Organometallics 1986, 5, 85-89 have an elongated C1-C3 bond. Somewhat surprisingly, the lithium salt of the "antiaromatic cyclopropenyl anion" is not indicated t o be particularly unstable thermodynamically. The lowest energy 3-cyclopropenyllithium form, singlet 5 with C, symmetry, has about the same methyl stabilization energy as that of, e.g., 2-propyllithium. This possibility was considered by Wasielewski and B r e ~ l o wand ~ ~ is due to compensating factors: some residual 4ae destabilization is balanced by the stabilization due to small-ring rehybridization and the u inductive effects of the double bond. Nevertheless, manifestations of the expected Huckel4a electron antiaromaticity are quite clearly evident in the strong distortions from planarity exhibited both in the singlet 5 and in the triplets 6 and 7. These triplets are estimated to be about 10 kcal/mol less stable than the singlet 5. Breslow has measured the rates of base-catalyzed deuterium exchange in comparably substituted cyclopropyl and cyclopropenyl systems. The latter exchanged about 60003" Yo 100003b times slower than the corresponding cyclopropane, thus indicating some destabilization of cyclopropenyl anion systems. With the assumption that kinetic acidities parallel thermodynamic acidities2 an energetic difference for the proton abstraction of 5.2-6.1 kcal/mol can be evaluated. This is in reasonable good agreement with our calculated value of 3.7 kcal/mol (eq
85
3).34
Acknowledgment. This work was supported at Erlangen by the Fonds der Chemischen Industrie and the Deutsche Forschungsgemeinschaft. We also appreciate the assistance of the Regionales Rechenzentrum Erlangen and the Rechenzentrum der Universitiit Graz. Registry No. 11213, 20829-57-6; 4, 98705-30-7; 51617, 72507-54-1; 8, 98705-27-2; 9, 98705-28-3; 10, 4529-04-8; 11, 51760-92-0;12,51174-22-2;13,19527-08-3;CH3Li,917-54-4;CH3-, 15194-58-8;ethynyllithium, 1111-64-4;allyllithium, 3052-45-7; 2-propenyllithium, 6386-71-6; vinyllithium, 917-57-7; cis-lpropenyllithium, 6524-17-0;trans-1-propenyllithium, 6386-72-7; methyllithium, 917-54-4; cyclopropyllithium, 3002-94-6; 1propyllithium, 2417-93-8;ethyllithium,811-49-4;2-propyllithium, 1888-75-1; (1,2,3-triphenylcyclopropenyl)lithium,98705-29-4; ethynyl anion, 29075-95-4; 1-propynl anion, 31139-07-8;allenyl anion, 64066-06-4; allyl anion, 1724-46-5; 2-propenyl anion, 65887-19-6;Vinyl anion, 25012-81-1;1-propenyl anion, 65887-20-9; cyclopropyl anion, 1724-45-4; 1-propyl anion, 59513-13-2;ethyl anion, 25013-41-6; 2-propyl anion, 25012-80-0. Supplementary Material Available: Tables of fractional coordinates and interatomic distances ( 5 pages). Ordering information is given on any current masthead page. (34) In a later study using indirect methods, Breslow was able to estimate the pK, of unsubstituted cyclopropene to be 61.3.3c However, no comparable value for the pK, of cyclopropane is available.
Organotin Biocides. 4. Crystal and Molecular Structure of Tricyclohexylstannyl 3-Indolylacetate, Incorporating the First Monodentate Carboxylate Group Bonded to a Triorganotin( I V ) Kieran C. Molloy" and Thomas G. Purcell School of Chemical Sciences, National Institute for Higher Education, Glasnevin, Dublin 9, Ireland
Ekkehardt Hahn and Herbert Schumann* Institut fur Anorganischs und Analytsche Chemie, Technische Universitat, Strasse des 17 Juni 135, 0-1000Berlin 12, FGR
J. J. Zuckerman" Department of Chemistry, University of Oklahoma, Norman, Oklahoma 730 79 Received October 4, 1984
The crystal and molecular structure of tricyclohexylstannyl3-indolylacetate[ (CBH11)3Sn02CCH2(C8&N)] is reported. Cr stal data (150 K): space group P212121;a = 16.487 (6) A, b = 10.674 (4) A, c = 14.804 ( 5 ) A; V = 2605.2 Z = 4; Pcalcd = 1.382 g ~ m - ~For . 2091 observed reflections [I I2a(1)] R = 0.0351 and R , = 0.0248. The molecule incorporates a monodentate carboxylate ligand and a tetrahedral geometry at tin. Intermolecular NH-OC hydrogen bonds propagate through the lattice to produce a "S"-shaped polymer from which the tricyclohexyltin(1V) moiety is pendant.
