Sarah L. Masters,* Asandra J. Atkinson,Amargit Hölblingb and Karl Hasslerb

Gas-phase molecular structure of 1,1,1,2-tetrabromo-2,2-dimethyldisilane: theoretical and experimental investigation of a super-halogenated disilane and computational investigation of the F, Cl and I analogues

Sarah L. Masters,*aSandra J. Atkinson,aMargit Hölblingb and Karl Hasslerb

a Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, New Zealand, 8140. E-mail:

b Institut für Anorganische Chemie, Technische Universität Graz, Stremayrgasse 16, A-8010 Graz, Austria. E-mail:

Supporting Information

Table S1 Nozzle to plate distances (mm), weighting functions (nm-1), correlation parameters, scale factors and electron wavelengths (pm) used in the electron-diffraction study of 1,1,1,2-tetrabromo-2,2-dimethyldisilane.

Table S2 Theoretical geometrical parameters at the HF level with the 3-21G* and 6-31G* basis sets, and at the MP2 level with the 6-31G*, 6-311G* and 6-311+G* basis sets for 1 – 4.

Table S3 Refined and calculated (HF/6-31G*) amplitudes of vibration (u), associated ra distances and corresponding correction values (k) for the rh1 refinement of 1,1,1,2-tetrabromo-2,2-dimethyldisilane.

Table S4 Least squares correlation matrix ( 100) for the GED refinement of 1,1,1,2-tetrabromo-2,2-dimethyldisilane.

Table S5 Experimental gas electron diffraction coordinates from the refinement of 1,1,1,2-tetrabromo-2,2-dimethyldisilane.

Table S6 Calculated coordinates at the MP2/6-311+G* level for 1,1,1,2-tetrafluoro-2,2-dimethyldisilane.

Table S7 Calculated coordinates at the MP2/6-311+G* level for 1,1,1,2-tetrachloro-2,2-dimethyldisilane.

Table S8 Calculated coordinates at the MP2/6-311+G* level for 1,1,1,2-tetrabromo-2,2-dimethyldisilane.

Table S9 Calculated coordinates at the MP2/6-311+G* level for 1,1,1,2-tetraiodo-2,2-dimethyldisilane.

Figure S1 Experimental and final weighted difference (experimental – theoretical) molecular-intensities for 1,1,1,2-tetrabromo-2,2-dimethyldisilane.

Table S1 Nozzle to plate distances (mm), weighting functions (nm-1), correlation parameters, scale factors and electron wavelengths (pm) used in the electron-diffraction study of 1,1,1,2-tetrabromo-2,2-dimethyldisilane.

Nozzle-plate distancea / 249.59 / 94.26
∆s / 1 / 2
smin / 20 / 80
sw1 / 40 / 100
sw2 / 120 / 258
smax / 140 / 300
Correlation parameter / 0.480 / 0.207
Scale factorb / 0.910(6) / 0.876(14)
Electron wavelength / 6.18 / 6.18

aDetermined by reference to the scattering pattern of benzene vapour.

b Values in parentheses are the estimated standard deviations.

Table S2 Theoretical geometrical parameters at the HF level with the 3-21G* and 6-31G* basis sets, and at the MP2 level with the 6-31G*, 6-311G* and 6-311+G*basis sets for 1 – 4.a,b

