445 nonequivalent Cu-N distances below 280'K. Preliminary structural data for the orthorhombic phase indicate that the CuN6 environment is compressed tetragonal with Cu-N distances of 2.07, 2.13, and 2.15 A.II The corresponding nickel(I1) compound, K2PbNi(N02)6, is cubic over the range of temperatures measured (1 30-295'K)." Thus, the changes in M2M'Cu(N02)6 structures can be attributed to the Jahn-Teller effect. Work is in progress which should provide precise structural data for K2PbCu(N02)6 below 280'K and for other crystals containing and Ni(N02)64- clusters with various counterions.
Acknowledgment. Support of this research by the National Science Foundation (GP-38022X) is gratefully acknowledged. References and Notes Figure 1. Hexanitrocuprate(I1) anion showing atom numbering, thermal motion, and crystal axes. (Drawing produced b y the computer program ORTEP; C . K . Johnson, O a k Ridge National Laboratory Report ORNL-3794, Oak Ridge. Tenn., 1965.)
prate( 11),I barium hexafluorocuprate(II),2 and bis(diethylenetriamine)copper(11) nitrate.3 However, these are of limited value for studying Jahn-Teller effects since the Cu(I1) ligands are not e q ~ i v a l e n t . ~ In the fluoride complexes, K ~ C U and F ~ (BaF)2CuF4, the long Cu-F distances are for four fluoride ions which bridge two Cu(I1) ions while the short Cu-F distances are for nonbridging fluoride ions. The corresponding Ni(I1) compounds K2NiF45 and (BaF)2NiF4* also show four long and two short Ni-F distances and, since six-coordinate Ni(I1) is not a Jahn-Teller ion, the distortions observed in the Cu(I1) complexes cannot be attributed to Jahn-Teller effects alone. The bis(diethylenetriamine)copper(II) nitrate structure is not a good example of Jahn-Teller distortion since the ligands are tridentate and the Cu(")-N distances are determined in part by constraints imposed by the ligand geometry. The four long Cu-N bonds range from 2.17 (1) to 2.26 ( 2 ) A, the two short Cu-N bonds average 2.01 A, and all intraligand N-Cu-N angles are approximately 80'. The two short Cu-N distances correspond to the secondary amine nitrogen atoms and the four long bonds to primary amine atoms,j thus the ligands are again not equivalent. The corresponding Ni( 11) compound shows a similar geometry with two short Ni-N (secondary) bonds and four long Ni-N (primary) bonds6 The same authors report the bis[di-(3-aminopropyl)amine]nickel(II) compound6 which has two long and four short Ni-N bonds. They conclude that the Ni-N distances are strongly influenced by the ligand geometry. In 1939 Van Vleck' stated, "It would be interesting if a physical case could be found where the cluster X.6H20 resonates through a variety of Jahn-Teller configurations, as then we would have a nice example of a characteristic quantum mechanical effect." W e have sufficient evidence now to indicate that the cluster C U ( N O ~ ) is ~ ~such - an example since the presence or absence of a static distortion as well as the type of distortion depends on the counterion and on the temperature. For example, both K2BaCu(N02)68 and KrCaCu(NO&9 crystallize in the same space group as Rb2PbCu(NO&, but the CuN6 environment is elongated tetragonal rather than compressed tetragonal in the presence of the K+ counterion. A further example is provided by the observation that K2PbCu(N02)6 undergoes a reversible phase change from the cubic space group Fm 3 with equal Cu-N distancesI0 to the orthorhombic space group F m m m with
(1)K. Knox. J. Chem. Phys., 30, 991 (1959). (2)H. G.von Schnering, 2.Anorg. Allg. Chem., 353, 13 (1967). (3)F. S.Stephens, J. Chem. SOC.A, 883 (1969). (4)P. T. Miller, P. G. Lenhert, and M. D. Joesten, horg. Chem., 12, 218 (1973). (5)D. Balz, Naturwissenschaften, 40,241 (1953). (6)S.Biagini and M. Cannas, J. Chem. SOC.A, 2398 (1970). ( 7 ) J. H. Van Vleck, J. Chem. Phys., 7 , 61 (1939). (8)S. Takagi. M. D. Joesten, and P. G Lenhert, accepted for publication, Acta Crystallogr.