i3,
Introduction Organotin compounds are now the active components in a number of biocidal formulations, finding application in such diverse areas as fungicides, miticides, molluscicides, marine antifouling paints, surface disinfectants, and wood preservatives.2 It is currently of interest to us3 to prepare (1) Author to whom correspondence should be addressed, at current address: School of Chemistry, University of Bath, Claverton Down, Bath BA2 IAY,U.K. (2) Davies, A. G.; Smith, P. J. In "Comprehensive Organometallic Chemistry";Wilkinson,G., Stone, F. G. A., Abel, E. W., Eds.; Pergammon Press: Oxford, 1982; Vol. 2, p 519.
and structurally characterize novel compounds in which the active organotin moiety is bound to a substrate which is itself active, in the hope that a combination of complimentary properties might enhance the effectiveness of the whole unit. In particular, our work is centered on derivatives of the R3Sn residue, which are now established as having the most favorable activity patterns, and specifically in this report the tricyclohexyItin compounds (3) (a) For previous parta to this series, see: Burke, N.; Molloy, K. C.; Purcell, T. G.; Smyth, M. R. Znorg. Chim. Acta 1985, 106, 129. (b) Molloy, K. C.; Zuckerman, J. J. Acc. Chem. Res. 1983, 16, 386.
0276-7333/86/2305-0085$01.50/0 0 1986 American Chemical Society
86 Organometallics, Vol. 5, No. 1, 1986
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(Cy,SnX) which are potent acaricides while possessing tolerable mammalian t ~ x i c i t y . Two ~ of this class of compounds are currently marketed commercially, tricyclohexyltin hydroxide (Plictran, Dow Chemicals) and 1(tricyclohexylstannyl)-1,2,4-triazole (Peropal, Bayer A.G.) while a third, (0,O’-dialkyl dithiophosphato)tricyclohexyltin, is under patent.5 Indole-3-acetic acid (HIAA; 1) is a naturally occurring plant growth hormone which promotes cell enlargement in shoots and lateral root initiation. Its modus operandi C 27
I
is unproven but is thought to stimulate polysaccharide synthesis or in some way alter the properties of existing cell wall components so that the cell wall is “loosened”and enlargement made easier.6 In this paper we report the synthesis and X-ray crystallographic characterization of tricyclohexylstannyl 3indolylacetate, in which both acaricidal and growth hormonal properties are latent.
HI
Figure 1. ORTEP drawing of one molecule of (C6Hll),SnOC(0)CH2(C8HBN), showing the employed numbering scheme. The thermal ellipsoids enclose 50% of the electron probability distribution for all non-hydrogen atoms. H1 is drawn on an arbitrary scale; all other hydrogen atoms have been omitted for clarity.
