1

Supporting Information

For

Ligand-Centered Reactivity of a Pseudo-Dearomatized Phosphorus-

Nitrogen PN3P* Rhodium Complex towards Molecular Oxygen at

Room Temperature

Chunhui Zhou,‡ Kristin Munkerup,‡ Yuan Wang, Pradip K. Das, Priyanka Chakraborty, Jinsong

Hu, Changguang Yao, Mei-Hui Huang and Kuo-Wei Huang*

KAUST Catalysis Center and Division of Physical Sciences and Engineering, King Abdullah

University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.

*E-mail: hkw@kaust.edu.sa

Electronic Supplementary Material (ESI) for Inorganic Chemistry Frontiers.This journal is © the Partner Organisations 2020

2

Table of Contents

Figure S1 1H NMR spectrum of 2 (400 MHz, C6D6) ....................................................................................... 6

Figure S2 31P{1H} NMR spectrum of 2 (202 MHz, C6D6) .............................................................................. 6

Figure S3 13C NMR spectrum of 2 (101 MHz, C6D6) ..................................................................................... 7

Figure S4 1H NMR spectrum of 3 (400 MHz, C6D6) ...................................................................................... 7

Figure S5 31P{1H} NMR spectrum of 3 (162 MHz, C6D6) .............................................................................. 8

Figure S6 13C NMR spectrum of 3 (101 MHz, C6D6) ..................................................................................... 8

Figure S7 1H NMR spectrum of 5 (400 MHz, THF-d8)................................................................................... 9

Figure S8 31P{1H} NMR spectrum of 5 (162 MHz, THF-d8) .......................................................................... 9

Figure S9 13C NMR spectrum of 5 (101 MHz, THF-d8)................................................................................ 10

Figure S10 1H NMR spectrum of 6 (400 MHz, C6D6) .................................................................................. 10

Figure S11 31P{1H} NMR spectrum of 6 (162 MHz, C6D6) .......................................................................... 11

Figure S12 13C NMR spectrum of 6 (101 MHz, C6D6) ................................................................................. 11

Figure S13 CV data of 1 ............................................................................................................................. 12

Figure S14 Molecular structure of 4.. ........................................................................................................... 12

Table 1 crystal data and structure refinements for 2-4 ................................................................................... 13

Table 2 crystal data and structure refinements for 5 and 6............................................................................. 14

3

Experimental Details

General considerations: All reactions with various metal complexes were carried out under an

atmosphere of dry argon in a glovebox or using Schlenk techniques to ensure oxygen and external

water free environments, unless noted otherwise. All glassware was rigorously dried. All solvents

were distilled from sodium benzophenone ketyl prior to use, unless noted otherwise. All other

chemicals were commercially available and used as received. O2 gas (99.999%) was purchased

from commercial sources in high pressure cylinder and used without further purification using

Schlenk techniques. 1 was prepared according to the literature procedure (ref. 8a). NMR spectra

were recorded at 400 MHz (1H), 101 MHz (13C), and 162 MHz (31P) using a Bruker Avance-400

NMR spectrometer, unless noted otherwise. All spectra were recorded at 25 oC, and δ values were

denoted by ppm and J by Hz. All chemical shifts were reported with references to the residual

solvent resonance of the deuterated solvents for proton and carbon shifts, and to external H3PO4

(85%) for phosphorus chemical shifts. The HRMS data were obtained using a Finnigan MAT 95

system. Elemental analyses were carried out on a Flash 2000 elemental analyzer.

Synthesis of 2, 3 and 4. A solution of 1 (0.6 mmol, 316 mg in THF) was put in a 100 mL Schlenk

flask. The flask was connected to a Schlenk line and then degassed and saturated with O2 three

times. The resulting mixture was stirred overnight at room temperature, and the color of the

solution changed to red-brown and the reaction was completed, filtered and the solvent was

removed in vacuo, 2 (129 mg, 40 %) and 3 (6 mg, 2%) were isolated separately by flash

chromatography on silica gel eluting with petroleum ether/ ethyl acetate (3/1-3/1), and trace

amount of 4 was obtained only confirmed by single crystal structure analysis. Crystals of 2, 3 and

4 suitable for single X-ray structure determination were obtained by slow evaporation of its

benzene solution. For 2, 1H NMR (400 MHz, C6D6): 6.91 (d, 3JHH = 9.9 Hz, 1H, -CH=CH-CO-),

6.10 (m, 1H, -CH=CH-CO-), 1.29 (m, 36H, -PC(CH3)3). 31P{1H} NMR (202 MHz, C6D6): 140.8

(dd (AB), 2JPP = 252.5 Hz, 1JRhP = 127.3 Hz, 1P), 138.74 (dd (AB), 2JPP = 252.5 Hz, 1JRhP = 127.3

