Summary of DFT results for the anions [Al(NON^Dipp)(E{16})]⁻ ([1-E]⁻) and K[Al(NON^Dipp)(E{16})] (K[1-E]), for E{16} = O, S, Se, Te.

	[1-O]−	{K[1-S]}4	[1-S]−	{K[VI]}∞	[1-Se]−	[1-Te]−
Al–E{16}/Å (X-ray)	1.6362(14)a	2.0873(7), 2.0957(7), 2.1039(7), 2.0857(7)	2.0760(11)b	2.2253(11)	2.2032(6)c	2.5039(7)d
Al–E{16}/Å (computed)	1.66	2.13	2.11	2.27	2.24	2.46
Difference: computed vs. X-ray (%)	+1.4	+1.2 to + 2.1	+1.6	+2.0	+1.6	−1.8
ΔdAlE (%)	6.5e	Range: 6.1–6.9f	7.4f	5.7g	6.6g	3.4h
ΔχPi	1.83	—	0.97	—	0.94	0.49
NPA charges (q)	q(Al) = +1.93, q(O) = −1.23	—	q(Al) = +1.85, q(S) = −1.26	—	q(Al) = +1.82, q(Se) = −1.23	q(Al) = +1.78, q(Te) = −1.19
Δq = q(Al) − q(E{16})	3.16	—	3.11	—	3.05	2.97
Wiberg bond index (WBI)	[1-O]− = 1.11j	—	[1-S]− = 1.30j	—	[1-Se]− = 1.38j	[1-Te]− = 1.53j
	K[1-O] = 0.91k	—	K[1-S] = 1.15k	—	K[1-Se] = 1.24k	K[1-Te] = 1.44k
Bond critical point (BCP) analysis
ρ(r)/e Å−3	0.115	—	0.076	—	0.068	0.061
∇2ρ(r)/e Å−5	+0.990		+0.290		+0.183	+0.089
Ellipticity, ε	0.033		0.080		0.108	0.139

^aExperimental data from [K{Al(NON^Dipp)(O)}]₂ dimer, [K(1-O)]₂.

^bAl–S bond length from [K(2.2.2-crypt)][Al(NON^Dipp)(S)], [K(2.2.2)crypt][1-S].

^cAl–Se bond length from [K(2.2.2-crypt)][Al(NON^Dipp)(Se)], [K(2.2.2)crypt][VI].

^dAl–Te bond length from THF adduct, K[Al(NON^Dipp)(Te)(THF)], [K(1-Te·THF)].

^eCalculated using the average value of d(Al–O) = 1.74 Å from 35 entries of Al–OH bonds in the CSD.

^fCalculated using the average value of d(Al–S) = 2.59 Å from 12 entries of Al–SH bonds in the CSD.

^gCalculated using the average value of d(Al–Se) = 2.36 Å from 9 entries of Al–SeH bonds in the CSD.

^hCalculated using the average value of d(Al–Te) = 2.59 Å from 4 entries of Al–TePh bonds in the CSD.

ⁱΔχ_P = χ_P(E) − χ_P(Al), where χ_P(Al) = 1.61, χ_P(O) = 3.44, χ_P(S) = 2.58, χ_P(Se) = 2.55, χ_P(Te) = 2.1, according to the Pauling electronegativity scale.

^jWBI values for structures without the potassium counter-ion.

^kWBI values for compounds containing a potassium counter-ion.