. They found the ground state to be a 4 ∑ − radical bound only by a weak van der Waals interaction, with the excited 2 Π i state with a stronger bond.…”

“…ASSOCIATED CONTENT * S Supporting InformationThe Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpca.9b00601. TableS1, which presents the observed and simulated line position for Zn15 N and 67 Zn 14 N, and TableS2, which compares the calculated atomic dissociation energy for the various states of ZnN shown inFigure 5 (PDF) ■ AUTHOR INFORMATION Corresponding Author *E-mail: allan.mckinley@uwa.edu.au. Tel.…”

“…The magnetic quantum number for the N (I = 1) nucleus or the15 N (I = 1/2) nucleus. b Peak positions as measured at the apex.…”