From Borapyramidane to Borole Dianion

Transcription

1 SUPPORTING INFORMATION From Borapyramidane to Borole Dianion Vladimir Ya. Lee, 1 * Haruka Sugasawa, 1 Olga A. Gapurenko, 2 Ruslan M. Minyaev, 2 Vladimir I. Minkin, 2 Heinz Gornitzka, 3 and Akira Sekiguchi 1 * 1 Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki , Japan 2 Institute of Physical and Organic Chemistry, Southern Federal University, Rostov on Don, , Russian Federation 3 LCC-CNRS, Université de Toulouse, CNRS, UPS, Toulouse, France *To whom correspondence should be addressed. leevya@chem.tsukuba.ac.jp (V. Ya. L.), sekiguch@chem.tsukuba.ac.jp (A. S.) Contents of the Supporting Information: 1. Experimenal Section: general procedures, synthetic procedures, spectroscopic and crystallographic data for chloroborapyramidane 2 and borole dianion derivative {3 2 [Li(thf) + ] 2 }, details of the X-ray crystallographic analysis for 2 and {3 2 [Li(thf) + ] 2 } [Figures S1 S11 (NMR spectral charts, ORTEP drawings) and Tables S1 S12 (tables of the crystallographic data including atomic positional and thermal parameters)] S2 S34 2. Computational details: description of the programs, theoretical methods and basis sets used; optimized geometries; AIM results S35 S36 3. References: S37 S38

2 1. Experimental Section. General procedures. All experimental manipulations were performed using high-vacuum line techniques, or in an argon atmosphere of MBRAUN MB 150B-G glove box. All solvents were predried by conventional methods and finally dried and degassed over a potassium mirror in vacuum immediately prior to use. NMR spectra were recorded on Bruker AV-400FT ( 1 H NMR at MHz; 13 C NMR at MHz; 29 Si NMR at 79.5 MHz; 7 Li NMR at MHz; 11 B NMR at MHz) NMR spectrometer. Starting tetrakis(trimethylsilyl)cyclobutadiene dianion dilithium salt 1 2 [Li(thf) + ] 2 was prepared according to a published procedure. 1 (a) Experimental procedure, spectroscopic and crystallographic data for chloro(borapyramidane) 2. BCl 3 (0.415 ml of 1 M solution in heptane, mmol) was added under argon atmosphere to the hexane solution of dilithium salt of the tetrakis(trimethylsilyl)cyclobutadiene dianion 1 2 [Li(thf) + ] 2 (103.2 mg, mmol) in a Schlenk tube equipped with a magnetic stirring bar. After stirring for 10 minutes at room temperature, the solution color changed to orange and white soild percipitated. This solid was filtered off, solvents were evaporated, and the residue was recrystallized from dry hexane to give 2 as pale-yellow (almost colorless) crystals (40.7 mg, 51%). Mp C. 1 H NMR (C 6 D 6, δ, ppm) 0.27 (s, 36 H, 12 Me); 13 C NMR (C 6 D 6, δ, ppm) 0.86 (Me), (skeletal C); 29 Si NMR (C 6 D 6, δ, ppm) (Si substituents); 11 B NMR (C 6 D 6, δ, ppm) 38.55; Anal. Calcd. for C 16 H 36 BClSi 4 : C, 49.65; H, Found: C, 49.60; H, The single crystals of 2 for X-ray diffraction analysis were grown from a hexane solution. Diffraction data were collected at 100 K on a Bruker AXS APEX II CCD X-ray diffractometer (Mo-Kα radiation, λ = Å, 50 kv/30 ma). The structure was solved by the direct method with the SHELXS-97 program 2 and refined by the full-matrix least-squares method with the SHELXL-97 program 3. Crystal data for 2: MF = C 16 H 36 BClSi 4, MW = , orthorhombic, P n m a, a = (7), b = (10), c = (7) Å, V = (2) Å 3, Z = 4, D calcd = g cm 3. The final R factor was for 2425 reflections with I o > 2σ(I o ) (R w = for all data), GOF = The X-ray crystallographic data for 2 have been deposited at the Cambridge Crystallographic Data Centre (CCDC) under deposition no. CCDC These data can be obtained free of charge from the CCDC ( S2

