Dimetallaheteroborane clusters containing group 16 elements: A combined experimental and theoretical study

Recently we described the synthesis and structural characterization of various dimetallaherteroborane clusters, namely nido-[(Cp∗Mo2B4EClxH6−x], 1–3; (1: E = S, x = 0; 2: E = Se, x = 0; 3: E = Te, x = 1). A combined theoretical and experimental study was also performed, which demonstrated that the clusters 1–3 with their open face are excellent precursors for cluster growth reaction. In this investigation process on the reactivity of dimetallaheteroboranes with metal carbonyls, in addition to [(Cp∗Mo)2B4H6EFe(CO)3] (4: E = S, 6: E = Te) reported earlier, reaction of 2 with [ Fe2(CO)9] yielded mixed-metallaselenaborane [(Cp∗Mo)2B4H6SeFe(CO)3], 5 in good yield. The quantum chemical calculation using DFT method has been carried out to probe the bonding, NMR chemical shifts and electronic properties of dimolybdaheteroborane clusters 4–6

Reactivity of [Cp*Mo(CO)₃Me] with chalcogenated borohydrides Li[BH₂E₃] and Li[BH₃EFc] (Cp*= (η⁵-C₅Me₅); E = S, Se or Te; Fc = (C₅H₅-Fe-C₅H₄))

Reactivity of [Cp*Mo(CO)3Me], 1 with various chalcogenide ligands such as Li[BH2E3] and Li[BH3EFc] (E = S, Se or Te; Fc = (C5H5-Fe-C5H4)) has been described. Room temperature reaction of 1 with Li[BH2E3] (E = S and Se) yielded metal chalcogenide complexes [Cp*Mo(CO)2(η2-S2CCH3)], 2 and [Cp*Mo(CO)2(η1-SeC2H5)], 3. In compound 2, {Cp*Mo(CO)2} fragment adopts a four-legged piano-stool geometry with a η2-dithioacetate moiety. In contrast, treatment of 1 with Li[BH3(EFc)] (E = S, Se or Te; Fc = C5H5-Fe-C5H4) yielded borate complexes [Cp*Mo(CO)2(μ-H)(μ-EFc)BH2], 4-6 in moderate yields. Compounds 4-6 are too unstable and gradual conversion to [{Cp*Mo(CO)2}2(μ-H)(μ-EFc] (7: E = S; 8: Se) and [{Cp*Mo(CO)2}2 (μ-TeFc)2], 9 happened by subsequent release of BH 3. All the compounds have been characterized by mass spectrometry, IR, multinuclear NMR spectroscopy and structures were unequivocally established by crystallographic analysis for compounds 2, 3 and 7

Synthesis, structure and chemistry of low-boron containing molybdaborane: Arachno-[Cp*Mo(CO)₂B₃H₈]

Room temperature photolysis of [Cp*Mo(CO)₃Me], 1 with excess of [BH₃·THF] led to the isolation of hydrogen-rich arachno-[Cp*Mo(CO)₂B₃H₈], 2 in good yield. The geometry of arachno-2 consists of a butterfly core similar to that of 7 skeletal electron pairs tetraborane(10). Further, the metal fragment addition reaction of arachno-2 with [Fe₂(CO)₉] yielded a nido-[Cp*Mo(CO)₂B₃H₆Fe(CO)₃], 3 that plays a pivotal role in bringing a change in the geometry from arachno-2 to nido-3. The reaction of arachno-2 with [Ru₃(CO)₁₂], however, yielded known metal carbonyl compound [Cp*Mo(CO)₃]₂, 4. All the new compounds have been characterized in solution by mass spectrometry, IR, ¹H, ¹¹B, ¹³C NMR spectroscopy and the solid state X-ray structures of 2 and 3 were unequivocally established by X-ray diffraction analysis. Additionally, we have studied the bonding nature of compounds 2 and 3 with the help of density functional theory (DFT) calculations

Neutral heterometallic cluster containing ketenylidene ligand: [Cp*Mo(CO)₂(μ-H)Ru₂(CO)₆(μ₃-ɳ¹-CCO)] (Cp* = ɳ⁵-C₅Me₅)

Building upon our earlier work on low-boron containing molybdaborane arachno-[Cp*Mo(CO)2B3H8], 1 we continue to investigate the reactivity of the same system with group 8 metal carbonyl compounds. As a result, thermolysis of arachno-1 in presence of [Ru3(CO)12] led to the formation of neutral heterometallic ketenylidene cluster [Cp*Mo(CO)2(μ-H)Ru2(CO)6(μ3-ɳ1-CCO)], 2, in which the triply bridged ketenylidene fragment (CCO) is lying perpendicular to the plane of the metal triangle (Ru–Mo–Ru). In addition to the formation of cluster 2, the reaction also yielded a semi-interstitial boride cluster [Cp*Mo(CO)2{Ru(CO)3}4B], 3 and a known bimetallic cluster [Cp*Mo(CO)3]2, 4 in moderate yields. The geometry of 3 can be described as a square pyramidal, in which the boron atom caps the square face formed by three Ru and one Mo atoms respectively. All the new compounds have been characterized by multinuclear NMR spectroscopy, IR spectroscopy and mass spectrometry. In addition to these, the solid state structure of 2 and 3 were unequivocally established by single crystal X-ray diffraction analysis

