On the Nature of Ni…Ni Interaction in Model Dimeric Ni ...BuLi solution (10.85 cm3, 25.0 mmol) was...

On the Nature of Ni…Ni Interaction in Model Dimeric Ni Complex

Radosław Kamiński,a* Beata Herbaczyńska,b Monika Srebro,c Antoni Pietrzykowski,b Artur Michalak,c Lucjan B. Jerzykiewicz,d Krzysztof Woźniaka*

a Department of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warszawa, Poland b Department of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warszawa, Poland c Department of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland d Department of Chemistry, Wrocław University, Joliot-Curie 14, 50-383 Wrocław, Poland * Corresponding authors: Radosław Kamiński ([email protected]), Krzysztof Woźniak ([email protected])

Keywords: nickel complexes, charge density studies, metal-metal bonding, DFT

calculations, orbital analysis

Abstract: A new dinuclear complex (NiC5H4SiMe2CHCH2)2 (2) was prepared by reacting

nickelocene derivative [(C5H4SiMe2CH=CH2)2Ni] (1) with methyllithium (MeLi). Good

quality crystals were subjected to a high-resolution X-ray measurement. Subsequent multipole

refinement yielded accurate description of electron density distribution. Detailed inspection of

experimental electron density in Ni…Ni contact revealed that the nickel atoms are bonded and

significant deformation of the metal valence shell is related to different populations of the d-

orbitals. The existence of the Ni…Ni bond path explains the lack of unpaired electrons in the

complex due to a possible exchange channel.

Supplementary Material (ESI) for PCCP This journal is © the Owner Societies 2011

1. Synthesis of starting materials

1.1. General Information. All reactions and manipulations were carried out under an

atmosphere of dry argon. Solvents were dried with potassium and distilled prior to use.

Chloro(dimethyl)vinylsilane (Sigma-Aldrich) was distilled under an argon atmosphere prior

to use. Solutions of n-butyllithium in heptane and of methyllithium in diethylether (Sigma-

Aldrich) were used as purchased. Cyclopentadiene was prepared by distillation of

dicyclopentadiene (Fluka) (through retro-Diels-Alder reaction). NiBr2·2DME was prepared

by the reaction of nickel powder with bromine in the presence of dimethyl ether (DME). 1H

NMR (400 MHz) spectra were recorded on a Mercury-400BB spectrometer in benzene-d6 at

ambient temperature. Mass spectra (EI, 70 eV) were recorded on an AMD-604 mass

spectrometer. Reactions are presented in Scheme 1S.

H

HSi

Me MeBuLi _

Li+

ClSi

MeMe1

1) BuLi

2) NiBr2 2 DME.

Scheme 1S. Synthesis of the compound 1.

1.2. One-pot synthesis of 1,1’-bis[dimethyl(vinyl)silyl]nickelocene (1). A solution of

10.85 cm3 BuLi (2.3 M in heptane, 25.0 mmol) was added within 1 min with a syringe to a

solution of 2.05 cm3 (25.0 mmol) of freshly distilled cyclopentadiene in 60 cm3 THF at 0°C.

After stirring for 1 h at room temperature, the solution of cyclopentadienyllithium was cooled

to 0°C and 3.45 cm3 (25.0 mmol) of chloro(dimethyl)vinylsilane was added within 1 min. The

orange-yellow solution of dimethyl(vinyl)silylcyclopentadiene was stirred for 1 h at room

temperature. The reaction mixture was then cooled again to 0°C and the second portion of

BuLi solution (10.85 cm3, 25.0 mmol) was added drop by drop. After 1 h at room

temperature, the reaction mixture was cooled to 0°C and transferred slowly (within 10 min) to

a suspension of 5.00 g (12.5 mmol) NiBr2·2DME in 40 cm3 THF. The color of the solution

changed immediately to green. After stirring for 4 h at room temperature the solvent was

removed under reduced pressure. Residue was dissolved in 100 cm3 diethyl ether and 60 cm3

of water was added. After stirring the mixture for 30 min, the organic layer was separated,

solvents were evaporated and the residue was dried under reduced pressure. 50 cm3 of hexane

was added to the green oil and the solution was filtered through a bed of Celite. Hexane was


distilled off and the residue was dried under reduced pressure. 3.91 g (10.9 mmol) of 1,1’-

bis[dimethyl(vinyl)silyl]nickelocene was obtained as a green oil (yield: 87%). M.p. = ca. –

