AIC60674SStructural conclusions about complex ions formed from several imidazole derivatives, from which chelates could result if carbon-metal bonding occurred, have been deduced from N M R data and electronic absorption spectra. None of the ligands examined show evidence of formation of carbon-bound chelates with Co(1I) or Cu(I1). Less extensive studies with Ni(I1) and Fe(I1) also gave no evidence of carbon-bound species. Two crystalline substances, dichlorobis[ l-(2-pyridylmethyl)benzimidazole]cobalt and dichlorobis[ 1 -(2-pyridylmethyl)-4,5-dimethylimidazole]cobalt were examined by x-ray diffraction. Dichlorobis[ l-(2-pyridylmethyl)benzimidazole]cobalt crystallized from acetonitrile as blue crystals in the space group Pi with Z = 2, u = 10.314 (3) A, b = 11.458 (2) A, c = 12.442 (4) A, (Y = 63.37 ( 2 ) O , 0 = 74.58 (2)O, y = 82.17 (2)O, pcalcd = 1.45 g c K 3 , and pobsd = 1.43 g ~m -~. Least-squares refinement of 2600 independent reflections with F2 I 30(F2) gave a conventional R factor of 0.030. Dichlorobis[ l-(2-pyridylmethyl)-4,5-dimethylimidazole]cobalt crystallized from Me2SO-d6 as blue crystals in the space group P2,/c with 2 = 4, u = 8.343 (2) A, b = 16.982 (3) A, c = 19.297 (4) A, / 3 = 117.35 (2)O, pmId = 1.38 g ~m -~, and pOM = 1.39 g ~m -~. Least-squares refinement of 3121 independent reflections with F2 L 3n(F2) gave a conventional R factor of 0.036. In both cases, the Co2+ ion was tetrahedrally coordinated by C1-ions and by two organic ligands coordinated via the imidazole nitrogen in agreement with the conclusions drawn from solution data. 1, R4, R5 = H 6 , R 4 , R 5 = H 9 2, R4 =CH,, R5 = H 3, R4 = H, R5 = CH, 4, R4, R5 = CH, 5, R4, R5 = benzo

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The compounds formed by the reaction of the group 5A Lewis bases trimethylphosphine, trimethylarsine, and trimethylstibine with the simple boron Lewis acids boron trifluoride, boron trichloride, boron tribromide, diborane, and trimethylborane have been characterized by NMR, ir-Raman spectroscopy, mass spectrometry, conductivity, tensimetric titration, gas-phase displacement reactions, and melting point determinations. The expected one-to-one adducts were formed in most cases; however, trimethylborane underwent no reaction with either trimethylarsine or trimethylstibine, and trimethylstibine reacted anomalously with diborane and boron trifluoride. In general, the relative order of adduct bond strengths as determined by gas-phase calorimetry2 is supported by the results of these experiments. Under the conditions of these experiments, no evidence was found for salt formation or for ligand exchange in the adducts.

A number of imidazole derivatives were prepared in the course of studying the limits of carbon‐metal bond formation in complexes of imidazole with first‐row transition metals. Seven of the compounds were new. The 4‐ and 5‐methyl and 4,5‐dimethyl derivatives of l‐(2‐pyridyl)‐imidazole were prepared by reaction of the appropriate imidazole with 2‐bromopyridine. Alkylation of imidazole, 4,5‐dimethylimidazole, and benzimidazole with 2‐chloromethylpyridine gave a series of 1‐(2‐pyridylmethyl)imidazoles. 1‐(2,3‐Diaminopropyl)imidazole was prepared in six steps via a Gabriel sequence.

A class of nonionic surfactants has been observed to function as associative thickeners, dispersants, and wetting agents in aqueous flowable pesticide formulations at use levels of 1 to 3%. This phenomenon provides an alternative to conventional thickeners such as gums and minerals. These surfactant/thickeners require a finely ground substrate, such as a pesticide active ingredient for rheology modification. Combinations of these surfactants with other nonionic and anionic surfactants permit the formulator to control the rheology or suspensibility, or both, in a wide range of water hardnesses. This phenomenon has been demonstrated with several pesticide active ingredients including atrazine, linuron, chloroneb, and carbaryl. The viscosity, viscous yield, suspensibility foaming behavior, and product stability of several prototype atrazine formulations are described.