Transformation of various multicenter bondings within bicapped-square antiprismatic motifs: Z-rearrangement

Abstract

Reported herein are mutual rearrangements in the whole series of seven bicapped-square antiprismatic closo-C2B8H10 by means of high-quality computations that disprove the earlier postulated dsd (diamond-square-diamond) scheme for these isomerizations....

Access to cationic polyhedral carboranes via dynamic cage surgery with N-heterocyclic carbenes

“…This fact is further demonstrated by the 11 In the case of p-2, the alternating but symmetrical positions of the carbon atoms inside the cluster predetermine the averaging of the respective separations, such as 1.604(7) and 1.622(6) Å for the B-carbene ones. In fact, these structures evoke the structure suggested for the transition state of the isomerisation of ten-vertex clusters by Z-mechanism 43 .…”

DFT Surface Infers Ten-Vertex Cationic Carboranes from the Corresponding Neutral closo Ten-Vertex Family: The Computed Background Confirming Their Experimental Availability

“…[14]) via two transition states and one intermediate 1, in which the opening of the square antiprismatic cage is marked: see Figure 1. The position of the C-C vector in o-2 is consistent with that observed in the transition state of the isomerization of closo-1,2-C 2 B 8 H 10 to itself due to Z-isomerization, with the latter being experimentally observed in the R-substituted derivatives of closo-1,2-C 2 B 8 H 10 [16]. 1 and S1 and the Section 3 for details).…”

“…[14]) via two transition states and one intermediate 1, in which the op the square antiprismatic cage is marked: see Figure 1. The position of the C-C v o-2 is consistent with that observed in the transition state of the isomerizatio so-1,2-C2B8H10 to itself due to Z-isomerization, with the latter being experimen served in the R-substituted derivatives of closo-1,2-C2B8H10 [16]. The reaction starts with the attack of a lone electron pair of a NHC on one of the most positive boron atom pairs within the cage, i.e., on B(3) [10][11][12], and following this proceeds very smoothly; o-2, conforming to the decaborane shape, is afforded (in line with Ref.…”

“…However, when three isomers of closo-1,N-C 2 B 8 H 10 (N = 2,6,10) were allowed to react with N-heterocyclic carbenes (NHCs, Scheme 1), the cationic arrangements of decaborane shapes were obtained by HCl acidification of the neutral species of the decaborane shapes [14]. Note that such shapes were already spotted when these closo structural motifs originated by click chemistry [15], also including the aforementioned Z-rearrangement [16]. The existence of cationic ten-vertex carboranes, which retain the bicapped square antiprismatic arrangement only in the case of closo-1,10-C 2 B 8 H 10 , prompted us to search the corresponding reaction pathways of their formation computationally by employing modern computational protocols.…”

Silylium ion-mediated cage-opening functionalization of closo-B10H102− salts

“…In the 1960s, Hoffmann, Lipscomb, Mutterties, et al extensively studied the intramolecular polyhedral rearrangement of closo -B 10 H 10 2− , in which new closo -B 10 H 10 2− derivatives were obtained and a high temperature was usually needed. 2 Instead of the above processes, Marshall's group found that (NH 4 ) 2 B 10 H 10 reacted smoothly with anhydrous HCl in diethyl sulfide at room temperature, affording the cage-opening product nido -B 10 H 12 (Et 2 S) 2 in about 92% yield (Scheme 1a). 3 This discovery paved the way for proton-mediated cage-opening functionalization (arylation, alkylation, hydroxylation, and halogenation) of closo -B 10 H 10 2− salts to make other useful boron-clusters, especially considering the ready availability of these salts.…”