Synthesis and structural characterization of trithiocarbonate complexes of molybdenum and ruthenium derived from CS2 ligand

International audienceIn an effort to synthesize trithiocarbonate complexes of molybdenum and ruthenium, we carried out the reaction of CS2 with the intermediates, obtained from the reaction of [(CpML3X)-M-#], (1: Cp-# = C5Me5, M = Mo, L-1 = L-2 = L-3 = CO, X = Me; 2: Cp-# = C5H5, M = Ru, L-1 = L-2 = PPh3, X = Cl and 3: Cp-# = C5H5, M = Fe, L-1 = L-2 = CO, X = I) and [LiBH4 center dot thf]. The reactions led to formation of the trithiocarbonate complexes [Cp*Mo(CO)(2)(mu-eta(2):eta(1)-CS3)(CO)(3)MoCp*] (4) [Cp*Mo(CO)(2)(eta(2)-S2CSMe)] (5) and [Cp*Mo(-CO)(2)(eta(2)-S2CMe)] (6) in moderate yields. Treatment of [CpRu(PPh3)(2)Cl] (2) with [LiBH4 center dot thf] followed by mild pyrolysis of CS2 yielded the trithiocarbonate ruthenium complex [CpRuPPh3(eta(2)-S2CSMe)] (7). All the new compounds have been characterized by various spectroscopic techniques and the structures of compounds 4, 5 and 7 were unequivocally established by crystallographic analysis. (C) 2017 Published by Elsevier B.V

Homocubane Chemistry: Synthesis and Structures of Mono- and Dicobaltaheteroborane Analogues of Tris- and Tetrahomocubanes

International audienceRoom-temperature reactions between [Cp*CoCl] (Cp* = η-CMe) and large excess of [BHE]Li (E = S or Se) led to the formation of homocubane derivatives, . These species are bimetallic tetrahomocubane, [(Cp*Co)(μ-S)(μ-S)BH], ; bimetallic trishomocubane isomers, [(Cp*Co)(μ-S)(μ-S)BH], and ; monometallic trishomocubanes, [M(μ-E)(μ-E)BH] [: M = Cp*Co, E = S; : M = Cp*Co, E = Se and : M = {(Cp*Co)(μ-H)(μ-Se)}Co, E = Se], and bimetallic homocubane, [(Cp*Co)(μ-Se)(μ-Se)BH], . As per our knowledge, is the first isolated and structurally characterized parent prototype of the 1,2,2',4 isomer of tetrahomocubane, while , , and are the analogues of parent -trishomocubane. Compounds and are the structural isomers in which the positions of the μ-S ligands in the trishomocubane framework are altered. Compound is an example of a unique vertex-fused trishomocubane derivative, in which the -trishomocubane [Co(μ-Se)(μ-Se)BH] moiety is fused with an exopolyhedral trigonal bipyramid (tbp) moiety [(Cp*Co)(μ-H)(μ-Se)}Co]. Multinuclear NMR and infrared spectroscopy, mass spectrometry, and single crystal X-ray diffraction analyses were employed to characterize all the compounds in solution. Bonding in these homocubane analogues has been elucidated computationally by density functional theory methods

Synthesis and structural characterization of group 7 and 8 metal-thiolate complexes

Thermolysis of [Cp*Ru(µ-H)BH(L)2] (Cp* = η5-C5Me5, L = C7H4NS2), (1) with [Mn2(CO)10] led to the formation of a transmetallated complex [Mn(CO)3(µ-H)BH(L)2], (2) and a ruthenium-thiolate complex [(Cp*RuCO)2(L)2], (3) in moderate yields. Compound 2 can also be generated from a direct reaction of [Mn2(CO)10] and [NaBt] (Bt = dihydrobis(2-mercaptobenzthiazolyl)borate). Although all of our attempts to generate [M(CO)3(µ-H)2BHL] (M = Mn or Re) from the bis(σ-borate) complex [Cp*Ru(µ-H)2BHL] (L = C7H4NS2), (4) were failed, thermolysis of 4 with [Mn2(CO)10] yielded a σ-borane complex [Cp*RuCO(µ-H)BH2L], (5) and a mixed-metal thiolate complex [(Cp*RuCO)2 (µ3-S)Mn(CO)3L], (6). Further, the reaction of compound 5 with [Mn2(CO)10] yielded heterocyclic thiolate complex [Cp*Ru(CO)2L)], (7). Thermolysis of 4 with [Re2(CO)10] does not yield any products. However, under photolytic conditions it led to the formation of mixed-metal thiolate complex [(Cp*RuCO)Re(CO)3 (L)2], (8). All the compounds have been characterized by mass spectrometry, IR, 1H, 13C spectroscopy, and the X-ray structures of 2–3 and 5–8 were unequivocally established by crystallographic analysis

