Ligand Substitution Processes on Carbonylmetal Derivatives. 3.¹Reaction of Hydridopentacarbonylchromates with Phosphines

Abstract

The reaction of K + [HCr(CO) 5 ]with phosphanes PR 3 (R ) Et, Ph, NMe 2 ) in THF at 65 °C affords the disubstituted complexes trans-Cr(CO) 4 (PR 3 ) 2 isolated in 57-70% yield. The X-ray crystal structures of trans-Cr(CO) 4 (PR 3 ) 2 derivatives have been determined for R ) Et and NMe 2 . These reactions proceed first by exchange of one carbon monoxide ligand, generating the monosubstituted hydridotetracarbonylchromates K + [HCr(CO) 4 PR 3 ] -, observed and characterized by NMR spectroscopy for R ) Et and Ph. The second step involves substitution of the hydride ligand of K + [HCr(CO) 4 PR 3 ]to give the disubstituted derivatives trans-Cr(CO) 4 (PR 3 ) 2 . These ligand exchange processes are discussed and compared with the reaction of phosphanes with the dinuclear bridged K + (µ-H)[Cr(CO) 5 ] 2 -.

Zur Reaktivität eines terminalen Chromborylenkomplexes gegenüber Olefinen – Boryleneinschub in eine C‐H‐Bindung

“…Das nichtkoordinierte Vinylboran 2 wurde gemäß Schema analysenrein aus der Mischung von 2 und 3 erhalten. Die Zugabe von zwei Äquivalenten PCy 3 führte zur Freisetzung des Borans und Bildung von [Cr(CO) 4 (PCy 3 ) 2 ] ( 5 ), das ein charakteristisches 31 P‐NMR‐Signal bei δ =69.4 ppm zeigt 14. Das Vinylboran 2 wurde als farblose, luft‐ und feuchtigkeitsempfindliche Flüssigkeit isoliert, die unter Argon bei Raumtemperatur mehrere Wochen unzersetzt gelagert werden konnte.…”

Reactivity of a Terminal Chromium Borylene Complex towards Olefins: Insertion of a Borylene into a CH Bond

“…[11] The C5ÀB1 distance is in the expected range of CÀB single bonds (1.5482(18) ) but is surprisingly unperturbed by the close Cr-H-B association, the distance agreeing well with the vinylborane complex [(OC) 4 Fe{H 2 C = CHBCH 3 N(CH 3 ) 2 }] (4) of Schmid et al, in which the boron atom is distant from the metal center. [12] The B1ÀN1 bond of 3 (1.4034 (16) ) is also within the range of B=N bonds (for example 4, 1.416 (14) ). The close Cr1ÀB1 (2.2996 (13) ) and Cr1-H1 (1.764 (15) ) distances, in addition to the 1 H NMR data, support the idea of B À H s bonding to the metal center, and the overall structure of the H À B À C = C moiety is reminiscent of a distorted cis-butadiene-type ligand, although the BÀC bond does not appear to be involved in the bonding.…”

“…[14] Vinylborane 2 was obtained as a colorless liquid, which is sensitive towards air and moisture but could be stored under argon at room temperature for several weeks without decomposition.…”

trans-Tetracarbonylbis[tris(4-fluorophenyl)phosphane-κP]chromium(0)

“…For the crystal structures of phosphane complexes of carbonylchromium compounds, see: Preston et al (1972); bin Shawkataly et al (1996Shawkataly et al ( , 2009. For related structures, see: Brunet et al (2002); Bennett et al (2004). A search of the Cambridge Structural Database (Allen, 2002) reveals 113 complexes of carbonylchromium complexes with bis-phosphanes.…”

“…The bonding characteristics of metal carbonyls with a phosphane ligand in phosphane-substituted metal carbonyls are interesting. Several crystal structures of phosphane substituted group 6 carbonyls with trans coordination of phosphane are reported (Brunet et al 2002;Bennett et al, 2004).…”