ORGANOMETALLIC RHODIUM(III) AND RHODIUM(I) COMPLEXES WITH 1,3-DIMETHYLLUMAZINE(DML) - THE CRYSTAL-STRUCTURE OF [(ETA(2)-(O-4,N-5)DML)(ETA(5)-C(5)ME(5))CLRH](PF6)
O. Heilmann et al., ORGANOMETALLIC RHODIUM(III) AND RHODIUM(I) COMPLEXES WITH 1,3-DIMETHYLLUMAZINE(DML) - THE CRYSTAL-STRUCTURE OF [(ETA(2)-(O-4,N-5)DML)(ETA(5)-C(5)ME(5))CLRH](PF6), Zeitschrift fur Naturforschung. B, A journal of chemical sciences, 49(11), 1994, pp. 1554-1560
The crystal structure determination of the new rhodium(III)-complex [(
DML)(C(5)Me(5))ClRh](PF6), DML = 1,3-dimethyllumazine, reveals O-4,N-5
coordination of the metal to DML with not very different bond lengths
of 213.0(2) pm (Rh-N) and 219.2(2) pm (Rh-O). This result stands in c
ontrast to the previously reported structure of a cationic dihydrobiop
terin bound to [Mo(O)CL(3)](-) which exhibited a very unsymmetrical ch
elate arrangement. Chemical and electrochemical two-electron reduction
of the Rh(III) complex led to a very labile Rh(I) species (DML)(C(5)M
e(5))Rh which is distinguished by an intense charge transfer band in t
he visible. The results confirm the characterization of DML as a weak
sigma donor/pi acceptor ligand with a rather low-lying pi orbital.