Tri-N-pyrrolylsilyl complexes of ruthenium and osmium

Article abstract of DOI:10.1021/om970044p

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 gives the six-coordinate compounds M(SiPyr₃)H(CO)₂(PPh₃)₂ (Pyr = 1-NC₄H₄; 2a, M = Ru; 2b, M = Os), whereas overall phenyl group-silyl group exchange between MPhCl(CO)(PPh₃)₂ and 1 yields the five-coordinate species M(SiPyr₃)Cl(CO)(PPh₃)₂ (3a, M = Ru; 3b, M = Os). The nitrosyl complex Os(SiPyr₃)HCl(NO)(PPh₃)₂ (4) can be prepared from OsCl(NO)(PPh₃)₃ and 1. The carbonyl groups in these compounds show relatively high C-O stretching frequencies, which fall between those found for the trihydroxysilyl and trichlorosilyl analogues. Bond lengths and angles obtained from the X-ray structure determinations of HSiPyr₃ (1) and Os(SiPyr₃)H(CO)₂(PPh₃)₂ (2b) indicate that the SiPyr₃ moiety undergoes significant changes on coordination to osmium.