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The stereochemistry of quaternary N-methyl sparteinium cations, their derivatives, stereoisomers and analogues
Journal of Molecular Structure, 160 (1987) 189-208 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands
THE STEREOCHEMISTRY OF QUATERNARY N-METHYL SPARTEINIUM CATIONS, THEIR DERIVATIVES, STEREOISOMERS AND ANALOGUES Part II. Molecular and crystal structure, and IR spectra of methiodide and methperchlorate of Z-oxosparteine
U. MAJCHRZAK-KUCZYNSKA Institute of Organic Chemistry, Academy
of Economics,
PoznaA (Poland)
A. E. KOZIOL Institute of Chemistry, M. Sklodowska-Curie
University, Lublin (Poland)
M. WIEWICROWSKI Institute of Biooqanic (Received
Chemistry, Polish Academy
of Sciences, Poznah (Poland)
1 October 1986)
ABSTRACT The crystal and molecular structures of two quaternary salts of 2-oxosparteine (II), the methiodide (IICH:* I-) and the methperchlorate (IICHz* ClO;) have been determined on the basis of X-ray and IR data. The studies were performed by analogy to previously investigated quaternary salts of sparteine (I), the methiodide (ICHin I-) and the methperchlorate (ICH;. ClO;). As expected, the configurations and conformations of cationic parts within the two pairs of quaternary salts are identical, except for the structure of their A/B fragments, which in ICH: cations have the character of tertiary amines, but in IICH: that of la&ems. On the basis of accumulated X-ray and IR data the similarities and differences in the modes of interaction of perchlorate and iodide anions with quaternary cations, and especially with their N*-CH, groups are discussed. In this discussion are also included the methiodide and methperchlorate of ol-isosparteine: IIICH:. X- (X- = I- or ClO;) where N+-CH, groups are cisoidally oriented to the basic nitrogen atoms. The most interesting observations are as follows: (i) When N+-CH, groups are easily accessible for direct quasi hydrogen bonding interactions with counter anions and when other positive charged groups, for instance lactam groups, are absent in quaternary cations, perchlorate anions interact more” strongly than the iodide anions and in consequence introduce conformational changes into the ring with N+-CH, group as well as into further rings. (ii) Perchlorate and iodide anions interact with N+-CH, groups similarly and very weakly if at all, when the N+--CH, groups are for steric reasons inaccessible to counter anions or when in quaternary cations there are additional groups which attract the counter anions electrostatically. The last mechanism operates in both quaternary salts of 2-oxosparteine and this is the reason why their monocrystals are isosteric and IR spectra almost identical. (iii) The sterically hindered N’-CD, groups in both IIICDi* X- salts give rise in their IR spectra to two doublets of sharp, well resolved bands which indicate the presence of two different rotamers stabilized by two modes of weak intramolecular hydrogen bonds with 0022-2860/87/$03.50
0 1987 Elsevier Science Publishers B.V.
190
basic N atoms. (iv) In IIICH:* X- and IIICD:. X- salts the perchlorate and iodide anions do not interact at all with the rotating and vibrating N+-CH, (N+-CD,) group but the structures of these salts are not isosteric since the perchlorate anions interact more strongly than iodide anions with the A/B fragment of the IIICH: cations. This is visible from the shapes and intensities of the so-called “tram” band in the IR spectra of both salts. INTRODUCTION
Rejection of the incorrect structures of sparteine-iV( 16)-methiodide and sparteine-l\r( 16)-methperchlorate (ICH,‘* I-, ICH:* CIO;) [l-3] and the determination of the correct ones, logically resulted in a revision of erroneous interpretations of the vibrational spectra of these compounds [4]. Next, a new determination of the structure and spectroscopic properties of 2-0x0sparteine-iV( 16)-methiodide and 2-oxosparteine-N( 16)-methperchlorate (IICH:* I:, IICH:* ClO,) was undertaken; this issue is the subject of the present paper. Although an easy and efficient transformation of 2-oxosparteine (II) into sparteine (I) and IICH$- ClO, into ICHl* ClO; could be sufficient proof of analogous molecular conformations of both quaternary salts of I and II (Scheme l), we wanted to exclude completely the possibility of isomerization in the course of the reduction of IICH,‘- X- to ICH,‘. X- (X = I- or ClO;). For this reason single crystals of IICH:* I- and IICHf- ClO, were subjected to X-ray analysis. As in the case of two quaternary salts of I [4], simultaneous studies on molecular and crystal structures of IICHS- ClO, and IICH;* I- were aimed at tracing the influence of perchlorate and iodide anions on the fine differences in the deformations of the four coupled heterocyclic rings. In ICHg* X- four piperidine rings were found, forming two tram quinolizidine systems: A/B, double chair with tertiary nitrogen atom; and C/D, boat-chair with quaternary nitrogen atom. On the other hand, in quaternary salts of the type IICH:* Xthe A/B rings form a truns quinolizidone system probably within a sofa-chair conformation as in IIHClO,,* Hz0 [ 51. In short, the present paper should answer two questions: (1) whether the configuration and conformation of the C/D fragments of ICH:- X- and IICH:. X- are analogous, and (2) whether the structural and chemical differences between the A/B fragments of these cations (a basic double chair tram quinolizidine system with tertiary nitrogen atom in the case of I; a neutral sofa-chair tram quinolizidine system with a lactam group in the case of II) significantly influence the complex interactions between methquinolizidine quaternary cations and the ClO; and I- counter anions.
191
CH,I I
ICi-lfX
x=i;cl& scheme
1
EXPERIMENTAL
Materials 2-Oxosparteine methiodide (IICHd* I-) 6.2 g 2-oxosparteine (II) were dissolved
in 50 ml methyl iodide, and the solution stored in darkness at room temperature. After a few minutes, the first crystals began to appear in the colourless solution. The reaction was over within four days, and proceeded with nearly 100% efficiency. The well grained crystals which were obtained (first crop, 7.71 g; second crop, 0.92 g) were recrystallized in methanol. M.p. = 281-285°C (decomp.); [LX]ho = +54.0 (HzO, c = 1). Elemental analysis was in agreement with the formula C16H27NZOI.
192
Deuterated analogue of 2-oxosparteine methiodide (IED; * I-) 0.26 g 2-oxosparteine (II) was dissolved in 5 ml acetone and 0.63 ml CDJ
was added. The reaction was completed after three days. 0.36 g colourless crystals was obtained. Elemental analysis was in agreement with the formula C~~H~QD~N~CI. 2-Oxosparteine methperchlorate (IED: * CZO4)
(IICH:
* (30,)
and its deuterated
analogue
These compounds were obtained by the exchange of the iodide anion in IICH,‘. I- and IICD;* I- for a perchlorate anion using a Dowex column. Normal and deuterated methperchlorates of ac-isosparteine (III) were obtained similarly (IIICH: - ClO, and IIICD: 0 CIO;). IR analysis
IR spectra were measured on a Perkin-Elmer 180 spectrophotometer the suspension technique in Fluorolube and Nujol. X-Ray structure
using
determination
The crystals were obtained by recrystallization from methanol solutions. Crystal data for both salts are summarized in Table 1. Intensities of Bragg reflections were collected on a Syntex P2, four-circle diffractometer using graphite monochromatized MO Kol radiation. No background measurements were made; the Lehmann and Larsen [6, 71 method was applied to calculate the intensity of each reflection from a peak profile. Intensities were corrected for Lorentz and polarization effects. Both structures were determined in a similar way: first, Patterson synthesis was calculated for determination of I or Cl atom position, and then subsequent Fourier maps gave C, 0 and N atoms. Experimental details and results of the refinement are shown in Table 2. TABLE 1 Crystal data IICH; . IFormula Crystal system Space group Unit cell parameters a (A) b (A) c (A) P (deg.) v (A3) z D, (g cm-%)
lG&N,Ol+I-
IICH; . ClO;
t%H,,N,Ol+C10;
monoclinic p2,
monoclinic p2,
7:780(2) 15.398( 2) 7.377( 2) 108.69(2) 837.1(2) 2 1.55
7.882( 2) 15.682( 2) 7.456( 1) 107.80( 1) 877.4( 3) 2 1.37
193
Calculations were performed on a NOVA 1200 minicomputer with a Syntex XTL system [8]. The atomic scattering factors were taken from the International Tables for X-Ray Crystallography [9]. RESULTS
Final coordinates and isotropic temperature factors are given in Tables 3 and 4. Bond lengths and angles as well as torsion angles for cations of both salts are collected in Table 5. The conformation of the methyl 2-oxosparteine cation is illustrated in Fig. 1.
Fig. 1. The conformation cation (IICH:).
