The HOMO–LUMO (HL) gap (eV), Mulliken charges (adsorbed metal and interacted carbon), ground state dipole moment (D) and polarizability of the studied complexes.

Complexes	HL gap (eV)	Charge (metal)	Charge (carbon)	Dipole moment (D)	Polarizability
C1–Al	1.23	0.6413	0.1800	12.74	−157.67
C1–Au	1.50	0.4019	−0.1568	11.65	−166.01
C1–Cu	1.53	0.4596	−0.3588	14.05	−157.43
C1–Ald	2.04	0.4907	−0.0442	4.90	−189.73
C1–Aud	2.00	0.1940	−0.5855	3.88	−184.23
C1–Cud	2.14	0.1345	−0.4021	3.49	−170.42
C2–Al	2.13	0.6331	−0.2906	9.76	−225.41
C2–Au	1.53	0.0043	0.3076	6.73	−209.87
C2–Cu	1.99	0.0043	0.1039	6.62	−213.45
C2–Ald	1.72	0.4783	−0.1641	9.45	−221.84
C2–Aud	2.26	0.0954	−0.0367	6.67	−214.01
C2–Cud	2.34	0.1281	−0.1884	1.10	−197.00
C3–Al	3.01	0.7860	−0.5776	2.56	−234.39
C3–Au	2.71	0.0535	−0.5314	0.50	−237.65
C3–Cu	3.05	0.0138	−0.1889	0.32	−233.01
C3–Ald	2.05	0.4104	−0.1732	2.20	−233.59
C3–Aud	3.05	0.0121	−0.5776	0.80	−240.98
C3–Cud	2.05	0.0138	−0.1889	1.20	−235.74