P(2-py)3M(CO)n(NO+)3-n

P(2-py)3M(CO)n(NO+)3-n

 

  • M = Cr, n = 3, 2, 1
  • M = Mo, n = 3, 2, 1
  • M = W, n = 3, 2, 1

 

  IE (eV)
Cr 6.766
Mo 7.099
W 7.98
NO  9.264


P(2-py)3Cr(CO)3

Ppy3CrCO3.jpg

Structure
The singlet has C3V symmetry, and the triplet has a bent Cr-C-O and has Cs
symmetry.

 

  B3LYP/3-21G* B3LYP/6-31G* B3LYP/3-21G* B3LYP/6-31G*
  singlet singlet triplet triplet
E(a.u.) -2456.4004277 -2468.8988274 -2456.3627013 -2468.8524291
S-T gap 23.7 kcal/mol 29.1 kcal/mol    
P-C 1.827 1.849    
N-Cr 2.094 2.160    
Cr-C 1.806 1.835    
C-O 1.185 1.170    


Excited-State Energies (nm) and Oscillator Strengths

 

  TD B3LYP/3-21G* TD B3LYP/6-31G*  
1 762.8 (2) 0.024 713.0 (2) 0.022
2 536.2 (2) 0.062 519.2 0.155
3 506.4 0.084 516.5 (2) 0.043
4 505.7 (2) 0.014 491.4 (2) 0.010
5 495.6 0.110 399.3 (2) 0.006
6 404.7 (2) 0.011    
7 358.8 0.004    
8 352.1 (2) 0.008    
9 335.9 (2) 0.004    
10 325.2 (2) 0.013    


B3LYP/3-21G*

 Excited State   2:   Singlet-?Sym    1.6254 eV  762.78 nm  f=0.0242
     101 ->103         0.48789
     101 ->105        -0.14381
     102 ->104         0.48784

 Excited state symmetry could not be determined.
 Excited State   3:   Singlet-?Sym    1.6254 eV  762.78 nm  f=0.0242
     101 ->104         0.48825
     102 ->103        -0.48749
     102 ->105        -0.14382

 Excited State   6:   Singlet-E      2.3121 eV  536.24 nm  f=0.0624
     101 ->106        -0.11975
     102 ->105         0.65123
     102 ->107        -0.11988

 Excited State   7:   Singlet-E      2.3122 eV  536.23 nm  f=0.0624
     101 ->105         0.65122
     101 ->107         0.11976
     102 ->106        -0.11987

 Excited State  10:   Singlet-?Sym    2.4483 eV  506.41 nm  f=0.0838
     101 ->103        -0.26969
     101 ->107         0.36270
     102 ->104         0.26981
     102 ->106         0.36344

 Excited State  11:   Singlet-?Sym    2.4520 eV  505.65 nm  f=0.0139
     101 ->105        -0.14613
     101 ->107         0.48180
     102 ->106        -0.48142

 Excited State  12:   Singlet-?Sym    2.4520 eV  505.65 nm  f=0.0140
     101 ->106         0.48194
     102 ->105         0.14613
     102 ->107         0.48128

 Excited State  13:   Singlet-?Sym    2.5018 eV  495.59 nm  f=0.1101
     101 ->103        -0.29512
     101 ->107        -0.33178
     102 ->104         0.29518
     102 ->106        -0.33147
The band at 536 nm is apparently a metal (d) --> ligand (pyridine pi*) transition.

