Synthesis and an ab initio/IGLO/NMR study of 7-vertex nido-phosphacarboranes: nido-6-R'-3,4-R2-6,3,4-PC2B4H4

Keller, W.; Barnum, Beverly A.; Bausch, Joseph W.; Sneddon, Larry G.

doi:10.1021/ic00075a019

Cited by 23 publications

(45 citation statements)

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“…The structures of anions 1 - and 2a - are also confirmed by ab initio/IGLO/NMR calculations . In these calculations, the geometry of the proposed structure is first optimized using ab initio theory.…”

Section: Resultsmentioning

confidence: 78%

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New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C₂B₈H₁₁^- and nido-B₁₀H₁₃^-

Wille

Carroll

et al. 1996

J. Am. Chem. Soc.

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A synthetic sequence involving the initial nucleophilic attack of the isoelectronic nido-5,6-C2B8H11 - or nido-B10H13 - anions at a nitrile carbon, followed by nitrile hydroboration and cage-insertion, has been found to yield new azacarborane clusters in good yields. Thus, the reaction of nido-5,6-C2B8H11 - with refluxing acetonitrile gave the azatricarbaborane anion arachno-7-CH3-5,7,14,12-C3NB8H11 - (1 - ) in 65% yield, while nido-B10H13 - reacted with acetonitrile, benzyl cyanide, or CH3 13CN to give the azamonocarbaborane anions arachno-7-CH3-7,12-CNB10H13 - (2a - ), arachno-7-Bn-7,12-CNB10H13 - (2b - ), and arachno-7-CH3-7,12-13CNB10H13 - (2a - -13C), respectively. Single-crystal X-ray studies of the isoelectronic clusters, 1 - and 2a - , showed that hydroboration of the nitrile occurred, with the resulting imino group inserting into the cage framework in a position bridging the B2 and B11 borons. Consistent with their arachno skeletal electron counts, 1 - and 2a - have cage frameworks containing two six-membered open faces that may be derived from a bicapped hexagonal antiprism by removal of two non-adjacent five-coordinate vertices. Alternatively, 1 - and 2a - may be considered as having 10-vertex arachno frameworks with exopolyhedral bridging imine substituents. Acidification of 1 - resulted in loss of one boron and the imine nitrogen and formation of the known tricarbaborane nido-6-CH3-5,6,9-C3B7H10. In contrast, acidification of 2 - led to loss of only one boron to yield the new azamonocarbaborane hypho-12-R-12,13-CNB9H15 (3). A single-crystal X-ray study confirmed that 3 has an 11-vertex hypho structure, containing two six-membered open faces, that is based on a 14-vertex closo polyhedron missing three vertices. In 3, further hydroboration of the CN group occurred, such that the carbon contains an additional hydrogen and the nitrogen is connected to two borons. Deprotonation of 3 with Proton Sponge, 1,8-bis(dimethylamino)naphthalene, initially yielded hypho-12-R-12,13-CNB9H14 - (3 - ), which subsequently underwent a skeletal rearrangement to yield the isomeric anion hypho-12-R-12,11-CNB9H14 - (4 - ). A single-crystal X-ray study of 4 - confirmed that it has an 11-vertex hypho structure with one seven-membered and one five-membered open face. Subsequent acidification of 4 - resulted in loss of one additional boron to give hypho-8-R-8,13-CNB8H14 (5). Deprotonation with Proton Sponge gave the new anion hypho-8-R-8,13-CNB8H13 - (5 - ). Based upon spectral and computational data, 5 and 5 - are proposed to have the CN unit incorporated into a 10-vertex hypho structure.

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Section: Resultsmentioning

confidence: 78%

“…Computational Methods. The combined ab initio/IGLO/NMR method, using the GAUSSIAN90 and GAUSSIAN92 programs, was used as described previously . The geometries were fully optimized at the HF/6-31G* level within the specified symmetry constraints (using the standard basis sets included) on a Silicon Graphics International IRIS 4D/440VGX computer.…”

Section: Methodsmentioning

confidence: 99%

New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C₂B₈H₁₁^- and nido-B₁₀H₁₃^-

Wille

Carroll

et al. 1996

J. Am. Chem. Soc.

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“…Even though there is a mention in the literature of the isolation of a mixture that contains nido ‐Ph 2 Et 2 P 2 C 2 B 4 H 4 as one of the components,21 the compounds described in this work are first parent representatives of the diphosphadicarbaborane series isolated in a pure state and their synthesis further demonstrates the viability of the PCl 3 ‐mediated insertion reactions into borane clusters 1. A very interesting aspect of the reactions described is the explicit trend for the incorporation of a maximum number of the P vertices under the formation of very stable eleven‐vertex nido ‐phosphacarborane cages.…”

