Date: 8/13/02
Property:
E(lp) -- calculated energy of the lone pair electrons of PZ3.Reference:
N. Koga, C. H. Suresh. "Quantifying the Electronic Effect of Substituted Phosphine Ligands via Molecular Electrostatic Potential." Inorg. Chem., 2002, 41, 1573.
Related Links:
Vmin -minimum electrostatic potential (Analysis);
d(cp)(Analysis)-- distance from the P nucleus to the point of minimum electrostatic potential (Vmin) in PZ3
Summary:
E(lp) = - (0.201±0.002) - (0.0026±0.0004)cd + (0.009±0.002)Ear - (0.006±0.002)pp
n = 26 s = 0.004233 r2 = 0.967 outliers - P(OPh)3
%cd = 58 %q = 0 %Ear = 25 %pp = 17
General Comments:
Data:
|
PZ3 |
E(lp)* |
c d |
q |
Ear |
p p |
|
PH3 |
-0.2751 |
17.00 |
87 |
0.0 |
3.7 |
|
P(n-Bu)H2 |
-0.2479 |
13.10 |
103 |
0.0 |
2.5 |
|
P(i-Bu)H2 |
-0.2459 |
13.20 |
106 |
0.0 |
2.5 |
|
P(OMe)3 |
-0.2507 |
17.90 |
107 |
1.0 |
2.8 |
|
P(OEt)3 |
-0.2461 |
15.80 |
109 |
1.1 |
2.9 |
|
P(OCH2CH2Cl)3 |
-0.2780 |
20.40 |
110 |
0.4 |
3.6 |
|
PMe3 |
-0.2198 |
8.55 |
118 |
0.0 |
0.0 |
|
P(n-Bu)2H |
-0.2289 |
9.20 |
120 |
0.0 |
1.2 |
|
PMe2Ph |
-0.2240 |
10.50 |
122 |
1.0 |
0.0 |
|
PHPh2 |
-0.2263 |
14.50 |
126 |
2.0 |
1.2 |
|
P(OPh)3 |
-0.2326 |
23.4 |
128 |
1.3 |
4.1 |
|
PCl2Ph |
-0.2698 |
32.40 |
131 |
3.7 |
3.5 |
|
PEt3 |
-0.2163 |
6.30 |
132 |
0.0 |
0.0 |
|
PVi3 |
-0.2356 |
13.65 |
132 |
0.0 |
|
|
P(n-Pr)3 |
-0.2159 |
5.40 |
134 |
0.0 |
0.0 |
|
P(n-Bu)3 |
-0.2155 |
5.25 |
136 |
0.0 |
0.0 |
|
PEt2Ph |
-0.2215 |
8.60 |
136 |
1.1 |
0.0 |
|
PMePh2 |
-0.2137 |
12.60 |
136 |
2.2 |
0.0 |
|
PClPh2 |
-0.2334 |
22.80 |
138 |
3.4 |
1.8 |
|
P(CHCH2)Ph2 |
-0.2154 |
13.40 |
140 |
0.0 |
|
|
P(i-Bu)3 |
-0.2079 |
5.70 |
143 |
0.0 |
0.0 |
|
PCy2H |
-0.2253 |
6.60 |
144 |
0.0 |
1.2 |
|
PPh3 |
-0.2118 |
13.25 |
145 |
2.7 |
0.0 |
|
PPh2(p-FC6H4) |
-0.2145 |
14.10 |
145 |
2.7 |
0.0 |
|
P(p-FC6H4)3 |
-0.2197 |
15.70 |
145 |
2.7 |
0.0 |
|
P(i-Pr)3 |
-0.2091 |
3.45 |
160 |
0.0 |
0.0 |
|
PCy3 |
-0.2064 |
1.40 |
170 |
0.0 |
0.0 |
|
P(o-MeC6H4)3 |
-0.2055 |
10.65 |
178 |
2.7 |
0.0 |
|
P(t-Bu)3 |
-0.2004 |
0.00 |
182 |
0.0 |
0.0 |
|
P(NMe2)3 |
-0.1930 |
||||
|
PPh2(m-FC6H4) |
-0.2168 |
||||
|
P(m-FC6H4)3 |
-0.2267 |
||||
|
P(OCH2CCl3)3 |
-0.2973 |
*Calculated energy of the lone pair electrons in PZ3.
