SYNTHESIS AND CHARACTERIZATION OF DINUCLEAR OXO COMPLEXES OF MOLYBDENUM AND TUNGSTEN WITH CHALCOGENS (O, S, SE, TE) AS BRIDGING LIGANDS

Synthesis of chalcogen rich organometallic complexes of molybdenum and tungsten succeeded in various ways. All complexes described here posses two terminal oxygen ligands. By reaction of SeOCl2 with CpMo(CO)3Na (1) the new compounds trans-Cp2Mo2(O)2(mu-Se)2 (4), cis-Cp2Mo2(O)2(mu-Se)2 (5) and trans-Cp2Mo2(O)2(mu-Se)(mu-O) (6) were produced. Recristallisation of 6 from hexan/CH2Cl2 yielded the compound cis-Cp2Mo2(O)2(mu-Se)0.8(mu-Cl)1.2 (7). The complexes 4 and 5 were also synthesized by the photolytical and thermal reaction of mu-3-AsCp3Mo3(CO)6 (8) with elemental selenium. The reaction of SeOCl2 with CpW(CO)3Na (11) gives trans-Cp2W2(O)2(mu-Se)2 (15). The reaction of Cp2Mo2(CO)4 (9) with As4S4 produced the new compounds cis-Cp2Mo2O3S (18) and trans-Cp2Mo2O3S (19a). The structure of trans-Cp'2Mo2O3S (19b) was determined by X-ray cristallography. The reaction of Cp*2W2(CO)4 (20) with tellurium led to trans-Cp*2W2O2(mu-Te)2 (21). The compounds were characterized by elemental analysis, their spectroscopic data and X-ray diffraction studies.