Palladium(II) Complexes of 1,2,4-Triazole Based

Transcription

1 Supporting Information Palladium(II) Complexes of 1,2,4-Triazole Based N-Heterocyclic Carbenes: Synthesis, Structure and Catalytic Activity. Jan Turek [a], Illia Panov [b], Miloslav Semler [c], Petr Štěpnička [c], Frank De Proft [d], Zdeňka Padělková [a], Aleš Růžička* [a] [a] Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, CZ , Pardubice, Czech Republic. [b] Institute of Organic Chemistry and Technolgy, Faculty of Chemical Technology, University [c] Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030, Prague, Czech Republic. [d] Eenheid Algemene Chemie (ALGC), Member of the QCMM VUB-UGent Alliance Research Group, Vrije Universiteit Brussel, Pleinlaan 2, Brussels, Belgium. *Fax: Contents Figure S1 S2 Table S1 S3 Scheme S1 S3 Crystallographic parameters S4 Theoretical calculations NOCV analysis S6 1 H and 13 C{ 1 H} NMR spectra of all Pd complexes S9 S1

2 Figure S1. The molecular structure (ORTEP 30% probability level) of 4b. Hydrogen atoms are omitted for clarity. Selected interatomic distances [Å] and angles [ ]: Pd1-C (10), Pd1-O2A 2.01(3), N1-C (16), N3-C (18), O2A-Pd1-C1 87.9(10) [92.1(10)], N1- C1-Pd (9), N3-C1-Pd (9), N1-C1-N (10). S2

3 Table S1. Summary of catalytic results obtained with different bases in the coupling reaction of 4-bromotoluene with phenylboronic acid in the presence of 4a (0.5 mol.-%) in ethanol at 25 C. Base Yield [%] Base Yield [%] Li 2 CO 3 4 NaF 2 Na 2 CO 3 14 NaOAc anhyd. b 8 K 2 CO 3 38 Na 3 PO 4 23 Rb 2 CO 3 50 Na 2 HPO 4. 12H 2 O 3 Cs 2 CO 3 63 NaH 2 PO 4 H 2 O 2 a Conditions: 4-bromotoluene (1.0 mmol), phenylboronic acid (1.2 mmol), base (1.2 mmol) and 0.5 mol.% of 4a. The reaction was performed in azeotropic ethanol (5 ml) at 25 C for 1 h. b Reaction performed in the presence of NaOAc 3H 2 O gave the coupling product in a 4% yield. Scheme S1. Sequential Suzuki-Miyaura cross-coupling reaction of 1,4-dibromobenzene with (4-acetylphenyl)boronic acid and 4-tolueneboronic acid in the presence of 4a (0.5 mol.-%). S3

4 Table S2. Crystallographic data for 4a, 4a, 4b, 4b, 4c and 4c Compound 4a 4a 4b 2CHCl 3 chem formula C 21 H 26 Cl 2 N 4 Pd C 25 H 34 N 4 O 5 Pd C 38 H 42 Cl2N 6 O 2 Pd 2CHCl 3 cryst syst orthorhombic monoclinic monoclinic space group P P 2 1 /c P 2 1 /c a/å (8) (11) (9) b/å (9) (2) (12) c/å (10) (12) (10) α/deg β/deg (6) (6) γ/deg Z unit cell volume/å (3) (5) (3) density/g.cm abs coeff, µ/mm F(000) h; k; l min, max -12, 11; -17, 19; -16, 15; -22, 22; -13, 16; -17, 21; -17, 19-15, 15-13, 15 θ min; max /deg 1.92; ; ; reflections total (R int ) a 4973 (0.0314) 5223 (0.0714) 5016 (0.0389) observed [I>2σ(I)] no. of parameters max/min τ/eå ; ; ; goodness of fit on F 2b final R1 values (I>2σ(I)) c final wr2 values (I>2σ(I)) S4

5 Table S2 continued Compound 4b 4c 2CHCl 3 4c chem formula C 42 H 48 N 6 O 6 Pd C 38 H 42 Cl 2 N 6 Pd 2CHCl 3 C 42 H 48 N 6 O 4 Pd cryst syst triclinic orthorhombic monoclinic space group P -1 Pbca C2 a/å (7) (8) (10) b/å (6) (3) (7) c/å (6) (3) (10) α/deg (4) β/deg (4) (5) γ/deg (4) Z unit cell volume/å (11) (14) (3) density/g.cm abs coeff, µ/mm F(000) h; k; l min, max -11, 11; -12, 12; -12, 9; -35, 30; -23, 23; -12, 12; -15, 15-35, 39-12, 13 θ min; max /deg 4.20; ; ; reflections total (R int ) a 3026 (0.0625) 8804 (0.0753) 3466 (0.0327) observed [I>2σ(I)] no. of parameters max/min τ/e Å ; ; ; goodness of fit on F 2b final R1 values (I>2σ(I)) c final wr2 values (I>2σ(I)) a R int = F o 2 - F o,mean 2 / F o 2. b S = [ (w(f o 2 - F c 2 ) 2 ) / (N diffr. - N param. )] ½. c Weighting scheme : w = [σ 2 (F o 2 ) + (w 1 P) 2 + w 2 P] -1, where P = [max(f o 2 ) + 2F c 2 ], R(F) = F o - F c / F o, wr(f 2 ) = [ (w(f o 2 - F c 2 ) 2 ) / ( w(f o 2 ) 2 )] ½ S5

