Supporting Information

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1 Supporting Information Wiley-VCH Weinheim, Germany

2 Synthesis and Properties of the THF Solvates of Extremely Soluble Bis(2,4,6-trimethylphenyl)calcium and Tris(2,6-dimethoxyphenyl)dicalcium iodide Reinald Fischer, Martin Gärtner, Helmar Görls, Lian Yu, Markus Reiher and Matthias Westerhausen 1 Methodology In order to evaluate possible structures of the oligomeric phenyl calcium iodide we investigated several possible structures of the phenyl calcium iodide dimer (see Figure below) and of higher oligomers. The structures were optimized with density functional theory (DFT) and second order MØller Plesset perturbation theory (MP2). Figure 1: Starting structures for the optimization procedures of the phenyl calcium iodide dimer.

3 All calculations were performed with the quantum chemical program package Turbomole [1, 2] employing DFT and MP2/RI [3]. In the DFT calculations we applied the BP86 density functional [4, 5] in combination with the resolution-of-the-identity ( RI ) density fitting technique and the B3LYP density functional [6, 7]. Furthermore the TZVP basis set by Schäfer et al. [8] was used, which features a valence triple-zeta basis set with polarization functions on all atoms. Additional calculations were carried out with Ahlrichs TZVPP basis set, which is triple-zeta basis set for the valence orbitals and includes successively larger shells of polarization functions. The basis set superposition error error has not been taken into account because this error is significantly reduced by the comparatively large TZVPP basis set (especially in the case of the DFT calculations). For the iodine atom, a scalar relativistic effective core potential from the Stuttgart group was employed [9]. For the calculation of partial charges, we applied the Mulliken analysis [10] and the modified Löwdin analysis [11], denoted as Löwdin*, for which the basis set was first orthonormalized within the functions centered on one atom and then subjected to the usual Löwdin orthonormalization procedure. Details on the implementation of this protocol into the Turbomole program package can be found in Ref. [12]. The optimized structures obtained with BP86/RI/TZVP have been confirmed to be local minima in the potential energy hyper surface by frequency calculations with the program package SNF [13]. All molecular structures were visualized with the program Molden [14]. 2 Studies on CaPhI oligomers After optimizing all structures depicted in Figure 1, we obtain four different final structures. Starting an optimization from structures 2, 3, 4 and 7 results in the same final structure, as far as the density functional calculations are concerned. The optimization with MP2 yields only three different structures, because starting the optimization from structures 2, 3, 4, 6 and 7 also results in the same final structure. As shown in Figure 2, structures 3 and 6 are energetically more stable than structures 1 and 5. The rearrangement energy for structure 5 to structure 3 is about -50 kj/mol in DFT calculations (it is almost independent of the density functional), while MP2 calculations yield kj/mol. Since MP2 is able to describe the contribution of dispersion interactions built up by the phenyl groups coordinating to calcium atoms, we may assume that the MP2 results provide a better estimate. The SNF calculations yield exclusively positive vibrational frequencies for all BP86/RI/TZVP optimized dimer structures (compare also Figure 3 for the resulting thermochemical quantities). All BP86/RI/TZVP dimer structures turned out to be local minima. The point group of the global minimum for structure 3 is C2h (see Figure 4). The geometry of this structure indicates that two? 6 bonds exist between calcium atoms and the phenyl substituent. It is mainly due to these two? 6 bonds that the structure constitutes the most stable dimer depicted in Figure 2. Figure 5 shows the electronic energy differences in kj/mol for three particular formations of a monomer and the most stable dimer. These results suggest that the energy of the? 6 bond can be estimated to be at least 130 kj/mol (DFT) or stronger (up to 170 kj/mol with MP2). Figure 6 shows the optimized structure of the cyclic tetramer in S4 symmetry. Figure 7 gives

