A new nido-5-vertex cluster, phosphacarba-nido-pentaborane, 2-tBu-1,2-PCB3H5Electronic supplementary information (ESI) available: rotatable 3-D molecular structure diagrams of MP2-optimised geometries for 2-tBu-1,2-PCB3H5 2, 1-tBu-2,1-PCB3H5 and P4 in CHIME format. See http://www.rsc.org/suppdata/cc/b2/b204409a/

Abstract

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 gas-phase reactions of tetraborane(10), B4H10, with substituted alkynes: new nido-dicarbapentaboranes and arachno-monocarbapentaboranes

“…15 Mass and proton NMR spectra of the products from the quenched reaction of B 4 H 10 with the partially deuterated propyne MeCCD showed that all these volatile carbaboranes retain a C-D bond. The proton spectrum of deuterated 3a was consistent 20 with a 1 : 1 mixture of 2,5--exo-DCH-and 2,5--endo-DCH-1-Me-1-CB 4 H 7 .…”

“…This product was identified by NMR spectroscopy as 1-Me 3 Si-1,2-C 2 B 3 H 6 for which the B(4) peak value differs little from that of the parent carbaborane, 1,2-C 2 B 3 H 7 ; thus no 'trans' effect 27 is observed. The other possible 20 isomer, 2-Me 3 Si-1,2-C 2 B 3 H 6 , was not present in the fractions collected. 42 Minor basket products were also present in which a second ethene molecule appears to have been hydroborated by B 4 H 10 to form an alkyl group -RCHCH 2 R, since the basket compound formed initially does not give such 45 products with ethenes.…”

“…25,26,27 A second fraction from the quenched reaction of MeCCH and B 4 H 10 , with a mass cut-off of 90, was identified, by comparison of the NMR data with literature values, as the known 28 2-Me-2,3-C 2 B 4 H 7 3a . The Me-C-C-H link in propyne is retained in the formation of these nido- 20 carbaboranes.…”

“…1 A widely-used 20 synthesis involves the treatment of decaborane (14), B 10 H 14 , with a substituted alkyne RC≡CR in the presence of Lewis base to form the closo-carbaborane 1-R-2-R-1,2(ortho)-C 2 B 10 H 10 . 2 A less common route, in which pentaborane (9), B 5 H 9 , is used in place of B 10 H 14 generally affords the carbaborane nido 2-R-3-R- 25 2,3-C 2 B 4 H 6 .…”

Selective Preparation of the [3,5‐tBu2‐1,2,4‐C2P3]− Ion and Synthesis and Structure of the Cationic Species nido‐[3,5‐tBu2‐1,2,4‐C2P3]+, Isoelectronic with [C5R5]+

“…The value for the apical phosphorus atom is in good agreement with that found for nido-2-tBu-1,2-PCB 3 H 5 . [17] The lack of signals at these chemical shifts in our spectra led us to conclude that a fluxional process was occurring, the result of which was to exchange the apical and basal phosphorus atoms. A similar process was predicted by Stohrer and Hoffmann [16] in their analysis of bond-stretch isomerism and polytopal rearrangements within the [C 5 H 5 ] + manifold.…”