Synthesis of closo-1-methylphosphadodecaborane(12), B11H11PCH3 and nido-7-methylphosphaundecaborane(13), B10H12PCH3, from the [B11H13]2- anion and their molecular structures
“…The 11 B NMR for compounds 4a and 4b would, therefore, be expected to exhibit the observed four resonances in a 1:4:2:3 ratio, as reported for the closely related cluster 9 . The chemical shifts and distributions of peak intensities observed for the resonances of 4a and 4b are also very similar to those found for the other known nido -EB 10 heteroboranes, with the resonance of intensity 1 at lowest field strength and the resonance of intensity 3 at highest field strength. 3 Structures of nido -RPB 10 H 12 ( 7 ; R = CH 3 , C 2 H 5 ), nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )PB 10 H 12 ( 8 ), and nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )AsB 10 H 12 ( 9 ) 33 (terminal cage hydrogen atoms have been omitted for clarity). 4 Numbering scheme for compounds 4a and 4b .…”
Section: Resultssupporting
confidence: 67%
“…A number of heteroborane clusters are known which display structures similarly based upon the nido -EB 10 framework. These closely related compounds include nido -RPB 10 H 12 ( 7 , where R = CH 3 , C 2 H 5 ), nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )PB 10 H 12 ( 8 ), and nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )AsB 10 H 12 ( 9 ), as shown in Figure . As described previously, compounds 4a and 4b show four 11 B NMR resonances in a 1:4:2:3 ratio.…”
Section: Resultsmentioning
confidence: 99%
“…In the work reported here, we describe the reactions of several phosphaalkynes with nido -decaborane(14) in the preparation of inserted phosphaborane clusters in good yield. The reaction of a phosphaalkyne with the large nido -decarborane(14) cluster was initially investigated, since the larger polyhedral phosphaboranes are usually quite stable and are, therefore, often easier to purify and characterize relative to the smaller cage systems. − …”
The room-temperature reaction of equimolar quantities of phosphaalkyne RCtP (2a; R ) t Bu; 2b, R ) adamantyl) with the decaborane(12)-Lewis base adduct B 10 H 12 ‚2CH 3 CN (3) resulted in the formation of new phosphaborane compounds (phosphine-methylene ylides), nido-RC(H)PB 10 H 13 (4a, R ) t Bu; 4b, R ) adamantyl), in good yield (approximately 50% each). These slightly air-sensitive compounds were fully characterized by 1 H, 11 B, 13 C, and 31 P NMR, 2D 11 B-11 B COSY NMR, FT-IR, and mass spectroscopic analyses. The structures of 4a and 4b are proposed to consist of a nido-PB 10 framework formally based upon a 26skeletal-electron nido-[B 11 H 11 ] -parent compound. Only the phosphorus atom was observed to be incorporated into the polyhedral framework with an exopolyhedral C(H)R group doubly bound to the cage phosphorus atom. Two related mechanisms are proposed to account for the observed products from these reactions.
“…The 11 B NMR for compounds 4a and 4b would, therefore, be expected to exhibit the observed four resonances in a 1:4:2:3 ratio, as reported for the closely related cluster 9 . The chemical shifts and distributions of peak intensities observed for the resonances of 4a and 4b are also very similar to those found for the other known nido -EB 10 heteroboranes, with the resonance of intensity 1 at lowest field strength and the resonance of intensity 3 at highest field strength. 3 Structures of nido -RPB 10 H 12 ( 7 ; R = CH 3 , C 2 H 5 ), nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )PB 10 H 12 ( 8 ), and nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )AsB 10 H 12 ( 9 ) 33 (terminal cage hydrogen atoms have been omitted for clarity). 4 Numbering scheme for compounds 4a and 4b .…”
Section: Resultssupporting
confidence: 67%
“…A number of heteroborane clusters are known which display structures similarly based upon the nido -EB 10 framework. These closely related compounds include nido -RPB 10 H 12 ( 7 , where R = CH 3 , C 2 H 5 ), nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )PB 10 H 12 ( 8 ), and nido -(Fe(η 5 -C 5 H 5 )(CO) 2 )AsB 10 H 12 ( 9 ), as shown in Figure . As described previously, compounds 4a and 4b show four 11 B NMR resonances in a 1:4:2:3 ratio.…”
Section: Resultsmentioning
confidence: 99%
“…In the work reported here, we describe the reactions of several phosphaalkynes with nido -decaborane(14) in the preparation of inserted phosphaborane clusters in good yield. The reaction of a phosphaalkyne with the large nido -decarborane(14) cluster was initially investigated, since the larger polyhedral phosphaboranes are usually quite stable and are, therefore, often easier to purify and characterize relative to the smaller cage systems. − …”
The room-temperature reaction of equimolar quantities of phosphaalkyne RCtP (2a; R ) t Bu; 2b, R ) adamantyl) with the decaborane(12)-Lewis base adduct B 10 H 12 ‚2CH 3 CN (3) resulted in the formation of new phosphaborane compounds (phosphine-methylene ylides), nido-RC(H)PB 10 H 13 (4a, R ) t Bu; 4b, R ) adamantyl), in good yield (approximately 50% each). These slightly air-sensitive compounds were fully characterized by 1 H, 11 B, 13 C, and 31 P NMR, 2D 11 B-11 B COSY NMR, FT-IR, and mass spectroscopic analyses. The structures of 4a and 4b are proposed to consist of a nido-PB 10 framework formally based upon a 26skeletal-electron nido-[B 11 H 11 ] -parent compound. Only the phosphorus atom was observed to be incorporated into the polyhedral framework with an exopolyhedral C(H)R group doubly bound to the cage phosphorus atom. Two related mechanisms are proposed to account for the observed products from these reactions.
