Inorganic Chemistry, Vol. 18, No. 4 , 1979 M. H. Chisholm and S. Godleski, Prog. Inorg. Chem., 20, 299 (1976). M. Hirota, Y. Koike, H. Tshizuka, A. Yamasaki, and S. Fujiwara, Chem. Lert., 853 (1973). A. D. James and R. S. Murray, Inorg. Nucl. Chem. Left.,12,739 (1976). D. Dykes, T. K,Huckerby, and C. Oldham. Inorg. Nucl. Chem. Lett., 13, 63 (1977). J. M. Malin, C. F. Schmidt, and H. E. Toma, Inorg. Chem., 14, 2924 (1975). K. F. Miller and R. A. D. Wentworth, Inorg. Chem., 15, 1467 (1976). J. E. Figard, J. V. Paukstelis. E. F. Bryne, and J. D. Petersen, J . Am. Chem. Soc., 99, 8417 (1977). C. Brown, B. T. Heaton, and J. Sabounchei, J . Organomet. Chem., 142, 413 (1977). A. G. Sharp, “Chemistry of Cyano Complexes of the Transition Metals”, Academic Press, London, 1976. F. Krause and G. Schrader, J . Prakt. Chem., 119, 279 (1928). F. Krauss and H. Umbach. Z . Anorg. Allg. Chem., 179, 357 (1929). F. P. Dwyer and J. W. Hogarth, Inorg. Synth., 5, 206 (1957). J. H.Bigelow, Inorg. S y n f h . ,2, 225 (1946). H. Siebert and A. Siebert, Angew. Chem., 81, 575 (1969); 2 . Anorg. Allg. Chem., 378, 160 (1970). D. L. Swihart and W. R. Mason, Inorg. Chem., 9, 1749 (1970). W. C. Fernelius and J . J. Burbage, Inorg. Synrh., 2, 227 (1946). J. H. Bigelow, Inorg. Synth., 2, 245 (1946). “Gmelins Handbuch der Anorganischen Chemie”, Vol. 68c, Part 2, 8th ed., Verlag Chemie, Weinheim/Bergstr, Germany, 1940, p 201. J. M. Smith, L. H. Jones, J. K. Kessin, and R. A. Penneman, Inorg. Chem., 4, 369 (1965). W. R. Mason, J . A m . Chem. SOC.,95, 3573 (1973). 0. Glemser and H. Sauer, “Handbook of Preparative Inorganic Chemistry”, Val. 11, 2nd ed., G . Brauer, Ed., Academic Press, New York, 1965, p 1065. E. Staritzky and F. H. Ellinger, Anal. Chem., 28, 422 (1956).
Sanner et al. (24) (25) (26) (27) (28)
Reference 22, p 1064. J. J. Pesek and W. R. Mason, J . Magn. Reson., 25, 519 (1977). G . M. Bodner and L. J . Todd, Inorg. Chem., 13, 1337 (1974). P. S. Braterman, D. W. Milne. E. W . Randall, and E. Rosenberg, J . Chem. Soc.. Dalton Trans.. 1027 119731. J . B. Stothers, “Carbon-I 3 NMR Spectroscopy”, Academic Press, New York: 1972. ~ n j 304. r J.Evans and J. R . Norton, Inorg. Chem., 13, 3042 (1974). M. Karplus and J. A. Pople, J . Chem. Phys., 38, 2803 (1963). A large contribution to the screening tensor is also made by the “diamagnetic” term, Vd. changes in which are assumed to be small when comparisions are made between similar complexes, e.g., complexes of metals adjacent to one another in the same row in the periodic table. However, the magnitude of ud is dependent upon the nuclear charge of atoms bound to carbon and therefore may change considerably for analogons complexes of metals in different rows of the periodic table.27 There appears to be some disagreement as to the im ortance of the role of “d in influencing observed I3C chemical s h i f t ~ . ~ f ~ ~ D. A. Brown, J. P. Chester. N. J. Fitzpatrick, and I. J. King, Inorg. Chem., 16, 2497 (1977). D. G. Cooper and J. Powell, Inorg. Chem., 16, 142 (1977). T. Yonemoto, J . Magn. Reson., 12, 93 (1973). L. H. Jones, Inorg. Chem., 2, 777 (1963). M. N . Memering, L. H. Jones, and J . C. Bailar, Inorg. Chem., 12. 2793 ( I 973). h’onpentration is implied by low participation of the filled metal nd orbitals in bonding. The electronic structures of Au(CN),- and Hg(CN), for example have been discussed in terms of only a small perturbation of the filled 5d shell by the CN- ligands. See W. R. Mason, J . A m . Chem. Soc., 98, 5182 (1976). T. C. Farrar and E. D. Becker, “Pulse and Fourier Transform KMR”, Academic Press, New York, 197 I , p 60. Reference 38, p 62. 1~
(29) (30) (31)
(32) (33) (34) (35) (36) (37)
(38)
(39)
~~
Contribution from the Departments of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 021 39. and University of Alabama, University, Alabama 35486
