Preparation, reactions, and nuclear magnetic resonance spectra of disubstituted derivatives of the octahydrotriborate(1–) ion, [B₃H₆XX′]^–(X = Cl, X′= Cl, NCS, NCBH₃, or NCBH₂Cl); molecular structure of [B₃H₆Cl₂]^–and partial structure of [B₃H₆Cl(NCS)]^–

Abstract

The preparation of disubstituted derivatives of [ B3Hs]-with halogen or pseudo-halogen is reported.[B,H6CI(NCBH3)]-, and [B3H6CI-(NCBH,CI)] -. N.m.r. parameters show that the ions are fluxional in solution, and B-' B coupling is poorly resolved. The thermal stabilities, and chemical and electrochemical behaviour of representative compounds are described. The molecular structures, illustrated by [ B3H6@I2] -and [ B3H6CI-(NCS)] -relate to that of [B3H8] -with trans substituents. Four molecules of [N(PPh3),] [B,H,Ct,] crystallise in space group P 2 , / c with a = 10.9552(14), b = 12.840(9), c = 24.236(5) A, and p = * The isotropic thermal parameter is defined as exp[ -8n2U(sin28)/ A*].

The structure of methylenetriphenylphosphorane(C–B)triborane(7) at 185 K

“…The stereochemistries of substituted triboranes are delineated by the number and nature of bridging hydrogen atoms. A single H bridge opposite the substituted atom is found in B3HTCO (Glore, Rathke & Schaeffer, 1973), whereas in [B3H6C12]- (Arunchaiya, Morris, Andrews, Welch & Welch, 1984) and [B3H8]-itself (Peters & Nordman, 1960) there are two bridging hydrogen atoms. However, in B3H7NH 3 (Nordman & Reimann, 1959) and [B3H7X]-(X P(l) C(12) = NCS, NCSe; an inter-c(~3) mediate arrangement is observed with a semi-bridging c(14) C(15) H (more closely bound to the substituted atom) in c (16) c(~1) addition to the (opposite) full hydrogen bridge.…”

The chemistry of the octahydrotriborate anion [B3H8]−

“…(Fig. 10) [70,76,77]. The same publication reports some data on the thermal stability and electrochemical properties.…”

“…13. Later it was shown [62,70] that this approach is also suitable for preparing disubstituted B 3 H 6 in a high yield by using a twofold excess of HCl.…”

“…While compar ing the results with those obtained for BH 2 Cl and BHCl 2 [78], the authors assume that this spectral pat tern can correspond to a structure at which both sub stituents are located at the same boron atom. However, subsequently the same research team was able to obtain a single crystal of the compound [70] in which the chlorine atoms occured at different boron atoms in the trans positions (Fig. 15).…”