J . Org. Chem. 1987, 52, 2938-2939
2938
Table 11. Calculated and ExDerimental Molecular Geometries obsd (8,or deg) method, ref MM1 (calcd) methyl phosphine P-H
1.423 f 0.007 1.858 f 0.003 93.4 96.5 (assumed) (93.4) 109.6 f 1.0
P-c H-P-H H-P-C P-C-H dimethylphosphine P-H
ED, 6 MW, 7
110.5
1.445 f 0.02 1.853 f 0.003 96.5 (assumed) (96.95) 109.8 f 0.7 99.2 f 0.6
P-c H-P-C P-C-H c-P-c trimethylphosphine
P-c P-C-H
c-P-c
ethylphosphine (gauche) P-c c-c-P ethylphosphine (trans) P-c
e-c-P
1.438 1.857 94.5 95.9
ED, 6
1.439 1.853 97.0
MM2 (calcd) 1.4376 1.8597 94.585 95.957 110.350/ 111.522 1.4381 1.8578 96.983
MW, 8
110.4 98.0
110.235 98.174
1.846 f 0.003 110.7 f 0.5 98.6 f 0.3
ED, 10
1.847 110.4 99.3
1.8545 110.268 99.007
1.880 f 0.002 110.1 f 0.2
MW, 11
1.864 112.5
1.8667 112.782
1.876 f 0.002 115.2 f 0.1
MW, 11
1.861 115.2
1.8665 114.374
1.828 f 0.048 103.0 f 0.2 124.0 f 0.38 116.08 f 0.37
X-ray, 12
1.828 103.1 123.5 117.5
1.8282 101.453 124.035 117.275
triphenylphosphine
P-c c-P-c P-c-c
Table 111. Rotational Barriers (kcal/mol) and Dipole Moments (D) barrier dipole moment obsd MM1 MM2 obsd MM1 1.96 1.84 1.94 1.10 0.98 2.22 2.20 2.11 1.23 1.18 2.38 1.19 1.28 2.6 2.53
methylphosphine dimethylphosphine trimethylphosphine ethylphosphine energy difference between gauche terms tert-butylphosphine tri-tert-butylphosphine isopropylphosphine gauche to trans gauche to gauche triphenylphosphine di-tert-butylphosphine
0.57 f 0.28 3.19 8.6
MM2 0.99 1.11
1.19
0.57 2.79 8.3
3.01 8.80
3.31 2.85
3.30 2.85 1.40
