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The chloro(dimethylamido)phosphorus(III) ligands interact with AlC13 under appropriate conditions to give (CH3)2N-PC12.AICI3, ((CH3)2N)2PCl.AlC13, and [2((CH3)2N)2PCI].AlC13. Tris(dimethylamido)phosphorus(III) and AIC13 react under comparable conditions to give ((CH&N)3P*AlCI3. The tris ligand will also react with ((CH3)2N)2PCI*AlCI3 to give ((CH3)2N)3P.((CH3)2N)2PCl.AICl3 but it will not react with ((CH3)2N)jP-AlCI3 to give [2((CH3)2N)3P].AIC13. Trimethylamine will gradually replace some of the phosphorus ligand from the complex to give some (CH3)3N*AlC13. A solution of dichloro(dimethylamido)phosphorus(III) ligand in isopropyl ether was stable as was a solution of aluminum chloride in isopropyl ether. On the other hand, an isopropyl ether solution containing A1C13 and the dichloro(dimethylamido)phosphorus(III) ligand gave 1 mol of isopropyl chloride for each mole of PC13 and each mole of the dichloro(dimethy1amido)phosphorus ligand. The ether solution turned red as a result of the formation of an aluminum chloride-olefin complex. The splitting process to generate alkyl halide was not observed with diethyl ether. The chloride transferred came from the phosphorus ligand, not the AlC13. The ligand ((CH3)2N)zPCI will displace about 70% of the diisopropyl ether from the diisopropyl etherate of AIC13 and ((CH3)2N)3P will displace 1OC% of the ether. Models to interpret these facts are presented. Registry No. ((CH3)2N)2PCbAIC13, 60607-14-9; (CH3)zNP-C12.AIC13, 60594-92-5; [2((CH3)2N)2PCl].AlC13, 60594-85-6; ((CH3)2N)2PCl-((CH3)2N)3P-AlC13,60594-83-4; ((CH3)2N)3P*AlC13,

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M an ga nese and R hen i u m D i hydro b is ( pyrazo I y I ato ) borateco m pl exes

The question must now be answered as to why the observed kinetic behavior is markedly different in CCU-DMSO compared to CHCI3-DMSO. Obviously the difference must be due to the relative hydrogen bonding capabilities of chloroform and carbon tetrachloride. Chloroform is known to form weak hydrogen bonds;3 e.g., the association constant between DMSO and chloroform in carbon tetrachloride has been estimated to be 31 M-1.17 This accounts for the lower stability of the dimer in chloroform relative to carbon tetrachloride. The differences in kinetic behavior in CCl4-DMSO and CHCI3-DMSO, imply that the breakdown and formation of a DMSO-2-pyridone hydrogen bond in the dimer is more rapid in chloroform than in carbon tetrachloride. This is probably due to the fact that this step is facilitated (17) P.

increased stability of the parent ion on increased methyl substitution could be attributed to the ability of the methyl group to release election density into the borazine ring thus stabilizing the parent ion.The general substituent effects on the relative stability of the parent ion observed for the B-substituted vV-trimethylborazines also obtains for the B-substituted borazines. Mass spectral data available in the literature were analyzed by the method described here and the results summarized in Table X. The stability of the parent ion of B-monosubstituted borazines increases in the order F < Cl < OCH3 < CH3 < Br; for the known B-disubstitüted derivatives the same order is observed. The results in both series of compounds are in general agreement with the data obtained for the corresponding N-trimethylborazine derivatives. A comparison of the results in Tables IV and VIII indicates that the loss of a hydrogen atom from an //-methyl group is more facile than from a B-methyl group, which is in agreement with the more ready formation of an immonium ion (II).

The decomposition of tetraborane(lO) has been studied at 40,50, and 60°and at pressures of 37,73, and 110 Torr at each of these temperatures. The course of the reaction was followed by the periodic analysis of the mixture for tetraborane(lO), diborane, pentaborane(9), and pentaborane(ll). The reaction is 3/2 order in tetraborane(10) at each temperature and pressure except for the 60°runs at the two lower pressures. In these cases the decomposition appears to be approaching first-order behavior.xcellent bibliographies of the thermal decomposition of various boron hydrides may be found in several books.1-5 The studies dealing primarily with the decompositions of tetraborane(lO) are those of