The 1,2-addition chemistry of alkynes is a key facet of their reactivity and is both widely exploited and well documented. In terms of organometallic compounds, both terminal and internal alkynes insert into M-E bonds (E = H, C, Hal), generating vinyl building blocks of considerable utility in organic synthesis. However, comparatively little is known about the insertion of alkynes into metal-metal bonds. Recent years have seen a limited number of reports of homo-dimetallation by direct insertion into M-M bonds, primarily for main group metals. Braunschweig's dialane system, for example, has been shown to effect the dialumination of but-2yne (Figure ). Isolated compounds formed by direct insertion of alkynes into hetero M-M', or indeed M-E bonds (E = B, Si), are also relatively scarce. Pertinent to this work is the gold silyl system reported by Amgoune and Bourissou, which reacts under 'drastic' conditions with activated alkynes, via insertion into the Au-Si bond (with exclusively syn stereochemistry). Similarly, in 2021, Yamashita et al. reported an isomerization reaction via a retro-1,2-metal shift, in which the first step is syn insertion of an internal alkyne into a gold boryl complex (Figure ). We recently reported the synthesis of a series of compounds containing direct aluminiumgroup 11 bonds, in which an aluminium centre supported by an NON ligand (NON = 4,5-bis(2,6diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) is bound to a group 11 phosphine fragment. Such compounds are among the small number of covalent aluminium-metal bonded species, and thus were perceived as prime candidates for insertion chemistry. Accordingly, it has been reported by ourselves and others that CO 2 can insert into Al-M bonds, producing metallo-carboxylates. We now report the behaviour of the copper aluminyl complex 1 towards alkynes, which sequentially produces both syn and anti dimetallated alkenes bearing a copper and an aluminium group. Furthermore, we show that the differing reactivity of the metal substituents can be exploited, by selectively inserting CO into one of the resulting M-C bonds, to form isolable copper acyl compounds. We chose to focus on studies of copper aluminyl complex 1 in part because of the extensive use of organo-copper and -aluminium reagents in organic synthesis. Treatment of 1 with one equivalent of 3-hexyne (Scheme 1) leads to a rapid reaction giving a single species, characterized by a lone resonance in the 31 P NMR spectrum at 55.5 ppm. The corresponding 1 H spectrum shows two septets corresponding to the Dipp i Pr methine protons, indicating a reduction in symmetry compared to the starting copper aluminyl compound, 1. Two new quartets arising from the CH 2 protons of ethyl groups are found at 2.86 and 2.92 ppm; the signal at 2.86 ppm shows additional coupling ( 4 J PH = 3 Hz) to the P t Bu 3 ligand, consistent with this ethyl group being situated geminal to the [CuP t Bu 3 ] moiety.