Experimental Section General Data. 3-Indolylacetic acid was purchased from Aldrich and used without further purification. Infrared spectra were recorded on a Perkin-Elmer 1330 instrument; ‘H NMR were obtained at 60 MHz on a Perkin-Elmer R12B spectrometer. Details of our Mossbauer spectrometer and method of data collection and manipulation are described e l ~ e w h e r e . ~Microanalyses were carried out by the Microanalytical Service of University College, Dublin. Preparation of Tricyclohexylstannyl3-Indolylacetate.A solution containing tricyclohexyltin(1V) hydroxide (3.00 g, 7.8 mmol) and 3-indolylacetic acid (1.39 g, 7.9 mmol) in toluene (100 mL) was refluxed for 45 min, and the water formed was removed azeotropically by using a Dean and Stark apparatus. The solution was allowed to cool to ca. 55 “C, filtered, concentrated to ca. half its volume, and subsequently allowed to crystallize overnight a t 0 “C. The resulting crude, crystalline product was recrystallized from hot toluene to yield colorless crystals (1.25 g, 30%) of the title compound mp 150-152 “C; IR (KBr disk) 3295 br, 1615 cm-‘; IR (CHCl,) 3480,1635 cm-’; lH NMR (CDC1,) 6 1.55 (m, 33 H, (C&1)$n), 3.70 (s,2 H, 02CCH2),7.0-8.2 (m, 6 H, c&CcffNH); ‘19Sn NMR (CH3C6H,) 8 +5.1; Mossbauer spectrum, IS = 1.55 mm s-l, QS = 3.01 mm s-l, fwhh = 1.01 mm s?. Anal. Calcd for C28H41N02Sn:C, 62.00; H, 7.63; N, 2.58. Found: C, 62.18; H , 7.77; N, 2.52. Crystallographic Analysis. Crystals suitable for X-ray diffraction experiments were obtained through recrystallization from hot toluene. A crystal with the dimensions 0.32 X 0.40 X 0.20 mm was glued on top of a glass fiber and placed in the nitrogen stream of the diffractometer. Preliminary crystal analysis and final data collection were performed at 150 (3) K on a Syntex P21 automatic four-circle counter diffractometer fitted with a low-temperature device. The crystal system was determined by axial photography techniques to be orthorhombic. Final cell dimensions were obtained by least-squares refinement of the angular settings of 15 accurately centered reflections. The intensities of all reflections with 26’ < 50” were measured by using 1”w scans. Two reflections were used as standard, and their intensities were monitored after each 50 observations. No significant changes in the intensities of the monitor reflections were noted. (4) Evans, C. J. Tin I t s Uses 1970, 110, 6. (5) Baker, D. R. U S . Patent, 3919418, 1975; Chem. Abst. 1976, 84. F 44_ . _1l.5 _6_
(6) Corbett, J. R. “The Biochemical Mode of Action of Pesticides”; Academic Press: New York, 1974. (7) Molloy, K. C.; Purcell, T. G.; Quill. K.; Nowell, I. W. J . Organomet. C h e m . 1984,267, 237.
Figure 2. Stereoview of the packing, viewed down the b axis. The raw data were converted to F, values after correction for Lorentz and polarization effects. The esd’s, Q, were based upon counting statistics. Due to the regular shape of the data crystal and the low absorption coefficient, no absorption correction was made (M = 9.10 cm-’; the minimum and maximum transmittances are 0.69 and 0.83, respectively). Additional crystal and data collection details are summarized in Table I. Structure Solution and Refinement. From the systematically absent reflections the space group was determined to be P212121(no. 19). The position of the tin atom was calculated from a three-dimensional Patterson map. A difference Fourier map based on the heavy-atom phases revealed the positions of all other non-hydrogen atoms. These atoms were refined in stages by using first isotropic and latter anisotropic thermal parameters. All hydrogen positions were calculated (d(C-H) = 1.08 A) but only the positional parameters of H1 (bonded to N) were refined in the least-squares procedure. The isotropic temperature factor for all hydrogens was held constant a t U = 0.05 A2. The maximum parameter shifts in the final cycle of refinement were 0.001 of their estimated standard deviations. A difference Fourier map calculated from the final structure factors showed no features greater than 0.44 e/A3. The strongest peaks in this map were located in the vicinity of the tin atom. The final R value is 0.0351 for the 2091 reflections (Z > 2a(Z)) included in the least-squares sums (R, = 0.0248). The correct enantiomer for the crystal selected was established by comparison of the R values for each of the two possibilities. All calculations were performed by using the program SHELX.~ Atomic scattering factors for C, N, and 0 were obtained from ref 9 and those for S n from ref 10. The Af ’ and A/’ ” components (8) Sheldrick, G. M. “SHELX 76 System of Programs”, 1976. (9) Cromer, D. T.; Mann, J. B. Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 1968, A24, 321. (10) Cromer, D. T.; Mann, J. B. Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. G e m Crystallogr. 1968 A24, 390.
