REACTIVITY OF CIS-PT(C6F5)2(OC4H8)2 TOWARD (C6H5)2CN2.SYNTHESIS AND MOLECULAR-STRUCTURE OF PT(C6F5)[(2-C6H4)C(C6H5)=N-N=(ETA-2-C6H5)C(C6H5)], AN ORTHO-METALATED COMPOUND CONTAINING AN UNUSUAL INTRAMOLECULAR ETA-2-ARENE-PT INTERACTION

Treatment of cis-Pt(C6F5)2(OC4H8)2 (1) with (C6H5)2CN2 (2) affords cis-Pt(C6F5)2[(C6H5)2C = N-N = C(C6H5)2] (4), which can also be obtained by reacting 1 with (C6H5)2C = N-N = C(C6H5)2 (3). A possible structure of complex 4 is discussed both in terms of its spectroscopical features and its chemical behavior. 4 undergoes an ortho-metalation process by thermolysis either in solution or in the solid state, yielding activated Pt(C6F5)[(2-C6H4)C(C6H5) = N-N = (eta(2)-C6H5)C(C6H5)] (7), which has been structurally characterized by an X-ray diffraction study. 7 crystallizes in monoclinic space group P2(1)/n with a = 11.8359 (6) angstrom, b = 14.2561 (7) angstrom, c = 15.4549 (9) angstrom, beta = 103.200(5)-degrees; V = 2539 (1) angstrom 3, and Z = 4. One of the phenyl rings of the ortho-metalated benzophenone azine is eta(2)-coordinated to platinum, the whole ligand acting as tridentate. The eta(2)-aryl-Pt coordination, present in 7 and postulated in 4, is released by reaction of each compound with CO, thereby giving rise to activated Pt(C6F5)[(2-C6H4)C(C6H5) = N-N = C(C6H5)2](CO) (8) and cis-Pt(C6F5)2[(C6H5)2C = N-N = C(C6H5)2](CO) (5), respectively.