Organometallics 1987, 6, 2471-2478
2471
Methyltin( I V ) Structure Determination by NMR. X-ray and NMR Structural Analyses of Three Me,Sn(chelate), Compounds Bearing Five-Membered Chelate Ringst Thomas P. Lockhart' and Fredric Davidson E. I . du Pont de Nemours and Company Central Research Department, Experimental Station, Wilmington, Deb ware 19898 Received January 5, 1987
X-ray crystallography and solution and solid-state NMR studies have been carried out on three Me2Sn(chelate)zcomplexes bearing five-membered chelate rings in order to investigate the accuracy and reliability of previously reported empiricalcorrelationsof I1J('l%n,'%)( and 12J(119Sn,lH)I with the Me-Sn-Me angle. All six-coordinate MezSn(chelate)zcompounds bearing five-membered chelate rings examined to date deviate substantially from the empirical correlations; in contrast, all those examined bearing fouror six-membered chelate rings are well-behaved. X-ray crystallographic studies of MezSn(tropolonate)2 (1) have revealed the existence of a new crystallographic form: space group P2Jc; a = 10.732 (2) A, b = 14.181 (2) A, c = 10.574 (2) A; (Y = y = 90°, a = 98.18 (1)'; 2 = 4;R refiied to 0.059 (R, = 0.062). Molecules of 1 adopt a distorted cis-dimethyl octahedral geometry, with LMe-Sn-Me = 107.9 (6)'. Me,Sn(bojate) .MeOH (2) crystallies with two independent molecules in the w i t celk space group R1/n; a = 10.253 (1) b = 25.834 (2) A, c = 13.151 (2) A; CY = y = 90°, 0 = 103.82 (1)'; 2 = 4; R refined to 0.039 (R, = 0.039). Me2Sn(picolinate)2(3) crystallizes as a polymer with dimethyltin coordination number 7: space group P2,/c; a = 12.409 (1)A, b = 8.922 (6) A, c = 14.071 (3) A; CY = y = 90°, 0 = 110.06 (1)'; 2 = 4; R refined to 0.030 (A, = 0.036). Unusual solvent effects on molecular structure have been revealed by comparison of solution and solid-state NMR and X-ray crystallographic data.
1,
The possibility of using solid-state NMR to derive correlations between molecular structure and NMR parameters has been discussed in several recent Solid-state 13C NMR studies of crystalline methyltin(1V) compounds revealed a simple correlation (eq 1)between the magnitude of tin-carbon J coupling, J1J(11gSn,'3C)( (I'q),and the Me-Sn-Me angle, LMe-Sn-Me, for a wide variety of di- and trimethylti~~(IV)s.~*~ A quadratic expression (eq 2) describing the correlation of LMe-Sn-Me I'Jl = 10.7(~Me-Sn-Me) - 778 (1) LMe-Sn-Me = 0.0161(12J1)2- 1.32(I2Jl)+ 133.4 (2) and the two-bond tin-hydrogen J coupling, I2J('l9Sn,'H) I (I2JI), was derived i n d i r e ~ t l y . ~The close adherence to these relationships of NMR data for most compounds examined makes them quite useful for estimating LMeSn-Me in the solid-state and s o l u t i ~ n . ~ In some instances the correlations break down substantially, giving structural estimates as much as 10-20' in e r ~ o r . ~Two * ~ factors have appeared to be related to these deviationd the electronegativity of the ligands and the molecular structure (the two cis-dimethyl MezSn(chelate)2compounds e w i n e d show the largest deviation by far from eq 1). Poor understanding of the factors responsible for these deviations limits somewhat the practical utility of eq 1and 2 and encouraged a search for criteria that might indicate the reliability of LMe-Sn-Me estimates. In this regard, it was noted previ0usl9~that all compounds for which Me-Sn-Me angles estimated from solution llJl and 12Jl values differ by 8', or more, deviate strongly from eq 1. Examination of the literature revealed three structurally uncharacterized Me2Sn(chelate)2compounds with small I2Jl values, MezSn(tropolonate)2 (l), Me,Sn(k~jate)~ (21, and Me2Sn(picolinate)z(3),two of which have conflicting values of LMe-Sn-Me predicted from I1qand I2Jl in so+
Contribution No. 4258.
* To whom correspondence should be addressed at Eniricerche S.p.A., 20097 San Donato Milanese, Italy.
0276-7333/87/2306-2471$01.50/0
lution. Thus, they provide a test of the working hypothesis that such compounds will fail to obey the empirical NMR relationships. Additionally, they seemed to be likely candidates for the rare structural class of cis-dimethyl octahedral tin(1V) compounds.6 NMR and X-ray structural analyses of 1-3 are described in this paper. In ad-
1
2
3
dition to the above considerations, these compounds also provide interesting examples of medium effects on molecular structure and on the ability of combined solid-state and solution NMR measurements to reveal such effects.
Results and Discussion Structure of Me2Sn(tropolonate)2(1). NMR data for this compound are given in Table I. The discrepancy between fMe-Sn-Me estimated from solution I'Jl and 1 2 q 7 9 8 values (133' and 122', respectively), and the relatively small values of the coupling constants both suggested that 1might adopt a cis-dimethyl octahedral conformation. The solid-state llJl value, 635 f 20 Hz,is within experi(1) Manders, W. F.; Lockhart, T. P. J.Organomet. Chem. 1985,297, 143. (2) Lockhart, T. P.; Manders, W. F.; Zuckerman, J. J. J. Am. Chem. SOC.1985,107,4546. (3) Lockhart, T. P.; Manders, W. F. J. Am. Chem. SOC.,in press. (4) Lockhart, T. P.; Manders, W. F. Inorg. Chem. 1986,25, 892. (5) (a) Lockhart, T. P.; Manders, W. F.; Schlemper, E. 0. J. Am. Chem. Soe. 1985, 107, 7451. (b) Lockhart, T. P.; Manders, W. F.; Schlemper, E. 0.;Zuckerman, J. J. J. Am. Chem. SOC.1986,108,4074. (c) Lockhart, T. P.; Manders, W. F.; Holt, E. M. J.Am. Chem. SOC.1986, 108,6611. (6) A bibliography of organotin structural studies is given in: Smith, P. J. J . Organomet. Chem. Libr. 1981,12, 97, 321. (7) Komura, M.; Tanaka, T.; Okawara, R. Inorg. Chim. Acta 1968,2, 321. (8)Otera, J.; Hinoishi,T.; Kawabe, U.; Okawara, R. Chem. Lett. 1981, 273.
0 1987 American Chemical Society
2472 Organometallics, Vol. 6,No. 12, 1987
compd MezSn(tropolonate)2(1) Me,Sn(kojate), (2) Me,Sn(picolinate), (3)
Lockhart and Davidson
Table I. Solution and Solid-state IH,lac,and ll%n NMR Data for I, 2. and 3n solution NMR solv 119Snchem shift, ppm zJ(119Sn,lH), Hz 'J("BSn, 13C), Hz .. CDCl3 -197b 72.2b 643 DMSO-de -174.2 83.3b 746 DMF-d, -174.6 753 DMSO-$ -451 117.4 1154 CHBr3 83 i 2c
a Abbreviations: DMSO = dimethyl sulfoxide; DMF = N,N-dimethylformamide; av = average. graphically characterized modifications. Reference 8. dReported as 77.6 Hz in ref 15.
