摘要:
Chemical Com mu n ications NUMBER 16/1968 21 AUGUST New Routes to Fluorocarbon Nickel Complexes By JANE BROWNING, D. J. COOK, C. S. CUNDY, M. GREEN, and F. G. A. STONE* (Department of Inovganic Chemistry, The University, Bristol 8) TREATMENT of tetrakistriphenylphosphine-pallad- iuni or -platinum with certain fluorocarbon compounds has led to the synthesis of a variety of complexes, for example (Ph,P),Pd [(CF,),CO] or (Ph,P),Pt[C,F,].2 We have now found that bis(cyc10-octadiene)nickeP and allylnickel com- pounds such as bis(methallyl)nicke14 are highly reactive towards fluorocarbons, forming fluoro- organonickel complexes of a new type. Bis- (2-methally1)nickel reacts rapidly with tetra- fluoroethylene forming a deep red crystalline complex, C,,H,,F,Ni (I), m.p. 110-111". The lH and l9F n.m.r.spectra are in accord with the structure proposed, with proton signals a t T 4-95 (2H, d, JHH < 0-5 c./sec.), 5.17 (2H, d, JHH < 0-5c./sec.), 7.22 (4H, t, JHF 18.0 c./sec.), and 8.01 (6H, s); and fluorine resonances (relative to CC1,F) a t 100.7 (4F, s ) and 107-9 (4F, t, JHF 18-0 c./sec.). Formation of a tetrafluoroethylene complex is of interest in itself, but the concomitant insertion of a second tetrafluoroethylene molecule between two rr-methallyl groups to form the 4,4,5,5-tetrafluoro- 2,7-dimethylocta- 1,7-diene system is without pre- cedent. Treatment of (I) with iodine affords CH, : CMeCH,(CF,),CMeCH : CH,. Bis(cyclo-octa-l,5-diene)nickel reacts with hexa- fluoroacetone and 2,2,4,4- tetrakis (trifluoromethyl) - 1,3-dithietan below 0" to afford, respectively, the orange crystalline complexes (II), decomp.> 82" and (111), m.p. 165.5". Treatment of (11) or (111) with the ligands Ph,PMe, Ph,P, (PhO) sP, EtC(CH,O) ,P, [Ph,PCH,],, or dipyridyl results in displacement of cyclo-octa- 1,5-diene and the formation in high yield of the stable crystalline complexes (IV) and (V) respectively. The complex (IV; L = Ph,PMe) can also be pre- pared by treating tetrakis(methyldipheny1phos- phine)nickel with hexafluoroacetone. Analytical and molecular weight data, infrared and n.m.r. spectra, and degradation studies are all in accord with the structures proposed for com- plexes (11)-(V). In its infrared spectrum, hexa- fluoroacetone shows a strong carbonyl stretching band6 a t 1807 cm.-l. No such band is present in the spectra of complexes (11) or (IV), nor are there bands assignable to either the arrangement (CF,),C=O-+Ni or to a rr-complex of hexafluoro- acetone and nickel.Moreover, the absence of terminal metal carbonyl bands or acyl carbonyl bands excludes structures [e.g. (CF,),NiL,(CO) or CF,CONiL,(CF,) ] in which hexafluoroacetone has become fragmented on co-ordination. The possi- bility is further disproved by chemical properties and l9F n.m.r. studies. Treatment of (11) with carbon monoxide afforded tetracarbonylnickel, cyclo-octa- 1, 5-diene, and hexafluoroacetone. The 19F spectra of (11) and (111) show sharp singlets at 68.1 and 57.9 p.p.m. respectively, relative to CC1,F. The chemical shift of a CF, group directly attached to nickel is about -6.0 p.p.m.6 in accord with the generally observed low-field shifts of fluorine nuclei on carbon atoms a-bonded to transition metals.' Moreover, the n.m.r.data for (IV) and (V) are also in accord with a rigid three-membered ring system in that two phosphorus-fluorine coupling constants are observed. The 19F n.m.r. spectrum of [IV; L = (PhO),P], m.p. 130-131°,5 shows a band a t 66.5 p.p.m. (double-doublet, Jcid-PF 3.4, JL,anr.PF 929930 CHEMICAL COMMUNICATIONS, 1968 12.2 c./sec.); and similarly the spectrum of [v; The stability of the triangular NiCO L = (PhO),P], m.p. 133", has a band at 56.5 and NiCS structures in hexafluoroacetone and p.p.m. (double-doublet, J+PF 1.0, Jl,anr-PF hexafluorothioacetone complexes is interesting, and is demonstrated by the formation of (IV) and (V) from (11) and (111), respectively.The bonding for attachment of the (CF,),CO or the (CF,),S groups to nickel could be rationalized in terms of a ill' f F , !Ill' We thank the S.R.C. for a research studentship (C.S.C.) and the U.S. Air Force Office of Scientific (Received, May 9th, 1968; Corn. 580.) 12.0 c./sec.). . /y {'F, I ,y~: /::Ni, '<.F, I j three-centre molecular orbital scheme.* $:+:F: 6-1 1 ;:Nl+cF, -.' $ I s f C F j I., I ... i/i' .. c F, / i \ / Research for support. (v:l 1.' ' O (I\') Beverley Clarke, M. Green, R. B. L. Osborn, and F. G. A. Stone, J . Chem. SOC. ( A ) , 1968, 167. 2 M. Green, R. B. L. Osborn, 4 . J. Rest, and F. G. A. Stone, Chew. Comm., 1966, 502; J . Chem. SOC. ( A ) , in the press. 3 B. BogdanoviC, M. Kroner, and G. Wilke, Annalen, 1966,699, 1. * G. Wilke, B. BogdanoviC, P. Hardt, P. Heimbach, W. Keim, M. Kroner, W. Oberkirch, K. Tanaka, E. Steinriicke, 5 E. L. Pace, A. C . Plaush, and H. V. Samuelson, Spectrochim Acta, 1966, 22, 993. 7 E. Pitcher, A. D. Buckingham, and F. G. A. Stone, J . Chem. Phys., 1962,36, 124. D. Walter, and H. Zimmermann, Angew. Chem. Internat. Edn., 1966, 5, 151. D. W. McBride, E. Dudek, and F. G. A. Stone, J . Chem. SOC., 1964, 1752. J . -4. McGinnety and J. A. Ibers, Chem. Comm., 1968, 235.
ISSN:0009-241X
DOI:10.1039/C19680000929
出版商:RSC
年代:1968
数据来源: RSC