MOLECULAR ROUTES TO METAL-CARBIDES, METAL-NITRIDES, AND METAL-OXIDES - 3 - CHEMICAL-VAPOR-DEPOSITION EMPLOYING X3W-ASTERISK-CCME3, WHERE X = CH2CME3, (OBU)-BU-T, AND (OBU)-BU-T-D(9) AND ASTERISK-C = C-12 OR C-13, AND A COMPARISON WITH THE CHEMISTRY OF ((BUO)-BU-T)(3)W-N

Low-pressure (10(-3) Torr) chemical vapor deposition (LPCVD) employing a hot-walled quartz reactor (300-360 degrees C) and silica/quartz or silicon substrates have been carried out with = X3W=(CBu)-Bu-t, where X = CH2CMe3, (OBu)-Bu-t, and OBut-d(9) and C = C-12 and C-13. Thin f ilms formed on SiO2 or Si have been examined by XPS, RES, XRD, SEM, an d SIMS. The volatile components evolved under the LPCVD conditions wer e trapped in an N-2(1)-cooled U-tube packed with glass beads and exami ned by GC-MS and H-1 and C-13 NMR spectroscopy. Gray-black reflective films of amorphous tungsten carbide were formed (320-360 degrees C), w hen X = Me3CCH2, contaminated with 5-9 atom % oxygen. The C-12:C-13 ra tio in the film was ca. 7:1, and the volatile components were Me4C, (M e3CCH3)-C-13 (54 mol % combined), Me2C= CH2 (35 mol %), (Me3CC)-C-13=C CMe3 (6 mol %), and (Me3CCH)-C-13=CHCMe3 (5 mol %) for the LPCVD emplo ying the C-13-labeled alkylidyne carbon. Films grown from ((BuO)-Bu-t) (3)W=CCMe3 were WO2 (determined by XRD after annealing) contaminated w ith some carbon. The volatile components were Me2C=CH2 (45 mol %), (Bu OH)-Bu-t (38 mol %), and Me4C (5 mol %), together with Me3CC=CCMe3, Me 3CCH=CHCMe3, and Me3CCH2CH2CMe3 (totaling ca. 10 mol %). Reactions emp loying (Bu-t-d(9)O)(3)W=CC(CH3)(3) yielded perdeuterated isobutylene a nd tert-butyl alcohol together with (CH3)(3)CCD3, (CH3)(3)CCD=CDC(CH3) (3), and (CH3)(3)CCD2CD2C(CH3)(3). Reactions employing ((BuO)-Bu-t)(3) W=N were less clean because the precursor was less volatile and it dec omposes with sublimation. Nevertheless, the films obtained were predom inately WO2 contaminated with small amounts of C and N (<4%), and the volatile components revealed the presence of NH3, isobutylene, and (Bu OH)-Bu-t. Collectively these results show that the metal-ligand multip le bond is labile to hydrogen-transfer reactions, which may lead to lo ss of the W=X atom. In the case of WC formation, the elimination of Me 3CC=CCMe3 and Me3CCH=CHCMe3 implicate surface chemistry involving C-C coupling of alkylidyne and alkylidene ligands.