Table 11. Positional Parameters and Their Estimated Standard Deviations of Non-Hydrogen Atoms in Me2Sn(tropolonate)2(1)" atom X Y z B, A* 0.09247 (5) 0.77114 (6) 3.83 (1) Sn 0.77365 (6) 0.8796 (6) 3.8 (1) 0.0080 (4) 011 0.6591 (6) 0.7526 (7) 5.1 (2) 0.8289 (6) -0.0552 (5) 012 5.0 (2) 0.1180 (6) 0.6175 (7) 021 0.8793 (6) 0.5962 (7) 5,2 (2) 022 0.6551 (6) 0.0500 (6) 0.908 (1) 5.7 (3) 0.937 (1) 0.118 (1) C1 0.776 (1) 6.9 (4) C2 0.651 (1) 0.2095 (9) 0.8915 (9) 3.7 (2) 0.6820 (9) -0.0815 (7) C11 4.6 (2) -0.1351 (7) 0.970 (1) C12 0.616 (1) 6.6 (3) -0.2270 (9) 1.006 (1) C13 0.627 (1) 7.5 (4) -0.2992 (9) 0.967 (1) C14 0.703 (2) 0.883 (1) 6.2 (3) 0.789 (1) -0.2873 (8) C15 0.818 (1) 5.0 (3) 0.820 (1) -0.2121 (7) C16 0.8196 (9) 3.6 (2) 0.7810 (9) -0.1159 (7) C17 4.0 (2) 0.0909 (7) 0.504 (1) C21 0.8318 (9) 0.406 (1) 4.8 (2) 0.9046 (9) 0.0952 (9) C22 5.7 (3) 0.0751 (9) 0.277 (1) C23 0.875 (1) 5.3 (3) 0.0478 (9) 0.208 (1) C24 0.765 (1) 0.255 (1) 5.0 (3) 0.653 (1) 0.0281 (8) C25 4.2 (2) 0.0303 (8) 0.378 (1) C26 0.6286 (9) 4.0 (2) 0.0564 (7) 0.492 (1) C27 0.7021 (9) a Numbers in parentheses are estimated standard deviations in the least significant digits. Anisotropically refined atoms are given in the form of the isotropic equivalent displacement parameter defined as (4/3[a2B(1,1)+ b2B(2,2)+ d2B(3,3) + &(cos y)B(1,2) + ac(cos P)B(1,3) + bc(cos a)B(2,3)].
Figure 1. ORTEP plot of MezSn(tropolonate)2 (1) showing numbering scheme.
mental error of that found in solution, 643 Hz, strongly suggesting that the solid-state and solution structures of 1 are essentially the same. The X-ray structure of 1 was determined, and the positional parameters are given in Table I1 and selected bond angles and distances in Table 111. Figure 1 shows an ORTEP plot of the molecule. Compound 1 is monomeric in the solid state and, as predicted, adopts the unusual cis-dimethyl octahedral tin conformation, with LMe-Sn-Me = 107.9 (6)'. As for other six-coordinated cis-dimethyltin ~ornpounds,~ eq 1 and 2 fail for this compound. While most Me2Sn(chelate)2complexes have anisobidentically chelated ligands (cf. 2 below): each tropolonate
solid-state NMR 'J(ll9Sn, 13C),Hz 635 i 20 905 (av) 1155 f 20
Solid-state NMR of X-ray crystallo-
CZ
I3 (47)
018 (481
Figure 2. ORTEP plot and numbering schemes of one of two structurally distinct molecules of Me,Sn(kojate), (2) in the unit cell (numbers in parentheses refer to the second molecule of 2).
*
m
Figure 3. Packing diagram of 2 showing position of methanol solvent molecules in the crystal lattice.
ligand in 1 is nearly symmetrically bonded to tin: the range of D(Sn-0) = 2.140 (7)-2.193 (8)A and the range of D(C-O) = 1.27 (1)-1.30 (1) A. Most of the bond angles a t tin differ significantly from the ideal octahedral cis value of 90' and the trans value of 180'. The smallest cis angles are LO-Sn-0 of the chelating ligands [72.5(3)and 73.2 (3)'] and L021-Sn-012 [78.0(3)'J; the largest are LMeSn-Me [107.9(6)'] and LC1-Sn-011 [102.1(4)OI. The trans angles fall between 154.3 (3)' and 160.9 (1)O. Subsequent to our work with monoclinic 1 (obtained from ethanol solution) we became aware of an earlier X-ray structural studylo which reported that 1 crystallizes from a benzene-toluene solution in the triclinic space group P1 with two unique structural modifications in the unit cell. Although monoclinic 1 generally resembles the two molecules of triclinic 1, differences in the bond angles of up to 4.3' for triclinic molecule 2 and 7.2' for triclinic molecule 1 are found. A 1:l doublet was observed for the methyl carbons of 1 in the solid-state NMR spectrum of the monoclinic crystals, as expected from the symmetry found by X-ray." (9) Many examples are included in ref 6. More recent examples are given in ref 5 and in: Molloy, K. C.; Hossain, M. B.; van der Helm, D.; Zuckerman, J. J.; Mullins, F. P. Inorg. Chem. 1981,20,2172. Dahrnieks, D.; Hoskins, B. F.; Tiekink, E. R. T.; Winter, G. Inorg. Chim. Acta 1984, 85, 215.
(10) Waller, I.; Halder, T.; Schwarz, W.; Weidlein, J. J. Organornet. Chem. 1982,232, 99. (11) Lockhart, T. P.; Manders, W. F. Inorg. Chem. 1986, 25, 583.
Organometallics, Vol. 6, No. 12, 1987 2473
Analyses of Three Me2Sn(chelate)2Compounds
Sn-011 Sn-012 Sn-021 Sn-022 Sn-C1 Sn-C2 011-Cll 012-C 17
011-Sn-0 12 011-Sn-021 011-Sn-022 011-Sn-C 1 011-Sn-C2 012-Sn-021 012-Sn-022 012-Sn-C 1 012-Sn-C2 021-Sn-022 021-Sn-C1 021-Sn-C2 022-Sn-C1 022-Sn-C2
Table 111. Selected Bond Distances (A) and Bond Angles 2.159 (7) 021-c21 1.30 (1) 2.193 (8) 022-C27 1.28 (1) 2.140 (7) c11-c12 1.39 (2) 2.176 (7) C11-Cl7 1.47 (1) 2.14 (1) C12-Cl3 1.36 (2) 2.13 (1) C13-Cl4 1.40 (3) 1.30 (1) C 14-C 15 1.39 (2) 1.27 (1) C 15-C16 1.34 (2) 72.5 (3) 154.3 (3) 89.5 (3) 102.1 (4) 91.0 (4) 85.1 (3) 78.0 (3) 90.8 (4) 157.6 (5) 73.2 (3) 90.6 (4) 106.5 (5) 160.9 (4) 87.0 (4)
C 1-Sn-C 2 Sn-Oll-Cll Sn-012-Cl7 Sn-021-C21 Sn-022-C27 011-Cll-c12 011-Cll-C17 c12-Cll-c17 Cll-Cl2-Cl3 C12-Cl3-Cl4 c 13-c 14-c15 C14-Cl5-Cl6 C15-C 16-C 17 012-C17-Cll
107.9 (6) 118.7 (6) 117.5 (6) 118.3 (6) 117.3 (6) 119.1 (9) 114.5 (8) 126.4 (9) 131 (1) 131 (1) 125 (1) 132 (1) 131 (1) 116.2 (9)
(deg) for 1" C16-Cl7 c21-c22 C21-C27 C22-C23 C23-C24 C24-C25 C25-C26 C26-C27 012-Cl7-Cl6 Cll-C 17-C 16 021-c21-c22 021-C21-C27 c22-c21-c27 c21-c22-c23 c22-c23-c24 c23-c24-c25 C24-C25-C26 C25-C26-C27 022-C27-C21 022-C27-C26 C21-C27-C26
1.43 (1) 1.38 (2) 1.46 (1) 1.39 (2) 1.35 (1) 1.40 (2) 1.36 (2) 1.39 (1) 119.8 (9) 123.9 (9) 119.4 (8) 115.0 (9) 125.8 (9) 130.9 (9) 130 (1) 128 (2) 129 (1) 133 (1) 115.9 (8) 118.8 (9) 125.4 (9)
Numbers in parentheses are estimated standard deviations in the least significant digits.
