Theoretical investigation of M≡E bonds in transition metal-ylidyne complexes trans-[H(PMe3)4M≡ER] (M = Mo, W; E = Si, Ge, Sn, Pb; R = Mes, Xylyl)

► Values of various energy terms decreases via Si > Ge > Sn > Pb. ► The electrostatic interaction is almost equal to the orbital interactions. ► The σ-bonding interactions are significantly weaker. ► The π back-donation is the most dominant interaction in the studied complexes.