SYNTHESIS AND SPECTROSCOPIC CHARACTERIZATION OF NOVEL HETEROTERMETALLIC ISOPROPOXIDES - X-RAY CRYSTAL-STRUCTURES OF ICD(M(2)(OPRI)(9)) AND [(CD(OPRI)(3))BA(M(2)(OPRI)(9))](2) (M=TI, HF)

Metathesis reactions between CdI2 and KM(2)(OPri)(9) (M = Ti, Hf) in t oluene produce monomeric iodo-heterobimetallic isopropoxides ICdM(2)(O Pri)(9) (1, M = Ti; 2, M = Hf) which have been characterized by soluti on (H-1, C-13 and Cd-113) and solid state (C-13 and Cd-113) CP MAS NMR spectroscopy, microanalysis, cryoscopic molecular weight determinatio n, and single crystal X-ray diffraction study. Both 1 and 2 in the sol id state represent the first structurally characterized examples of ha lide heterobimetallic alkoxides based on {Ti-2(OPri)(9)}(-) and {Hf-2( OPri)(9)}(-) bioctahedral subunits, respectively. The overall molecula r geometry of 1 and 2 can be viewed formally as an interaction of the CdI+ fragment with {M(2)(OPri)(9)}(-) substructures via two terminal a nd two bridging (mu(2)-) isopropoxy groups. Reaction of 1 and 2 with e quimolar KBa(OPri)(3) in toluene afforded novel heterotermetallic isop ropoxides [{Cd(OPri)(3)}Ba{M(2)(OPri)(9)}](2) (3, M = Ti; 4, M = Hf). Formation of heterotermetallic frameworks involves an interesting rear rangement of the central metal atoms between the two precursor molecul es, which is probably commanded by the tendency of barium to achieve h igher coordination numbers. The dimeric forms of 3 and 4 as shown by c ryoscopy and Cd-113 solution and solid state CP MAS NMR studies are co nfirmed by crystallography. The X-ray crystal structures of 3 and 4 re veal, as a common feature, a central u(2)-OPri)(2)-Cd(mu(2)-OPri)(2)Cd (mu(2)-OPri)(2)Ba unit formed by a spirocyclic linking of two LBa(OPri )(2) (3, L = Ti-2(OPri)(9); 4, L = Hf-2(OPri)(9)) units to a four memb ered, Cd-2(OPri)(2), ring. Crystal data: for 1, monoclinic, space grou p P2(1)/m, a = 11.71(2) Angstrom, b = 15.78(3) Angstrom, c = 12.16(2) Angstrom, beta = 116.69(14)degrees, Z = 2; for 2, triclinic, space gro up P (1) over bar, a = 9.825(2) Angstrom, b = 11.428 Angstrom, c = 20. 619 Angstrom, alpha = 95.619(12)degrees, beta = 99.915(11)degrees, gam ma = 111.347(11)degrees, Z = 2; for 3, monoclinic, space group P2(1)/c , a = 22.68(2) Angstrom, b = 12.603(11) Angstrom, c = 19.00(2) Angstro m, beta = 96.83(8)degrees, Z = 2; for 4, monoclinic, space group P2(1) /c, a = 23.197(5) Angstrom, b = 12.886(3) Angstrom, c = 19.378(4) Angs trom, beta = 97.18(3)degrees, Z = 2.