1051
Crystal and Molecular Structure of Stable Platinum(0) Complexes of Cyclohexyne and Cycloheptyne G . B. Robertson and P. 0. Whimp* Contributionfrom the Research School of Chemistry, The Australian National University. Canberra, A.C.T., 2600, Australia. Received April 20, 1974
Abstract: The crystal and molecular structures of stable Pt(0) complexes of cyclohexyne (C6Hg) and cycloheptyne ( C ~ H I O ) , of the form [(cycloalkyne)Pt(P(C6H5)3)~]have been determined by three-dimensional X-ray structural analysis using data collected b counter methods. The cyclohexyne complex crystallizes in the triclinic space group P1 (C,), No. 2), with a = 9.875 (2) b = 18.141 (4) A, c = 10.081 (2) A, a = 89.99 (2)O, /3 = 80.68 (2)O, y = 78.28 (2)O, and Z = 2, while the cycloheptyne analog crystallizes in the monoclinic space group P 2 1 / c (C2h5, No. 14), with a = 8.951 (2) A, b = 33.523 (8) A, c = 13.095 (3) A, /3 = 114.24 (2)', and 2 = 4. Both structures were solved by conventional heavy-atom techniques, and were refined by block-diagonal least-squares methods. Only those reflections with I / a ( l ) 2 3.0 were considered to be statistically significant. For [(cyclohexyne)Pt{P(C~H5)3~~], the weighted and unweighted R factors were 0.044 and 0.040, respectively (for 5 157 independent reflections), while for [(cycloheptyne)Pt{P(C&)3]2], the corresponding R factors were 0.030 and 0.024 (4918 unique reflections). The coordination at the central platinum atom of both derivatives is essentially square planar, with the triphenylphosphine groups occupying cis coordination sites. The dihedral angles between the two three-atom and [(cycloplanes defined by [Pt,P(1),P(2)] and [Pt,C(l),C(2)] are 4.4 (3) and 7.9 (3)' for [(cyclohexyne)Pt{P(C6H~)3]~] heptyne)Pt{P(C6H5)3]2],respectively. In the cyclohexyne derivative, the Pt-P distances are 2.264 (2) and 2.271 (2) 8, (cf. 2.264 (1) and 2.270 (1) A for the Pt-P distances in the cycloheptyne analog), while the Pt-C distances are 2.034 (7) and 2.044 (7) A (cf: 2.035 (4) and 2.064 (4) A for the corresponding distances in the cycloheptyne derivative). For [(cyclohexyne)Pt{P(C6H5)3)2], the acetylenic C=C distance is 1.297 (8) A, while for [(cycloheptyne)PtlP(C,jH5)3)2],this distance is angles average 127.3' for cyclohexyne and 138.8' for 1.283 ( 5 ) A. Within the coordinated cyclic acetylenes, the C-C=C cycloheptyne.
1,
The smallest cyclic acetylene which can be isolated in the free state is cyclooctyne, although there is some indirect evidence for the existence of cycloheptyne and cyclohexyne as short-lived reaction intermediates.] The preparation and isolation of stable platinum(0) derivatives of cyclohexyne and cycloheptyne have been previously describedS2 Single-crystal diffraction studies of [ (cyc1ohexyne)Pt(P(C6H5)3)2] and [(cycloheptyne)Pt(P(c&)3)2] have now been completed and these confirm the near identity of bond lengths and bond angles in the metal atom first coordination ~ p h e r e s .Indeed, ~ the similarity of the metal-ligand geometry has recently been found to extend to the cyclooctyne analog [(C~HI~)P~(P(C~H~)~)~I,~ and also to the acyclic acetylene platinum(0) complexes [ ( C ~ H ~ C G C C O ~ C H ~ C H ~ ) P ~ ( P ( C ~ Hand S ) ~ ) ~[p-NOrC&C=C] C02CH2CH3)Pt(P(C6H5)3)2].5 We now report detailed structural data for both [(C,Hs)Pt(P(C6Hs),)z] and [(C7HlO)Pt(P(C6H5)3)21.
(LP)= [cosz 29
+
cos2 %,]/[sin
Collection and Reduction of X-Ray Intensity Data. Approximate unit cell dimensions for each compound were obtained from preliminary Weissenberg (Okl, lkl) and precession (h01, h l l , hkO, hkl ) photographs. Photographs for the cyclohexyne complex showed neither- systematic absences nor diffraction symmetry higher than C, ( l ) , indicating a_triclinic space group. Choice of the centrosymmetric space group P1 ( C t l ,No. 2) was confirmed by the successful solution and refinement of the structure. In contrast, the systematic absences found for the cycloheptyne analog (i.e., h01 data, I = 2n 1; OkO data, k = 2n l ) , uniquely define the centrosymmetric monoclinic space group P21/c ( C 2 h 5 , No. 14). With 2 = 2 for the cyclohexyne adduct, and Z = 4 for the cycloheptyne analog, neither molecule has any imposed crystallographic symmetry constraints. Full details of the crystal data for both derivatives are listed in Table I. Reflection data for both [ (CyClOheXyne)Pt{P(C6H5)3~~]and [(CyClOheptyne)Pt(P(c6H~)~t2] were collected on a Picker FACS-I fully automatic four-circle diffractometer. In both cases, crystals were mounted on quartz fibers and were aligned with the crystallographic a axis and the instrumental @ axis approximately coincidental. Accurate unit cell dimensions and crystal orientation ma-
+
Robertson, Whimp
/
2e(i + cos2 ze,)]
where 0 and 6, (=13.25') are the Bragg angles for the reflection and monochromator, respectively. The corrected intensities were assigned individual estimated standard deviations.
dFk) = {[o(l)/(LP)12 + where
+
Experimental Section
+
trices were obtained from the least-squares refinement6 of the 26, w , x, and @ values obtained for 12 carefully centered high-angle reflections in each case. The errors quoted in the cell dimensions result from the least-squares process described above. Full details of the experimental conditions and data collection methods used are outlined in Table 11. During data collection, the three standard reflections for each compound showed a regular, isotropic, time-dependent loss of intensity. Before further calculation, reflection data for both complexes were corrected for these decomposition effects. Data were reduced to values of IFd using the program SETUP. The Lorentz-polarization correction is given by
bl~n/~)21~'2/2/~n/
+
a@)= [ C T (tJJb)2(B1 B2)j"Z (LP) is the Lorentz-polarization correction, CT is the integrated reflection intensity, B1 and B2 are the individual background counts, t p is the reflection counting time, t b is the total background counting time, and p (=0.001 is an arbitrarily assigned factor to account for instrumental "unknowns." Reflection data for which the individual background counts differed significantly [ [ . e . . if lB1 B21/(B1 B2)'I2 2 4.01 were discarded. The remaining reflection data were sorted to an order convenient for the efficient operation of subsequent programs using the program SORTIE. At the same time, equivalent reflection forms were averaged, and those reflections for which I / u ( I ) < 3.0 {where I = [CT - ( t p / fb)(B1 B2)]) were rejected as being unobserved. The statistical R factors for the terminal data sets defined as R , = Z u S ( F o ) / Z IFd, [where u,(Fo) = u(l)/Z(LP)(IFd)], are 0.012 and 0.014 for [(CYclOhexYne)Pt~P(C6H~)3~2] and [(cyc~ohept~ne)Pt~P(c6Hs)3t2~, respectively. Solution and Refinement of the Structures. Both structures were solved by conventional Patterson and Fourier syntheses and were refined by block-diagonal least-squares methods. A detailed description of the course of the refinements is given in Table 111. Atomic scattering factors for the nonhydrogen atoms, with those for Pt and P corrected for the real and imaginary parts of anoma-
-
+
+
Stable Platinum ( 0 ) Complexes of Cyclohexyne and Cycloheptyne
1052 Table I. Crystal Data
C6
9.875 ( 2 ) b A 18.141 (4) d c 10.081 (2) A a 89.99 (2)" 80.68 (2)" P 78.28 (2)" Y Formula weight 799.80 1 . 5 2 (1) g cm-3 Pobsd 1.523 g cm-3 Pcaled Z 2 Unit cell volume 1143.87 A s Space group P1 (Ctl, No. 2) Imposed symmetry None Crystal dimensions 0.225 X 0.150 X 0.070 mmc Absorption coeffi87.62 cm-1 cient (Cu K a ) a b
-
8.951 (2) A 33.523 (8) A 13.095 (3) A 114.24 (2)"