Organotin Biocides
Organometallics, Vol. 5, No. 1, 1986 87
Table I. Crystal and Data Collection Parameters for (CBH~~)~S~OC(O)CHZ(CBH,N)" formula fw, dalt
C28H41N02Sn 542.30 a, A 16.487 (6) b, A 10.674 (4) c, 8, 14.804 (5) v, A3 2605.2 z 4 space groupb ~12121 Pcaledt g/cm3 1.382 p, cm-' 9.10 F(000) 1128 Mo K a , 0.71069 radiation, A, 150 (3) temp, K scan technique W-29 28 limit, deg 50 data collected 0 - 4 , 0-k, 0-4 no. of data collected 2329 no. of unique data 2306 no. of observed data 2091 ( I 2 2u(Z)) 0.0351 R = ~ l l ~ -nI~ell/CI~nI l R, = [CwllF0l- IFc112/C~lFolz]1'2 0.0248 1~ = 2.5339/(uP)' no. of parameters 292 a Estimated standard deviations of the last significant digit are given in parentheses. No. 19 in: "International Tables for X-ray Crystallography"; Kynoch Press: Birmingham, U.K., 1976.
Sn-C(1) Sn-C(7) Sn-C (13) Sn-O(1) O(l)-C(19) 0(2)-C(19) C(19)-C(20) C(2O)-C(21) C(21)-C(22) C(22)-N C(23)-N H(l)-N C(23)-C(24) C(24)-C(21) C(24)-C(25) C(25)-C(26) C(26)-C(27) C(27)-C(28) C(28)-C(23)
Intramolecular Bond Distances 2.161 (6) C(l)-C(2) 2.147 (5) C(2)-C(3) 2.165 (6) C(3)-C(4) 2.086 (3) C(4)-C(5) 1.302 (7) C(5)-C(6) 1.213 (7) c(6)-C(1) 1.538 (8) C(7)-C(8) 1.489 (9) C(8)-C(9) 1.374 (8) C(9)-C(lO) 1.365 (8) C(lO)-C(ll) 1.377 (8) C(ll)-C(l2) 0.88 (6) C(12)-C(7) 1.398 (8) C(13)-C(14) 1.425 (9) c(14)-C(15) 1.415 (9) c(15-C(16) 1.357 (8) c(16)-C(17) 1.395 (9) C(17)-C(18) 1.383 (9) c(18)-C(13) 1.380 (9)
1.529 (8) 1.514 (8) 1.522 (7) 1.510 (8) 1.525 (8) 1.550 (8) 1.521 (7) 1.523 (8) 1.489 (9) 1.517 (8) 1.539 (8) 1.530 (8) 1.537 (7) 1.508 (8) 1.519 (8) 1.530 (8) 1.514 (8) 1.536 (7)
Intermolecular Bond Distances H(1)-0(2)'b 2.00 (6) "Estimated standard deviations of the last significant digit are given in parentheses. *Primed atoms represent transformed coordinates of the type -1 - x , ' I z+ y, -'I2 - 2.
