As reported in 2019, magnesium monobutadiynide (MgC₄H or Mg–C≡C–C≡C–H) was detected toward IRC +10216 by Cernicharo and co-workers using the IRAM 30m telescope. The detection was based upon experimental work by Forthomme et al. published in 2010. Magnesium monobutadiynide has a dipole moment of 2.1 D.

Most of the magnesium-containing molecules detected to date, including MgC₄H, are linear doublet species. This includes MgNC, MgCN, MgCCH, and MgC₃N (featured last month). Magnesium forms linear X–Mg–Y compounds, such as HMgNC (detected in 2013), because its 3s² pair of electrons is recoupled.