AN NA-BH3 COMPLEX OF A [1.1]CRYPTAHEMISPHERAND( COMPLEX AND A BIS)

The [1.1]cryptahemispherand host iaconta-3,5,7(30),8,10,12(31),13,15,1 7(32)-nonaene forms a crystalline complex, (I), with sodium tetrapheny lborate, [Na(C34H44N2O5)]-(C24H20B), and also forms a coordination com plex, (II), with two molecules of BH3, ,31,32-trimethoxy-5,10,15-trime thyl-22,27-dioxa-1, 13,15,17(32)-nonaene}-N-1:N-19-bis(trihydroboron), C34H50B2N2O5, which crystallizes as a CH2Cl2 hemisolvate. The host of (I) complexes Na+ more strongly than it does any other alkali metal i on, consistent with the nearly ideal coordination of Na+ reported here . The N atoms, which are only about 2.6 Angstrom from the Na+ ion. are unusually close to each other in (I), being separated by about 4.63 A ngstrom. The solvent in the structure of (I) is disordered and unident ifiable. The structure of (II) was determined at 115 K. It contains tw o independent molecules in the asymmetric unit, each with site symmetr y m; they have very similar conformations. The BH3 groups attached to the N atoms are directed outward from the cavity of each molecule, giv ing the molecules the uncommon exo-exo conformation. The N atoms in (I I) are about 1.3 Angstrom farther apart than those in (I). Because the N atoms are tetrasubstituted, (II) is a poor complexer. One -CH2CH2OC H2CH2-bridge in each cryptand moiety in (II) adopts a 'crown' conforma tion, while the other bridge has trans -CH2CH2- torsion angles. The ca vity of the host in (II) is filled, and the conformation is stabilized by typical C-H ... O interactions.