and atom numbering scheme of N-methyl-2-oxosparteinium
TABLE 2 Experimental conditions and results of least squares refinement
Crystal dimensions (mm) ~(Mo Kol)(mm-l) 20 Range (deg.) Scan mode Scan width (deg. min’) Range of transmission factors for absorption corrections hkl Range Number of reflections measured used in the final refinement (I > 1.960(Z)) Number of refined parameters R = ~(AF(/zF, R, = [x w(A F)Z/cw(F,)Z]"Z w ifF, < 4.5 if 4.5 < F, =Z53 if F, > 53 Goodness of fit c [w(F, - F,)* l”2/(N, - N,) H atoms
IICH; . I-
IICH; * CIO;
0.35 x 0.4 x 0.5 1.94 O-48 e/2e 2.0-29.3 0.66-1.00
0.5 x 0.45 x 0.55 0.25 O-52 .9/2&J 2.0-29.3 Not applied
0.08-8,
009~-8,19,9
17, 8
1361 1269
1497 1362
180 0.039 0.040 (F0l4.5)’
216 0.063 0.059 l/o’(F)
(153/F,). 3.52
4.98
19 found in D map; 8 with positions calculated
27 in positions calculated from geometry of cation
194 TABLE3 Non-hydrogenatom coordinates (X 104;x lo5 forI atom)and& Y
x
IICH;.II N(1) C(2) 0 C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(l0) C(l1) C(12) C(13) C(14) C(15) N(16) C(17) C(18) IICH;.ClO; Cl O(1) O(2) O(3) O(4) N(1) C(2) 0 C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(l0) C(l1) C(12) C(13) C(14) C(15) N(16) C(l7) C(18)
= 1/3XBi,(A') Bw
z
5076(7) 6910(g) 7840(g) 7765(11) 6651(11) 4725(11) 3872(g) 1969(g) 1257(9) 2441(12) 4317(9) 2663(10) 2504(12) 2953(12) 1815(4) 2006(10) 1452(8) 1861(10) -564(10)
25000(O) 272(4) 157(5) 20(5) 208(7) 673(6) 343(6) 538(5) 145(5) 410(5) -68(7) 360(5) -1043(5) -1597(6) -2512(11) -2892(6) -2315(6) -1380(4) -845(6) -1393(6)
12137(9) 6838(8) 7604(11) 6577(10) 9735(12) 10795(11) 10047(11) 7935(10) 7068(10) 4984(11) 3999(12) 4750(10) 4394(11) 2666(12) 3181(12) 4399(14) 6094(11) 5525(9) 7342(11) 4408(12)
5.64(6) 2.1(4) 2.3(5) 3.6(5) 3.6(7) 3.3(6) 3.1(6) 2.3(5) 2.4(6) 2.4(5) 2.2(6) 2.3(5) 2.4(5) 3.3(6) 5.0(8) 4.2(8) 3.4(8) 2.3(5) 2.7(6) 3.1(6)
7697(3) 9072(12) 6691(14) 6683(19) 8362(20)
7500(O) 8049(6) 7355(11) 7781(10) 6748(8)
8903(3) 9074(12) 7191(14) 9914(20) 9543(25)
4.8(2) 13.0(12) 18.7(19) 24.6(21) 21.3(22)
5236(4) 5173(4) 5079(4) 5221(5) 5643(5) 5291(5) 5505(4) 5134(5) 5407(4) 4933(4) 5314(4) 3968(4) 3419(5) 2472(6) 2161(5) 2712(4) 3655(3) 4177(4) 3688(5)
3095(6) 2354(8) 3372(7) 236(10) -819(g) -122(9) 1973(8) 2830(g) 4885(g) 5900(8) 5162(8) 5469(8) 7236(g) 6751(10) 5558(11) 3840(g) 4398(6) 2564(8) 5447(10)
2.5(3) 2.8(5) 4.2(4) 4.0(6) 3.9(6) 3.8(6) 2.7(5) 2.9(5) 3.1(5) 2.7(5) 3.0(5) 2.8(5) 3.7(6) 5.0(6) 4.4(6) 3.7(6) 2.4(3) 3.2(5) 3.6(6)
22829(g)
4736(6) 2941(8) 1987(6) 2081(g) 3248(10) 5090(10) 5927(8) 7819(8) 8478(g) 7338(8) 5464(8) 7168(8) 7393(9) 7046(10) 8141(11) 7929(9) 8412(6) 7993(9) 10374(8)
195 TABLE
4
Hydrogen
atom
coordinates IICH;
Atom
x H(31)a H(32)a H(41) H(42) H(51)a H( 52)a H(61)a H(71)a H(81)a H(82)” H(91)a H(lOl)a H( 102) H(lll)a H(121)a H( 122)a H(131)” H( 132) H(141)a H( 142)a
779 922 667 715 421 470 346 139 134 1 193 504 426 384 346 115 433 268 25 206
H(151)” H(152)a H(171) H(172) H(181) H( 182)a H(183)
130 313 306 89 -98 -65 -133
aAtom
position
(X
103) Biso = 5.0 AZ for all hydrogen-atoms
- I-
Atom Y -43 49 131 56 65 -34 115 34 114 32 2 8 100 -115 -135 -173 -249 -292 -300 -354 -250 -240 -105 -97 -79 -191 -154
z
IICH; . ClO; X
1013 1018 1055 1219 1083 1037 769 781 501 446 253 412 449 500 192 154 393 201 330 520 703 700 823 793 375 328 525
H(31) H(32) H(41) H(42) H(51) H(52) H(6) H(7) H(81) H(82) H(9) H( 101) H(102) H(l1) H(121) H(122) H(131) H( 132) H( 141) H( 142) H( 151) H( 152) H( 171) H( 172) H(181) H( 182) H( 183)
180 95 271 326 506 584 605 860 978 836 791 466 551 618 865 655 736 577 947 782 874 668 685 897 1050 1100 1100
Y 463 555 551 627 465 555 613 537 525 604 499 500 593 402 349 362 213 239 216 156 249 267 396 408 350 325 425
2 -24 -2 -220 -63 -30 -86 205 214 544 498 728 575 552 427 811 790 795 605 632 512 313 304 170 201 650 550 550
from D map.
Structure factor lists and anisotropic thermal parameters for non-H atoms are deposited with the British Library Lending Division as Supplementary Publication No. 26331 (15 pp.). IR spectra in the range 3200-1500 cm-’ and 1500-400 cm-’ for eight salts: IICH;. X-; IICD; * X-; IIICH: X-; IIICD: * X- (X- = I-, CIO,) are presented in Figs. 2, 3 and 4. l
DISCUSSION
The X-ray analysis of IICH: - I- and IICH; - ClO, performed in the course of our studies unequivocally proved the tram configuration of the quinolizidine C/D fragment of both compounds, as had been previously determined [4] for cations of sparteine quaternary salts (ICH;. X-). In the IICH: cation
196 TABLE5 Molecular geometry Parameter Bond length(A) N(lW(2) N(l)-C(6) N(l)-C(lO) C(2)--0 C(2w3) C(3)+(4) C(4)+(5) C(5W(6) C(6)--c(7) C(7)--C(l7) C(7)-+(8) C(8)--C(9) C(9)--C(lO) C(9)-C(ll) c(11)-c(12) C(ll)--N(16) C(l2wl3) C(13)-C(14) C(14)-C(15) C(15)--N(16) N(16)--C(17) N(16)-C(18)
IICH;*I-
1.367(10) 1.478(9) 1.469(9) 1.222(10) 1.500(11) 1.520(13) 1.510(3) 1.514(11) 1.536(11) 1.543(12) 1.514(11) 1.532(12) 1.534(12) 1.529(13) 1.506(11) 1.535(10) 1.472(9) 1.563(15) 1.502(13) 1.523(11) 1.518(10) 1.520(10)
IICH;*ClO;
1.356(8) 1.497(8) 1.476(8) 1.230(8) 1.518(10) 1.531(10) 1.491(10) 1.535(10) 1.545(8) 1.527(10) 1.521(10) 1.531(9) 1.532(9) 1.544(9) 1.539(10) 1.523(8) 1.532(12) 1.498(11) 1.511(11) 1.552(8) 1.540(8) 1.506(8) 1.36(1 1.30(1 1.33(2 1.32(1
Cl-o(l) Cl-O(2) Cl-O(3) Cl-O(4) Bond angles (deg.) C(2k---N(1)-c(6)
C(2)-N(l)-C(lO) C(G)-N(l)-C(lO) N(l)--C(2)--C(3) N(1)-%(2)-0 0-C(2)-C(3) C(2)--C(3W(4) C(3)-C(4)--C(5) C(4)-C(5)-+(6) C(5)--c(6)--c(7) C(5)--c(6)-N(1) C(7)-C(6)-N(1) C(6)-C(7)--C(17) C(6)--C(7)-C(8) C(17)-C(7)-C(8) C(7)-C(8)-C(9) C(8)-C(9)--C(lO) C(8)--C(9)--c(ll)
124.7(6) 117.4(6) 115.9(6) 118.7(7) 120.8(7) 120.5(7) 115.4(7) 108.4(7) 111.5(7) 113.3(6) 111.3(6) 111.0(6) 114.8(6) 107.8(6) 112.4(6) 105.8(6) 105.6(7) 115.4(7)
123.2(4) 117.1(5) 116.8(4) 119.9(5) 121.0(5) 119.0(5) 114.1(5) 109.6(6) 110.1(5) 113.5(5) 111.1(5) 110.7(4) 115.5(5) 107.4(5) 113.0(5) 106.9(5) 106.3(5) 113.6(5)
197 TABLE
5 (continued) IICH;
c(10)-C(9)-+(11) C(9)-C(lO)-N(1)
108.5(7) 110.8(6) 114.9(7) 112.6(6) 111.7(6) 112.0(8) 112.1(9) 109.5(8) 112.7(7) 106.8( 6) 111.9(6) 114.6(6) 107.5(6) 107.7(6) 108.0(6) 115.2(6)
107.1(5) 111.5(5) 113.0(5) 113.4(5) 110.1(5) 112.0(6) 111.2(6) 112.5(6) 111.3(5) 107.5(5) 110.5(5) 116.1(4) 107.7(4) 107.3(4) 107.4(5) 114.2(5)
-19.9( 10) 46.5( 10) -61.8( 10) 49.0(8) -21.5(9) 7.0( 10)
-20.3(7) 46.1(7) -62.7(7) 52.3(6) -26.7(6) 11.1(7)
N(l)--C(6)+x7)--C(8) C(6)+?7)+J8)--c(9) C(7)-c(8)-c(9)-c(lO) C(8)+(9)+YlOk--N(1) C(9)-C(lO)-N(l)-C(6) C(lO)-N(l)-C(6)+(7)
-55.6(9) 68.0(S) -69.8( 8) 60.1(9) -50.5(8) 47.6(8)
-55.0(6) 68.3(6) -69.1(6) 57.5(6) -47.9(6) 46.1(6)
Ring C C(7)-C(17)-N(16)-C(ll) C(17)-N(16)--C(ll)-C(9) N(16)-C(ll)-C(9)-C(8) C(ll)-C(9)-C(8)-C(7) C(9)-+?(8)-C(7)-C( C(8)-C(7)-C(17)-N(16)
45.6(7) -55.1(8) 7.0(8) 50.1(8) -59.6( 9) 12.1(6)
46.0(6) -57.4(5) 9.8(6) 48.4(6) -60.2(6) 12.3(5)
56.6( 10) --53.1(12) 53.8(12) -57.2( 9) 57.7(8) -58.9(9)
56.9( 7) -52.3(7) 52.6(8) -57.4(7) 59.5(6) -58.9(9)
C(9)--c(ll)-C(l2) C(9)-C(ll)-N(16) C(12)-C(ll)-N(16) C(ll)-C(12)-C(13) C(12)--C(13)-C(14) C( 13)--q 14)--q C( 14)-C( 15)-N( C(lS)-N(16)+(15) C(18)-N(16)-C(17) C(18)--N(16)--C(ll) C(ll)-N(16)<(15) C(ll)-N(16)+(17) C(17)-N(16)+(15) C(7)-C(17)-N(16) Torsion
angles
15) 16)
* I-
IICH; . ClO;
Parameter
(deg.)
