A platinum cluster complex containing a triply bridging carbonyl. The

Thermodynamic and Kinetic Control over the Reduction Mechanism of the Pd3(dppm)3(CO)(I) Cluster. Frédéric Lemaître, David Brevet, Dominique Lucas, ...
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Organometallics 1986,5, 344-348

344

A Platinum Cluster Complex Containing a Triply Bridging Carbonyl: The Synthesis and Structure of (p,-Carbonyl)tris[ p-bis( diphenylphosphino)methanel- friangulo t riplatinum(2 ) Hexafluorophosphate

+

George Ferguson," la Brian R . Lloyd,lb and Richard J. Puddephatt'lb Departments of Chemistry, University of Guelph, Guelph, Ontario, Canada N l G 2W1, and University of Western Ontario, London, Ontario, Canada N6A 587 Received June 24, 1985

Reaction of [Pt(02CCFd2(dppm)], dppm = Ph2PCH2PPh,with CO in aqueous methanol gives the cluster complex [Pt3(p3-CO)(p-dppm)3][CF3C02]2 (1) which may be converted to the [PF6]-salt 2. The complexes 1 and 2 are the first complexes reported to contain the Pt3(p3-CO)group and are significant as models for CO chemisorbed at a threefold site on a Pt surface. Complexes 1 and 2 were characterized by elemental analysis, IR, and lH, 31P,and '%PtNMR and by X-ray crystallography (for 2, as the acetone solvate). Crystals of 2.C3H60 are triclinic, space group PI, with 2 = 2, a = 14.090 (2) A, b = 22.711 (4) A, c = 13.637 (4) A, cy = 103.43", = 99.52 (2)", and y = 106.72 (1)".The structure was solved by the heavy-atom method and refiied by full-matrix least-squares calculations with anisotropic thermal parameters for the non-phenyl and non-solvate atoms. At convergence,R = 0.035 for 6234 reflections with I > 3a(I). The crystal structure contains discrete cations, anions, and acetone solvate molecules. The Pt atoms of the cation form a triangle with Pt-Pt = 2.613-2.650 (1)A. The carbonyl ligand occupies a triply bridging site with Pt-C = 2.080-2.095 (9) A. The atoms of the Pt3P6 moiety are only approximately coplanar; the Pt-P distances are in the range 2.262-2.304 (2) A. The three PtzPzCfive-membered rings adopt envelope conformations with the CH2 moiety at the flap.

Introduction When carbon monoxide is adsorbed onto a Pt(ll1) surface, the on-top (terminal) sites are occupied first [v(CO) = 2110 cm-'1 but at higher coverage the twofold ( p 2 ) sites are preferred [v(CO) = 1840-1875 ~ m - ' ] . ~Recently it has been shown that threefold (p,) sites are also occupied a t high coverage [v(CO) = ca. 1810 cm-lI2 and that the energy difference between the pz-CO and p,-CO groups is only 4 ( f l ) kJ mol-'. From the analogy between surfaces and clusters,, it should therefore be possible to prepare cluster complexes containing Pt3(p3-CO)units. However, even high nuclearity clusters such as [Pt19(CO)zz]4-or [Pt30(CO),]2- contain only terminal and p2-C0 We now report the first synthesis of a complex containing the Pt3(p3-CO)group and its characterization by spectroscopic techniques and by X-ray crystallography as [Pt3( c L ~ - C O ) ( P - ~ P[PF,IY(CH,)ZCO, P~)~I dppm = Ph2PCH2PPh2.6 Results and Discussion Reaction of [Pt(O&CF,),(dppm)] with carbon monoxide a t 100 "C for 3 days in methanol-water solvent gave the complex [Pt&.~~-CO)(p-dppm),] [CF3COzI2(1) in 97 % yield. This complex was formed in spectroscopically pure form, (1) (a) University of Guelph. (b) University of Western Ontario. (2) Baro, A. M.; Ibach, H. Surf. Sci. 1981, 103, 248. Hayden, B. E.; Bradshaw, A. M. S u r f . Sci. 1983, 125, 787. (3) Muetterties, E.L.; Rhodin, T. N.; Band, E.; Brucker, C. F.; Pretzer, W.R. Chem. Rev. 1979, 79,91. (4)Clark, H. C.; Jain, V. K. Coord. Chem. Rev. 1984, 55, 151.

( 5 ) Semitriply bridging carbonyls are observed in some heteronuclear clusters. Bender, R.; Braunstein, P.; Dusausoy, Y.; Protas, J. J. Organomet. Chem. 1979, 172, C51. Bender, R.; Braunstein, P.; Jud, J. M.; Dusausoy, Y.Inorg. Chem. 1984, 23, 4489. (6) The synthesis of a related palladium complex, [Pd3(p3-CO)(pdppm)3][CF3C0,],, has been reported recently. ManojloviE-Muir, Lj.; Muir, K. W.; Lloyd, B. R.; Puddephatt, R. J. J. Chem. SOC.,Chem. Commun. 1983,1336. Lloyd, B. R.; Puddephatt, R. J. Inorg. Chim.Acta 1984, 90, L77. ManojloviE-Muir, Lj.; Muir, K. W.; Lloyd, B. R.; Puddephatt, R. J. J. Chem. SOC.,Chem. Commun. 1985, 536.

