Addition of Carbon–Fluorine Bonds to a Mg(I)–Mg(I) Bond: An Equivalent of Grignard Formation in Solution

Addition of the carbon–fluorine bond of a series of perfluorinated and polyfluorinated arenes across the Mg–Mg bond of a simple coordination complex proceeds rapidly in solution. The reaction results in the formation of a new carbon–magnesium bond and a new fluorine–magnesium bond and is analogous to Grignard formation in homogeneous solution.

G e n e r a l E x p e r i m e n t a l S 3 2 S y n t h e t i c P r o c e d u r e s S 4 3 V a r i a b l e T e m p e r a t u r e 1 9 F N M R D a t a S 1 3 4 X -r a y D a t a S 1 6 5 D F T D a t a S 2 3 6 Z M a t r i c e s S 2 8 7 M u l t i n u c l e a r N M R D a t a S 5 3 S3

General Experimental
All manipulations were carried out using standard Schlenk-line and glovebox techniques under an inert atmosphere of argon or dinitogen. A MBraun Labmaster glovebox was employed, operating at < 0.1 ppm O 2 and < 0.1 ppm H 2 O.
NMR scale reaction of BDIMg-MgBDI.(THF) 2 with C 6 F 6 : BDIMg-MgBDI (10 mg, 0.011 mmol) was dissolved in benzene-d 6 (0.6 mL) and the solution transferred into a Young's tap NMR tube equipped with a capillary tube containing a ferrocene standard solution; a t=0 1 H NMR spectrum was recorded. To the solution was added a drop of tetrahydrofuran where an immediate colour change from yellow to orange was observed. A further 1 H NMR was recorded, clearly showing the formation of the THF adduct, as evidenced by the upfield shifts in the NMR signals.

Cross-over experiment to form 4
Synthesis of 4 mes BDIMg-MgBDI dipp : To a Young's tap ampoule was added mes BDIMg-MgBDI mes (73 mg, 0.1 mmol) and dipp BDIMg-MgBDI dipp (90 mg, 0.1 mmol) in toluene (5 mL). The ampoule has heated at 353 K and the reaction was monitored by taking NMR aliquots. After 10 days it was necessary to add more mes BDIMg-MgBDI mes to the reaction ( mes BDIMg-MgBDI mes has lower solution stability and degrades over time). After a total of 2 weeks at 353 K, the solution was filtered to remove a significant amount of black precipitate and the filtrate was reduced in vacuo. The yellow crystalline solid was washed with hexane (

S15
The reaction mixture from the addition of 1 to hexafluorobenzene also shows a decoalescence of the ortho-and meta- hour data collection, the data collected for the crystal of 2a was weak (overall I/σ ca. 3.1), and the presence of three differently orientated lattices in the crystal was clearly a contributing factor in this weak scattering.
The structure was found to contain two crystallographically independent complexes, 2a-A and 2a-B. The THF ligand in complex 2a-A was found to be disordered, with two orientations of ca. 77 and 23% occupancy identified for the middle two carbon atoms of the C 4 chain [C42A and C43A]. The geometries of both orientations were optimised, the thermal parameters of adjacent atoms were restrained to be similar, and only the non-hydrogen atoms of the major occupancy orientation were refined anisotropically (those of the minor occupancy orientation were refined isotropically).

The X-ray crystal structure of 2b
The C36-based CF 3 unit in the structure of 2b was found to be disordered. Two orientations were identified of ca. 80 and 20% occupancy, their geometries were optimised, the thermal parameters of adjacent atoms were restrained to be similar, and only the atoms of the major occupancy orientation were refined anisotropically (those of the minor occupancy orientation were refined isotropically).

The X-ray crystal structure of 2d
Close inspection of the diffraction data for the crystal of 2d that was studied showed a small (ca. 13%) but not insignificant twin component. Attempts to model this twinning, however, did not improve upon the results obtained without considering the twinning, and so no twin models were used in the final refinements. This unresolved twining may, however, be the root cause of some anomalous intensities.
The X-ray crystal structure of 4 The crystal of 4 that was studied was found to be a two component twin in a ca. 81:19 ratio, with the two lattices related by the approximate twin law [-1.00 0.00 -0.62 0.00 -1.00 0.00 0.00 0.00 1.00]. The complex was found to have crystallographic C 2 symmetry about an axis that passes through C2, Mg1, Mg2 and C22.
The X-ray crystal structure of [BDIMg(µ-F)(THF)] 2 The complex in the structure of [BDIMg(µ-F)(THF)] 2 was found to have crystallographic C 2h symmetry; the C 2 axis passes through the two bridging fluorine atoms F1 and F1A, whilst the mirror plane is perpendicular to this and passes through the metal centres Mg1 and Mg1A. The unique O20-based THF ligand was found to be disordered across the mirror plane, and this disorder was modelled by using one complete 50% occupancy orientation for the THF ligand (the operation of the mirror plane generates a second 50% occupancy orientation). The geometry of this unique orientation was optimised, and the non-hydrogen atoms were refined anisotropically. The C31-based included hexane solvent molecule has crystallographic C 2h symmetry.
This structure is isomorphous to the (µ-H) 2 analogue reported by Green et al. xii in 2008 (CCDC refcode XOLXEC), though that reports the unit cell using the C-face setting whereas the body-centred, I, setting is reported here. The (µ-F) 2 complex itself was reported in 2002 as a different solvate (and in a different unit cell) by Hao et al. xiii (CCDC refcode QADPOB).

Figure S8:
The structure one (2a-A) of the two independent complexes present in the crystal of 2a (50% probability ellipsoids).

Thermodynamics and Solvation: C-F Bond Cleavage Reaction
Based on the benchmarking, basis sets using an effective core potential on Mg were used in place of more costly approaches. Structures were optimised from X-ray coordinates where available separetly using the ωB97X functional with and without a dispersion correction. All mimina for both dispersion corrected and uncorrected data sets were confirmed by frequency calculations.      Figure S26: 1 H NMR spectrum of compound 2c; solvent peak marked with asterisk. Figure S27: 19 F NMR spectrum of compound 2c. 13 C{ 1 H} NMR, 100 MHz, C 6 D 6 , 298 K Figure S32: 1 H NMR spectrum of compound 2e; solvent peak marked with asterisk. Figure S33: 19 F NMR spectrum of compound 2e.  Figure S38: 1 H NMR spectrum of compound 2g; solvent peak marked with asterisk. Figure S39: 19 Figure S40: 13 C{ 1 H} NMR spectrum of compound 2g. Figure S41: 1 H NMR spectrum of compounds 2h and 2h'; solvent peak marked with asterisk.  Figure S44: 1 H NMR spectrum of compound 2i; solvent peak marked with asterisk. Figure S45: 19 F NMR spectrum of compound 2i.   Figure S46: 13 C{ 1 H} NMR spectrum of compound 2i. Figure S47: 1 H NMR spectrum of the NMR scale formation of compounds 2j, 2j' and 2a; solvent peak marked with asterisk.  Figure S50: 1 H NMR spectrum of isolated compounds 2j, 2j' and 2a; solvent peak marked with asterisk. Figure S51: 19 F NMR spectrum of isolated compounds 2j, 2j' and 2a.  Figure S52: 19 F NMR spectrum protonated 2j, 2j' and 2a. Figure S53: 1 H NMR spectrum of the NMR scale formation of compounds 2k, 2k' and 2j'; solvent peak marked with asterisk.