Ring A N(1)--C(2)_-C(3)--C(4) C( 2)-C( 3)-C(4)-C(
5)
C(3)-C(4)~(5)-C(6) C(4)-C(5)-C(6)-N(1) C(5)-+(6)-N(l)-+(2) C(6)-N(l)--C(2)-+?3) Ring B
17)
Ring D N(16)-C(15)-C(14)-C(13) C(15~C(14)-C(13)--C(12) C(14)--C(13)-C(12)-C(11) C(13~C(12)--C(ll)-N(16) C(12)--C(ll)-N(16)-C(15) C( ll)-N( 16)-C( 15)X(
14)
198 TABLE
5 (continued) IICH;
* I-
IICH; . ClO;
External 0-C( 2)-N( 1)-C(6) O-C(2)-C(3)-C(4) O-C(2)-N(l)-C(lO) C(18)--N(16)--C(15)-C(14) C(18)-N(16)-C(ll)-C(12) C( 18)-N( 16)-C( ll)-C( C(18)--N(16)-C(17)--C(7)
-172.8(11)
-168.7(7) 159.5(7) --8.7(7) 66.1(6) -61.1(6) 66.6( 6) -81.5(5)
159.9(10) -9.4( 11) 64.5(7) -60.9( 8) 9)
70.2(7) -81.3(7)
particular rings occur in the following conformations: ring A, deformed halfchair; ring B, chair; ring C, deformed boat; ring D, chair (Fig. 1). Comparison of the geometries of the cationic fragments of both salts (IICH:. X-) made using the BMFIT programme [lo], shows them to be almost identical (the sum of standard deviations squared between atom pairs equals Zu2 = 0.856 a”). A detailed conformational analysis using asymmetry parameters [ll] is presented in Table 6. Comparing the values of these parameters for the C rings, in which the methylammonium groups are located in ICH: and IICHS cations, it can be seen that a boat conformation significantly and similarly deformed is present in the three following cations: IICHS * I-, IICH,‘. ClO, and ICH: - ClO,. In turn, ring C possesses well preserved boat conformation symmetry elements in the cation of I,,SCH:. I- [4]. The very similar and strongly deformed boat conformation of ring C within both quaternary salts of 2-oxosparteine (IICHS * X-) seems to indicate that in these cases counter anions have no influence on the degree of deformation of the C-ring conformation since pronounced repulsion forces act between N6’(1) and N’(16) atoms which are respectively partly or fully positively charged. Comparison of the distances between N(1) and N(16) in the four quaternary salts considered (ICH; * X- and IICH: X-) fully verify the above statements (see Table 7). In both quaternary salts of compound II this distance is longer by 0.1 a than that in analogous salts of I, where the nitrogen atoms at the A/B ring are basic and not lactamic in character, and in consequence attract instead of repel the positively charged methylammonium N( 16) atoms. The crystals of both IICH: - I- and IICH: - ClO; are isostructural, as illustrated in Fig. 5. Upon comparison of the packing of the ions in crystals, one can state that the I- and ClO, anions “substitute” each other. The distances between the centre of the anion (I, Cl; symmetry code (i) in Fig. 5) and atoms N( 1) and N( 16) of the car-ion are compatible in both structures (Fig. 5). However, the environment of the 3N+--CH3 group is somewhat different. Weak electrostatic interactions of the sN+--CH3 group with two I- anions are observed in methiodide, whereas in methperchlorate only the weaker van der Waals type of interactions between the ClO, anion and cation are present. l
199
Probably the above small differences within weak interactions of I- and ClO; anions with the same IICH; cations are expressed by a shortening by 0.021 A of the N(l)*** N( 16) distance in IICH:* I-, in comparison with that present in IICH3 - ClO; (see Table 7). As stated above, the average N( 1). * - N( 16) distances within both sparteine quaternary salts (ICH:* X-) are significantly shorter (by 0.1 A) than in analogous quaternary salts of II, since in the ICH: cation a weak electrostatic attraction exists between basic N(1) and positively charged N(16). In consequence, the boat conformation of ring C in ICH: - I’ is almost ideal since very polarizable iodide anions form a set of hydrogen bonds around quaternary N(16) atoms which stabilize that conformation. In the case of ICH:* ClO,, the perchlorate anion forms two geminal hydrogen bonds with the N+(16)CH3 group which significantly deform the boat conformation of ring C and in consequence the stretching vibrations of C(lO-H and C(6)-H bonds (see Fig. 5 of ref. 4). The question still remains as to why the proton acceptor activity of ClO; anions towards IICHS cations is so weak that it can be neglected, whereas towards the ICH; cations it is significant and deforms the boat conformation of ring C. Assuming that repulsive forces operating between N(1) and N(16) in IICH: cations are responsible for a pronounced deformation of the boat conformation of ring C, but not for decreasing the proton donor activities of the N’(16)-C-H bonds, there seems to exist only one reasonable explanation; that the dipole of the lactam group in IICH: electrostatically attracts the Cl04 anions more strongly than I- anions. Such an assumption is fully justified, since the dimensions and geometry of the ClO, anion could enable it to approach more easily than I- anion the positive end of the lactam group located inside the IICHS cation. In consequence the concentration of ClO; anions around the quaternary N(16) atoms of IICH: is significantly diminished, causing an increase in the distance between cation and anion (see Table 8). In summary, we can say that different dimensions, geometries and polarizabilities of ClO, and I- anions are responsible for differences in hydrogen bonding and electrostatic interactions between cationic and anionic fragments within the pairs of quaternary salts ICH: * I--1CHS - ClO, and IICH: * I’ IICHS * CIO,. In the first pair both anions form relatively strong hydrogen bonds but different organizations with the quaternary N+(lG)-CH3 groups, whereas in the second pair these anions interact very weakly and similarly with the N’( 16)~-C!H3 cationic fragments, since they are additionally involved in different weak electrostatic interactions with lactam groups. The consequence of this distribution of weak electrostatic interactions of I- and (30, on two positively charged centers of the IICHS cation (located at the quaternary N( 16) atom and lactam group atoms C( 2) and especially N( 1)) is that the crystals of IICHf * X- (X- = I- or (30,) are isostructural. X-ray structural conclusions are in very good agreement with spectroscopic
200
I I
3000
2000
2500
1KJO
1800
cm-’
Fig. 2. IR spectraof 1500
cm-’
IICH;.
(Fluorolube).
I-, IICD:.
I-; IICD:.
ClO;
and IICDi-
ClO;
in the range 3200
201
:
* ‘,
1400
lZcfl
,:
800
loo0
&lo
400
cm-’
Fig. 3. IR spectra of IICH,+* I-, IICD,+* I-, IICD, +. ClO; 1400 cm-’ (Nujol).
and IICD:.
CTO; in the range 1500-
I 3000
2500
2ooo
Fig. 4. IR spectra of IIICHlI-, 3200-1500 cm-’ (Fluorolube).
IIICD:I-,
1800
1600cm"
1IICH:ClO;
IL00
and
IIICH;CD,ClO;
data (Figs. 2 and 3). The IR spectra of normal and crystalline preparations within the pair IICHf- I- and tical in very many points indicating that the structures identical. Some differences can be observed in those bonds of vcFo (from ClO;) occur. Differences in
in the range
selectively deuterated IICHl* ClO, are idenof the cations are also fragments where the the region of Vo-_H
203 TABLE
6
Asymmetry
parameters IICH;
- I-
IICH;
2.1 38.6 41.9 17.8
6.3 38.6 41.8 13.8
19.9
21.7
AC;
3.3
1.8
Ac;,~
6.6
9.1
15.7 13.4 12.4
12.1 12.8 14.5
AC5 A@ AC;
AC& AC;,' AC;
- I-
IICH;
- ClO;
AC;
8.3
15.9
Ac9’” s
10.5
11.9
AC;
31.6
29.6
AC;,'
38.3
36.2
AC’%‘3
3.0
4.0
AC)
3.6
5.0
AC”,‘2
4.9
7.2
0.9 2.3 3.6
0.3 3.4 5.3
Ring D
Ring B AC;*'
IICH;
Ring C
Ring A AC;.'
