Polyhedral monocarbaborane chemistry. Routes to neutral, monoanionic and dianionic carbo-carbaborane rods

Synthesis and Characterization of 2‐Mono‐ and 1,2‐Diaminocarba‐closo‐dodecaborates M[1‐R‐2‐H2N‐closo‐CB11H10] (R=H, Ph, H2N, CyHN)

“…[55] A large number of other carborates with aryl substituents bonded to cluster atoms have been reported, for which analogous CÀC aryl [48,49,59,60] and BÀC aryl bond lengths [59] have been determined experimentally, for example in the [1-(4-MeC 6 H 4--4-C 6 H 4 )-12-(4-MeC 6 H 4 )-closo- (4) . [59] In contrast to the dA C H T U N G T R E N N U N G (C À Ph) distance in 2 and the dA C H T U N G T R E N N U N G (C À NH 2 ) and dA C H T U N G T R E N N U N G (B2ÀPh) distances in 5, the BÀNH 2 bond in anion 2 is much shorter than the sum of the covalent radii. The experimental and calculated bond lengths are 1.465(3) and 1.472 (Table 2), respectively, whereas from the covalent radii of boron and nitrogen a value of 1.55 [55] is calculated.…”

Ethynylmonocarba-closo-dodecaborates: M[12-HCC-closo-1-CB11H11] and M[7,12-(HCC)2-closo-1-CB11H10] (M=Cs+, [Et4N]+)

“…In contrast to substitution reactions at the carbon vertex of the {closo-1-CB 11 } cluster that are well developed, the selective introduction of a functional group that can be modified easily at one of the boron vertices is less studied [1]. A strategy for the functionalization at the antipodal boron atom and the upper belt boron atoms of the {closo-1-CB 11 } cluster is the partial iodination followed by exchange of the iodine substituent(s) against an alkyl [20], aryl [20][21][22] allyl [23,24], or alkynyl [25] group(s) by Pd-catalyzed cross-coupling reactions, that was first introduced into boron cluster chemistry for the related neutral dicarba-closo-dodecaboranes in the early 1980s [26][27][28].…”

Polyhedral monocarbaborane chemistry

“…17.5 to 19.7 Å (see Table 3). In contrast to other reported rod-like monocarbaborane derivatives, such as those based on the icosahedral {CB 11 } cluster [16], the species presented here have an inherent degree of angularity. In the cases of the closo compounds this angularity arises from the mutual ÔmetaÕ-type positionings of the C(1)-phenyl and B(6)-pyridyl(ene) groupings: the angles between the C(1)-C(11) and B(6)-N(61) bonding vectors for all the closo compounds 6, 8, 10, and 12 are given in Table 4.…”

“…The commercial availability of many pyridine derivatives that can be used as two-electron donors permits the ready synthesis of systematically related series of compounds. The resulting neutral species described, of which the molecules have an extended bent aspect, complement recently reported monoanionic and dianionic rod-like species that are also constructed from combinations of monocarbaborane and organic units [16].…”