Parameter / HF/3-21G* / HF/6-31G* / MP2/6-31G* / MP2/6-311G* / MP2/6-311+G*
F3SiSiFMe2
rSi(1)-Si(2) / 229.8 / 233.6 / 232.7 / 233.9 / 234.9
rSi(1)-C(3/7) / 186.2 / 187.4 / 186.7 / 185.9 / 185.9
rSi(1)-X(14) / 160.3 / 160.6 / 163.3 / 162.9 / 163.3
rSi(2)-X(11) / 157.9 / 158.2 / 160.9 / 160.3 / 160.9
rSi(2)-X(12/13) / 157.8 / 157.9 / 160.6 / 160.0 / 160.4
Si(2)-Si(1)-C(3/7) / 109.7 / 110.5 / 110.0 / 109.9 / 109.8
Si(2)-Si(1)-X(14) / 107.2 / 106.3 / 106.8 / 106.6 / 106.0
Si(1)-Si(2)-X(11) / 110.2 / 110.4 / 109.3 / 109.8 / 110.0
Si(1)-Si(2)-X(12/13) / 113.7 / 113.1 / 113.1 / 113.2 / 113.4
Energy (Hartrees) / -1049.7785 / -1055.1196 / -1056.2306 / -1056.5393 / -1056.5624
Cl3SiSiClMe2
rSi(1)-Si(2) / 233.3 / 235.6 / 233.5 / 233.3 / 233.3
rSi(1)-C(3/7) / 187.0 / 187.7 / 187.1 / 186.2 / 186.3
rSi(1)-X(14) / 206.8 / 208.0 / 207.3 / 207.0 / 207.1
rSi(2)-X(11) / 205.0 / 206.2 / 205.9 / 205.2 / 205.2
rSi(2)-X(12/13) / 204.0 / 205.3 / 205.0 / 204.3 / 204.3
Si(2)-Si(1)-C(3/7) / 109.4 / 109.8 / 109.7 / 109.5 / 109.5
Si(2)-Si(1)-X(14) / 106.4 / 106.5 / 106.2 / 106.5 / 106.4
Si(1)-Si(2)-X(11) / 108.7 / 109.1 / 108.8 / 108.8 / 108.6
Si(1)-Si(2)-X(12/13) / 111.9 / 112.1 / 111.6 / 111.7 / 111.7
Energy (Hartrees) / -2483.6530 / -2495.2321 / -2496.1689 / -2496.3751 / -2496.3927
Br3SiSiBrMe2
rSi(1)-Si(2) / 230.9 / 234.0 / 232.1 / 233.6 / 233.7
rSi(1)-C(3/7) / 187.0 / 187.6 / 187.1 / 186.4 / 186.4
rSi(1)-X(14) / 220.7 / 222.9 / 223.0 / 224.0 / 224.1
rSi(2)-X(11) / 219.9 / 222.2 / 222.8 / 223.2 / 223.2
rSi(2)-X(12/13) / 218.5 / 220.6 / 221.1 / 222.0 / 220.0
Si(2)-Si(1)-C(3/7) / 108.6 / 108.9 / 108.3 / 109.5 / 109.4
Si(2)-Si(1)-X(14) / 106.7 / 106.8 / 106.4 / 106.6 / 106.3
Si(1)-Si(2)-X(11) / 105.8 / 106.4 / 105.6 / 107.5 / 107.7
Si(1)-Si(2)-X(12/13) / 111.6 / 112.2 / 112.1 / 111.3 / 111.3
Energy (Hartrees) / -10895.1417 / -10936.8917 / -10937.7654 / -10947.7709 / -10947.7811
I3SiSiIMe2
rSi(1)-Si(2) / 233.7 / 237.3 / 234.5 / 234.4 / 234.4
rSi(1)-C(3/7) / 187.4 / 188.2 / 187.6 / 186.9 / 186.9
rSi(1)-X(14) / 247.9 / 248.5 / 246.8 / 246.5 / 246.5
rSi(2)-X(11) / 247.7 / 248.3 / 246.7 / 246.5 / 246.5
rSi(2)-X(12/13) / 246.1 / 246.7 / 245.1 / 244.9 / 244.9
Si(2)-Si(1)-C(3/7) / 109.2 / 109.8 / 109.7 / 109.7 / 109.7
Si(2)-Si(1)-X(14) / 107.1 / 107.2 / 104.6 / 104.3 / 104.3
Si(1)-Si(2)-X(11) / 106.3 / 107.4 / 107.5 / 107.5 / 107.5
Si(1)-Si(2)-X(12/13) / 111.1 / 111.6 / 110.7 / 110.6 / 110.6
Energy (Hartrees) / -28205.6296 / -702.0173 / -703.0732 / -703.1527 / -703.1549

aAll distances in pm and all angles in degrees. See Figure 1 in the main text for atom numbering.

b For I3SiSiIMe2, calculations beyond HF/3-21G* utilised the SDB-aug-cc-pVTZ effective core potential and basis for iodine.