3 (b) Experimental procedure, spectroscopic and crystallographic data for the Chloroborole Dianion Dilithium salt {3 2 [Li(thf) + ] 2 } Chloro(borapyramidane) 2 (60.2 mg, mmol) and Li powder (10.7 mg, 1.54 mmol) were placed in a glass reaction tube with a magnetic stirring bar. Then dry oxygen-free THF (1.5 ml) was introduced into this reaction tube, and the reaction mixture was stirred at room temperature. The solution color gradually changed from pale-yellow to orange. After stirring for 1 day, remaining Li powder was removed by filtration. Then the solvent was removed under vacuum, and the residue was washed by hexane (0.5 ml 3 times). Finally, inorganic salt was removed by extraction of product with toluene, and toluene was then evaporated under vacuum to give {3 2 [Li(thf) + ] 2 } as pale-yellow crystals (almost colorless) (52.4 mg, 62%). Mp C. 1 H NMR (C 7 D 8, δ, ppm) 0.60 (s, 18 H, α-sime 3 ), 0.71 (s, 18 H, β-sime 3 ); 13 C NMR (C 7 D 8, δ, ppm) 5.69 (α-sime 3 ), 6.86 (β-sime 3 ), (br, skeletal C α ), (skeletal C β ); 29 Si NMR (C 7 D 8, δ, ppm) 13.15, 11.53; 7 Li NMR (C 7 D 8, δ, ppm) 6.73; 11 B NMR (C 7 D 8, δ, ppm) 36.31; Anal. Calcd. for C 24 H 52 BClLi 2 O 2 Si 4 : C, 52.88; H, Found: C, 52.03; H, The single crystals of {3 2 [Li(thf) + ] 2 } for X-ray diffraction analysis were grown from a toluene solution. Diffraction data were collected at 100 K on a Bruker AXS APEX II CCD X-ray diffractometer (Mo-Kα radiation, λ = Å, 50 kv/30 ma). The structure was solved by the direct method with the SHELXS-97 program 2 and refined by the full-matrix least-squares method with the SHELXL-2014 program 4. Crystal data for {3 2 [Li(thf) + ] 2 }: MF = C 24 H 52 BClLi 2 O 2 Si 4, MW = , monoclinic, P2 1 /c, a = 9.220(2), b = (3), c = (3) Å, β = (2), V = (10) Å 3, Z = 4, D calcd = g cm 3. The final R factor was for 4934 reflections with I o > 2σ(I o ) (R w = for all data), GOF = The X-ray crystallographic data for {3 2 [Li(thf) + ] 2 } have been deposited at the Cambridge Crystallographic Data Centre (CCDC) under deposition no. CCDC These data can be obtained free of charge from the CCDC ( S3

4 Figure S1. 1 H NMR spectrum of the chloroborapyramidane 2 (C 6 D 6 ). Figure S2. 13 C NMR spectrum of the chloroborapyramidane 2 (C 6 D 6 ). S4

5 impurity Figure S3. 29Si NMR spectrum of the the chloroborapyramidane 2 (C6D6). Figure S4. 11B NMR spectrum of the chloroborapyramidane 2 (C6D6). S5

6 (c) X-ray crystallography of 2. Table S1. Crystallographic data for chloroborapyramidane 2. Identification code BPyr Empirical formula C 16 H 36 BClSi 4 Formula weight Temperature Wavelength Crystal system Space group Unit cell dimensions 100 K Å Orthorhombic P n m a a = (7) Å b = (10) Å c = (7) Å Volume (2) Å 3 Z 4 Density (calculated) g/cm 3 Absorption coefficient mm -1 F(000) 840 Crystal size 0.20 x 0.24 x 0.31 mm 3 Theta range for data collection 2.12 to Index ranges -14<=h<=14, -21<=k<=21, -14<=l<=14 Reflections collected Independent reflections 2513 [R(int) = ] Completeness to theta = % Absorption correction multi-scan Max. and min. transmission and Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 2513 / 0 / 119 Goodness-of-fit on F Final R indices [I>2sigma(I)] R1 = , wr2 = R indices (all data) R1 = , wr2 = S6

7 Figure S5. Crystal structure of the chloroborapyramidane 2 (ORTEP view with the thermal ellipsoids drawn at the 40% probability level), hydrogen atoms are not shown. S7

8 Table S2. Atomic coordinates and equivalent isotropic atomic displacement parameters (Å 2 ) for 2. U(eq) is defined as one third of the trace of the orthogonalized U ij tensor. x y z U(eq) B (14) (15) (3) C (8) (6) (9) (2) C (12) (13) (3) C (12) (12) (3) C (11) (8) (11) (3) C (11) (7) (10) (3) C (11) (7) (12) (3) C (10) (7) (11) (3) C (15) (15) (4) C (13) (8) (11) (3) C (16) (17) (5) Cl (3) (3) (12) Si (3) (17) (3) (10) Si (3) (3) (11) Si (4) (3) (11) S8

9 Table S3. Bond lengths [Å] for 2. B1-C (2) B1-C1# (16) B1-C (16) B1-C (2) B1-Cl (17) C1-C (14) C1-C (14) C1-Si (11) C2-C1# (14) C2-Si (15) C3-C1# (14) C3-Si (15) C4-Si (13) C4-H4A 0.98 C4-H4B 0.98 C4-H4C 0.98 C5-Si (12) C5-H5A 0.98 C5-H5B 0.98 C5-H5C 0.98 C6-Si (13) C6-H6A 0.98 C6-H6B 0.98 C6-H6C 0.98 C7-Si (12) C7-H7A 0.98 C7-H7B 0.98 C7-H7C 0.98 C8-Si (18) C8-H8A 0.98 C8-H8B 0.98 C8-H8C 0.98 C9-Si (13) C9-H9A 0.98 C9-H9B 0.98 C9-H9C 0.98 C10-Si (19) C10-H10A 0.98 C10-H10B 0.98 C10-H10C 0.98 Si2-C7# (12) Si3-C9# (13) Symmetry transformations used to generate equivalent atoms: #1 x, -y+1/2, z Table S4. Bond angles [ ] for 2. C2-B1-C1# (7) C2-B1-C (7) C1#1-B1-C (11) C2-B1-C (10) C1#1-B1-C (7) C1-B1-C (7) C2-B1-Cl (12) C1#1-B1-Cl (5) C1-B1-Cl (5) C3-B1-Cl (12) C3-C1-C (8) C3-C1-B (8) C2-C1-B (8) C3-C1-Si (8) S9