 

                                  MO 101                                                                       MO 102

Ppy3CrCO3_101.jpg Ppy3CrCO3_102.jpg

                                  MO 103                                                                       MO 104
Ppy3CrCO3_103.jpg Ppy3CrCO3_104.jpg

                                  MO 105                                                                       MO 106
Ppy3CrCO3_105.jpg Ppy3CrCO3_106.jpg

                                  MO 107                                    
Ppy3CrCO3_107.jpg

B3LYP/6-31G*

 Excited State   2:   Singlet-?Sym    1.7390 eV  712.97 nm  f=0.0221
     101 ->104        -0.49340
     102 ->103         0.49354
     102 ->105         0.10341

 Excited State   3:   Singlet-?Sym    1.7390 eV  712.96 nm  f=0.0221
     101 ->103         0.49283
     101 ->105        -0.10342
     102 ->104         0.49411

 Excited State   6:   Singlet-?Sym    2.3879 eV  519.22 nm  f=0.1547
     101 ->104         0.42365
     102 ->103         0.42350

 Excited State   7:   Singlet-E      2.4003 eV  516.54 nm  f=0.0434
     101 ->105         0.66919
     101 ->107        -0.10674
     102 ->106        -0.10667

 Excited State   8:   Singlet-E      2.4003 eV  516.53 nm  f=0.0434
     101 ->106        -0.10672
     102 ->105         0.66918
     102 ->107         0.10668

  Excited State  11:   Singlet-?Sym    2.5229 eV  491.43 nm  f=0.0102
     101 ->106         0.48560
     102 ->105         0.13645
     102 ->107        -0.48550

 Excited State  12:   Singlet-?Sym    2.5229 eV  491.43 nm  f=0.0102
     101 ->105         0.13644
     101 ->107         0.48587
     102 ->106         0.48522

 Excited State  16:   Singlet-E      3.1048 eV  399.32 nm  f=0.0058
     101 ->108         0.69712

 Excited State  17:   Singlet-E      3.1049 eV  399.32 nm  f=0.0058
     102 ->108         0.69712



                Experimental UV Spectra


Ppy3CrCO3_UV.gif


                Experimental IR Spectra


Ppy3MCO3_IR.gif
Calculated IR (B3LYP/6-31G*) :

2012 cm-1  (1554) CO symm. stretching
1950 cm-1  (1073) CO asymm stretching (2)
1604 cm-1  (32)  pyridine C-C, C-N

1500 cm-1  (34)  pyridine H rocking
1496 cm-1  (90)  pyridine H rocking (2)
1466 cm-1  (23)  pyridine H rocking
1315 cm-1  (49)  pyridine H rocking
1023 cm-1  (36)  pyridine breathing

Recommended Scaling Factor for B3LYP/6-31G* is 0.9614
(p. 305 in Cramer's book)

 


P(2-py)3Cr(CO)2(NO+)

Ppy3CrCO2NO+.jpg

Structure

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -2472.7456344 -2485.3347621
S-T gap 46.2 kcal/mol  
P-C 1.835 1.852
N-Cr 2.103, 2.153 (3N-Cr) 2.159, 2.197
Cr-C 1.853 1.895
Cr-N 1.650 (Cr-38N) 1.671
C-O 1.166 1.150
N-O 1.212 1.174

 

 


A TD(50-50) calculation shows that at the singlet structure, the lowest triplet state (3A') has an energy 0.90 eV above the  singlet state. Unfortunately no low-lying triplet state is found.

Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G*  
1 507.2 0.007
2 451.4 0.014
3 434.3 0.029
4 409.2 0.012
5 364.2 0.031

 

Triplet State Geometry (bent Cr-N-O)
Ppy3CrCO2NO+_T_bent.jpg
Structure

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -2472.7083543 -2485.2925449
S-T gap 23.4 kcal/mol 26.5 kcal/mol
P-C 1.838 1.854
N-Cr 2.083, 2.119 (3N-Cr) 2.142, 2.170
Cr-C 1.895 1.930
Cr-N 1.859 (Cr-38N) 1.889
C-O 1.164 1.148
N-O 1.253 1.194
A(Cr-N-O) 127.1 131.3


A TD(50-50) calculation shows that at the triplet structure, the lowest triplet state (3A') has an energy 1.42 eV below the singlet state.
E(RPA) =  -2485.32038649, which is now only 9 kcal/mol higher than the singlet energy at the optmized singlet structure, and is 10 kcal/mol lower than the triplet energy at the singlet structure. If the energy of this triplet state can be further optimized, it may have a chance to be the electronic ground state.