Table 11. Final Positional Parameters for (C6H11)3SnOC(0)CHz(CaH~N) (X104)" atom
X
Y
2
-2379.8 (2) -3328 (4) -3632 (4) -4244 (4) -4950 (4) -4659 (4) -4049 (4) -1209 (3) -565 (4) 173 (4) 115 (4) -413 (4) -1258 (4) -2264 (4) -3014 (4) -2870 (4) -2634 (4) -1890 (4) -2040 (4) -2565 (2) -3691 (3) -3255 (4) -3506 (4) -3922 (5) -4746 (5) -4905 (4) -539 (4) -4815 (5) -3561 (5) -2751 (5) -2622 (6) -3259 (6) -4060 (5)
-1742.1 (4) -530 (6) 362 (7) 1288 (6) 628 (6) -246 (7) -1197 (6) -866 (6) -1459 (7) -832 (8) 546 (7) 1164 (7) 552 (7) -3714 (5) -4290 (6) -5645 (6) -6400 (5) -5846 (6) -4486 (6) -1648 (4) -2720 (4) -2131 (6) -1822 (7) -583 (7) -394 (7) 856 (6) 118 (6) 1507 (7) 624 (7) 1054 (8) 2299 (9) 3155 (8) 2774 (7)
-4092.6 (3) -4593 (4) -3859 (4) -4227 (5) -4688 (4) -5422 (4) -5061 (4) -4038 (4) -3336 (5) -3312 (6) -3169 (4) -3880 (5) -3897 (5) -4410 (4) -4865 (4) -5105 (4) -4277 (4) -3806 (4) -3570 (4) -2700 (2) -2958 (3) -2453 (5) -1477 (4) -1489 (4) -1504 (4) -1584 (4) -165 (4) -1638 (4) -1574 i4j -1634 (4) -1752 (4) -1811 (4) -1756 (4)
"Estimated standard deviations of the last significant digit are given in parentheses. H1 is bonded to N and is the only hydrogen atom with refined positional parameters. Positional parameters for H1 are multiplied by lo3. of anomalous dispersion for S n are from ref 11. Final atomic positional parameters are listed in Table 11. T h e atomic numbering scheme followed in these listings is identified in Figure 1. Figure 2 shows a stereoview of the packing. A stereoview of (11)Cromer, D. T.; Liberman, D. J. Chem. Phys. 1970,53, 1891.
C(1)-Sn-C(7) C(l)-Sn-C(13) C(1)-Sn-0 (1) C(7)-Sn-0(13) C(7)-Sn-0( 1) C(13)-Sn-O(1) Sn-O(l)-C(lS) O(l)-C(19)-0(2) O(l)-C(19)-C(20) 0(2)-C(19)-C(20) C(19)-C(2O)-C(21) c(2O)-C(21)-c(22) C(21)-C(22)-N C(22)-N-C (23) C(22)-N-H(1) C(23)-N-H(1) N-C(23)-C(24) C(23)-C(24)-C(21) c(24)-C(21)-c(22) C(24)-C( 21)-C(2O) C(23)-C (24)-C (25)
N-Hl-Oz'b
Intramolecular Angles 113.7 (2) C(24)-C(25)-C(26) 124.9 (2) c(25)-C(26)-C(27) 101.7 (2) C(26)-C(27)-C(28) 110.6 (2) C(27)-C(28)-C(23) 94.2 (2) C(28)-C(23)-C(24) 105.9 (2) C(l-)C(2)-C(3) 112.8 (4) C(2)-C(3)-C(4) 123.3 (6) C(3)-C(4)-C(5) 114.5 (6) C(4)-C(5)-C(6) 122.1 (7) C(5)-C(6)-C(l) 107.6 (5) C(6)-C(l)-C(2) 125.9 (7) C(7)-C(8)-C(9) 109.6 (7) C(8)-C(9)-C(lO) 109.4 (6) C(9)-C (10)-C( 11) 125 (4) C(lO)-C(II)-C(I2) 125 (4) C(ll)-C(12)-C(7) 106.9 (6) C(12)-C(7)-C(8) 108.0 (7) C(13)-C(14)-C(15) 106.2 (7) C(14)-C(15)-C(16) 127.7 (7) C(15)-C(16)-C(17) 118.2 (7) C(16)-C (17)-C (18) C(17)-C(18)-C(13) C(18)-C(13)-C(14) Intermolecular Angles 163 (4) H1-02'-C19'
118.3 (9) 122.1 (9) 121.5 (8) 116.0 (8) 124.0 (8) 111.6 (5) 111.7 (5) 111.4 (5) 111.6 (5) 110.8 (5) 110.7 (5) 111.8 (5) 112.3 (6) 111.6 (6) 110.2 (6) 112.0 (5) 110.5 (6) 111.1 (5) 111.1 (5) 111.6 (5) 110.2 (5) 111.5 (5) 109.5 (5)
158 (4)
"Estimated standard deviations of the last significant digit are given in parentheses. *Primed atoms represent transformed coordinates of the type -1 - x , + y , -'I2- t. a part of the infinite helix formed by the title compound is shown in Figure 3. Interatomic distances and angles are listed in Tables I11 and IV, respectively. Tables of thermal parameters, hydrogen positions, least-squares planes, and tables of observed and calculated structure factor amplitudes are available (see supplementary material).
