Onwards reaction of 2a with CO for 14 h at 60 °C in benzene led to 32 (Scheme 1, Figure ). 32 could also be prepared directly from 1a by reaction with a mixture of CNXyl and CO. 32 contains two ethene amidolate ligands derived from cross-coupling of an isocyanide and CO. Each new C2 fragment in 32 originates from a 2:1:1 reaction of hydride:CO:CNXyl. This is the first example of this reactivity at a metal hydride complex and as such the first time a simple unsubstituted ethene amidolate ligand, [OC 1 (H 1 )=C 2 (H 2 )NAr] 2-, has been observed to form from CO. In C6D6 solution, 32 was characterised by diagnostic, non-equivalent, protons of the ethene amidolate moiety H 1 and H 2 which resonate at  = 5.03 (d, JH-H = 2.2 Hz) and 6.29 (d, JH-H = 2.2 Hz) ppm. These correlate with C environments C 1 and C 2 at  = 102.9 and 152.2 ppm respectively. Reaction of 2a with CO allowed synthesis of 13 C-32. C-32 is monotopically labelled at the C 1 position and there is no evidence for inclusion of the isotope at the C 2 position of the ligand or elsewhere. The 1 JC-H and 2 JC-H coupling constants take values of 139. Dissolving crystalline samples of 32 in THF followed by analysis of the resultant sample by 1 H NMR spectroscopy, either in C6D6 or THF, led to significant changes of the resonances assigned to the ethene amidolate ligand, with H 1 and H 2 now resonating at  = 5.42 (d, JH-H = 3.4 Hz) and 5.32 (d, JH-H = 3.4 Hz) ppm respectively. Recrystallisation revealed the formation of 3-THF2, a product of fragmentation of the tetrametallic structure into a single dimagnesium motif (Scheme 1, Figure ). In the solid state, THF preferentially solvates only one of the magnesium centres, leading to an asymmetric structure containing both 4-and 5-coordinate metals. The C 1 -O, C 2 -N, and C 1 =C 2 bond lengths of the ethene amidolate are near identical to those observed in 3 2 . The reaction is non-reversible and attempts to remove THF from 3-THF 2 under high vacuum (1 x 10 -4 mbar) did not lead to reformation of 3 2 .