2803
Inorg. Chem. 1989. 28. 2803-2806
comparison of the F peak-to-peak height with those of the metals is not meaningful. Figure 4 shows Auger spectra for films grown from Ca[HFAI2 with and without O2and from Ca[TFAI2 with 02.Although the C and Ca lines overlap, it is apparent that films grown with O2 have very little C. However, the C content is large in films grown without 02.All the C a films contained a substantial amount of F but only several percent of 0. Note that the Ca lines at 291 and 294 eV are resolved for the film grown from Ca[TFA],. Figure S shows an Auger spectrum for a film grown from Sr[HFA], with 0,. The dominant peaks are Sr and F, although there are several percent of C and 0. The carbon is in the carbidic form. Figure 6 shows an Auger spectrum from a film grown from Ba[HFAI2 with 0,. The dominant peaks are Ba and F. The line shapes of the Ba lines between 40 and 80 eV indicate that the Ba is mostly However, the presence of the peak near 68 eV indicates that some of the Ba was oxidized, which is commensurate with the small 0 line. For a fully oxidized Ba surface,25 the ratio of the peak-to-peak heights of the Ba (584 eV) line to the 0 (510 eV) line would be 0.5. The peak-to-peak height of the C line (not shown) was -4% of that of the Ba (584 eV) line. The C had a carbidic line shape.
y
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ENERGY (ev)
Figure 5. Auger electron spectrum of the SrF, film.
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Acknowledgment. W e thank Mark Ross and John Callahan for their assistance with the mass spectral analysis. Registry No. Ba[HFA],, 118131-57-0; Sr[HFA],, 121012-89-3; Ca[HFA],, 121012-90-6; Ba[TFA],, 84653-56-5; Sr[TFA],, 12101291-7; Ca[TFAI2, 73592-45-7; BaF,, 7787-32-8; SrF2, 7783-48-4; CaF2, 7789-75-5; Si, 7440-21-3. ~
(23) Strecker, C. L.; Noddeman, W. E.; Grant, J. T. J . Appl. Phys. 1981, 5 2 , 692 1.
(24) Haas, G. A.; Marian, C. R. K.; Shih, A. Appl. SurJ Sci. 1983, 16, 125. (25) Shih, A.; Hor, C.; Haas, G.A. Appl. Surf. Sci. 1979, 2, 112. (26) Powder Diffraction File (ASTM Cards); Joint Committee on Powder Diffraction Standards, Swarthmore, PA; Files 4-0864 (CaF,), 6-0262 (SrF,), 4-070 (BaF,).
Contribution from the Department of Chemistry, The University of Calgary, Calgary T2N 1N4, Alberta, Canada
Lewis Base Properties of 1X5,3X5-Diphospha-5-thia-2,4,6-triazines: Crystal and Molecular Structures of (Ph4P2N3SPh)Me+CF3S03Tristram C h i v e r s , * James Fait, and Stephen W. Liblong Received December 28, 1988 The behavior of Ph4P2N3SPh(1) toward Lewis and Bronsted acids has been investigated, and the following adducts have been isolated: (Ph4P2N3SPh)H*BFL (5), (Ph4P,N3SPh)Me*CF3SO< (6), Ph4P2N3SPh.BF3(7), and Ph4P2N3SPh.BC1, (8). The 3'P NMR spectrum of 6 reveals inequivalent phosphorus atoms, indicating that the methyl group is coordinated to a nitrogen atom between a phosphorus and a sulfur atom of the PzN3Sring. An X-ray structural determination has confirmed this assignment. The crystals of 6 are monoclinic and belong to the space group P 2 , / c , with a = 10.317 (2) A, b = 22.849 (4) A, c = 14.104 (3) A, @ = 102.94 (2)O, V = 3241 (1) A3, and Z = 4. The final R and R, values were 0.046 and 0.049, respectively. The P2N3S ring in 6 adopts a highly distorted boat conformation. The bond lengths to the coordinated nitrogen are lengthened compared to those of the parent ring system [1.69 vs 1.62 A for d(S-N) and 1.69 vs 1.62 A for d(P-N)], and the adjacent S-N and P-N NMR spectrum of 5 exhibits a singlet consistent with protonation at the unique bonds are shortened slightly. By contrast, the nitrogen atom of the P2N3Sring. Compounds 7 and 8 display NMR spectra consistent with the formation of both symmetrical and unsymmetrical adducts. The lack of regioispecificity in the formation of adducts between the P2N3Sring and Lewis or Bronsted acids is discussed in terms of the electronic structure of the heterocycle.
Introduction All four members of the series of inorganic heterocycles containing alternating phosphorus or sulfur and nitrogen atoms, 1-4, are known,' and their n-electronic structures have been compared?
The Lewis base properties of 1,33,4 and 4' have also been investigated, and the formation of a variety of adducts with Lewis ( 1 ) Chivers, T. Acc. Chem. Res. 1984, 17, 166.
(2) Burford, N.; Chivers, T.; Hojo, M.; Laidlaw, W. G.; Richardson, J. F.; Trsic, M. Inorg. Chem. 1985, 24, 709. (3) Allen, C. W. In The Chemistry of Inorganic Homo- and Heterocycles; Haiduc, I., Sowerby, D. B., Eds.; Academic: London, 1987; Vol. 2, p (4)
1
2
3
4
0020-1669/89/1328-2803$01 .SO/O
563. Chivers, T.; Liblong, S. W.; Richardson, J. F.; Ziegler, T. Inorg. Chem. 1988, 27, 860.
0 1989 American Chemical Society
Chivers et ai.