Comparison of the Photocatalytic Behavior of Phosphinated Polymer-Anchored Iron Carbonyl Species and Homogeneous Phosphine Substituted Iron Carbonyl Species: Alkene Isomerization and Reaction with Trialkylsilanes R O B E R T D . S A N N E R , R I C H A R D G . A U S T I N , M A R K S. \’RIGHTON,* W I L L I A M D . H O N N I C K , and C H A R L E S U. P I T T M A N , JR.* Receiued November 16, 1978
A styrene-1% divinylbenzene resin whose phenyl rings have been derivatized with PPh2 groups serves as an “anchor” for Fe(CO), ( n = 3 , 4 ) groups; the anchor is the Fe-P bond. The photocatalytic activity of suspensions of the polymer-anchored Fe(CO), has been compared to that of homogeneous solutions of Fe(CO),(PPh3)5_n( n = 3-5). 1-Pentene isomerization and reaction with HSiEt, can be affected with each system. Observed quantum yields for I-pentene isomerization exceed unity for each catalyst precursor, and the initial trans- to cis-2-pentene ratio depends on the catalyst precursor, implicating the retention of the triarylphosphine groups in the actual catalytically active species. Irradiation of Fe(CO),(PPh3)5_, ( n = 4) results in loss of C O , not PPh3, suggesting a photoinert anchor to the Fe(CO), groups in the polymer systems. These experiments establish the viability of photogenerating catalysts anchored to polymer supports without destruction of the anchor bond in the photogeneration procedure.
Recent studies have shown that photogenerated coordinatively unsaturated intermediates are capable of serving as catalysts for a variety of reactions involving o1efins.’-l0 W e have reasoned that it may be possible to generate metalcentered catalysts which are extensively coordinatively unsaturated by irradiation of polymer-anchored, but fully coordinatively saturated, organometallic complexes, The simple notion is that the polymer-anchored species may be “matrix isolated” in the sense that the photogenerated intermediates are incapable of reacting with one another to generate catalytically inactive aggregates. It is well established, for example, that irradiation of mononuclear binary metal carbonyls in rigid matrices a t low temperature results in extensive loss of CO. and in several instances all CO’s can be dissociated *To whom correspondence should be addressed: M.S.W., Massachusetts Institute of Technology; C.U.P., University of Alabama.
0020-1669/79/1318-0928$01.00/0
from the metal to generate elemental Consequently, the generation of multiply coordinatively unsaturated species seems a reasonable possibility in the anchored systems. Importantly, such an approach may provide a way to study the reactions of such sites under conditions where sufficient thermal activation energy exists to study catalytic chemistry but at milder conditions than would be required for thermal generation of multiple coordinative unsaturation. By now the study of polymer-anchored thermal catalysts is ~ e l l - k n o w n , * but ~ - ~polymer-anchored ~ systems exposed to light have received little detailed study. The aim of this report is to describe our results pertaining to the photocatalytic activity of Fe(CO), ( n = 3, 4) species anchored to a phosphinated styrene-divinylbenzene resin. An important component of the results concerns the parallel study of homogeneous “models” of the polymer-anchored systems. Owing to a number of previous photocatalytic s t u d i e ~ , ~there . ’ ~ is
0 1979 A m e r i c a n Chemical Society
Inorganic Chemistry, Vol, 18, No. 4, 1979 929
Photocatalytic Behavior of Iron Carbonyl Species
Table 11. Polymer-Anchored Photocatalyzed 1-Pentene Isomerization in Isooctane and Benzeneu
Table I. Infrared Bands in the CO Stretching Region for the Complexes Studied bands, cm-' (e, L mol-' cm-')=
complexes
solvent
WCO), Fe(CO),(PPh,) tvans-Fe(CO), (PPh, ) e [(PAPh)iPPH,'] s-no-'' Fe(CO), (n = 3,4)b
2025 (5470), 2000 (11 830) 2054 (3500), 1977.5 (2310), 1942 (4870) 1892.5 (5 140) 2045 (-), 1968 (-), 1932 (-), 1876 (-)
% 1pentene
% trans-2pentene
% cis-2pentene
0
100 70.4 100 99.7
0 21.4 0 0.20
0
benzene
12
0
isooctane
12
8.2
0
