A series of group 4 and group 5 metal aryloxide compounds containing enamidolate or enediamide ligation have been prepared by the intramolecular coupling of ?;2-acyl and 7)2-iminoacyl functional groups. For the group 4 metals reaction of the mono-iminoacyl's (ArO^M^-R'NCRXR) (M = Ti, Ar = 2,6-diisopropylphenyl, R = CH2Ph; M = Zr, Ar = 2,6-di-íerz-butylphenyl, R = CH2Ph) with carbon monoxide (700-1000 psi) leads directly to the corresponding enamidolate (1) with no evidence for the presumed intermediate mixed acyl, iminoacyl compound. However, the isolable bis ?;2-immoacyl compounds (ArO)2M(?;2-R'NCR)2 (M = Ti, Zr, Hf; ArO = 2,6-diisopropyl-, 2,6-diphenyl-, and 2,6-di-íe/7-butylphenyl; R = CH3, CH2Ph) only undergo intramolecular coupling to the corresponding enediamide derivatives (II) on thermolysis in hydrocarbon solvents.In contrast, attempts to prepare a bis qMminoacyl derivative of Ti(OAr-2,6-Ph2)2(r;2-PhNCCH2SiMe3)(CH2SiMe3) (OAr-2,6Ph2 = 2,6-diphenylphenoxide) by addition of PhNC led only to the isolation of a tris-inserted, coupled complex Ti(OAr-2,6Ph2)2[PhNCR=C(CR=NPh)NPh] (III) (R = CH2SiMe3) containing an enediamide chelate with an ¡mine substituent on the carbon backbone. The tantalum bis r;2-iminoacyl Ta(OAr-2,6Me2)3(j;2-xyNCCH2Ph)2 undergoes the clean formation of the enediamide Ta(OAr-2,6Me2)3[xyNC(CH2Ph)=C(CH2Ph)Nxy] (IV) on thermolysis at 110 °C. Single-crystal X-ray diffraction studies on six compounds of types I, II, III, and IV have been carried out. In the enamidolate compounds Ti(OAr-2,6Pri2)2[OC(CH2Ph)=C(CH2Ph)NBu'] (la) and Zr(OAr-2,6Bu'2)2[OC(CH2Ph)=C-(CH2Ph)Nxy] (lb) both molecules were found to contain a pseudotetrahedral geometry about the metal. The 5-membered