Hz, 1P). 13C NMR (101 MHz, C6D6): 199.80 (dt, 2JPC = 10.8 Hz, 1JRhC = 68.6 Hz, RhCO), 176.36-

176.57 (m, -CH=CH-CO-), 165.60-165.75 (m, -N=C-), 161.72 (m,-N=C-), 137.72-137.93 (m, -

CH=CH-CO-), 134.58 (m, -CH=CH-CO-), 37.71-38.16 (m, -PC(CH3)3), 28.51-28.55 (m, -

PC(CH3)3). HRMS (ESI) Calcd. for C22H38N3O2P2Rh requires (M+H)+: 542.1540, Found:

542.1567. Anal. Calcd. for C22H38N3O2P2Rh: C, 48.81; H, 7.07; N, 7.76. Found: C, 48.96; H, 7.13;

4

N, 7.64. For 3, 1H NMR (400 MHz, C6D6): 6.50 (m, 1H, -C=CH-CO-), 1.29(d, J = 12.9 Hz, 18H,

-PC(CH3)3), 1.16(d, J = 12.8 Hz 18H, -PC(CH3)3). 31P{1H} NMR (162 MHz, C6D6): 141.4 (dd

(AB), 2Jpp = 253.2 Hz, 1JRhP = 127.3 Hz, 1P), 138.7 (dd (AB), 2Jpp = 253.2 Hz, 1JRhP = 127.3 Hz,

1P). 13C NMR (101 MHz, C6D6): 199.44 (dt, 2JPC = 10.8 Hz, 1JRhC = 69.9 Hz, RhCO), 177.16 (d, -

C=CH-CO-), 164.54 (m, -N=C-), 161.68 (m, -N=C-), 144.65 (d, -C=CH-CO-), 134.35 (m, -C=CH-

CO-), 37.86-38.20 (m, -PC(CH3)3), 28.40-28.53 (m, -PC(CH3)3). HRMS (ESI) Calcd. for

C44H74N6O4P4Rh2 requires (M+H)+ : 1081.2915, Found: 1081.2916.

Synthesis of 5. A dry benzene solution (5 mL) of thiophenol (22.0 mg, 0.20 mmol) was added to

a stirred light brown benzene suspension of (3 mL) of 2 (108.2 mg, 0.20 mmol) under air. The

resulting suspension was stirred overnight at room temperature, then the solvent was removed

under vacuum, then target product (123 mg, 95%) was purified by flash chromatography on silica

gel eluting with petroleum ether/ ethyl acetate (15/1-5/1). Crystals of 5 suitable for single X-ray

structure determination were obtained by slow evaporation of its benzene solution. 1H NMR (400

MHz, THF-d8): 7.57-7.60 (m, 2H, Ph(H)S-), 7.52 (m, 2H, Ph(H)S-), 7.51 (s, 1H, Ph(H)S-), 5.72

(br, 1H, -PhSC=CH-CO-), 1.36-1.39 (m, 18H, -PC(CH3)3), 1.29-1.33 (m, 18H, -PC(CH3)3). 31P{1H}

NMR (162 MHz, THF-d8): 138.7 (dd (AB), 2JPP = 252.7 Hz, 1JRhP = 128.0 Hz, 1P) and 137.0 (dd

(AB), 2JPP = 252.7 Hz, 1JRhP = 128.0 Hz,1P). 13C NMR (101 MHz, THF-d8): 199.82 (dt, 2JPC =

11.0 Hz, 1JRhC = 69.4 Hz, RhCO), 174.08-174.27 (m, -CS=CH-CO-), 163.77-163.94 (m, -N=C-),

162.12-162.18 (m, -N=C-), 156.63-156.81 (m, -CS=CH-CO-), 136.32 (s, Ph(C)), 131.13 (s, Ph(C)),

131.02 (s, Ph(C)), 130.71 (s, Ph(C)), 125.75 (s, -CS=CH-CO-), 38.37-38.79 (m, -PC(CH3)3), 28.74

(s, -PC(CH3)3). HRMS (APCI) Calcd. for C28H42N3O2P2RhS requires (M+H)+: 650.1601, Found:

650.1595. Anal. Calcd. for C28H42N3O2P2RhS: C, 51.77; H, 6.52; N, 6.47. Found: C, 52.03; H,

6.62; N, 6.28.