65°C. 1H NMR (benzene-d6, 400.1 MHz): from –200 to 200 ppm no signals. EI-MS m/z: 356

(M+, 70%), 300 (C18H26Si2 + 2H, 12%), 298 (C18H26Si2, 15%), 262 (10%), 244 (10%), 207

(C9H13SiNi, 12%). EI-HRMS: (C18H26Si258Ni) calculated 356.09265, found 356.09354.

1.3. Synthesis of bis[dimethyl(vinyl)silylcyclopentadienylnickel] (2). The solution of

1.00 g (2.8 mmol) of 1 in 20 cm3 of THF and 40 cm3 of diethyl ether was cooled to –75°C.

3.10 cm3 of methyllithium (1.2 M in diethyl ether, 3.7 mmol) was then added drop by drop

within 3 min. After stirring for 1 h the solution was slowly warmed up to room temperature

and stirred for additional 3 h. Next, 50 cm3 of water was added and the mixture was stirred for

20 min. the organic layer was separated, solvents were evaporated and the residue was dried

under reduced pressure. The obtained green solid was re-dissolved in 20 cm3 of heptane and

filtered through a bed of Celite. Dark green crystals of 2 were obtained from this solution at –

30°C (0.48 g, 1.1 mmol, yield 82 %). 1H NMR (benzene-d6, 400 MHz) δ / ppm: 5.64 (s, 1H,

C5H4), 5.51 (s, 1H, C5H4), 5.22 (s, 1H, C5H4), 5.04 (d, JH–H = 15.7 Hz, 1H, trans-CH=CH2),

3.52 (s, 1H, C5H4), 3.44 (d, JH–H = 11.5 Hz, 1H, cis-CH=CH2), 2.46 (dd, JH-H =15.7 and 11.5

Hz, 1H, Si–CH=CH2), 0.78 (s, 3H, Si–CH3), 0.28 (s, 3H, Si–CH3). 13C NMR (benzene-d6,

100.1 MHz) δ / ppm: 93.97, 93.82, 92.55, 91.05, 49.29, 45.59, 2.08, –1.51. EI-MS m/z: 414

(M+, 5%), 356 (M+–Ni, 100%), 300 (C18H26Si2 + 2H, 18%), 298 (C18H26Si2, 16%), 262

(12%), 244 (12%), 207 (C9H13SiNi, 10%). Crystals suitable for high-resolution X-ray

diffraction experiment were obtained by slow re-crystallization from heptane at 0°C.


2. X-ray data collection and refinement

2.1. General. A single crystal high-resolution X-ray data collection for 2 was performed

on a Bruker Kappa APEX II Ultra diffractometer equipped with a TXS rotating anode (MoKα

radiation, λ = 0.71073 Å), multi-layer optics and an Oxford Cryosystems nitrogen gas-flow

apparatus. A single crystal of suitable size was attached to a cactus spine using Paratone N

oil, mounted on a goniometer head 50 (first 12 runs – low angle data) and 40 mm (high angle

data) from the APEX II CCD camera and maintained at a temperature of 90 K. Details of the

data collection are given in Table 1S. The data collection strategy was optimized and

monitored using the appropriate algorithms implemented by the APEX2 program.[1] Only the

ω scans were taken into account, using 0.3° intervals with a counting time of 10 s and 90 s for

low and high angle data respectively, resulting in a total of 8832 frames. Determination of the

unit cell parameters and integration of the raw images was performed with the APEX2 suite of

programs (integration was done by SAINT[1]). The data set was corrected for Lorentz and

polarization effects. The multi-scan absorption correction, scaling and merging of reflections

were done with SORTAV.[2]