10 C2-C1-Si (8) B1-C1-Si (7) C1#1-C2-C (11) C1#1-C2-B (7) C1-C2-B (7) C1#1-C2-Si (6) C1-C2-Si (6) B1-C2-Si (11) C1#1-C3-C (11) C1#1-C3-B (7) C1-C3-B (7) C1#1-C3-Si (6) C1-C3-Si (6) B1-C3-Si (10) Si1-C4-H4A Si1-C4-H4B H4A-C4-H4B Si1-C4-H4C H4A-C4-H4C H4B-C4-H4C Si1-C5-H5A Si1-C5-H5B H5A-C5-H5B Si1-C5-H5C H5A-C5-H5C H5B-C5-H5C Si1-C6-H6A Si1-C6-H6B H6A-C6-H6B Si1-C6-H6C H6A-C6-H6C H6B-C6-H6C Si2-C7-H7A Si2-C7-H7B H7A-C7-H7B Si2-C7-H7C H7A-C7-H7C H7B-C7-H7C Si2-C8-H8A Si2-C8-H8B H8A-C8-H8B Si2-C8-H8C H8A-C8-H8C H8B-C8-H8C Si3-C9-H9A Si3-C9-H9B H9A-C9-H9B Si3-C9-H9C H9A-C9-H9C H9B-C9-H9C Si3-C10-H10A Si3-C10-H10B H10A-C10-H10B Si3-C10-H10C H10A-C10-H10C H10B-C10-H10C C6-Si1-C (5) C6-Si1-C (6) C1-Si1-C (5) C6-Si1-C (6) C1-Si1-C (5) C4-Si1-C (6) C8-Si2-C7# (5) C8-Si2-C (5) C7#1-Si2-C (8) C8-Si2-C (7) C7#1-Si2-C (5) C7-Si2-C (5) C10-Si3-C9# (6) C10-Si3-C (6) C9#1-Si3-C (9) C10-Si3-C (8) C9#1-Si3-C (5) C9-Si3-C (5) S10

11 Symmetry transformations used to generate equivalent atoms: #1 x, -y+1/2, z Table S5. Anisotropic atomic displacement parameters (Å 2 ) for 2. The anisotropic atomic displacement factor exponent takes the form: -2π 2 [ h 2 a *2 U h k a * b * U 12 ] U 11 U 22 U 33 U 23 U 13 U 12 B (7) (8) (8) (6) 0 C (4) (5) (5) (4) (4) (4) C (6) (7) (7) (5) 0 C (7) (7) (7) (5) 0 C (7) (7) (7) (5) (5) (5) C (6) (6) (6) (5) (5) (5) C (6) (6) (7) (5) (5) (5) C (6) (6) (6) (5) (5) (5) C (8) (13) (8) (6) 0 C (9) (6) (6) (5) (6) (6) C (9) (15) (9) (7) 0 Cl (19) (2) (2) (14) 0 Si (17) (17) (17) (11) (11) (11) Si (2) (2) (2) (15) 0 Si (2) (2) (2) (15) 0 S11

12 Table S6. Hydrogen atomic coordinates and isotropic atomic displacement parameters (Å 2 ) for 2. x/a y/b z/c U(eq) H4A H4B H4C H5A H5B H5C H6A H6B H6C H7A H7B H7C H8A H8B H8C H9A H9B H9C H10A H10B H10C S12

13 Figure S6. 1 H NMR spectrum of the chloroborole dianionic derivative {3 2 [Li(thf) + ] 2 } (thf-d 8 ). Figure S7. 13 C NMR spectrum of the chloroborole dianionic derivative {3 2 [Li(thf) + ] 2 } (thf-d 8 ). S13

14 impurity Figure S8. 29 Si NMR spectrum of the chloroborole dianionic derivative {3 2 [Li(thf) + ] 2 } (thf-d 8 ). Figure S9. 11 B NMR spectrum of the chloroborole dianionic derivative {3 2 [Li(thf) + ] 2 } (thf-d 8 ). S14

15 Figure S10. 7 Li NMR spectrum of the chloroborole dianionic derivative {3 2 [Li(thf) + ] 2 } (thf-d 8 ). S15

16 (d) X-ray crystallography of {3 2 [Li(thf) + ] 2 }. Table S7. Crystallographic data for chloroborole dianionic derivative {3 2 [Li(thf) + ] 2 }. Identification code Diborole_0m Empirical formula C 24 H 52 BClLi 2 O 2 Si 4 Formula weight Temperature Wavelength Crystal system 100 K Å Monoclinic Space group P2 1 /c Unit cell dimensions a = (15) Å b = (3) Å β = (2) c = (3) Å Volume (10) Å 3 Z 4 Density (calculated) g/cm 3 Absorption coefficient mm -1 F(000) 1184 Crystal size x x mm Theta range for data collection to Index ranges -11<=h<=11, -25<=k<=25, -22<=l<=22 Reflections collected Independent reflections 6272 [R(int) = ] Completeness to theta = % Absorption correction empirical Max. and min. transmission and Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 6272 / 206 / 365 Goodness-of-fit on F Final R indices [I>2sigma(I)] R1 = , wr2 = R indices (all data) R1 = , wr2 = S16

