“…A classic route into carbaborane chemistry involves the insertion of the two unsaturated carbon atoms of an alkyne into a boron cluster. For example tetraborane, B 4 H 10 , reacts with ethyne to yield 1,2-C 2 B 3 H 7 , 6 the only heteroborane with a nido-5-vertex geometry reported prior to the work reported here. 7 B 4 H 10 + HC…”
The gas-phase reaction of the phosphaalkyne P identical to CtBu with tetraborane(10), B4H10, yields the nido five-vertex phosphacarbaborane cluster compound 2-tBu-1,2-PCB3H5 2 with an unusual 31P NMR peak shift of -500.5 ppm.
“…A classic route into carbaborane chemistry involves the insertion of the two unsaturated carbon atoms of an alkyne into a boron cluster. For example tetraborane, B 4 H 10 , reacts with ethyne to yield 1,2-C 2 B 3 H 7 , 6 the only heteroborane with a nido-5-vertex geometry reported prior to the work reported here. 7 B 4 H 10 + HC…”
The gas-phase reaction of the phosphaalkyne P identical to CtBu with tetraborane(10), B4H10, yields the nido five-vertex phosphacarbaborane cluster compound 2-tBu-1,2-PCB3H5 2 with an unusual 31P NMR peak shift of -500.5 ppm.
“…Quenched reaction 10,13,19 25-70 o C, 20-60 min B 4 H 10 + HC≡CH → nido-1,2-C 2 B 3 H 7 (25%) 50 Grimes, Bramlett and Vance 7,9 and the Leeds group 16,17,18 have also investigated the flash and completed gas-phase reactions of B 4 H 10 with propyne and 2-butyne under similar reaction conditions (see reactions 4 and 5 below), and Grimes and Ledoux have explored the completed gas-phase reaction of B 4 H 10 55 with trimethylsilylethyne -no volatile carbaborane product was obtained from this latter reaction. 14 …”
Section: )mentioning
confidence: 99%
“…4,5 Not long after these carbaboranes were first discovered, some 40 30 years ago, Grimes and co-workers reported a series of complex reactions of tetraborane (10), B 4 H 10 , with alkynes. [6][7][8][9][10][11][12][13][14][15] Many new carbaboranes were discovered from the gas-phase reactions of B 4 H 10 with ethyne HC≡CH. These reactions have also been explored more recently in Leeds.…”
Section: Introductionmentioning
confidence: 99%
“…These reactions have also been explored more recently in Leeds. [16][17][18][19] The reactions were of three 35 types, and the major carbaborane product in each case is shown below: 1) High-energy ('Flash') reaction 6,7,16,17 100 o C, 'Flash' 40 B 4 H 10 + HC≡CH → closo-2,4-C 2 B 5 H 7 (<1% yield) 2) Completed reaction 6,[8][9][10][11][12][13][14][15][16][17][18][19] 25-70 o C, 3 days B 4 H 10 + HC≡CH → nido-2,4-Me 2 -2,3-C 2 B 4 H 6 (7%) 45 …”
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“…In a series of papers published between 1966 and 1972, Grimes and co-workers reported the results of investigations into the complex gas-phase reactions between tetraborane(10) and various alkynes at temperatures in the range 25−70 °C. − The reaction between B 4 H 10 and ethyne at 25−50 °C was reported to yield many volatile nido -carboranes, including 1,2-C 2 B 3 H 7 ( 1 ), 2,3-C 2 B 4 H 8 ( 2a ), 2-Me-2,3,4-C 3 B 3 H 6 ( 3a ), 2,3-Me 2 -2,3,4-C 3 B 3 H 5 ( 3b ), 2,4-Me 2 -2,3,4-C 3 B 3 H 5 ( 3c ), and 4-Me-2-CB 5 H 8 ( 4a ) (see Figure ). 1 Range of volatile products from the reaction of B 4 H 10 and HC⋮CH, including views of 1,2-C 2 B 3 H 7 in the optimum refinement of the electron-diffraction data; (a) perspective view and (b) perpendicular to the molecular C s plane.…”
The molecular structure of nido-1,2-C(2)B(3)H(7), 1, the principal volatile carborane generated in the quenched gas-phase reaction of B(4)H(10) and ethyne at 70 degrees C, has been determined by a combined analysis of gas-phase electron-diffraction data and rotation constants restrained by ab initio computations at the CCSD(T)/TZP' level. The structure is consistent with a geometry having C(s)() symmetry, similar to that of pentaborane(9). The apical position is occupied by a carbon atom, displaced toward B(4) from a position directly above the B(5).B(3) vector, and hydrogen atoms asymmetrically bridge the B-B bonds. The basal atoms are almost coplanar, C(2) lying ca. 2 degrees below the B(3)-B(4)-B(5) plane. Important experimental structural parameters (r(alpha) degrees /pm, angle(alpha)/ degrees ) are r[C(1)-C(2)] = 162.6(6); r[C(1)-B(3)] = 161.4(3); r[C(2)-B(3)] = 154.3(2); r[C(1)-B(4)] = 157.4(5); r[B(3)-B(4)] = 185.7(3);
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