If we turn the NO down and keeps the Cs structure, a TD(50-50) calculation shows that the lowest triplet state (3A') has an energy 1.57 eV below the singlet state. E(RPA) =  -2485.34102225, which is now 3.9 kcal/mol lower than the optimized singlet state. Since the ZPE of the triplet state ( 167.2 kcal/mol) is ~1.8 kcal/mol lower than that of the singlet state (169.0), the triplet is now 5.7 kcal/mol lower than the singlet state.


Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*
1 722.9 0.002 796.9 0.010
2 690.3 0.011 688.6 0.001
3 595.1 0.020 656.6 0.001
4 537.3 0.002 504.8 0.013
5 508.5 0.002 492.4 0.003
6 488.1 0.009 475.1 0.003
7 461.9 0.017 466.8 0.014
8 449.6 0.007 433.6 0.008

 

Experimental IR Spectra

Ppy3MCO2NO+_IR.gif

Predicted (B3LYP/6-31G*) IR spectra

Ppy3CrCO2NO+_IR.gif
Triplet:
2127, 2075 CO stretching
1680           NO stretching

Singlet:
2128, 2078 CO stretching
1851           NO stretching

 

 

P(2-py)3Cr(CO)(NO+)2

Ppy3CrCONO2_2+.jpg

Structure

  B3LYP/3-21G* B3LYP/6-31G* B3LYP/6-311G* SP B3LYP/6-311+G* SP BLYP/6-31G*
E(a.u.) -2488.8939751 -2501.5754842 -2501.91037424 -2501.92814666 -2501.69359237
S-T Gap          
P-C 1.837 1.852      
N-Cr 2.107, 2.065 (4N-Cr) 2.147, 2.118      
Cr-C 1.964 2.005      
Cr-N 1.689(37N-Cr) 1.716      
C-O 1.147 1.133      
N-O 1.181 1.148      


B3LYP/6-31G*
Triplet SP at singlet B3LYP/6-31G* geom.(stable=opt): -2501.5137901 (A'')
S-T: 38.7 kcal/mol

However, a TD(50-50) calculation shows that at the singlet structure, there is a low-lying triplet state (3A') with a energy 0.93 eV or 21.4 kcal/mol lower than the  singlet state. E(RPA) =  -2501.60983405
Unfortunately, this state cannot be found with a simple triplet state calculation as mentioned above.
A similar calculation for P(2-py)3Mo(CO)(NO+)2 does not show a low-lying triplet state and the lowest triplet state is 1.75 eV higher in energy.

Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*
1 563.7 0.0005 526.3 0.0005
2 399.7 0.0018 421.1 0.0006
3 395.1 0.0006 394.5 0.0030
4 393.0 0.0005 386.1 0.0010
5 381.7 0.0008 358.6 0.0017

 

 


Ppy3CrCONO2_2+_T.jpg

Structure

  B3LYP/3-21G* B3LYP/6-31G* B3LYP/6-311G* B3LYP/6-311+G* BLYP/6-311G*
E(a.u.) -2488.8793906 -2501.5572722 -2501.89204458 -2501.9103885 -2501.64973299
S-T gap 9.2 kcal/mol 11.4 kcal/mol 11.5 kcal/mol 11.1 kcal/mol 27.5 kcal/mol
P-C 1.838 (P-9C), 1.843 1.852, 1.857      
N-Cr 2.086 (Cr-2N)
2.050 (Cr-3N)
2.033 (Cr-4N)		 2.139
2.093
2.081		      
Cr-C 2.111 2.131      
Cr-N 1.988 (Cr-37N)
1.748 (Cr-38N)		 2.070
1.748		      
C-O 1.143 1.130      
N-O 1.194 (37N-25O)
2.204 (38N-26O)		 1.154
1.165		      
A(Cr-N-O) 135.6 134.9      


