Preparation of lithium nonahydrotetraborate

Abstract

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.

Stabilization of small-ring acetylenes by complex formation with platinum

“…Treatment of 1 with CF3C02H in benzene at room temperature gives the -cycloheptenyl complex -€7 -Pt(OCOCF3)(PPh3)2 (3): mp 178-180°; ir (KBr disk) 1600 cm'1 *[f(C=C) as shoulder on y(C=0)]; nmr (CDC1,) 5.02 (t, 1, /h-h = 6 Hz, /Pt_H = 67 Hz, C=CH), 1.8-0.3 (broad multiples, 10, CM). The -cyclohexenyl complex £r-CeH9Pt(OCOCF3)(PPh3)2 (4) is similarly obtained from 2: mp 190-192°d ec; ir (KBr disk) 1610 cm-1 [P(C=C)]; nmr (CDC13) 4.92 (broad t, 1, C=CH), 1.36 (4), 0.76 (2), 0.46 (2) (broad multiplets, CM).…”

Evaluating the Role of Triborane(7) As Catalyst in the Pyrolysis of Tetraborane(10)

“…The large barrier indicates that the free radical mechanism will not contribute to H 2 production at 373 K. However, if the B 4 H 10 reaction mixture contained an impurity with a smaller barrier for H atom formation, the barrier for H 2 formation through the free radical mechanism might be competitive. Such a situation could explain the 3/2 order rate law reported by Bond and Pinsky for the pyrolysis for B 4 H 10 .…”

“…It has been assumed that the pyrolysis of B 4 H 10 is initialized by the elimination of hydrogen since the reaction is known to be first order in B 4 H 10 concentration. A counterexample is from a study by Bond and Pinsky who found that the reaction was 3/2 order in B 4 H 10 . However, the reliability of their experiment observations has been questioned by Greenwood. , …”

“…As the second smallest stable boron hydride, B 4 H 10 [tetraborane(10)], also plays an important role in thermal reactions of boron hydrides . There is still doubt concerning the mechanism and even the initial order of the reaction. − …”