摘要:
814 CHEMICAL COMMUNICATIONS The Structure of Methylmethoxycarbenetriphenylphosphinetetracarbonylchromium By 0. S. MILLS and A. D. REDHOUSE (Department of Chemistry, University of Manchester, Mamhester 13) THE molecular structure of phenylmethoxycarbene- pentacarbonylchromium (I) was recently rep0rted.l Substitution of one carbonyl group by triphenyl- phosphine is accompanied by an increase in stability towards atmospheric oxidation.a We have now analysed the crystal structure of methylmethoxy- carbenetriphenylphosphinetetracarbonylchromium (11) to see whether the increase in stability is associated with any substantial change in structure, to obtain a second value for the chromium-carbene distance and to determine whether the triphenyl- phosphine group is cis or trans to the carbene group.We thank Professor E. 0. Fischer for supplying us with crystals of the compound.3 Me(MeO)C( Ph,P)Cr (CO), crystallises in space group P2Jn with a = 9.29, b = 22.61, c = 11*60A, 18 = 92-57" and 2 = 4. The structure was deter- mined by Fourier methods from 833 reflexions collected on precession photographs taken with molybdenum K , radiation (I? = 8.2%). The structure shown in the Figures confirms the basic geometry found for (I). The chromium-carbene distance, 2.04 A, is the same as in (I) and is significantly longer than the remaining Cr-C distances (average 1.84 A). Some differences, however, are found. One minor change is that the normal to the plane of the substituted carbene in (11) lies approximately a t 65' to one of the principal axes of the chromium octahedron as compared with 45' in (I).We conclude that the replacement of the phenyl group in (I) by methyl is not accompanied by largeNUMBER 22, 1966 815 differences in arrangement. One interesting atom by the substituents is increased from 104' difference, however, does occur. In (11) the in (I) to 115" in (11). methoxy-group is bent away from the chromium The triphenylphosphine group is cis and the atom whereas in (I) the reverse occurs. Addition- Cr-P distance 2.42 A. The P-C distances, average ally the angle subtended at the carbene carbon 1-82 A, compare well with those found in triphenyl- phosphine itself (average 1.828 A) .4 0 FIGURE 2. The strzicture in Figure 1 9.otated th.rough 90'. FIGURE 1. (Received, September 19th, 1966; Cow. 703.) 1 0 . S. Mills and A. D. Redhouse, Angew. Chem., 1965, 77, 1142; Angew. Chem. Internat. Edw., 1965, 4, 1082. a E. 0. Fischer, Chemical Society Lecture, Nottingham, September 1965. E. 0. Fischer and R. Aumann, unpublished results. J. J. Daly, J . Chem. Soc., 1964, 3799.
ISSN:0009-241X
DOI:10.1039/C19660000814
出版商:RSC
年代:1966
数据来源: RSC