Table IV. atom Snl Sn2 0 01 02 03 04 05 06 07 08 013 018 023 028 033 038 043 048 C
c1 c2 c3 c4
Positional Parameters and Their Estimated Standard Deviations of Non-Hydrogen Atoms in MezSn(kojate)z( 2 ) O X Y z B, A2 atom X Y z B , A2 0.40160 (4) 0.15183 (2) 0.42967 (3) 3.341 (8) c11 0.1808 (6) 0.2021 (2) 0.5045 (4) 3.4 (1) 0.32154 (2) 0.36539 (3) c12 4.2 (1) 0.54669 (4) 3.024 (8) 0.0619 (6) 0.2079 (2) 0.5293 (5) 11.1(2)* 0.0696 (3) 0.4679 (6) C14 0.0567 (8) 0.0750 (5) 0.2982 (2) 3.4 (1) 0.5260 (5) 0.1564 (2) 0.4982 (3) C15 3.94 (9) 0.2357 (4) 0.1921 (5) 3.2 (1) 0.2962 (2) 0.4977 (4) 0.4567 (3) 0.2431 (2) 3.52 (9) 0.3607 (4) C16 0.2512 (5) 0.2481 (2) 0.4837 (4) 3.1 (1) C17 0.4350 (3) 0.0001 (6) 0.0734 (2) 0.3458 (3) 4.33 (9) 0.3480 (4) 4.8 (2) 0.5432 (6) c21 0.3550 (4) 0.4069 (6) 0.1030 (2) 6.2 (1) 0.5520 (4) 0.0392 (2) 0.3862 (5) 3.3 (1) 0.3200 (2) 0.7154 (4) 3.93 (9) c22 0.3002 (3) 0.3694 (6) -0.0106 (2) 3.9 (1) 0.3705 (5) 0.2331 (2) 3.79 (9) C24 0.3431 (3) 0.5403 (6) 0.5923 (4) -0.0299 (2) 0.2857 (5) 3.6 (1) 0.3426 (3) 0.4021 (2) 0.0189 (2) 3.79 (9) C25 0.5851 (6) 0.5818 (4) 3.9 (1) 0.2963 (5) 0.3717 (2) 5.0 (1) C26 0.4424 (4) 0.5196 (6) 0.3977 (4) 0.0560 (2) 0.3454 (5) 3.9 (1) 4.4 (1) 0.2554 (2) 0.5416 (3) C27 0.5981 (7) 0.0082 (4) -0.0740 (3) 5.2 (2) 0.2358 (6) 6.0 (1) 0.2739 (2) 0.3896 (2) C31 0.5374 (4) 0.7660 (6) 0.0782 (4) 3.1 (1) 0.2873 (4) -0.0452 (2) 4.2 (1) C32 0.3204 (3) 0.4344 (4) 0.2679 (2) 0.8804 (6) 3.8 (1) 0.2542 (5) -0.0545 (2) 5.4 (1) 0.1777 (2) c34 0.1795 (4) 0.8697 (6) 0.6899 (5) 3.7 (1) 0.2619 (5) 0.2202 (2) 0.2402 (3) 0.9322 (4) 4.17 (9) 0.1797 (2) c35 0.7565 (5) 3.3 (1) 0.2970 (5) 0.8877 (5) 0.0839 (2) 0.2278 (2) 5.5 (1) C36 0.2779 (4) 0.6988 (5) 3.0 (1) 0.3112 (4) 0.5207 (2) 0.3561 (3) 3.78 (9) 0.1289 (3) 0.3980 (4) c37 0.9382 (7) 0.2395 (6) 5.2 (2) 5.0 (1) 0.1139 (4) 0.5303 (2) C41 0.4702 (4) 0.4927 (6) 0.4361 (2) 0.3603 (5) 3.3 (1) 10.6 (3)* 0.040 (1) 0.0618 (5) C42 0.569 (1) 0.4861 (2) 0.4906 (6) 3.6 (1) 0.3333 (5) 0.3078 (7) 0.2741 (5) 4.9 (2) 0.1697 (3) c44 0.3080 (6) 0.5045 (2) 0.4063 (4) 3.2 (1) 4.8 (2) 0.5691 (7) 0.5569 (6) 0.1616 (3) 0.4549 (2) 3.6 (1) c45 0.4358 (5) 0.3013 (6) 4.2 (1) 0.4183 (2) 0.6402 (7) 0.5234 (5) 0.3080 (3) C46 0.3935 (6) 3.5 (1) 0.4150 (5) 4.7 (2) 0.5474 (2) 0.3775 (7) 0.2410 (6) 0.3127 (3) c47 0.2169 (6) 4.2 (1) 0.4239 (5)
a Numbers in parentheses are estimated standard deviations in the least significant digits. Anisotropically refined atoms are given in the form of the isotropic equivalent displacement parameter defined as (4/3 [a2B(l,l) + b %(2,2) + c28(3,3) + ab(cos y)B(1,2) + ac(cos P)B(1,3) + bc(cos (u)B(2,3)].
Structure of MezSn(kojate)2.MeOH(2). The published7J2values of llJl (748 Hz) and l2Jl (83.3 Hz) for 2 lead to conflicting predictions of fMe-Sn-Me (143' and 135', respectively). We confirmed the solution lI9Sn and 13C data (Table I) but have found that the solid-state llJl value is considerably larger [905 Hz (average); estimated fMeSn-Me = 157'1. An X-ray structure determination carried out for 2 (Figures 2 and 3; Tables IV and V) revealed the presence of two unique molecules of 2 and two molecules of the crystallization solvent, MeOH, in the unit cell. The two molecules adopt the skew trapezoidal-bipyramida1I3 configuration that is relatively common for organotin(1V) compounds6and have fMe-Sn-Me values of 147.9 (3)O and 148.5 (3)O. On the basis of the difference between fMe' and I2J1values of 2, Sn-Me predicted from solution 14 (12) Otera, J.; Kawasaki, Y.; Tanaka, T. Inorg. Chem. Acta 1967, 1,
294.
(13) Kepert, D. L.
