Two routes for the synthesis of mer-W(CO)(H)(NO)(PMe3)3 (4) are described, starting from
mer-W(Cl)(CO)(NO)(PMe3)3 (1) or the borohydride complex mer-W(η
1-BH4)(CO)(NO)(PMe3)3
(3). The propensity of 4 to undergo insertion reactions has been investigated. 4 reacts with
benzaldehyde, propionaldehyde, pivalaldehyde, benzophenone, acetophenone, and acetone
to afford the corresponding alkoxide complexes mer-W(CO)(NO)(PMe3)3(OCHR‘R‘ ‘) (R‘ = H,
R‘ ‘ = Ph (5a); R‘ = H, R‘ ‘ = CH2CH2CH3 (5b); R‘ = H, R‘ ‘ = CH2C(CH3)3 (5c); R‘ = Ph, R‘ ‘
= Ph (5d); R‘ = CH3, R‘ ‘ = Ph (5e); R‘ = CH3, R‘ ‘ = CH3 (5f)). Insertion of CO2 yields the
formato-O complex mer-W(CO)(NO)(OCHO)(PMe3)3 (6). Reaction of 4 with CO leads to
immediate loss of PMe3 and formation of trans,trans-W(CO)2(H)(NO)(PMe3)2. In a reversible
way Fe(CO)5 and Re2(CO)10 insert into the W−H bond of 4, affording the isolable μ-formyl
complex mer-W(CO)(NO)(PMe3)3[(μ-OCH)Fe(CO)4] (7a) and mer-W(CO)(NO)(PMe3)3[(μ-OCH)Re2(CO)9] (7b) as an equilibrium constituent. For both reactions equilibrium constants have
been derived from VT-NMR measurements and ΔH values were calculated (−46 kJ/mol for
7a and −26 kJ/mol for 7b). An accompanying DFT analysis of the W−H bond demonstrated
that a higher number of phosphine ligands in a W(CO)4
-
n
(H)(NO)(PMe3)
n
series increases
the hydridic character of the H ligand and induces a stronger bond polarization. The relative
ΔH values for the insertions of the metal carbonyls with n = 3 could be reproduced. The
calculations also suggest that the main difference in the reactivity of Fe(CO)5 and Re2(CO)10
is not primarily an electronic effect but, rather, is due to steric influence. Compounds 3, 4,
6, and 7a were structurally characterized by X-ray diffraction studies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.