813.83 1.50 (1) g ~ m - ~ 1.508 g (3111-3 4 (a) ib) 3583.05 A 3 Figure 1. The overall stereochemistry and atom numbering schemes P 2 1 / ~(Czh', NO. 14) used for the cyclic alkyne platinum(0) derivatives: (a) [(cyclohexNone yne)PtlP(GH5)3}2]; (b) [(cycloheptyne)Pt{P(C6H5)3J2].(In both fig0.275 X 0.075 X ures, the symbol C has been omitted from phenyl carbon atoms.) 0.137 mmc 85.24cm-l The hydrogen atoms were assigned fixed isotropic temperature factors 10% greater than the carbon atoms to which they are bondThe "reduced" cell, obtained from a Delaunay reduction (B. ed ( i . e . ,B H = 1.1Bc A2). No attempt was made to refine the hyDelaunay Z . Kristallogr., Kristallgeom., Kristallphys., Kristailchem., drogen atom coordinates or temperature factors which were recal84,109(1933)) isa' = 18.811 A, b' = 12.918 A, c' = 10.081 A, a' = culated prior to each refinement cycle. On the final refinement 131.03", = 94.87", y' = 100.68", volume of "reduced" cell = cycle for each cyclic acetylene complex, no individual parameter 1743.87 A3. The structure was solved using the nonreduced cell, shift was greater than 0.1 of the parameter estimated standard deand all subsequent data refer to this nonreduced cell. Estimated viation. (Estimated standard deviations are obtained from inverstandard deviations (in parentheses) in this and the following tables, sion of the block-diagonal matrices.) The standard deviation of an and also in the text, refer to the last significant digit(s) in each case. observation of unit weight, defined as [Xw[lFd - IFd12/(me Crystal dimensions quoted are parallel to a, b, and c . respectively. n ) ) ' / 2(where M is the number of observations and n is t h e number of parameters varied) is 2.40 for [(cyclohexyne)Pt(P(C~H~)~~2] lous s ~ a t t e r i n g , ~were , ' ~ taken from the usual compilation.' Scatand 1.44 for [(cycloheptyne)PtlP(C6H5)&]. An examination of tering factors for hydrogen were taken from the tabulation of IFd and IFd showed no evidence of serious extinction effects, and Stewart, et al. l 2 consequently, no correction was applied. Similarly, a weighting During the refinement process, the reflection data for both descheme analysis showed no serious dependence of w[lFd - IFd]' rivatives were corrected for absorption effects, using grid sizes of on either IFd, A-' sin 8, or Miller index. The final electron-density 12 X 8 X 4 and 14 X 4 X 8 points (respectively parallel to a, b*, difference Fourier maps showed no unusual features. For the cyc*) for [(cyclohexyne)Pt(P(C~H~)3}2]and [(cycloheptyne)Ptclohexyne derivative, the highest residual peak was 1.2 e/A3, near {P(c6Hs)3)2], respectively. The transmission facto; (applied to the platinum atom; the remaining peaks were all less than 0.5 e / IFd2) varied from 0.2237 to 0.6328 for the cyclohexyne derivative A3. For the cycloheptyne analog, there were no peaks greater than and from 0.3029 to 0.5892 for the cycloheptyne analog. 0.5 e/A3. When fixed hydrogen atom contributions were added to the reTable IV lists the final atomic positional and thermal paramefinement, it was assumed that the C-H distances were 1.087 A. ters for [(cyclohexyne)Pt(P(C6H5)3/2],while those for [(cycloTable 11. Data Collection Details heptyne)Pt{P(C6H5)& are listed in Table V . The final values of 10 IF4 and IOlFd (in electrons) have been deposited. (For details regarding the availability of supplementary material, see the paraRadiation Cu K a Cu K a graph at the end of this paper). 1.5418 +& 1.5418 A Wavelength Computer Programs. The data reduction and sorting programs Monochromator Graphite crystal Graphite crystal SETUP and SORTIE were originally written by Dr. B. M. Fox3.0" Takeoff angle 3.0' man, but were modified (Whimp) for operation on the UnivacCrystal to counter 28.5 cm 28.5cm 1 108 computer. The Fourier and absorption correction programs, distance ANUFOR and ACACA, respectively, have been described preScan speed 2"/min 2 "/min viously. l 3 The block-diagonal least-squares program, BLKLSQ,I3 Scan method 6-26 scans 8-20 scans uses either 4 X 4 or 3 X 3 and 6 X 6 matrices. Figures were proFrom (20 - 1.2)" to From (28 - 1.15)" t o Scan widtha duced with ORTEP.I4 Calculations were carried out on the (20 1 . 2 A)' (20 1.15 A)' CDC3600 computer of the CSIRO Division of Computing ReTotal background 20 sec 20 sec search, Canberra, and the IBM360/50 and Univac-I108 computcount timeb ers of The Australian National University Computer Centre. "Standard" 3 every 40 3 every 40 reflections Results "Standard" indices (0,12,3) (7,6,0)(O,iT,s)(7,1,7) (0,18,5) (8,0,?) 12z isotropic decay 8 z isotropic decay Crystal stability Description of the Structures. T h e crystal structures of during data during data both [(cyclohexyne)Pt{P(C6H~)~j~] and [(cycloheptyncollection collection e)Pt(P(CsHs)3]2] a s defined by t h e unit cell dimensions, 20 scan limit 124" 124" Form of data i k l , hLl,.Aki, hlil, hki space group symmetry operations, a n d a t o m coordinates collected consist of discrete monomeric molecular units having neiTotal number of 6343 6674 ther crystallographic nor virtual symmetry higher t h a n CI. data collected T h e r e a r e no unusually short intermolecular atom-atom Number with 5157 4918 contacts. T h e stereochemical arrangement of one molecule I / U ( I ) 2 3.0 of [(cyclohexyne)Pt(P(C6H~)3)~], together with t h e a t o m P2 0.001 0.001 numbering scheme, is shown in Figure l a , while a perspeca The scan range was asymmetric. A is the 20 separation (in detive view of this molecule is given by t h e stereopairs of Figgrees) of the Cu K a l and Cu Kat peaks at the 20 value of the reflecure 2. Similar details for the cycloheptyne analog a r e shown tion concerned. b Backgrounds were counted on either "side" of in Figures I b a n d 3. T h e thermal ellipsoids have been each reflection at the scan range limits and were assumed to be linear between those two points. drawn t o include 50% of t h e probability distribution, and,
e'
'
+
+
Journal of the American Chemical Society
+
+
/
97:5
/
March 5, 1975
1053 Table 111. Course of Refinement [(CeHs)Pt { P(C6Hj)a } 21 Set no.
Conditions
[(C,HIO)Pt{P(CsHj)a)21 R RW
R”
RW
0.086
0.097
0.066
0.073
0,060
0.074
0.052
0.061
0.041
0.046
0.041
0.056
0.034
0.046
0.024
0.030
~~
1 2
3
4 5
6 7
All atoms isotropic, hydrogen atoms not included, equal (unit) weights Pt and P anisotropic, C isotropic, hydrogen atoms not included, equal (unit) weights. At this stage of refinement, the reflection data were corrected for absorption effects Pt and P anisotropic,* C isotropic, hydrogen atoms not included, equal unit weights. were Individual weights [w = l/aZ(Fo)] introduced at this point and were used in all subsequent refinement cycles Pt and P anisotropic, C isotropic, no hydrogen atom contributions Pt and P anisotropic, C isotropic, fixed hydrogen atom contributions Pt, P, and C anisotropic, no hydrogen atom contributions Pt, P, and C anisotropic, fixed isotropic hydrogen atom contributions included
0.055
0.067
0.048
0.061
0.040
0.048
R = ZilF,, - IF,///ZIF,I; R, = [Zw(IF,/ - [ F c / ) 2 / Z w / F o l * ] ”the ~ ; function minimized during least-squares refinement was Zw((FoI lFc()2.b The anisotropic thermal parameter takes the form exp[--(Pllh2 &k2 P d 2 2P12hk 2P13hl-k 2Pz:kl)l.
+
+
+
+
Figure 2. A stereoscopic view of [(cyclohexyne)PtlP(C6H5)312]
Figure 3. A stereoscopic view of [(cycloheptyne)Pt(P(ChH.)312].
for clarity, hydrogen atoms have been omitted from all figures. Both complexes exhibit near identical coordination a t the central platinum atom; the ligand arrangement is essentially square planar, with t h e donor phosphine groups occupying mutually cis coordination sites; t h e coordinated alkyne groups a r e only slightly rotated from t h e P-Pt-P planes (vide infra). Bond length and bond angle d a t a a r e listed in Tables VI-VIII. It should be noted t h a t a s atom-atom correlations have been neglected, both in the (block-diagonal) least-squares refinement process, a n d in t h e subsequent cal-
Robertson, Whimp
/
culation of bond distance and interbond angle estimated standard deviations, t h e tabulated esd’s will certainly be underestimated. T h e results of weighted least-squares planes calculations a r e collected in T a b l e IX.I5 Torsion angles within each cyclic alkyne ring a r e collected in T a b l e X.