2.2. IAM refinement. Structure was solved by direct methods using SHELXS-97[3] and

refined using SHELXL-97[3] using the IAM approximation. The refinement was based on F2

for all reflections except those with very negative F2. Weighted R factors (wR) and all

goodness-of-fit (GooF) values are based on F2. Conventional R factors are based on F with F

set to zero for negative F2. The Fo2 > 2σ(Fo

2) criterion was used only for calculating R factors

and is not relevant to the choice of reflections for the refinement. The R factors based on F2

are about twice as large as those based on F. Scattering factors were taken from the

International Tables for Crystallography.[4] All non-hydrogen atoms were refined

anisotropically. Hydrogen atoms of C–H bonds were placed in idealized positions(all these

hydrogen atoms were visible on difference density maps). The lattice parameters, including

the final R indices obtained by spherical refinement, are presented in Table 1S.

2.3. Multipole refinement. Multipole refinement of 2 was performed with the XDLSM

module of the XD program suite,[5] using the Hansen-Coppens formalism.[6] In this formalism,

the total atomic electron density (of the k-th atom) is a sum of three components:

( ) ( ) ( ) ( )= −=

++=max

0

33 /'')(l

llmklklk

l

lmlklmkkvkkvkckk rdrκRκPrκρκPrρρ rr


where ρc and ρk are spherical core and valence densities, respectively. The third term contains

the sum of the angular functions (dlm) that take into account aspherical deformations. The

angular functions dlm are real spherical harmonic functions, which are normalized for the

electron density. The coefficients Pv and Plm are multipole populations for the valence and

deformation density multipoles, respectively. κ and κ’ are scaling parameters which control

the expansion or contraction of the valence and deformation densities, respectively. In the

Hansen-Coppens formalism, Pv, Plm, κ and κ’ are refinable parameters together with the

atomic coordinates and thermal motion coefficients. Here the P00 parameter was not refined as

it is highly correlated with Pv.

The least-squares multipole refinement was based on F2, with only those reflections with

I > 3σ(I). Atomic coordinates x, y, and z and anisotropic displacement parameters (Uij) for

each atom were taken from the spherical refinement stage and freely refined. Each atom was

assigned core and spherical-valence scattering factors derived from atomic Volkov and

Macchi wave functions[5] A single-ζ Slater-type radial function multiplied by density-

normalized spherical harmonics was used for describing the valence deformation terms. The

multipole expansion was truncated at the hexadecapole (lmax = 4) and quadrupole (lmax = 2)

levels for all non-hydrogen and hydrogen atoms, respectively. The valence-deformation radial

fits were described by the use of their expansion-contraction parameters κ and κ’. The κ

values were refined for non-hydrogen atoms and constrained to 1.20 for hydrogen atoms.

Identical values of the κ’ parameter was used for all l > 0 multipoles for all other non-

hydrogen atoms and kept unrefined at values of 1.20 for hydrogen atoms. No symmetry

constraints were applied. The parameters refined at each stage of the refinement strategy were

as follows: (1) only the scale factor (which was also refined in other stages of the procedure);

(2) the coordinates together with thermal parameters for non-hydrogen atoms were refined

against the high-angle data (sinθ/λ > 0.8 Å–1); (3) coordinates together with isotropic thermal

parameters for hydrogen atoms against the low-angle data (sinθ/λ < 0.6 Å–1); (5) the hydrogen

atom positions were shifted along the bond directions found to the standardized average

neutron values (1.083 Å, 1.059 Å and 1.077 Å for CAr–H, CMe–H and C=C–H bond distances,

respectively[7]; recent paper of Allen and Bruno[8] corrects some of those values using updated

database with 495 968 entries, however, we did not observed significant differences, and thus

the original model is presented here) and the isotropic thermal parameters for the non-

hydrogen atoms at the high-angle data (sinθ/λ > 0.8 Å–1); (6) estimation of anisotropic thermal

parameters for hydrogen atoms was accomplished using the SHADE2 server[9] (see Figure 5S;

such a procedure have been recently shown to be the best approach, at least within the