J. Organornet. Chern. 1976, 107, 49.
eq 1was predicted to fail for this compound; although the solid-state IIJl value is considerably larger than the solution value (indicating a difference in the solid-state and solution structures), this compound was indeed observed to fail the NMR structure correlation. The chelating ligands are nearly coplanar [the largest deviation from the SnlOl plane is 0.031 A (for Snl); from the Sn20, plane, 0.096 A (for 0511 but distorted significantly from square-planar geometry: cis 0-Sn-0 angles are from 72.5 (1)' to 136.5 ( 2 ) O for Snl and from 71.4 (1)O to 137.6 (1)' for Sn2; trans 0-Sn-0 angles are 150.8 (2)" (average) for S n l and 149.6 (6)O (average) for Sn2. Each kojate ligand bonds unsymmetrically to tin, one Sn-0 bond 0.28 A shorter, on average, than the longer Sn-0 bond. Evidence for hydrogen bonding in the crystal lattice comes from the relatively short intermolecular D(0-0) distances between methanol and three kojate oxygen atoms: oxygens 01 and 0 3 (2.86 and 3.12 A, respectively) bonded to S n l and hydroxy 038 (2.70 A). There are also
2474 Organometallics, Vol. 6,No. 12, 1987 Snl-01 Snl-02 Snl-03 Snl-04 Snl-C1 Snl-C2 Sn2-05 Sn2-06 Sn2-07 Sn2-08 Sn2-C3 Sn2-C4
0-c
01-Cll 02-C16 03-C21 04-C26 05-C31 01-Snl-02 01-Snl-03 01-Snl-04 01-Snl-C1 Ol-Snl-C2 02-Snl-03 02-Snl-04 02-Snl-Cl 02-Snl-C2 03-Snl-04 03-Snl-C1 03-Snl-C2 04-Snl-C 1 04-Snl-C2 C1-Snl-C2 05-Sn2-06 05-Sn2-07 05-Sn2-08 05-Sn2-C3 O5-Sn2-C4 06-Sn2-07 06-Sn2-08 06-Sn2-C3 06-Sn2-C4 07-Sn2-08 07-Sn2-C3 07-Sn2-C4 08-Sn2-C3 OS-Sn2-C4 C3-Sn2-C4
Lockhart and Dauidson
Table V. Selected Bond Distances (A) and Bond Angles (dea) for 2" 2.110 (4) 06-C36 1.267 (7) C14-Cl7 07-C41 1.328 (7) 2.435 (4) C 15-C16 2.106 (4) 08-C46 1.254 (7) c21-c22 0 13-C12 1.370 (8) 2.378 (6) C21-C26 1.342 (7) 013-C14 2.094 (6) C24-C25 1.397 (8) 018-C17 2.107 (6) C24-C27 1.374 (8) 023-C22 2.106 (4) (225426 1.335 (9) 023-C24 2.365 (4) C31-C32 1.43 (1) 028-C27 2.145 (4) C31-C36 1.371 (8) 033-C32 c34-c35 2.404 (5) 1.335 (8) 033-C34 c34-c37 2.100 (6) 1.412 (9) C35-C36 2.094 (6) 038-C37 1.387 (7) C41-C42 043-C42 1.39 (2) 1.320 (7) 1.325 (8) C41-C46 043-C44 1.410 (9) 1.262 (7) c44-c45 048-C47 1.34 (1) c44-c47 C l l - c 12 1.321 (8) 1.257 (7) 1.450 (8) C45-C46 Cll-C16 1.327 (7) 1.341 (9) C14-C 15 72.5 (1) 78.2 (2) 150.9 (2) 100.1 (2) 104.0 (2) 150.6 (2) 136.5 (2) 82.8 (2) 84.5 (2) 72.7 (2) 100.5 (2) 104.9 (2) 84.6 (2) 84.6 (2) 147.9 (3) 74.1 (1) 77.3 (2) 148.0 (1) 100.0 (2) 106.7 (2) 151.1 (2) 137.6 (1) 84.5 (3) 87.1 (2) 71.4 (2) 104.3 (3) 97.6 (2) 81.9 (2) 84.1 (2) 148.5 (3)
Snl-0 1-C 11 Snl-02-C16 Snl-03-C21 Snl-04-C26 Sn2-05-C31 Sn2-06-C36 Sn2-07-C41 Sn2-08-C46 C12-013-C14 C22-023-C24 C32-033-C34 C42-043-C44 01-c11-c12 01-Cll-C16 C12-Cll-C16 013-Cl2-Cll 013-C14-C 15 013-C14-C 17 c 15-c14-c 17 C14-Cl5-Cl6 02-C 16-C 11 02-Cl6-Cl5 Cll-C 16-C15 018-C 17-C 14 03-C21-C22 03-C21-C26 C22-C21-C26 023-C22-C21 023-C24-C25 023-C24-C27
118.4 (4) 109.7 (3) 118.3 (4) 111.8 (4) 117.0 (4) 110.8 (3) 118.2 (4) 112.2 (4) 119.0 (5) 119.9 (5) 119.3 (6) 119.8 (5) 122.8 (6) 118.9 (5) 118.4 (5) 122.9 (6) 122.5 (5) 110.8 (5) 126.8 (6) 120.6 (5) 119.1 (5) 124.3 (5) 116.6 (5) 109.6 (5) 124.5 (6) 118.4 (6) 117.0 (6) 122.8 (6) 122.2 (6) 111.2 (5)
c25-c24-c27 C24-C25-C26 04-C26-C21 04-C26-C25 C21-C26-C25 028-C27-C24 05-C31-C32 05-C31-C36 C32-C31-C36 033-C32-C31 033-C34-C35 033-C34-C37 c35-c34-c37 C34-C35-C36 06-C36-C31 06-C36-C35 C31-C36-C35 03&C37-C34 07-C41-C42 07-C41-C46 C42-C41-C46 043-C42-C41 043-C44-C45 043-C44-C47 c45-c44-c47 C44-C45-C46 08-C46-C41 OS-C46-C45 C41-C46-C45 048-C47-C44
1.497 (9) 1.415 (8) 1.343 (8) 1.452 (9) 1.338 (9) 1.51 (1) 1.411 (9) 1.353 (9) 1.447 (8) 1.349 (9) 1.51 (1) 1.408 (8) 1.338 (8) 1.454 (9) 1.344 (8) 1.504 (9) 1.409 (9) 126.7 (6) 119.9 (6) 117.8 (6) 123.9 (6) 118.2 (5) 109.8 (5) 122.8 (5) 119.3 (5) 118.1 (5) 122.6 (6) 122.5 (6) 112.2 (6) 125.3 (6) 120.2 (6) 118.5 (5) 124.1 (5) 117.4 (5) 113.0 (7) 124.2 (6) 117.9 (5) 117.9 (6) 122.2 (6) 122.3 (6) 112.0 (5) 125.6 (6) 120.1 (7) 117.8 (5) 124.6 (7) 117.7 (5) 113.0 (6)
" Numbers in parentheses are estimated standard deviations in the least significant digits. relatively short intermolecular 0-0contacts between pairs of kojate hydroxy oxygens 018 and 048 (2.84A), 028 and 048 (2.75A),and 0 7 and 028 (2.67A). The hydrogenbonding interactions of the kojate ligands and the presence of MeOH in the crystal lattice are presumed to be responsible for the large change in bonding at tin indicated by the solution and solid-state values of I'JI [the 160-Hz difference in 14 ' of 2 between solution and the solid state indicates a change of about 1 5 O in LMe-Sn-Me (assuming that the slope 10.7 Hz/deg in eq 1 applies)]. A relevant example of the profound influence that hydrogen bonding can have on methyltin(1V) structure is that of the cisdimethyl octahedral complex Me2Sn(N-hydroxyacetThe X-ray structure of the anhydrous compound gives LMe-Sn-Me = 109.1 (4)O;for the monohydrate, in which extensive hydrogen bonding between water and the N-hydroxyacetamide ligands occurs, LMeSn-Me = 156.8 (7)O. The 'H and 13C NMR spectra of 2 have no unusual features, but the broad '19Sn NMR resonance in DMSO-d6 (14) Harrison, P. G.; King, T. J.; Phillips, R. C. J. Chem. Soc., Dalton Trans. 1976, 2317.
