A new synthetic route to pentacarbonylalkene complexes of tungsten(0): X-ray crystal structure of [W(CO)5(η2-C2H4)]

Amino-Substituted Butatrienes: Unusual η1 Ligands Formed by an Unusual Reaction

“…These bond lengths agree well with those in the starting allenylidene complex 1 (1.348 (6) Å) . When all these structural features are considered, complex 3 is best described as an adduct of a π-donor-stabilized carbene to the C α atom of the allenylidene ligand, comparable to C α phosphine adducts. , …”

“…For olefinic type bonding a shift of the ν(CO) absorptions toward higher wavenumbers was to be expected. Exclusion of π bonding was also supported by a comparison of the 13 C NMR data with those reported by Werner et al for η 2 -butatriene rhodium complexes on the one hand and with those of pentacarbonyl olefin complexes on the other hand . The 13 C NMR data, however, are related to those complexes obtained by addition of phosphines to the C α atom of [(CO) 5 MCCC(aryl) 2 ], [(CO) 5 WCCC(NMe 2 )Ph] ( 16 , see below), or of other transition metals, indicating strongly dipolar character of the new compounds and η 1 coordination of the new ligand as shown in Scheme .…”

“…The W−CO(trans) distance is significantly longer than the average of the W−CO(cis) distances, confirming the pronounced donor capacity of the butatriene ligand already deduced from the IR spectra. The W−C6 bond (2.318(5) Å) is considerably longer than in the starting complex 1 (2.185(8) Å) but is significantly shorter than the corresponding W−C bonds in [(CO) 5 W(olefin)] complexes (2.37−2.53 Å) and slightly shorter than in anionic alkyl pentacarbonyl complexes (2.31−2.40 Å) or neutral dipolar [(CO) 5 W−L] complexes with an W−C(sp 3 ) bond (2.32−2.40 Å) . The W1···C7 and W1···C13 distances are 3.241 and 3.233 Å, respectively.…”

Small-Molecule Activation within the Group 6 Complexes (η5-C5Me5)[N(iPr)C(Me)N(iPr)]M(CO)(L) for M = Mo, W and L = N2, NCMe, η2-Alkene, SMe2, C3H6O

“…Figure presents the solid-state molecular structures of the series of molybdenum derivatives 8 , 10 , 13 , and 14 , and Table presents a correlation of M–C and C–C bond lengths for the η 2 -alkene ligand and the ν CO stretching frequencies for the CO group for these compounds along with the tungsten derivatives 9 and 11 . To begin, it is important to note that reports of structurally characterized second- and third-row group 6 M­(II,d 4 ) carbonyl, η 2 -alkene complexes are extremely rare. − In the present work, all of the Cp*­[N­( i Pr)­C­(Me)­N­( i Pr)]­M­(CO)­(η 2 -alkene) derivatives of II are diamagnetic, thermally stable complexes in solution and do not display any evidence of dynamic rotation about a centralized M–alkene bond axis at room temperature by 1 H NMR spectroscopy. In keeping with these observations, the metal–carbon and carbon–carbon bond lengths associated with the M–(η 2 -alkene) bonding interaction are consistent with a metallacyclopropane resonance structure in which a large degree of π back-donation of electron density from the metal into the π* C–C antibonding orbital exists (see Table ).…”

Synthesis and Reactivity of Group 6 Metal Carbonyl Complexes with Bis(pyrazol‐1‐yl)methanes Modified by the Vinyltin Groups

“…3 On the other hand, group 6 metal carbonyl complexes with the olefinic ligand have attracted considerable attention in the past few decades due to their wide applications to organometallic and catalytic chemistry. [6][7][8][9][10] The carbon-carbon double bond in these complexes displays high reactivity to various electrophilic and nucleophilic reagents because of the coordination of the olefin to transition metals. It is also known that organotin compounds containing unsaturated organic groups show interesting reactivities and structural features.…”