The first q p4 complex to be characterized by x ray

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Unformatted text preview: e bonded q 2 to the other two (Fe(C0)4} groups. The first q -P4 complex to be characterized by X-ray structural analysis was [(r~~-np3)Ni(q'-P4)1,(~~) formed by direct reaction of white P4 with the Nio complex [Ni(q4-np3)] in thf at 0°C where np3 is N(CH2CHzPPh2)3. Coordination results in a slight elongation of the tetrahedron with Pbasal -Papica1 220 pm and Pbasal-Pbasal 209 pm (cf. 221pm in a-Pq. The q2-P4 mode of coordination is featured in many complexes with Rh, Ir, etc., for example [RhCl(q2P4)(PPh3)2],(55) formed by direct reaction of P4 with [RhCl(PPh3)3] in CH2C12 at -78°C. The coordinated edge is almost perpendicular to the {RhClLZ} plane and is lengthened by s 2K. H. WHITMIRE, T. A. ALBRIGHT, S . K. KANG, M. R. CHURCHILL J. C. FETTINGER,norg. Chem. 25, and I 2799-805 (1986). 53 G . SCHMID H. P. KEMPNY,. anorg. allg. Chem. 432, and Z 160-6 (1977). 54 P. DAPPORTO, . MIDOLLINI S and L. SACCONI, ngew. A Chem. Int. Edn. Engl. 18, 469 (1979). s s W. E. LINDSELL,. J . MCCULLOIJGH A. J. WELCH, . K and J Am. Chem. SOC. 105, 4487-9 (1983). about 25 pm to 246.2 pm, whereas the other P-P distances are essentially unchanged from those in uncoordinated P4.(56) Square planar cyclo-P4 features as a ligand in [Nb(q5-C,H3Bu',-1,3)(CO)2(q4-P4)](57) and the corresponding Ta analogue.(58)The compounds are formed by uv photolysis of P4 with [M(cp*)(CO)4] and the square-pyramidal nido structure of the MP4 cluster (Fig. 12.9~) conis sistent with its 14e (2n 4) cluster-electron count (p. 161). The P-P distances in the coplanar P4 ligand are in the range 214-218pm for the Nb complex, with Nb-P4(centre) being 142pm and the basal PPP angles being 92.6" and 88.4". In the Ta complex, the P-P distances are 215-217 pm. A co-product of the photolysis reaction is the related bis-(PZ) complex [{T~(CC,H~B~',)(CO)(~,$-P~)}~], in Fig. 12.9d, which the P-P distance is 212pm within each P2 ligand and 351pm between the coplanar P2 ligands. Several similar binuclear bis-(P*) complexes are known, including FWRh, and mixed metal species involving NbRa and T~/CO.(~') A still more open configuration occurs in the zig-zag P4 chain shown in Fig. 12.10(a).(59) This was found in the dianion of the deep + 5 6A. P. GINSBERG,W. E. LINDSELL,K. .. CCULLOUGH, I M and C. R. SPRINKLE A. J. WELCH,J . Am. Chem. SOC. 108, 403-16 (1986). 5 70. SCHERER,J. VONDUNG J. and G. WOLMERSHAUSER, Angew. Chem. Znt. Edn. Engl. 28, 1355-7 (1989). " 0 . J . SCHERER, . WINTERand G . WOLMERSHAUSER, R 2. anorg. allg. Chem. 619, 827-35 (1993). s 9G. FRITZ, E. LAYHER, H. WUTSCHEID, B. MAYER, E. MATERN, HONLE H. G. VON SCHNERING,anorg. W. and Z. allg. Chem. 611, 56-60 (1992). Next Page...
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