Early-transition-metal phosphides and their application towards the synthesis of heterobimetallic complexes.

摘要

Novel early-transition-metal phosphido species have been prepared and used as u22metalloligandsu22 in the synthesis of heterobimetallic complexes. Reaction of TiCl$sb4$ with three equivalents of LiNR$sb2$ (R = Me, Et) produces the amido complexes, (NR$sb2)sb3$TiCl (R = Me, 1; Et, 2). Compound 1 crystallizes in the trigonal space group, R3c with a = 11.525(5) A, c = 14.939(3) A, Z = 6 and V = 1718(1) A$sp3.$ The ethyl analogue, 2, crystallizes in the monoclinic space group, P2$sb1/$c with a = 8.385(2) A, b = 15.958(2) A, c = 14.230(4) A, $eta$ = 107.79(1)$spcirc,$ Z = 4 and V = 1813(1) A$sp3.$ The structural data imply Ti-N multiple bonding consistent with the expected Lewis acidity of these compounds. The tris-amido species were then converted to the metalloligands, (NR$sb2)sb3$TiPCy$sb2$ (R = Me, 3; Et, 4), which were characterized by $sp1$H-, $m sp{13}C{sp1H}$- and $m sp{31}P{sp1H}$ NMR spectroscopy. The early/late heterobimetallics, ((NR$sb2)sb3$Ti($mu$-PCy$sb2)$) $sb2$Rh(PPh$sb3)($CO)H (R = Me, 5; Et, 6), were subsequently synthesized demonstrating the utility of 3 and 4 as metalloligands. Heterobimetallics demonstrating activation of a CO ligand have been prepared via redox reactions of (CpMo(CO)$sb3$) $sb2$ with Ti(III) and Zr(III) phosphides of the form, (Cp$sb2$M($mu$-PEt$sb2)$) $sb2.$ During the course of these reactions, vacant coordination sites are created on the early metal. The reaction with the Zr(III) phosphide results in the Zr(IV)/Mo complex, Cp$sb2$Zr($mu$-PEt$sb2)(mu$-$etasp1,etasp2$-OC)Mo(CO)Cp (10). This compound was completely characterized by NMR and IR spectroscopy. An X-ray study of 10 determined that it crystallizes in the monoclinic space group P2$sb1/$c with a = 14.644(2) A, b = 9.795(2) A, c = 14.667(3) A, $eta$ = 104.27(1)$spcirc,$ Z = 4 and V = 2039(1) A$sp3.$ In this compound, activation of one of the Mo-bound carbonyl ligands is achieved through donation of x-electron density of the C$equiv$O bond to the Zr centre. The reaction of the Ti(III) phosphido dimer proceeds via an alternative pathway. In this case, the isocarbonyl complex, Cp$sb2$(THF)Ti($mu$-OC)Mo(CO)$sb2$Cp (11), is produced. This Ti(III)/Mo bimetallic crystallizes in the space group P1 with a = 16.230(4) A, b = 7.907(2) A, c = 10.882(3) A, $lpha$ = 115.39(1)$spcirc,$ $eta$ = 82.99(2)$spcirc,$ $gamma$ = 124.66(2)$spcirc,$ Z = 2 and V = 1029(1) A$sp3$ and was further characterized by ESR and IR spectroscopy. In the course of preparing bimetallics from Ti(III) phosphides, the physical and structural properties of these starting materials were examined. (Abstract shortened by UMI.)Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses u26 Major Papers - Basement, West Bldg. / Call Number: Thesis1991 .D535. Source: Dissertation Abstracts International, Volume: 53-01, Section: B, page: 0268. Adviser: Douglas W. Stephan. Thesis (Ph.D.)--University of Windsor (Canada), 1991.