A TD(50-50) calculation at the above B3LYP/6-31+G* structure finds a low-lying triplet state that is 1.42 eV below the singlet. E(RPA) = -2501.56916355 and it is 4.0 kcal/mol lower than that of the optimized singlet state. Interestingly, the energy is significantly higher than the triplet energy  calculated at the singlet structure. The geom. with NO pointing down needs to be checked

A TD(50-50) calculation at the above B3LYP/6-31+G* structure with NO pointing down finds a low-lying triplet state that is 1.79 eV below the singlet. E(RPA) = -2501.59087848 and it is 9.7 kcal/mol lower than that of the optimized singlet state.

P(py)3Cr(NO)2 (2+)
B3LYP/6-31G* singlet OPT: -2388.22533
B3LYP/6-31G* triplet OPT:  -2388.22186
S-T: 2.2 kcal/mol

Right now it seems that using TD(50-50) can make prediction that is consistent with experiments.
However, we need to check if this is an artifact of using different basis set. So we also make calculation using SDD for Cr.

P(2-py)3Cr(CO)2NO+ (using B3LYP/6-31G* geom.)
singlet energy at singlet structure : -1527.92751580 (0.0 kcal/mol)
triplet energy at triplet structure: -1527.91660998 (6.8 kcal/mol)
triplet energy with NO down: -1527.93805818 (-6.6 kcal/mol)

P(2-py)3Cr(CO)(NO+)2 (using B3LYP/6-31G* geom.)
singlet energy at singlet structure: -1544.16366672 (0.0 kcal/mol)
triplet energy at singlet structure: -1544.20877941 (-28.3 kcal/mol)
triplet energy at triplet structure: -1544.16167 (1.3 kcal/mol)

So, the calculation with SDD for Cr seems to be consistent with the 6-31G* results.


Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*  
1 679.0 0.003 596.7 0.008
2 637.4 0.008 481.3 0.002
3 470.5 0.002 470.4 0.002
4 456.7 0.005 453.2 0.004
5 441.1 0.002 447.4 0.013
6 414.2 0.003 434.8 0.001
7 410.4 0.010 425.6 0.002
8 365.2 0.008 396.6 0.004


            Experimental IR Spectra
Ppy3MCONO_2+_IR.gif

 

Calculated (B3LYP/6-31G*)  IR Spectra

Ppy3CrCONO2_2+_IR.gif
Triplet:
2259             CO stretching
1954, 1862   NO stretching

1633-1639
1472-1509
1320-1328    pyridine H in-plane bending
1123 

1035-1045    Pyridine breathing

795                Pyridine H out-of-plane bending        

Singlet:
2229              CO stretching
2015, 1934    NO stretching

 


P(2-py)3Mo(CO)3
Ppy3MoCO3.jpg
Structure

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -5376.0215894 -1492.7677958
P-C 1.836 1.853
N-Mo 2.262 2.299
Mo-C 1.974 1.971
C-O 1.185 1.172


Ppy3MoCO3_UV.gif
Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*
1 700.7 (2) 0.024 676.5 (2) 0.023
2 516.0 (2) 0.050 521.6 0.164
3 511.5 0.186 503.4 (2) 0.043
4 485.3 (2) 0.013 477.9 (2) 0.011
5 481.8 0.010 304.2 (2) 0.028


Calculated (B3LYP/6-31G* IR Spectra)

C-O   2005, 1934 (2) cm-1

 

 

P(2-py)3Mo(CO)2(NO+)
Ppy3MoCO2NO+.jpg
Structure

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -5392.3544707 -1509.195122
P-C 1.842 1.856
N-Mo 2.254, 2.287 (3N-Mo) 2.288, 2.308
Mo-C 2.031 2.026
Mo-N 1.821 1.818
C-O 1.167 1.153
N-O 1.207 1.177


Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*  
1 482.3 0.007 464.3 0.008
2 432.2 0.002 421.6 0.009
3 414.7 0.044 405.1 0.033
4 387.8 0.029 374.8 0.027
5 362.0 0.004 343.5 0.015
      342.0 0.025
      323.1 0.024
      322.9 0.013


Calculated (B3LYP/6-31G* IR Spectra)

C-O   2110, 2051 cm-1
N-O   1823 cm-1

Triplet Structure

  B3LYP/6-31G*
E(a.u.) -1509.13160803
S-T gap 39.9 kcal/mol
P-C 1.858
N-Mo 2.274
Mo-C 2.030
Mo-NO 2.025
C-O 1.153
N-O 1.194
A(Mo-N-O) 130.8


A TD(50-50) calculation at the above structure finds a low-lying triplet state that is 1.08 eV below the singlet. E(RPA) = -1509.16891 and it is 16.4 kcal/mol higher than that of the optimized singlet state. This implies for P(2-py)3Mo(CO)2NO+, the S-T gap might also be small. The geom. with NO pointing down needs to be checked.

A TD(50-50) calculation using the above structure with NO pointing down finds a triplet state at is 1.08 eV below the singlet. E(RPA) = -1509.17585756 and it is 12.1 kcal/mol higher than that of the optimized singlet state.

 

P(2-py)3Mo(CO)(NO+)2
for 6-31G*, Mo: SDD
Ppy3MoCONO2_2+.jpg
Singlet Structure

 

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -5408.4977614 -1525.4378026
P-C 1.843 1.857
N-Mo 2.236, 2.202 (4N-Cr) 2.257, 2.237
Mo-C 2.160 2.138
Mo-N 1.867(37N-Cr) 1.867
C-O 1.149 1.135
N-O 1.181 1.153


Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*  
1 602.9 0.0007 565.6 0.0009
2 552.9 0.0001 525.2 0.0001
3 442.0 0.0003 427.0 0.0007
4 429.5 0.0001 420.1 0.0004
5 417.6 0.0003 383.2 0.0014
6 382.3 0.0031 359.0 0.0029
      348.7 0.0012
      343.7 0.0015


Calculated (B3LYP/6-31G* IR Spectra)

C-O   2210 cm-1
N-O   1964 (symm), 1895 cm-1 (asymm)

B3LYP/6-31G*
Triplet SP at singlet B3LYP/6-31G* geom.(stable=opt): -1525.37325018 (A')
S-T: 40.5 kcal/mol

Triplet Structure

  B3LYP/6-31G* B3LYP/6-311G* B3LYP/6-311+G*
E(a.u.) -1525.39084    
S-T gap 29.5 kcal/mol    
P-C 1.862, 1.856    
N-Mo 2.206
2.207
2.268		    
Mo-C 2.169    
Mo-NO 2.179*
1.835		    
C-O 1.135    
N-O 1.159*
1.163		    
A(Cr-N-O) 134.5*    

*for the bent NO

A TD(50-50) calculation at the above structure finds a low-lying triplet state that is 1.12 eV below the singlet. E(RPA) = -1525.42132 and it is 10.3 kcal/mol higher than that of the optimized singlet state. This implies for P(2-py)3Mo(CO)(NO)22+, the S-T gap might also be small. The geom. with NO pointing down needs to be checked.

 

 


P(2-py)3W(CO)3
Ppy3W(CO)3.jpg
Structure

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -1484.7972365 -1491.660976
P-C 1.831 1.850
N-W 2.218 2.287
W-C 1.987 1.984
C-O 1.188 1.174


Ppy3WCO3_UV.gif

Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*  
1 723.7 (2) 0.022 711.3 (2) 0.023
2 524.6 (2) 0.076 521.6 (2) 0.054
3 490.3 0.206 521.4 0.188
4 488.0 (2) 0.016 490.4 (2) 0.012
5 484.2 0.036 398.6 (2) 0.007
6 394.3 (2) 0.011 299.9 (2) 0.029
         