- ClO;
AC)
AC’%‘4 A$
2300-2100 cm-‘, are (fN+-CH3) 3080-2970 cm-’ and vc_,, (fN+-D3) very much smaller than those in spectra of ICH:* I- and ICHS* ClO, [4]. X-ray analysis indicates that such a situation is due to a markedly weaker interaction of the anions with the acidic hydrogen atoms of the >N+-CH3 groups in IICH:. X- than in analogous salts of I (distances I-(Cl-). lCH,-N’(16) for ICH,‘. I-, ICH:. ClO,, IICH,‘. I- and IICH:. ClO; are 4.04(l); 3.99(l); 4.230(g); 4.395(8) a respectively (see Tables 5 and 7 in ref. 4). As has already been stated, cationanion electrostatic contacts in quaternary IICH: * I- and IICH: * CIO; salts are weak, although in methiodide the contacts are closer than in methperchlorate. This is confirmed by IR spectra, where Vcn, vibrations are present at 3080 and 3070 cm-’ in contrast to sparteinium salts where the bands of these vibrations are further shifted to the interactions are additionally region of Vcn . Our observations on anion-cation confirmed bi the spectra of deuterated analogues of quaternary lupanine salts. In both salts the bands of vC_n vibrations of the sN+-CD, group are broad and blurred, but in the spectrum of methperchlorate a maximum can be distinguished at 2350 cm-’ whereas in the methiodide spectrum there are flattened doublets at 2300 and 2275 cm-‘. Similar, but even more blurred and broadened absorption bands from stretching vibrations of the N+-C!D3 group are visible in the IR spectra of ICD:. Cl04 (compare Fig. 1 of ref. 4 with Figs. 2 and 3). In these three cases the N+--CH3(N++D3) groups are located in boat conformers of ring C; hence they are directed tram relative to the N(1) atoms of ICH: and IICHS, and are easily accessible for various intermolecular and interionic interactions. We assume that the latter factors are responsible for the blurred absorption bands of N+-CD3 groups, the vibrations of which must be strongly perturbed in IICH; 1 X- (X- = I- and ClO,) and ICH;. ClO; salts. In contrast, as was l
204 TABLE 7 Intramolecular distances (in A) between N( 1) and N( 16) atoms in methiodides and methperchlorates of I and II (X-ray data from ref. 4 and this work) Distance between N( 1) and N( 16) atoms
Differences (A I, A ‘) in N(l)**. N( 16) distances (A)
Measured value
Average value
A’
ICH; * IICH; * CIO;
3.620 3.570
3.595
0.050
IICH; - IIICH; * CIO;
3.689 3.710
Compound
3.699
AZ
(d1--
4210,)
-
dICH;)
b
0.069
’ 0.140 i
0.021
(b)
(a)
&.p
(hCH;
‘i!$J~~ fyp+jp 3: q&, 0
Y
Fig. 5. The projection of crystal structure along the cx axis. (a) 2-Oxosparteine methiodide (IICHi*I-);symmetry code: (i) 1 -x, -l/2 + y, l-z; (ii) Jc, -l/2 + y, i; (iii) 5, -l/2 + y, 1 - z. (b) 2-Oxosparteine methperchlorate (IICH: ClO;); symmetry code: (i) 1 -x, -l/2+y,1~z;(ii)2~~~~l/2+y,1~~. l
noted in ref. 4, the N+--CHS(N+ZD3) group in IIICH:. I- vibrates in a normal, unperturbed manner giving rise to two bands from symmetric and asymmetric stretching vibrations, located at 3060 and 3015 cm-’ (in IIICD: Iat 2295 and 2260 cm-‘, respectively). Significant differences in the location and intensities of IR Vcn,(Vcn,) bond among isomeric quaternary cations. ICH: and IIICH; (ICD; and IIICD:) were explained by us in ref. 4 as being due to steric reasons namely, the inaccessibility of IIICH: and easy accessibility at ICH:, of the N+--CH3 groups to the formation of quasi hydrogen bonds with counter anions. To prove this hypothesis the IR spectra of IIICH: * ClO; and IIICD,‘. CIO, were compared with those of IIICH: * I- and IIICD;. I- (see Fig. 4). According to our prediction the shape and intensities are at first of VN+_cn and ~~+_~n bands in methiodide and methperchlorate glance thl same, indkating that the N+-CH, groups located inside the cationic molecule are inaccessible for I- as well as ClO, anions. l
205 TABLE 8 Interionic contacts (A) Parametera
Parametera
IICH;. I-’
IICH; . ClO;
Contacts between N( 1 )-_I’ N( 16)-I’ O-I’ N( 16)-I” C( 18)-I” .,. N( 16 )-I.‘,: C( 1 8)-F11
the cation and the centre of anions N( 1 )-Cl’ 4.755( 6) N( 16~Cl’ 5.001(6) O-Cl’ 4.222( 7) N( 16)-Cl”’ .. . 5.184(6) C( 1s )--Cl”’ 4.282( 9) N( 16~Cl” 4.657( 6) C( 18~Cl” 4.230( 9)
4.750( 5) 5.027( 5) 4.422(6) 5.317(5) 4.429(8) 4.834( 5) 4.395(8)
Contacts between 0-q 7)i” 0-C( 8)iv 0-C( 14)” 0-q 17)‘” 0-C( 18)‘”
cations <3.4 ..k. All C**.C contacts are >3.6 a 0-q 7 )i” 3.12(l) O-C( 8)iv 3.29( 1) 0-q 14): 3.32(l) 0-q 17)‘” 3.28( 1) O-C( 18)‘” 3.18(l)
3.186(7) 3.332(8) 3.370( 9) 3.334(8) 3.157(9)
Symmetry (i) (ii) (iii) (iv) (v)
1-x,-1/2+ y, l-2 x, -l/2 + y, z ;Y, -l/2 + y, 1 - 2 1 + x, Y, z 1 -x, l/2 + y, 1-z
1 -x, 2 -x, 2-q -1 + 1 -x,
code -l/2 + y, 1 - 2 -l/2 + y, l-2 -l/2 -I- y, 2-z x, y, z l/2 -t y, 1 -z
aSuperscript indicates symmetry code.
A closer examination of the set of four IR spectra in Fig. 4 shows us the following small but significant differences between methperchlorate and methiodide of III. (1) The IR region of the so called “truns” band [ 12-151 (2800-2600 cm-‘) in normal and deuterated preparations of the methiodide of III are identical which unequivocally indicates that deuteration does not affect the protons around N(1) atoms; hence two additional unexpected VC.-n bands at 2180 and 2090 cm-’ must also be connected with the vibration of N+-CD3 groups. If so, this is a very rare and new case in which the stretching vibration of one N+-CD3 group gives rise to four well separated bands (two doublets at 2295/2260 and 2180/2090 cm-‘). For this phenomenon we found only one reasonable explanation. The rotating N+-CH3 groups interact intramolecularly with the free electron pair of the N(1) atom by two different modes: (i) the orientation of three C(18)-H bonds relative to the three C-N( 16) bonds is staggered (form A in Scheme 2) but in consequence, the H atom from one C(lS)-D bond is much too close to the N(1) atom, so both atoms, before forming a relatively strong quasi hydrogen bond, have to repel each other which introduces some intrinsic strain into that form of cation;
206
(ii) the orientation of three C(18)-H bonds towards three N(16)-C bonds results in a thermodynamically unfavourable eclipsed form (B in Scheme 2) which, however, being without intrinsic strain is additionally stabilized by two weak quasi hydrogen bonds. We assume that both forms are either frozen in the crystal lattice or are in slow equilibration which is visible on the IR time-scale. If our explanation for the presence of two doublets of bands in the IR region of Vc-n is correct, and the predicted equilibrium between two rotamers (staggered A and eclipsed B in Scheme 2) is thermodynamically controlled, the enthalpy difference between rotamers A and B should have a small negative value since double bands at 2295/2260 cm-’ are significantly more intense than those at 2180/2090 cm-’ (see Fig. 4). (2) In the above IR region of the methperchlorate of III (see Fig. 4), there are also two pairs of bonds having shape, relative intensity and localization similar to those of the methiodide of III. Very small shifts of all four bands by 3-5 cm-’ to longer wavelengths seems to indicate that both types of hydrogen bonding are a little stronger in methperchlorate than in methiodide, probably because iodide anions, due to their different shape and proton acceptor activity, do not interact with IIICDf cations in the same manner as perchlorate anions. This can be seen even better in the “tram” band region of the IR spectra of methperchlorate and methiodide of III (Fig. 4). There are some significant differences, not only between methperchlorate and methiodide, but also between normal and deuterated preparations of methperchlorates, although in this case the differences are much smaller. Comparative observations of the shape and intensities of the “trans” band regions from the above two quaternary salts of III and of the free base of III and its 2-0~0 derivatives unequivocally indicate that iodide anions do not change it whereas perchlorate anions do. Similar conclusions were drawn from differences in the “trans” band region of ICH: * X(X- = I-, ClO:) [ 41 where the N+--CH3 groups are easily accessible for direct interaction with counteranions, but the explanations of both phenomena must be different. In the latter case it was reasonable to assume on the basis of X-ray data [4] that due to the direct dimeric mode of interaction of one perchlorate anion with geminal C-H bonds from N+--CH3 groups, the boat conformation of ring C was significantly deformed. In consequence, two axially oriented hydrogen atoms from C( 17) and C( 11) interact in an “anti Hamlow” [4] manner with antibonding orbitals of C(lO)-H and C(6)-H bond which are responsible for the shape and intensities of the “trans” bond. For steric reasons a similar explanation could not be adopted for both quaternary salts of III, and there being no X-ray data for the molecular and crystal structures of IIICH:. I- and IIICH:. ClO; we can now present only a tentative explanation as to why perchlorate does and iodide anions do not change the “tram” band in IIICH; cations. In the case of IIICH; cations the quaternary N+--CH3
201
Scheme
2
groups are cisoidal to the basic N(1) atoms, interacting with that accepting center by hydrogen bonding modes. As has already been mentioned, from the localization of two pairs of C-D bands we assume that type of intramolecular hydrogen bond to be stronger in the case of IIICH:. ClO;, and in consequence, stronger participation of the free electron pair of the N(1) atom in methperchlorate is responsible for significant changes in the shape and intensity of its “truns” bands. We could, however, accept another explanation; namely directed interaction of perchlorate anions with C-H bonds which are responsible for the “trans” band (and their antibonding orbitals) in the anti “Hamlow” style. Most probably both factors discussed above diminish the shape and intensity of the “truns” band in methperchlorate of III. We hope that our studies now in progress on the nature of the “truns ” band will also answer these questions. We also hope that the hypothetical explanation for the presence of two pairs of ~c_n bonds in the IR spectra of IIICH: * X- presented in this paper will be
208
unequivocally nary N-methyl
solved by our further study on the stereochemistry cations of quinolizidine derivatives.
of quater-
ACKNOWLEDGMENTS
We thank Dr. T. Lis of Wroclaw University for rendering the computer accessible to us and for his help in calculating the structure of 2-oxosparteine methperchlorate. REFERENCES 1 R. Mosquera, L. Castedo and I. Ribas, Ann. Quim., 70 (1974) 609. 2 L. Castedo, I. Ribas and R. Riquera, Acta Cient. Compostelana, 11(l) (1974) 23. 3 K. Langowska, J. Skolik and M. Wiewiorowski, Bull. Acad. Pal. Sci., Ser. Sci. Chim., 25 (1977) 11. 4U. Majchrzak-Kuczynska, A. E. Koziol, K. Langowska and M. Wiewiorowski, Bull. Acad. Pol. Sci., Ser. Sci. Chim., 32 (1984) 233-253. 5 H. Maluszyiiska, A. Hoser and Z. KaIuski, Acta Crystallogr., Sect. B, 35 (1979) 910. 6 M. S. Lehman, F. K. Larsen, Acta Crystallogr., Sect. A, 30 (1974) 580. 7 M. Jaskolski, Ph.D. Thesis, Adam Mickiewicz University, Poznan, 1979. 8 Syntex XTL, Operation Manual, Cupertino: Syntex Analytical Instruments, 1973. 9 International Tables for X-Ray Crystallography, Vol. IV, The Kynoch Press, Birmingham, 1974. 10 S. C. Nyburg, Acta Crystallogr., Sect. B, 30 (1974) 251. 11 W. L. Duax and D. A. Norton, Atlas of Steroid Structure, Vol. 1, Plenum, New York, 1975. 12 J. Skolik, P. J. Krueger and M. Wiewiorowski, Tetrahedron, 24 (1968) 5439. 13 H. P. Hamlow and S. Okuda, Tetrahedron Lett., (1964) 2553. 14 L. J. Bellamy and D. W. Mayo, J. Phys. Chem., 80 (1976) 80. 15M. D. Bratek-Wiewiorowska, U. Rychlewska and M. Wiewiorowski, J. Chem. Sot., Perkin Trans. 2, (1979) 1469.