Results and Discussion The local geometry at tin in the asymmetric unit is shown in Figure 1,and the bond lengths pertinent to the discussion of this structure are given in Table V, along with
88 Organometallics, Vol. 5, No. 1, 1986
Molloy et al.
Figure 3. Stereoview of the helix, viewed down the z axis (plotting range; x , 0.0-1.0;y, -1.0 to 1.0;z,0.0-0.5). The cyclohexyl groups bound to tin have been omitted for clarity.
Table V. Structural Data (A) for Selected Organotin Carboxvlates" compd Sn-O(l) Sn-0(2) (CfiHJ'UeH2C02Hb (C6H,,)3SnOz2.086 (3) 2.929' CCH2(C8H,N)d (C&11)$n02CCH3 2.12 (3) 3.84h (C,H,,),SnO,)CCF, (C6H&Sn02CCcH,(NvR-o)J (CH&SnO,CCHzNH,'
2.08 (4)
3.7@
2.070 ( 5 ) 2.463 (7)' 2.21 (1) 3.23 ( 2 P
O(1) 1.223. 1.298 1.213 ( 7 ) , 1.302 ( 7 ) 1.25 (9), 1.39 ( 8 ) 1.20 ( 5 ) , 1.28 (4) 1.224 ( S ) , 1.2.96 ( 8 ) 1.23 (3), 1.34 (3)
CO***N 2.66F 2.8511
2.94 (1)"' 2.74 (3)
a A fuller listing of organotin carboxylate data is given in ref 7. bReference 12. cCO-.O. dThis work. eIntramolecular. fN-H(1) = 0.88 (6) A; H(1)-0(2') = 2.00 (6) A;LN - H(1)-0(2') = 163 (4)'. If N-H(l) is extended along its vector to 1.03 A, the remaining values above become 1.85 A and 162O, respectively. gReference 13. Intermolecular. 'Reference 14. 1 Reference 15; R = 2-hydroxy-5methylphenyl. The structure also includes N-OH and CO-N interactions at 2.58 (1) A, forming a three-center hydrogen bond. Reference 17.
selected data for other organotin carboxylates for comparison. The environment of the metal is best described in terms of a tetrahedral arrangement of ligating atoms in which the carboxylate group bonds in a monodentate fashion. The intramolecular spacial disposition of the carbonyl oxygen 0(2), 2.929 A,from tin is within the sum of the respective van der Waal's radii (3.70 A) and moreover is almost certainly in part responsible for the opening of the ~C(l)-Sn-C(13) to 124.9 (2)'. However, we believe that this distortion arises from steric rather than electronic factors and that the number of bonds to tin does not expand beyond four. The following three arguments support this assertion. First, despite the opening of the LC(1)Sn-C(13), there is no systematic change in bond angles which would indicate conversion to a trigonal bipyramidal (tbp) geometry with O(2) and C(7) in the axial sites and 0(1),C(l), and C(13) forming the equatorial girdle. For example, the angles C(7)-Sn-C(1) and C(7)-Sn-C(13) would both be expected to close from 109'28' toward 90' but in fact open slightly to 113.7 (2) and 110.6 (2)', respectively. In fact, all the angles about tin can be rationalized simply in terms of an isovalent rehybridization at the metal which concentrates p orbital character in the bond to the more electronegative O(1) and s character in the bonds to carbon, resulting in a closing of those angles involving O(1) (94.2, 101.7, 105.9') and concomitant opening of the angles between carbon atoms (110.6,113.7, 124.9'). In addition, the Sn-C(7) bond ostensibly trans to the approach of O(2) [~C(7)-Sn-0(2)= 142.9'1 is the