6 Natural orbitals for chemical valence (NOCV) analysis. Figure S3. Relevant NOCV pairs with the corresponding density change, numbers of electrons transferred and contribution to the total orbital interaction energy component of the binding energy for the monocarbene complexes ( O NHC = 2-methoxyphenyl substituted carbene; N NHC = 2-((dimethylamino)methyl)phenyl substituted carbene). As mentioned in the main text, in the case of monocarbene complexes, three relevant NOCV pairs can be identified for the formation of the metal complex from the carbene and palladium chloride fragments. In the dominant NOCV, the density depletion (red)/accumulation (blue) pattern describes the strong σ-donation of the NHC ligand to the metal with minor contribution of the donation from the N/O donor atom. The density rearrangement represented by the NOCV-2 pair describes the expected weak π-backdonation from the Pd metal to the carbene. Finally, the last NOCV-3 pair reflects the stabilizing effect of the extra donating group. The differences in the two complexes with different donors in Figure S3 are in a good agreement with the experimental results, where the monocarbene complex is formed only in the case of the 2-[(dimethylamino)methyl]phenyl substituted carbene. The NOCV-2 pairs are of the same magnitude of the density change and associated energy in both complexes, S6

7 whereas the stabilizing effect of the amino donating group, represented by the NOCV-3 pair and partially by the NOCV-1 pair, is significantly more important than the effect of the methoxy group. Figure S4. Relevant NOCV pairs with the corresponding density change, numbers of electrons transferred and contribution to the total orbital interaction energy component of the binding energy for the biscarbene complexes ( O NHC = 2-methoxyphenyl substituted carbene; N NHC = 2-((dimethylamino)methyl)phenyl substituted carbene). For the biscarbene complexes (Figure S4) only two relevant NOCV pairs were found, which was expected since the intramolecular donation of the nitrogen/oxygen atom to the metal is no longer possible. Both pairs describe, similarly as in the case of monocarbene complexes, σ-donation of the NHC (NOCV-1) and the weak π-backdonation from the metal (NOCV-2). The differences in density change and the associated energy for the two examined complexes are negligible. This is again caused by the formation of the biscarbene complex whose structure is very similar for both complexes with an insignificant influence of the donating group turned away from the coordination sphere of the palladium atom. S7

8 The last set of investigated compounds are the PEPPSI TM type complexes with various NHC ligands going from the well known Arduengo-type carbenes to the less typical CAAC and mesoionic carbenes (Figure S5). There are again, as expected, two relevant NOCV pairs with a pattern similar to the NOCVs described in the first part of this study. According to the NOCV analysis of the set of six different types of carbene ligands, a magnitude of the stabilization energy of each NHC was determined. In line with Figure S5, the stabilizing effect of the carbene ligand increases in the series: tetrazol-based carbene, triazol-based carbene, unsaturated Arduengo-type carbene, saturated Arduengo type carbene, mesoionictype carbene and CAAC (cyclic alkyl amino carbene). Figure S5. Relevant NOCV pairs with the corresponding density change, numbers of electrons transferred and contribution to the total orbital interaction energy component of the binding energy in the PEPPSI TM type complexes. (A = unsaturated Arduengo-type carbene; B = saturated Arduengo type carbene; C = triazol-based carbene; D = tetrazol-based carbene; E = CAAC (cyclic alkyl amino carbene); F = mesoionic-type carbene) S8

9 1 H and 13 C{ 1 H} NMR spectra of all Pd complexes Figure S6. 1 H NMR of 4a Figure S7. 13 C{ 1 H} NMR of 4a S9

10 Figure S8. 1 H NMR of 4a Figure S9. 13 C{ 1 H} NMR of 4a S10

11 Figure S10. 1 H NMR of 4b (Please note: The relative integral intensity of the major aromatic multiplet is hampered by the signal of CDCl 3 ) Figure S C{ 1 H} NMR of 4b S11

12 Figure S12. 1 H NMR (CDCl 3, 20 C) of 4b after heating at 40 C for 24 hours in CDCl 3 Figure S C{ 1 H} NMR (CDCl 3, 18 C) of 4b after heating at 40 C for 24 hours in CDCl 3 S12

13 Figure S14. 1 H NMR of 4b (Please note: The relative integral intensity of the major aromatic multiplet is hampered by the signal of CDCl 3 ) Figure S C{ 1 H} APT NMR of 4b S13

14 Figure S16. 1 H NMR of 4c Figure S C{ 1 H} APT NMR of 4c S14

15 Figure S18. 1 H NMR of 4c Figure S C{ 1 H} APT NMR (CDCl 3, 23 C) of 4c S15