STRUCTURES AND PROPERTIES OF MOLYBDENUM CARBONYL-COMPLEXES CONTAININGUNINEGATIVE NITROGEN-TRIPOD LIGANDS DERIVED FROM HETEROCYCLIC-COMPOUNDS INCLUDING 1-H-PYRAZOLE AND 1-H-1,2,4-TRIAZOLE

The melt reaction between 1-H-1,2,4-triazole (HTz) and NaBPh4 affords Na(PhBTZ3) while a similar process between HTz and KBH4 gives K(HBTZ3) . The uninegative L anion (L = PhBTZ3 or HBTZ3) reacts with [Mo(CO),] to give [MoL(CO)3]-. Upon addition of electrophiles, [MoL(CO)2(eta3-al lyl)], [MoL(CO)2(NO)], [MOL(CO)3Br], and [MoL(CO)3I] are obtained. Two structures have been characterized by X-ray crystallography: [NEt4][M o(HBPz3)(CO)3], orthorhombic, Pbca, a = 15.832(3), b = 15.799(4), c = 19.388(5) angstrom, Z = 8, R = 0.043, R(w) = 0.031 based on 2591 refle ctions with I > 3.0sigma(I); [N(PPh3)2][Mo(HBTZ3)(CO)3], orthorhombic, Pbca, a = 17.815(3), b = 32.017(2), c = 15.331(3) angstrom, Z = 8, R = 0.044, R(w) = 0.061 based on 5743 reflections with I > 2.0sigma(I). Although comparison of the averaged nu(CO) values reveals the increasi ng order of the electron donativity as HBBz3-<HBTz3-, PhBTz3-<HBPz3-<H BPz3'-, HBPz3-<HBPz3''-, neither structural features nor reactivities show an appreciable substituent effect (i.e., HBTz3- Vs. HBPz3- and H BTz3- vs. PhBTZ3 nickel pseudohalides suggested by Trofimenko et al. s upported strongly by the solid-state structures of [MoL'(CO)3]- (L' = HBPz3-, HBPz'3-, or HBPz3-; Pz'= 3,5-dimethylpyrazol-1-yl; Pz* = 3-me thylpyrazol-1-yl).