17 Figure S11. Crystal structure of the chloroborole dianion derivative {3 2 [Li(thf) + ] 2 } (ORTEP view with the thermal ellipsoids drawn at the 30% probability level), hydrogen atoms are not shown. THF molecule coordinated to the Li2 atom is disordered, and only major occupancy (59%) is shown here. S17

18 Table S8. Atomic coordinates and equivalent isotropic atomic displacement parameters (Å 2 ) for {3 2 [Li(thf) + ] 2 }. U(eq) is defined as one third of the trace of the orthogonalized U ij tensor. x y z U(eq) B(1) 8031(3) 9135(1) 7024(2) 22(1) C(1) 7736(3) 9614(1) 7612(1) 19(1) C(2) 6617(3) 9291(1) 7945(1) 17(1) C(3) 6169(3) 8664(1) 7570(1) 17(1) C(4) 7044(3) 8534(1) 7009(1) 19(1) C(5) 8213(4) 10854(1) 6750(2) 39(1) C(6) 7591(3) 11087(1) 8222(2) 32(1) C(7) 10548(3) 10465(1) 8140(2) 40(1) C(8) 4851(3) 10151(1) 8904(2) 31(1) C(9) 8139(3) 9806(1) 9509(2) 31(1) C(10) 5990(4) 8766(1) 9443(2) 34(1) C(11) 4600(3) 7426(1) 8118(2) 32(1) C(12) 3381(3) 8068(1) 6569(2) 30(1) C(13) 2982(3) 8742(2) 7903(2) 39(1) C(14) 6366(3) 6995(1) 6645(2) 34(1) C(15) 9216(3) 7562(1) 6563(2) 38(1) C(16) 6473(4) 7991(1) 5404(2) 38(1) Cl(1) 9368(1) 9265(1) 6432(1) 35(1) Li(1) 8483(5) 8639(2) 8151(2) 26(1) Li(2) 5650(5) 9445(2) 6765(3) 29(1) O(1) 9678(2) 8144(1) 8930(1) 33(1) C(17) 10954(3) 8360(2) 9495(2) 43(1) C(18) 11916(4) 7758(2) 9674(2) 58(1) C(19) 10774(4) 7211(2) 9630(2) 53(1) C(20) 9509(4) 7435(1) 8998(2) 49(1) O(2) 4369(11) 9981(5) 6107(5) 38(2) C(21) 3606(12) 10526(5) 6364(6) 62(3) C(22) 2022(14) 10490(8) 5882(8) 53(4) S18

19 C(23) 1946(10) 9864(5) 5422(5) 51(3) C(24) 3539(9) 9766(5) 5366(4) 41(2) O(2') 3971(8) 9963(4) 6288(4) 38(2) C(21') 3510(9) 10448(4) 6762(4) 60(2) C(22') 2426(7) 10878(3) 6283(4) 51(2) C(23') 1725(10) 10448(5) 5624(5) 36(2) C(24') 2971(9) 9990(4) 5551(4) 54(2) Si(1) 8501(1) 10468(1) 7708(1) 23(1) Si(2) 6324(1) 9517(1) 8895(1) 21(1) Si(3) 4386(1) 8221(1) 7573(1) 22(1) Si(4) 7205(1) 7797(1) 6426(1) 23(1) Table S9. Bond lengths [Å] for {3 2 [Li(thf) + ] 2 }. B(1)-C(4) 1.513(4) B(1)-C(1) 1.514(4) B(1)-Cl(1) 1.840(3) B(1)-Li(2) 2.224(6) B(1)-Li(1) 2.235(5) C(1)-C(2) 1.467(3) C(1)-Si(1) 1.856(2) C(1)-Li(2) 2.193(5) C(1)-Li(1) 2.234(5) C(2)-C(3) 1.452(3) C(2)-Si(2) 1.872(2) C(2)-Li(1) 2.128(5) C(2)-Li(2) 2.152(5) C(3)-C(4) 1.468(3) C(3)-Si(3) 1.872(2) C(3)-Li(2) 2.131(5) C(3)-Li(1) 2.149(5) S19

20 C(4)-Si(4) 1.854(2) C(4)-Li(1) 2.202(5) C(4)-Li(2) 2.227(5) C(5)-Si(1) 1.875(3) C(5)-H(5A) C(5)-H(5B) C(5)-H(5C) C(6)-Si(1) 1.875(3) C(6)-H(6A) C(6)-H(6B) C(6)-H(6C) C(7)-Si(1) 1.867(3) C(7)-H(7A) C(7)-H(7B) C(7)-H(7C) C(8)-Si(2) 1.869(3) C(8)-H(8A) C(8)-H(8B) C(8)-H(8C) C(9)-Si(2) 1.876(3) C(9)-H(9A) C(9)-H(9B) C(9)-H(9C) C(10)-Si(2) 1.879(3) C(10)-H(10A) C(10)-H(10B) C(10)-H(10C) C(11)-Si(3) 1.872(3) C(11)-H(11A) C(11)-H(11B) C(11)-H(11C) C(12)-Si(3) 1.874(3) C(12)-H(12A) S20

