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NICKEL COMPLEXES 599 served for the future. It should be noted that the associations of Ag+ and CN-are the strongest which have been measured in molten salt soh-tions. Values of -AAl for associations of Ag+ with various ions in molten nitrates are in the order CN-It has been found that upon alteration of the R substituent in bis-( R-N-salicyla1dimine)-nickel( 11) complexes from methyl or n-alkyl to certain aryl groups, large increases in the solution paramagnetism in inert solvents are produced. The factors affecting this surprising behavior were investigated in an extensive study of the R = aryl complexes. By variation of substituents and their positions on the aryl portion of the molecules, it was found that the spectral and magnetic properties and the extent of molecular association could be consistently controlled. On the basis of this behavior the complexes fall into three categories: (1) those with o-substituted aryl groups, which are diamagnetic and monomeric; (2) those with phenyl and @-substituted aryl complexes, which are strongly paramagnetic in solution (peff > 2.8 B.M.), associated (1.5 < 8 < 2.0), and are either diamagnetic or paramagnetic solids; (3) those with m-substituted aryl groups, which have in solution paff 2 3.2 B.M., 2 < fi < 3, and are always paramagnetic solids. For complexes of the second category the magnetic and molecular weight data a t 37" were interpreted in terms of a diamagnetic monomer-paramagnetic dimer equilibrium. The results present further substantiation of the relation between solution paramagnetism and molecular association of apparently quadricoordinate Ni(I1) complexes. The nature of the associated forms in no case could be deduced with certainty from the data ; however, the presence of axially perturbed trans-planar coordination units appears likely.

The title reaction does not give the previously claimed benzoyldibutylborane. Instead, reduction of benzoyl chloride occurs, leading to benzyloxydibutylborane, some of which reacts further with benzoyl chloride to give benzyl benzoate. The characteristics reported for ' benzoyldibutylborane ' are matched by a mixture of these two compounds. The work also raises doubts about the nature of the reagent previously designated as ' Bu,BM '.IN 1952 Auten and Kraus prepared a reagent by the action of sodium-potassium alloy on dibutylchloroborane in diethyl ether [reaction (l)]. The exact nature of the reagent (i.e. the solution after removal of etherinsoluble material) was unknown (boron : alkali-metal ratio ca. 5 : 3), but the presence of nucleophilic BBu, units was said to be demonstrated by its reaction with iodomethane [reaction (2)], so the designation ' Bu,-BhI ' was adopted. Parsons and his co-workers carried out a similar reaction with CF31 in triethylamine [reaction (3)]. However, Koster and Benedikt could

Detailed investigations of reaction conditions for optimum formation of di-isopropylcarbamoyl-lithium from NNdi-isopropylformamide and organolithium reagents have led to the development of a nearly quantitative procedure, using t-butyl-lithium in diethyl ether-tetrahydrofuran-pentane (4 : 4 : 1 ) a t -95 "C. The species so formed reacts with electrophiles such as aldehydes, ketones, esters, and D, O to give high yields of the expected products. Less reactive electrophiles such as alkyl iodides also react, but yields are lower and these reactions are of little synthetic significance. Benzyl bromide is sufficiently reactive, but the initial product is acidic, so that deprotonation and further alkylation occur.

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