4 the electronic energy differences in kj/mol for the formation of the tetramer. This tetrameric structure is only about 50 kj/mol more stable than the two separated dimers of structure 3. After determination of the cyclic tetramer structure, we tried to construct other ring structures, which turned out to be by far less favorable or even impossible due to steric effects. Figure 8 and 9 display the electronic energy differences for the PhCaI monomer by successively adding the solvent molecule methylether and THF respectively. According to these results, a phenyl calcium iodide can maximally correspond with four methylether molecules or four THF molecules in the solvent respectively. Figure 10 shows the optimized PhCaI(THF)4 and PhCaI(Me2O)4 structures obtained with BP86/RI/TZVP, they are similar to the X-ray structure of PhCaI(THF)4. Figure 11 shows that an interaction with four THF molecules is energetically favored in comparison to the formation of oligomers. However, one must take into account, that the uncoordinating solvent molecule on the right hand side of the reactions can coordinate to the oligomers and stabilize them. If this solvation provides only 40 kj/mol per THF molecule, the overall reaction energy would be close to zero. Tables 1, 2, 3 and 4 show structural parameters and partial charges for the optimized dimer structures. According to the results from the larger TZVPP basis sets, the partial charges of calcium and iodine atoms are about +1.7 and -0.8, respectively. 2 Studies on Ph2Ca oligomers Figure 12 shows the formation energies for the Ph2Ca dimer in kj/mol starting from three monomer structures calculated with BP86/RI/TZVPP. Comparing to the results of Figure 5, the dimer structures of Ph2Ca and PhCaI are similar and they have the same point group symmetry C2h. The formation energy of the Ph2Ca dimer starting from two standard monomers is about 190 kj/mol (DFT) or up to 237 kj/mol (MP2), which is a little less exothermic then in the case of PhCaI. In the case of the Ph2Ca dimmer, the energy of the? 6 bond can be estimated to be 144 kj/mol with MP2 (or 113 kj/mol with DFT). The energy of the s bond between the phenyl ligand and Ca is about 175 kj/mol with DFT or up to 187 kj/mol with MP2. Figure 13 gives the structure of the cyclic Ph2Ca tetramer and the formation energies obtained from BP86 calculations. By comparison with the results of Figure 7, we can see that both cyclic tetramer structures of Ph2Ca and PhCaI are very similar (point group S4). Moreover, we also obtained similar formation energies in both cases. Figure 14 shows the electronic energy differences for a Ph2Ca monomer by successively adding solvent molecules (THF and methylether). Comparing the data of Figures 8 and 9, we again note the similarity of the results obtained for both cases.

5 Figure 2: BP86/TZVPP and B3LYP/TZVPP optimized dimer structures and corresponding electronic energy differences in kj/mol at 0 K (energy differences from B3LYP/TZVPP are given in parentheses). For comparison, energy differences from single-point MP2/RI/TZVPP calculations on MP2/RI/TZVP optimized structures are given in brackets. [-] indicates that it was not possible to optimize the structure in the upper right corner with MP2.

6 Figure 3: Gibbs free enthalpies and enthalpies (given in parentheses) for rearrangement reactions from the BP86/RI/TZVP calculations in kj/mol at K and kpa. Figure 4: BP86/TZVPP optimized PhCaI dimer structure.

7 Figure 5: Electronic energy differences from the BP86/TZVPP calculations in kj/mol at 0 K. For comparison, energies obtained with B3LYP/TZVPP and MP2/RI/TZVPP are given in parentheses and brackets, respectively. The single-point energy values of MP2/RI/TZVPP were carried out on MP2/RI/TZVP optimized structures. Figure 6: Optimized structure of the cyclic tetramer of PhCaI obtained with BP86/TZVPP.

8 Figure 7: Electronic energy differences for the formation of the cyclic tetramer of PhCaI from BP86/TZVPP calculations in kj/mol at 0 K. Figure 8: Electronic energy differences in kj/mol at 0 K obtained with BP86/TZVPP for successively added solvent molecules (methylether). The energy differences show no clear trend with increasing number of solvent molecules because of the different C(phenyl) Ca I angles in the optimized structures induced by the solvent molecules. The energy value in parentheses denotes the average reaction energy per solvent molecule.

