THE MAGNETIC AND 2ND-ORDER NONLINEAR-OPTICAL PROPERTIES OF SOME PARAMAGNETIC SALTS CONTAINING METALLOCARBABORANE ANIONS

A series of air-stable salts containing the paramagnetic metallocarbor anes [MCb2](-) (M = Fe, Ni; Cb2- = 7,8-C2B9H112-) has been prepared an d their magnetic properties investigated. The paramagnetic salts [Fe(I II)Tp(2)][(FeCb2)-Cb-III] {Tp = HB(C3H3N2)(3)}, [Fe-III{C6H4(O)C(ME) = N(CH2)(2)NHCH2}(2)][(FeCb2)-Cb-III, [C5H5NMe][(FeCb2)-Cb-III], [4-MeC 5H4NMe][(FeCb2)-Cb-III], [4-PhC5H4NMe][(FeCb2)-Cb-III], [C9H7NMe][(FeC b2)-Cb-III], [Fe(III)Tp(2)][TCNQ] and [(FeCp2)-Cp-III][(FeCb2)-Cb-III] have been isolated. Magnetic susceptibility measurements show that th ese salts exhibit typical paramagnetic behaviour with no evidence of c ooperative magnetic interactions over the temperature range 6-300 K. T he salts [E-Fc-Ch = CH-p-C5H4NMe][(MCb2)-Cb-III] (M = Fe, Ni, Co) were also synthesised and their their second-order nonlinear optical prope rties assessed using the Kurtz powder test. Only the cobalt-containing complex gave detectable, though weak, second harmonic generation of 0 .01 times urea at 1.907 mum. The salt [C5H5NMe][(FeCb2)-Cb-III] exhibi ts SHG with an effciecy of 0.5 times urea at 1.907 mum and 0.1 at 1.06 4 mum. Mass spectrometric and C-13{H-1} NMR studies of the products fo rmed by the degradation of [Co(Cb)(2)](-) by base in the presence of C o2+ ions has provided no evidence for the formation of higher oligomer s than the previously reported [{Co(Cb)}(2)(C2B8H10)](2-) and [{CoCb(C 2B8H10)}(2)Co](3-). The structures of [(FeCp2)-Cp-III][(NiCb2)-Cb-III ] (Cp- = eta(5)-C5Me5) and [4-MeC5H4NMe][(FeCb2)-Cb-III] have been de termined by single crystal X-ray diffraction studies. (C) 1997 Elsevie r Science S.A.