Discussion In t h e complexes [(cycloheptyne)Pt{P(c6H~)~)~] and [(cyclohexyne)Pt(P(C6H~)&],t h e disposition of ligands in t h e first coordination sphere is entirely characteristic of alkyne- and alkene-platinum(0) (d‘*) complexes. I n both de-
Stable Platinum ( 0 ) Complexes of Cvclohexyne and Cycloheptyne
1054 Table IV. Fractional Atomic Positional and Thermal Parameters for [(cyclohexyne)F't(P(CBH&
(a) Refined Positional and Anisotropic Thermal Parameters &IO*
I
1
1
BriAi I
BEll22
BElAll
OLlAl2
nLTAll
8LlAZl
Pl P I I I
PI21 C I I I
0. I 2 9 5 1 6 1
0.3011131
U.003512I
0.00101*l
-o.oot*iir
-0.0015151
CIZI
0*2010)bI
0.2359131
O ~ U O J b 2I I
0.00141bI
.0.0003111
0.0007151
C I I I
0.35051 b I
0.2OIOICI
0.00L1711l
U.Ol2bl~l
-0.0002111
0*000b1bI
o.oou* I I I o.oooni *I
C I Y I
0,19l917l
0.1511 141
0.u0731111
0.OlIbltl
-0,00271*1
D - 0 0 2 7 171
O.OOl9151
(151
0.1354181
0.33b1IYl
0 . 0 0 1 1 I 11
0~01b51101
-0~OOlb151
-0.0021181
0*0011'1151
CIbI
0,1711Vl 7 1
0.35831111
0.00'451ll
0.0117171
-0.0025111I
-0*001b1bI
0.0025111
0.0011111
C I I I I I
-0.177115l
0.lZ411Ill
t . 0 0 2 4 I 21
0*0100lb I
.O.OOO111Il
CIII2I
-0.2blbIbl
0 . 1 2 5 2 1 11
0 . 0 0 3 5 12 I
0.01111l7I
-0.0017131
-0.001111bI
0.OOObIII
CIIIII
-0.~n9vi71
0.10351?1
0.00*4111
O.OIbbI9I
-O.0022I11l
-0.OOIbl7l
O.OOI*l*l
CI11'1I
-0.*319171
o.on1~141
0.003nizi
0.0212l1ll
-0.0022I4I
-0.ooivini
0.00 1 9 1 4 I
Cl1151
-0.1505171
o.onioi'1
L.OP11LI I 3 I
0.C151l9l
-O.OoIll*l
CIIIbI
-0~221817l
o.igini3i
0*001112I
O.UIIII7l
-0.0009lIl
-0.00101bl
0.00 I 7 II I
CII2II
0.10bb161
O~Ob11131
C.0025121
0.008215l
-O.ooO3of
-0.0002151
0.000712l
CII22I
0.2513lb1
0.05Y9l3I
-0.0002111
-0.OOOZIbI
CII23I
U.340717I
i
o.uo11121
0.0111LIYI
-0.00b8111
0.00111 I 1 I
0.0157I9l
0.00011*1
O~OOU1115I
0.001 1 1 7 1
0.0004lII
0.00.'2111l
ll.OOObI
11
0.001 1 1 7 1
.0.00011I*l
O.0021181
.0.00101*1
CII24I
0.29071ni
-0.ObVlll11l
o.uo3vllI
0.01b31101
Cl1251
0. I~ P B I P I
-O.ObbYl4I
C.OO1312I
0.02U8l1111
-0.000.111l
0.0017111I
-0.002L151
CIIZbI
0.0577
-0.0003131
O.OO3~12l
0.01871101
-0.0011131
0.0011 I 7 I
.0.00211*1
CIIJII
O.O*78ILI
0.lbbOIII
o.ooznizi
Cl132I
0~0156lbl
0.2412I11I
O.UO'*I
CllJ3l
O.O*5918I
0.248JI1L
O.OOb5
C I I l * I
0.113518l
O.IPl215l
0.00811*1
Cl1351
0.l5lIlPI
0*1207151
C113bl
0.1167171
CI21II
I7I
0.00111* I
O . O O ~ ~ I L I
.0.0012111
-0~0005t5I
21
0.011417I
-0.002110l
0*00081bI
.O.O02*lII
14 1
D.OI12171
-0.001oI*1
~O.UO~bl7I
-0.0027111I
O~OlOll7l
-0.00511b1
-0.00111I7l
-0.000Il111
3 ~ 0 0 b Y 1 ~ l
0.011'1l1l
-0.00Ju15I
-o.o0*51ni
u.ooini*i
0.10771*1
P.OOYII21
0.0109171
.0.0018111I
.0.0012I7I
0.001 21 3 1
-0~Ib51151
0.31501 II
I~O02512l
0.01011bI
-0.0001151
0.00021~l
0.000112l
0.0001111
0.00011 I 1I
c12121
-0.11843lbl
0.lIOI1111
0.00111l2l
O.Ollll7l
-0.0011111
-0.00111bI
c12131
-0.b057I7I
0.30011 11 I
o.oo*niii
0~0170IIOI
.0.001*I*I
-0.OOI2l7l
CIZl11l
-0~b038171
0.~77n141
-0.0015111I
0.0042 I 7 I
-0.485017l
0.27511111
o.ooinizi o.oo3n i I I
0.U153l.l
c12151
0.0115l71
.o.oooni+i
0.002a1 b I
O.OOObI I I
C121bl
-0.Ibb7lbl
0.293IIII
0.0032121
0.00951 b l
.0.00051ll
0.000115L
0.000bl3l
C O Z I I
-O.I9lIIbl
0,420v131
0~002b121
0.0093I b I
-0.0007l1l
-0.0015151
0 . 0 0 0 v I1 I
CI222l
-0.06Lbl7I
o.4'1oioi
0.00~2121
0.0131lUl
-0.0019lbl
0.00u0 I l l
Cl223l c122111
-0.0503111l
0.50511 I11 I
otoo114 II I
O~Olb2IIOl
.0.0OIOIlI .0.0022111I
-O~lb8519I
~ e 5 4 n v I ~ l
O.OOIll2l
0.OII21Ul
-0.OoIvl4l
-0.00I91.1
Cl2251
-0.29b519l
0.530'1141
0.0028 I2 1
o,oiltnoi
-0,00071(rl
0 . 0 0 2 4 1.1
.0.OOO7lII
CIZZbI
-o.iooniii
OoYb75III
0.OOlOI2I
o.oi1701
- 0 . 0 0 0 7 1 I1
0.00U5I 7 I
-0.000101
C1211I
-0.25011bI
0.17011ll
0.001512l
0~00951bI
-0.00011l1l
-0.00011I5I
c12121
.0.295319l
0*11*blI11l
0.003PL3I
0.011120l
-0.O001111I
-0.00311111
0.0022l11 I
c12111
-O.J~I~IIOI
O.*b7BI5I
0 . 0 0 5 9 19 I
0*01751111
-0.0005lb1
-0.00b1IIlI
0*00115151
CIZIYI
-0.12I01vl
014IblI5I
o r n o o n eI 5 I
O.Ol2ller
-0.00101bI
.0.00JY181
0.00118 1 5 I
C1215I
-0.279IIOI
0.1*1215l
0.0085
0.0I01I7l
-0.00111151
-0.0019171
0, 000515l
CIZIbI
-0.2402171
0*3l711l'1l
0 . 0 0 5 0 1 1I
-0.DOOb1YI
-0~002017l
0.00011111
I 11 I
0~OI05171 ~
~~
-0,0037181
~~~~~~~~~
.0.00011111
.0.00021~l
0. OOOl 1'1 I -0.0009llI
0.0009l1 I
~~
(b) Calculated Hydrogen Atom Coordinates and Fixed Isotropic Thermal Parameters" ATOM
i
1
2
BIAv.21
ATOM
a
1
1
BIAr.21
~~
0.1117
0.201
5.1
~IIIII
aloin
0.1011
Dab71
H1321
0.lbO
O,I*b
-0.Ob5
5r I
HI13111
0,119
0.201
0.7*1
5.8
LI*lI
0*50b
0.1114
-0.10
b.5
MI1151
0.1011
0.074
O*bIb
bsb
"I*),
0.355
0.235
-0.231
be5
HIIlbl
0.1115
0.052
0.442
5 -I
*I511
0.179
-0.015
b.5
~IIIZI
- O . L I ~ ~
0.115
0,1111
11-b
11521
0.369
0,355 0.1b11
.0.209
b.5
nl2lll
-O.b9*
OIIOI
0.2111
5.7
"ILII
0.12.