0216-7333/S6/2305-0344$01.50/0

and it was readily converted to [Pt3(p3-C0)(p-dppm),][PF612(2) by reaction in methanol with excess NH4[PF6]. Complex 2 was characterized crystallographically as its acetone solvate. Description of the Structure of 2.(CH3)&0. The structure contains discrete cations, anions and loosely entrapped acetone of solvation separated by normal distances. In the cation (Figure 1)the Pt atoms form a triangle with Pt-Pt distances 2.613 (l), 2.638 (l), and 2.650 (1)A and Pt-Pt-Pt angles 59.23 (11, 60.17 (l), and 60.60 (1)"(see Table I). The carbonyl ligand occupies a triply bridging site, with Pt-C distances 2.080 (9), 2.089 (E!), and 2.095 (9) 8, and Pt-C-Pt angles 77.6-78.8(3)". The Pt3P6 atoms are only approximately coplanar (the deviation of the P atoms from the P&plane are as follows: P11,-0.276 (2); P12, -0.013 (2); P21, -0.619 (2); P22, 0.154 (2); P31, -0.495 (2); P32, -0.069 (2) A). The Pt-P distances are in the range 2.262 (2) to 2.304 (2) A with a mean value of 2.282 A. All three Pt2P2Crings adopt envelope conformations with the methylene carbon a t the flap; two of the atoms, C(2) and C(3), are folded toward the bridging carbonyl and the other, C(4), is folded away. Presumably these conformational variations improve the packing of the ions. In the related palladium complex [Pd,(p,-CO) ( p dppm),] [CF3CO2I2,the corresponding Pd-Pd, Pd-C, and Pd-P distances are 2.576 (1)-2.610 (2) A, 2.09 (1)-2.18 (l), and 2.296 (3)-2.340 (3) A, respectively.6 The structures are very similar, but, in the platinum complex, the metal-metal distances are slightly longer and the metalphosphorus and metal-carbon distances are slightly shorter than in the palladium complex. The Pt-Pt distances in 2 are slightly shorter than the range of Pt-Pt distances of 2.672 (2)-2.790(7) A found in platinum clusters such as [ P ~ , ( ~ ~ L - S O Z ) ~ [( PP~P~~(~P)-~CIO, ) ~ ( P C(CY Y ~ )=~ CI Y C ~ O hexyl), and [Pt4(p-CO)a(PMe2Ph)4]7-'o but lie in the range (7) Moody, D. C.; Ryan, R. R. Inorg. Chem. 1977,16, 1052. (8)Albinati, A,; Carturan, G.; Musco, A. Inorg. Chim. Acta 1976,16, L3.

0 1986 American Chemical Society

Organometallics, Vol. 5, No. 2, 1986 345

A Platinum Complex Containing a Triply Bridging Carbonyl

-2900

-2800

-3000 6/ppm

Figure 1. A view of the [Pt3(~-CO)(pdppm)3]2+ cation with the crystallographic numbering scheme. For clarity only the phenyl carbon bonded to each phosphorus atom is shown (phenyl ring atoms are numbered Cnl-Cn6 where n = 1-12).

of Pt-Pt bond lengths of 2.584 (2)-2.769 (1)A found for diplatinum(1) complexes."J2 These observations are consistent with the formal oxidation state for platinum of + 2 / 3 for complex 2 and with the presence of Pt-Pt single bonds in the cluster. Spectroscopic Properties of 1 and 2. The carbonyl stretching frequencies of 1 and 2 were a t 1750 and 1765 cm-', respectively, which may be compared to the value of v(C0) of 1810 cm-' for CO at a threefold site on Pt(ll1). It seems that back-bonding from platinum into a* orbitals of CO is reasonably strong despite the 2+ charge on the cluster. The v(C0) values for 1 and 2 were -70 cm-I to lower energy than those of the analogous palladium complexes; similar differences have been observed in other carbonyl complexes such as [M,Cl,(p-CO)(p-dppm),], M = Pd or Pt.13J4 The 1H(31PJNMR spectra of 1 and 2 each contained an AB quartet for the CHAHBP,protons showing that there is no plane of symmetry containing the Pt3P6C3 atoms of the Pt,(dppm), unit. This nonequivalence of the CH2P2 protons arises due to the presence of the p3-CO ligand on one side of the Pt3 triangle. The 31P(1HJNMR spectra of 1 and 2 each contained a singlet with very complex and incompletely resolved satellites due to coupling to lg6Pt,as shown in Figure 2a. The complexity arises in part from the superposition of resonances due to the Pt,P6 systems containing 0 (29% natural abundance), 1 (44%), 2 (23%), and 3 (4%) lg6Ptatoms. The spectra were insufficiently resolved to allow a full simulation, but the coupling constant lJ(PtP) was easily obtained and partial simulation of the system containing one lg5Ptcenter showed that there is one large ,J(PP) coupling of 170 Hz in 1 and 140 Hz in 2 [illustrated by i in Figure 21. This large coupling is tentatively assigned as that between the nearly trans phosphorus atoms P(ll)P(22), P(21)P(32),and P(12)P(31),defined in Figure 1. The long-range couplings V(PtP) were too small to be resolved. In the 195Pt('HJNMR spectrum (Figure 2b) the most prominent feature is the triplet arising from the isotopomer containing a single lg5Ptatom, due to coupling to the two (9) Chatt, J.; Chini, P.; Dahl, L. F.; Vranka, R. G. J. Am. Chem. SOC.

