Inorg. Chem. 1982, 21, 3123-3126
3123
Contribution from the Department of Chemistry, Texas A&M University, College Station, Texas 77843, and the Laboratoire de Chimie Mindrale Moldculaire, Equipe de Recherche Associde au CNRS, Parc Valrose, 06034, Nice Cedex, France
Structure, Bonding, and Chemistry of cfoso-Tetraphosphorus Hexakis(methylimide), P4(NCH3)6,and Its Derivatives. 3. Structures of the Dithio and Trithio Derivatives F. ALBERT COTTON,*'* JEAN G. RIESS,*lb CATHERINE E. RICE,Ia and B. RAY STULTSIa
Received July 14, 1981 The crystal and molecular structures of the title compounds, S2P4(NMe)6and S3P4(NMe)6,have been determined. The former gives monoclinic crystals belonging to the space group P2,/n with unit cell dimensions a = 12.582 (3) A, b = 13.110 (3) A, c = 9.747 (2) A, @ = 95.00 (2)", V = 1602 (1) A3, dald = 1.502 g/cm3 for Z = 4, and M , = 362.27. The latter crystallizes in the orthorhombic space group Pbca with a = 9.839 (4) A, b = 13.383 (7) A, c = 25.839 (10) A, V = 3402 (3) A', dald = 1.540 g/cm3 for Z = 8, and M , = 394.23. The results presented here together with those reported earlier for P4(NCH3),, SP4(NCH3)6,and S4P4(NCH3),allow a search for, and analysis of, systematic trends in N-P bond lengths. Because of scatter in the data for each compound, error bars on average values are fair1 large. The following are the The S2P4(NCH3)6structure averages: P-NP, 1.70 (1) A; P-NPS, 1.73 (2) A; SP-NP, 1.65 (2) A; SP-NPS, 1.68 (2) is the most precise of those determined, and the four types of P-N distances therein have higher precision than the overall averages for all compounds. The coplanarity of the bonds about all the nitrogen atoms and the significant shortening, by 0.07-0.10 A, of the P-N bonds with respect to P(III)-N(sp2) and P(V)-N(sp2) standards are interpreted as resulting from N(pa)-(P(dr) contributions, with total bond orders of ca. 1.2-1.3. Some transmission of electronic effects is also seen in the SP-N-P pattern and is attributed to the N p r electrons being more attracted to the SP-N side at the expense of the N-P side.
1.
Introduction In previous publications we have reported the molecular and Crystal Structures O f P4(NMe)6,53Op4(NMe)6,3S4P4(NMe)6,3 and SP4(NMe),4and commented on the structure parameters and how they are affected by attachment of 0 or S atoms to the phosphorus atoms. With this paper we complete the structural information on the S,P4(NMe)6 (n = 0-4) series by reporting the structures of the compounds with n = 2 or 3. In SP4(NMe)6 an interesting pattern of variation in the N-P distances was observed and the present structures afford the opportunity to see if such a pattern is a consistent one for molecules containing an incomplete set of sulfur atoms.
Procedure The compounds were prepared by methods previously de~cribed.~ Crystals were grodn by sublimation. Freshly sublimed P4(NCH3)QS2 (120 " c , 2 mmHg), or P4(NCH3)6S3(150 "C, 2 mm Hg), was transferred under dry argon to one end of a 20 cm long, 2 cm diameter glass tube, which was evacuated and sealed. The tube was then heated in a horizontal tubplar furnace having a regular temperature gradient from 65 to 25 "C. Transparent well-formed crystals were collected at the coldest end after 4-5 days. The crystals appear to be very deformable and fragile and must be transported and handled gently. The general crystallographic procedures have already been described3s4and referenced. S2P4(NCH3)6. Data Collection. The crystal chosen was an approximate sphere (diameter -0.4 mm); it was lightly coated with epoxy cement and mount$d on a glass fiber. Data were collected at 21 1 "C on a Syntex P1 automated diffractometer using Mo K a radiation monochromatized with a graphite crystal in the incident beam,and the usual automatic centering and indexing procedures3s4 were followed. Preliminary photographs revealed monoclinic symmetry. The systematic absences (OkO, k # 2n; hOl, h + 1 # 2n) uniquely established the space group as R 1 / n(a nonstandard setting of R l / c ,No. 14). The principal crystallographicdata are as follows: a = 12.582 (3) A, b = 13.110 (3) A, c = 9.747 (2) A, /3 = 95.00 (2)", V = 1602 (1) A', d,,, = 1.502 g/cm3 for Z = 4, and a molecular weight of 362.27.