Table S3 Refined and calculated (HF/6-31G*) amplitudes of vibration (u), associated ra distances and corresponding correction values (k) for the rh1 refinement of 1,1,1,2-tetrabromo-2,2-dimethyldisilane.a,b

Atom pair / ra / uGED / k / ucalc.
u1 / C(3)-H(6) / 109.6(4) / 6.8(8) / 0.2 / 7.5
u2 / C(3)-H(5) / 109.6(4) / 6.8(Tied to u1) / 0.2 / 7.5
u3 / C(3)-H(4) / 109.6(4) / 6.8(Tied to u1) / 0.2 / 7.5
u4 / H(5)...H(6) / 175.4(14) / 12.0(fixed) / 0.9 / 12.0
u5 / H(4)...H(5) / 175.4(14) / 12.1(fixed) / 0.9 / 12.1
u6 / H(4)...H(6) / 175.5(14) / 12.1(fixed) / 1.0 / 12.1
u7 / Si(1)-C(3) / 185.3(3) / 4.3(3) / 0.0 / 5.2
u8 / Si(2)-Br(12) / 220.2(1) / 5.5(1) / 0.0 / 5.0
u9 / Si(2)-Br(11) / 220.2(1) / 5.4(Tied to u8) / 0.0 / 4.9
u10 / Si(1)-Br(14) / 220.2(1) / 5.5(Tied to u8) / -0.0 / 5.0
u11 / Si(1)-Si(2) / 235.5(5) / 6.3(4) / 0.0 / 5.6
u12 / Si(1)...H(4) / 249.9(12) / 11.9(fixed) / 0.9 / 11.9
u13 / Si(1)...H(5) / 249.7(12) / 11.7(fixed) / 0.7 / 11.7
u14 / Si(1)...H(6) / 249.8(12) / 11.7(fixed) / 0.9 / 11.7
u15 / C(3)...C(7) / 303.9(25) / 10.5(fixed) / 0.6 / 10.5
u16 / H(4)...H(10) / 306.2(58) / 33.7(fixed) / -0.6 / 33.7
u17 / H(5)...H(9) / 316.4(62) / 33.2(fixed) / -0.8 / 33.2
u18 / C(3)...H(10) / 325.8(35) / 23.2(fixed) / 1.3 / 23.2
u19 / C(3)...H(9) / 330.4(38) / 22.7(fixed) / 1.1 / 22.7
u20 / C(3)...Br(14) / 335.3(11) / 12.6(17) / 0.6 / 10.4
u21 / Si(2)...C(3) / 344.6(18) / 10.9(fixed) / 0.4 / 10.9
u22 / H(6)...Br(14) / 354.4(22) / 24.4(fixed) / 1.3 / 24.4
u23 / H(5)...Br(14) / 355.2(23) / 23.4(fixed) / 1.1 / 23.4
u24 / Si(2)...H(6) / 358.2(29) / 24.4(fixed) / 1.0 / 24.4
u25 / Si(2)...H(4) / 363.5(28) / 24.0(fixed) / 1.0 / 24.0
u26 / Br(11)...Br(12) / 355.6(3) / 11.4(2) / 0.5 / 10.1
u27 / Br(12)...Br(13) / 355.6(3) / 11.5(Tied to u26) / 0.5 / 10.2
u28 / H(4)...Br(11) / 369.8(41) / 33.3(fixed) / 8.7 / 33.3
u29 / H(4)...H(9) / 361.8(42) / 36.0(fixed) / 4.5 / 36.0
u30 / Si(1)...Br(11) / 365.2(15) / 12.6(12) / 0.6 / 10.5
u31 / Si(2)...Br(14) / 364.7(10) / 12.6(Tied to u30) / 0.7 / 10.5
u32 / H(6)...Br(12) / 386.2(38) / 35.0(fixed) / 9.3 / 35.0
u33 / Si(1)...Br(12) / 382.2(10) / 14.2(Tied to u30) / 0.6 / 11.8
u34 / C(3)...H(8) / 403.8(21) / 11.9(fixed) / 3.3 / 11.9
u35 / C(3)...Br(11) / 412.1(29) / 24.2(28) / 4.7 / 26.3
u36 / C(3)...Br(12) / 431.1(25) / 25.9(Tied to u35) / 5.4 / 28.1
u37 / H(4)...Br(14) / 437.4(11) / 11.8(fixed) / 3.5 / 11.8
u38 / H(4)...H(8) / 430.6(37) / 23.0(fixed) / 4.4 / 23.0
u39 / H(5)...H(8) / 436.3(39) / 22.7(fixed) / 4.3 / 22.7
u40 / Br(12)...Br(14) / 442.8(23) / 37.3(21) / 5.7 / 28.6
u41 / Si(2)...H(5) / 448.1(16) / 12.3(fixed) / 3.3 / 12.3
u42 / H(6)...Br(11) / 437.6(36) / 43.7(fixed) / 4.4 / 43.7
u43 / H(4)...Br(12) / 459.2(34) / 46.2(fixed) / 5.4 / 46.2
u44 / H(6)...H(8) / 494.5(24) / 14.6(fixed) / 5.4 / 14.6
u45 / H(5)...Br(11) / 515.6(30) / 26.7(fixed) / 6.7 / 26.7
u46 / H(5)...Br(12) / 533.5(27) / 28.0(fixed) / 7.4 / 28.0
u47 / C(3)...Br(13) / 533.4(14) / 22.3(fixed) / -4.7 / 22.3
u48 / Br(11)...Br(14) / 548.8(9) / 17.3(6) / -5.3 / 21.0
u49 / H(4)...Br(13) / 558.1(26) / 42.6(fixed) / -4.8 / 42.6
u50 / H(6)...Br(13) / 556.7(27) / 44.4(fixed) / -4.2 / 44.4
u51 / H(5)...Br(13) / 626.3(16) / 24.6(fixed) / 0.9 / 24.6