10

0

- 10

-20

6/ppm

Figure 2. NMR spectra of complex 2: (a) NMR spectrum (121.4MHz). The inset shows the lg5Ptsatellites at higher sensitivity and (i) shows the large J(PP) coupling (see the text). (b) lg5PtNMR spectrum (64.3MHz).

directly bound phosphorus atoms. Satellite spectra, arising from the isotopomer with two lg6Ptatoms, were also observed (Figure 2b) and allowed the coupling constant ' J (PtPt) = 540 Hz to be determined. The value is comparable to values found in other triangular Pt, ~ l u s t e r s . ' ~ J ~ Another feature of interest is the significant difference in the 31Pand lg6Ptchemical shifts between complexes 1 and 2. A similar effect has been observed in the analogous palladium complexes,6 and it is rationalized by assuming that in 1 a trifluoroacetate ion is weakly coordinated to platinum a t the triply bridging site, which is vacant in complex 2. Complex 1 may therefore be better characterized as [Pt3(02CCF3)(p3-CO)(p-dppm)3] [CF,CO,]. The spectroscopic data are clearly consistent with the structure of 2 being the same in solution as in the solidstate structure determined crystallographically (Figure 1). Bonding in Complex 2. The bonding in complex cation 2 can be treated in several ways. First, it can be seen that each platinum atom is in oxidation state + 2 / 3 and that, if the Pt-Pt bonds within the Pt3triangle are single twoelectron bonds, each platinum atom has a 16-electron-valence shell. Secondly, the total number of valence electrons in the cluster is 42 and polyhedral skeletal electron pair theory predicts a "latitudinal" structure with a planar PbP6 ske1et0n.l~ The theoretical work is based on a neutral Pt&6 cluster but, since the carbonyl ligand in 2 provides two electrons to make up for the 2+ charge on the cluster cation, the result is the same. In a latitudinal [Pt&]'+ cluster the LUMO is expected to be an orbital of Al yymmetry derived from a linear combination of the hybrid 6s 5d,2 orbitals directed toward the center of the Pt3triangle.17 If the CO ligand donates two electrons into this Al molecular orbital, it would be expected to occupy the symmetrical triply bridging coordination site as observed. It is possible, and only detailed MO calculations could

1969.I -91. 1574. _._. - , - - - - -

(IO) Braunstein, P.; Jud, J.-M.; Dusausoy, Y.; Fischer, J., Organometallics 1983, 2, 1980. (11) ManojloviE-Muir, Lj.; Muir, K. W.; Solomun, T. J. Organomet. Chem. 1979,179,479. (12) ManoiloviE-Muir. Li.: Muir, K. W. J. Organomet. Chem. 1981. 219, 129.

(13) Balch, A. L.; Benner, L. S. J. Am. Chem. SOC.1979, 100, 6099. (14) Brown, M. P.; Puddephatt, R. J.; Rashidi, M.; Seddon, K. R. J. Chem. Soc., Dalton Trans. 1978, 1540.

(15) Moor, A.; Pregosin, P. S.; Venanzi, L. M. Znorg. Chim.Acta 1981,

48, 153.

(16) Moor, A.;Pregosin, P. S.; Venanzi, L. M. Znorg. Chim.Acta 1981, 48,153. (17) Evans, D. G.; Mingos, D. M. P. J. Organomet. Chem. 1982,240, 321. The planarity of the Pt8L, skeleton is most simply rationalizing in terms of the isolobal analogy of PtLl and CH:, fragments, so that planar PtSL6 is isolobal with cyclopropane. Hoffmann, R. Angew. Chem., I n t . Ed. Engl. 1982, 21, 711.

346 Organometallics, Vol. 5, No. 2, 1986

Ferguson et al.

Table I. Selected Interatomic Distances and Angles atom 1 Ptl Ptl Ptl Ptl Ptl Pt2 Pt2 Pt2 Pt2 Pt3 Pt3 Pt3 P11 P11 P11 P12

atom 1 Pt2 Pt2 Pt2 Pt2 Pt3 Pt3 Pt3 P11 P11 P12 Ptl Ptl Ptl Ptl Pt3 Pt3 Pt3 P21 P21 P22 Ptl Ptl Ptl Ptl Pt2 Pt2 c3 C71 Pt3 Pt3 Pt3 c3 c3 c91 Pt3 Pt3 Pt3 c4

a. Bond Distances (A) dist atom 1 atom 2 2.638 (1) P12 C31 2.650 (1) P12 C41 2.304 (2) P21 c2 2.284 (2) P21 C51 2.095 (9) P21 C61 2.613 (1) P22 c3 2.277 (2) P22 C71 2.271 (2) P22 C81 2.089 (8) P31 c3 2.294 (2) P31 c91 2.262 (2) P31 ClOl 2.080 (9) P32 c4 1.843 (8) P32 Clll 1.807 (8) P32 c121 1.811 (8) 01 c1 1.835 (8) mean P-F = 1.570 (7) A; mean aromatic C-C = 1.38 (1)A