Hansen-Coppens approximation, for hydrogen atoms treatment[10]); (7) κ parameters for the

non-hydrogen atoms; (8) multipole parameters refined in a stepwise manner; (9) coordinates

and thermal parameters together with all multipole populations; (10) κ and κ’ parameters; (11)

coordinates and thermal parameters together with all multipole populations. Proper

deconvolution of thermal motion from the density features was tested by using the Hirshfeld

rigid-bond test.[11] The differences of mean-squares displacement amplitudes (DMSDA) were

higher than the 0.001 Å2 limit for the Ni–C bonds (this was analyzed previously in the

literature for Fe–Cp[12] and this phenomenon is due to the liability of Cp rings). For the rest of

the bonds the highest DMSDA values are oberved for Si–CMe bonds (probably because of the

mass difference).

According to the above general refinement strategy, several models with different

scattering factors were tested but there were no significant changes in the final electron

density results obtained. The maximum and minimum of residual density were equal to

+0.331 e·Å–3 and –0.264 e·Å–3, respectively. The residual density maps show some deviations

near the nickel atoms (see Figures 1S). The presence of anharmonic vibrations was excluded,

as their refinement did not improve the model in any way. All R-factors and other parameters

characterizing the refinement, residual density maps, static deformation and laplacian maps

are presented in Table 1S and in Figures 1S-5S.


Table 1S. Crystal and refinement data for compound 2.

Formula C18H26Ni2Si2 Molecular mass 415.99 a.u. Measurement temperature (T) 90(2) K Crystal system monoclinic Space group C2/c Unit cell parameters: a 18.1708(7) Å b 6.5265(2) Å c 17.4683(7) Å α 90° β 116.7710(10)° γ 90° Volume (V) 1849.55(12) Å3 Z 4 Calculated density 1.494 g·cm–3 F(000) 872 Crystal size 0.102 × 0.154 × 0.311 mm3 θ range for data collection 2.51 – 50.70° Absorption coefficient (μabs) 2.168 mm–1 (sinθ/λ)max 1.09 Å–1 Index ranges –39 < h < 39

–14 < k < 14 –37 < l < 37

No. of reflections collected / unique 89835 / 9930 Completeness > 99% Rint 3.28 % Absorption correction multi-scan IAM refinement No. reflections / restrains / parameters 9930 / 0 / 100 R(F) / wR(F2) [for I > 2σ(I)] 2.55% / 6.85% R(F) / wR(F2) [for all data] 2.99% / 7.12% GooF 1.114 Largest residual density peak and hole +1.782 e·Å–3 / –0.634 e·Å–3 Multipole refinement No. of reflections [for I > 3σ(I)] / parameters 8383 / 492 = 17.04 R(F] / wR(F2) [for I > 3σ(I)] 1.23% / 1.83% R(F2] / wR(F2) [for I > 3σ(I)] 1.73% / 3.43% R(F] / R(F2) [for all data] 1.76% / 1.78% GooF [for I > 3σ(I)] 1.072 Largest residual density peak and hole +0.331 e·Å–3 / –0.264 e·Å–3


3. Computational details

3.1. ADF calculations. All the results were obtained from the DFT calculations based on

the Becke-Perdew exchange-correlation functional,[13] using the Amsterdam Density

Functional (ADF) program, version 2009.01.[14] A standard double-ζ STO basis with one set

of polarization functions was used for main-group elements, H, C and Si, while a standard

triple-ζ STO basis set was employed for a transition metal, Ni. The 1s electrons of C, as well

as the 1s-2p electrons of Si and Ni were treated as frozen core. Auxiliary s, p, d, f and g STO

functions, centered on all nuclei, were used to fit the electron density and obtain an accurate

Coulomb potential in each SCF cycle. Relativistic effects were considered using the first-

order scalar relativistic correction.[15]