0.151
-0.Ilb
5.1
nI2IYI
-0.b97
0.263
0,471
5.5
HIbZI
01141
0.11IY
-0.016
5, I
*I2151
.0.*86
0,158
0,581
5.1
-0.271
'1. I
MIJII
0,0119
4.1
*IIIZI
.o.229
0.1111
0.135
11.11
~ 1 2 1 b I
O l l l O
0.1151
rlII3I
-01*5b
0.IVI
5.b
Ul222l
0,011
Q.UOb
0.211
11,8
311l"l
-3.534
0.10Y OaOb5
0.11211
be0
~I221I
0,052
0.520
0.1311
b.1
I-III~I
-0,385
OaOb4
0.513
5..
0159V
0*yb7
b.2
-0115b
0.101
c.51n
11.b
~12211l ~12251
-0,lbO
I l l l b I
-0~119
0.5bb
0.1177
b.1
rrll22l
0,291
0.1IO
o.zon
4.9
*IZZbI
-0.41I
0.'151
0.153
5. I
"I1211
0.*51
-0.009
0.121
5.8
ul2lzl
-0,102
0.4u7
0.079
b.1
~(IZ*I
O.Jb2
-0.122
0*079
be4
~lZJ3l
-0.3b8
0.52)
-011'5
8.2
rl125l
0.11C
-0,IIb
0.121
7.b
-1z1qi
-0.3~8
0.*3*
-0.32'i
7.9
CIlZbI
-0,055
0.002
0.20P
5.7
*I2151
-0.273
0.103
-0.215
7.0
*IIIZI
-0.037
o.znn
0.4*5
*.n
HI23bl
-01201
0I258
-0.0bI
5.6
The hydrogen atoms are numbered according to the carbon atoms to which the) are bonded. rivatives, the platinum atoms, the alkyne carbon atoms, and their substituents (e.g., the atoms Pt, C ( l ) , C(2), C(3), and C ( 6 ) in the cyclohexyne complex), form near planar systerns (vide infra). In turn, the acetylenic carbon atoms (Le., C(1) and C(2) in both derivatives) lie very close to the plane of Pt, P( I), and P(2); the dihedral angle between the planes (Pt, C ( I ) , C(2)) and (Pt, P ( l ) , P(2)) is 4.4 Journal o f t h e American Chemical Society
/ 97:5 /
(3)' for the cyclohexyne adduct and 7.9 (3)' for the cycloheptyne analog. Similar values have been observed for the corresponding dihedral angle in [(CsHsC= CC02CH2CH3)Pt(P(C6H5)~)2](5.2') and [(P-N02C6H4C E C C ~ ~ C H ~ C H , ) P ~ ( P ( C ~(9.1°),5 H S ) ~ ~and ~ ] also for the platinum(0)-olefin derivatives [(tetracyanoethyleneb Pt(P(C6H5)3)2] (8.3°),'6317 and [(C12C=CC12)Pt(P(C6-
March 5, 1975
1055 Table V. Fractional Atomic Positional and Thermal Parameters for [(cycloheptyne)Pt{P(GH&] (a) Refined Positional and Anisotropic Thermal Parameters 4lOM
I
1
I
eElAl1
et1122
”LlA33
0ClAl2
EElil3
iLlA23
P I
P I 11
PI21
C l l l
Cl2l (131 CI*l
CIS1 Clbl CI7I C I I I I I
ClIl21 C I I I I I C I I I 9 l
Clll5l
CIIlbl C I I l I I
CII22l Cll23l Cll2“l Cl1251 CI12bI C I I I I I ClI32I L11331 Cl1391
c11351
CII1bl
CI2III c12121 C1213l CIZI41 C1215l CI2lbl CI221) c11221 CI2211
Cl2l“l c12251 CI22bI CI23II (12321 C1233I Cl23Yl C12351 C1230
(b) Calculated Hydrogen Atom Coordinates and Fixed Isotropic Thermal Parametersa a
41011
I
-0.321 -0
9
1b 2
I
UlA..21
AlOH
a
I
2
Er4.*21
0.053
-0.059
4.9
0.227
0.10b
-0.II2
4.6
0.032
-0.OBb
*.9
0.977
0.L81
-O*I’4b
5.9
-0.03b
6.2
-0.373
-0.015
-0,ObZ
7.8
0.bP5
0.l39
-0,161
-0.028
0.000
7.0
O.bb5
0.091
0.108
0 005
0.115
8.7
0.1110
0.09b
0.191
’4.2
-0.320
-0.0’4b
o.osn
8.7
-0.020
0.120
0.319
5.1
-0.100
-0.029
0.276
I.*
-0.111
0.135
O.’4EV
b.3
-0.041
-0.037
0.212
7.9
0,07b
Oll20
0.682
5.0
0.331
5.9
0.358
0.098
0.725
5.9
-0.35*
5.4
0.070
0.013
-0. I I I
0.03b
0.309
5,s
0.1151
O.OV1
0.572
4.1
-0.075
0. I 7 P
0.195
5.4
0.581
0.1311
0.295
Y.5
0.2’48
0.205
l.b
0.73s
0.198
0.331
(1.2
0.073
0*301
0.201
7.7
O.bb1
0.259
O.*1P
b.5
0.291
0.208
0.191
7.b
0.925
0.298
0.9b7
6.1
0.330
0.219
0.079
5.5
0.268
0.185
0.Y31
’4.b
-0.021
0.080
-0.IIP
*.5
Oeb’43
0.103
O.*VY
*.I
-0.251
0.090
-0.311
5.9
0.892
0.0’40
0.511b
‘4.V
-0.390
0.153
-0.188
5.5
0.7b3
-0.017
0.452
5.1
-0.311
0.21LI
-0.277
5.0
0.983
-0.027
0.307
5.2
-0.081
0.213
-0.085
*.I
0,283
0.029
0.252
11.1
-0.1
io
The hydrogen atoms are numbered according to the carbon atoms to which they are bonded. H5)3)2] ( 1 2 . 3 O ) . I 8 Energy minimization calculations for the complexes [ ( C H ~ C E C C H ~ ) P ~ ( P H ~ ) and ~] [(CH2=CH2)Pt(PH3)2] have shown that there is a single energy minimum when the alkyne or alkene bond lies in the Robertson, Whimp
/
plane of the platinum and phosphorus atom^.'^,^^ In contrast, in the platinum(I1) (ds) alkyne and alkene derivatives, the corresponding dihedral angle is close to 90°.2’ In terms of the Dewar-Chatt-Duncanson mode122s23for
Stable Platinum ( 0 ) Complexes of Cyclohexyne and Cycloheptyne
1056 Comparison of Important Bond Distances and Interbond Angles for [(cyclohexyne)Pt{P(CBH&}~] and [(cycloheptyne)Pt{P(C6Hd3 \ 2 1 (a) Bond Distances, A [(cyclohexyne)[(cycloheptyneb
platinum(0)-alkyne bonding, the r-bond from the platinum atom to the acetylene will be strong, while the cr-bond in the reverse direction will be weak. This will lead to a significant increase in electron density in the acetylene px* (antibonding) orbitals, and a concomitant decrease in the alkyne bond strength. The decrease in acetylene bond strength is indicated not only by the lowering of the CFC stretching frequency (1721 cm-I for the cyclohexyne adduct; 1770 cm-' for the cycloheptyne analog; c j 2200 cm-' (approximately) for free acetylene^),?,^^ but also by the increased carbon-carbon distance. Thus, the distances C ( 1)-C(2) (1.297 (8) A for the cyclohexyne complex, 1.283 (5) A for the cyclopheptyne derivative) are equal within experimental error (3.00), and are intermediate between the values normally expected for simple carbon-carbon triple (1.202 (5) A)2sa and double (1.335 (5) A)2sb bonds. Similar bond lengthening has been observeds for the coordinated acyclic acetylenes C6HsC=CC02CH2CH3 (1.286 (8) A) and pN02C6H4C=CC02CH2CH3 (1.3 13 (7) A). We note that the Pt(0)-alkyne interactions are appreciably more energetic than those in the Pt(I1)-alkyne series. For the divalent species, the C=C distance is much shorter, e.g., for [(CH3)(CH3C=CCH3)Pt(P(CH3)2(C6H5))21PFsthe distance is 1.22 (3) A,21reflecting the expected enhancement, in the Pt(0) complexes, of the acetylene px* orbital charge density. The Pt-C distances in the two complexes range from 2.034 (6) to 2.064 (4) A. Although this range exceeds the limits of statistical significance, there is no obvious electronic rationale for these differences, and the apparent distortion is most probably a consequence of crystal packing effects. The observed Pt-C distances in the present complexes are in excellent agreement with those found for [(C6HsC~CC6H5)Pt(P(c6Hs)3~2] (2.01 and 2.06 A).26As expected, the C-Pt-C angles are ca. 40' (C(1)-Pt-C(2): 37.1 (I)' for the cyclohexyne complex, 36.5 (1)' for the cycloheptyne analog), and are in good agreement with the corresponding angle in [ ( C ~ H ~ C = C C ~ H S ) P ~ ( P ( C , ~ H ~ ) ~ ] ~ ] (39°).26 These angles are, in turn, only slightly less than those found for Pt(0)-olefin complexes, e.g., 41.5" for [ (tetracyanoethylene)Pt(P(C6Hs)3)2]16,1 and 47' for [(C12C=CC12)Pt(P(C6Hs)3)21. I Consistent with increased electron density in the alkyne px* orbitals, the mean deformation (from 180') of the internal C-C-C angles for the coordinated cyclic acetylenes (52.7' for the cyclohexyne complex, 41.3' for the cyclopheptyne analog) is, in each case, some 12-16' in excess of that calculated for the hypothetical free ligands (40' for free cyclohexyne, 25' for free c y ~ l o h e p t y n e ) .A~ ~similar result has been found for the cyclooctyne complex [(cy-
Table VI.