shortest [2.147 (5) A] of the three Sn-C interactions rather than the longest as would be expected from an axial tbp site. Secondly, the s u m of the angles at tin involving O(l), C(l), and C(13) totals 332.5', compared with values of 328.5' and 360' for regular tetrahedral and tbp geometries, respectively. Finally, the C(19)-O(l) [1.302 (7) A] and C(19)=0(2) [1.213 (7) A] bonds retain the integrity of their single- and double-bond character consistent with the strength of the Sn-O(1) bond [2.086 (3) A] which is at the short end of the range for such interactions (2.07-2.21 A7). In fact, the C(19)=0(2) bond is even shorter than in the parent 3-indolylacetic acid (1.223 A),12 where a stronger array of hydrogen bonds operates (vide infra). Comparison can be drawn with two other tricyclohexyltin carboxylates, Cy3Sn02CCH313 a n d Cy3Sn02CCF,.14 Both of these compounds are associated in the solid state by a bridging, bidentate carboxylate moiety,15 to form polymers of flattened "S" (class 3 9 construction. Although the intermolecular interactions are weak (Table V), they clearly distort the bond angles at tin systematically toward tbp geometry, in which the axial sites are occupied by the two oxygen atoms of the bridging ligand. A closer analogy to the molecular structure of the title compound is that of Ph3Sn0,CC6H,(NR2-o) (R = 2-hydroxy-5-methylphenyl),15 which forms discrete, fivecoordinate, cis-R3Sn02 monomeric units, in which the bidentate carboxylate group spans axial and equatorial sites of the tbp geometry. The Sn-0(2) intramolecular interaction in this compound is significantly stronger [2.463 (7) A] than in the 3-indolylacetic acid derivative, presumably a consequence of an enhanced Lewis acidity a t tin resulting from bonds to three electron-withdrawing phenyl groups rather than three electron-donating cyclohexyl units in our system. The only other organotin carboxylate structure incorporating a monodentate RC02 moiety is (CH3),Sn02CCH2NH2,17but a tbp geometry at tin still arises by virtue of a bridging N-Sn bond. We believe that the structure of the title compound thus represents the first crystallographically authenticated example of a genuine tetrahedral organotin carboxylate. The lattice structure of (C6H1J3SnIAA comprises of chains of molecules linked intermolecularly by hydrogen bonds which join NH-O=C subunits of the 3-indolylacetate ligand (Figure 2). The resulting polymer propagates through the crystal in a helical fashion along the 21 axis parallel to b (Figure 3), and whose construction is aided by the intra- and intermolecular dihedral angles between C8H6N and cco2planes of 102' and 66', respectively (Table VIII, supplementary material). The N-H(l) and H(1)-0(2') distances are found experimentally to be 0.88 (6) and 2.00 (6) A and are not colinear, the ~N-H(1)-0(2') being 163 (4)'. However, if the N-H(l) bond length is unormalizedn18by moving H(1) along the N-H(1) vector to a standard N-H bond length (1.03 A), the H(1)-O(2') length becomes 1.85 A and the LN-H(1)-O(2') = 162'. The hydrogen bond is thus quite strong as measured in comparison to the average intermolecular H-0 distance of 1.895 %, (for 1112 organic compounds (12)Karle, I. L.; Britts, K.; Gum, P. Acta Crystallogr. 1964,17,496. (13)Alcock, N.W.;Timms, R. E. J. Chem. SOC.A. 1968,1876. (14)Calogero, S.;Ganis, P.; Peruzzo, V.; Tagliavini,G. J. Organomet. Chem. 1980,191,381. (15) Harrison, P. G.; Lambert, K.; King, T. J.; Magee, B. J . Chem. SOC.,Dalton Trans. 1983,363. (16)Molloy, K.C.;Quill, K. J. Chem. SOC.,Dalton Trans. 1985,1417. (17)Ho,B. Y. K.; Molloy, K. C.; Zuckerman, J. J.; Reidinger, F.; Zubieta, J. A. J. Organomet. Chem. 1980,187, 213. (18)Jeffrey, G.A,; Lewis, L. Carbohydr. Res. 1978,60, 179.