Graphical Analysis:
Interpretation of Graphs:
• Plot of data versus
• Slope of the PR3 line (Graph A): The slope is negative and not quite parallel to the line for P(p-XC6H4)3 indicating that there might be a small steric effect.
• Point of intersection of the 2 lines in graph A. The lines intersect at a large positive value of
cd indicating that there is a significant Ear effect.• Plot of E(lp) versus 'i' for PZiY3-i (Graphs B and C): The 'i' plots for the various phosphorus(III) compounds are reasonably linear thereby indicating that all these data are well behaved.
• Outliers: None that are obvious.
• Steric threshold: None that is obvious.
Statistical Analysis:
We began the analysis using all the data and a four parameter fit. The resulting regression equation is
E(lp) = - 0.246 - 0.00117
cd +0.000266q + 0.00314Ear - 0.00602pp|
Predictor |
Coef |
Stdev |
t-ratio |
p |
|
Constant |
-0.24572 |
0.02142 |
-11.47 |
0.000 |
|
c d |
-0.001170 |
0.001080 |
-1.08 |
0.290 |
|
q |
0.0002659 |
0.0001282 |
2.07 |
0.050 |
|
Ear |
0.003138 |
0.004435 |
0.71 |
0.487 |
|
p p |
-0.006021 |
0.003375 |
-1.78 |
0.088 |
s = 0.008261 r2 = 0.873 r2 (adj) = 0.850
Unusual Observations:
Obs. E(lp) Fit Stdev.Fit Residual St.Resid
P(OPh)3 -0.23260 -0.25990 0.00474 0.02730 4.03R
Since the Minitab program identifies P(OPh)3 as an outlier it was dropped from the next analysis. The resulting regression equation is
E(lp) = - 0.206 - 0.00241
cd +0.000032q + 0.00839Ear - 0.00611pp|
Predictor |
Coef |
Stdev |
t-ratio |
p |
|
Constant |
-0.20647 |
0.01228 |
-16.81 |
0.000 |
|
c d |
-0.0024064 |
0.0005862 |
-4.11 |
0.001 |
|
q |
0.00003218 |
0.00007348 |
0.44 |
0.666 |
|
Ear |
0.008392 |
0.002414 |
3.48 |
0.002 |
|
p p |
-0.006112 |
0.001762 |
-3.47 |
0.002 |
s = 0.004313 r2 = 0.967 r2 (adj) = 0.961
Because of it small 't-ratio' and large 'p-value'
q was dropped as a parameter. The resulting and final regression equation isE(lp) = - 0.201 - 0.00258
cd + 0.00914Ear - 0.00588pp|
Predictor |
Coef |
Stdev |
t-ratio |
p |
|
Constant |
-0.201179 |
0.002221 |
-90.60 |
0.000 |
|
c d |
-0.0025784 |
0.0004272 |
-6.04 |
0.000 |
|
q |
||||
|
Ear |
0.009139 |
0.001675 |
5.46 |
0.000 |
|
p p |
-0.005875 |
0.001646 |
-3.57 |
0.002 |
s = 0.004233 r2 = 0.967 r2 (adj) = 0.962
%
cd = 58 %q = 0 %Ear = 25 %pp = 17Stereoelectronic Profiles:
Discussion: As might be expected, the calculated energy of the lone pair of electrons in PZ3 increases as the electron donor capacity of the pendant groups increases (smaller
cd) and as the field effect decreases (smaller pp). Interestingly, there is a significant contribution of Ear to E(lp) -- a possible clue to the nature of Ear.