*
(1) (a) Texas A&M University. (b) Laboratoire de Chimie Minerale
MolEculaire. (2) Cotton, F. A.; Troup, J. M.; Casabinaca, F.; Riess, J. G. Inorg. Chim. Acta 1974, 11, L33. (3) Casabianca, F.; Cotton, F. A.; Riess, J. G.; Rice, C. E.; Stults, B. R. Inorg. Chem. 1978, 17, 3232. (4) Cotton, F. A,; Rim, J. G.; Rice, C. E.; Stults, B. R. Inorg. Chem. 1978, 17, 3521.
0020-1669/82/1321-3123$01.25/0
A total of 2833 unique reflections with 0 < 20 5 50" were collected with use of the 8-28 scan technique, variable scan rates from 4.0 to 24.0°/min, and a scan range from 28(Mo Ka,)- 0.8" to 28(Mo Kaz) 0.8". The intensities of 3 standard reflections monitored after every 100 reflections showed a gradual decrease of about 10% during data collection, so a decay correction was applied. Data were also corrected for Lorentz and polarization effects, but an absorption correction was not necessary (linear absorption coefficient p = 7.13 cm-I). S2P4(NMe)6. Solution and Refinement of the Structure. The positions of all phosphorus, sulfur, and nitrogen atoms were obtained from an E map. This map was generated by using as a starting phase set the one with the highest figure of merit produced by the program MULTAN operating on an input of the 315 reflections with E values greater than 1.60. These positions were used to phase a Fourier difference map, from which all the carbon atoms were located. Three cyles of least-squares refinement of a scale factor, all positional parameters, and isotropic temperature factors gave the discrepancy indices
+
R1 = CIIFoI - lFcll/lFol= 0.123 Only those 2213 reflections with F: I347:) were included in the refinement. Atomic scattering factors were those for neutral atoms with anomalous scattering terms included for all atoms. The function minimized during all least-squares refinements was cw(lFol where the weighting factor is w = ~F:/CT(F,~)~.A value of 0.07 was used for p in the calculation of u. Three least-squares cycles refining the scale factor, positional parameters, and anisotropic temperature factors reduced RI to 0.053 and R2 to 0.091. The largest parameter shift on the last cycle was less than 0.10 times the estimated standard deviation. The esd of an observation of unit weight was 2.102. A final Fourier difference map contained only peaks due to hydrogen atoms. S3P4(NMe)@Data Collection. A crystal was ground to a sphere -0.35 mm in diameter and mounted, in a sealed capillary, on the Syntex P i diffractometer. Proceeding as above for the dithio compound, we found the space group to be Pbca and the following unit cell dimensions were measured: a = 9.839 (4) A, b = 13.383 (7) A, c = 25.839 (10) A, V = 1602 (1) A3, dcald= 1.54 g/cm3 for Z = 8, and a molecular weight of 394.26. Absorption corrections were omitted since p = 7.9 cm-' for Mo K a radiation and the crystal was spherical. Three standard reflections measured after every 150 data points fluctuated randomly by *4%. Of 3255 reflections measured
(5) Riess, J. G.; Wolff, A. J . Chem. Soc., Chem. Commun. 1972, 1050. Wolff, A.; Riess, J. G.; Bull. Soc. Chim. Fr. 1973, 1587. Casabianca, F.; Pinkerton, A. A.; Riess, J. G. Inorg. Chem. 1977, 16, 864.