3.2. Energy decomposition scheme. In the Ziegler-Rauk bond energy decomposition

analysis[16] total interaction energy of distorted fragments in a molecule is divided into

following components:

( ) orbPaulielstatorbsterictot EEEEEE Δ+Δ+Δ=Δ+Δ=Δ

The first contribution, stericEΔ , corresponds to the steric interaction between the fragment

considered. It comprises two terms, namely (i) the classical electrostatic interaction between

the promoted fragments, elstatEΔ , and (ii) the Pauli repulsion between the occupied orbitals on

the two fragments, PauliEΔ . The second component is the orbital interaction term, orbEΔ ,

representing the interactions between the occupied molecular orbitals on one fragment with

the unoccupied molecular orbitals of the other fragment as well as mixing of occupied and

virtual orbitals within the same fragment (intra-fragment polarization). This latter term may

be directly linked to the electronic bonding effect coming from the formation of a chemical

bond.

Natural Orbitals for Chemical Valence (NOCV) are obtained by diagonalization of the

deformational density matrix.[17] They can be grouped in pairs ( )kk ϕϕ− , characterized by the

eigenvalues of the opposite sign and the same absolute value, vk. Thus, the NOCV pairs allow

for a decomposition of the differential Δρ, into NOCV contributions, Δρk:[17]

( ) ( ) ( )[ ] ( ) = =

− Δ=+−=Δ2/

1

2/

1

22n

k

n

kkkkk ρνρ rrrr ϕϕ


The picture of the bonding obtained from the deformational density NOCV contributions, is

further enriched by providing the energetic estimations, ( )kEorbΔ , for each Δρk within the

ETS-NOCV method.[17-18] In such a combined scheme the orbital interaction term is expressed

in terms of NOCVs eigenvalues as:

( ) [ ]=

−−=

+−=Δ=Δ2/

1

TS,

TS,

2/

1orborb

n

kkkkkk

n

k

FFνkEE

where TS

,iiF are the diagonal Kohn-Sham matrix elements defined over NOCV with respect to

the transition state (TS) density at the midpoint between density of the molecule and the sum

of fragment densities. This term gives the energetic measure of Δρk that may be related to the

importance of a particular electron flow channel contributing to the bonding between

fragments considered.

3.3. Topological analysis. Bader’s Quantum Theory of Atoms In Molecules[19] (QTAIM)

was applied to perform topological analysis of experimental and theoretical electron density

distributions.. In the framework of this approach Critical Points (CPs) together with the Bond

Paths (BPs) were found as well as valence shell charge concentrations (VSCCs). In order to

determine the nature and relative strength of the bonds, electron density and its Laplacian

were evaluated at the BCPs. Atomic charges, dipoles and sources were calculated by

integrating the respective quantities within the corresponding atomic basins. For theoretically

obtained structures all analyses were carried out with DGRID program,[20] whereas for

experimental data topological analyses were done with XDPROP and TOPXD modules from

the XD package.


4. Supporting maps, plots and figures

(a) (b)

(c)

Figure 1S. Residual density maps for 2 after multipole refinement: (a) Ni(1)Ni(1)#C(3)#

plane; (b) Ni(1)C(10)#C(11)# plane; (c) C(3)C(5)C(6) plane (# – 2-fold symmetry

transformation present in C2/c space group). Contours at ±0.05·n e·Å–3 (n = 1, 2, …). Color

coding: blue solid lines – positive values, red dashed lines – negative values, black dotted line

– zero contour.


(a) (b)

Figure 2S. Static deformation density maps for 2 after multipole refinement: (a)

Ni(1)C(10)#C(11)# plane (# – 2-fold symmetry transformation, contours at ±0.3·n e·Å–3, n =

1, 2, …); (b) C(3)C(5)C(6) plane (contours at ±0.1·n e·Å–3, n = 1, 2, …) Color coding: blue

solid lines – positive values, red dashed lines – negative values, black dotted line – zero

contour.

Figure 3S. Normal probability plot for 2 after final multipole refinement.


Figure 4S. Scale plot for 2 after final multipole refinement.

