8566
Bridged Mercaptide Complexes of Nickel( 11) and Palladium( 11) with Metal-Metal Interactions John P. Fackler, Jr.,* and Wm. J. Zegarski Contribution f r o m the Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106. Received February 5 , 1973
Abstract: The structural features of three bridged mercaptide complexes, Ni2fSCH2C6Hs)z(SzCSCH2CgH5)2 (A), Pd,[SC(CH3),]2[SzCSC(CH3)3]7 (B), and Pd3(SC2H5)3(S2CSC2Hs)3 (C), are described. Each compound contains a distorted planar MS4 coordination geometry with trigonally bound bridging sulfur atoms in the bridging mercaptide groups. A displays a nonplanar syn-endo NLS?rhombus and B a nonplanar anti Pd2S2rhombus. The trimer shows a substantial distortion from the potential trigonal symmetcy for the “chair” form of the Pd& ring. The dimers A and B have met9l-metal distances of 2.795 and 3.162 A, respectively, while C shows Pd-Pd distances of 3.655, 3.307, and 3.303 A. The metal-metal distances in the dimers are not consistent with a metal-metal bond
alone being the feature controlling the gross stereochemistry of these complexes. Sulfur-sulfur interactions also appear to occur. Data were obtained diffractometrically with Cu KB radiation. Refinement produced a final R of 0.062, 0.087, and 0.058 respectively for A, B, and C. The unit cells are as follows with space groups found to be respectively 12, Pnma and P i : A, a = 15.459 (7); b = 4.6041 ( 5 ) , c = 22.116 ( 5 ) A, 6 = 97.04’, z 2; B, a = 11.719 (l), b = 23.186 (l), c = 10.806 A, z = 4; C, a = 11.573 (1)) b = 16.778 (2), c = 9.873 (1) A, cx = 93.18(1), 6 = 104.24(l),y = 122.29(1)’,~= 2.
=.
M
(SR),(CO)6 and’, [Fe2(C5Ha)2(SCH3)2(C0)2]+, a folded rhombus is found, suggestive of Fe-Fe bonding. With metal complexes in which the metal ion can be described electronically by [core]nd,8 any metal-metal interactions assumed generally have been thought t o be rather weak. l 3 However, the situation has become confused recently by some apparent structural contradictions. Both14 Ni2(S2CCH2C6H5)dand13 Ptz(SzCC6HAC3H7)A show short metal-metal distances (2.56 and 2.87 A, respectively). Also15 Ni6(SC2H5)12and16 Ni2[S(CH2CH2S)2]2 display fol$ed NizS2 quadrangles, with Ni-Ni distances of ~ 2 . A. 8 Yet the Pd2S2rhombus” in Pdz(SC6F5)l(P(C6Hj)3), is planar. After our work 2M(SKSR), +2CS2 + [M(SR)(SKSR)nJ2 (1) had begun, Villa, et al., reported the structure of Ni:elimination of CS, by this route, orginally used by Knox, (SC2H&(S2CSC?H5)2and suggested that the 2.76 A et a1.,6 generally affords crystalline materials. The Ni-Ni distance represented “the first example of bimetal thioxanthates themselves are easily prepared5 and nuclear planar NiII complex with Ni-Ni bonds.” can be stored. Thioxanthate ligands which remain In this study we report the crystal and molecular coordinated to the metal in the mercaptide products are structures of three bridged mercaptide complexes, themselves candidates for further reaction ~ h e m i s t r y . ~ Ni2(SCH2C6H5)2(S2CSCH2CsHj)2 (A), an analog of the Lippard and coworker^^^^ utilized this synthetic techcomplex studies by Villa, et a]., Pd2(SC(CH3)&nique to prepare and structurally study Fez(SR)2- (S2CSC(CH3)3)2 (B), a compound with aliphatic bridging (S,CSR), and CO,(SR)~(S~CSR)~, two compounds conmercaptide ligands, and Pd3(SC,HJ3(S2CSC2Hs)3(C), a taining mercaptide bridges. These compounds display trimeric bridged mercaptide species. Added impetus a planar M2S4rhombus. Roussin’s salt, lo Fe2(SC?H& for study of C comes from the fact that a related comalso has a planar Fe2S4rhombus. With” Fezpound, l 9 Pd3[(SCH2CH2),SI3,coatains a distinctly nontrigonal (3.66, 3.49, and 3.41 A) arrangement of pal(1) D. Coucouvanis, Progr. Inorg. Chem., 11,233 (1970). ladium atoms with Pd-Pd distances averaging close t o (2) J. A. McCleverty, Progr. Inorg. Chem., 10,49 (1968). uch has been learned during the past decade about the chemical properties of sulfur containing complexes. lHowever, detailed knowledge of structural features and chemical reactivity, particularly of the mercaptide ligand species, is still quite limited. In spite of the importance of metal-mercaptide species in biological chemistry, few nonorganometallic prototype4 compounds have been studied, largely because of the problems inherent in their synthesis. Our work5 has established that certain neutral metalmercaptide complexes may be synthesized by solution decomposition of the metal thioxanthates (eq I). The
(3) R. Eisenberg, Progr. Inorg. Chem., 12,295 (1971). (4) See B. A. Averill, T. Herskovitz, R. H. Holm, and J. A . Ibers, 3523 (1973), and references therein. Holm and coworkers now have prepared and studied an iron(II1) dimer with bridged mercaptide ligands. ( 5 ) J. M. Andrews, D. Coucouvanis, and J. P. Fackler, Jr., Inorg. Chem., 11, 493 (1972). (6) D. B. Blandon, R. Bruce, and G. R. Knox, Chem. Commirn., 557 (1965). (7) J. P. Fackler, Jr., and W. C. Seidel, Inorg. Chem., 8, 1631 (1969). (8) D. Coucouvanis, S. J. Lippard, and J. A. Zubieta, Inorg. Chem., 9 , 2775 (1970). (9) D. F. Lewis, S. J. Lippard, and J. A. Zubieta, J . Amer. Chem. SOC., 94, 1563 (1972); see also S. J. Lippard, Accounts Chem. Res., 6, 282 (1973). (10) J. T. Thomas, J. H. Robertson, and E. G. Cox, Acta Crystallogr., 11, 599 (1958). (11) L. F. Dahl and C. H. Wei, Inorg. Chem., 2,328 (1963). J . Amer. Chem. Soc., 95,
(12) N. G. Connelly and L. F. Dahl, J. Amer. Chem. Soc., 92, 7472 (1970). (13) See J. M. Burke and J. P. Fackler, Jr., Inorg. Chem., 11, 3000 (19721, and references therein. (14) M. Bonamico, G. Dessy, and V. Fares, Chem. Commun., 1106 (1969). (15) P. Woodward, L. F. Dahl, E. W. Abel, and B. C. Crosse, J . Amer. Chem. SOC.,87, 5251 (1965). (16) G . A. Beady, E. M. McPartlin, and N. C. Stephenson, Acta Crjstallogr., Sect. B, 25, 1262 (1969): D. J. Baker, D. C. Goodall, and D. S. Moss, Chem. Commun., 325 (1969). (17) R. H. Fenn and G. R. Segrott, J . Chem. SOC.A , 3197 (1970). (18) A. C. Villa, A. G. Manfredotti, M. Nardelli, and C. Pelizzi, Chem. Commun., 1322 (1970). (19) E. M. McPartlin and N. C. Stephenson, Acta Crystallogr., 25, 1660 (1969).
Journal of the American Chemical Society j 95:26 I December 26, 1973
8567 Table I.
Crystal and Data Collection Parameters A
Molecular formula Color Crystal size, mm3 Radiation used Cell dimensions a (ambient b temp) c
B
C
N~zS~C~OHZ~ PdzSsClsH36 Brown Orange 0.5 X 0.3 X 0 . 2 0.1 X 0.3 X 0.1 Nickel filtered Cu Ka (1.5418 A) 16.459 (7) 11.719 (1) 4.6041 (5) 23.186 (1) 22.116 (5) 10.806 (1) 97.04 (2)
%P,Y
+ k + 1 = 2n + 1
Systematic absences
h
Space group Molecules/unit cell Density calcd [found] Scan Scan speed, deg/min Background, sec No. of reflections Nonzero reflections PA,cm-' Transmission coeff
12(C2; Cz3, NO. 5) 2 1.52[1.51 (l)] 8-20 1 15
1763 1200 59.5 a
+
Pd3SiG5Hm Orange 0 . 4 X 0 . 1 X 0.1 11.573(1) 16.778 (2) 9.873 (1) 93.18 (l), 104.24 (l), 122.29 (1)
hOf, h = 2n 1 Okl, k 1 = 2n 1 Pnma(Dzbi6, No. 62) 4 1.63[1.65(2)] 8-20 2 15 2346 2000 186 0.09-0.32
+
+
(PiNO. 2) 2 1.98 [2.01 (2)J 8-28 2 10 4200 3769 218 0.14-0.40
a Absorption corrections not performed. While the theoretical range in the transmission coefficient is 0.2-0.5 for the crystal used, the actual range for the cylindrical crystal is probably much smaller.
