SYNTHESIS AND STRUCTURE DETERMINATIONS OF COMPLEXES CONTAINING A 5-MEMBERED LACTAM STRUCTURE-BASED ON ORGANOHYDRAZIDO(2-) LIGANDS

Acid-catalyzed reactions of the hydrazido(2-) complexes cis,mer-[WX(2) (NNH2)(PMe(2)Ph)(3)] (X=Cl, Br) with phthalaldehyde gave the (phthalim idin-2-yl)imido complexes cis,mer-[WX(2)(NNCH2C6H4CO)(PMe(2)Ph)(3)], v ia the condensation of the terminal NH2 group with one of the formyl g roups and the following cyclization to form a phthalimidine ring. Crys tal structure of the chloro complex 3a was unambiguously determined by X-ray analysis. Reaction of 3a with HBr liberated the (phthalimidin-2 -yl)imido ligand as 2-aminophthalimidine in moderate yield, while trea tment of 3a with KOH in THF selectively cleaved the N-N bond to give p hthalimidine. A similar condensation of the hydrazido(2-) complex tran s-[WF(NNH2)(dppe)(2)](+) (8a(+); dppe=Ph(2)PCH(2)CH(2)PPh(2)) with pht halaldehyde resulted in the formation of the diazoalkane complex trans -[WF(NN=CHC6H4CHO)(dppe)(2)](+). However, further treatment of the lat ter complex with AlCl3 afforded the corresponding (phthalimidin-2-yl)i mido complex trans-[WF(NNCH2C6H4CO)(dppe)(2)](+). When 8a(+) and its m olybdenum analogue were reacted with 2,5-dimethoxy-2,5-dihydrofuran in the presence of a catalytic amount of acid, trans-[M(NNCH=CHCH2CO)(dp pe)(2)](+) (11(+); M=Mo, W) was formed as the kinetic product, which g radually isomerized to the thermodynamically more stable compound tran s-[MF(NNCH2CH=CHCO)(dppe)(2)](+) (12(+)). Both 11(+) and 12(+) (M=W) w ere crystallographically characterized, and the mechanism for the isom erization of 11(+) to 12(+) was proposed based on the results of the H -1 NMR measurements.