atom 2 Pt2 Pt3 P11 P1.2

c1

Pt3 P21 P22

c1

P31 P32

c1

c4 c11 c21 c2

atom 2 Ptl Ptl Ptl Ptl Ptl Ptl Ptl Ptl Ptl Ptl Pt2 Pt2 Pt2 Pt2 Pt2 Pt2 Pt2 Pt2 Pt2 Pt2 Pt3 Pt3 Pt3 Pt3 Pt3 Pt3 P22 P22 P31 P31 P31 P31 P31 P31 P32 P32 P32 P32

atom 3 Pt3 P11 P12

c1

P11 P12

c1

P12

c1 c1

Pt3 P21 P22

c1

P21 P22 c1 P22

c1 c1

Pt2 P31 P32

c1

P31 P32 C81 C81 c3 c91 ClOl c91 ClOl ClOl c4 Clll c121 Clll

b. Bond Angles (deg) angle atom 1 59.23 (1) Pt2 154.10 (5) P31 94.86 (5) P31 50.8 (2) P32 95.69 (5) Ptl Ptl 154.09 (6) 50.4 (2) Ptl 109.98 (8) c4 119.8 (2) c4 115.0 (2) c11 60.60 (1) Ptl Ptl 92.62 (5) Ptl 157.63 (5) c2 51.0 (2) 149.30 (6) c2 97.34 (5) C31 51.0 (2) Pt2 109.64 (8) Pt2 124.6 (2) Pt2 113.4 (2) c2 60.17 (1) c2 148.86 (5) C51 94.46 (5) Pt2 50.9 (2) Pt2 91.04 (5) Pt2 154.58 (5) c3 105.4 (4) c4 106.3 (4) Clll 108.1 (3) Ptl 114.1 (3) Ptl 120.1 (3) Ptl Pt2 104.1 (4) Pt2 104.0 (4) 104.9 (4) Pt3 110.3 (3) P12 119.2 (3) P22 110.1 (3) P11 103.3 (4)

settle this point, that the above argument is oversimplified, and it should be recognized that greater steric effects would be observed if the CO ligand adopted a p2-bridging position. However, we suggest that both steric and electronic effects probably favor the unique Pt&-CO) linkage found experimentally for complex 2.

Experimental Section Infrared spectra were recorded as Nujol mulls using a B e c k " Acculab 4 spectrometer. 'H NMR and lHI3lP}NMR spectra were recorded on a Varian XL-100 NMR spectrometer. 31Pand lg5Pt NMR spectra were recorded on a Varian XL-300 NMR spectrometer. References were Mel% ('H), (Me0)3P0 (31P),and aqueous K2[PtC1,] (lg5Pt).

atom 2 Pt3 Pt3 Pt3 Pt3 P11 P11 P11 P11 P11 P11 P12 P12 P12 P12 P12 P12 P21 P21 P21 P21 P21 P21 P22 P22 P22 P22 P32 P32

c1 c1 c1 c1 c1 c1 c2 c3 c4

dist 1.807 (8) 1.807 (8) 1.848 (8) 1.804 (8) 1.813 (8) 1.858 (8) 1.789 (8) 1.792 (8) 1.823 (8) 1.814 (8) 1.817 (8) 1.832 (8) 1.803 (8) 1.812 (8) 1.154 (9)

atom 3

c1 P32 c1 c1 c4 c11 c21 c11 c21 c21 c2 C31 C41 C31 C41 C41 c2 C51 C61 C51 C61 C61 c3 C71 C81 C71 c121 c121 Pt2 Pt3 01 Pt3 01 01 P2 1 P31 P32

angle 51.3 (2) 113.28'(8) 121.4 (2) 115.3 (2) 109.5 (3) 119.3 (3) 113.1 (3) 103.6 (4) 105.9 (4) 104.4 (4) 111.6 (3) 121.1 (3) 108.7 (3) 103.6 (4) 105.1 (4) 105.6 (4) 107.6 (3) 119.8 (3) 111.1 (3) 105.2 (4) 106.0 (4) 106.2 (4) 109.4 (3) 109.1 (3) 120.9 (3) 104.51 (4) 106.9 (4) 106.2 (4) 78.2 (3) 78.8 (3) 131.8 (6) 77.6 (3) 133.1 (7) 134.9 (7) 109.0 (4) 110.0 (4) 112.8 (4)