21 C(12)-H(12B) C(12)-H(12C) C(13)-Si(3) 1.873(3) C(13)-H(13A) C(13)-H(13B) C(13)-H(13C) C(14)-Si(4) 1.876(3) C(14)-H(14A) C(14)-H(14B) C(14)-H(14C) C(15)-Si(4) 1.873(3) C(15)-H(15A) C(15)-H(15B) C(15)-H(15C) C(16)-Si(4) 1.871(3) C(16)-H(16A) C(16)-H(16B) C(16)-H(16C) Li(1)-O(1) 1.871(5) Li(2)-O(2) 1.828(11) Li(2)-O(2') 1.902(8) O(1)-C(17) 1.438(3) O(1)-C(20) 1.447(3) C(17)-C(18) 1.495(4) C(17)-H(17A) C(17)-H(17B) C(18)-C(19) 1.513(5) C(18)-H(18A) C(18)-H(18B) C(19)-C(20) 1.504(5) C(19)-H(19A) C(19)-H(19B) C(20)-H(20A) S21

22 C(20)-H(20B) O(2)-C(21) 1.442(10) O(2)-C(24) 1.455(10) C(21)-C(22) 1.519(13) C(21)-H(21A) C(21)-H(21B) C(22)-C(23) 1.510(14) C(22)-H(22A) C(22)-H(22B) C(23)-C(24) 1.508(11) C(23)-H(23A) C(23)-H(23B) C(24)-H(24A) C(24)-H(24B) O(2')-C(21') 1.434(7) O(2')-C(24') 1.441(8) C(21')-C(22') 1.451(8) C(21')-H(21C) C(21')-H(21D) C(22')-C(23') 1.501(9) C(22')-H(22C) C(22')-H(22D) C(23')-C(24') 1.504(10) C(23')-H(23C) C(23')-H(23D) C(24')-H(24C) C(24')-H(24D) S22

23 Table S10. Bond angles [ ] for {3 2 [Li(thf) + ] 2 }. C(4)-B(1)-C(1) 108.5(2) C(4)-B(1)-Cl(1) 125.9(2) C(1)-B(1)-Cl(1) (19) C(4)-B(1)-Li(2) 70.24(18) C(1)-B(1)-Li(2) 68.86(18) Cl(1)-B(1)-Li(2) (19) C(4)-B(1)-Li(1) 68.90(18) C(1)-B(1)-Li(1) 70.16(17) Cl(1)-B(1)-Li(1) (19) Li(2)-B(1)-Li(1) 106.5(2) C(2)-C(1)-B(1) 105.7(2) C(2)-C(1)-Si(1) (17) B(1)-C(1)-Si(1) (18) C(2)-C(1)-Li(2) 68.75(18) B(1)-C(1)-Li(2) 71.06(19) Si(1)-C(1)-Li(2) (16) C(2)-C(1)-Li(1) 66.49(17) B(1)-C(1)-Li(1) 70.24(18) Si(1)-C(1)-Li(1) (18) Li(2)-C(1)-Li(1) (19) C(3)-C(2)-C(1) 110.0(2) C(3)-C(2)-Si(2) (17) C(1)-C(2)-Si(2) (17) C(3)-C(2)-Li(1) 70.95(18) C(1)-C(2)-Li(1) 74.30(18) Si(2)-C(2)-Li(1) (16) C(3)-C(2)-Li(2) 69.40(17) C(1)-C(2)-Li(2) 71.79(18) Si(2)-C(2)-Li(2) (17) Li(1)-C(2)-Li(2) 113.2(2) C(2)-C(3)-C(4) 110.0(2) S23

24 C(2)-C(3)-Si(3) (18) C(4)-C(3)-Si(3) (17) C(2)-C(3)-Li(2) 70.97(18) C(4)-C(3)-Li(2) 73.90(18) Si(3)-C(3)-Li(2) (17) C(2)-C(3)-Li(1) 69.37(17) C(4)-C(3)-Li(1) 72.24(18) Si(3)-C(3)-Li(1) (17) Li(2)-C(3)-Li(1) 113.2(2) C(3)-C(4)-B(1) 105.7(2) C(3)-C(4)-Si(4) (17) B(1)-C(4)-Si(4) (18) C(3)-C(4)-Li(1) 68.35(18) B(1)-C(4)-Li(1) 71.24(19) Si(4)-C(4)-Li(1) (16) C(3)-C(4)-Li(2) 66.81(17) B(1)-C(4)-Li(2) 70.02(19) Si(4)-C(4)-Li(2) (17) Li(1)-C(4)-Li(2) (18) Si(1)-C(5)-H(5A) Si(1)-C(5)-H(5B) H(5A)-C(5)-H(5B) Si(1)-C(5)-H(5C) H(5A)-C(5)-H(5C) H(5B)-C(5)-H(5C) Si(1)-C(6)-H(6A) Si(1)-C(6)-H(6B) H(6A)-C(6)-H(6B) Si(1)-C(6)-H(6C) H(6A)-C(6)-H(6C) H(6B)-C(6)-H(6C) Si(1)-C(7)-H(7A) Si(1)-C(7)-H(7B) S24