Five-Membered Ruthenacycles Ligand-Assisted Alkyne Insertion into 1,3-N,S-Chelated Ruthenium Borate Species

International audienceBuilding upon previous work, the chemistry of [(η -p-cymene)Ru{P(OMe) OR}Cl ], (R=H or Me) has been extended with [H B(mbz) ] (mbz=2-mercaptobenzothiazolyl) using different Ru precursors and borate ligands. As a result, a series of 1,3-N,S-chelated ruthenium borate complexes, for example, [(κ -N,S-L)PR Ru{κ -H,S,S'-H B(L) }], (2 a-d and 2 a'-d'; R=Ph, Cy, OMe or OPh and L=C H NS or C H NS ) and [Ru{κ -H,S,S'-H B(L) } ], (3 L=C H NS, 3' L=C H NS ) were isolated upon treatment of [(η -p-cymene)RuCl PR ], 1 a-d (R=Ph, Cy, OMe or OPh) with [H B(mp) ] or [H B(mbz) ] ligands (mp=2-mercaptopyridyl). All the Ru borate complexes, 2 a-d and 2 a'-d' are stabilized by phosphine/phosphite and hemilabile N,S-chelating ligands. Treatment of these Ru borate species, 2 a'-c' with various terminal alkynes yielded two different types of five-membered ruthenacycle species, namely [PR {C H S -(E)-N-C=CH(R')}Ru{κ -H,S,S'-H B(L) }], (4-4'; R=Ph and R'=CO Me or C H NO ; L=C H NS ) and [PR {C H NS-(E)-S-C=CH(R')}Ru{κ -H,S,S'-H B(L) }], (5-5', 6 and 7; R=Ph, Cy or OMe and R'=CO Me or C H NO ; L=C H NS ). All these five-membered ruthenacycle species contain an exocyclic C=C moiety, presumably formed by the insertion of a terminal alkyne into the Ru-N and Ru-S bonds. The new species have been characterized spectroscopically and the structures were further confirmed by single-crystal X-ray diffraction analysis. Theoretical studies and chemical-bonding analyses established that charge transfer occurs from phosphorus to ruthenium center following the trend PCy <PPh <P(OPh) <P(OMe)

Cooperative B-H bond activation: dual site borane activation by redox active kappa(2)-N,S-chelated complexes

International audienceCooperative dual site activation of boranes by redox-active 1,3-N,S-chelated ruthenium species, mer-[PR3{kappa(2)-N,S-(L)}(2)Ru{kappa(1)-S-(L)}], (mer-2a: R = Cy, mer-2b: R = Ph; L = NC7H4S2), generated from the aerial oxidation of borate complexes, [PR3{kappa(2)-N,S-(L)}Ru{kappa(3)-H,S,S '-BH2(L)(2)}] (trans-mer-1a: R = Cy, trans-mer-1b: R = Ph; L = NC7H4S2), has been investigated. Utilizing the rich electronic behaviour of these 1,3-N,S-chelated ruthenium species, we have established that a combination of redox-active ligands and metal-ligand cooperativity has a big influence on the multisite borane activation. For example, treatment of mer-2a-b with BH3 center dot THF led to the isolation of fac-[PR3Ru{kappa(3)-H,S,S '-(NH2BSBH2N)(S2C7H4)(2)}] (fac-3a: R = Cy and fac-3b: R = Ph) that captured boranes at both sites of the kappa(2)-N,S-chelated ruthenacycles. The core structure of fac-3a and fac-3b consists of two five-membered ruthenacycles [RuBNCS] which are fused by one butterfly moiety [RuB2S]. Analogous fac-3c, [PPh3Ru{kappa(3)-H,S,S '-(NH2BSBH2N)(SC5H4)(2)}], can also be synthesized from the reaction of BH3 center dot THF with [PPh3{kappa(2)-N,S-(SNC5H4)}{kappa(3)-H,S,S '-BH2(SNH4C5)(2)}Ru], cis-fac-1c. In stark contrast, when mer-2b was treated with BH(2)Mes (Mes = 2,4,6-trimethyl phenyl) it led to the formation of trans- and cis-bis(dihydroborate) complexes [{kappa(3)-S,H,H-(NH(2)BMes)Ru(S2C7H4)}(2)], (trans-4 and cis-4). Both the complexes have two five-membered [Ru-(H)(2)-B-NCS] ruthenacycles with kappa(2)-H-H coordination modes. Density functional theory (DFT) calculations suggest that the activation of boranes across the dual Ru-N site is more facile than the Ru-S one