Preparation of [Pt(O@CF,),(dppm)]. [F'tC12(dppm)](5.131 mmol) and [Ag02CCH3](10.244 mmol) were reacted in acetone (50 mL) in the presence of excess CF3COOH (15 mL). The suspension was stirred for 0.5 h at room temperature under Nz, then heated briefly at 60 "C, and then allowed to cool for 1 h. The solution was then filtered, and the solvent was evaporated from the filtrate under vacuum to give an oil. The oil was then dissolved in acetone (5C-100 mL), and excess pentane was added to precipitate a white crystalline solid: yield 92%; mp 200-210 "C dec; 'H NMR [(CD3)2CO]6 5.00 [t, ,J(PH) = 12, 3J(PtH) = 88 Hz, CH2P2];,'P NMR [(CD3),C0] 6 -67.7 [s, 'J(PtP) = 3360 Hz]. Anal. Calcd for [Pt(CF3COJz(dppm)]: C, 43.24; H, 2.75. Found: C, 43.00; H, 2.92. Preparation of [Pt3(~3-CO)(~-d~~m)31[CF3C0212. [Pt(02CCF3)2(dppm)](1.319 mmol) and CO (4 atm) were reacted

A Platinum Complex Containing a Triply Bridging Carbonyl

atom

X

Ptl Pt2

0.00260 (2) 0.14305 (2) 0.16857 (2) 0.2588 (3) 0.7962 (3) -0.0578 (2) -0.1010 (2) 0.0809 (2) 0.2843 (2) 0.3361 (2) 0.1265 (2) 0.2142 (6) 0.3178 (6) 0.3112 (7) 0.1991 (6) 0.3543 (6) 0.1685 (6) 0.7856 (7) 0.7107 (7) 0.8106 (6) 0.8854 (7) 0.7159 (7) 0.8764 (7) 0.0087 (5) -0.0603 (6) 0.3426 (6) 0.0466 (6) -0.1077 (6) -0.0424 (7) -0.0780 (8) -0.1808 (8) -0.2478 (8) -0.2106 (7) -0.1583 (6) -0.2026 (7) -0.2773 (8) -0.3085 (8) -0.2677 (8) -0.1907 (7) -0.1186 (6) -0.1802 (7) -0.1871 (8) -0.1362 (8) -0.0781 (8) -0.0670 (7) -0.2280 (6) -0.2474 (8) -0.3417 (9) -0.4141 (9) -0.3968 (9) -0.3024 (7) 0.119 ( 7 )

Pt3 P1 P2

P11 P12 P21 P22 P31 P32 F11 F12 F13 F14 F15 F16 F21 F22 F23 F24 F25 F26 01 c2 co c4 c11 c12 C13 C14 C15 C16 c21 c22 C23 C24 C25 C26 C31 C32 c33 c34 c35 C06 C41 C42 c43 c44 c45 C46 C51