THE STEREOCHEMISTRY OF QUATERNARY N-METHYL SPARTEINIUM CATIONS, THEIR DERIVATIVES, STEREOISOMERS AND ANALOGUES Part II. Molecular and crystal structure, and IR spectra of methiodide and methperchlorate of Z-oxosparteine
U. MAJCHRZAK-KUCZYNSKA Institute of Organic Chemistry, Academy
of Economics,
PoznaA (Poland)
A. E. KOZIOL Institute of Chemistry, M. Sklodowska-Curie
University, Lublin (Poland)
M. WIEWICROWSKI Institute of Biooqanic (Received
Chemistry, Polish Academy
of Sciences, Poznah (Poland)
1 October 1986)
ABSTRACT The crystal and molecular structures of two quaternary salts of 2-oxosparteine (II), the methiodide (IICH:* I-) and the methperchlorate (IICHz* ClO;) have been determined on the basis of X-ray and IR data. The studies were performed by analogy to previously investigated quaternary salts of sparteine (I), the methiodide (ICHin I-) and the methperchlorate (ICH;. ClO;). As expected, the configurations and conformations of cationic parts within the two pairs of quaternary salts are identical, except for the structure of their A/B fragments, which in ICH: cations have the character of tertiary amines, but in IICH: that of la&ems. On the basis of accumulated X-ray and IR data the similarities and differences in the modes of interaction of perchlorate and iodide anions with quaternary cations, and especially with their N*-CH, groups are discussed. In this discussion are also included the methiodide and methperchlorate of ol-isosparteine: IIICH:. X- (X- = I- or ClO;) where N+-CH, groups are cisoidally oriented to the basic nitrogen atoms. The most interesting observations are as follows: (i) When N+-CH, groups are easily accessible for direct quasi hydrogen bonding interactions with counter anions and when other positive charged groups, for instance lactam groups, are absent in quaternary cations, perchlorate anions interact more” strongly than the iodide anions and in consequence introduce conformational changes into the ring with N+-CH, group as well as into further rings. (ii) Perchlorate and iodide anions interact with N+-CH, groups similarly and very weakly if at all, when the N+--CH, groups are for steric reasons inaccessible to counter anions or when in quaternary cations there are additional groups which attract the counter anions electrostatically. The last mechanism operates in both quaternary salts of 2-oxosparteine and this is the reason why their monocrystals are isosteric and IR spectra almost identical. (iii) The sterically hindered N’-CD, groups in both IIICDi* X- salts give rise in their IR spectra to two doublets of sharp, well resolved bands which indicate the presence of two different rotamers stabilized by two modes of weak intramolecular hydrogen bonds with 0022-2860/87/$03.50
0 1987 Elsevier Science Publishers B.V.
190
basic N atoms. (iv) In IIICH:* X- and IIICD:. X- salts the perchlorate and iodide anions do not interact at all with the rotating and vibrating N+-CH, (N+-CD,) group but the structures of these salts are not isosteric since the perchlorate anions interact more strongly than iodide anions with the A/B fragment of the IIICH: cations. This is visible from the shapes and intensities of the so-called “tram” band in the IR spectra of both salts. INTRODUCTION
Rejection of the incorrect structures of sparteine-iV( 16)-methiodide and sparteine-l\r( 16)-methperchlorate (ICH,‘* I-, ICH:* CIO;) [l-3] and the determination of the correct ones, logically resulted in a revision of erroneous interpretations of the vibrational spectra of these compounds [4]. Next, a new determination of the structure and spectroscopic properties of 2-0x0sparteine-iV( 16)-methiodide and 2-oxosparteine-N( 16)-methperchlorate (IICH:* I:, IICH:* ClO,) was undertaken; this issue is the subject of the present paper. Although an easy and efficient transformation of 2-oxosparteine (II) into sparteine (I) and IICH$- ClO, into ICHl* ClO; could be sufficient proof of analogous molecular conformations of both quaternary salts of I and II (Scheme l), we wanted to exclude completely the possibility of isomerization in the course of the reduction of IICH,‘- X- to ICH,‘. X- (X = I- or ClO;). For this reason single crystals of IICH:* I- and IICHf- ClO, were subjected to X-ray analysis. As in the case of two quaternary salts of I [4], simultaneous studies on molecular and crystal structures of IICHS- ClO, and IICH;* I- were aimed at tracing the influence of perchlorate and iodide anions on the fine differences in the deformations of the four coupled heterocyclic rings. In ICHg* X- four piperidine rings were found, forming two tram quinolizidine systems: A/B, double chair with tertiary nitrogen atom; and C/D, boat-chair with quaternary nitrogen atom. On the other hand, in quaternary salts of the type IICH:* Xthe A/B rings form a truns quinolizidone system probably within a sofa-chair conformation as in IIHClO,,* Hz0 [ 51. In short, the present paper should answer two questions: (1) whether the configuration and conformation of the C/D fragments of ICH:- X- and IICH:. X- are analogous, and (2) whether the structural and chemical differences between the A/B fragments of these cations (a basic double chair tram quinolizidine system with tertiary nitrogen atom in the case of I; a neutral sofa-chair tram quinolizidine system with a lactam group in the case of II) significantly influence the complex interactions between methquinolizidine quaternary cations and the ClO; and I- counter anions.
191
CH,I I
ICi-lfX
x=i;cl& scheme
1
EXPERIMENTAL
Materials 2-Oxosparteine methiodide (IICHd* I-) 6.2 g 2-oxosparteine (II) were dissolved
in 50 ml methyl iodide, and the solution stored in darkness at room temperature. After a few minutes, the first crystals began to appear in the colourless solution. The reaction was over within four days, and proceeded with nearly 100% efficiency. The well grained crystals which were obtained (first crop, 7.71 g; second crop, 0.92 g) were recrystallized in methanol. M.p. = 281-285°C (decomp.); [LX]ho = +54.0 (HzO, c = 1). Elemental analysis was in agreement with the formula C16H27NZOI.
192
Deuterated analogue of 2-oxosparteine methiodide (IED; * I-) 0.26 g 2-oxosparteine (II) was dissolved in 5 ml acetone and 0.63 ml CDJ
was added. The reaction was completed after three days. 0.36 g colourless crystals was obtained. Elemental analysis was in agreement with the formula C~~H~QD~N~CI. 2-Oxosparteine methperchlorate (IED: * CZO4)
(IICH:
* (30,)
and its deuterated
analogue
These compounds were obtained by the exchange of the iodide anion in IICH,‘. I- and IICD;* I- for a perchlorate anion using a Dowex column. Normal and deuterated methperchlorates of ac-isosparteine (III) were obtained similarly (IIICH: - ClO, and IIICD: 0 CIO;). IR analysis
IR spectra were measured on a Perkin-Elmer 180 spectrophotometer the suspension technique in Fluorolube and Nujol. X-Ray structure
using
determination
The crystals were obtained by recrystallization from methanol solutions. Crystal data for both salts are summarized in Table 1. Intensities of Bragg reflections were collected on a Syntex P2, four-circle diffractometer using graphite monochromatized MO Kol radiation. No background measurements were made; the Lehmann and Larsen [6, 71 method was applied to calculate the intensity of each reflection from a peak profile. Intensities were corrected for Lorentz and polarization effects. Both structures were determined in a similar way: first, Patterson synthesis was calculated for determination of I or Cl atom position, and then subsequent Fourier maps gave C, 0 and N atoms. Experimental details and results of the refinement are shown in Table 2. TABLE 1 Crystal data IICH; . IFormula Crystal system Space group Unit cell parameters a (A) b (A) c (A) P (deg.) v (A3) z D, (g cm-%)
lG&N,Ol+I-
IICH; . ClO;
t%H,,N,Ol+C10;
monoclinic p2,
monoclinic p2,
7:780(2) 15.398( 2) 7.377( 2) 108.69(2) 837.1(2) 2 1.55
7.882( 2) 15.682( 2) 7.456( 1) 107.80( 1) 877.4( 3) 2 1.37
193
Calculations were performed on a NOVA 1200 minicomputer with a Syntex XTL system [8]. The atomic scattering factors were taken from the International Tables for X-Ray Crystallography [9]. RESULTS
Final coordinates and isotropic temperature factors are given in Tables 3 and 4. Bond lengths and angles as well as torsion angles for cations of both salts are collected in Table 5. The conformation of the methyl 2-oxosparteine cation is illustrated in Fig. 1.
Fig. 1. The conformation cation (IICH:).
