Table 1.

Calculated (DFT/B3LYP) An–ligand bond orders and An 6p-hole for ionic and organometallic actinide compounds

		NBO-NRT BOs		An-T Covalent NLMO BO decomposition
Compound	BL	An–T	Trs–An	6pσ	2spσ	2pπ	2psσ	Total	An6p-hole
${\left[{\mathrm{U}}^{\mathrm{V}}-\mathrm{N}\right]}^{2+}$	1.75	3.0	–	0.010	0.077	1.392	0.726	2.2	0.03
OThIV−O C2v	1.91	3.0	–	0.003	0.019	0.550	0.422	1.0	0.04
OThIV−O D∞h	1.91	3.0	–	0.006	0.025	0.504	0.442	1.0	0.03
${\left[{\mathrm{OU}}^{\mathrm{VI}}-\mathrm{O}\right]}^{2+}$ C2v	1.70	2.9	–	0.009	0.035	1.042	0.660	1.7	0.06
${\left[{\mathrm{OU}}^{\mathrm{VI}}-\mathrm{O}\right]}^{2+}$ D∞h	1.70	2.9	–	0.022	0.018	0.962	0.753	1.8	0.07
${\left[{\mathrm{ONp}}^{\mathrm{VII}}-\mathrm{O}\right]}^{3+}$	1.67	2.9	–	0.023	0.020	1.262	0.824	2.1	0.09
${\left[{\mathrm{OU}}^{\mathrm{V}}-\mathrm{O}\right]}^{1+}$	1.75	2.9	–	0.015	0.024	0.790	0.688	1.5	0.06
${\left[{\mathrm{ONp}}^{\mathrm{VI}}-\mathrm{O}\right]}^{2+}$	1.68	2.9	–	0.020	0.022	1.022	0.790	1.9	0.08
NUVI−N	1.73	3.5	–	0.016	0.110	1.318	0.948	2.4	0.06
OUVI−C	1.74	3.7	3.3	0.016	0.205	1.956	0.506	2.7	0.05
${\left({\mathrm{R}}^{\mathrm{a}}\right)}_3{\mathrm{NTh}}^{\mathrm{IV}}-\mathrm{Cl}$	2.70	1.1	1.0	0.000	0.017	0.234	0.213	0.5	0.01
${\left[{\left({\mathrm{R}}^{\mathrm{a}}\right)}_3{\mathrm{NTh}}^{\mathrm{IV}}-\mathrm{N}\right]}^{2-}$	1.93	3.6	0.4	0.006	0.172	0.882	0.573	1.6	0.02
${\left({\mathrm{R}}^{\mathrm{a}}\right)}_3{\mathrm{NU}}^{\mathrm{VI}}-\mathrm{N}$	1.80	3.5	0.5	0.009	0.195	1.458	0.873	2.5	0.03
${\left[{\left({\mathrm{R}}^{\mathrm{a}}\right)}_3{\mathrm{NU}}^{\mathrm{V}}-\mathrm{N}\right]}^{1-}$	1.83	3.5	0.5	0.006	0.171	1.276	0.777	2.2	0.02
${\left[{\left({\mathrm{R}}^{\mathrm{a}}\right)}_3{\mathrm{NU}}^{\mathrm{IV}}-\mathrm{N}\right]}^{2-}$	1.83	3.6	0.3	0.006	0.157	1.098	0.695	1.9	0.02
${\left({\mathrm{R}}^{\mathrm{a}}\right)}_3{\mathrm{NU}}^{\mathrm{V}}-\mathrm{O}$	1.85	3.4	0.6	0.004	0.096	0.744	0.458	1.3	0.01
${\left({\mathrm{R}}^{\mathrm{a}}\right)}_3{\mathrm{NNp}}^{\mathrm{V}}-\mathrm{O}$	1.80	3.4	0.6	0.005	0.096	0.792	0.549	1.4	0.02
$\mathrm{Me}{\left({\mathrm{R}}^{\mathrm{b}}\right)}_3{\mathrm{U}}^{\mathrm{VI}}-\mathrm{O}$	1.79	3.3	0.7	0.007	0.109	0.768	0.490	1.4	0.03
${\mathrm{PhCCU}}^{\mathrm{VI}}{\left({\mathrm{R}}^{\mathrm{b}}\right)}_3-\mathrm{O}$	1.81	3.3	0.7	0.006	0.103	0.810	0.486	1.4	0.03
O−UVIC*	1.80	3.3	–	0.009	0.004	0.681	0.580	1.3	0.05
${\left({\mathrm{R}}^{\mathrm{a}}\right)}_3\mathrm{N}-{\mathrm{U}}^{\mathrm{VI}}\mathrm{N}$*	2.46	0.5	3.5	0.000	0.000	0.000	0.218	0.3	0.03
$\mathrm{Me}-{\mathrm{U}}^{\mathrm{VI}}{\left({\mathrm{R}}^{\mathrm{b}}\right)}_3\mathrm{O}$*	2.34	0.7	3.3	0.003	0.000	0.000	0.639	0.7	0.03

Bond length (BL) in Å for the actinide—terminal ligand (An-T) bond. An–T and trans-ligand–actinde (Trs–An) total NBO-NRT bond order (BO; covalent + ionic contributions). Major individual Natural Localized Molecular Orbital (NLMO) contributions to An–T BO. The ionic NBO-NRT BO contributions correspond to a valence bond-type covalent-ionic resonance mixing concept³³. C_2v angle = 120°. 2p_π = sum of 2p_πx and 2p_πy. *Detailed analysis of the Trs–An bond instead of An–T.