(54Hz at half-height) and DMF-d, (70 Hz)suggests processes involving 2 in solution. Either association of solvent with tin or hydrogen bonding of the kojate ligand hydroxyl group to solvent or to another molecule of 2 (self-association) could give rise to the line broadening. Association of solvent with tin is considered the least likely because of the interruption of ligand chelation that would presumably be required. Several features of the solid-state 13C NMR spectrum merit comment. First, the presence of two unique molecules in the unit cell is clearly reflected in the NMR spectrum of the solid, where four methyl resonances are partially resolved (Figure 4). Methanol in the crystal lattice gives rise to a I3C singlet at 49.5 ppm. Interestingly, there appears to be a unique value of 1 9 1for each tinmethyl resonance (the limiting values of llJl observed, 860 f 20 and 930 f 20,are well outside the uncertainty of the measurement). Previous measurements of 14 ' for a large number of methyltin(1V) corn pound^^,^ were made at lower field strength (1.4 T), which would tend to obscure (or "average") small inequivalences. Only for a very few compounds, in which the methyls bonded to tin reside in markedly different chemical environments (e.g., an axial
Organometallics, Vol. 6, No. 12, 1987 2475
Analyses of Three Me$3n(chelate)2Compounds
t
1
1
24
1
1
1
~
1
21
1
1
1
l
1
1
18
1
1
1
1
1
15
1
1
1
1
1
1
1
12
1
1
~
l
9
~
l
~
1
1
l
6
1
1
1
1
1
1
3
1
1
1
1
1
1
1
1
0
PPM
Figure 4. High-resolution solid-state 13C NMR spectrum of polycrystalline Me2Sn(kojate)z(2) showin four resonances for methyl bonded to tin. Assignment of l1Iv117Sn satellites and magnitude of 11J(11gJ17Sn l3C)lOMare indicated in the spectrum. 11J(119Sn,'3C)I in the text Is obtained by multiplying the distance between the observed, fused '19Sn and ll'Sn satellites by 1.023. versus an equatorial methyl in a trigonal bipyramidal complex), were separate I'Jl values observed., A t higher field strengths such as that used here (7 T), such inequivalences may be observed more frequently. The structural source (and assignments) of the different llJl values are not readily apparent. An effort was made to obtain methanol-free crystals of 2 in the hope that such crystals would have the cis-dimethyl octahedral configuration suggested by the solution NMR data. Repeated recrystallization of 2 from a mixture of hot CH&N and DMSO gave well-formed crystals melting at 180-182 "C. Solution lH NMR of the crystals indicated a constant, approximately 1:4 molar ratio of MeOH to 2. The solid-state 13C NMR spectrum showed a 1:l doublet for methyls bonded to tin, indicating that a new crystalline modification of 2 had been formed. The llJl value (910 Hz) was essentially unchanged from the X-ray characterized modification, implying a very similar molecular structure. Sublimation was also investigated as a means for removing the methanol of crystallization. A low yield (10%) of white sublimate having a new, sharp melting point was obtained at 170 "C; it was unsuitable, however, for X-ray studies. Solid-state 13C NMR analysis of the sublimate indicated complete loss of MeOH; resolved resonances a t 5.1 and 8.7 ppm (ratio 2-3:l) were observed for the methyls bonded to tin. There was insufficient sample to measure 1'4. Structure of Me2Sn(picolinate)z(3). Because of the small solution zJ value reported15for 3 in CHBr, (77.6 Hz, estimated LMe-Sn-Me = 128'1, this compound seemed another possible candidate for the cis-dimethyl octahedral tin geometry. We found a somewhat larger value of I2JI in CHBr, (83 f 2 Hz), but poor solubility prevented our making 13Cand ll9Sn NMR measurements in this solvent. In DMSO-$, very large values of I'JI (1154 Hz) and I2Jl (117.4 Hz) and a large, negative l19Sn chemical shift (-451 ppm) were found. The solid-state llJl value (1155 f 20 Hz) was similar to that in DMSO. These data indicated that the solid-state and DMSO solution structures of 3 are markedly different from that in CHBr,. The llJl and I2Jl values in DMSO lead to conflicting predictions of LMeSn-Me of 181" and 200°, respectively; the latter exceeds the greatest possible angle by 20". The lack of X-ray structural studies on six-coordinated tin(1V) picolinates, and the manifold bonding possibilities (15) McGrady, M. M.; Tobias, R. S. J.Am. Chem. SOC. 1965,87,1909.
8
022
Figure 5. ORTEP plot showing three repeating units of polymeric (3) and the numbering scheme. MezSn(picolinate)2 Table VI. Positional Parameters and Their Estimated Standard Deviations of Non-Hydrogen Atoms in MezSn(picolinate)z( 3 ) O atom X Y z B, A2 Sn 0.17321 (3) 0.63649 (4) 0.25255 (3) 2.516 (7) 011 0.0439 (3) 0.4403 (4) 0.2577 (3) 3.27 (9) 012 0.0136 (3) 0.2256 (4) 0.3264 (3) 3.16 (8) 021 0.3575 (3) 0.6888 (5) 0.3061 (3) 4.1 (1) 022 0.5007 (3) 0.8490 (5) 0.3271 (4) 4.6 (1) N11 0.2715 (4) 0.4034 (5) 0.3394 (3) 3.0 (1) N21 0.2062 (3) 0.8842 (5) 0.1879 (3) 2.53 (9) C1 0.1664 (5) 0.7139 (7) 0.3922 (4) 3.9 (1) C2 0.5485 (7) 0.1653 (6) 0.1119 (4) 4.0 (1) C10 0.0766 (4) 0.3230 (6) 0.3067 (4) 2.6 (1) C11 0.2035 (4) 0.2924 (6) 0.3486 (4) 2.5 (1) C12 0.3857 (5) 0.3824 (7) 0.3792 (5) 3.8 (1) 0.2512 (8) C13 0.4330 (5) 0.4270 (6) 4.6 (2) C14 0.3631 (5) 0.1360 (7) 0.4342 (5) 3.9 (1) C15 0.2460 (5) 0.1563 (6) 0.3947 (4) 3.2 (1) C20 0.8151 (6) 0.4006 (4) 0.2899 (4) 3.2 (1) C21 0.3178 (4) 0.9209 (6) 0.2180 (4) 2.7 (1) C22 0.1310 (4) 0.9784 (6) 0.1257 (4) 3.0 (1) C23 0.1627 (5) 1.1116 (6) 0.0914 (4) 3.3 (1) C24 0.2771 (5) 1.1488 (6) 0.1236 (4) 3.4 (1) C25 0.3554 (4) 1.0537 (6) 0.1867 (4) 3.2 (1) Numbers in parentheses are estimated standard deviations in the least significant digits. Anisotropically refined atoms are given in the form of the isotropic equivalent displacement parameter defined as 4/3[a2B(l,l) b2B(2,2) c2B(,3,3)+ &(cos y)B(1,2) ac(cos @B(1,3) + bc(cos (u)B(2,3)].
+
+
+
of the picolinate group led us to determine the X-ray structure of 3 (ORTEP plot in Figure 5, positional parameters in Table VI, bond angles and distances in Table VII). As expected from the solid-state NMR data, a large LMe-Sn-Me, 174.5 (3)O, was found for 3. A surprising result is that 3 forms a linear coordination polymer in the solid-state, with the unusual dimethyltin(IV) coordination number of 7:16 Both picolinate ligands chelate to one tin, bonding through one carboxylate oxygen and the nitrogen atom; an additional intermolecular Sn-0 interaction between each tin and the second carboxylate oxygen (012) (16) Well-documented, seven-coordinate dimethyltin(1V) complexes are described in: (a) Naik, D. V.; Scheidt, W. R. Jnorg. Chem. 1973,12, 272. (b) Constable, E. C.; Khan, F. K.; Lewis, J.; Liptrot, M. C.; Raithby, P. R. J . Chem. Soc., Dalton Trans. 1985, 333. Less clearly established cases of seven-coordination (in compounds having one, or more, Sn-0 bonds > 2.99 A) appear in: (c) Valle, G.; Peruzzo, V.; Tagliavini, G.; Ganis, P. J. Organornet. Chem. 1984,276,325. (d) Faggiani, R.; Johnson, J. P.; Brown, I. D.; Birchall, T. Acta Crystallogr., Sect. E : Struct. Crystallogr. Cryst. Chen. 1978, B34, 3743.