25 H(7A)-C(7)-H(7B) Si(1)-C(7)-H(7C) H(7A)-C(7)-H(7C) H(7B)-C(7)-H(7C) Si(2)-C(8)-H(8A) Si(2)-C(8)-H(8B) H(8A)-C(8)-H(8B) Si(2)-C(8)-H(8C) H(8A)-C(8)-H(8C) H(8B)-C(8)-H(8C) Si(2)-C(9)-H(9A) Si(2)-C(9)-H(9B) H(9A)-C(9)-H(9B) Si(2)-C(9)-H(9C) H(9A)-C(9)-H(9C) H(9B)-C(9)-H(9C) Si(2)-C(10)-H(10A) Si(2)-C(10)-H(10B) H(10A)-C(10)-H(10B) Si(2)-C(10)-H(10C) H(10A)-C(10)-H(10C) H(10B)-C(10)-H(10C) Si(3)-C(11)-H(11A) Si(3)-C(11)-H(11B) H(11A)-C(11)-H(11B) Si(3)-C(11)-H(11C) H(11A)-C(11)-H(11C) H(11B)-C(11)-H(11C) Si(3)-C(12)-H(12A) Si(3)-C(12)-H(12B) H(12A)-C(12)-H(12B) Si(3)-C(12)-H(12C) H(12A)-C(12)-H(12C) S25

26 H(12B)-C(12)-H(12C) Si(3)-C(13)-H(13A) Si(3)-C(13)-H(13B) H(13A)-C(13)-H(13B) Si(3)-C(13)-H(13C) H(13A)-C(13)-H(13C) H(13B)-C(13)-H(13C) Si(4)-C(14)-H(14A) Si(4)-C(14)-H(14B) H(14A)-C(14)-H(14B) Si(4)-C(14)-H(14C) H(14A)-C(14)-H(14C) H(14B)-C(14)-H(14C) Si(4)-C(15)-H(15A) Si(4)-C(15)-H(15B) H(15A)-C(15)-H(15B) Si(4)-C(15)-H(15C) H(15A)-C(15)-H(15C) H(15B)-C(15)-H(15C) Si(4)-C(16)-H(16A) Si(4)-C(16)-H(16B) H(16A)-C(16)-H(16B) Si(4)-C(16)-H(16C) H(16A)-C(16)-H(16C) H(16B)-C(16)-H(16C) O(1)-Li(1)-C(2) 140.5(3) O(1)-Li(1)-C(3) 136.6(3) C(2)-Li(1)-C(3) 39.68(12) O(1)-Li(1)-C(4) 141.6(2) C(2)-Li(1)-C(4) 67.04(15) C(3)-Li(1)-C(4) 39.41(12) O(1)-Li(1)-C(1) 150.6(2) C(2)-Li(1)-C(1) 39.21(11) S26

27 C(3)-Li(1)-C(1) 66.07(15) C(4)-Li(1)-C(1) 67.25(15) O(1)-Li(1)-B(1) 152.6(3) C(2)-Li(1)-B(1) 65.95(16) C(3)-Li(1)-B(1) 65.58(16) C(4)-Li(1)-B(1) 39.86(12) C(1)-Li(1)-B(1) 39.60(12) O(2)-Li(2)-C(3) 153.7(4) O(2')-Li(2)-C(3) 138.5(4) O(2)-Li(2)-C(2) 142.6(4) O(2')-Li(2)-C(2) 129.7(3) C(3)-Li(2)-C(2) 39.63(12) O(2)-Li(2)-C(1) 134.0(4) O(2')-Li(2)-C(1) 136.2(3) C(3)-Li(2)-C(1) 67.11(16) C(2)-Li(2)-C(1) 39.45(12) O(2)-Li(2)-B(1) 139.4(4) O(2')-Li(2)-B(1) 155.4(4) C(3)-Li(2)-B(1) 66.08(16) C(2)-Li(2)-B(1) 65.76(16) C(1)-Li(2)-B(1) 40.07(13) O(2)-Li(2)-C(4) 150.9(4) O(2')-Li(2)-C(4) 156.3(3) C(3)-Li(2)-C(4) 39.29(11) C(2)-Li(2)-C(4) 66.19(15) C(1)-Li(2)-C(4) 67.52(16) B(1)-Li(2)-C(4) 39.74(12) C(17)-O(1)-C(20) 109.0(2) C(17)-O(1)-Li(1) 128.3(2) C(20)-O(1)-Li(1) 122.5(2) O(1)-C(17)-C(18) 104.7(3) O(1)-C(17)-H(17A) C(18)-C(17)-H(17A) S27

28 O(1)-C(17)-H(17B) C(18)-C(17)-H(17B) H(17A)-C(17)-H(17B) C(17)-C(18)-C(19) 102.2(3) C(17)-C(18)-H(18A) C(19)-C(18)-H(18A) C(17)-C(18)-H(18B) C(19)-C(18)-H(18B) H(18A)-C(18)-H(18B) C(20)-C(19)-C(18) 103.1(3) C(20)-C(19)-H(19A) C(18)-C(19)-H(19A) C(20)-C(19)-H(19B) C(18)-C(19)-H(19B) H(19A)-C(19)-H(19B) O(1)-C(20)-C(19) 106.4(3) O(1)-C(20)-H(20A) C(19)-C(20)-H(20A) O(1)-C(20)-H(20B) C(19)-C(20)-H(20B) H(20A)-C(20)-H(20B) C(21)-O(2)-C(24) 109.8(8) C(21)-O(2)-Li(2) 121.8(7) C(24)-O(2)-Li(2) 123.5(7) O(2)-C(21)-C(22) 104.6(9) O(2)-C(21)-H(21A) C(22)-C(21)-H(21A) O(2)-C(21)-H(21B) C(22)-C(21)-H(21B) H(21A)-C(21)-H(21B) C(23)-C(22)-C(21) 106.0(9) C(23)-C(22)-H(22A) C(21)-C(22)-H(22A) S28

