Synthesis, Structure, and Bonding of Bimetallic Bridging Borylene and Boryl Complexes

Abstract

New synthetic route for the synthesis of diruthenium boryl complexes has been established. Thermolysis of an arachno-ruthenaborane, [(Cp*Ru)2B3H8( CS2H)] (1) (Cp* = η 5 -C5Me5) with phenyl acetylene, led to the formation of bridging boryl borylene complex as [(Cp*Ru)2(µ-HBS2CH2-κ 2 B:κ 2 S){µ-B(C6H4)C(CH3)-κ 2 B:κ 2 C}] (2). In parallel to the formation of 2, the reaction also yielded [(Cp*Ru)(μ-H)BH{HC=C(H)Ph}{SC(H)S}] (3a) and [(Cp*Ru)(μ-H)BH( PhC=CH2){SC(H)S}] (3b). To understand the reaction pathways for the formation of 2, we have thermolyzed 1 in toluene that afforded ruthenium bridging bis(boryl) complex, [(Cp*Ru)2(µ-HBS2CH2-κ 2 B:κ 2 S){µ,η 2 :η 2 -SBH}] (4) along with nido-ruthenathiaborane [(Cp*Ru)2(Me)-(S2B2H3)] (5). Nido-5 is structurally and electronically similar with nido-[(Cp + Ru)2( S2C2Ph2)] (Cp + = η 5 -C5Me4Et), which can be generated from the room temperature reaction of [(Cp + Ru)2(μ,η 1 :η 1 -S2)(μ,η 2 :η 2 -S2)] with diphenylacetylene. Thus, nido-5 can be defined as a true mimic of organometallic cluster nido-[(Cp + Ru)2(S2C2Ph2)]. Complex [(Cp*Ru)2(μ,η 1 :η 1 -S2)(μ,η 2 :η 2 -S2)] ( 6) the Cp* analogue of [(Cp + Ru)2(μ,η 1 :η 1 -S2)(μ,η 2 :η 2 -S2)], can be isolated from the reaction of Li[BH2S3] with [Cp*RuCl2]2 along with a diruthenium boryl complex, [(Cp*Ru)2(μ,η 1 :η 1 -S2)(μ-S2BH-κ 1 B:κ 2 S:κ 2 Sʹ)] (7) in which the boryl unit (S2BH) possesses no bulky heterocyclic ligand. Theoretical studies were performed to shed light on the bonding of these borylene and boryl complexes. The theoretical calculations reveal that the stability of these complexes is due to the strong interaction between the borylene and boryl unit with the ruthenium centers.4, 5, 6 and 7. This material is available free of charge via the internet at http://pubs.acs.org.

Stabilization of dichalcogenide ligands in the coordination sphere of a ruthenium system

“…Two {(p-cymene)Ru(Cl)} fragments in 1 are held together through a Ru-Ru single bond (2.959(2) Å). The metal-metal bond distance in 1 is similar to that of arachno-[(Cp*Ru)2B3H8(CS2H)] 10 (2.9738(3) Å) but longer compared to the bridging boryl borylene complex of ruthenium 11 (2.4608(10) Å). The {Ru2SCl} units in 1 are planar and similar to the {Cr2S2Cl} unit in [Cl(CpCr)4(NO)3(μ-S t Bu)2(μ4,η 2 -S2)] 3c .…”

“…The MO analyses of these complexes suggest that the HOMO-LUMO gaps follow the order of 1 < 2 < 2' (0.073 (1), 0.072 (2) and 0.069 eV (2'), Fig. S16) and are considerably smaller as compared to the reported disulfide species [(Cp*Ru)2(μ,η 2 :η 2 -S2)(μ,η 1 :η 1 -S2)] 11 (3.115 eV).…”

“…The Ru1-Ru2 bond distance of 2.7804(5) Å in 5 is shorter as compared to that of another bis-homocubane analogue [(RuCp*)2{μ-Se6(BH)2}] 20 (2.877(4) Å). The average B-S distance in 5 (1.9518 Å) is shorter than the boryl complex [(RuCp*)2(μ-SBHS-κ 1 B:κ 2 S:κ 2 S)(μ,η 1 :η 1 -S2)] 11 (1.8235 Å). Unlike 1,3-bis-homocubane isomer core, the core of 1,4isomer comprising ruthenium, boron and chalcogen atoms are exceptional and therefore 5 is a distinguished entry to the family of bis-homocubane derivatives.…”

“…Unlike 1,3-bis-homocubane isomer core, the core of 1,4isomer comprising ruthenium, boron and chalcogen atoms are exceptional and therefore 5 is a distinguished entry to the family of bis-homocubane derivatives. 16), B2'-S5' 2.02(3), B2'-S8' 1.816 (17), S3-S8' 1.942(5), Ru1-S1' 2.3637 (11), Ru2-S5' 2.39(2); S1'-B2'-S5' 92.5(8), S5'-B2'-S8' 114.0 (10). In order to understand the bonding situation, the DFT based theoretical calculations were performed for 3, 4' and 5' (4' and 5' are the Cp analogues of 4 and 5, respectively).…”

“…4: B1-S1 1.932(5), B1-S5 1.946(11), B1-S7 1.868(6), B2-S2 1.866(13), B2-S3 2.095(12), B2-S6 1.866(14), S1-S2 2.013(2), S5-S6 2.052(14), S4-S7 2.1130(15), Ru1-S1 2.3637(11), Ru1-S3 2.2976(11), Ru1-S4 2.2927(10), Ru2-S3 2.3049(11), Ru2-S4 2.2875(10), Ru2-S5 2.356(12), Ru1-Ru2 2.7804(5), S1-B1-S5 108.8(5), S1-B1-S7 106.6(3), S5-B1-S7 104.8(5). 5: B1-S1' 1.932(5), B1-S5' 1.91(2), B2'-S1' 2.165(16), B2'-S5' 2.02(3), B2'-S8' 1.816(17), S3-S8' 1.942(5), Ru1-S1' 2.3637(11), Ru2-S5' 2.39(2); S1'-B2'-S5' 92.5(8), S5'-B2'-S8' 114.0(10).…”