J . Am. Chem. Soc. 1985, 107, 8043-8049
8043
Electronic Structure of Three-Membered Rings Containing P Atoms-PE Spectroscopic Investigations and Model Calculations Rolf Gleiter,*+ Wolfgang Schafer,+and Marianne Baudled Contribution from the Institut fur Organische Chemie der Universitat Heidelberg, Im Neuenheimer Feld 270, 0-6900 Heidelberg, Germany, and the Institut fur Anorganische Chemie der Universitat Koln, Greinstrasse 6, 0-5000 Koln 41, Germany. Received March 8, 1985
Abstract: The He I photoelectron (PE) spectra of three-membered rings with one to three phosphorus atoms have been measured. The assignment of the first bands is based on empirical correlations and on calculations using semiempirical models (MNDO, MIND0/3) as well as the Hartree-Fock SCF method. These investigations permit deductions at the sequence of the highest occupied MO’s of phosphirane, diphosphirane, cyclotriphosphane, thiadiphosphirane, and azadiphosphirane. The PE spectra of a diphosphaarsirane (t-BuP),(t-BuAs) and of a cyclotriarsane (t-BuAs), also have been recorded and their electronic structures are discussed.
Three-membered rings containing phosphorus and arsenic have come into focus due to the recent synthetic success in several laboratorie~’-~ and the recognition that also in larger molecules the three-membered ring moiety serves as a building To understand the bonding properties in compounds containing three-membered rings with P atoms we have investigated the H e I photoelectron (PE) spectra of a series of model compounds. The compounds are the following: trans-1 -tert-butyl-2-methylphosphirane (la),9 1,2-di-tert-butyldiphosphirane(2a),lo tritert-butylcyclotriphosphane (3a),” 2,3-di-tert-butyl-l-thiadiphosphirane (4a),I2 1-isopropyl-2,3-di-tert-butyl1,2,3-azadiphosphirane (5a),I3 tri-tert-butyldiphosphaarsirane(6),14 and tri-tert-butylcyclotriarsane(7).5 R
A
R/P-P,R R’ = tert-butyl la R~=CH, R’= ~ 2 ’CH3 ’b R1=R2-H IC
R=tert-butyl R=CH, R=H
8’
2a 2b 2c
R=tert-butyl R=CH, R=H
3a 3b 3c
+
/”\
xp-px 6
+ /”\
AS -AS X
x
7 PE spectroscopic studies on molecules are especially useful to chemists interested in the electronic structure of molecules if the PE bands can be correlated with the molecular orbitals (MO’s) obtained from the corresponding model calculation. Since our argumentation is based on the M O description of molecules 1-7 we shall start our discussion describing the results of the model calculations. Model Calculations We have carried out semiempirical (MNDOI5 and MIND0/3I6) and a b initio calculations using a minimal basis (STO3GI9). The tert-butyl groups were not considered explicitely. They
’Institut fur Organische Chemie der Universitat Heidelberg. Institut fur Anorganische Chemie der Universitat Koln.
0002-7863/85/1507-8043$01.50/0
were replaced by methyl groups for the semiempirical calculations (lb-5b) or hydrogen atoms (models lc-5c). For 4 and 5 the M N D O method has to be used since the M I N D 0 / 3 procedure provides no parameters to treat P-S and P-N bonds. Since for most compounds no geometrical parameters have been reported, we have calculated them using the semiempirical procedures by minimizing the heat of formation for the methyl derivatives 1b-5b as well as the parent compounds IC-5c with respect to the bond lengths and bond angles. For the HF-SCF calculation on lc-3c we adopted the geometries derived by the M I N D 0 / 3 method;l6I8
