Long bonding is a typical bonding feature in noble gas insertion compounds. It has been shown that in the compounds FNgF and HNgX there exists 3c 4e long bonding.In this work, we investigate long bonding in the M Ng C type of noble gas insertion compounds with M = Cu/Ag/Au and Ng = Ar/Kr/Xe/Rn. The effect of C hybridization on bonding was also studied by the compounds MNgCCH, MNgC 2 H 3 , and MNgC 2 H 5 . The structures of these compounds were calculated using MPW1B95, B3LYP-D3, MP2, and DSD-BLYP-D3 methods. It was found that there was indeed