Atoms
Pt {P(C6H:),
Pt--P( 1) Pt-P(2) Pt-C(1) Pt-C(2) P(l )-C(111) P(I)-C(121) P( l)-C(131) P(2)-C(211) P(2)-C( 221) P( 2)-C( 23 1) C( 1)-C( 2) C(1)-C(6) C(1)-C(7) C(2)-C(3) C(3)-C(4) C(4)-C(5) C( 5)-C( 6) C(6)-C( 71
Pt{P(CsHi)a\ 2 ]
2.264(1) 2.271 (1) 2.034 (6) 2.044 ( 5 ) 1 ,829 (5) 1.832 ( 5 ) 1 ,816 ( 5 ) 1.834 ( 5 ) 1 ,832 ( 5 ) 1.827 (6) 1 ,297 (8) 1 ,480 (9)
2.264 (1) 2.270 (1) 2.035 (4) 2.064 (4) 1.825 (4) 1.836 (3) 1.825 (4) 1.841 (4) 1 ,842 (4) 1 ,835 (4) 1 ,283 ( 5 ) 1 ,476 (6) 1.485 (6) 1.536 (7) 1,448 (8) 1 ,445 (9) 1.492 (7)
1 ,499 (8) 1.530 (10) 1.500 (11) 1.535 (10) (b) Interbond Angles, Degrees
[(cyclohexyne)-
[(cycloheptyne)-
Atoms
Pt { P(CeH5)3}21
Pt { P(C6H& ) 21
P( l)-Pt-P(2) P(l)-Pt-C( 1) P( 1)-Pt-C( 2) P(2)-Pt-C( 1) P(2)-Pt-C(2) C(1)-Pt- C(2) Pt-P(l)-C(I 11) Pt-P(l)-C(121) Pt- P( l)-C(13 1) C(1 ll)-P(l)-C(l21) C(11l)-P(l)-C(131) C(l21)-P(l)-C(l31 j Pt-P(2)-C(211) Pt-P(2)-C(221) Pt-P(2)-C(231) C(21 l)-P(2)-C(221) C(21 1)-P( 2)--C(231) C(221)-P(2)-C(231) Pt-C( l)-C(2) Pt-C(2)-C( 1) C( 1)-C(2)-C(3) C(2)-C( 1)-C(6) C(2)-C( 1)-c(7) c(2)4(3)-C(4) C(3)-C(4)-C( 5 ) C(4)-C( 5)-C(6) C( 1)-C(6)-C(5) C( 5)-C(6)-C(7) C( l)-C(7)-C(6)
109.54 (5) 146.6 (2) 109.7 (2) 103.6 (2) 140.7 (2) 37.1 (2) 120.1 (2) 114.3 (2) 112.7 (2) 102.2 (2) 103.2 (2) 102.2 (2) 123.5 (2) 112.7 (2) 110.2 (2) 100.9 (2) 102.9 (2) 104.7 (2) 71.9 (4) 71 . O (4) 126.4 (5) 128.1 (6)
Table VII.
102.58 (3) 153.2 (1) 117.0 (1) 104.2 (1) 140.2 (1) 36.5 (1) 114.1 (1) 115.9 (1) 117.2 (1) 100.4 (2) 105.9 (2) 101.2 (2) 113.9 (1) 123.2(1) 110.6 i i j 100.1 (2) 103.9 (2) 102.8 (2) 7 3 . 0 (2) 70.6 (2) 136.4 (4)
*
141 . 4 (4) 111.4 (4) 122 0 ( 5 ) 125.5 ( 5 )
106.7 ( 5 ) 115.9 (6) 114.4 (6) 106.5 ( 5 )
121 .c' ( 5 ) 112.3 (4)
Bond Lengths (A) and Interbond Angles (deg) in the Phenyl Rings of [(cyclohexqne)Pt(P(C6H;.)3\?] n]
P(m)-C(m,z 1) C(mnl)-C(mn2) C(mn2)-C(m/13) C(mn3)-C(m~z4) C(mn4)-C(mn5) C(m~5)-C(m/16) C(m176)-C(m111)
=
1, 12
=
1
=
=
1,
=
=
2
m
1
P(m)-C(nzul)-C(m112) 118,3 (4) P ( ~ ) - C ( ~ P I ~ ) - C ( I W Z123.1 ~ ) (4) C(~/I~)-C(PI/I~)-C(WZ/I~) 118.6 (5) C(mnl)-C(mn2)-C(m1~3) 121 . O (6) C(m~l2)-C(mn3)-C(mrz4) 120.3 (7) C ( ~ H ~ ) - C ( P I I I ~ ) - C ( ~119,7 / Z ~ ) (6) C(mt~4)-C(mnS)-C(t~16) 120.9 (6) C(m~S)-C(m/~6)-C(mnl) 119.4 (6)
m
=
1,
12 =
2
118.7 (4) 123.1 ( 5 ) 118.2(6) 119.9 (6) 121.4 (7) 119.2 (7) 120.5 (8) 120.9 (7)
Journal of the American Chemical Society
=
1,
/I =
3
Ill =
/ 97.5 /
m
=
1, 12
=
117.3 (4) 123.7 ( 5 ) 119.0 ( 5 ) 115.8 (6) 124.5 (7) 1'19.1 (7) 120.1 (7) 121 .0 (6)
March 5'. I975
2,
If =
1
n7 = 2>/ I = 2
I ,834 ( 5 ) 1.373 (8) 1,393 (9) 1.396 (10) 1.385 (9) 1.376 (9) 1.397 (8)
1.816 ( 5 ) 1.438 (8) 1.386 (9) 1.354 (1 1) 1.363 (12) 1.390 (10) 1.388 (8)
1.832 ( 5 ) 1 ,397 (8) 1.378 (9) 1.373 (10) 1,362 (1 1) 1.386 (10) 1.384 (8)
1,829 ( 5 ) 1,379 (8) 1 ,372 (9) 1.384 (11) 1.367 (10) 1.384 (9) 1.412 (8) m
1, 12
3
tt1
=
2,
II =
124.0 (4) 117.6(4) 118.3 ( 5 ) 122.4 (6) ll8.0(6) 120.3 (6) 120.2(6) 120.7 ( 5 )
m
=
2,
IT =
119.2(5) 122 5 (4) 118.3 ( 5 ) 120.5 (6) 119.4 (7) 120.7 (6) 120.2 (6) 120.8 (6)
2, / I
=
3
1 ,827 (6) 1 387 (9) 1.305(11) 1.351 (12) 1.369 (13) 1.423 (10) 1.380 (9)
1.832 ( 5 ) 1 ,392 (9) 1 392 (9) 1.378 (11) 1 .366 (12) 1.374 (9) 1,394 (9) 1
/?7 =
2
117 =
2.
