Table 2. Comparison of selected experimental and calculated bonding parameters of 1H, 1H_calc and 1H′_calc.

	Si1–Si2 [Å]	Si1–C1 [Å]	Si2–C2 [Å]	∑Si1 c [°]	C1–Si1–Si2–C2 [°]	φ NHC1 d [°]	φ NHC2 d [°]
1H	2.281(3)	1.873(4)	1.873(4)	—	180.0(3)	3.3(2)	3.3(2)
1Hcalc a	2.339	1.885	1.907	335.51	173.69	32.71	1.26
1Hcalc b	2.308	1.861	1.884	342.58	173.63	21.95	3.41
1H′calc b	2.289	1.841	1.886	359.61	179.32	6.68	3.24

^aCalculated at the B3LYP/6-311G**/6-31G* level of theory.

^bCalculated at the B97-D3/RI-JCOSX/def2-TZVP level of theory.

^c∑_Si1 is the sum of angles around the Si1 atom.

^d φ _NHC1 and φ_NHC2 denote the dihedral angles between the least-square plane of the atoms C1, Si1, Si2, C2 and the least square plane of the heterocyclic ring atoms of the NHC substituent bonded to Si1 and Si2, respectively.