(1) Baudler, M. Angew. Chem. 1982, 94, 520; Angew. Chem., Int. Ed. Engl. 1982, 21, 492. Baudler, M. Z . Chem. 1984, 24, 352 and references therein. (2) Cowley, A. H.; Furtsch, T. A.; Dierdorf, D. S. J . Chem. SOC.,Chem. Commun. 1970, 523. Smith, L. R.; Mills, J. L. J . Am. Chem. SOC.1976, 98, 3852. Wolcott, R. A,; Mills, J. L. Inorg. Chim. Acta 1978, 30, L 331. (3) Baudler, M.; Carlsohn, B.; Bohm, W.; Reuschenbach, G . Z . Naturforsch. 1976, B31, 558. Baudler, M.; Carlsohn, B.; Kloth, B.; Koch, D. Z . Anorg. Allg. Chem. 1977,432, 67. Baudler, M.; Koch, D.; Tolls, E.; Diedrich, K. M.; Kloth, B. Ibid. 1976, 420, 146. (4) Baudler, M.; Habermann, D. Angew. Chem. 1979, 91, 939; Angew. Chem., Int. Ed. Engl. 1979, 18, 877. (5) Baudler, M.; Bachmann, P. Angew. Chem. 1981, 93, 112; Angew. Chem., Int. Ed. Engl. 1981, 20, 123. (6) Fritz, G.; Holderich, W. Naturwissenschaften 1975, 62, 573; Honle, W.; von Schnering, H. G. Z . Anorg. Allg. Chem. 1978, 440, 171. (7) von Schnering, H. G. Angew. Chem. 1981,93,44; Angew. Chem., Int. Ed. Engl. 1981, 20, 33. von Schnering, H. G. In ‘Homoatomic Rings, Chains and Macromolecules of Main Group Elements”; Rheingold, A. L., Ed.; Elsevier Scientific Publishing Co.: Amsterdam, 1977; p 317 and references therein. (8) Ellermann, J.; Schossner, H. Angew. Chem. 1974, 86, 646; Angew. Chem., Int. Ed. Engl. 1974, 13, 601. Thiele, G.; Zoubek, H.; Lindner, A,; Ellermann, J. Angew. Chem. 1978, 90, 133; Angew. Chem., Int. Ed. Engl. 1978, 17, 135. Schmettow, W.; von Schnering, H. G. Angew. Chem. 1977, 89, 895; Angew. Chem., Int. Ed. Engl. 1977, 16, 857. (9) Baudler, M.; Germeshausen, J. Chem. Ber. 1985, 118, 4285. (10) Baudler, M.; Saykowski, F. Z . Naturforsch. 1978, B33, 1208. ( 1 1) Baudler, M.; Hahn, J.; Dietsch, H.; Furstenberg, G. Z . Naturforsch. 1976, B31, 1305. (12) Baudler, M.; Suchomel, H.; Furstenberg, G.; Schings, U. Angew. Chem. 1981, 93, 1087; Angew. Chem., Int. Ed. Engl. 1981, 20, 1044. (13) Baudler, M.; Kupprat, G. Z . Naturforsch. 1982, B37, 5 2 7 . (14) Baudler, M.; Klautke, S . Z . Naturforsch. 1981, 836, 527. (15) Dewar, M. J. S.;Thiel, W. J . A m . Chem. SOC.1977, 99,4899,4907. Bischof, P.; Friedrich, G. J . Comput. Chem. 1982, 3, 486. (16) Bingham, R. C.; Dewar, M. J. S . ; Lo, D. H. J. Am. Chem. SOC.1975, 97, 1285. The calculations were carried out with MOPN (QCPE 1979, 12, 383”) with use of modified parameters.ls (17) Bischof, P. J . Am. Chem. SOC.1976, 98, 6844. (18) Frenking, G.;Gotz, H.; Marschner, F. J. Am. Chem. SOC.1978, 100, 5295. (19) Gaussian 80: Binkley, J. S.; Whiteside, R. A,; Hariharan, P. C.; Seeger, R.; Pople, J. A.; Hehre, W. J.; Newton, M. D. QCPE 1978, 14, 468.
0 1985 American Chemical Society
8044 J . Am. Chem. SOC.,Vol. 107, No. 26, 1985
Gleiter et ai.
Table I. Most Relevant Geometrical Parameters Calculated for l b to Sc. For lb-3c We List the M N D O (First Line) and M I N D 0 / 3 Parameters. Heat of Formation (AHf') in kcal/mol, Bond Length in A
AH,'
1-2
2-3
1-4
4-5
lb
-2 1.27 21.80
1.78 1.90
1.52 1.52
1.76 1.84
4.23 4.52
IC
0.79 21.42
1.77 1.87
1.51 1.50
1.34 1.42
2.68 2.95
2b
-40.84 2.67
2.05 2.29
1.75 1.84
1.75 1.83
4.54 5.10
2c
-2.81 11.20
2.04 2.21
1.75 1.84
1.34 1.43
3.66 4.01
3b
-52.99 23.10
2.04 2.16
2.04 2.16
1.74 1.85
3.48 4.15
4.56 5.02
3c
4.82 17.01
2.04 2.10
2.04 2.12
1.34 1.44
2.65 2.95
3.68 3.99
4b
-40.24
2.05
1.91
1.75
4.57
2.04
1.57
1.34
3.69
compound 4
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3
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