aDistances in pm. Values in parentheses are the standard deviations in terms of the last digits. See Figure 1 in the main text for atom numbering.

bUnrefined amplitudes of vibration were fixed at the values obtained using the HF/6-31G* force field.

Table S4 Least squares correlation matrix ( 100) for the GED refinement of 1,1,1,2-tetrabromo-2,2-dimethyldisilane.a

p9 / u11 / u26 / u30 / u35 / u40 / k2
p1 / 51
p5 / 77
p7 / -62 / 59
p11 / -65 / -66
u8 / 62 / 79
u20 / 56
u30 / 66

a Only elements with absolute values  50% are shown; k2 is a scale factor.

Table S5 Experimental gas electron diffraction coordinates from the refinement of 1,1,1,2-tetrabromo-2,2-dimethyldisilane. a

Atom / x / y / z
Si(1) / 235.6 / 0.0 / 0.0
Si(2) / 0.0 / 0.0 / 0.0
C(3) / 296.7 / -87.1 / 151.9
H(4) / 267.1 / -192.8 / 155.2
H(5) / 406.2 / -86.3 / 160.3
H(6) / 259.0 / -42.3 / 244.8
C(7) / 296.7 / -87.1 / -151.9
H(8) / 259.0 / -42.3 / -244.8
H(9) / 406.2 / -86.3 / -160.3
H(10) / 267.1 / -192.8 / -155.2
Br(11) / -61.8 / -211.5 / 0.0
Br(12) / -88.9 / 95.2 / 177.7
Br(13) / -88.9 / 95.2 / -177.7
Br(14) / 296.6 / 211.7 / 0.0

a Coordinates are given in pm.