29 C(23)-C(22)-H(22B) C(21)-C(22)-H(22B) H(22A)-C(22)-H(22B) C(24)-C(23)-C(22) 103.2(9) C(24)-C(23)-H(23A) C(22)-C(23)-H(23A) C(24)-C(23)-H(23B) C(22)-C(23)-H(23B) H(23A)-C(23)-H(23B) O(2)-C(24)-C(23) 101.9(7) O(2)-C(24)-H(24A) C(23)-C(24)-H(24A) O(2)-C(24)-H(24B) C(23)-C(24)-H(24B) H(24A)-C(24)-H(24B) C(21')-O(2')-C(24') 108.8(6) C(21')-O(2')-Li(2) 115.1(5) C(24')-O(2')-Li(2) 136.1(5) O(2')-C(21')-C(22') 107.7(6) O(2')-C(21')-H(21C) C(22')-C(21')-H(21C) O(2')-C(21')-H(21D) C(22')-C(21')-H(21D) H(21C)-C(21')-H(21D) C(21')-C(22')-C(23') 104.1(6) C(21')-C(22')-H(22C) C(23')-C(22')-H(22C) C(21')-C(22')-H(22D) C(23')-C(22')-H(22D) H(22C)-C(22')-H(22D) C(22')-C(23')-C(24') 103.4(6) C(22')-C(23')-H(23C) C(24')-C(23')-H(23C) S29

30 C(22')-C(23')-H(23D) C(24')-C(23')-H(23D) H(23C)-C(23')-H(23D) O(2')-C(24')-C(23') 106.0(6) O(2')-C(24')-H(24C) C(23')-C(24')-H(24C) O(2')-C(24')-H(24D) C(23')-C(24')-H(24D) H(24C)-C(24')-H(24D) C(1)-Si(1)-C(7) (12) C(1)-Si(1)-C(5) (12) C(7)-Si(1)-C(5) (15) C(1)-Si(1)-C(6) (12) C(7)-Si(1)-C(6) (14) C(5)-Si(1)-C(6) (13) C(8)-Si(2)-C(2) (12) C(8)-Si(2)-C(9) (13) C(2)-Si(2)-C(9) (12) C(8)-Si(2)-C(10) (13) C(2)-Si(2)-C(10) (11) C(9)-Si(2)-C(10) 99.65(13) C(3)-Si(3)-C(11) (12) C(3)-Si(3)-C(13) (12) C(11)-Si(3)-C(13) (14) C(3)-Si(3)-C(12) (12) C(11)-Si(3)-C(12) (12) C(13)-Si(3)-C(12) (14) C(4)-Si(4)-C(16) (12) C(4)-Si(4)-C(15) (12) C(16)-Si(4)-C(15) (15) C(4)-Si(4)-C(14) (12) C(16)-Si(4)-C(14) (14) C(15)-Si(4)-C(14) (13) S30

31 Table S11. Anisotropic atomic displacement parameters (Å 2 ) for {3 2 [Li(thf) + ] 2 }. The anisotropic atomic displacement factor exponent takes the form: -2π 2 [ h 2 a *2 U h k a * b * U 12 ] U 11 U 22 U 33 U 23 U 13 U 12 B(1) 28(2) 15(1) 25(2) 1(1) 11(1) -1(1) C(1) 24(1) 10(1) 24(1) -1(1) 6(1) -1(1) C(2) 22(1) 9(1) 20(1) 0(1) 4(1) 4(1) C(3) 23(1) 10(1) 18(1) 1(1) 4(1) 1(1) C(4) 24(1) 10(1) 22(1) -1(1) 6(1) 1(1) C(5) 63(2) 15(1) 44(2) 5(1) 24(2) 0(1) C(6) 43(2) 12(1) 44(2) -3(1) 15(1) 0(1) C(7) 31(2) 24(2) 65(2) -6(1) 10(2) -6(1) C(8) 40(2) 22(1) 35(2) -5(1) 16(1) 5(1) C(9) 41(2) 24(1) 24(1) -4(1) -2(1) 2(1) C(10) 60(2) 19(1) 27(2) 1(1) 16(1) 1(1) C(11) 45(2) 19(1) 34(2) -1(1) 13(1) -10(1) C(12) 29(2) 22(1) 36(2) -3(1) 2(1) -4(1) C(13) 30(2) 34(2) 55(2) -13(1) 17(2) -3(1) C(14) 48(2) 12(1) 48(2) -4(1) 21(2) -3(1) C(15) 43(2) 21(1) 56(2) -7(1) 23(2) 4(1) C(16) 63(2) 25(1) 29(2) -8(1) 14(2) -5(1) Cl(1) 49(1) 21(1) 44(1) -4(1) 30(1) -7(1) Li(1) 28(2) 19(2) 30(2) -2(2) 3(2) 4(2) Li(2) 38(3) 19(2) 27(2) 1(2) 3(2) 2(2) O(1) 38(1) 20(1) 36(1) 3(1) -1(1) 6(1) C(17) 40(2) 42(2) 40(2) 3(1) -4(1) 4(2) C(18) 49(2) 75(3) 48(2) 22(2) 6(2) 29(2) C(19) 86(3) 38(2) 39(2) 13(2) 19(2) 29(2) C(20) 71(3) 22(2) 53(2) 5(1) 13(2) 7(2) O(2) 44(5) 26(3) 39(5) 5(3) -3(3) 7(3) C(21) 82(6) 51(6) 46(6) 8(5) 1(5) 37(5) S31