Organometallics, Vol. 5, No. 2, 1986 347

Table 11. Positional Parameters and Their Estimated Standard Deviationsa Y 2 B , A2 atom X Y z 0.1162 (5) 0.4012 (8) 0.0610 (8) 2.166 (8) C52 0.11090 (3) 6.26436 (2) 0.4618 (9) 0.0927 (9) 0.0800 (6) 2.159 (8) c53 0.20046 (3) 0.22463 (2) 0.547 (1) 0.1087 (6) 0.1723 (9) 0.04172 (3) 2.168 (8) c54 0.26799 (2) 0.5768 (9) 0.1720 (5) 0.2204 (8) c55 5.37 (9) 0.2445 (3) 0.5404 (2) 0.5177 (8) 0.2102 (5) 0.1915 (8) C56 0.1938 (3) 6.3 (1) 0.9755 (2) 0.1159 (6) 0.4269 (6) 0.3095 (4) C61 2.52 (6) 0.0049 (2) 0.3181 (1) 0.5175 (8) 0.3224 (5) 0.0838 (7) 2.68 (6) C62 0.2201 (2) 0.2438 (1) 0.1114 (7) 0.5781 (8) 0.3862 (5) 2.53 (6) C63 0.3447 (2) 0.2275 (1) 0.5499 (8) 0.1695 (8) 0.4350 (5) 2.45 (6) C64 0.2213 (2) 0.1951 (1) 0.4611 (8) 0.4227 (5) 0.2012 (7) 2.61 (6) C65 0.0738 (2) 0.2729 (1) 0.3980 (7) 0.3601 (4) 0.1738 (7) 2.58 (6) C66 0.3126 (1) -0.0836 (2) 0.2120 (7) 0.1114 (4) 0.2463 (6) C71 0.2201 (6) 8.1 (2) 0.4647 (3) 0.2644 (8) 0.2966 (8) 0.0888 (5) 7.7 (2) C72 0.3584 (5) 0.5473 (3) 0.2854 (9) 0.0217 (5) 0.2230 (8) c73 9.9 (3) 0.2611 (6) 0.6141 (3) 0.1940 (9) 0.1634 (8) -0.0186 (5) c74 8.5 (2) 0.1317 (5) 0.5326 (4) 0.0022 (6) 0.109 (1) 9.8 (3) 0.1439 (9) c75 0.1995 (7) 0.5290 (4) 0.1192 (9) 0.0674 (5) 11.8 (3) 0.1830 (8) C76 0.2857 (6) 0.5486 (5) 0.3879 (6) 0.2355 (4) 0.3355 (7) 12.0 (3) C81 1.0376 (4) 0.2601 (8) 0.4094 (8) 0.3868 (7) 0.2879 (5) 12.0 (3) 0.1003 (7) C82 0.9667 (5) 0.4988 (8) 0.3196 (5) 0.4680 (8) 9.5 (3) 0.1265 (7) C83 0.9129 (4) 0.2951 (6) 0.5129 (9) 0.5452 (8) C84 11.9 (3) 0.2850 (6) 0.9807 (4) 0.2461 (6) 0.4434 (9) 0.5502 (9) C85 9.9 (8) 0.2394 (6) 0.9332 (1) 0.2143 (5) 0.3509 (8) 9.5 (3) 0.4694 (7) C86 1.0198 (4) 0.1506 (6) 0.3395 (4) 0.4204 (6) 0.1846 (7) c91 -0.0072 (5) 3.6 (2) 0.1374 (3) 0.2294 (8) 0.3872 (5) 0.3838 (7) C92 0.3010 (7) 3.1 (2) 0.1969 (4) 0.3160 (9) 3.1 (2) 0.4377 (5) 0.4491 (8) 0.1098 (7) c93 0.2015 (4) 0.3545 (9) 0.4386 (6) 0.5448 (9) 2.9 (2) -0.0456 (7) c94 0.3605 (4) 0.3105 (9) 0.3936 (5) 0.5815 (8) c95 2.7 (2)* 0.0588 (7) 0.3799 (4) 0.2235 (8) 0.3422 (5) 4.2 (2)* 0.5188 (7) C96 0.1150 (8) 0.4410 (5) 0.2744 (4) -0.0289 (7) 0.4034 (6) ClOl 5.3 (3)* 0.1659 (9) 0.4874 (5) 0.3324 (5) -0.0367 (8) 0.4649 (7) c102 4.8 (3)* 0.1593 (8) 0.4720 (5) 0.3339 (5) -0.1159 (9) 0.5150 (8) C103 5.4 (3)* 0.1055 (9) 0.4122 (5) 0.2780 (5) -0.1865 (9) 4.2 (2)* 0.0543 (8) 0.5024 (8) C104 0.3658 (5) 0.2204 (5) -0.1832 (8) 2.5 (2)* -0.1084 (6) 0.4399 (8) C105 0.2647 (4) 0.2184 (5) -0.1040 (8) 0.3897 (7) C106 3.7 (2)* -0.1797 (7) 0.2905 (5) 4.8 (3)* 0.3675 (4) -0.1181 (7) 0.2268 (6) Clll -0.2673 (8) 0.2496 (5) c112 0.4257 (5) -0.0443 (8) 5.4 (3)* 0.2867 (7) -0.2832 (9) 0.1849 (5) C113 0.4677 (5) -0.0673 (9) 5.5 (3)* -0.2143 (9) 0.3680 (8) 0.1590 (5) C114 0.4523 (5) -0.1609 (9) 0.3898 (8) 3.6 (2)* -0.1247 (7) 0.1999 (5) 0.3342 (9) C115 3.1 (2)* 0.3959 (6) -0.2311 (9) 0.3125 (7) 0.3086 (4) 0.2509 (8) C116 4.3 (2)* 0.3532 (5) -0.2135 (8) 0.3795 (8) 0.2957 (5) c121 0.2502 (4) -0.2036 (7) 0.4558 (9) 0.0520 (6) 5.3 (3)* 0.3466 (5) 0.0617 (7) c122 0.1899 (5) -0.2180 (8) 0.4610 (8) 4.8 (3)* 0.4075 (5) 0.3931 (8) 0.0018 (8) C123 0.1392 (6) -0.3094 (9) 4.7 (3)* 0.4208 (5) 0.3191 (7) -0.0623 (8) C124 0.1525 (6) -0.3807 (9) 3.4 (2)* 0.3712 (4) 0.1427 (7) -0.0720 (8) C125 2.9 (2)* 0.2099 (5) -0.3680 (9) 0.1931 (4) -0.0132 (7) C126 0.2612 (4) -0.2785 (7) 0.0920 (9) 5.1 (3)* 0.1298 (5) 0.705 (1) 0.415 (1) 0.1391 (8) 0.022 (1) 6.6 (3)* 0.0906 (6) O(S1) 0.373 (2) 0.081 (1) 0.636 (2) 6.8 (3)* 0.006 (1) 0.1199 (6) C(S2) 0.067 (1) 0.271 (2) 0.563 (2) 0.051 (1) 6.5 (3)* 0.1829 (6) C(S3) 0.1228 (8) 0.643 (2) 0.039 (1) 0.437 (2) 4.3 (2)* 0.2198 (5) C(S4) 0.4295 ( 7 ) 3.2 (2)* 0.1818 (4)

B , A2 4.5 (2)* 5.7 (3)* 6.3 (3)* 5.5 (3)* 4.6 (3)* 2.3 (2)* 3.8 (2)* 4.4 (2)' 4.6 (2)* 4.2 (2)* 3.2 (2)* 2.9 (2)* 4.6 (3)* 5.7 (3)* 5.5 (3)* 6.4 (3)* 5.2 (3)* 2.8 (2)* 4.2 (2)* 4.8 (3)* 5.5 (3)* 5.7 (3)* 4.2 (2)* 2.7 (2)* 3.8 (2)* 5.4 (3)* 5.9 (3)* 5.3 (3)* 4.1 (2)* 3.0 (2)* 4.3 (2)* 5.3 (3)* 5.2 (3)* 4.8 (3)* 3.9 (2)* 3.0 (2)* 4.0 (2)* 5.1 (3)* 5.6 (3)* 5.8 (3)* 4.6 (3)* 3.0 (2)* 4.2 (2)* 5.6 (3)* 5.5 (3)* 5.1 (3)* 3.5 (2)* 18.9 (6)* 21 (1)* 16.1 (8)* 17.2 (9)*