Table 11. Refinement Information
A Compound Initial solution
B
C
NizSsC3oHZs Pd~SsClsHas Pd&zCi5H3n Patterson, Patterson Patterson, Harker gradient section sharpened
Isotropic convergence"
Ri Rz Anisotropic convergence Ri
R2 Error at unit wtc Diff Fourier max int, e/Aa Final max shifts in units of u
0.11 0.13
0.14
0.10
0.062b 0.082 0.67
0.087 0.113 0.91
0.058 0.076 0.86
0.2
1.5
0.5
0.3
0.6
Least-squares minimized on Z(IF,I - )F,1)2; Rl = ZwI(lF,I IF,I)//F,/)I; R2 =, [Zw(lFoj - /F,1)2/ZwFozl'/~. * Hydrogen atoms included at 0.95 A. A Cruickshank l/[o(F)]2 weighting scheme28 was used for refinement near convergence. a
the 3.5 A value reported for the bridging pentafluorothiophenol dimer.l8 Yet Tiethof, et a1.,20 report [CU((CH~)~PS)CI]~, ostensibly a [core]3d10 metal ion system, to contain a similar M3S3chair-form cyclohexane type ring but with nearly equal (3.545, 3.545, and 3.610 A) CuI-Cu' distances.
Experimental Section Bis(benzy1
NizA crystal (Table I) prepared as described5 (mp 214-215"; mol wt calcd 762, found 791, osmometrically in CHCl,) was mounted parallel to b on a glass fiber. Precession photographs with Mo Ka, oscillation, and Weissenberg photographs with Cu K a established the lattice. Centering was done with 17 reflections. Data subsequently were collected on a Picker four-circle automatic diffractometer with two intensity standards each 50reflections. Solution and Refinement of Structure. Initial refinement was performed inz1 space group 12. The groups I m and 12/m, which
trithiocarbonato)di-fi-(benzylthio)-dinickel(II),
(SCHzC&15)z(S2CSCH2Cd-15)~ (A). Data Collection.
(20) J. A. Tiethof, J. K. Stalick, P. W. R. Corfield, and D. W. Meek, J. Chem. Soc., Chem. Commun., 1141 (1972). (21) "International Tables for X-Ray Crystallography," Vol. I, Kynoch Press, Birmingham, England, 1962.
also are acceptable from the systematic absences, were discounted because of the probable molecular structure. Refinement (Table 11) established the choice to be correct. Scattering factors of Cromer and Waber22 for Ni, C, and S and those of Stewart, et for H were used. The nickel atoms were located at 2x, 0,2y. Unobserved reflections were not included in the final structure factor calculation.24 Positional parameters and thermal parameters are presented in Tables 111 and IV. See paragraph at end of paper regarding supplementary material. Table 111. Atomic Positional Parameters for
INi~SCHzCsH5~~SzCSCHZCeHs~lza sb
Atom
X
Y
Ni s1 s2 s3 s4 CL CM CT Ca Cb cc Cd Ce Cf c1
0.4379 (1) 0.3170(2) 0.4308 (1) 0.5600(2) 0.2788 (2) 0.1899 (10) 0.6258 (8) 0.3390 (8) 0.123 (1) 0.094 (1) 0.029 (1) -0.002 (1) 0.023 (1) 0.086 (1) 0.688 (1) 0.676 (1) 0.732 (2) 0.800 (2j 0.817 (1) 0.760 (1)
0.5000 (0) 0,7141 (7) 0.6933 (7) 0.3086 (5) 0.0112 (8) 0.1095 (20) 0.5201 (22) 0.8172 (20) -0.113 (3) -0.216 (5) -0.420 (5) -0.502 (7) -0.409 (6) -0.206 (4) 0.321 (3) 0.182 (4) -0.008 (7) -0.072 (5) -0.064 (6) 0.246 (4)
c2
c3 c4 c5 C6
z
0.4509 (1 0.4413 ( 2 0.3589 (Z 0.4584 (1 0.3184 (2 0.3554 (1 0.4118 (f 0.3727 ( C 0.354 (1) 0.406 (1) 0.401 (1) 0.346 (2) 0.295 (1) 0.298 (1) 0.391 (1) 0.336 (1) 0.313 (1) 0.351 (1) 0.405 ( 1 ) 0.427 (1)
a Numbers in parentheses in tables are estimated standard deviations in the least significant figure. * The coordinates are expressed as fractions of the unit cell edge.