32 C(22) 43(6) 53(7) 66(10) 19(6) 23(5) 13(6) C(23) 39(5) 70(7) 45(5) 19(4) 13(4) 5(5) C(24) 37(5) 55(6) 30(4) 13(4) 3(3) 8(4) O(2') 41(4) 37(3) 31(3) -5(2) -4(2) 15(3) C(21') 80(5) 51(4) 42(4) -8(3) -1(4) 37(3) C(22') 47(4) 45(4) 56(4) -8(3) 1(3) 15(3) C(23') 26(3) 32(4) 45(5) 12(3) -4(3) -2(3) C(24') 57(5) 61(4) 34(3) -7(3) -7(3) 21(4) Si(1) 28(1) 9(1) 33(1) -2(1) 9(1) -2(1) Si(2) 31(1) 11(1) 21(1) -2(1) 7(1) 2(1) Si(3) 25(1) 14(1) 28(1) -3(1) 9(1) -3(1) Si(4) 33(1) 11(1) 26(1) -5(1) 12(1) -2(1) S32

33 Table S12. Hydrogen atomic coordinates and isotropic atomic displacement parameters (Å 2 ) for {3 2 [Li(thf) + ] 2 }. x y z U(eq) H(5A) H(5B) H(5C) H(6A) H(6B) H(6C) H(7A) H(7B) H(7C) H(8A) H(8B) H(8C) H(9A) H(9B) H(9C) H(10A) H(10B) H(10C) H(11A) H(11B) H(11C) H(12A) H(12B) H(12C) H(13A) H(13B) H(13C) H(14A) S33

34 H(14B) H(14C) H(15A) H(15B) H(15C) H(16A) H(16B) H(16C) H(17A) H(17B) H(18A) H(18B) H(19A) H(19B) H(20A) H(20B) H(21A) H(21B) H(22A) H(22B) H(23A) H(23B) H(24A) H(24B) H(21C) H(21D) H(22C) H(22D) H(23C) H(23D) H(24C) H(24D) S34

35 2. Computations. Geometry optimization, frequency analysis, wave function stability and all related calculations were performed using the Gaussian 09 program.5 After testing some computational levels (B3LYP,6 TPSSh,7 M068 functionals and G**,9 Def2TZVP,10 Def2TZVPP10 basis sets), we chose B3LYP/Def2TZVP (DFT1) and TPSSh/Def2TZVP (DFT2) levels which provide the best agreement of their optimized geometries (Figure S12) with the X-Ray data. The NBO11 and NRT12 analyses were performed using the NBO6.0 program.13 The AIM analysis14 was carried out using the program AIMAll.15 The views of the optimized geometries and molecular orbitals were generated using Chemcraft 1.8 program.16 Isomer relative energies are given with zero-point correction. 2 (C2) [32 (Li+)2] (C2) A (C2) C (C1) Figure S12. Optimized geometries (bond lengths, in Å) at DFT1 (DFT2) levels for 2, [32 (Li+)2] and isomers A and C. Hydrogens atoms are omitted. S35

36 AIM Results. For the model compound 2ʹ, the type of its apex-to-base bonding interactions is difficult to define from the values of their electron density ρ(r) and the Laplacian 2 ρ(r) (Table S13 and Figure S13), and therefore it is better to define it based on the values of the electronic energy density h e (r). 14b,17 Negative values of h e (r) provide evidence for the covalent bonding character and describe the pyramidal bonds as the polar covalent. The same holds true for the B Cl bond in 2ʹ. Electronic energy density is defined by the equation: h e (r) = v(r) + g(r), where v(r) and g(r) are the local potential and kinetic energy densities, respectively. For the covalent bonding, h e (r) < 0. On the other hand, the basal C C bonds in 2ʹ are purely covalent: they have large ρ(r) and negative values of the Laplacian 2 ρ(r). Table S13. Topological analysis of AIM theory (DFT1) for the model compound 2ʹ: ρ(r) electron density at the bond critical point (e/au 3 ); 2 ρ(r) Laplacian of the electron density (e/au 5 ); h e (r) local electron energy (H/au 3 ); BT bond type; I.I. intermediate interaction; C covalent. Pyramidane Pyramidal B C bonds Cl B bond Basal C C bonds ρ(r) 2 ρ(r) h e (r) BT ρ(r) 2 ρ(r) h e (r) BT ρ(r) 2 ρ(r) h e (r) BT 2ʹ ClB[C 4 H 4 ] I.I I.I C 2ʹ Figure S13. Molecular graph of the H-substituted model 2ʹ: bond critical points are shown in red, ring critical points in yellow. S36

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