Atoms with an asterisk were refined isotropically. Anisotropically refined atoms are given in the form of the isotropic equivalent thermal parameter defined as (4/3)[a2B(l,l)+ b2B(2,2)+ c2B(3,3) + ab(cos 7)B(1,2) + ac(cos @)B(1,3)+ bc(cos a)B(2,3)]. methanol (10 mL). Upon addition of the NH4[PFB]solution a in a Parr pressure reactor (300-mL capacity) using methanol (50 flocculent orange precipitate formed. This product was filtered, mL) and distilled water (4 mL), which had initially been purged washed with methanol (1 mL), and dried in vacuo: yield 82%; with Nz, as solvent. The system was allowed to react for 71 h a t mp 275-285 "C dec. Anal. Calcd for [~GL3-CO)GL-dppm)31[PF612: 100 "C. At 15-h intervals, the pressure reactor was cooled and C, 44.39; H, 3.24. Found: C, 44.69; H, 3.52. Single crystals of a fresh CO atmosphere was introduced. After this period the the acetone solvate were grown as small red plates from acesystem was cooled to room temperature, the reactor was opened, tone-pentane by slow diffusion: IR 1765 cm-' [v(CO)]. 'H NMR and the solution was filtered. The solvent was evaporated from the filtrate under vacuum to give the crude product as an orange [(CD,),CO]: 6 6.26, 5.66 [m, %T(HnHb)= 14, 3J(PtHa) = 72, 3J(PtHb)= 14 Hz, CHaHbPz]. 31PNMR [CD,CO]: 6 -6.7 [s, solid, yield 97.5%. A sample was purified by recrystallization from an acetone'J(PtP) = 3710, 3J(PP)= 140 Hz, 31P]. Ig5PtN M R 6 -2893 [t, pentane solvent system and characterized by elemental analysis. 'J(PtP) = 3730, 'J(PtPt) = 540 Hz]. For the X-ray data collection a small crystal was selected and IR: 1750 cm-' [u(CO)]. 'H NMR ((CD3)2CO): 6 5.85, 5.56 [m, coated with thin layers of epoxy resin; preliminary studies had 2J(HaHb)= 14, ,J(PtHa) = 52, 3J(PtHb)= 16 Hz, CHaHbP2]. 31P shown that uncoated crystals decayed rapidly in the X-ray beam. NMR [(CD,)&O]: 6 -15.1 [s, 'J(PtP) = 3720, 'J(PP) = 170 Hz, Crystal d a t a (at 21 "C) for [Pt3(p-CO)(p-dppm)3][PF6]2* 31P]. 195PtN M R 6 -2685 [t, 'J(PtP) = 3740, 'J(PtPt) == 380 Hz]. Anal. Calcd for [Pt3(CO)(dppm)3][CF3COz]2-(CH3)zCO: C, 48.6; (CH3)&O: C79H72F1202P8Pt3; M,= 2114.5, triclinic, a = 14.090 H, 3.5. Found: C, 49.0; H, 3.9. (2) A, b = 22.711 (4) A, c = 13.637 (4) A; a = 103.43 (2)", p = 99.52 (2)O, y = 106.72 (1)"; U = 3937 (4) A3;2 = 2, D d d = 1.784; F(000) Preparation a n d Crystal S t r u c t u r e Analysis of [Pt3(p3o = 56.1 cm-'; C O ) ( ~ - ~ P P ~ ) ~ ] [ P FCrude & . ~ P S ( ~ ~ - C O ) G - ~ P P ~ ) ~ I [=C2048; F ~ CMo ~ ~Ka I ~radiation, X = 0.71069 A; ~ ( M KLY) space group P1 or Pi;Pi chosen and confirmed by the analysis. (0.334 mmol) was reacted with excess NH4[PF,] (8.190 mmol) in