“…Recently, closo -boranes with only one heteroatom, e.g., B 11 H 11 NH, B 11 H 11 PR, B 11 H 11 S, B 9 H 9 NH, and B 9 H 9 S, in 10 and 12 vertex systems have been synthesized. Unlike closo -C 2 B n - 2 H n ( n = 5−12), the monoanionic analogues, CB n - 1 H n - ( n = 5−12), have received less attention, ,− ,− even though the first member of this family, CB 11 H 12 - , was prepared by Knoth 30 years 42a…”
Comprehensive ab initio calculations RMP2(fc)/6-31G on the closo-monocarbaboranes, CB(n)()(-)(1)H(n)()(-) (n = 5-12), and the closo-dicarboranes, C(2)B(n)()(-)(2)H(n)() (n = 5-12), show that the relative energies of all the positional isomers agree with the qualitative connectivity considerations of Williams and with the topological charge stabilization rule of Gimarc. The reaction energies (DeltaH) of the most stable positional isomers, 1-CB(4)H(5)(-), CB(5)H(6)(-), 2-CB(6)H(7)(-), 1-CB(7)H(8)(-), 5-CB(8)H(9)(-), 1-CB(9)H(10)(-), 2-CB(10)H(11)(-), CB(11)H(12)(-), as well as 1,5-C(2)B(3)H(5), 1,6-C(2)B(4)H(6), 2,4-C(2)B(5)H(7), 1,7-C(2)B(6)H(8), 4,5-C(2)B(7)H(9), 1,10-C(2)B(8)H(10), 2,3-C(2)B(9)H(11), and 1,12-C(2)B(10)H(12) (computed using the equations, CBH(2)(-) + (n - 1)BH(increment) --> CB(n)()H(n)()(+1)(-) (n = 4-11) and C(2)H(2) + nBH(increment) --> C(2)B(n)()H(n)()(+2) (n = 3-10)), show that the stabilities of closo-CB(n)()(-)(1)H(n)()(-) and of closo-C(2)B(n)()(-)(2)H(n)() generally increase with increasing cluster size from 5 to 12 vertexes. This is a characteristic of three-dimensional aromaticity. There are variations in stabilities of individual closo-CB(n)()(-)(1)H(n)()(-) and closo-C(2)B(n)()(-)(2)H(n)() species, but these show quite similar trends. Moreover, there is rough additivity for each carbon replacement. The rather large nucleus independent chemical shifts (NICS) and the magnetic susceptibilities (chi), which correspond well with one another, also show all closo-CB(n)()(-)(1)H(n)()(-) and closo-C(2)B(n)()(-)(2)H(n)() species to exhibit "three-dimensional aromaticity". However, the aromaticity ordering based on these magnetic properties does not always agree with the relative stabilities of positional isomers of the same cluster, when other effects such as connectivity and charge considerations are important.
“…High purity deuterated diborane is receiving very favorable attention for applications in plasma fusion reactors. We also developed a number of practical syntheses of higher boranes, b- 8 including BloH 14 , using BH 9 as a feed stock, thus enabling the conversion of surplus B 5 H 9 in U.S. Government stockpiles (ca. 200,000 lbs) to more useful materials.…”
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ABSTRACT (Maximum 200 words)The synthesis of B 1 0 H 14 from B 5 H 9 was modified to facilitate large scale production. Reductions of boranes by alkali and lanthanide metals were studied.
Depending upon reaction conditions chosen, the anions
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