and atom numbering scheme of N-methyl-2-oxosparteinium
TABLE 2 Experimental conditions and results of least squares refinement
Crystal dimensions (mm) ~(Mo Kol)(mm-l) 20 Range (deg.) Scan mode Scan width (deg. min’) Range of transmission factors for absorption corrections hkl Range Number of reflections measured used in the final refinement (I > 1.960(Z)) Number of refined parameters R = ~(AF(/zF, R, = [x w(A F)Z/cw(F,)Z]"Z w ifF, < 4.5 if 4.5 < F, =Z53 if F, > 53 Goodness of fit c [w(F, - F,)* l”2/(N, - N,) H atoms
IICH; . I-
IICH; * CIO;
0.35 x 0.4 x 0.5 1.94 O-48 e/2e 2.0-29.3 0.66-1.00
0.5 x 0.45 x 0.55 0.25 O-52 .9/2&J 2.0-29.3 Not applied
0.08-8,
009~-8,19,9
17, 8
1361 1269
1497 1362
180 0.039 0.040 (F0l4.5)’
216 0.063 0.059 l/o’(F)
(153/F,). 3.52
4.98
19 found in D map; 8 with positions calculated
27 in positions calculated from geometry of cation
194 TABLE3 Non-hydrogenatom coordinates (X 104;x lo5 forI atom)and& Y
x
IICH;.II N(1) C(2) 0 C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(l0) C(l1) C(12) C(13) C(14) C(15) N(16) C(17) C(18) IICH;.ClO; Cl O(1) O(2) O(3) O(4) N(1) C(2) 0 C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(l0) C(l1) C(12) C(13) C(14) C(15) N(16) C(l7) C(18)
= 1/3XBi,(A') Bw
z
5076(7) 6910(g) 7840(g) 7765(11) 6651(11) 4725(11) 3872(g) 1969(g) 1257(9) 2441(12) 4317(9) 2663(10) 2504(12) 2953(12) 1815(4) 2006(10) 1452(8) 1861(10) -564(10)
25000(O) 272(4) 157(5) 20(5) 208(7) 673(6) 343(6) 538(5) 145(5) 410(5) -68(7) 360(5) -1043(5) -1597(6) -2512(11) -2892(6) -2315(6) -1380(4) -845(6) -1393(6)
12137(9) 6838(8) 7604(11) 6577(10) 9735(12) 10795(11) 10047(11) 7935(10) 7068(10) 4984(11) 3999(12) 4750(10) 4394(11) 2666(12) 3181(12) 4399(14) 6094(11) 5525(9) 7342(11) 4408(12)
5.64(6) 2.1(4) 2.3(5) 3.6(5) 3.6(7) 3.3(6) 3.1(6) 2.3(5) 2.4(6) 2.4(5) 2.2(6) 2.3(5) 2.4(5) 3.3(6) 5.0(8) 4.2(8) 3.4(8) 2.3(5) 2.7(6) 3.1(6)
7697(3) 9072(12) 6691(14) 6683(19) 8362(20)
7500(O) 8049(6) 7355(11) 7781(10) 6748(8)
8903(3) 9074(12) 7191(14) 9914(20) 9543(25)
4.8(2) 13.0(12) 18.7(19) 24.6(21) 21.3(22)
5236(4) 5173(4) 5079(4) 5221(5) 5643(5) 5291(5) 5505(4) 5134(5) 5407(4) 4933(4) 5314(4) 3968(4) 3419(5) 2472(6) 2161(5) 2712(4) 3655(3) 4177(4) 3688(5)
3095(6) 2354(8) 3372(7) 236(10) -819(g) -122(9) 1973(8) 2830(g) 4885(g) 5900(8) 5162(8) 5469(8) 7236(g) 6751(10) 5558(11) 3840(g) 4398(6) 2564(8) 5447(10)
2.5(3) 2.8(5) 4.2(4) 4.0(6) 3.9(6) 3.8(6) 2.7(5) 2.9(5) 3.1(5) 2.7(5) 3.0(5) 2.8(5) 3.7(6) 5.0(6) 4.4(6) 3.7(6) 2.4(3) 3.2(5) 3.6(6)
22829(g)
4736(6) 2941(8) 1987(6) 2081(g) 3248(10) 5090(10) 5927(8) 7819(8) 8478(g) 7338(8) 5464(8) 7168(8) 7393(9) 7046(10) 8141(11) 7929(9) 8412(6) 7993(9) 10374(8)
195 TABLE
4
Hydrogen
atom
coordinates IICH;
Atom
x H(31)a H(32)a H(41) H(42) H(51)a H( 52)a H(61)a H(71)a H(81)a H(82)” H(91)a H(lOl)a H( 102) H(lll)a H(121)a H( 122)a H(131)” H( 132) H(141)a H( 142)a
779 922 667 715 421 470 346 139 134 1 193 504 426 384 346 115 433 268 25 206
H(151)” H(152)a H(171) H(172) H(181) H( 182)a H(183)
130 313 306 89 -98 -65 -133
aAtom
position
(X
103) Biso = 5.0 AZ for all hydrogen-atoms
- I-
Atom Y -43 49 131 56 65 -34 115 34 114 32 2 8 100 -115 -135 -173 -249 -292 -300 -354 -250 -240 -105 -97 -79 -191 -154
z
IICH; . ClO; X
1013 1018 1055 1219 1083 1037 769 781 501 446 253 412 449 500 192 154 393 201 330 520 703 700 823 793 375 328 525
H(31) H(32) H(41) H(42) H(51) H(52) H(6) H(7) H(81) H(82) H(9) H( 101) H(102) H(l1) H(121) H(122) H(131) H( 132) H( 141) H( 142) H( 151) H( 152) H( 171) H( 172) H(181) H( 182) H( 183)
180 95 271 326 506 584 605 860 978 836 791 466 551 618 865 655 736 577 947 782 874 668 685 897 1050 1100 1100
Y 463 555 551 627 465 555 613 537 525 604 499 500 593 402 349 362 213 239 216 156 249 267 396 408 350 325 425
2 -24 -2 -220 -63 -30 -86 205 214 544 498 728 575 552 427 811 790 795 605 632 512 313 304 170 201 650 550 550
from D map.
Structure factor lists and anisotropic thermal parameters for non-H atoms are deposited with the British Library Lending Division as Supplementary Publication No. 26331 (15 pp.). IR spectra in the range 3200-1500 cm-’ and 1500-400 cm-’ for eight salts: IICH;. X-; IICD; * X-; IIICH: X-; IIICD: * X- (X- = I-, CIO,) are presented in Figs. 2, 3 and 4. l
DISCUSSION
The X-ray analysis of IICH: - I- and IICH; - ClO, performed in the course of our studies unequivocally proved the tram configuration of the quinolizidine C/D fragment of both compounds, as had been previously determined [4] for cations of sparteine quaternary salts (ICH;. X-). In the IICH: cation
196 TABLE5 Molecular geometry Parameter Bond length(A) N(lW(2) N(l)-C(6) N(l)-C(lO) C(2)--0 C(2w3) C(3)+(4) C(4)+(5) C(5W(6) C(6)--c(7) C(7)--C(l7) C(7)-+(8) C(8)--C(9) C(9)--C(lO) C(9)-C(ll) c(11)-c(12) C(ll)--N(16) C(l2wl3) C(13)-C(14) C(14)-C(15) C(15)--N(16) N(16)--C(17) N(16)-C(18)
IICH;*I-
1.367(10) 1.478(9) 1.469(9) 1.222(10) 1.500(11) 1.520(13) 1.510(3) 1.514(11) 1.536(11) 1.543(12) 1.514(11) 1.532(12) 1.534(12) 1.529(13) 1.506(11) 1.535(10) 1.472(9) 1.563(15) 1.502(13) 1.523(11) 1.518(10) 1.520(10)
IICH;*ClO;
1.356(8) 1.497(8) 1.476(8) 1.230(8) 1.518(10) 1.531(10) 1.491(10) 1.535(10) 1.545(8) 1.527(10) 1.521(10) 1.531(9) 1.532(9) 1.544(9) 1.539(10) 1.523(8) 1.532(12) 1.498(11) 1.511(11) 1.552(8) 1.540(8) 1.506(8) 1.36(1 1.30(1 1.33(2 1.32(1
Cl-o(l) Cl-O(2) Cl-O(3) Cl-O(4) Bond angles (deg.) C(2k---N(1)-c(6)
C(2)-N(l)-C(lO) C(G)-N(l)-C(lO) N(l)--C(2)--C(3) N(1)-%(2)-0 0-C(2)-C(3) C(2)--C(3W(4) C(3)-C(4)--C(5) C(4)-C(5)-+(6) C(5)--c(6)--c(7) C(5)--c(6)-N(1) C(7)-C(6)-N(1) C(6)-C(7)--C(17) C(6)--C(7)-C(8) C(17)-C(7)-C(8) C(7)-C(8)-C(9) C(8)-C(9)--C(lO) C(8)--C(9)--c(ll)
124.7(6) 117.4(6) 115.9(6) 118.7(7) 120.8(7) 120.5(7) 115.4(7) 108.4(7) 111.5(7) 113.3(6) 111.3(6) 111.0(6) 114.8(6) 107.8(6) 112.4(6) 105.8(6) 105.6(7) 115.4(7)
123.2(4) 117.1(5) 116.8(4) 119.9(5) 121.0(5) 119.0(5) 114.1(5) 109.6(6) 110.1(5) 113.5(5) 111.1(5) 110.7(4) 115.5(5) 107.4(5) 113.0(5) 106.9(5) 106.3(5) 113.6(5)
197 TABLE
5 (continued) IICH;
c(10)-C(9)-+(11) C(9)-C(lO)-N(1)
108.5(7) 110.8(6) 114.9(7) 112.6(6) 111.7(6) 112.0(8) 112.1(9) 109.5(8) 112.7(7) 106.8( 6) 111.9(6) 114.6(6) 107.5(6) 107.7(6) 108.0(6) 115.2(6)
107.1(5) 111.5(5) 113.0(5) 113.4(5) 110.1(5) 112.0(6) 111.2(6) 112.5(6) 111.3(5) 107.5(5) 110.5(5) 116.1(4) 107.7(4) 107.3(4) 107.4(5) 114.2(5)
-19.9( 10) 46.5( 10) -61.8( 10) 49.0(8) -21.5(9) 7.0( 10)
-20.3(7) 46.1(7) -62.7(7) 52.3(6) -26.7(6) 11.1(7)
N(l)--C(6)+x7)--C(8) C(6)+?7)+J8)--c(9) C(7)-c(8)-c(9)-c(lO) C(8)+(9)+YlOk--N(1) C(9)-C(lO)-N(l)-C(6) C(lO)-N(l)-C(6)+(7)
-55.6(9) 68.0(S) -69.8( 8) 60.1(9) -50.5(8) 47.6(8)
-55.0(6) 68.3(6) -69.1(6) 57.5(6) -47.9(6) 46.1(6)
Ring C C(7)-C(17)-N(16)-C(ll) C(17)-N(16)--C(ll)-C(9) N(16)-C(ll)-C(9)-C(8) C(ll)-C(9)-C(8)-C(7) C(9)-+?(8)-C(7)-C( C(8)-C(7)-C(17)-N(16)
45.6(7) -55.1(8) 7.0(8) 50.1(8) -59.6( 9) 12.1(6)
46.0(6) -57.4(5) 9.8(6) 48.4(6) -60.2(6) 12.3(5)
56.6( 10) --53.1(12) 53.8(12) -57.2( 9) 57.7(8) -58.9(9)
56.9( 7) -52.3(7) 52.6(8) -57.4(7) 59.5(6) -58.9(9)
C(9)--c(ll)-C(l2) C(9)-C(ll)-N(16) C(12)-C(ll)-N(16) C(ll)-C(12)-C(13) C(12)--C(13)-C(14) C( 13)--q 14)--q C( 14)-C( 15)-N( C(lS)-N(16)+(15) C(18)-N(16)-C(17) C(18)--N(16)--C(ll) C(ll)-N(16)<(15) C(ll)-N(16)+(17) C(17)-N(16)+(15) C(7)-C(17)-N(16) Torsion
angles
15) 16)
* I-
IICH; . ClO;
Parameter
(deg.)
