| Summary: | The donor-acceptor chemistry of some Groups (IV), (V) and (VI) halides was investigated with a number of ligands. Trimethylamine provided donor complexes with Hf (IV), Mo (V), Mo (II),As (TIT) and Sb (TIT) halides. With Cp2TiCl2, M0OCI4 and AuCl3 trimethylamine was found to act as a reducing agent. The use of MCl4.2NMe7 CM = Zr, Hf) adducts as intermediates in complex synthesis was briefly studied, and the Megtren adducts (MCl2Megtren)z+2Cl~ (M = Ti, Zr, Hf) isolated. Hexamethylphosphoramide (HMPA) gave adducts with both M (IV) (M = Ti, Zr, Hf, Sn) and M CHI) (M = Ti, V, Cr) chlorides. From the TiC14/HMPA system, adducts of 2:1, 1:1 and 1;2 stoichiometries were isolated. CrC13.3HMPA was isolated as both fac and mer isomers. The (Me2N)xCl3_xPS (x = 31,2,3) series are much weaker donors than HMPA* although they provided a number of adducts with hard Lewis acids. Changes in the electronic structure of the phosphoryl and thiophosphoryl ligands that occur on complexation were examined by 1H, 13C, 31p and IR spectroscopy. (Me2N)2CH2 and bis(dipheny1phosphino)methane gave 1:1 adducts with M(IV) halides. The dominant reaction in the CpTi(NMe2)3 and Cp2Zr(Nme2)2/ MX4 systems, however, was group exchange to give the respective CpM halides. Me2Si(NMe2)2 gave both 1:1 adducts (M (IV) = Ti, Zr, Hf, Sn) and group exchange (M = St, Ge, Tij. The donor-acceptor chemistry of Me2SiCl(NMe2) and Cl3Tt(NMe2) was Briefly studied, and was found to be dominated by disproportionation. (CH20)3 and CCHoS)3 act as weak monodentate donors towards hard M (IV) acids. Dynamic behaviour in the SnCl4.2(CH2S)i system was investigated by 'H NMR and interpreted in terms of both ring inversion and donor-site interchange. (MeBNMe)3 was found to act as a bridging bidentate o-donor in (MeBNMe)3.2TiCl4. The substituted oxamides (C0NHR)2 CR = Me. Et), thiooxamides (CSNHR)2 CR = Me, Et) and malonamide CH2CC0NHMe)2 act as chelating 00 or SS donors towards MCI4 (M = Ti, Sn). IR and 'H NMR evidence suggests that the S donor ligands are more strongly bonded than their 0 counterparts.
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