On the other hand, the cleavage, nitrogen inversion, and recombination of each of the copper-nitrogen bonds in [Cu(tet b) (blue)]1 2 3"1" lead to the formation of extremely unstable isomers as shown in Figure 7. The existence of each of these extremely unstable species is highly unlikely. Presumably this is the reason that there is no blue-to-red interconversion occurring concurrently with its dissociation in strongly acidic media. In addition to [Cu(tet b) (blue)]2"1", tet b forms two relatively stable red complexes with copper(II).Each of these two complexes differs from [Cu(tet b) (blue)]2"1" in the configurations of two chiral nitrogen centers.25•26 The

The crystal structure of Cu(14-ane-S4)(ClC>4)2 is reported where 14-ane-S4 represents the saturated 14-membered cyclic tetrathia ether ligand, 1,4,8,11 -tetrathiacyclotetradecane. The copper atom is centered in the plane of the four sulfur atoms with elongated bonds to two trans perchlorate groups completing the tetragonal coordination. Average bond lengths are Cu-S = 2.303 (1) Á and Cu-0 = 2.652 (4) A. The direct comparison of the crystal and solution spectra of Cu(14ane-S4)(C104)2 indicates that this complex maintains the same regular coordination geometry in the solution state. Moreover, the spectral and redox properties of the thia ether complex, similar to those exhibited by the blue copper proteins, indicate that coordinative distortion is not a primary factor in generating the distinctive properties which have been the hallmark of this class of proteins.

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3661Registry No. [Et4N]z[Moz0z(4-MeC6H4s)6(oMe)], 69532-73-6; [Et4N]z[Mozoz(sPh),(oMe)l, 69609-04-7; MoOCldthf)z, 20529-ment, and it may be that, once the first bridging ligand is displaced, subsequent attack on the remaining positions is more radd. 42-4; benzoyl chloride, 98-88-4. Supplementary Material Available: Listings of calculated atomic coordinates, anisotropic thermal parameters, isotropic thermal parameters, bond lengths, bond angles, and observed and calculated structure factors (49 pages). Ordering information is given on any Achow'edgment* We thank the SERC and Verband der ChemiSchen InduStrie for financial Support and Professor J. H. Enemark and Dr. M. R. Minelli for measuring the 9 5 M~ current masthead-page.--NMR spectra.Contribution from the Crystal structures have been resolved at room temperature for a series of Cu(I1) complexes with cyclic tetrathia ether ligands having the general formulation Cu"( [n]aneS4)(C104)z(Hz0),, where n represents the total number of carbon and sulfur atoms in the macrocyclic ligand ring (n = 12, 13, 15, 16) and x = 1 for n = 12 or 13 and zero for the other compounds.The respective space groups, lattice constants, and final R factors for these four compounds are'as follows: for orthorhombic C~~~([12]aneS~)(ClO~)~(H~0)space group PbcZ,, a = 9.010 (2) A, b = 15.775 (3) A, c = 13.380 (2) A, Z = 4, R = 0.127, R, = 0.162; for monoclinic C~~~([l3]aneS~)(ClO~)~(H~0) space group a = 18.073 (3) A, b = 13.607 (3) A, c = 18.167 (3) A, 6 = 119.759 (l)', Z = 8, R = 0.081, R, = 0.116; for monoclinic C~" ( [ l 5 ] a n e S~) ( C 1 0~)~ space group P2,/n, a = 7.994 (1) A, b = 9.167 (3) A, c = 13.978 (3) A, @ = 99.29 (3)O, Z = 2, R = 0.066, R, = 0.085; for monoclinic C~" ( [ 1 6 ] a n e S~) ( C l O~)~ space group P2,/c, a = 7.931 (3) A, b = 9.613 (5) A, c = 14.885 (5) A, 6 = 110.71 (3)O, Z = 2, R = 0.044, R, = 0.064. These structures are compared with that previously reported for C~~~( [ l 4 ] a n e S~) ( C l O , )~to provide a continuous series of homologous macrocyclic complexes in which the internal cavity progresses from dimensions that are too small to accommodate the central metal ion to those that exceed optimal size. In the compounds formed with[12]aneS4 and [13]aneS4, the Cu(I1) ion sits 0.53 and 0.38 A above the plane of the four sulfur donor atoms. In both cases the inner coordination sphere is square pyramidal, being completed by an axially coordinated water molecule. In the complexes formed with the three larger ligands, Cu(I1) is coplanar with the four sulfur donor atoms, and two C104-ions are coordinated axially to form a tetragonal inner coordination sphere. The Cu-S bond lengths increase with increasing ring size, exhibiting average values of 2.30, 2.32, and 2.36 A for n = 14, 15, and 16, respectively. In the last complex, in fact, the four Cu-S bonds are no longer equivalent: one pair of trans-Cu-S bonds is 2.33 A while the other pair is 2.39 A. In all five complexes, the axial C u -0 bond distances vary inversely with the average Cu-S bond distances so that, wi...

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