Silicon-transition metal chemistry. 9. Synthesis, properties, and structure of the rhenium acylsilane complex fac-Re(CO)3(diphos)[C(O)SiPh3]

Abstract

Silicon-Transition Metal Chemistry lower temperatures and that their exchange between the apical and equatorial sites of a trigonal bipyramid is rapid above this temperature.The mass spectra (Table II) show a weak or nondetectable molecular ion. The fragments corresponding to the loss of F and OR are important. It is noteworthy that the loss of OR is generally extensive, while the loss of R is not detected; this is tiie opposite to what has been observed previously in the case of the analogous monoalkoxyfluorophenyl(or methyl)phosphoranes, for which the breaking of the OR bond was an important feature.4 The infrared spectra show the expected pas(P-F) bands in the range of 920-800 cm-1. These relatively low values are consistent with apical fluorines in a trigonal-bipyramidal structure10 and comparable to those found in series of compounds R3PF2 having strongly electroattracting R groups.11The P-O-C linkage gives rise to three absorption bands near 1130, 1020, and 780 cm"1 12. The Ph-P linkage produces a characteristic vibration near 1450 cm"1.12 No vibrations assignable to i/(P=0) stretching vibrations were detected.

Synthetic, Spectroscopic, and Electrochemical Studies of the Isomerically-Rich [M(CO)2(P2P‘)X]+/0(M = Mn, Re; X = Cl, Br; P2P‘ = η3-Ph2P(CH2)2P(Ph)(CH2)2PPh2) System: Structural Characterization of a Novel Pair of Diastereoisomers ofcis,mer-Re(CO)2(P2P‘)Cl

“…The Re−P bond lengths are similar and agree with values from previous structure determinations, as do the Re−Cl and Re−C bond lengths. − The nature of the ligand trans to the metal−CO and metal−P bonds is known to influence these bond distances. The Re−C bond of a carbonyl ligand trans to a phosphorus is expected to be longer than Re−C bonds in which the carbonyl is trans to a chlorine atom, since phosphorus has some π-bonding ability, but the metal−halogen bond is regarded as predominantly σ in nature.…”

Synthetic and Computational Studies of Thiocarbonyl/σ-Organyl Coupling Reactions

“…While both of these species react with carbon monoxide to provide thioacyl complexes, the latter example described by Roper is remarkable in that silyl groups are characteristically not prone to such processes. With the exception of early transition metal (d 0 ) sila-acyl complexes reported by Tilley that result from the carbonylation of the corresponding silyl complexes, sila-acyls are in general only accessible via external nucleophilic attack by silyl anions on coordinated CO, , typically as intermediates en route to silylcarbenes and carbynes . Thus the high propensity of thiocarbonyl ligands for migratory insertion processes is emphatically illustrated, though the formation of a Ru−S bond in adopting the bidentate coordination mode no doubt contributes to the thermodynamic impetus.…”

Technetium and Rhenium

“…In a related manner, a substituted triphenylsilyl rhenium complex has been prepared by decarbonylation of a silyl acyl species 302 (E = Si, Ge) have shown these species to exhibit a distorted octahedral geometry with the four radial carbonyl moieties being displaced towards the ER 3 group by some 4-7°.…”