Section: Discussionmentioning

confidence: 92%

Phosphacarborane Chemistry: The 7,8,9,11-, 7,9,8,10- and 7,8,9,10-Isomers ofnido-P2C2B7H9—Diphosphadicarbaborane Analogues of 7,8,9,10-C4B7H11

et al. 2001

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The reaction between the carborane arachno-4,6-C2B7H13 (1) and PCl3 in dichloromethane in the presence of a "proton sponge" (PS = 1,8-dimethylaminonaphthalene) resulted in the isolation of the eleven-vertex nido-diphosphadicarbaboranes 7,8,9,11-P2C2B7H, (2) and 3-Cl-7,8,11-P2C2B7H, (3-Cl-2) in yields of 54 and 7%, respectively. Replacement of the PS by NEt3 in the same reaction gave diphosphadicarbaboranes 2 and 3-CI-2 together with the isomeric species nido-7,9,8,10-P2C2B7H, (3) in yields of 28, 15 and 3%, respectively. The reaction between the isomeric carborane arachno-4,5-C2B7H13 (4) and PCl3 in dichloromethane in the presence of PS gave the asymmetrical isomer, nido-7,8,9,10-P2C2B7H, (5). along with the chloro derivatives 4-Cl-7,8,9,10-P2C2B7H8 (4-Cl-5) and 11-Cl-7,8,9,10-PC2B7,H8 (11-Cl-5) (yields of 21, 1 and 13%, respectively). The structures of the chlorinated derivatives 3-Cl2 and 11 -Cl-5 were determined by X-ray diffraction analysis. In addition, the structures of all compounds isolated were geometry-optimised and confirmed by comparison of experimental 11B chemical shifts with those calculated by the GIAO-SCF/II//RMP2(fc)/6-31G* method. The calculations also include the structure and 11B NMR shifts of the isomer nido-7,10,8,9-P2C2B7H9 (6) which has not yet been isolated.

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“…The observation that the 31 P NMR resonance of the capping phosphorus at δ −129.7 ppm was shifted upfield by about 283 ppm from its precursor, [2,4,6-( t -C 4 H 9 ) 3 C 6 H 2 ]PCl 2 , was taken as further evidence of π-type complex. On the other hand, Sneddon and co-workers found very different results from the reaction of NaLi[2,3-(R) 2 -2,3-C 2 B 4 H 4 ] (R = Et, Bz) and R‘PCl 2 (R‘ = Ph, t -Bu, Me) . The 11 B NMR spectra, combined with an ab initio /IGLO/NMR study indicated that the resulting phosphacarboranes were 7-vetex cages, best formulated as nido -6-R‘-3,4-(R) 2 -6,3,4-PC 2 B 4 H 4 .…”

Section: E Complexes Of Group 15 Elementsmentioning

confidence: 99%

“…Under certain conditions these lone pairs can be made to react with R + moieties to give the electronically equivalent RE + units, as found in the reaction of nido -PCB 9 H 11 - with MeI to give nido -P(Me)CB 9 H 11 . However, there seems to be no clear consistent picture of the interaction of a “neutral” RE unit with carborane cages; in some cases they seem to act as two-electron donors, , while in others a four-electron donor model seems to be more useful …”

Section: E Complexes Of Group 15 Elementsmentioning

confidence: 99%

Recent Advances in the Chemistry of Heterocarborane Complexes Incorporating s- and p-Block Elements

1997

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Synthesis and an ab initio/IGLO/NMR study of 7-vertex nido-phosphacarboranes: nido-6-R'-3,4-R2-6,3,4-PC2B4H4

Cited by 23 publications

References 1 publication

New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C₂B₈H₁₁^- and nido-B₁₀H₁₃^-

New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C₂B₈H₁₁^- and nido-B₁₀H₁₃^-

Phosphacarborane Chemistry: The 7,8,9,11-, 7,9,8,10- and 7,8,9,10-Isomers ofnido-P2C2B7H9—Diphosphadicarbaborane Analogues of 7,8,9,10-C4B7H11

Recent Advances in the Chemistry of Heterocarborane Complexes Incorporating s- and p-Block Elements

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Synthesis and an ab initio/IGLO/NMR study of 7-vertex nido-phosphacarboranes: nido-6-R'-3,4-R2-6,3,4-PC2B4H4

Cited by 23 publications

References 1 publication

New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C2B8H11- and nido-B10H13-

New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C2B8H11- and nido-B10H13-

Phosphacarborane Chemistry: The 7,8,9,11-, 7,9,8,10- and 7,8,9,10-Isomers ofnido-P2C2B7H9—Diphosphadicarbaborane Analogues of 7,8,9,10-C4B7H11

Recent Advances in the Chemistry of Heterocarborane Complexes Incorporating s- and p-Block Elements

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New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C₂B₈H₁₁^- and nido-B₁₀H₁₃^-

New Synthetic Routes to Azacarborane Clusters: Nitrile Insertion Reactions of nido-5,6-C₂B₈H₁₁^- and nido-B₁₀H₁₃^-