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Aminolysis of the 2H-pyran-2-ylidenetungsten complex 3 affords amino-1-tungsta-1,3,5-hexatrienes with different structures, depending on the reaction temperature and the type of amine involved. Addition of primary amines RNH2 (4a − d) (R = allyl, n-Bu, CH2Ph, i-Pr) to 3 at −15 °C yields salt-type (3Z)-6-amino-1-tungsta-1,3,5-hexatrienes 5a − d by reversible ring opening of the pyranylidene ring. Addition of 4a − c at 20 °C affords (3Z)-2-amino-1-tungsta-1,3,5-hexatrienes 6a − c by an irreversible ring opening of the pyranylidene ring. Secondary amines RR1NH 8a − c [RR1N = Me2N, 2-(hydroxymethyl)pyrrolidine, pyrrolidine] undergo an irreversible ring opening to 2-amino-1-tungsta-1,3,5-hexatrienes 9a − c. Aminolysis of 3 in the presence of Me3SiCl/Et3N affords acetimino pyranylidene complexes 10, from which (3Z)-2,6-diamino-1-tungsta-1,3,5-hexatrienes 11 are derived upon aminolysis. Thermolysis of 6a in THF/pyridine affords the captodative 1-amino-1,3-hexadien-5-one 12. 2H-Pyran-2-ylidene complex 3, C19H12O7W, was characterized by X-ray diffraction.

Addition of tertiary open-chain enamines R 1 HCdC(NR 2 )Me 7a-e [NR 2 ) pyrrolidine, N(i-Bu) 2 ; R 1) Ph, CO 2 Me, CO 2 Et, CO 2 Bz, CO 2 -t-Bu] to the 1-alkynylcarbene complex (CO) 5 WdC-(OEt)CtCPh (1a) affords novel (1-azoniabutadien-4-yl)carbonylmetalates ( -OC) 5 WC-(OEt)dC[C(dN + R 2 )Me]C(Ph)dCHR 1 (2E)-torquo-8a-f by dichotomy of the CdC(N) bond of 8 at the CtC bond of 1. Compounds (2E)-torquo-8 are stable in solid state but undergo (2E/2Z) isomerization in solution to give compounds (2Z)-torquo-8. X-ray structure analyses are reported of compounds (2E)-torquo-8e, (2E)-torquo-8f, and (2Z)-torquo-8a.

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