0 1982 American Chemical Society
Cotton et al.
3124 Inorganic Chemistry, Vol. 21, No. 8, 1982 Table I. Positional Parameters for S,P4(NMe),a atom X V S(1) S(2) P(1) P(2) P(3) P(4) N(1) N(2) N(3) N(4) N(5) N(6) C(1) C(2) C(3) C(4) C(5) C(6)
0.6605 (1) 0.4302 (1) 0.66751 (9) 0.29880 (11) 0.06333 (11) 0.17358 (11) 0.2770 (3) 0.0686 (3) 0.6676 (3) 0.1885 (4) 0.2867 (3) 0.0757 (3) 0.8032 (4) 0.9594 (4) 0.7150 (5) 0.1909 (6) 0.3841 (5) 0.9781 (5)
0.0970 (1) 0.3312 (1) 0.16962 (9) 0.29479 (10) 0.29791 (11) 0.12445 (10) 0.3584 (3) 0.3573 (3) 0.2952 (3) 0.3227 (3) 0.1720 (3) 0.1721 (3) 0.0297 (4) 0.3713 (4) 0.3409 (4) 0.3001 (6) 0.1072 (5) 0.1096 (5)
Table 11. Positional Parameters for S,P,(NMe),= atom
Z
0.2313 (1) 0.2609 (2) 0.0612 (1) 0.3331 (1) 0.2811 (1) 0.4363 (2) 0.4786 (4) 0.4403 (4) 0.0776 (4) 0.2318 (4) 0.3685 (5) 0.3245 (5) 0.9753 (6) 0.4860 (5) 0.2083 (6) 0.0797 (5) 0.4021 (8) 0.3112 (10)
a Estimated standard deviations in the least significant digits are shown in parentheses.
Ti'
S(1)
S(2) S(3) P(1) P(2) P(3) P(4) N(1) N(2) N(3) N(4) N(5) N(6) C(1) C(2) C(3) C(4) C(5) C(6)
X
0.6581 (5) 0.2831 (5) 0.1102 (4) 0.5241 (3) 0.3422 (3) 0.2594 (3) 0.4737 (3) 0.4535 (8) 0.2193 (8) 0.3818 (10) 0.5765 (8) 0.4127 (9) 0.3374 (9) 0.429 (1) 0.082 (1) 0.413 (2) 0.726 (1) 0.475 (1) 0.301 (1)
Y 0.3868 (3) 0.0946 (4) 0.2955 (3) 0.2837 (2) 0.1436 (3) 0.2398 (2) 0.0865 (2) 0.2380 (6) 0.1941 (7) 0.3204 (6) 0.1843 (6) 0.0597 (6) 0.1443 (7) 0.3169 (11) 0.1413 (15) 0.3991 (11) 0.1567 (10) -0.0325 (9) 0.1117 (8)
Z
0.1431 (2) 0.2487 (1) 0.0492 (2) 0.1322 (1) 0.1831 (1) 0.0867 (1) 0.0846 (1) 0.1865 (3) 0.1456 (3) 0.0989 (3) 0.0992 (3) 0.1462 (3) 0.0581 (3) 0.2287 (5) 0.1506 (6) 0.0545 (6) 0.1003 (5) 0.1712 (5) 0.0038 (4)
a Figures in parentheses are the estimated standard deviations in the least significant f i r e s .
Table 111. Selected Bond Distances (A) and Angles (Des) in S,P,(NCH,),
Figure 1. The S2P4(NMe)6molecule, showing the atom numbering scheme. Each atom is represented by its ellipsoid of thermal vibration scaled to enclose 50% of the electron density.
