Mononuclear Metal-O2Complexes ~ bearing macrocyclictmc ligands~

Transcription

1 Mononuclear Metal-O2Complexes ~ bearing macrocyclictmc ligands~ Nam, Wetal. Acc.Chem. Res. Early View Sonobe (D1) 1

2 Contents 1. Introduction 2. Synthesis & Characterization 2-1. Cr-O2, Ni-O2 complexes 2-2. Mn-O2, Co-O2 complexes 2-3. Fe-O2 complex 3. Reactivity 3-1. Electrophilic oxidation 3-2. Nucleophilic oxidation 4. Summary 2

3 Introduction transformation of naturally occuring molecules oxidative metabolism of xenobiotics oxidative phosphoryration 3

4 metalloenzymes are well investigated e.g. P450 Introduction Ref) I. Schlichting et al. Science 2000, 287,

5 Introduction Naphtalene dioxygenase Ref) S. Ramaswamy et al. Science 2003, 299, model study of M-O2 We can understand the O2 activation mechanisms & apply M-O2 to organic reaction!! 5

6 Contents 1. Introduction 2. Synthesis & Characterization 2-1. Cr-O2, Ni-O2 complexes 2-2. Mn-O2, Co-O2 complexes 2-3. Fe-O2 complex 3. Reactivity 3-1. Electrophilic oxidation 3-2. Nucleophilic oxidation 4. Summary 6

7 Synthesis of Metal-Superoxoand PeroxoComplexes JACS, 2010, 132, JACS, 2006, 128, Nat. Chem. 2009, 1,

8 Cr-O2 complex 8

9 End-On Cr(III)-Superoxo Complex characterization a) UV-vis absorptionspectra & resonance Raman spectra b) ESI-MS analysis UV-vis [Cr(14-TMC)(Cl)] + [Cr(14-TMC)(O2)(Cl)] + rraman 16O2 18 O2 16 [Cr(14-TMC)( O2)(Cl)] + 18 [Cr(14-TMC)( O2)(Cl)] + O-Ostretchingvibration =66cm -1 (calculated =67cm -1 ) [Cr III (14-TMC)(O 2 )(Cl)] + :1170cm -1 PNAS. 2003, 100, reportedramanshiftofend-oncr(iii)-superoxocomplex [Cr(O 2 )(H 2 O) 5 ] 2+ =1166cm -1 reportedramanshiftofside-oncr(iii)complex [Tp tbu Cr(pz'H)(O 2 )]BARF=1072cm -1 9

10 Ni-O2complex JACS. 2006, 128, [Ni(14-TMC)](OTf) blue O 2 bubbling O 2 bubbling or H 2 O 2 (10eq.) Et 3 N(10eq.) O 2 [Ni(14 - TMC)(O 2 )] + green-brown rraman; 1131 cm-1 Ni 2+ -superoxo ESI-MS; 346.1(calcd ) O 2 XAS(X-ray absorption spectroscopy) eV->characteristicofNi 2+ Ni-O-O-Ni red DFT optimized structure EXAFS;Ni-O1.984Å->end-on H 2 O 2 (5eq.) Nat.Chem.2009,1,568. Et 3 N(2eq.) Ni(ClO 4 ) 2..6H 2 O + 12-TMC [Ni(12 - TMC)(CH 3 CN)] 2+ (1.2 eq.) (1.0eq.) MeCN, reflux purple solid MeCN,0 o C Me Me distorted octahedral geometry N N ( O-Ni-O=43.04 o ) O-O bond length; 1.386(4) Å Ni-O bond length; Å N N thiscomplexpersistseveraldaysat25 o C!! Me Me 12-TMC X-ray [Ni(12 - TMC)(O 2 )] 2+ green solid 10

11 side-on Ni(12-TMC)-O2 complexes characterization 11

12 DFT calulation of Ni(nTMC)-O2 complexes 12

13 Synthesis of Metal-Superoxoand PeroxoComplexes Co complex: Inorg. Chem. 2008, 102, JACS, 2010, 132, Mn complex: ACIE, 2007, 46, 377. ACIE, 2009, 48,

14 Side-On Mn(III)-peroxo Complex synthesis & characterization (Mn(14-TMC)(O2)-complex MnCl 2 +TMS(CF 3 SO 3 ) 2. 2CH 3 CN CH 3 CN inglovebox 14-TMC(1.0 eq.) Mn(CF 3 SO 3 ). 2 2CH 3 CN CH 3 CN (1.2eq.) H 2 O 2 (5.0eq.) Et 3 N(2.5eq.) CH 3 CN,rt 30sec Mn(14-TMC)(CF 3 SO 3 ) 2. 2CH 3 CN 70% yield. [Mn(14-TMC)(O 2 )] + This complex persisted several 25 oc! 14

