Organotin compounds in agriculture since 1980. Part 2. Acaricidal,antifeedant, chemosterilant and insecticidal properties

The object of this review paper is to provide a guide to agrochemical research involving organotin compounds which has been performed since 1980. The information is presented in a tabular form and is divided into four main sections as indicated by the title. Each section is then subdivided to cover the various commercial organotin compounds. A final subsection lists investigations involving novel compounds. An additional section covers the effects of organotin agrochemicals on non-target organisms. A table of the contents has been provided to enable ease of reference. Acaricidal, antifeedant, chemosterilant and insecticidal properties are covered here. Fungicidal, bactericidal and herbicidal aspects are covered in Part 1.     

Positive muon spin depolarization in quenched aluminium dilute alloys

Aluminum dilute alloys (Al-0.047 at% Mg, Al-0.052 at% Cu and Al-0.051 at% Si) were quenched from 600 and 450C. The positive muon behavior in the quenched alloys has been studied. Three peaks (Peak I, II and III) are found. Peak I is due to the trapping and detrapping of positive muons at single impurity atoms. The muon spin depolarization rate at the trap in Peak I was found to be 0.36sec^–1. Peak II is connected to impurity clusters. Peak III is the trapping of muons at quenched-in vacancies. The depolarization rate at the trapping site was found to be 0.2sec^–1. The activation energy of the trapping rate was found to be 25 meV. As the quenched-in vacancies annealed out, the trapping rates decreased to near zero.     

μ +SR study of some magnetic superconductors

The relaxation of the ⁺SR signal has been investigated for the three compounds YRh₄B₄, ErRh₄B₄ and SmRh₄B₄. In the non-magnetic superconducting (T _c 11 K) YRh₄B₄, the data display a Kubo-Toyabe (gaussian) shape for zero (transverse) magnetic fields. ErRh₄B₄ (superconducting below 8.7 K and ferromagnetic below 1 K) shows a dominant signal with very slow relaxation. In contrast SmRh₄B₄ (superconducting below 2.7 K and antiferromagnetic-superconducting below 0.87 K) shows a change in relaxation from gaussian above 60 K to exponential between 1 K and 4 K to two exponential signals (fast and slow) belowT _N=0.9 K. In the region 0.9 K <T < 4.5 K, the relaxation time and the asymmetry both increase withT.supported by the U.S. Department of Energy.Supported by NSERC of Canada.supported by the U.S. Department of Energy.We are grateful to Drs. H. Umezawa and H. Matsumoto for interesting discussions regarding the persistent current screening and the results of self-consistent calculations.     

The preparation and tin-119m mössbauer spectra of tri-n-butylstannyl esters of heterocyclic and substituted aromatic carboxylic acids

The ^119mSn Mössbauer and infrared data are reported for fifteen tributyltin carboxylates. Although the Mössbauer data at 80 K shows them all to be pentacoordinate polymers, the infrared data indicates that, at room temperature, some of the compounds exist as tetracoordinate monomeric species.     

A random-walk simulation of flow-injection systems with merging zones

A flow-injection system with merging zones is simulated by using a random-walk stochastic (Markovian chain) model. Variables studied include reagent plug size and offset, reagent concentration and flow rate, injection delay time, reaction stoichiometry, rate constant, diffusion constants, viscosity, and temperature. The reaction of Ca(II) with o-cresolphthalein complexone was used to compare simulated and experimental results. In general, there was good agreement among computed and measured results.     

Kinetics of the reaction of atomic fluorine with phosphorous trifluoride: ESR determination

The reaction rate constant of the addition of atomic fluorine to excess PF₃ was determined by fast flow ESR measurements to be (8.6 ± 0.6) × 10¹² cm³ mole^?1 s^?1 at 300 K. The stoichiometry of the overall reaction of F with PF₃ was 2:1. Finite difference calculations simulating several reaction mechanisms suggest that the reaction occurs in two consecutive addition steps, F + PF₃ = PF₄ and F + PF₄ = PF₅. Assuming this mechanism is correct, the rate constant for the second reaction would be approximately (1.2 ± 0.2) × 10¹³ cm³ mole^?1 s^?1.     

On the Conformation and Structure of Organometal Complexes in the Solid State: Two Studies Relevant to Chemical Synthesis

Conformational preferences of two classes of organometal complexes have been surveyed by inspecting the Cambridge Structural Database (CSD). Lewis acid carbonyl complexes demonstrate a variety of coordination geometries, depending on the electronic and steric requirements of the carbonyl ligands and the nature of the Lewis acid. Similarly, the solid-state conformation of various π-bonding ligands in metal acyl, metal nitrosyl, metal acetylene, and metal imido complexes is revealed. These insights have stimulated the development of a conformational model that is based on considerations of π-bond hybridization and frontier molecular orbital theory. The analyses are relevant to the mechanism and transition structures of many synthetically important transformations. A deeper understanding of the conformational properties of organometal complexes, based on accurate structural information, will likely expedite the design and improvement of metal-mediated processes.     

Linearity of a flame ionisation detector for capillary gas chromatography

Summary The influence of the nitrogen and hydrogen flow rates on the linearity of the flame ionisation detector is investigated and flow-rates which give a linear response over five orders of magnitude are determined.     

Measurement of the breakup channels in nuclear muon capture by3He and4He

The rates of the breakup reactions _B(³He) and _B(⁴He) in nuclear muon capture by³He and⁴He have been measured. The measurements were performed on the muon beam of PSI with a multi-anode high-pressure ionization chamber filled with isotopically pure³He or⁴He at 120 bar. The chamber was used as a target and detector for both the incoming muons and for the charged reaction products (tritons, deuterons and protons) of the breakup reactions _B(³He) and _B(⁴He). Our statistics, about 5 × 10⁵ of breakup events, provides a possibility to improve the precision of evaluated rates. The preliminary results: _B(³He)=720 ± 70 s^–1, _B(⁴He)=415 ± 40 s^–1 are compared to theoretical predictions and to previous experiments.