1-azonia-2-boratanaphthalenes

The 1-azonia-2-boratanaphthalenes (NH)(BX)C8H6 can be synthesized from 2-aminostyrene and the dihaloboranes XBHal(2) (1-4: X = Cl, Br, iPr, tBu). Further derivatives (NH)(BX)C8H6 are obtained from 1 by replacing Cl by alkoxy or alkyl groups [5-8: X = OMe, OtBu, Me, (CH2)(3)NMe2]. The hydrolysis of 1 gives a mixture of the bis(azoniaboratanaphthyl) oxide [(NH)BC8H6](2)O (9) and the hydroxy derivative (NH)[B(OH)]C8H6 (10). The diboryl oxide 9 crystallizes in the space group C2/c. The lithiation of 4 at the nitrogen atom gives [NLi(tmen)](BtBu)C8H6 (11), which upon reaction with the diborane(4) B2Cl2(NMe2)(2) yields the 1,2-bis(azoniaboratanaphtbyl)diborane B-2[N(BtBu)C8H6](2)(NMe2)(2) (12). The 2-chloro-1-methyl-4-phenyl derivative (NMe)(BCl)-C8H5Ph (13) of the parent (NH)(BH)C8H6 can be synthesized from the aminoborane BCl2(NMePh) and phenylethyne. Substitution of Cl in 13 gives the derivatives (NMe)(BX)C8H5Ph [14-20: X = N(SiMe3)(2), Me, Et, iBu, tBu, CH2SiMe3, Ph] and the reaction of 13 with Li2O affords the bis(azoniaboratanaphthyl) oxide [(NMe)BC8H5Ph](2)O (21). The reaction of 16 or 19 with [(MeCN)(3)Cr(CO)(3)] yields the complexes [{(NMe)(BX)-C8H5Ph} Cr(CO)(3)] (22, 23: X = Et, CH2SiMe3) in which the chromium atom is hexahapto bound to the homoarene part of 16 or 19, respectively. The complex 23 crystallizes in the space group P2(1)/c. Upon reaction of the phenols para-C6H4R(OH) with the aryldichloroboranes ArBCl2 and subsequent condensation of the products with phenylethyne, the 1-oxonia-2-boratanaphthalenes O(BAr)C8H4RPh with R in position 6 and Ph in position 4 are formed (24-26: Ar = Ph, R = H, Me, OMe; 27-29: Ar = C6F5, R = H, Me, OMe). The azoniaboratanaphthalenes 1-23 were characterized by NMR methods.