15 Side-On Mn(III)-peroxido Complex synthesis & characterization (Mn(14-TMC)(O2)-complex EPR analysis [Mn(tmc)] 2+ [Mn(tmc)(O2)] + g= 2.0 EPR silent!! (S= 5/2) Mn(II) species d 4species; high-spin (S=2) or low-spin (S=1)?? determination of spin state by HNMR spectroscopic method (Evans method; J. Chem. Soc. 1959, 2003.; J. Chem. Soc. Dalton Trans. 1998, 2927.) 5.4µB high spin state 15

16 Side-On Mn(III)-peroxido Complex synthesis & characterization (Mn(13-TMC)(O2)-complex) 16

17 Co(OTf) 2. 6H 2 O + 14-TMC CH3 CN,Ar Side-On Co(III)-peroxo Complex synthesis & characterization UV-vis comparabletothereportedside-onco III N 4 O 2 max=436nm Inorg. Chem. 2004, 43, nm 801nm EPR&NMR H 2 O 2 (5eq.) Et Co II (TMC)(CH 3 CN) 2+ 3 N(2.5eq.) [Co III (TMC)(O 2 )] + CH 3 CN,0 o C peroxo complex ESI-MS [Co(14-TMC)( 16 O 2 )] + ;m/z=347.1 [Co(14-TMC)( 18 O 2 )] + ;m/z=351.1 Co(TMC)(CH 3 CN) 2+ ;g=7.13,2.15,1.51 typicalhighspin(s=3/2)co II (d 7 ) [Co III (TMC)(O + highspin(s=2)or(s=0)co III 2 )] ;EPRsilent!! (d 6 ) Inorg. Chem. 2008, 102, JACS, 2010, 132, H 2 O 2 (5eq.) Co(ClO 4 ). 2 6H 2 O+12/13-TMC CH3 CN,Ar CoII (TMC)(CH 3 CN) 2+ Et 3 N(2.5eq.) [Co III (TMC)(O 2 )] + CH 3 CN,0 o C peroxo complex O-O length; 1.438(9) Å(12-TMC) 1.438(4) Å(13-TMC) Co-O length; Å Å 14-TMC-Ni-peoxo;1.386 Å 12/13-TMC-Co; Å 12-TMC 13-TMC 12-TMC-Co; Å CoO 2 angle;45.36 o o 17

18 XAS analysis Side-On Co(III)-peroxo Complex synthesis & characterization rising-edge 7721 ev ev > pre-edge( ev) reflects ligand-field strength > rising-edge(7721 ev) reflects the charge at the absorbing metal center->typicalenergyforco 3+ >EXAFS paremeterofbothofthecomplexesarein good agreement with the crystal structure. UV-vis [Co(12-TMC)(O 2 )] + 2 max=350nm 560nm shouldersat~500,~700 nm [Co(13-TMC)(O 2 )] + max=348nm 562nm shouldersat~500,~710 nm rraman(442 nm) ;24cm -1 =Co-O ESI-MS [Co(12-TMC)( 16 O 2)] + ;319.1(calcd319.2) [Co(12-TMC)( 18 O 2 )] + ;323.1(calcd323.2) [Co(13-TMC)( 16 O 2 )] + ;333.1(calcd333.2) [Co(13-TMC)( 18 O 2 )] + ;337.1(calcd337.3) Co(III)-O2 complexes exist as superoxo complexes in solid & solution state ;22cm -1 =Co-O 16 O 2 18 O ; 57cm -1 =O-O ; 56cm -1 =O-O [Co(12-TMC)(O 2 )] + [Co(13-TMC)(O 2 )] + 18

19 XAS ev Co-(14-TMC)(O2) is really side-on?? DFT calculation [Co(12-TMC)(O2)] ev [Co(12-TMC)(O2)] + [Co(12-TMC)(CH3CN)] ev ev [Co(14-TMC)(O2)] + [ Co(14-TMC)(CH3CN)] 2+ [Co(14-TMC)(O2)] 14-TMC and 12-TMC complexes show Co ev 14-TMC and 12-TMC complexes are side-on DFT calculation 11.5 kcal/mol higher ev + [Ni(14-TMC)(O2)] [Ni(12-TMC)(O2)] + Ni Ni

20 Synthesis of Metal-Superoxoand PeroxoComplexes Fe complex: Science 2003, 299, Chem. Commun., 2005, JACS, 2010, 132, Nature 2011, 478,

21 Fe=O Complex syntheis& charactrization Science 2003, 299, X-ray UV-vis; λmax= 820 nm ESI-MS; obs476.9 [Fe(IV)(O)(14-TMC)(OTf)] + rraman; [Fe(III)O(L)] 2+ O2: 834 cm-1 O2: 800 cm