348

Organometallics 1986, 5, 348-355

Accurate cell dimensions and crystal orientation matrix were determined on a CAD4 diffractometer by a least-squarea treatment of 25 reflections with 0 in the range 10-15'. The intensities of reflections with h, -13 to +13, k, -21 to +21, and 1,0 to +13, with 2' < 0 < 20' were measured by the w-26 method using graphite-monochromatized Mo K a radiation. The intensities of three reflections chosen as standards were monitored every 0.83 h and showed no evidence of crystal decay. The intensities of 8060 reflections were measured of which 7318 were unique after averaging. Of these 6234 and I > 3u(I) and were used in the structure solution and refinement. Data were corrected18 for Lorentz and polarization effects and later for absorption. The crystal used for the data collection measured 0.10 X 0.20 X 0.43 mm; the maximum and minimum values of the transmission coefficients are 0.601 and 0.311, respectively. Structure Solution and Refinement. The coordinates of the three Pt atoms were deduced from a three-dimensional Patterson function computed with data which had not been corrected for absorption; the remaining non-hydrogen atoms of the cation and anions were located from neccessive rounds of structure factor and difference electron density maps. Initial isotropic full-matrix refinement of the atoms was followed by five cycles in which the non-phenyl atoms were allowed anisotropic vibration. A difference map computed at this stage showed clearly that acetone of solution had been entrapped in the crystal lattice; maxima consistent with many of the hydrogen atoms of the structure were also present. The composition of the unit cell having now been established, the data were corrected for absorption. In the final rounds of full-matrixcalculations the solvate 0 and C atoms and the phenyl C atoms were allowed isotropic vibration, all other non-hydrogen atoms were allowed to vibrate anisotropically,and the 66 hydrogens of the cation were positioned (18) All calculations were made on a PDP-11/73 computer using the SDP-PLUS system, (B.A. Frenz and Associates, Inc., College Station, TX 77840, and Enraf-Nonius, Delft, Holland).

on geometrical grounds (C-H = 0.95 A) and included in the calculation (with an overall Bi, of 5.0 A') but not refined. The acetone of solvation is very loosely held in the lattice (average B , for acetone atoms 18 A2), and no allowance was made for the six acetone hydrogens. Refinement converged with R = CllFol - IFcll/CIFoI = 0.035 and R, = (xw(lFol- lFc1)2/~wlFo12)1/2 = 0.046 for the 6234 observed reflections; R = 0.044 for all reflections. The number of variables in the final rounds of refinement was 557, and the "goodness of fit" value was 1.50. The maximum shift/error ratios were 0.02 for the x coordinate of atom C93 and 0.01 for the Biso parameter of atom C103. A final difference map computed at the end of the refinement calculations had three maxima greater than 0.3 e A-3 (0.6-1.3 e A-3) near the Pt atoms but no chemically significant features. In the refinement calculations, scattering factors and anomalous dispersion corrections were taken from ref 19;the weighting scheme was of the form w = 1/[2(F0) + 0.05 (F,2)1.

Principal dimensionsfor the structure are summarized in Table I. Table I1 lists the final fractional coordinates of the non-hydrogen atoms with their estimated standard deviations. Tables of all bond lengths and angles, thermal parameters, calculated hydrogen coordinates, and mean plane data and a structure factor listing are available as supplementary material.

Acknowledgment. Financial support from N.S.E.R.C. (Canada) t o G.F. and R.J.P. is gratefully acknowledged. Supplementary Material Available: Tables of all bond lengths and angles, thermal parameters, calculated hydrogen coordinates, and mean plane data and a listing of structure amplitudes (87 pages). Orderinginformation is given on any current masthead page. ~~~~

(19) "International Tables for X-ray Crystallography";The Kynoch Press, Birmingham, England, 1974; Vol. IV.

Metallocyclic Palladium( I I ) Complexes Possessing Six- and Seven-Membered Rings:' Synthesis and Structural Characteristics George R. Newkome,' Garry E. Kiefer, Yves A. Frere,2aMasayoshi Onishi,2bVinod K. Gupta, and Frank R. Fronczek Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803- 1804 Received June 10, 1985

The syntheses of several new cyclometalated Pd(I1) complexes, which contain either phenanthroline or bipyridine moieties, are described. These complexes achieve partial coordination to the metal core via

an sp3carbon anionic bond(s) and form fused cyclic ring systems with overall cis geometry. The dipyridyl ethylenic and ketonic ligands undergo facile cyclometalation to generate the symmetric 5.7.5 and 5.6.5 complexes, respectively; in contrast, the potentially tetracoordinate 6.5.6 ligand systems available with phenanthroline and bipyridine yielded only a single C-Pd bond. The single-crystal X-ray structural analyses of selected complexes have afforded insight into the molecular features responsible for precluding generation of dual C-Pd bonds in the 6.5.6 system.

Introduction Up t o this point, our interest in metallocyclic palladium(I1) complexes has been limited primarily to 2,2'-bipyridine- and 1,lo-phenanthroline-based ligands capable of forming a cis 5.5.5-cumulated ring ~ y s t e m . ~These C z 5 5 5 cumulated r i n g system

(1) Chemistry of Heterocyclic Compounds series. Part 121. (2) (a) On leave from Centre de Recherche sur lea Macromolecules, Strasbourg, France, 1982-1983. (b) On leave from Nagasaki University, Nagasaki, Japan, 1982-1983. (3) Newkome, G. R.; Puckett, W. E.; Kiefer, G. E.; Gupta, V. K.; Fronczek, F. R.; Pantaleo, D. C.; McClure, G. L.; Simpson, J. B. Deutsch, W. A. Inorg. Chem. 1985, 24, 811.

0276-7333/86/2305-0348$01.50/0

prototypes were designed specifically for the encapsulation of square-planar transition-metal ions and, with the exception of the phenanthroline derivatives, have demonstrated a propensity for generating very stable tetradentate complexes in which partial coordination is achieved via sp3 0 1986 American Chemical Society