(22) D. T. Cromer and J. T. Waber, A c f a Crystallogr., 18, 104 (1965). (23) R . F. Stewart, E. R. Davidson, and W. T. Simpson, J . Chem. Phys., 42,2175 (1965). (24) The programs used were PICK 1 and 2, diffractometer setting
programs by I,(P(C~H,),>,with B (34) It is interesting to note that orbital symmetries in the syn-endo nickel complexes permit positive S . . S overlap. Such overlap is exfurther emphasizes the structural relationships occurring pected to be smaller in the anti bridged mercaptide species. In addiin the MzS2 quadrangles which control interatom tion to the compounds reported by Lippard,7.* the compounds [Mo(~~-CSH~)(SCHS)Z]Z, N. G. Connelly and L. F. Dahl, J. Amer. Chenl. distances. In the pentaflup-othiophenol derivative tGe Soc., 92, 7470 (1970), and [(lr-CsH~)zNb(SCHa)z]zNi(PFe)z. W. E. Pd-Pd distance is -3.54 A with S . . S being -3.2 A. Douglas, M. C. H. Green, C. K. Prout, and G. V. Rees, Chem. Commun., ( A - C ~ H ~ ) ~ N ando ~ ~ ((CSH5N3CSH&Ni2. C~)~ The distance observed (2.733 A) for the trinuclear 3 3 Ni[Ni(NH2CHzCHzS)2]zClz is -4% shorter than that found in the neutral benzyl and ethyl mercaptide dimers, while the distance in the hexamer'j (Table XIII) is somewhat larger.
-
896 (1971), contain anti mercaptide bridges.
(33) C. H. Wei and L. F. Dahl, Inorg. Cliem., 9, 1878 (1970).
(The latter compound has
a tetrahedral NiS4 geometry.)
Fackler, Zegarski
Bridged Mercaptide Complexes of Ni(Il) and Pd(II)
8574
atoms form a closed shell. In this latter compound the copper atoms form a triangle with -D3 symmetry. *O Assuming that some metal-metal interaction occurs in the trimers, an asymmetric mixing of empty orbitals energetically close to the filled ground orbitals, a secondorder Jahn-Teller interaction, 35 may account for the distortions observed. An asymmetric mixing is possible between empty and filled d orbitals of the palladium atoms. If, for example, one assumes that the dominant orbital splitting of palladium d orbitals is caused by a square arrangement of sulfur atoms, the metal dz+2 orbitals are empty but only an electron volt or so removed from the filled d orbitals. In D3 symmetry these d,z-y2 orbitals transform as A, and E. The highest filled orbital set is likely dZzwhich transforms as AI and E. The vibrational coordinates which change the metal-metal distances transform as A, and E, also. Consequently this model would lead to an asymmetric mixing of the filled dzz with the empty d,+,2 orbitals by means of the e vibrational coordinate. Displace(35) R. Mason, Chem. SOC. Rev., 1, 431 (1972), and references therein.
ment along this coordinate leads to removal of the trigonal symmetry. While it is impossible at present to determine quantitatively the magnitude of the effect, the features required qualitatively are present in the trimeric palladium complexes. Acknowledgment. Support from the National Science Foundation, GP-11701, and the National Institutes of Health is gratefully acknowledged. W. J. Z. acknowledges the National Science Foundation for supporting a predoctoral fellowship in chemistry at Case Western Reserve University. Discussions of the second-order Jahn-Teller effect with W. Abrahamson and R. Mason were particularly helpful. Supplementary Material Available. A listing of structure factor amplitudes will appear following these pages in the microfilm edition of this volume of the journal. Photocopies of the supplementary mateiial from this paper only or microfiche (105 X 148 mm, 20X reduction, negatives) containing all of the supplementary material for the papers in this issue may be obtained from the Journals Department, American Chemical Society, 1155 16th St., N.W., Washington, D. C . 20036. Remit check or money order for $3.00 for photocopy or $2.00 for microfiche, referring to code number JACS-73-8566.