Calculated (B3LYP/6-31G* IR Spectra)

C-O   2000, 1930 (2) cm-1

 

 

P(2-py)3W(CO)2(NO+)

Structure

 

 

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -1501.1340921 -1508.0922016
P-C 1.839 (2), 1.842 1.855, 1.858
N-W 2.231, 2.247 (3N-Mo) 2.288, 2.308
W-C 2.018 2.027
W-N 1.836 1.833
C-O 1.172 1.156
N-O 1.217 1.182


Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*  
1 556.1 0.009 502.9 0.008
2 470.6 0.043 443.6 0.039
3 442.0 0.005 423.6 0.005
4 426.5 0.045 394.9 0.041
5 399.7 0.049 370.6 0.026
6 389.5 0.032 366.6 0.030
7 366.0 0.008 334.1 0.027
8 348.5 0.031 315.4 0.017
9 339.7 0.023    


Calculated (B3LYP/6-31G* IR Spectra)

C-O   2098 (symm), 2036 cm-1
N-O   1806 cm-1

Triplet Structure

  B3LYP/6-31G*
E(a.u.) -1508.0242165
S-T gap 42.2 kcal/mol
P-C 1.857
N-W 2.267,2.274
W-C 2.025
W-NO 2.021
C-O 1.157
N-O 1.200
A(W-N-O) 130.7


A TD(50-50) calculation at the above structure finds a low-lying triplet state that is 1.05 eV below the singlet. E(RPA) = -1508.06770506 and it is 15.4 kcal/mol higher than that of the optimized singlet state. This implies for P(2-py)3W(CO)2NO+, the S-T gap might also be small. The geom. with NO pointing down needs to be checked.

A TD(50-50) calculation using the above structure with NO pointing down finds a triplet state at is 1.03 eV below the singlet. E(RPA) = -1508.06608385 and it is 16.4 kcal/mol higher than that of the optimized singlet state.

 

 

P(2-py)3W(CO)(NO+)2

Singlet Structure

 

  B3LYP/3-21G* B3LYP/6-31G*
E(a.u.) -1517.7748331 -1524.3419815
P-C 1.835 (2), 1.826 1.857
N-W 2.200, 2.189 (4N-Cr) 2.257, 2.240
W-C 2.021 2.126
W-N 1.896 (37N-W) 1.875
C-O 1.175 1.137
N-O 1.263 1.159


Excited-State Energies (nm) and Oscillator Strengths

  TD B3LYP/3-21G* TD B3LYP/6-31G*
1 763.1 0.007 580.1 0.001
2 759.1 0.012 422.9 0.001
3 524.2 0.018 360.6 0.003
4 518.8 0.014 356.2 0.003
5 497.6 0.009 348.1 0.002
6 440.9 0.007 340.9 0.003
7 436.5 0.117 348.7 0.0012
8 397.8 0.015 343.7 0.0015
9 392.2 0.045    
10 371.2 0.011    
11 368.6 0.009    


Calculated (B3LYP/6-31G* IR Spectra)

C-O   2197 cm-1
N-O   1940 (symm), 1876 cm-1 (asymm)

Triplet Struicture

 

  B3LYP/6-31G* B3LYP/6-311G* B3LYP/6-311+G*
E(a.u.) -1524.28973    
S-T gap 32.8 kcal/mol    
P-C 1.860, 1.854    
N-W 2.208
2.213
2.276		    
W-C 2.143    
W-NO 2.093*
1.841		    
C-O 1.137    
N-O 1.170*
1.168		    
A(W-N-O) 140.1*    


A TD(50-50) calculation at the above structure finds a low-lying triplet state that is 0.78 eV below the singlet. E(RPA) = -1542.32419 and it is 11.2 kcal/mol higher than that of the optimized singlet state. This implies for P(2-py)3W(CO)(NO)22+, the S-T gap might also be small. The geom. with NO pointing down needs to be checked.