Table S6 Calculated coordinates at the MP2/6-311+G* level for 1,1,1,2-tetrafluoro-2,2-dimethyldisilane. a

Atom / x / y / z
Si(1) / -47.8 / 107.6 / 0.0
Si(2) / 42.8 / -109.1 / 0.0
C(3) / 1.8 / 196.6 / 155.5
H(4) / 110.5 / 207.1 / 162.1
H(5) / -41.5 / 297.1 / 157.9
H(6) / -32.2 / 143.6 / 244.9
C(7) / 1.8 / 196.6 / -155.5
H(8) / -32.2 / 143.6 / -244.9
H(9) / -41.4 / 297.1 / -157.9
H(10) / 110.5 / 207.1 / -162.1
F(11) / 203.6 / -101.5 / 0.0
F(12) / 1.8 / -195.4 / -128.9
F(13) / 1.8 / -195.4 / 128.9
F(14) / -210.0 / 88.6 / 0.0

a Coordinates are given in pm.

Table S7 Calculated coordinates at the MP2/6-311+G* level for1,1,1,2-tetrachloro-2,2-dimethyldisilane. a

Atom / x / y / z
Si(1) / -139.5 / 45.8 / -0.0
Si(2) / 88.2 / -4.9 / 0.0
C(3) / -182.3 / 138.8 / 155.6
H(4) / -128.6 / 234.1 / 160.2
H(5) / -289.5 / 160.7 / 158.8
H(6) / -157.4 / 81.4 / 245.2
C(7) / -182.3 / 138.8 / -155.6
H(8) / -157.4 / 81.4 / -245.2
H(9) / -289.5 / 160.7 / -158.8
H(10) / -128.6 / 234.1 / -160.2
Cl(11) / 194.5 / 170.6 / -0.0
Cl(12) / 141.9 / -111.5 / -165.8
Cl(13) / 141.9 / -111.5 / 165.8
Cl(14) / -239.7 / -135.4 / 0.0

a Coordinates are given in pm.

Table S8 Calculated coordinates at the MP2/6-311+G* level for 1,1,1,2-tetrabromo-2,2-dimethyldisilane. a

Atom / x / y / z
Si(1) / -135.6 / 113.6 / 0.0
Si(2) / 66.2 / -4.3 / 0.0
C(3) / -148.0 / 215.2 / 155.8
H(4) / -68.0 / 289.8 / 159.9
H(5) / -243.7 / 268.2 / 159.0
H(6) / -141.3 / 153.0 / 245.3
C(7) / -148.0 / 215.2 / -155.8
H(8) / -141.3 / 152.9 / -245.3
H(9) / -243.7 / 268.2 / -159.0
H(10) / -68.0 / 289.8 / -159.9
Br(11) / 232.1 / 144.9 / 0.0
Br(12) / 85.4 / -131.3 / 181.0
Br(13) / 85.4 / -131.3 / -181.0
Br(14) / -298.5 / -40.4 / 0.0

a Coordinates are given in pm.

Table S9 Calculated coordinates at the MP2/6-311+G*//SDB-aug-cc-pVTZ level for 1,1,1,2-tetraiodo-2,2-dimethyldisilane. a,b

Atom / x / y / z
Si(1) / -115.5 / 0.0 / 156.9
Si(2) / 59.7 / 0.0 / 1.1
C(3) / -109.2 / -156.6 / 258.7
H(4) / -16.8 / -160.5 / 317.4
H(5) / -194.1 / -160.2 / 327.9
H(6) / -113.5 / -245.4 / 195.2
C(7) / -109.2 / 156.6 / 258.7
H(8) / -113.5 / 245.4 / 195.2
H(9) / -194.1 / 160.2 / 327.9
H(10) / -16.8 / 160.5 / 317.4
I(11) / 271.3 / 0.0 / 127.6
I(12) / 50.1 / -200.5 / -139.2
I(13) / 50.1 / 200.5 / -139.2
I(14) / -319.8 / 0.0 / 18.9

aThe SDB-aug-cc-pVTZ basis set and ECP were used on the iodine atoms, with 6-311+G* on C, Si and H.

b Coordinates are given in pm.

Figure S1 Experimental and final weighted difference (experimental – theoretical) molecular-intensities for 1,1,1,2-tetrabromo-2,2-dimethyldisilane.