Figure 5S. SHADE-estimated ADPs for hydrogen atoms (only the asymmetric part is shown).


(a)

(b)

Figure 6S. Isosurface representations of negative electron density Laplacian distributions in

the vicinity of nickel atoms: (a) theoretical data for model system (1566 e·Å–5); (b)

experimental data for complex 2 (1807 e·Å–5).


Figure 7S. Local source function profiles along Ni…Ni bond. The reference point is taken as

the BCP of the nickel…nickel interaction: (a) IAM (red curve) and (b) multipole model (blue

curve). The respective integrated source function contributions for the Ni atom are equal to

about 0.014 e·Å–3 and 0.020 e·Å–3 for the IAM and multipole model, respectively. The

contribution for IAM is clearly much smaller compared with the multipole model (as it could

be concluded from the local source profiles). This might suggest a weaker charge depletion

from the 3rd atomic shell of the Ni atom (i.e. from the region around at 0.45 Å from the

nucleus), as it is anticipated in the IAM, and may explain rather small positive charge on the

metal atom (ca. +0.5 e). Also it suggests that the atomic core is less flexible (in terms of

deformations) for the NiI complexes in comparison with NiII compounds. The detailed

analysis is beyond the scope of this paper and will be published elsewhere.


5. Supporting tables

Table 2S. Maxima and minima of residual density (RMS = 0.047 e·Å–3).

Highest peaks

Height / e·Å–3 Remarks

1 0.33 Random position 2 0.30 0.74 Å from Ni(1) 3 0.29 Random position 4 0.29 0.74 Å from Ni(1) 5 0.20 0.31 Å from Si(2) 6 0.20 Random position 7 0.19 Random position 8 0.18 1.03 Å from Ni(1) 9 0.18 Random position

10 0.18 Random position Deepest

holes Height / e·Å–3 Remarks

1 –0.27 0.73 Å from Ni(1) 2 –0.22 0.71 Å from Ni(1) 3 –0.22 1.04 Å from Si(2) 4 –0.20 Random position 5 –0.19 0.72 Å from Si(2) 6 –0.18 0.39 Å from C(10) 7 –0.18 Random position 8 –0.17 Random position 9 –0.17 0.45 Å from C(8)

10 –0.17 Random position Table 3S. Selected geometrical and topological parameters in BCPs for 2 (a) and optimized

model system (b) (d – bond length, ρ – electron density, # – 2-fold symmetry axis

transformation).

Bond (a) (b)

d / Å ρ / e·Å–3 ∇2ρ / e·Å–5

d / Å ρ / e·Å–3 ∇2ρ / e·Å–5

Ni(1)–Ni(1)# 2.5152(1) 0.235(1) 1.746(1) 2.496 0.297 1.227 Ni(1)–C(3) 2.0975(3) 0.51(1) 5.40(2) 2.079 0.532 5.092 Ni(1)–C(4) 2.1561(3) – – 2.147 – – Ni(1)–C(5) 2.1655(4) 0.48(1) 5.38(2) 2.193 – – Ni(1)–C(6) 2.1575(4) 0.47(1) 5.43(2) 2.206 0.420 5.085 Ni(1)–C(7) 2.0933(4) – – 2.163 – – Ni(1)–C(10)# 2.0048(3) 0.66(2) 6.29(3) 1.995 0.655 5.186 Ni(1)–C(11)# 1.9888(4) 0.61(2) 6.54(4) 1.991 0.659 5.155 Si(2)–C(3) 1.8637(3) 0.87(2) 0.64(7) – – – Si(2)–C(8) 1.8733(4) 0.85(2) 0.29(7) – – – Si(2)–C(9) 1.8646(4) 0.86(2) –2.62(7) – – – Si(2)–C(10) 1.8604(3) 1.00(3) –2.12(8) – – – C(3)–C(4) 1.4282(5) 1.96(3) –16.1(1) 1.435 1.881 -15.141 C(4)–C(5) 1.4221(6) 2.03(4) –14.1(1) 1.417 1.950 -16.334 C(5)–C(6) 1.4291(6) 2.04(3) –18.1(1) 1.435 1.883 -15.329 C(6)–C(7) 1.4125(5) 2.06(3) –15.4(1) 1.412 1.970 -16.647 C(7)–C(3) 1.4556(5) 1.84(3) –12.8(1) 1.438 1.866 -14.973 C(10)–C(11) 1.4103(5) 1.97(3) –12.9(1) 1.407 1.960 -16.414 C(4)–H (4A) 1.083 1.91(7) –19.6(3) 1.086 1.848 -22.462 C(5)–H (5A) 1.083 1.86(7) –17.1(3) 1.088 1.848 -22.544 C(6)–H (6A) 1.083 1.86(7) –18.4(3) 1.088 1.850 -22.578