11 =
123.1 ( 5 ) 117.4 ( 5 ) 119.5 (6) 119.6 (7) 121.1 (8) 120.1 (8) 120.0 (7) 119.5 (7)
3
1057 Table VIII. Bond Lengths
(A) and Interbond Angles (deg) in the Phenyl Rings of [(cycloheptyne)Pt(P(CsH,)5)2] m = l,n
m
1
nz
=
1,rz
=
1
m
115.3 (3) 125.3 (3) 119.4 (4) 120.2 (5) 119.8 (5) 120.6 ( 5 ) 120.3 (5) 119.6 (4)
P(m)-C(mn 1)-C(mn2) P(m)-C(mn1 )-C(mn6) C(mn2)-C(mnl)-C(mn6) C(m/il )-C(mu2)-C(mr13) C(mn2)-C(mn3)-C(mn4) C(mi13)-C(mii4)-C(rnn5) C(mn4)-C(rnnS)-C( mr26) C(mn5)-C(mn6)-C(mnl)
=
1,n
=
2
=
m = I,n = 3
m
1 ,825 (4) 1.395 (6) 1.373 (7) 1.375 (7) 1.390 (7) 1 ,402 (6) 1.384 (5)
1 ,836 (3) 1.384 (5) 1.393 (6) 1,367 (7) 1.373 (6) 1 ,404 (6) I , 384 (5)
1.825 (4) 1.392 (6) 1 ,396 (7) 1.371 (8) 1,367 (9) 1 ,406 (7) 1.382 (6)
P(m)-C(mn1) C(rnnl)-C(mn2) C(mn2)-C(mn3) C(mr23)-C(rnn4) C(mn4)-C(mn5) C(mn5)-C(mn6) C(mnh)-C(mnl )
Table IX.
=
1,n = 2
116.6 (3) 124.7 (3) 118.7 (3) 120.5 (4) 120.4 (4) 120.2 (4) 119.7 (4) 120.5 (3)
m = l,n
=
m
2 , =~ 1
1.841 (4) 1 ,395 (6) 1.388 (7) 1 ,364 (7) 1,381 (8) 1 ,369 (6) 1.383 (5)
=
3
m
=
2,/2
2,12 = 2
m
=
1
ni =
2.
= 2
II
=
2,11
=
3
1 ,835 (2)
1 ,842 (4) 1.381 (6) 1 393 (6) 1 371 (7) 1.371 (8) 1 ,374 (6) 1.395 (5)
118.7 (3) 1 2 3 . 1 (3) ll8.0(3) 119.8 (4) 121 .o ( 5 ) 119.5 ( 5 ) 119.8 (4) 121.8 (4)
123.1 (3) 118.2(3) 118.8 (4) 120.7 (4) 120.2 (5) 120.7 ( 5 ) 118.6 (4) 120.9 (4)
=
1 ,398 (5) 1.383 (6) 1.379 (6) 1.386 (6) 1.401 (6) 1.394 (5)
m
121.1 120.8 118.0 121 1 119.7 119 8 120.7 120.6
=
2,n
=
3
123.6 (3) 117.8 (3) 118.6 (3) 120.8 (4) 120.7 (4) 119.4 (4) 120.4 (4) 120.1 (4)
Least-Squares Planes (a) Best Weighted Least-Squares Planes Atoms defining plane
Plane5
I- 1 1-2 I- 3 1-4 I-5 1-6 1-7 11-2 11-3 11-4 11-5
11-6 11-7 11-8
Atom
+ + + +
+ + + + + + + +
+ + +
+ + + +
-0.5583X - 0.4447Y - 0.70042 3.6353 = 0 -0.5325X - 0.3929 Y - 0,74982 3.4334 = 0 0.2172X - 0.9382Y - 0 . 2 6 9 6 2 3.0205 = 0 -0.1534X 0.3105Y - 0.93812 1.9203 = 0 0.8832X 0.1893Y - 0.42912 - 0.2627 = 0 0.0863X - 0.9437Y - 0.31922 6.2331 = 0 -0.1767X 0.5692Y -- 0.80302 - 1.9987 = 0 0.9407X 0.0865Y - 0.32812 0.5121 = 0 0.7818X - 0.5860Y - 0.21292 2.3253 = 0 0.7996X - 0.5971 Y - 0.06412 2.0765 = 0 -0.2622X+ 0.2296Y - 0,93732 - 0.1597 = 0 0.9041X 0.1927Y - 0.38132 - 1.4909 = 0 -0.168OX - 0.7062Y - 0.68782 3.9339 = 0 -0.277OX 0.9520Y - 0.13042 4.0707 = 0 -0.2589X+ 0.3313Y - 0.90732 2.6430 = 0 0.6575X 0.2947Y - 0.69342 1.0448 = 0
Pt, P(lh P(2) C(1), C(2), C(3), C(6) Phenyl ring C( 111)-C( 116) Phenyl ring C(121)-C(126) Phenyl ring C(131)-C(136) Phenyl ring C(211)-C(216) Phenyl ring C(221)-C(226) Phenyl ring C(231)-C(236) Pt. P(l), P(2) C(1). C(2), C(3). C(7) Phenyl ring C(lll)-C(116) Phenyl ring C(121)-C(126) Phenyl ring C(131)-C(136) Phenyl ring C(211)-C(216) Phenyl ring C(221)-C(226) Phenyl ring C(231)-C(236)
1-8 11-1
Equationb
(b) Distances (A) of Atoms from Best Planes Plane 11-1 Atom
Plane 1-1 0.0000 (2) 0.000 (1) 0.000 (1) -0.140 (6) -0.069 (6) -0.109 (7) -0.243 (7)
0.0000 (2) 0.000 (1) 0.000 (1) -0.031 (4) 0.142 (4) 0.337 (5)
C(mn1) C(mn2) C(mri3) C(n7r14) C(nm5) C(mn6) P(m) Atom C(mr11) C(m122) C(m~3) C(mr14) C(mf25) C(mn6) P(m)
m
Plane 1-3 = 1,ri = 1
0,002 (5) -0.006 (6) 0.005 (7) 0.001 (7) -0.005 (7) 0.002 (6) 0.015 (1) m
Plane 11-3 = 1,rr = 1
0.009 (8) -0.008 (4) 0.004 (5)
Plane 1-5 m=l,r?=3
Plane 1-6 m=2,n=l
m
-0.001 (5) 0,004 (7) -0.005 (7) 0.003 (8) 0.002 (9) -0.002 (8) -0.023 (1)
-0.017 (6) 0.033 (6) -0.027 (8) -0.007 (8) 0.025 (9) -0.001 (7) -0.141 (1)
0.001 ( 5 ) 0.000 (6) -0.005 (7) 0.007 (7) -0.005 (6) 0.000 (6) 0.041 (1)
-0.008 ( 5 ) 0.002 (6) 0.009 (7) -0.009 (7) -0.004 (7) 0.012 (6) -0.002 (1)
-0.003 (6) 0.004 (9) -0.007 (10) 0.011 (9) -0.013 (8) 0.009 (7) 0.001 (1)
Plane 11-7
Plane 11-8 m = 2.rr = 3
Plane 11-4 =
1.