(9)S.Takagi. P. G. Lenhert. and M. D. Joesten. J. Amer. Chem. SOC., 96, 6606 (1974). (IO)D. L. Cullen and E. C. Lingafelter. inorg. Chem., IO, 1264 (1971). (11) S.Takagi. M. D. Joesten, and P. G. Lenhert, unpublished results. (12)(a) Department of Chemistry: (b) Department of Physics.
Shozo Takagi,Iza Melvin D. Joesten,*lznP. Calen Lenhert*lzb Departments of Chemistry and Physics, Vanderbilt University Nashville, Tennessee, 38235 Received October 7. 1974
Effect of Micelles on the Rate and Stereochemistry of Solvolytic Displacement Reactions Sir:
We wish to report the synthesis of a series of unusually reactive water soluble sulfonates (Ia-c) which has allowed us to study, for the first time, the effect of micelle formation' on the rate and stereochemistry of simple solvolytic displacement reactions. W e have found that cationic micelles show little or no effect on the displacement reaction; in contrast, micelles formed from anionic surfactants bind Ia-c strongly, retard their rate of aqueous solvolysis by at least two orders of magnitude, and change the observed stereochemistry of displacement in Ib from 100% net inversion to 56% net inversion.2
' '
CjH,,--C--C--OSO,
O k C H ) ) , CF SO -
I 1 H H
Ia, R, = CHI; R? = H Ib, R, = H; RL= CH
IC, R,
=
-
R2 H
W e chose I as the system for study3 because these compounds are water soluble as well as structurally similar to the water insoluble sulfonates more traditionally used in solvolytic s t ~ d i e sAlso, . ~ sulfonates of structure I are surface active5 and thus self-miceliize and should bind well to micelles composed of other surfactants. The nonmicellar solvolytic behavior of sulfonates I in water can be summarized as follows: ( 1 ) they exhibit conveCommunications to the Editor
446 Rates of Solvolysis of Alkyl p-Trimethylammonium Beiizenesulfonate Esters in Water with and without Added Surfactants
Table 11. Dependence of Stereochemistry of Solvolytic Displacement of Ib on Concentration of Ib and Added Sodium Lauryl Sulfate (SLS) in Water at 25'
Table I.
Sub- Concna strate X loJ la
Ib
IC
Additive (cmc X Concn Temp k(sec-1) lo3)
X
lo3
2.75 8.25 1.27 CTAB(0.7) 1 . 2 7 3.84 SLS(8.3) 17 0.21 4 . 2 SLS(8.3) 17 1.0
x
('C)
30 30 30 30 25 25 40
tl
105
(min)
3.9c 3.9c 3.9c
300
High [SLS]; low-to-moderate [Ibl
SLSX 102
2 2 2 1
0.7 50 40
Molar units. * Determined by titration. Determined by Fourier
transform nmr.
[Ibl
Moderate [SLS]; high [Ib] Low [SLS]; low-to-moderate lIbl No [SLS]
1 6 1 7 0.7 0.7 0 0 0
nient first-order rates of solvolysis even near room temperature (Table I); (2) the system shows an unusually large6 primary:secondary rate ratio (ca. 5 X l o 2 a t 25'); (3) a typical product mixture from, for example, I b is 2-octanol (80%), trans-2-octene (lo%), cis-2-octene (5%), I-octene (3%), and 3-octanol (2%). W e have studied the stereochemistry of this reaction using optically active Ib.7 This material gives 2-octanol with 100% inversion of configuration, but there is essentially no difference in rate and stereochemistry2 above or below its critical micelle concentration or in the presence of micellar hexadecyltrimethylammonium bromide (CTAB). However, in the presence of micellar concentrations of sodium lauryl sulfate (SLS) the reaction is strongly inhibited and there is a significant change in stereochemistry. The half-life for solvolysis of Ib increases to 50 min a t 30' (vs. 40 sec at 25'); Ia undergoes