Ring A N(1)--C(2)_-C(3)--C(4) C( 2)-C( 3)-C(4)-C(
5)
C(3)-C(4)~(5)-C(6) C(4)-C(5)-C(6)-N(1) C(5)-+(6)-N(l)-+(2) C(6)-N(l)--C(2)-+?3) Ring B
17)
Ring D N(16)-C(15)-C(14)-C(13) C(15~C(14)-C(13)--C(12) C(14)--C(13)-C(12)-C(11) C(13~C(12)--C(ll)-N(16) C(12)--C(ll)-N(16)-C(15) C( ll)-N( 16)-C( 15)X(
14)
198 TABLE
5 (continued) IICH;
* I-
IICH; . ClO;
External 0-C( 2)-N( 1)-C(6) O-C(2)-C(3)-C(4) O-C(2)-N(l)-C(lO) C(18)--N(16)--C(15)-C(14) C(18)-N(16)-C(ll)-C(12) C( 18)-N( 16)-C( ll)-C( C(18)--N(16)-C(17)--C(7)
-172.8(11)
-168.7(7) 159.5(7) --8.7(7) 66.1(6) -61.1(6) 66.6( 6) -81.5(5)
159.9(10) -9.4( 11) 64.5(7) -60.9( 8) 9)
70.2(7) -81.3(7)
particular rings occur in the following conformations: ring A, deformed halfchair; ring B, chair; ring C, deformed boat; ring D, chair (Fig. 1). Comparison of the geometries of the cationic fragments of both salts (IICH:. X-) made using the BMFIT programme [lo], shows them to be almost identical (the sum of standard deviations squared between atom pairs equals Zu2 = 0.856 a”). A detailed conformational analysis using asymmetry parameters [ll] is presented in Table 6. Comparing the values of these parameters for the C rings, in which the methylammonium groups are located in ICH: and IICHS cations, it can be seen that a boat conformation significantly and similarly deformed is present in the three following cations: IICHS * I-, IICH,‘. ClO, and ICH: - ClO,. In turn, ring C possesses well preserved boat conformation symmetry elements in the cation of I,,SCH:. I- [4]. The very similar and strongly deformed boat conformation of ring C within both quaternary salts of 2-oxosparteine (IICHS * X-) seems to indicate that in these cases counter anions have no influence on the degree of deformation of the C-ring conformation since pronounced repulsion forces act between N6’(1) and N’(16) atoms which are respectively partly or fully positively charged. Comparison of the distances between N(1) and N(16) in the four quaternary salts considered (ICH; * X- and IICH: X-) fully verify the above statements (see Table 7). In both quaternary salts of compound II this distance is longer by 0.1 a than that in analogous salts of I, where the nitrogen atoms at the A/B ring are basic and not lactamic in character, and in consequence attract instead of repel the positively charged methylammonium N( 16) atoms. The crystals of both IICH: - I- and IICH: - ClO; are isostructural, as illustrated in Fig. 5. Upon comparison of the packing of the ions in crystals, one can state that the I- and ClO, anions “substitute” each other. The distances between the centre of the anion (I, Cl; symmetry code (i) in Fig. 5) and atoms N( 1) and N( 16) of the car-ion are compatible in both structures (Fig. 5). However, the environment of the 3N+--CH3 group is somewhat different. Weak electrostatic interactions of the sN+--CH3 group with two I- anions are observed in methiodide, whereas in methperchlorate only the weaker van der Waals type of interactions between the ClO, anion and cation are present. l
199
Probably the above small differences within weak interactions of I- and ClO; anions with the same IICH; cations are expressed by a shortening by 0.021 A of the N(l)*** N( 16) distance in IICH:* I-, in comparison with that present in IICH3 - ClO; (see Table 7). As stated above, the average N( 1). * - N( 16) distances within both sparteine quaternary salts (ICH:* X-) are significantly shorter (by 0.1 A) than in analogous quaternary salts of II, since in the ICH: cation a weak electrostatic attraction exists between basic N(1) and positively charged N(16). In consequence, the boat conformation of ring C in ICH: - I’ is almost ideal since very polarizable iodide anions form a set of hydrogen bonds around quaternary N(16) atoms which stabilize that conformation. In the case of ICH:* ClO,, the perchlorate anion forms two geminal hydrogen bonds with the N+(16)CH3 group which significantly deform the boat conformation of ring C and in consequence the stretching vibrations of C(lO-H and C(6)-H bonds (see Fig. 5 of ref. 4). The question still remains as to why the proton acceptor activity of ClO; anions towards IICHS cations is so weak that it can be neglected, whereas towards the ICH; cations it is significant and deforms the boat conformation of ring C. Assuming that repulsive forces operating between N(1) and N(16) in IICH: cations are responsible for a pronounced deformation of the boat conformation of ring C, but not for decreasing the proton donor activities of the N’(16)-C-H bonds, there seems to exist only one reasonable explanation; that the dipole of the lactam group in IICH: electrostatically attracts the Cl04 anions more strongly than I- anions. Such an assumption is fully justified, since the dimensions and geometry of the ClO, anion could enable it to approach more easily than I- anion the positive end of the lactam group located inside the IICHS cation. In consequence the concentration of ClO; anions around the quaternary N(16) atoms of IICH: is significantly diminished, causing an increase in the distance between cation and anion (see Table 8). In summary, we can say that different dimensions, geometries and polarizabilities of ClO, and I- anions are responsible for differences in hydrogen bonding and electrostatic interactions between cationic and anionic fragments within the pairs of quaternary salts ICH: * I--1CHS - ClO, and IICH: * I’ IICHS * CIO,. In the first pair both anions form relatively strong hydrogen bonds but different organizations with the quaternary N+(lG)-CH3 groups, whereas in the second pair these anions interact very weakly and similarly with the N’( 16)~-C!H3 cationic fragments, since they are additionally involved in different weak electrostatic interactions with lactam groups. The consequence of this distribution of weak electrostatic interactions of I- and (30, on two positively charged centers of the IICHS cation (located at the quaternary N( 16) atom and lactam group atoms C( 2) and especially N( 1)) is that the crystals of IICHf * X- (X- = I- or (30,) are isostructural. X-ray structural conclusions are in very good agreement with spectroscopic
200
I I
3000
2000
2500
1KJO
1800
cm-’
Fig. 2. IR spectraof 1500
cm-’
IICH;.
(Fluorolube).
I-, IICD:.
I-; IICD:.
ClO;
and IICDi-
ClO;
in the range 3200
201
:
* ‘,
1400
lZcfl
,:
800
loo0
&lo
400
cm-’
Fig. 3. IR spectra of IICH,+* I-, IICD,+* I-, IICD, +. ClO; 1400 cm-’ (Nujol).
and IICD:.
CTO; in the range 1500-
I 3000
2500
2ooo
Fig. 4. IR spectra of IIICHlI-, 3200-1500 cm-’ (Fluorolube).
IIICD:I-,
1800
1600cm"
1IICH:ClO;
IL00
and
IIICH;CD,ClO;
data (Figs. 2 and 3). The IR spectra of normal and crystalline preparations within the pair IICHf- I- and tical in very many points indicating that the structures identical. Some differences can be observed in those bonds of vcFo (from ClO;) occur. Differences in
in the range
selectively deuterated IICHl* ClO, are idenof the cations are also fragments where the the region of Vo-_H
203 TABLE
6
Asymmetry
parameters IICH;
- I-
IICH;
2.1 38.6 41.9 17.8
6.3 38.6 41.8 13.8
19.9
21.7
AC;
3.3
1.8
Ac;,~
6.6
9.1
15.7 13.4 12.4
12.1 12.8 14.5
AC5 A@ AC;
AC& AC;,' AC;
- I-
IICH;
- ClO;
AC;
8.3
15.9
Ac9’” s
10.5
11.9
AC;
31.6
29.6
AC;,'
38.3
36.2
AC’%‘3
3.0
4.0
AC)
3.6
5.0
AC”,‘2
4.9
7.2
0.9 2.3 3.6
0.3 3.4 5.3
Ring D
Ring B AC;*'
IICH;
Ring C
Ring A AC;.'