22 Fe=O & Fe-O2 Complexes syntheis& charactrization Chem. Commun., 2005, UV-vis; 750 nm ESI-MS; found calculated O-labeled complex; X-band EPR; typical of a high-spin (S=5/2) Fe(III) species 22

23 Fe=O & Fe-O2 Complexes syntheis& charactrization(dioxygenactivation) JACS, 2005, 127, JACS, 2009, 131,

24 Fe=O & Fe-O2 Complexes syntheis& charactrization JACS, 2010, 132, KIE value;

25 Fe=O & Fe-O2 Complexes syntheis& charactrization Nature2011, 478, 502. Et 3 N(2.0eq.) Fe(TMC)(OTf) 2 + H 2 O 2 (5.0eq.) CF 3 CH 2 OH,0 o C first report of Fe(III) peroxo structure bond length Uv-vis(stopped-flow) O-O;1.463(6)Å Fe-O;1.910Å longer than those of (TMC)-Fe-peroxo complexes. geometry alln-megroupspointto thesamesideoftheperoxo moiety, as observed in otherm III -peroxocomplexes. Noaxialligandbindsto Fetranstotheperoxoligand. [Fe(TMC)(O 2 )] + UV-vis (L)Fe III OOH t 1 / 2 =60min (L)Fe III O O (L)Fe IV O (L)Fe III OOH (L)Fe III O O 782 nm immediately dissapeared but 526 nm gradualy appeared. 25

26 EPR Fe=O & Fe-O2 Complexes charactrization of Fe-OOH first shell EXAFS g=6.8,5.2,1.96 Fe K pre-edge energy and intensity fit values 16 O 18 O Fe-O O-O Raman spectrum O-Ostretch( max =868cm -1 )oftmc-fe-oohishigherthanother high-spinfe III -OOH(R)complexesandmuchhigherthanlow-spin Fe III -OOHcomplexes. cf)high-spincomplex:[fe(h 2 bppa)(ooh)] 2+ ( max =830cm -1 ) Inorg. Chem. 2002, 41, 616. low-spincomplex:[fe(n4py)(ooh)] 2+ ( max =790cm -1 ) JACS. 2002, 124, Fe-Ostretch( max =658cm -1 )ishigher O OH than six-cordinate high-spin complex N N ( max =621cm -1 ),indicatingtheabsence Fe of trans-axial ligand. N N high-spin(s=5/2) Fe III species 26

27 Fe=O & Fe-O2 Complexes formong Fe(IV)=O from Fe-OOH If Fe(IV)=O were in fact product of 1ereduction of Fe(V)=O, the amount of Fe(IV)=O was decrease due to the fast reaction between the highly reactive Fe(V)=O and the substrates. 27

28 3. Reactivity 28

29 Electrophilic Reaction with Cr-superoxo/C-H activation JACS, 2010, 132,

30 t Bu N N O OH Cr III O N t Bu N substrates Electrophilic Reaction with Cr-superoxo/O-H activation N t Bu N OH Cr III N Chem. Sci. 2011, 2, N Cr-O 2 ;pseudo-firstorderdecay&itsconctantswasdependenton O [substrate]. second-order rate constants were determined. t Bu (k 2 =4.7x10-1`-40 o C) O 30

31 N N O O Ni II N N Electrophilic Reaction with Ni(14-TMC)-O2 N N OH Ni II N N JACS, 2006, 128, PPh 3 Ph 3 P O whenni- 18 O 2 wasused, 18 O=PPh 3 wasobtained. DFT calculation sourceofoisni-o 2 Chem. Commun. 2011, 47, second-order rate constant k=6.5x10-3 M -1 s -1 at0 o C Eyring analysis Ni-peroxocomplexcanoxidazePPh 3,XA,CHD. H =6.8kcal/mol S =-44calmol -1 K -1 G =18.8kcal 31

32 O2 transfer reaction with Ni(12-TMC)-O2 Nat. Chem. 2009, 1, 568. Mn-O2 Ni-O2 spectral evidence for an intermolecular O 2 transferfromn-o 2 tomn. 32

33 3. Reactivity 33

34 Deformylation (oxidative nucleophilic addition) Me Me H O Y 2-PPA O Y 2-PPA Hammet plot; 2-PPA =

35 Deformylation axial ligand effect 35

36 Deformylation axial ligand effect 36

37 Deformylation axial ligand effect 37

38 Summary M-O2 complexes have been synthesized & characterized. The coordination mode of O2are affected by some factors. (e.g. ring size of ligand; Ni, ph; Fe-O2) M-O2 reactivity end-on complexes -> electrophilic oxidation side-on complexes -> nucleophilic oxidation catalytic reaction side-on Fe-O2 (TON~3) nucleophilicity is also affected by ring size & axial ligand 38

39 Summary of M-O2 & its physical properties 39