12 =
2
m
-0.002 (4) 0.003 (5) -0.007 (6) 0.007 (5) -0.005 ( 5 ) 0.003 (5) -0.032 (1)
Plane 11-5 = 1, 11 = 3 -0.013 (4) 0,007 (4) 0.007 (5) -0,011 (5) -0.004 ( 5 ) 0.014 (3) -0.055 (1)
m
Plane 11-6 = 2.ri = 1 -0.006 (4) 0.010 (5) -0.006 (6) -0.003 (5) 0.004 ( 5 ) 0.001 (4) -0.155 ( I )
Plane 1-7 = 2.12 = 2
-0.005 (6) -0.0037 (2) -0.198 (1) 0.311 (1) 0.391 (7) -0.045 (7) 0.368 (7)
Plane 1-4 m = l , n = 2
m
0.016 (3) -0.017 (5) -0.008 (6) 0.023 ( 5 ) -0.009 ( 5 ) -0.016 (4) 0.169 (1)
Plane 11-2
-0.0127 (2) -0.180 (1) 0.004 (1) 0.276 (7) -0.363 (8)
-0.194 (6)
Atom
Plane 1-2 -0.006 (6) 0.006 (6) -0.003 (7) 0.003 (7)
m = 2,1r = 2
-0.008 (3) 0.006 (4) 0.007 ( 5 ) -0.014 (5) 0.006 ( 5 ) 0.007 (4) 0.068 (1)
m
Plane 1-8 = 2,11 = 3
-0.004 (4) -0.001 (4) 0.002 ( 5 )
0.004 ( 5 ) -0.011 (5) 0,010 (4) -0.054 ( I )
a Planes numbered I-ti ( 1 1 = 1-8) refer to [(cy~lohexyne)PtfP(C,H~),}~]; those numbered II-JI( 1 1 = 1-8) refer to the cycloheptyne derivative. The equations of the planes, L X M Y NZ D = 0, refer to orthogonal coordinates: for [(cycloliexyne)Pt{ P(C6H;) I } 21 X = 9 . 8 7 4 7 ~i3.6844.~ 1.63312. Y = 0.0.~ 17.76283; - 0.33772. Z = 0 . 0 ~ f 0 . 0 ~ 9.9421~;for [(cycloheptyne)Pt/(PCeH-,)?j?] X = 8.9153.~ 0 . 0 ~ - 5 . 3 7 7 0 ~ ,Y = 0 . 0 . ~ + 3 3 . 5 2 2 8 ~ ~ + 0 . 0 ~ . Z = 0 . 0 ~ + 0 . 0 . ~ + 1 1 . 9 4 0 7 ~ .
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+
+
+
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Robertson, Whimp
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Stable Platinum ( 0 ) Complexes of Cyclohexyne and Cycloheptyne
1058 Table X. Torsion Angles in the Cyclic Acetylene Rings --Torsion angle, degrees5-[(cyclohexyne)-[(cycloheptyne)Atom 1 Atom 2 Atom 3 Atom 4 Pt ( P(CGH&121 Pt {P(C6HJ31 2 1 C(1) C(2) C(3)
C(2) C(2) C(3)
C(3) C(3)
C(4)
-11.9 (9)
C(4)
C(4)
C(5)
C(5) C(6)
38.4 (9) -57.2(9)
C(5) C(5) C(6) C(6) (37)
C(6) (36) C(7) C(1)
C(1) C(1) C(2)
C(6)
C(7) C(1) C(2) C(3) (74) C(4)
(35) C(5)
C(7)
1.6(10)
40.9 (8) -15.4(9)
- 3 . 3 (11) -13.9(8)
37.4 (7) -67.2(8) 65.9 (9) -36.8 (9)
C(1) C(2) 17.9 (9) C(6) The sign of the torsion angle is positive if, when looking from atom 2 to atom 3, a clockwise rotation of atom 1 would superimpose it on atom 4.
(109.84') and ~ N O ~ C ~ H ~ C S C C ~ ~(103.42'), CH~CH~ we suggest that the apparent anomaly is steric in origin, arising from differing crystal packing effects. The P-C distances average 1.828 8, for the cyclohexyne adduct and 1.834 8, for the cycloheptyne analog. These values are in excellent agreement with those observed for numerous coordinated triphenylphosphine groups and also for free triphenylphosphine where the average P-C distance is 1.828 The angles a t the phosphorus atoms show the customary deformations from regular tetrahedral values, with the Pt-P-C angles being significantly greater and the C-P-C angles being significantly less than 109' 27'. The phenyl carbon-carbon distances average 1.384 A for the cyclohexyne derivative and 1.385 A for the cycloheptyne complex. This apparent contraction relative to the benzene value (1.397 A) results from a progressive shortening of the C-C distances toward the ring extremities and is characteristic of libration shortening. Deviations of the internal phenyl ring angles from 120' (particularly the angle C(mn2)C(mn1)-C(mn6)) are, likewise, characteristic of joint libration effects and electronegativity differences between Pand H-bonded carbon atoms.30
where the deformation of the CEC-C angle in the coordinated alkyne is 34°;4 cJ a n estimated 15' for free c y c l ~ o c t y n e , .For ~ ~ the diphenylacetylene complex,26 the corresponding deformation is 40'. There is, clearly, very little accumulated ring strain in the coordinated cyclohexyne moiety. The C-C-C angles are all Acknowledgments. W e thank Drs. M. A. Bennett and T. within 6' of the regular tetrahedral value, and the distances Yoshida of this school for samples of both cyclic alkyne deC(3)-C(4), C(4)-C(5), and C(5)-C(6) are within 3.50 of rivatives. W e are grateful for generous allocations of time the value normally expected for carbon-carbon single bonds on the IBM 360/50 and Univac-1108 computers of The (1.537 (5) A).25bIn contrast, the coordinated cycloheptyne Australian National University Computer Centre. group appears to be quite severely strained. The internal angles a t C(4), C(5), and C(6) each differ substantially (by Supplementary Material Available. A listing of structure factor 1 1 - 16') from the tetrahedral value. In addition, the disamplitudes will appear following these pages in the microfilm editances C(4)-C(5) and C(5)-C(6) (1.448 (8) and 1.445 (8) tion of this volume of the journal. Photocopies of the supplementaA, respectively) have apparently undergone substantial ry material from this paper only or microfiche (105 X 148 mm, com ression. To a lesser extent, the bond C(6)-C(7) (1.492 24X reduction, negatives) containing all of the supplementary ma(7) ) also appears to be compressed. terial for the papers in this issue may be obtained from the Journals Department, American Chemical Society, 1155 16th St., The bonds adjacent to the alkyne linkage (C(l)-C(6) N.W., Washington, D.C. 20036. Remit check or money order for (1.480 (9)), C(2)-C(3) (1.499 (8)) for cyclohexyne; C(1)$7.00 for photocopy or $2.00 for microfiche, referring to code C(7) (1.476 (6)), C(2)-C(3) (1.485 (6) A) for cyclonumber JACS-75-1051. heptyne) appear uniformly longer than those commonly observed in acyclic acetylenes (1.459 (5) A),25cbut they do References and Notes not differ significantly from the expected value (ca. 1.471.48 A) for bonds between sp (tending toward sp2) and sp3 A:Krebs in "Chemistry of Acetylenes,'' H. G. Viehe. Ed.. Marcel Dekker, New York, N.Y., 1969, Chapter 15. hybridized carbon atoms.28 M. A. Bennett, G. B. Robertson, P. 0. Whimp. and T. Yoshida, J. Amer. The atoms C(l), C(2), C(3), and C(6) of the coordinated Chem. SOC.,93,3797 (1971). G. B. Robertson and P. 0. Whimp. J. Organometal. Chem., 32, C69 cyclohexyne group are planar within experimental error, (1971). the maximum deviation from this plane being -0.006 (6) A G. B. Robertson and P. 0. Whimp, unpublished results. a t C(1). The platinum atom is -0.0127 (2) A from this M. A. Bennett, G. B. Robertson, J. M. Rosalky. and P. 0. Whimp, unpublished results. plane, while C(4) and C(5) are respectively 0.276 (7) and The Busing and Levy programs for four-circle diffractometers (Acta -0.363 (8) 8, from this plane. Crystallogr., 22, 457 (1967)), were used for all phases of diffractometer control and data collection. Similarly, in the cycloheptyne complex, C( l ) , C(2), W. R. Busing and H.A. Levy, J. Chem. Phys., 26,563 (1957). C(3), and C(7) are planar within experimental error; the P. W. R. Corfield, R. J. Doedens, and J. A. Ibers, horg. Chem., 6, 197 maximum deviation from the plane is 0.009 (4) 8, (C(1)). (1967). C. T. Prewitt, Ph.D. Thesis, Massachusetts Institute of Technology, The platinum atom is only -0.0037 (2) 8, from this plane, 1962, p 163. The formulas used to calculate the dispersion-corrected while C(4) and C(6) are respectively 0.391 (7) and 0.369 real and imaginary parts of the structure factor (neglecting temperature factors) are (7) 8, above the plane and C(5) is 0.045 (7) A below the plane. The cycloheptyne ring has, therefore, a distorted A = 1 ( ( i , ,- 4 f ' ) cos rn - ~ . is"i n 6; chair conformation. atoms I The Pt-P distances average 2.267 A, and range from B = C { ( i o ~ f ' sin ) 6 + Ai" c o s n ! 2.264 (1) to 2.271 (1) 8,. Values of 2.28 and 2.27 A were atom3 found for the Pt-P distances in the diphenylacetylene derivwhere 6 = 2 n ( h r + /?Y + 1 2 ) ative.2h In all three examples, however, the observed Pt-P (10) D. T. Cromer, Acta Crystallogr., 18, 17 (1965). distances are very much shorter than the value of 2.49 A ( 1 1) "International Tables for X-Ray Crystallography." Vol. 111, Kynoch Press, Birmingham, England, 1962, p 202. calculated from the sum of the appropriate covalent radii R. F. Stewart, E. R. Davidson, and W. T. Simpson, J. Chem. Phys.. 42, for simple u-bonds. The angle P(1)-Pt-P(2) for the cyclo- (12) 3175 (1965). hexyne derivative (109.54 (5)') is larger than the corre- (13) G. B. Robertson and P. 0. Whimp, horg. Chem., 13, 1047 (1974). (14) C. K. Johnson, Report ORNL-3794, Oak Ridge National Laboratory, Oak sponding angles in the cycloheptyne analog (102.58 (3)') or Ridge, Tenn.. 1965. the diphenylacetylene derivative ( 102°).26I t is unlikely that (15) The weighting method is described by D. M. Blow, Acta Crysfallogr., 13, 168 119601. this discrepancy is electronic in origin, and, as similar dif(16) C. Panaioni. G. Bombieri, U. Belluco, and W. H. Baddley, J. Amer. ferences have been observed for the P-Pt-P angles in the Chem. SOC.,90, 798 (1968). platinum(0) complexes of C ~ H S C = = C C O ~ C H ~ C(17) H ~G. Bombieri. E. Forsellini, C. Panattoni, R. Graziani, and G. Bandoli, J. ClOOCtyne)Pt{P(C6H5)312],
w
PI
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Journal of the American Chemical Society
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March 5. I975
1059 Chem. Soc. A, 1313 (1970). (18) J. N. Francis, A. McAdam, and J. A. Ibers, J. Organometal. Chem., 29, 131 (1971). (19) K. S. Wheelock, J. H. Nelson, L. C. Cusachs, and H. 5 . Jonassen, J. Amer. Chem. Soc.,92, 5110 (1970). (20) J. H. Nelson and H. B. Jonassen, Coord. Chem. Rev.. 6, 27 (1971). (21) B. W. Davies and N. C. Payne, Can. J. Chem., 51, 3477 (1973). (22) M. J. S. Dewar, Bull. SOC.Chim. Fr., 18, C 71 (1951). (23) J. Chatt and L. A. Duncanson, J. Chem. SOC.,2939 (1953).