13CNuclear Magnetic Resonance Studies of Organometallic Compounds. I. trans-Methylplatinum( 11) Derivatives’ M. H. Chisholm, H. C. Clark,*2 L. E. Manzer, J. B. Stothers, and J. E. H. Ward Contribution f r o m the Department of Chemistry, The University of Western Ontario, London, Ontario, N6A 3K7, Canada. Received June 16, 1973 Abstract: The 13C nrm spectra have been obtained for three series of trans-methylplatinum(I1) complexes of the and trans-(CH3)Pt(P(CH3)~type frans-[(CH3)Pt(As(CH3)&L]+PF6-, trans-[(CH3)Pt(P(CH3)2(C6H5))2L]+PF6-, (C6H5))& where L is a neutral ligand and X is an anionic substituent. The 13Cshieldings and 13C-195Pt coupling constants are discussed and compared with data derived from lH nmr spectra of the complexes. Evidence is ob,. tained which supports the rehybridization theory of the nmr trans influence.
I
n principle, there are certain distinct advantages of using 13Cnmr rather than ‘H nmr spectroscopy for the investigation of organometallic compounds. 3C nmr parameters have been demonstrated to exhibit considerably greater sensitivity to changes in bonding and molecular structure. The use of off-resonance and noise-modulated proton decoupling enables first-order assignments to be made without the sometimes tedious spectral analysis. Moreover, 13C nmr offers a unique method of directly observing the effects of stereochemical and bonding alterations of coordinated groups such as acetylenes, carbonyls, isocyanides, and olefins, which contain carbon atoms immediately bonded to a transition metal. Our preliminary l3C nmr investigations4a5 have at(1) This work may also be regarded as part 35 of the series 13C Nmr Studies. Part 34: J. B. Stothers and C. T. Tan, Can. J. Chem., in press. (2) Author to whom correspondence should be addressed. (3) (a) J. B. Stothers, “Carbon-13 N.M.R. Spectroscopy,” Academic Press, New York, N. Y., 1972; (b) G. C. Levy and G. L. Nelson, “Carbon-l 3 Nuclear Magnetic Resonance for Organic Chemists,” WileyInterscience, New York, N. Y . , 1972. (4) M. H. Chisholm, H. C. Clark, L. E. Manzer, and J. B. Stothers, Chem. Commun., 1627(1971).
Journal of Ihe American Chemical Society
tempted to exploit this potential. In those studies, we examined a number of organoplatinum derivatives and were able to show that valuable information could be derived from the coupling of the lg5Pt ( I = l/*, 34Z natural abundance) and 13Cnuclei, as well as from the 13C shieldings. Although 13C nmr investigations of organometallic compounds are now relatively common, few reports6-11 have appeared which involve detailed examination of series of closely related complexes. We now wish to describe a systematic study of three series of o-bonded platinum(I1) complexes, (I) trans[(CH3)Pt(As(CH3>3),L]+PF6-, (11) trans-[(CH3)Pt( 5 ) M. H. Chisholm, H. C. Clark, L. E. Manzer, and J. B. Stothers, J . Amer. Chem. Soc., 94,5087 (1972). (6) P. C. Lauterbur and R. B. King, ibid., 87,3266 (1965). (7) 0. A. Gansow, B. Y . Kimura, G. R. Dobson, and R. A. Brown, ibid., 93,5922 (1971). (8) 0. A. Gansow, D. A. Schexnayder, and B. Y. Kimura, ibid., 94, 3406 (1972). (9) G . Singh and G. S . Reddy, J . Organometal, Chem., 42,267 (1972). (10) (a) J. A. Connor, E. M. Jones, E. W. Randall, and E. Rosenberg, J. Chem. Soc., Dalfon Trans., 2419 (1972); (b) G . M. Bodner, S. B. Kahl, K. Bork, B. N. Storhoff, J. D. Wuller, and L. J. Todd, Inorg. Chem., 12,1071 (1973). (11) C. D. M. Beverwijk and J. P. C. M. van Dongen, Tetrahedron Lett., 42,4291 (1972).
1 95:26 1 December 26, 1973