Synthesis of 6. A dry THF solution (5 mL) of 4-methylaniline (21.4 mg, 0.20 mmol) was added

to a stirred light brown THF suspension of (3 mL) of 2 (108.2 mg, 0.20 mmol). The resulting

mixture was stirred 24 hours at 60 oC, and the color of the solution changed to dark red and the

reaction was completed, filtered and the solvent was removed in vacuo, then target product (6, 78

mg, 60 %) was purified by flash chromatography on silica gel eluting with petroleum ether/ ethyl

acetate (6/1-3/1). Crystals of 6 suitable for single X-ray structure determination were obtained by

slow evaporation of its toluene solution in the low temperature. 1H NMR (400 MHz, C6D6): 8.28

5

(s, 1H, -CH3PhNHC=CH-CO-), 6.76 (s, 4H, -CH3Ph(H)NHC=CH-CO-), 6.38 (br, 1H, -

CH3PhNHC=CH-CO-), 2.01 (s, 3H, -CH3Ph(H)NHC=CH-CO-), 1.34 (d, 3JHP = 14.0 Hz, 18H, -

PC(CH3)3), 1.25 (d, 3JHP = 13.9 Hz, 18H, -PC(CH3)3). 31P{1H} NMR (162 MHz, C6D6): 141.8 (dd

(AB), 2JPP = 254.2 Hz, 1JRhP = 127.3 Hz, 1P), 135.6 (dd (AB), 2JPP = 254.2 Hz, 1JRhP = 127.7 Hz,

1P). 13C NMR (101 MHz, C6D6): 199.66 (dt, 2JPC = 12.7 Hz, 1JRhC = 72.5 Hz, RhCO), 176.63 (d, -

CN=CH-CO-), 163.91-164.04 (m, -N=C-), 162.97-163.06 (m, -N=C-), 145.55 (d, -CN=CH-CO-),

135.80 (s, Ph(C)), 135.05 (s, Ph(C)), 130.31 (s, Ph(C)), 122.94 (s, Ph(C)), 102.57 (s, -CN=CH-

CO-), 37.75-38.10 (m, -PC(CH3)3), 28.48-28.63 (m, -PC(CH3)3), 20.85 (s, CH3PhNH-). HRMS

(ESI) Calcd. for C29H45N4O2P2Rh requires (M+H)+: 647.2146, Found: 647.2164. Anal. Calcd. for

C29H45N4O2P2Rh: C, 53.87; H, 7.02; N, 8.67. Found: C, 54.49; H, 7.15; N, 8.53.

Single X-ray structure determination

The X-ray diffraction data of 2-6 were collected at the low temperature using Bruker D8 venture

machine with graphite-monochromated Cu-Kα radiation (λ= 1.54178 Å) or Mo-Kα (λ= 0.71073

Å), and the tested crystals were epoxy-coated and mounted on the glass fiber. The structures of

these metal complexes are solved by direct methods, for the non-hydrogen atoms, we used the trial

structure for the locating and then they were refined anisotropically with the SHELXTL using a

full-matrix least-squares procedure based on F2 values. As to the hydrogen atoms, the positions

were fixed geometrically at calculated distances and allowed to ride on the parent atoms. A semi-

empirical absorption correction was applied using the SADABS program. The detail of the crystal

data and structure refinements for complexes 2-6 are listed in Table S1 and Table S2, respectively.

6

Figure S1. 1H NMR spectrum of 2 (400 MHz, C6D6)

Figure S2. 31P{1H} NMR spectrum of 2 (202 MHz, C6D6)

7

Figure S3. 13C NMR spectrum of 2 (101 MHz, C6D6)

Figure S4. 1H NMR spectrum of 3 (400 MHz, C6D6)

8

Figure S5. 31P{1H} NMR spectrum of 3 (162 MHz, C6D6)

Figure S6. 13C NMR spectrum of 3 (101 MHz, C6D6)

9

Figure S7. 1H NMR spectrum of 5 (400 MHz, THF-d8)

Figure S8. 31P{1H} NMR spectrum of 5 (162 MHz, THF-d8)

10

Figure S9. 13C NMR spectrum of 5 (101 MHz, THF-d8)

Figure S10. 1H NMR spectrum of 6 (400 MHz, C6D6)

11

Figure S11. 31P{1H} NMR spectrum of 6 (162 MHz, C6D6)

Figure S12. 13C NMR spectrum of 6 (101 MHz, C6D6)

12

Figure S13. (A) CV data of compound 1 at different scan rate in THF (1.0 mM of complex 1,

Glassy carbon electrode [GC, diameter 3 mm] as a working electrode, Pt-wire as a counter

electrode, Ag/AgCl/1M KCl as a reference electrode, 0.1 M nBu4NPF6 as a supporting electrolyte;

(B) linear correlation between ipc (µA) of L/L+. and square root of different scan rate; (C) linear

correlation between ipa (µA) of RhIII/II and square root of different scan rate.

