Five-Coordinate Ruthenium(II) and Osmium(II) Boryl Complexes

Abstract

The five-coordinate ruthenium boryl complexes, Ru(BR2)Cl(CE)(PPh3)2 (E = O, BR2 = BO2C6H4 (1a); E = O, BR2 = BO2C10H6 (1b); E = O, BR2= B(NH)2C6H4 (1d); E = O, BR2 = B(NH)SC6H4 (1e); E = S, BR2 = BO2C6H4 (2a); E = S, BR2 = B(NH)SC6H4 (2e); E = N-p-tolyl, BR2 = BO2C6H4 (3a)), result from the reactions of RuHCl(CE)(PPh3)3 with the appropriate borane. Related osmium compounds, Os(BR2)Cl(CE)(PPh3)2 (E = O, BR2 = BO2C6H4 (4a); E = O, BR2 = BO2C6H3CH3 (4c); E = O, BR2 = B(NH)2C6H4 (4d); E = O, BR2 = B(NH)SC6H4 (4e); E = S, BR2 = BO2C6H4 (5a)), cannot be prepared from the hydrides but are formed from reactions between Os(Ph)Cl(CE)(PPh3)2 and the appropriate borane. A boryl complex of ruthenium of formula Ru(BO2C6H4)Cl(PPh3)2·H2O (6) results from reaction of RuHCl(PPh3)3 with HBO2C6H4 (catecholborane). IR, 1H NMR, and 13C NMR data for the new boryl complexes are reported.

Boryl-Dihydrideborate Osmium Complexes: Preparation, Structure, and Dynamic Behavior in Solution

“…The osmium-boryl bond length of 2.076(3) Å (Os−B2) compares well with those reported for other osmium-boryl derivatives 22. …”

Transition Metal−Boryl Compounds: Synthesis, Reactivity, and Structure

“…A number of ruthenium-and osmium-boryl species have also been prepared from the reaction between the respective HBR 2 and either a ruthenium-hydride (eq 18) or phenyl-osmium complex (eq 19). 75 Studies involving early transition metal complexes with boranes have been reported to be independent of metal-boryl formation in catalytic processes and sometimes result in the formation of hydridoborate compounds. 47,50,54,[56][57][58][59][60][61] Hartwig and De Gala 47 reported that the reaction of [Cp 2 NbH 3 ] with catecholborane or 9-borabicyclononane (9-BBN) yielded 1 equiv of hydrogen gas as well as the metal-boryl compound, [Cp 2 NbH 2 (Bcat)], or the hydridoborate compound, [Cp 2 Nb{BH 2 (C 8 H 14 )} 2 ], respectively; the latter compound may not necessarily be formed via an oxidative addition mechanism.…”

The Sting of the Scorpion: A Metallaboratrane

“…[13] An elegantly designed cryptand that is highly sensitive and selective for binding NH 4 has been reported. The ruthenium ± boron bond of 2.161(5) is without precedent for comparison, but falls within the range (2.046(7) ± 2.20(2) ) found in osmium ± s-boryl complexes, [8,9] which contain an OsÀB pbonding component, but none of the ring strain that must be accommodated in the tricyclic structure of 4. One of the three Ru À S bond lengths, the one that is trans to the carbonyl group (that is, adjacent to the bulky phosphane) is, as expected, significantly longer (2.4857 (14) ) than the pair of mutually trans RuÀS bonds (RuÀS(1) 2.4066(14), RuÀS(2) 2.4112 (14) ).…”

“…In this context, the elegant synthesis of ruthenium ± sboryl complexes by Roper and Wright et al through the reactions of [Ru(C 6 H 5 )Cl(CO)(PPh 3 ) 2 ] with boranes [8,9] provides compelling support for the proposed mechanism. Dissociation of one mt arm followed by agostic B À H coordination and ultimate oxidative addition of the BÀH bond could provide a cis-hydrido ± vinyl complex that undergoes alkene reductive elimination with formation of 4.…”