Organotin Biocides surveyed), while the angle of approach of the two halves of the bond is typical (mean LN-H-sO = 163.5O) of such systems.lg The effect of organostannylation of 3indolylacetic acid on the latter's lattice structure is thus to convert a dimeric OH-OC (0-0 = 2.665 A") moiety into a NH-OC polymer from which the (C6H11)3Sn moiety is pendant. It is worth concluding by emphasizing the effect of hydrogen bonding on the structure of organotin compounds and in particular in the present context organotin carboxylates. The structure which dominates this compound class is that of a carboxylate-bridged polymer, propagating in a "S"fashion through the lattice. Several variations within this theme exist, such as weak (Cy3Sn02CH313)or strong (Me3Sn02CH320) bridging bonds and coordination numbers a t tin of either five20 or six (Ph3Sn02CCH3,7 Me2C1SnO2CCH,2l). Of the structures which deviate from this theme, hydrogen bonding involving the carbonyl oxygen is commonly observed. For example, in addition to Me3Sn02CCH2NH2"which retains a polymeric structure through H2N:+Sn bridges, a number of five-coordinated triphenyltin complexes embodying a chelating carboxylate group have now been characterized, namely, Ph3Sn02CC6H4(N2R-o),15a n d more recently ~ ~- N H ~P ,- ~N~H , ~ ~all ) , of ~~ Ph,Sn02CC6H4X(X = o - O H , O (19) (a) Taylor, R.; Kennard, 0.;Werner, V. J. Am. Chem. SOC.1983, 105, 5761. (b) Taylor, R.; Kennard, 0.; Werner, V. J. Am. Chem. SOC., 1984, 106, 244. (20) Chih. H.: Penfold. B. R. J. Crvst. Mol. Struct. 1973. 3. 285. (21) Allen, D: W.; Nowell, I. W.; Brooks, J. S.; Clarkson, Rl W. J. Organomet. Chem. 1981,219, 29. (22) Vollano. J. F.:Day, R. 0.:Rau. D. N.: Chandrasekhar.. V.:. Holmes. R. R. Inorg. &em. igsb,'23, 3153. (23) Swisher, R. G.;Vollano, J. F.; Chandrasekhar, V.; Day, R. 0.; Holmes, R. R. Inorg. Chem. 1984,23, 3147.
Organometallics, Vol. 5, No. 1, 1986 89 which incorporate this feature. While we are not suggesting that hydrogen bonding is a prerequisite for a non-carboxylate-bridgedstructure, indeed three structures now contradict such a requirement and form five-coordinate, carboxylate-chelated triphenyltin species, [Ph3Sno2CC6H4X;X = o-OMe,22o - N M ~ ~ , ~ ~ it clearly plays a major role in influencing the final crystal and molecular structure. Acknowledgment. T.G.P. thanks the Department of Education (Ireland) for support in the form of a studentship. The wc-k nf H.S. is supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie. The work of J.J.Z. is supported by the Office of Naval Research. We would like to thank Dr. S. Blunden (International Tin Research Institute, Greenford) for recording the l19Sn NMR spectrum. Registry No. 1, 87-51-4; (CsHlI),SnOC (O)CH2(CBHsN), 98737-09-8; tricyclohexyltin(1V) hydroxide, 13121-70-5.
Supplementary Material Available: Tables of thermal parameters (Table VI), hydrogen atom positions (Table VII), and least-squares planes (Table VIII) and a listing of observed and calculated structure factor amplitudes (15 pages). Ordering information is given on any current masthead page. (24) The authors describe all the stated compounds as having fivecoordinate tin atoms in the solid state and, by consistencyof the infrared spectra as Nujol mulls or CCl, solutions, in solution also. Our interpretation of these data is that distortions from tetrahedral geometries are minor, although the relevant bond angles at tin do not follow a simple rehydridization within a tetrahedral geometry either. While the data appear more ambiguous in the assignment of coordination number at the metal than in the title compound, l19Sn NMR data for representative samples, e.g., Ph3Sn02CCsH40Me,S -119.9% are consistent with a coordination number at tin of four in solution and, by implication from the infrared data, the solid state as well. (25) Molloy, K. C.; Quill, K.; Blunden, S. J.; Hill, R. Polyhedron, in press.