Figure S14. Molecular structure of 4. Thermal ellipsoids are shown at the 50% probability level;

hydrogen atoms are omitted except the OOH moiety for clarity. Selected bond lengths [Å] and

bond angles [°]:C3-O2, 1.210(7); C5-C4, 1.352(9); C5-O3, 1.333(7); C6-O1, 1.153(7); C1-N1,

1.277(7); C2-N3, 1.281(7); Rh1-N2, 2.052(4); Rh1-C6, 1.823(6); Rh1-P3, 2.2807(14); Rh1-P2,

2.2905(14), P3-Rh1-P2, 159.19(5); N2-Rh1-C6, 179.6(2); P3-Rh1-C6, 99.71(18); C6-Rh1-P2,

100.92(18); P2-Rh1-N2, 79.25(12); N2-Rh1-P3, 80.14(12).

-8

-3

2

7

-1.5 -1 -0.5 0 0.5

scan rate dependent

50 mV 60 mV70 mV 80 mV90 mV

Potential (V vs Ag/AgCl)

i (µ

A)

A

R² = 0.9913

5

5.5

6

6.5

7

0.2 0.25 0.3

at the L/L+.

ipc

(µA

)

ν1/2

A B

R² = 0.9917

2

2.5

3

3.5

4

4.5

0.2 0.25 0.3 0.35

at the RhIII/II

ν1/2

ipa

(µA

)

C

13

Table 1 crystal data and structure refinements for 2-4

identification code 2 3 4

empirical formula C22H38N3O2P2Rh C44H74N6O4P4Rh2 C22H38N3O4P2Rh

formula weight 541.40 1080.79 573.40

temperature (K) 200 150 150

wavelength (Å) 1.54178 0.71073 1.54178

crystal system Monoclinic Triclinic Monoclinic

space group P21/c P-1 P21/c

a (Å) 15.9777(7) 10.812(6) 14.8613(5)

b (Å) 10.8470(5) 16.839(11) 8.3029(3)

c (Å) 16.3690(7) 17.119(12) 22.7052(9)

α (deg) 90 117.98(3) 90

β (deg) 109.0770(10) 100.64(3) 97.156(2)

γ (deg) 90 96.97(3) 90

Z 4 2 4

V (Å3) 2681.1(2) 2626(3) 2779.81(18)

Dcalcd (g cm-3) 1.341 1.367 1.370

μ (mm-1) 6.444 0.793 6.302

F (000) 1128 1124 1192

theta min-max (deg) 2.926, 76.979 1.974, 25.473 2.997, 66.496

total uniq. Data 44441, 5217 30148, 9633 29783, 4775

R(int) 0.0298 0.1258 0.0746

observed data [I > 2σ(I)] 5166 6962 3874

R1, wR2 [I > 2σ(I)] 0.0280, 0.0861 0.1719, 0.3405 0.0449, 0.1379

S 1.087 2.715 1.149

R1 = Σ||Fo| − |Fc||/|Σ|Fo|. wR2 = {Σ[w(Fo2 − Fc

2 )2]/Σ[w(Fo2)2 ]}1/2, where w = 1/[σ2(Fo

2)+(aP)2 +

bP], P = (Fo2 + 2Fc

2 )/3

14

Table 2 crystal data and structure refinements for 5 and 6

identification code 5 6

empirical formula C28H42N3O2P2RhS C29H45N4O2P2Rh

formula weight

temperature (K)

wavelength (Å)

649.55

100

1.54178

646.54

150

1.54178

crystal system

space group

a (Å)

Monoclinic

P21/c

8.1400(6)

Monoclinic

Cc

8.0554(3)

b (Å)

c (Å)

33.950(2)

11.6847(11)

26.6716(8)

15.1151(4)

α (deg) 90 90

β (deg) 108.733(2) 104.449(2)

γ (deg) 90 90

Z 4 4

V (Å3) 3058.1(4) 3144.77(17)

Dcalcd (g cm-3) 1.411 1.366

μ (mm-1) 6.370 5.596

F (000) 1352 1352

theta min-max (deg) 2.603, 72.375 3.314, 66.701

total uniq. Data

R(int)

98988, 6008

0.0420

14996, 4889

0.0357

observed data [I > 2σ(I)] 5986 4711

R1, wR2 [I > 2σ(I)]

S

0.0291, 0.1009

1.229

0.0285, 0.0704

1.090

R1 = Σ||Fo| − |Fc||/|Σ|Fo|. wR2 = {Σ[w(Fo2 − Fc

2 )2]/Σ[w(Fo2)2 ]}1/2, where w = 1/[σ2(Fo

2)+(aP)2 +

bP], P = (Fo2 + 2Fc

2 )/3.