9 Figure 9: Electronic energy differences in kj/mol at 0 K obtained with BP86/TZVPP for successively added solvent molecules of THF. The energy value in parentheses denotes the average reaction energy per solvent molecule. Figure 10: The optimized PhCaI(THF)4 and PhCaI(Me2O)4 structures obtained with BP86/RI/TZVP and selected bond distances in Angstrom and angles in degree are shown. For comparison, the experimental data [15] are given in parentheses.

10 Figure 11: Solvation versus oligomerization: Electronic energy differences in kj/mol obtained with BP86/TZVPP at 0 K. Note that the endothermic reaction energies should be understood as upper bounds because the freed THF molecules might still solvate the resulting oligomers and the true energies would thus be much smaller.

11 Figure 12: Electronic energy differences for the formation of Ph2Ca dimer from the BP86/TZVPP calculations in kj/mol at 0 K. For comparison, energies obtained with B3LYP/TZVPP and MP2/RI/TZVPP are given in parentheses and brackets, respectively. The single-point energy values of MP2/RI/TZVPP were carried out on MP2/RI/TZVP optimized structures.

12 Figure 13: Electronic energy differences in kj/mol at 0 K for the formation of the cyclic tetramer of Ph2Ca obtained with BP86/RI/TZVPP calculations.

13 Figure 14: Electronic energy differences in kj/mol at 0 K obtained with BP86/RI/TZVP calculations for successively added solvent molecules of THF and methylether. The energy value in parentheses denotes the average reaction energy per solvent molecule.

14 Table 1: Structural parameters of the optimized structure 5. For HF/TZVPP * the data are obtained with the MP2/RI/TZVP optimized structures. Figure 12: BP86/TZVPP optimized structure 5

15 Table 2: Structural parameters of the optimized structure 1. For HF/TZVPP * the data are obtained with the MP2/RI/TZVP optimized structures. Figure 13: BP86/TZVPP optimized structure 1

16 Table 3: Structural parameters of the optimized structure 3. For HF/TZVPP * the data are obtained with the MP2/RI/TZVP optimized structures. Figure 14: BP86/TZVPP optimized structure 3

17 Table 4: Structural parameters of the optimized structure 6. Figure 15: BP86/TZVPP optimized structure 6

18 Table 5: Structural parameters of the optimized Ph2Ca dimmer structure. Figure 16: BP86/RI/TZVPP optimized Ph2Ca dimmer structure.

19 References [1] R. Ahlrichs et al., Turbomole, [2] R. Ahlrichs, M. Bär, M. Häser, H. Horn, C. Kölmel, Chem. Phys. Lett. 1989, 162, 165. [3] C. Møller, M. S. Plesset, Phys. Rev. 1934, 46, [4] A. D. Becke, Phys. Rev. A 1988, 38, [5] J. P. Perdew, Phys. Rev. B 1986, 33, [6] A. D. Becke, J. Chem. Phys. 1993, 98, [7] P. J. Stephens, F. J. Devlin, C. F. Chabalowski, M. J. Frisch, J. Phys. Chem. 1994, [8] ftp://ftp.chemie.uni-karlsruhe.de/pub/basen. [9] P. Schwerdtfeger, M. Dolg, W. Schwarz, G. Bowmaker, P. Boyd, J. Chem. Phys. 1989, 91, [10] R. S. Mulliken, J. Chem. Phys. 1955, 23, [11] A. E. Clark, E. R. Davidson, J. Chem. Phys. 2001, 115, [12] C. Herrmann, M. Reiher, B. A. Hess, J. Chem. Phys. 2005, 122, [13] J. Neugebauer, M. Reiher, C. Kind, B. A. Hess, J. Comput. Chem. 2002, 23, [14] G. Schaftenaar, [15] R. Fischer, M. Gärter, H. Görls, M. Westerhausen, Organometallics 2006, 25,