REACTIONS OF SOME TRIOSMIUM CLUSTERS OF THE TYPE OS3(MU-H)2(CO)9AR(AR = C6H4, C9H6, C4H3N, OR C4H2NME) WITH PHOSPHINES AND PHOSPHITES - X-RAY CRYSTAL-STRUCTURE OF OS3(MU-H)2(CO)7[P(OME)3]2(C4H3N)

Triosmium clusters with the formulation Os3(mu-H)2(CO)9Ar[Ar = C6H4 (1), C9H6 (2), C4H3N (3), or C4H2NMe (4)] can be chemically activated by reaction with Me3NO/MeCN to produce the reactive species Os3(mu-H)2(CO)9-n(MeCN)nAr[n = 1, Ar = C6H4 (5), C9H6 (6), C4H3N (7), or C4H2NMe (8); n = 2, Ar = C6H4 (9), C9H6 (10), C4H3N (11), or C4H2NMe (12)], which then react with phosphine or phosphite molecules to give substituted products Os2(mu-H)2(CO)9-n(PR3)nAr(n = 1, or 2, R = Ph, Et, or OMe). These clusters have been characterised by spectroscopic techniques, and Os3(mu-H)2(CO)7[P(OMe)3]2(C4H3N) (24) has been structurally characterised by an X-ray analysis. In this complex one of the phosphite ligand occupies an axial site on the osmium triangle while the second occupies a more conventional equatorial site. The C4H3N ligand caps the triangle and is coordinated through the nitrogen and one carbon atom.