Structural studies of organoboron compounds. LV. N,N′-Di-tert-butyl-N,N′- dihydroxypropane-1,3-diamine(O-B)ethoxydiphenylborane and N1,N2-di-tert-butyl-N1,N2-dihydroxy-1-phenylpropane-1,3-diamine(N2-O-B)hydroxydiphenylborane

Abstract

The 1,3-propanediamine derivatives N,N′-di-tert-butyl-N,N′-dihydroxy-1,3-propanediamine and N,N′-di-tert-butyl-N,N′-dihydroxy-1-phenyl-1,3-propanediamine have been prepared and reacted with oxybis(diphenylborane) to yield, respectively, the crystalline organoboron compounds N,N′-di-tert-butyl-N,N′-dihydroxypropane-1,3-diamine(O-B)-ethoxydiphenylborane, 5a, and N1,N2-di-tert-butyl-N1,N2-dihydroxy-1-phenylpropane-1,3-diamine(N2-O-B)-hydroxydiphenylborane, 5b. Crystals of 5a are monoclinic, C2/c, a = 35.402(1), b = 9.212(2), c = 18.101(2) Å, β = 116.688(3)°, Z = 8, ρc = 1.079 g cm−3, and crystals of 5b are monoclinic, P21/c, a = 12.899(4), b = 12.571(4), c = 17.412(3) Å, β = 90.02(2)°, Z = 4, ρc = 1.121 g cm−3. The structures were solved by direct methods and were refined by full-matrix least-squares procedures to final R values of 0.047 and 0.041 for 2492 and 3334 reflections with I ≥ 3σ(I), respectively. Compounds 5a and 5b are open-chain hydroxylamine adducts of diphenylborinic acid and ethyl diphenylborinate, respectively. Both of these compounds are stabilized by a system of three intramolecular hydrogen bonds [Formula: see text]. Bond lengths involving the tetrahedrally coordinated boron atoms are: (C)O—B = 1.457(3), (N)O—B = 1.558(3), and C—B = 1.613(4) and 1.615(4) Å for 5a; (H)O—B = 1.475(3), (N)O—B = 1.562(2), and C—B = 1.618(3) and 1.619(3) Å for 5b.