- ClO;
AC)
AC’%‘4 A$
2300-2100 cm-‘, are (fN+-CH3) 3080-2970 cm-’ and vc_,, (fN+-D3) very much smaller than those in spectra of ICH:* I- and ICHS* ClO, [4]. X-ray analysis indicates that such a situation is due to a markedly weaker interaction of the anions with the acidic hydrogen atoms of the >N+-CH3 groups in IICH:. X- than in analogous salts of I (distances I-(Cl-). lCH,-N’(16) for ICH,‘. I-, ICH:. ClO,, IICH,‘. I- and IICH:. ClO; are 4.04(l); 3.99(l); 4.230(g); 4.395(8) a respectively (see Tables 5 and 7 in ref. 4). As has already been stated, cationanion electrostatic contacts in quaternary IICH: * I- and IICH: * CIO; salts are weak, although in methiodide the contacts are closer than in methperchlorate. This is confirmed by IR spectra, where Vcn, vibrations are present at 3080 and 3070 cm-’ in contrast to sparteinium salts where the bands of these vibrations are further shifted to the interactions are additionally region of Vcn . Our observations on anion-cation confirmed bi the spectra of deuterated analogues of quaternary lupanine salts. In both salts the bands of vC_n vibrations of the sN+-CD, group are broad and blurred, but in the spectrum of methperchlorate a maximum can be distinguished at 2350 cm-’ whereas in the methiodide spectrum there are flattened doublets at 2300 and 2275 cm-‘. Similar, but even more blurred and broadened absorption bands from stretching vibrations of the N+-C!D3 group are visible in the IR spectra of ICD:. Cl04 (compare Fig. 1 of ref. 4 with Figs. 2 and 3). In these three cases the N+--CH3(N++D3) groups are located in boat conformers of ring C; hence they are directed tram relative to the N(1) atoms of ICH: and IICHS, and are easily accessible for various intermolecular and interionic interactions. We assume that the latter factors are responsible for the blurred absorption bands of N+-CD3 groups, the vibrations of which must be strongly perturbed in IICH; 1 X- (X- = I- and ClO,) and ICH;. ClO; salts. In contrast, as was l
204 TABLE 7 Intramolecular distances (in A) between N( 1) and N( 16) atoms in methiodides and methperchlorates of I and II (X-ray data from ref. 4 and this work) Distance between N( 1) and N( 16) atoms
Differences (A I, A ‘) in N(l)**. N( 16) distances (A)
Measured value
Average value
A’
ICH; * IICH; * CIO;
3.620 3.570
3.595
0.050
IICH; - IIICH; * CIO;
3.689 3.710
Compound
3.699
AZ
(d1--
4210,)
-
dICH;)
b
0.069
’ 0.140 i
0.021
(b)
(a)
&.p
(hCH;
‘i!$J~~ fyp+jp 3: q&, 0
Y
Fig. 5. The projection of crystal structure along the cx axis. (a) 2-Oxosparteine methiodide (IICHi*I-);symmetry code: (i) 1 -x, -l/2 + y, l-z; (ii) Jc, -l/2 + y, i; (iii) 5, -l/2 + y, 1 - z. (b) 2-Oxosparteine methperchlorate (IICH: ClO;); symmetry code: (i) 1 -x, -l/2+y,1~z;(ii)2~~~~l/2+y,1~~. l
noted in ref. 4, the N+--CHS(N+ZD3) group in IIICH:. I- vibrates in a normal, unperturbed manner giving rise to two bands from symmetric and asymmetric stretching vibrations, located at 3060 and 3015 cm-’ (in IIICD: Iat 2295 and 2260 cm-‘, respectively). Significant differences in the location and intensities of IR Vcn,(Vcn,) bond among isomeric quaternary cations. ICH: and IIICH; (ICD; and IIICD:) were explained by us in ref. 4 as being due to steric reasons namely, the inaccessibility of IIICH: and easy accessibility at ICH:, of the N+--CH3 groups to the formation of quasi hydrogen bonds with counter anions. To prove this hypothesis the IR spectra of IIICH: * ClO; and IIICD,‘. CIO, were compared with those of IIICH: * I- and IIICD;. I- (see Fig. 4). According to our prediction the shape and intensities are at first of VN+_cn and ~~+_~n bands in methiodide and methperchlorate glance thl same, indkating that the N+-CH, groups located inside the cationic molecule are inaccessible for I- as well as ClO, anions. l
205 TABLE 8 Interionic contacts (A) Parametera
Parametera
IICH;. I-’
IICH; . ClO;
Contacts between N( 1 )-_I’ N( 16)-I’ O-I’ N( 16)-I” C( 18)-I” .,. N( 16 )-I.‘,: C( 1 8)-F11
the cation and the centre of anions N( 1 )-Cl’ 4.755( 6) N( 16~Cl’ 5.001(6) O-Cl’ 4.222( 7) N( 16)-Cl”’ .. . 5.184(6) C( 1s )--Cl”’ 4.282( 9) N( 16~Cl” 4.657( 6) C( 18~Cl” 4.230( 9)
4.750( 5) 5.027( 5) 4.422(6) 5.317(5) 4.429(8) 4.834( 5) 4.395(8)
Contacts between 0-q 7)i” 0-C( 8)iv 0-C( 14)” 0-q 17)‘” 0-C( 18)‘”
cations <3.4 ..k. All C**.C contacts are >3.6 a 0-q 7 )i” 3.12(l) O-C( 8)iv 3.29( 1) 0-q 14): 3.32(l) 0-q 17)‘” 3.28( 1) O-C( 18)‘” 3.18(l)
3.186(7) 3.332(8) 3.370( 9) 3.334(8) 3.157(9)
Symmetry (i) (ii) (iii) (iv) (v)
1-x,-1/2+ y, l-2 x, -l/2 + y, z ;Y, -l/2 + y, 1 - 2 1 + x, Y, z 1 -x, l/2 + y, 1-z
1 -x, 2 -x, 2-q -1 + 1 -x,
code -l/2 + y, 1 - 2 -l/2 + y, l-2 -l/2 -I- y, 2-z x, y, z l/2 -t y, 1 -z
aSuperscript indicates symmetry code.
A closer examination of the set of four IR spectra in Fig. 4 shows us the following small but significant differences between methperchlorate and methiodide of III. (1) The IR region of the so called “truns” band [ 12-151 (2800-2600 cm-‘) in normal and deuterated preparations of the methiodide of III are identical which unequivocally indicates that deuteration does not affect the protons around N(1) atoms; hence two additional unexpected VC.-n bands at 2180 and 2090 cm-’ must also be connected with the vibration of N+-CD3 groups. If so, this is a very rare and new case in which the stretching vibration of one N+-CD3 group gives rise to four well separated bands (two doublets at 2295/2260 and 2180/2090 cm-‘). For this phenomenon we found only one reasonable explanation. The rotating N+-CH3 groups interact intramolecularly with the free electron pair of the N(1) atom by two different modes: (i) the orientation of three C(18)-H bonds relative to the three C-N( 16) bonds is staggered (form A in Scheme 2) but in consequence, the H atom from one C(lS)-D bond is much too close to the N(1) atom, so both atoms, before forming a relatively strong quasi hydrogen bond, have to repel each other which introduces some intrinsic strain into that form of cation;
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(ii) the orientation of three C(18)-H bonds towards three N(16)-C bonds results in a thermodynamically unfavourable eclipsed form (B in Scheme 2) which, however, being without intrinsic strain is additionally stabilized by two weak quasi hydrogen bonds. We assume that both forms are either frozen in the crystal lattice or are in slow equilibration which is visible on the IR time-scale. If our explanation for the presence of two doublets of bands in the IR region of Vc-n is correct, and the predicted equilibrium between two rotamers (staggered A and eclipsed B in Scheme 2) is thermodynamically controlled, the enthalpy difference between rotamers A and B should have a small negative value since double bands at 2295/2260 cm-’ are significantly more intense than those at 2180/2090 cm-’ (see Fig. 4). (2) In the above IR region of the methperchlorate of III (see Fig. 4), there are also two pairs of bonds having shape, relative intensity and localization similar to those of the methiodide of III. Very small shifts of all four bands by 3-5 cm-’ to longer wavelengths seems to indicate that both types of hydrogen bonding are a little stronger in methperchlorate than in methiodide, probably because iodide anions, due to their different shape and proton acceptor activity, do not interact with IIICDf cations in the same manner as perchlorate anions. This can be seen even better in the “tram” band region of the IR spectra of methperchlorate and methiodide of III (Fig. 4). There are some significant differences, not only between methperchlorate and methiodide, but also between normal and deuterated preparations of methperchlorates, although in this case the differences are much smaller. Comparative observations of the shape and intensities of the “trans” band regions from the above two quaternary salts of III and of the free base of III and its 2-0~0 derivatives unequivocally indicate that iodide anions do not change it whereas perchlorate anions do. Similar conclusions were drawn from differences in the “trans” band region of ICH: * X(X- = I-, ClO:) [ 41 where the N+--CH3 groups are easily accessible for direct interaction with counteranions, but the explanations of both phenomena must be different. In the latter case it was reasonable to assume on the basis of X-ray data [4] that due to the direct dimeric mode of interaction of one perchlorate anion with geminal C-H bonds from N+--CH3 groups, the boat conformation of ring C was significantly deformed. In consequence, two axially oriented hydrogen atoms from C( 17) and C( 11) interact in an “anti Hamlow” [4] manner with antibonding orbitals of C(lO)-H and C(6)-H bond which are responsible for the shape and intensities of the “trans” bond. For steric reasons a similar explanation could not be adopted for both quaternary salts of III, and there being no X-ray data for the molecular and crystal structures of IIICH:. I- and IIICH:. ClO; we can now present only a tentative explanation as to why perchlorate does and iodide anions do not change the “tram” band in IIICH; cations. In the case of IIICH; cations the quaternary N+--CH3
201
Scheme
2
groups are cisoidal to the basic N(1) atoms, interacting with that accepting center by hydrogen bonding modes. As has already been mentioned, from the localization of two pairs of C-D bands we assume that type of intramolecular hydrogen bond to be stronger in the case of IIICH:. ClO;, and in consequence, stronger participation of the free electron pair of the N(1) atom in methperchlorate is responsible for significant changes in the shape and intensity of its “truns” bands. We could, however, accept another explanation; namely directed interaction of perchlorate anions with C-H bonds which are responsible for the “trans” band (and their antibonding orbitals) in the anti “Hamlow” style. Most probably both factors discussed above diminish the shape and intensity of the “truns” band in methperchlorate of III. We hope that our studies now in progress on the nature of the “truns ” band will also answer these questions. We also hope that the hypothetical explanation for the presence of two pairs of ~c_n bonds in the IR spectra of IIICH: * X- presented in this paper will be
208
unequivocally nary N-methyl
solved by our further study on the stereochemistry cations of quinolizidine derivatives.
of quater-
ACKNOWLEDGMENTS
We thank Dr. T. Lis of Wroclaw University for rendering the computer accessible to us and for his help in calculating the structure of 2-oxosparteine methperchlorate. REFERENCES 1 R. Mosquera, L. Castedo and I. Ribas, Ann. Quim., 70 (1974) 609. 2 L. Castedo, I. Ribas and R. Riquera, Acta Cient. Compostelana, 11(l) (1974) 23. 3 K. Langowska, J. Skolik and M. Wiewiorowski, Bull. Acad. Pal. Sci., Ser. Sci. Chim., 25 (1977) 11. 4U. Majchrzak-Kuczynska, A. E. Koziol, K. Langowska and M. Wiewiorowski, Bull. Acad. Pol. Sci., Ser. Sci. Chim., 32 (1984) 233-253. 5 H. Maluszyiiska, A. Hoser and Z. KaIuski, Acta Crystallogr., Sect. B, 35 (1979) 910. 6 M. S. Lehman, F. K. Larsen, Acta Crystallogr., Sect. A, 30 (1974) 580. 7 M. Jaskolski, Ph.D. Thesis, Adam Mickiewicz University, Poznan, 1979. 8 Syntex XTL, Operation Manual, Cupertino: Syntex Analytical Instruments, 1973. 9 International Tables for X-Ray Crystallography, Vol. IV, The Kynoch Press, Birmingham, 1974. 10 S. C. Nyburg, Acta Crystallogr., Sect. B, 30 (1974) 251. 11 W. L. Duax and D. A. Norton, Atlas of Steroid Structure, Vol. 1, Plenum, New York, 1975. 12 J. Skolik, P. J. Krueger and M. Wiewiorowski, Tetrahedron, 24 (1968) 5439. 13 H. P. Hamlow and S. Okuda, Tetrahedron Lett., (1964) 2553. 14 L. J. Bellamy and D. W. Mayo, J. Phys. Chem., 80 (1976) 80. 15M. D. Bratek-Wiewiorowska, U. Rychlewska and M. Wiewiorowski, J. Chem. Sot., Perkin Trans. 2, (1979) 1469.