2476 Organometallics, Vol. 6, No. 12, 1987
Sn-011 Sn-012 Sn-021 Sn-N11 Sn-N21 Sn-C1 Sn-C2 011-c10 012-c10 011-Sn-012 011-Sn-021 011-Sn-Nl1 011-Sn-N21 Oll-Sn-Cl 011-Sn-C2 0 12-Sn-02 1 012-Sn-N11 012-Sn-N21 012-Sn-C1 012-Sn-C2 021-Sn-N11 021-Sn-N21 021-Sn-C1 021-Sn-C2 N ll-Sn-N21 N11-Sn-C1
Lockhart and Davidson
Table VII. Selected Bond Distances 2.393 (4) 021-c20 2.340 (3) 022-c20 2.199 (4) N11-C11 2.507 (4) Nll-C12 2.477 (4) N21-C21 2.112 (7) N21-C22 c10-c 11 2.100 (7) 1.242 (7) Cll-C15 1.262 (7) C12-Cl3 72.4 (1) 140.8 (1) 66.2 (1) 149.4 (1) 88.3 (3) 86.5 (2) 146.7 (1) 138.6 (1) 77.5 (1) 89.0 (2) 87.8 (2) 74.6 (1) 69.8 (1) 88.9 (2) 96.3 (2) 143.7 (1) 89.2 (3)
N11-Sn-C2 N21-Sn-Cl N21-Sn-C2 C1-Sn-C2 Sn-Oll-ClO Sn-012-C10 Sn-021-C20 Sn-N11-Cl1 c21-c25-c24 Sn-N11-Cl2 Cll-Nll-ClZ Sn-N21-C21 Sn-N21-C22 C21-N21-C22 Oll-C10-012 Oll-C10-C11 012-c 10-c 11
(A)and Bond Angles (deg) for 3" 1.301 (7) 1.209 (6) 1.335 (8) 1.347 (7) 1.344 (6) 1.335 (6) 1.505 (7) 1.392 (7) 1.377 (9)
C13-Cl4 C14-C 15 c20-c21 C21-C25 C22-C23 C23-C24 C24-C25
90.5 (2) 96.6 (3) 87.1 (3) 174.5 (3) 122.6 (4) 135.8 (4) 124.5 (3) 116.4 (4) 119.5 (5) 125.8 (4) 117.8 (5) 112.6 (4) 129.5 (3) 117.8 (5) 126.5 (5) 118.0 ( 5 ) 115.6 (4)
N 11-C1 1-C10 N 1l-Cll-Cl5 ClO-C11-C15 Nll-Cl2-Cl3 c12-c13-c 14 CL3-Cl4-Cl5 c11-c 15-c 14 021-c20-022 021-c20-c21 022-c20-c21 N2 1-C21-C20 N21-C21-C25 c20-c21-c25 N21-C22-C23 c22-c23-c24 c23-c24-c25
1.38 (1) 1.378 (8) 1.502 (7) 1.399 (9) 1.389 (8) 1.375 (8) 1.364 (7)
116.1 (4) 122.7 (5) 121.3 (5) 122.2 (6) 119.9 (5) 118.6 (5) 118.8 (5) 124.4 (5) 115.8 (4) 120.0 (5) 117.0 (5) 121.7 (4) 121.3 (4) 123.3 (5) 118.5 (5) 119.3 (6)
Numbers in parentheses are estimated standard deviations in the least significant digits.
of one picolinate ligand of a neighboring molecule gives rise to the polymeric structure. It is striking that the seventh coordinated atom (012 of a neighboring molecule) in 3 is not held in the coordination sphere of tin as part of a bi- or tridentate ligand system (as is the case for the other unambiguously 7-coordinated dimethyltin(IV)slG). The overall configuration at tin is best described as pentagonal bipyramidal: tin and the bonded oxygen and nitrogen atoms are nearly coplanar and deviate only slightly from regular pentagonal geometry [range of angles LXSn-X = 66.2 (1)-77.5 (1)O, sum = 360.5 ( 5 ) O ; greatest deviation from the SnN203plane is 0.146 (5) A for N l l ] . Methyl groups occupy the apical positions. In spite of the slightly asymmetric disposition of the two methyl groups, only a single, narrow methyl resonance is observed in the solid-state 13C NMR spectrum. Cautionary notes have been sounded recently17 concerning the assignment of coordination numbers to organotin(1V) compounds solely on the basis of the apparent molecular configuration. However, the Sn-0 and Sn-N distances in the pentagonal plane of 3 are considerably shorter than the sum of the van der Waals radii18 (3.68 for Sn-0, 3.71 A for Sn-N): range of D(Sn-0) = 2.199 (4)-2.393 (4) A; D(Sn-N) = 2.477 (4) and 2.507 (4) A. The Sn-0 and Sn-N distances are well within the range considered to be bonding,6 though the Sn-N distances are somewhat longer than average.lg A molecular weight determination for 3 in CHBr, solution15 and comparison of the solution and solid-state IR spectra in CHClZO indicate that the polymeric solid-state structure of 3 does not persist in solution. Similar depolymerization upon dissolution is well-known for other organotin(1V) coordination polymers.21 The small I2Jl of 3 ~~~
(17) Baxter, J. L.; Holt, E. M.; Zuckerman, J. J. Organometallics 1985, 4, 255. Ganis, P.; Valle, G.; Furlani, D.; Tagliavini, G. J. Organomet. Chem. 1986, 302, 165. (18) Bondi, A. J. Phys. Chem. 1964, 68, 441. (19) Comparable or longer bonding Sn-N distances have been aasigned in ref 16a and in: Swisher, R. G.; Holmes, R. R. Organometallics 1984, 3, 365. van Koten, G.; Noltes, J. G. J. Organomet. Chem. 1976,118, 183. Jastrzebski, J. T. B. H.; van Koten, G.; Knaap, C. T.; Schreurs, A. M. M.; Kroon, J.; Spek, A. L. Organometallics 1986,5, 1551. (20) Howard, W. F.; Nelson, W. H. J. Mol. Struct. 1979, 53, 165.