2804 Inorganic Chemistry, Vol. 28, No. 14, 1989 or protonic acids occurs via coordination to an endocyclic nitrogen atom. The limited structural information available for such adducts of 1 reveals lengthened skeletal bonds to t h e protonated nitrogen atoms and only minor perturbations to the conformations of t h e P3N3 By contrast, the interaction of t h e a-electron-rich ring S3N< (4) with protonic acidsSor other electrophiles* results in a major structural reorganization to give ring-contracted products. For the hybrid ring systems 2 and 3, the site of attack is of interest in addition to the structural changes that accompany adduct formation. In the case of 3 (R = Ph) coordination occurs exclusively a t a nitrogen a t o m between a phosphorus atom and a sulfur atom and is controlled by electrostatic effects4 No evidence for t h e formation of diadducts of 3 (R = Ph) was obtained.* Coordination t o an electrophile also imposes a marked perturbation on both t h e conformation of t h e ring and t h e S-N bond length^.^ T h e substantial structural changes t h a t accompany adduct formation by 3 ( R = Ph) and 4 have been attributed to the ready polarization of the a* electrons in these a-electron-rich ~ y s t e m s . ~ . ~ In this context it was of interest t o compare the Lewis base properties of the a-electron-precise ring, 2,' with those of 1, 3, and 4. Specifically, we set out t o determine ( a ) t h e preferred coordination site, (b) the structural modifications that occur upon adduct formation, and (c) t h e production of diadducts in t h e interaction of 2 with Lewis and Bronsted acids. The phenyl derivative, 2 (X = R = Ph), was chosen because it is readily ~ r e p a r e dis, ~air stable, and has been structurally characterized.2 W e describe here t h e isolation and spectroscopic (31PN M R ) characterization of crystalline adducts of 2 (X = R = Ph), the X-ray structural determination of (Ph4P2N3SPh)Me+CF3S0,( 6 ) , and t h e formation of diadducts in solution. T h e apparent lack of regiospecificity in adduct formation is discussed in terms of t h e electronic structure of t h e P2N3St ring. Experimental Section Reagents and General Procedures. All solvents were dried and distilled before use: methylene dichloride (P205),n-pentane, and diethyl ether (Na). All reactions and the manipulation of moisture-sensitive products were carried out under an atmosphere of nitrogen (99.99% purity) passed through Ridox, P205,and silica gel. Chemical analyses were performed by the Analytical Services of the Department of Chemistry, The University of Calgary, and by the Canadian Microanalytical Service Ltd., Vancouver, BC, Canada. Ph4P2N3SPhwas prepared by the literature method.' Other chemicals were obtained from Aldrich and used as received: HBF4.Et20, CF,SO,Me, BF,.Et,O, and BCI, (1.0 M solution in hexanes). Instrumentation. Infrared spectra were recorded as Nujol mulls (KBr windows) or KBr pellets on a Nicolet 5DX FT IR spectrometer. NMR spectra were recorded on a Varian XL-200 instrument. IH and I3C chemical shifts are reported in ppm downfield from Me4Si. ,IP chemical shifts are quoted with reference to external 85% H3P04. Preparation of (Ph4P2N,SPh)HtBF;. A solution of HBF4.Et20 (0.40 g, 2.50 mmol) in CH2C12(3 mL) was added dropwise to a solution of Ph4P2N,SPh (1.00 g, 1.92 mmol) in CH2CI2( 5 mL), and the mixture was stirred for 2 h at 23 "C. Addition of n-pentane (50 mL) with rapid stirring produced a colorless precipitate of (Ph4P2N3SPh)HtBF,' ( I .13 g, 1.85 mmol). Anal. Calcd for C30H2,BF4N,P2S: C, 59.13; H, 4.30; N, 6.90. Found: C, 57.60; H, 4.27; N, 6.66. IR (cm-I): 3198 w, 3065 w, 1441 s, 1315 m, 128511-1,121Ovs, 1182vs, 1122vs, 1074vs, 1058vs, 1031 s, 1023 s, 996 vs, 861 s, 816 s, 759 s, 749 s, 736 s, 726 vs, 700 s, 687 vs, 670 rn, 61 1 m, 551 vs, 527 rn, 507 vs. NMR data are given in Table I. Preparation of (Ph4P2N3SPh)Me+CF,S0,-. An excess of CF,SO,Me (0.36 g, 2.2 mol) was added to a solution of Ph4P2N3SPh(0.97 g, 1.9 mmol) in CH2CI2( I O mL), and the mixture was stirred at 23 OC for 1 h. This solution was then added dropwise to rapidly stirred n-pentane
( 5 ) Marcellus, C. G.; Oakley, R. T.; Cordes, A. W.; Pennington, W. T. Can. J . Chem. 1984, 62, 1822. (6) Mani, N. V.; Wagner, A. J. Acta Crystallogr., Sect. 8 1984, 827, 51. (7) (a) Allcock, H. R.; Bissell, E. C.; Shawl, E. T. Inorg. Chem. 1973,IZ, 2963. (b) MacDonald, A. L.; Trotter, J. Can. J . Chem. 1974, 52,734. (8) Bojes. J.; Chivers, T. Inorg. Chem. 1978, 17, 318. (9) Chivers, T.; Rao, M. N. S. Inorg. Chem. 1984, 23, 3605. (IO) Haiduc, 1.; Sowerby, D. B. The Chemistry of Inorganic Homo- and Heterocycles; Academic: London, 1987; Vol. 1, p 12.
Table 1. NMR Data for Lewis Acid Adducts and Protonated and Methylated Derivatives of Ph4P2N3SPh(2, X = R = Ph) adducts" 6(3IP)b 2-(Ph4P2N3SPh)H*BF,' ( 5 ) 17.7 26.0, 20.5' 4-(Ph4P2N,SPh)Me+CF3SO