(24) J. L. Boston. S. 0.Grim, and G. Wilkinson, J. Chem. SOC..3468 (1963). (25) (a) Chem. sdc., Spec. fubl., No. 18 S16s (1965); (b) ibid, p S14s: (c) ibid, p S15s. (26) J. 0.Glanville, J. M. Stewart, and S. 0.Grim, J. Organometal. Chem., 7, P9 (1967). (27) Reference 1, p 1006. (28) J. Dale, ref 1, pp 1-6. (29) J. J. Daly, J. Chem. SOC.,3799 (1964). (30) J. M. Guss and R. Mason, J. Chem. Soc., Dalton Trans., 2193 (1972).
Steric vs. Electronic Effects in Palladium-Thiocyanate Complexes. The Crystal Structures of Dithiocyanato[bis( dipheny lphosphino)methane]palladium( 11), Isothiocyanatothiocyanato[ 1,2-bis(diphenylphosphino)ethane]palladium( 11), and Diisothiocyanato[ 1,3-bis(diphenylphosphino)propane]palladium( 11) Gus J. Palenik,*la M. Mathew,la W. L. Steffen,lb and G . BeranlC Contribution from the Departments of Chemistry, University of Florida, Gainesville, Florida 3261 I , and University of Waterloo, Waterloo, Ontario, Canada. Received July 18, 1974
Abstract: The crystal structures of the series (C6H5)2P(CH2)nP(C6H5)2Pd(cNs)~, CNS represents the thiocyanate ion without specifying the mode of attachment ( n = 1-3), have been determined by X-ray diffraction tethniques. The most important observation is that the thiocyanate coordination changes from S,S when n = 1 to S,N for n = 2 and N,N with n = 3. The conclusion is that the mode of thiocyanate coordination in palladium thiocyanate-phosphine complexes is determined by are ~ monoclinic, P ~ ( S C ~space ) ~ group P21/n, steric rather than electronic effects. The crystals of ( C ~ H S ) ~ P C H ~ P ( C ~ H ~ ) with a = 10.426 (8) A, b = 29,353 (10) A, c = 9.884 (6) A, and 13 = 119.86 (4)O. The final R value for the 2814 reflections crystallizes with the orthorhombic used in the analysis was 0.039. The complex (C~HS)P(CH~)~P(C~H~)P~(SCN)(NC~) space group P212121. The cell dimensions are a = 17.773 (6), b = 23.212 (15), and c = 8.502 (4) A. A total of 2249 reflections was used in the analysis and the final R value was 0.056. The last compound (C6H5)2P(CH2),P(C6Hs)2Pd(NCS)2is monoclinic with the space group 12/a and cell dimensions of a = 14.774 (6) A, b = 9.181 (5) A, c = 21.182 (10) A, and /3 = 95.48 (2)O. The molecule has twofold symmetry, as required for four molecules per unit cell. The final R value for the 1781 reflections used in the analysis was 0.025. The Pd-P bond distances are a function of the nature of the trans atom. a u-bond rather than a n-bond effect. The Pd-S distances appear to be independent of the tip of the thiocyanate ion from the coordination plane. A comparison of the angular changes in the three compounds is easily interpreted in terms of increasing steric effects with an increase in the chain length between the phosphorus atoms. The changing mode of the thiocyanate ion is explainable in terms of steric effects without invoking any *-bonding arguments.
The thiocyanate ion is an ambidentate ligand that can v ~ k e d In. ~fact ~ ~contrary ~ evidence such as nmr coupling coordinate either through the sulfur or nitrogen atom.2 This constants which suggested that 7r-bonding in Pt(n)-phosambidentate nature can be interpreted in terms of the “softphine complexes was minimal a t best” was ignored. The hard” concepts developed by P e a r ~ o n .Therefore, ~ in the presence of both N-bonded and S-bonded thiocyanates in case of class b or “soft” metals, such as Pd(I1) or Pt(II), Pd(dppn)(NCS)(SCN), dppn is ( C ~ H S ) ~ P C H ~ C H ~ C H ~ N coordination of thiocyanate is expected to occur through the (CH3)2,” appeared to support these n-bonding arguments “soft” sulfur atom. Indeed, Pd(I1) complexes with many and has also been used as an example of “antisymbiosis.”6 amine ligands form S-bonded thiocyanates. In contrast, a However, the existence of both N-and S-bonded thiocylimited number of phosphine complexes of Pd(I1) were anates in Pd(dpe)(NCS)(SCN),I3 dpe is (C6H5)2PCH*found to have N-bonded thiocyanates, a fact which has CH2P(C&s)2, suggested that steric effects were extremely been rationalized on the basis of n - b ~ n d i n g polyelectronic ,~ important and tended to refute the “antisymbiosis” arguperturbation theory,5 and the so-called antisymbiosis efments, a t least for palladium complexes. fects.6 The problem in all of the previous studies has been the A study of palladium- and platinum-thiocyanate comdifficulty in separating steric from electronic effects. Thereplexes involving PPh3, AsPh3, and SbPh3 was complicated fore, after the completion of our study of by the fact that the steric and electronic factors operated in Pd(dpe)(NCS)(SCN), we undertook an investigation of the same d i r e ~ t i o nNevertheless, .~ steric control was used to two other closely related complexes Pd(dpm)(SCN)2, dpm prepare the N-bonded complex P ~ [ ( C ~ H S ) ~ N C H ~ C isH ~( C - ~ H S ) ~ P C H ~ P ( C and ~ H ~Pd(dpp)(NCS)z. )~, dpp is N H C H ~ C H ~ N ( C ~ H(NCS)+ S ) ~ ] rather than the usual S( C ~ H S ) ~ P C H ~ C H ~ C H ~ PThe (C~ series H ~ )of~ .complexes bonded thiocyanates.8 However, despite this early evidence ( C ~ H ~ ) ~ P ( C H ~ ) , P ( C ~ H S ) ~ PC~N( C SN does S ) ~not , specthat steric effects could explain the changes in thiocyanate ify the mode of attachment, will have approximately equivcoordination, n-bonding arguments continued to be inalent electronic effects but vastly different steric requirePalenik, Mathew, Steffen, Beran
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Palladium- Thiocyanate Complexes