in CHBr3is consistent with the presence of five-membered chelate rings as shown for 3A. Four-membered chelate
3A
38
3c
3n
rings formed through bidentate carboxylate groups (as in 3B) are known for MezSn(acetate)z,5c*22 however, and could also give rise to a comparable 12qvalue. The large I1qand l2J1 values for 3 in DMSO solution indicate an approximately linear Me-Sn-Me angle. Because all characterized examples of trans-dimethyl octahedral complexes involve either monodentate Me2SnX2L2ligand systems (e.g., X = C1, L = or the six-membered chelate rings of MezSn(acac)z,24 neither 3A nor 3B are likely structures for 3 in DMSO. Alternate structures better able to accommodate the large LMe-Sn-Me angle are seven-coordinate 3C and six-coordinate 3D, in both of which a molecule of DMSO solvent is present in the coordination sphere of (21) A general discussion is given in: Davies, A. G.; Smith, P. J. In Comprehensiue Organometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford, 1982; Vol. 2. (22) Lockhart, T. P.; Calabrese, J. C., Organometallics, in press. (23) Aslanov, L. A.; Ionov, V. M.; Attiya, W. M.; Permin, A. B. J. Struct. Chem. 1978,19,166. Aslanov, L. A.; Ionov, V. M.; Attiya, W. M.; Permin, A. B.; Petrosyan, V. S. J. Organomet. Chem. 1978,144,39. Blom, E. A.; Penfold, B. R.; Robinson, W. T. J. Chem. SOC.A 1969,913. Randaccio, L. J. Organomet. Chem. 1973,55, C58. Isaacs, N. W.; Kennard, C. H. L. J. Chem. SOC. A 1970,1257. Schlemper, E. 0.; Hamilton, W. C. Inorg. Chem. 1966,5, 995. Davies, A. G.; Milledge, H. J.; Puxley, D. C.; Smith, P. J. J. Chem. SOC. A 1970, 2862. Aslanov, L. A.; Ionov, V. M.; Attiya, W. M.; Permin, A. B.; Petrosyan, V. S. J. Struct. Chem. 1977,18, 876. Allen, F. H.; Lerbscher, J. A,; Trotter, J. J. Chem. SOC.A 1971,2507. Smart, L. E.; Webster, M. J. Chem. SOC.,Dalton Trans. 1976, 1924. (24) Miller, G. A.; Schlemper, E. 0. Inorg. Chem. 1973, 12, 677.
Analyses of Three MezSn(chelate)zCompounds tinez The extremely broad l19Sn resonance for 3 in DMSO (ca. 250 Hz at half-height) is consistent with the interaction of solvent with tin as postulated in these structures. Two arguments strongly favor seven-coordinate structure 3C: (1) The similarity of the solid-state and DMSO solution 14 ' values is consistent with a minimal change in structure (Le., retention of seven-coordination). (2) l19Sn chemical shifts are generally very sensitive to coordination number, higher coordinate complexes having larger negative shifts.% The l19Sn chemical shift of 3, -451 ppm, is 85 ppm upfield of that of trans-dimethyl, six-coordinate Me2Sn(acac)2 (-365 and is the largest negative '19Sn chemical shift yet reported for a dimethyltin(1V) complex. Somewhat less forcefully, it can be argued that the solvent-induced disruption of picolinate chelation required in 3D is unlikely, although one example of a monodentate picolinate ligand in a five-coordinate tin complex (the nitrogen is involved in hydrogen bonding to a molecule of H20) has been reported.27 Because of the evidence that 3 adopts a dramatically different structure in the nonpolar solvent CHBr3, attempts were made to isolate other structural modifications. However, only powdery products could be isolated from CHBr, solution, and sublimation gave a product with a solid-state NMR spectrum identical with that of the crystalline modification already characterized.
Conclusions Results described in this paper support the comparison of Me-Sn-Me angles estimated from I'Jl and I2JI,measured in the same solvent, in order to ascertain whether eq 1 and 2 are likely to provide reliable LMe-Sn-Me estimates for a given dimethyltin(1V)compound. Previously, eq 1 had been found to lead to significant overestimates of LMe-Sn-Me only for cis-dimethyl octahedral tin(1V) compounds such as 1. The inaccurate LMe-Sn-Me estimated for 2, which has an intermediate LMe-Sn-Me, however, indicates that the deviation does not depend strictly on the unusual cis-dimethyl configuration. Notably, 2 and all three of the known cis-dimethyl octahedral tin(1V) compounds (including l), which have estimated Me-Sn-Me angles >go off the correlation, have fivemembered chelate rings. No Me2Sn(chelate)2compounds with five-membered chelate rings have yet been found that obey closely both eq 1 and 2, but dimethyltin(1V) compounds with four- and six-membered chelate rings are all well-behaved. The source of the influence of the fivemembered chelate rings on the NMR properties of these compounds is not clear. ll9Sn chemical shifts (which reflect the electron density on tin) of several Me2Sn(chelate), compounds bearing five-membered chelate rings have been found: in general, to be considerably smaller than those bearing four- and six-membered chelate rings; this supports the hypothesis of an unusual electronic effect in the fivemembered ring chelate compounds studied thus far. In terms of "bite" size, these ligands are intermediate between those which form four- and six-membered chelate rings and are not distinguishable in terms of steric bulk. It is our hope that these results, along with data for the well-be(25) The solution structures of compounds R2Sn(picolinate)2,where R = Me, Et, n-octyl, cyclohexyl, and t-Bu have also been considered in other studies: see ref 21, Crowe, A. J.; Hill, R.; Smith, P. J.; Brooks, J. S.; Formstone, R. J. Organornet. Chern. 1981, 204, 47. Dietzel, S.; Jurkschat, K.; Tzschach, A.; Zschunke, A. 2.Anorg. Allg. Chern. 1986, 537, 163.
Organometallics, Vol. 6, No. 12, 1987 2477 haved dimethyltin(1V) compounds, will stimulate the application of theory to the bonding of organotin compounds and to spin-coupling interactions involving heavy atoms such as tin.
Experimental Section MezSn(tropolonate)z(1). Tropolone (Aldrich) and MezSnClZ (Alfa) were used in the procedure given by Komura.' Well-formed, amber-colored hexagonal rods of 1 were obtained from hot ethanol solution; mp 185-186 "C (lit. mp 181-183 "C). Me2Sn(kojate)z(2). Kojic acid (Aldrich) and MeZSnCl2were used. The procedure of Otera12was followed, except that we found that 2 equiv of aqueous ammonia were necessary for complete conversion. The amber-colored product was isolated in 85% yield and identified by melting point (decomposition) (lit. 194-195.5 "C vs 185-198 "C) "C) and elemental analysis. Crystals suitable for X-ray were obtained from methanol solution. The product was insoluble (CO.1 g/50 mL) in hot CHC13, benzene, tetrahydrofuran, and acetonitrile. Compound 2 sublimed over several days when heated t o 170 "C under vacuum (0.01 torr). At a temperature of 100-120 "C the sample "popped" on the floor of the sublimation apparatus, owing to loss of methanol in the crystal lattice. From 1 g of crystalline 2, only 0.17 g of a snow-white, powdery sublimate was isolated; mp 148.5-150 "C. MezSn(picolinate)z(3). Prepared from dimethyltin oxide (Alfa) and picolinic acid (Aldrich) in 55% yield.15 Long, flat barlike, colorless crystals [mp 257-259 "C dec (lit. mp 267-268 "C)] suitable for X-ray were obtained from hot methanol solution to which some benzene had been added. The product was insufficiently soluble in CHzCl2,CHCl,, dimethylformamide, tetrahydrofuran, or acetone to permit 13C NMR studies to be carried out. An attempt was made to obtain crystals of 3 from hot CHBr3 solution, but only a low recovery of a tan powder unsuited for X-ray was obtained. A 70% yield of a white sublimate (powder) was obtained when 3 was heated for about 1.5 days a t 240 "C and 0.01 torr. The composition of the sublimate was confirmed by solid-state 13C NMR and elemental analysis. NMR Spectroscopy. Solution NMR spectra were recorded on a General Electric NT-300 a t 75 MHz for 13C and 11.209 MHz for l19Sn. The external reference (0 ppm) used for 13C spectra was Me4%; Me4Sn was used for '19Sn. l19Sn spectra for 1 and 2 were recorded by using an inverse gated decoupling to suppress the nuclear Overhauser effect. The l19Sn spectrum of 3 was obtained with broad-band proton decoupling. Solid-state 13C NMR (MAS) spectra were obtained on both a General Electric S-100 spectrometer (25.2 MHz) and a Bruker CXP-300 spectrometer (75.5 MHz). Dry nitrogen gas was used to drive MAS rates of 2.5 k H z (S-100) to 4.5 kHz (CXP-300). The Hartmann-Hahn matching condition for cross-polarization (CP) was calibrated by using adamantane, and both CP ( 5 ms) and decoupling (40 ms) were performed at the same proton-decoupling amplitude (50 kHz, S-100, or 71 kHz, CXP-300). A 4-9 recycle delay was used, and spectra were obtained after 2OCC-16000 scans. Chemical shifta are reported relative to MelSi by using an external sample of adamantane as reference. The 13C of methyls bonded to tin gave rise to small or unobservable spinning sidebands reflecting their small chemical shift anisotropy. Crystal Structure Determinations a n d Refinements. Crystal data and data collection parameters are given in Table VIII. Details of the X-ray structure solution (carried out on an Enraf-Nonius CAD4 computer-controlled K axis diffractometer equipped with a graphite crystal, incident beam monochromator, at Oneida Research Services, Inc.) are described below. The structures were solved by direct methods. For all three structures, hydrogen atoms were added to the structure factor calculations a t their calculated positions, but their positions were not refined. The structures were refined in full-matrix least squares where the function minimized was Cw(lF,,I - IFJ). Unit weights were used for all observed reflections. Neutral atom scattering factors were taken from Cromer and Anomalous dispersion effects were included in Fc;30the values for f 'and f "were those
(26) Smith, P. J.; Tupciauskas, A. P. Annu. Rep. N M R Spectrosc.