S(l)-P(l) S(2)-P(2)
1.920 (1) 1.913 (1) 1.916 (5) 1.706 (3) 1.691 (3) 1.699 (10) 1.732 (3) 1.717 (3) 1.741 (3) 1.736 (3) 1.732 (10) 1.504 (4) 1.493 (4) 1.485 (4) 1.514 (4)
P(l)-N(2) P(l)-N(3)
1.676 (3) 1.654 (3) 1.673 (3) 1.657 (3) 1.665 (11) 1.695 (3) 1.689 (3) 1.692 (4) 3.003 (1) 3.003 (1) 2.955 (1) 2.966 (1) 2.962 (1) 2.959 (1) 2.961 (5)
N(5)-C(5) N(6)-C(6) N-C (av)
(4) 1'472 (4) 1.495 (15)
P(l)-P(2) SP-PS (av)
2.921 (1) 2.921 (1)
P(l)-N(l)-P(2) P(l)-N(2)-P(3) P(l)-N(3)-P(4)
1
Figure 2. The S3P4(NMe)6molecule, showing the atom numbering scheme. The methyl carbon atom C(5) lies below (and is bonded to) N(S), but it is covered by other atoms. Each atom is represented by its ellipsoid of thermal vibration scaled to enclose 50% of the electron density. in the range 0 < 2 8 I 50" with graphite-monochromated Mo Ka radiation 1379 had Z > 3 4 and were retained and used. S,P4(NMe)6. Solution and Refmment of the Structure. Positional parameters for two of the three sulfur atoms and the four phosphorus atoms were derived from an E map, on the basis of the phase set derived from the 250 highest E s and having the highest figure of merit, and computed from an adapted version of MULTAN. A difference
119.35 (16) 120.25 (15) 121.71 (16)
P(4)-N(5)-C(5) P(3)-N(6)4(6) P(4)-N(6)4(6)
121.46 (17) 124.23 (18) 121.5 (16) 114.3 (2) 114.3 (2) 117.5 (2) 111.0 (2) 118.8 (2) 113.1 (2) 116.6 (3) 109.5 (3) 120.4 (3)
P(2)-P(l)-P(3) 44) P(3 )-P( 1)-P(4) P(l)-P(2)-P(3) 44) P(3)-P(2)-P(4) P( l)-P(3)-P(2) P( 1)-P(3)-P(4) P(2)-P(3)-P(4) P(l)-P(4)-P(2) -R3) P(2)-P(4)-P(3) P-P-P (av)
113.2 (3) 117.3 (3) 114.0 (3) 115.0 (25) 60.54 (3) 60.35 (3) 60.95 (3) 60.30 (3) 60.57 (3) 60.95 (3) 59.16 (3) 59.69 (3) 59.48 (3) 59.07 (3) 59.35 (3) 59.57 (3) 60.0 (6)
electron density map following least-squares refinement of the positional and iostropic thermal parameters for these six atoms revealed the positions of the remaining non-hydrogen atoms of the asymmetric unit. All atoms were first refined by employing isotropic thermal parameters and then using anisotropic thermal parameters (using p = 0.06 in assigning weights) to give the final residuals R , = 0.074 and R2 = 0.105, with no parameter shift exceeding 5% of its esd in the final cycle. Attempts to locate hydrogen atoms following the anisotropic refinement were unsuccessful, owing most likely to rotational disorder of the methyl groups. The final difference map was devoid of chemically significant features.
Inorganic Chemistry, Vol. 21, No. 8, 1982 3125
closo-Tetraphosphorus Hexakis(methy1imide)
C
Table IV. Bond Distances (A) and Bond Angles (Deg) in S3P4(NMe),a-C S(1)-P(l) S(2)-P(2) S(3)-P(3) S-P (av) P(4)-N(4) -N(5) -N(6) P-NPS (av) P(l)-N(4) P(2)-N(5) P(3)-N(6) SP-NP (av) P( 1)-N ( 1) -N(3) P(2)-N(1) -N(2) P(3)-N(2) -N(3) SP-NPS (av) P( 1)-N( 1)-P(2) P(2)-N(2)-P(3) P( l)-N(3)-P(3) P( l)-N(4)-P(4) P(2)-N(5)-P(4) P(3)-N(6)-P(4) P-N-P (av) C(1)-N(1)-P(1) -P(2) C(Z)-N(2)-p(2) -P
