TRI-N-PYRROLYLSILYL COMPLEXES OF RUTHENIUM AND OSMIUM

The development of a new, simple synthesis of tri-N-pyrrolylsilane (1) from trichlorosilane and pyrrole provides a convenient starting point for a series of interesting transition-metal complexes with the tri-N -pyrrolylsilyl ligand, Oxidative addition of 1 to M(CO)(2)(PPh3)(3) gi ves the six-coordinate compounds M(SiPyr(3))H(CO)(2)(PPh3)(2) (Pyr = 1 -NC4H4; 2a, M = Ru; 2b, M = Os), whereas overall phenyl group-silyl gr oup exchange between MPhCl(CO)(PPh3)(2) and 1 yields the five-coordina te species M(SiPyr(3))Cl(CO)(PPh3)(2) (3a, M = Ru; 3b, M = Os). The ni trosyl complex Os(SiPyr(3))HCl(NO)(PPh3)(2) (4) can be prepared from O sCl(NO)(PPh3)(3) and 1. The carbonyl groups in these compounds show re latively high C-O stretching frequencies, which fall between those fou nd for the trihydroxysilyl and trichlorosilyl analogues. Bond lengths and angles obtained from the X-ray structure determinations of HSiPyr( 3) (1) and Os(SiPyr(3))H(CO)(2)(PPh3)(2) (2b) indicate that the SiPyr( 3) moiety undergoes significant changes on coordination to osmium.