## LSU Historical Dissertations and Theses

1989

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

George R. Newkome

#### Abstract

The syntheses of several new metalated and cyclometalated organoplatinum(II) complexes of $C$-malonato ligands have been accomplished. These complexes were characterized by $\sp1$H and $\sp{13}$C NMR and IR. The trans cyclometalated complexes utilized pyridinyl ligands possessing pendant groups at the 2-position with terminal malonate groups capable of forming either a five- or six-membered $C,N$-chelate. X-ray crystal structure determinations of these cyclometalated complexes were also done. The acyclic cis complexes are $N,N\sp\prime$-chelates of dipyridine or phenanthroline in which platinum is bonded to the central carbons of two different dimethyl malonate ligands. These $N,N\sp\prime$-chelates were easily oxidized by either Br$\sb2$ or Cl$\sb2$ to give the corresponding Pt(IV) complexes; interestingly, this oxidation could also be accomplished by Cu(II) halides. The stability and reactivity of these complexes were also studied. A $\sp{13}$C NMR spectral analysis of the $N,N\sp\prime$-chelates showed that when two paths for Pt-C coupling are available, the observed coupling constant is the sum of the two individual coupling constants. Very few examples of cyclometalated 2-vinylpyridines have been reported, but, by the employment of $\alpha$-substituted 2-vinylpyridine derivatives, the synthesis of novel cyclometalated dimers was achieved. These dimers were readily cleaved by pyridine or triphenylphosphine and the structure of one of these monomers was proven by an X-ray crystal structure determination which showed the existence of the metal-alkenyl bond. Methyl functionalization of 2-methyl- and 2,7-dimethyl-1,8-naphthyridine was accomplished by a three-step synthesis. The methyl group was first oxidized to the trichloromethyl group by $N$-chlorosuccinimide. Subsequent hydrolysis with H$\sb3$PO$\sb4$/MeOH gave the methyl ester which was reduced to an alcohol with NaBH(OMe)$\sb3$ which does not readily reduce less reactive esters. Because of the enhanced reactivity of the naphthyridine system, reagents (e.g. H$\sb2$SO$\sb4$, and NaBH$\sb4$, (and NCS/CCl$\sb4$ for 2-methyl-1,8-naphthyridine)) that were used on other heterocycles could not be used on naphthyridine.

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