Are there heptaboranes

Hydroxo-bridge cleavage in dicobalt(III) complexes

“…It is possible from the appearance of Figure 2 in the DeMaine and Hunt paper that the third term with an [H+]2 dependence in the numerator may be effective over the range [H+] = 0.5 to 1.0 M. We also note that El-Awady and Hugus1 in their study of I require an |H+]2 dependent term in the rate law. Data obtained by Rasmussen and Bjerrum12 for acid cleavage of I at [H+] < 0.05 M fit a dependence of the form (1), which is again consistent with (7) providing (ki + k-i) » kz[H+], Hoffmann and Taube3 have studied the hydroxo bridge cleavage of the complex (NH3)4-Co^(OH,OH)-Co(NH3)44+, and for the range of [H+] investigated find their data give an adequate fit to a rate law of the form a[H+]/(l + Z>[H+]). Also Lee Hin-Fat and Higginson18 have reported data for the hydroxo-bridge cleavage of ( 2 4)2<2 •µ( , ) -Co-(C204)24-at pH 3.5-4.5, and find a first-order [H+] dependence.…”

“…The study by DeMaine and Hunt2 on I includes data at pH's 2.2-4.0, and identification of a term ko which is independent of [H+], No attempt was made to explain this term. According to the mechanism (3)-( 6) the behavior could be adequately represented by the first term in (7) with (ki + k-i) » k%[H+}. For this condition kz, kit and k-i are the only effective paths.…”

The Wade–Mingos rules in seven-vertex dimetallaborane chemistry: Hydrogen-rich Cp2M2B5H9 systems of the second and third row transition metals

“…Unlike the well-known nido boranes B 5 H 9 and B 6 H 10 , no B 7 H 11 nido heptaboranes have been synthesized as stable compounds [41,42]. Normally n-vertex nido borane polyhedra are obtained by removal of the highest degree vertex from the closo n þ 1 polyhedron.…”