C(7)–H (7A) 1.083 1.84(7) –20.6 (3) 1.086 1.848 -22.460 C(8)–H (8A) 1.059 1.76(8) –11.3(3) – – – C(8)–H (8B) 1.059 1.66(8) –9.7(3) – – – C(8)–H (8C) 1.059 1.71(8) –10.6(3) – – – C(9)–H (9A) 1.059 1.77(8) –13.9(3) – – – C(9)–H (9B) 1.059 1.71(8) –9.5 (3) – – – C(9)–H (9C) 1.059 1.70(7) –10.5(3) – – – C(10)–H (10A) 1.077 1.89(7) –19.2(3) 1.094 1.815 -21.385 C(11)–H (11A) 1.077 1.85(7) –21.4 (3) 1.091 1.833 -21.809 C(11)–H (11B) 1.077 1.86(7) –18.6(3) 1.094 1.815 -21.373 C(3)–H (3A) – – – 1.086 1.866 -23.055 C(10)–H(10B) – – – 1.091 1.829 -21.619

Table 4S. Cartesian coordinates of model optimized structure illustrated in Figure 3.

Atom x / Å y / Å z / Å C –0.409879 –2.974590 0.588569 C –0.612256 –1.764515 –0.109610 C –1.630277 –1.030290 0.592299 C –2.092205 –1.829774 1.690492 C –1.317459 –3.015602 1.699227 Ni –0.037014 –1.247926 1.910686 C 0.869996 –1.494599 3.665361 C 1.787173 –1.651378 2.609869 H 2.087186 –2.651467 2.283223 H 0.876480 –0.571849 4.246700 H 0.454903 –2.370255 4.173638 H –2.894144 –1.579928 2.379572 H –1.396802 –3.827311 2.419027 H 0.311642 –3.747927 0.334822 H –0.099013 –1.444906 –1.012163 H 2.499686 –0.856154 2.387057 H –2.047514 –0.078662 0.277663 Ni 0.037361 1.246878 1.909713 C –1.784750 1.648941 2.614460 C -0.865017 1.489258 3.667124 C 0.616639 1.761103 –0.111015 C 1.637485 1.035173 0.596884 C 2.089670 1.840289 1.694585 C 1.305759 3.020332 1.698036 C 0.402708 2.971015 0.583977 H 2.890315 1.597124 2.387600 H 1.376490 3.834136 2.416541 H –0.323976 3.737552 0.324353 H 0.109517 1.435929 –1.014921 H –2.085460 2.649900 2.291602 H –0.870137 0.564369 4.245658 H –0.448860 2.363270 4.176580 H 2.061629 0.085003 0.286338 H –2.497680 0.854302 2.390334

6. Additional references

[1] APEX2 package, Bruker AXS, Madison, WI, USA, 2010. [2] a) R. H. Blessing, J. Appl. Cryst. 1989, 22, 396; b) R. H. Blessing, Acta Cryst. 1995,

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On the Nature of Ni…Ni Interaction in Model Dimeric Ni ...BuLi solution (10.85 cm3, 25.0 mmol) was...

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Transcript of On the Nature of Ni…Ni Interaction in Model Dimeric Ni ...BuLi solution (10.85 cm3, 25.0 mmol) was...