19711. 8. 291. --.-I - 7
(27)Okra, J. J . Organornet. Chern. 1981, 221, 57. (28) Gabe, E. J.; Lee, F. L.; Khoo, L. E.; Smith, F. E. Inorg. Chern. Acta 1986, 112, 41.
(29) Cromer, D. T.; Waber, J. T. International Tables for X - R a y Crystallography; Kynoch Birmingham, England, 1974;Vol. IV; Table 2.2B.
2478 Organometallics, Vol. 6, No. 12, 1987
Lockhart and Davidson
Table VIII. Crystal Data and Data Collection Parameters 1 2
3
Crystal Data empirical formula fw, g/mol crystal dimens, mm peak width at half-height, deg radiatn temp, "C monoclinic space group a, A
b, A e, A a, deg P, deg 7,deg
v, A3
Z
D(calcd), g/cm3 abs coeff, cm-' attenuator, factor takeoff angle, deg detector aperture, mm horizontal vertical scan type scan rate, deg/min, in to scan width max 28, deg no. of reflctn measd total unique correctns: Lorenzt-polarization linear decay, on I reflectn averaging, agreement of I , % empirical absorption, on I least-squares weight anomalous dispersion reflctns included parameters refined unweighted agreement factor weighted agreement factor esd of observn of unit weight high peak infinal diff map, e/A3
C16H16Sn04
C29H36Sn2017
390.99 0.14 X 0.42 X 0.42 0.30 Cu K a (A = 1.541 84A) 23 (1) w c 10.732 (2) 14.181 (2) 10.574 (2) 90 98.18 (1) 90 1592.9 (9) 4 1.63 131.7
893.98 0.26 X 0.28 X 0.34 0.29 Mo Kcu (A = 0.71073A) 23 ( 1 ) 10.253 (1) 25.834 (2) 13.151 (2) 90 103.82 (1) 90 3383 (1) 4 1.76 15.5
Intensity Measurements Zr, 19.4 Ni, 21.1 2.8 2.8
23 (1) m1/c 12.409 (1) 8.922 (6) 14.071 (3) 90 110.06 (1) 90 1463 (1) 4 1.78 17.7 Zr, 19.4 2.8
2.0-3.5 4.0 W-8 2-5 0.9 + 0.140 tan R 114.0
2.0-2.4 4.0
2.0-2.4 4.0
w-R
w-8
2-5 0.8 + 0.140 tan R 46.0
2-5 1.0 + 0.140 tan 0 46.5
2387 2095
5128 4632
2349 2061
0.950-1.029 3.0 0.29-0.99
0.944-1.031 1.5
0.979-1.049
Structure Solution and Refinement 4F,2/aZ(F,2) 4F,2/ u2(F,2) all non-hydrogen atoms 1905 with F? > 3.0a(FO2) 4362 with F? 190 423 0.039 0.059 0.039 0.062 2.71 2.63 1.19 (9) 1.86 (13)
of Cromere31 All calculations were performed on a VAX-11/750 computer using SDP-PLUS.32 Unweighted and weighted agreement factors are defined as R = CllF,,l- IFcll/CIFoland R, = (x:w(lFol- IFc1)2/C~F,2)1/2. Plots of Zw(lFol - lFc1)2versus IF& reflection order in data collection, (sin 6)/X, and various classes of indices showed no unusual trends for any of the three compounds. For all three structures, the largest residuals were found near tin. Details of the individual structure solutions are given in Table VI11 or below. Structure Solution of 1. A total of two phase sets were produced for 1 by using 257 reflections (minimum E of 1.59)and 6173 relationships. The highest peak in the final difference Fourier had a height of 1.86 e/A3 with a n estimated error based on hFoz of 0.14. Structure Solution of 2. Using 367 reflections (minimum E of 1.78) and 9335 relationships, a total of 32 phase sets were produced. The hydroxy hydrogen atoms and those of the methanol of solvation were not included in the refinement. The largest parameter shift was 0.04 times its estimated standard deviation in the final cycle of refinement. The highest peak in (30) Ibers, J. A.; Hamilton, W. C. Acta Crystallogr. 1964, 17,781. (31) Reference 29, Table 2.3.1. (32) Frenz, B. A. In Computing in Crystallography; Schenk, H., 01-
thof-Hazelkamp, R., vanKonigsveld, H., Bassi, G. C., Eds.; Delft Univ-
ersity Press: Delft, Holland, 1978; pp 64-71.
mln
C14H14SnN204 392.97 0.23 X 0.25 X 0.58 0.34
1.1 0.88-1.00
> Z.Ou(F2)
1951 with F: 190 0.030 0.036 1.80 0.87 (9)
> 3.Ou(F:)
the final difference Fourier had a height of 1.19 e/A3 with an estimated error based on A F of 0.10. Structure Solution of 3. A total of 16 phase sets were produced by using 257 reflections (minimum E of 1.55) and 6397 relationships. In the final cycle of refinement the largest parameter shift was 0.01 times its estimated standard deviation. The highest peak in the final difference Fourier had a height of 0.897 e/A3 with an estimated error based on AF of 0.09.
Acknowledgment. X - r a y structure d e t e r m i n a t i o n s were carried out b y R. R. W h i t t l e (Oneida Research Services). The expert assistance of R. D. Farlee and R. F . C a r v e r (Du P o n t ) in o b t a i n i n g solid-state NMR data is gratefully acknowledged.
Registry No. 1, 21844-38-2; 2, 110508-55-9; 2.1/2MeOH, 110508-57-1; 3,110508-56-0; MezSnClz,753-73-1; llgSn, 14314-35-3; tropolone, 533-75-5; kojic acid, 501-30-4; dimethyltin oxide, 2273-45-2; picolnic acid, 98-98-6. Supplementary Material Available: Tables of positional parameters, root-mean-square amplitudes, bond distances, bond angles, torsional angles, anisotropic thermal parameters, and calculated equations of planes for 1,2, and 3 (41 pages); listings of structure factor amplitudes for 1,2, and 3 (21 pages). Ordering information is given on any current masthead page.
