Cooperative B-H bond activation: dual site borane activation by redox active κ-,-chelated complexes.

Cooperative dual site activation of boranes by redox-active 1,3-,-chelated ruthenium species, -[PR{κ-,-(L)}Ru{κ--(L)}], (-2a: R = Cy, -2b: R = Ph; L = NCHS), generated from the aerial oxidation of borate complexes, [PR{κ-,-(L)}Ru{κ-,,'-BH(L)}] (--1a: R = Cy, --1b: R = Ph; L = NCHS), has been investigated. Utilizing the rich electronic behaviour of these 1,3-,-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 -2a-b with BH·THF led to the isolation of -[PRRu{κ-,,'-(NHBSBHN)(SCH)}] (-3a: R = Cy and -3b: R = Ph) that captured boranes at both sites of the κ-,-chelated ruthenacycles.

Cooperative B-H and Si-H Bond Activations by κ-,-Chelated Ruthenium Borate Complexes.

Cooperative E-H (E = B, Si) bond activations employing κ--chelated ruthenium borate species, [PPh{κ--(NSCH)}Ru{κ--HB(NCHS)}], () are established. Treatment of with BH·SMe yielded the six-membered ruthenaheterocycle [PPh{κ--(BHNSCH)}Ru{κ--HB(CHNS)}] () formed by a hemilabile ring opening of a Ru-N bond and capturing of a BH unit coordinated in an "end-on" fashion. On the other hand, the bulky borane HBMes shows different reactivity with that led to the formation of the two dihydroborate complexes [{κ--(NBHMes)(SCH)}Ru{κ--HB(CHNS)}] () and [PPh{κ--(NBHMes)(SCH)}Ru(κ--CHNS)] (), in which HBMes has been inserted into the Ru-N bond of the initial κ--chelated ligand.

A BN-Doped Cycloparaphenylene Debuts.

The first example of a BN-doped cycloparaphenylene BN-[10]CPP was synthesized and characterized. Its reactivity and photophysical properties were evaluated in direct comparison to its carbonaceous analogues Mes-[10]CPP and [10]CPP. While the photophysical properties of BN-[10]CPP remains similar to its carbonaceous analogues, the electronic structure changes associated with the introduction of a 1,2-azaborine BN heterocycle into a CPP scaffold enables facile and selective late-stage functionalizations that cannot be accomplished with carbonaceous CPPs.

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

Room-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.

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

Building 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.

Correction: Mercapto-benzothiazolyl based ruthenium(ii) borate complexes: synthesis and reactivity towards various phosphines.

Correction for 'Mercapto-benzothiazolyl based ruthenium(ii) borate complexes: synthesis and reactivity towards various phosphines' by Mohammad Zafar, et al., Dalton Trans., 2019, DOI: 10.

Mercapto-benzothiazolyl based ruthenium(ii) borate complexes: synthesis and reactivity towards various phosphines.

The synthesis and reactivity of ruthenium complexes containing an anionic boron based ligand, supported by mercapto-benzothiazolyl heterocycles are presented. Specifically, the reaction of [(η-p-cymene)Ru{P(OMe)OR}Cl], (1a: R = Me; 1b: R = H) with [HB(mbz)] (mbz = 2-mercaptobenzothiazolyl) at room temperature afforded a series of borate complexes, namely [(L)Ru{κ-H,S,S'-HB(L)}P(O)(OMe)(HL)], 2, [Ru{κ-H,S,S'-HB(L)}], 3 and [(κ-N,S-L)P(OMe)Ru{κ-H,S,S'-HB(L)}], 4a; (L = CHNS). The pivotal feature of 2 is the coordination of the Ru centre with a phosphorus atom of secondary phosphine oxide and mercapto-benzothiazolyl ligands.

Cluster Fusion: Face-Fused Macropolyhedral Tetracobaltaboranes.

In an effort to isolate the 16-vertex supraicosahedral cobaltaborane [(Cp*Co)BHCo{Cp*CoBH}] (Cp* = η-CMe), we have pyrolyzed an in situ generated intermediate, obtained from the fast metathesis of [Cp*CoCl] and [LiBH·THF], with an excess amount of [BH·THF]. Although the objective of isolating the 16-vertex cobalt analogue was not achieved, the reaction yielded a closo-19-vertex face-fused cluster presenting icosahedral {CoB}, tetrahedral {B}, and 10-vertex {CoB} units. The reaction also yielded a 20-vertex face-fused cluster that contains icosahedral {CoB}, square-pyramidal {CoB}, tetrahedral {CoB}, and nido-{CoB} units.

An Efficient Method for the Synthesis of Boratrane Complexes of Late Transition Metals.

In a quest for efficient precursors for the synthesis of boratrane complexes of late transition metals, we have developed a useful synthetic method using [L'M(μ-Cl)Cl ] as precursors (L'=η -p-cymene, M=Ru, x=1; L'=COD, M=Rh, x=0 and L'=Cp*, M=Ir or Rh, x=1; COD=1,5-cyclooctadiene, Cp*=η -C Me ). For example, treatment of Na[(H B)bbza] or Na[(H B)mp ] (bbza=bis(benzothiazol-2-yl)amine; mp=2-mercaptopyridyl) with [L'M(μ-Cl)Cl ] yielded [(η -p-cymene)RuBH{(NCSC H )(NR)} ] (2; R=NCSC H ), [{N(NCSC H ) }RhBH{(NCSC H )(NR)} ] (3; R=NCS-C H ), [(η -p-cymene)RuBH(L) ] (5; L=C H NS), and [Cp*MBH(L) ] (6 and 7; L=C H NS, M=Ir or Rh). In order to delineate the significance of the ligands, we studied the reactivity of [(COD)Rh(μ-Cl)] with Na[(H B)bbza], which led to the formation of the isomeric agostic complexes [(η -COD)Rh(μ-H)BHRh(C H N S ) ], 4 a and 4 b, in parallel to the formation of 16-electron square-pyramidal rhodaboratrane complex 3.

Design, Synthesis, and Chemistry of Bis(σ)borate and Agostic Complexes of Group 7 Metals.

A series of new bis(σ)borate and agostic complexes of group 7 metals have been synthesized and structurally characterized from various borate ligands, such as trihydrobis(benzothiazol-2-yl)amideborate (Na[(H B)bbza]), trihydro(2-aminobenzothiazolyl)borate (Na[(H B)abz]), and dihydrobis(2-mercaptopyridyl)borate (Na[(H B)mp ]) (bbza=bis(benzothiazol-2-yl)amine, abz=2-aminobenzothiazolyl, and mp=2-mercaptopyridyl). Photolysis of [Mn (CO) ] with Na[(H B)bbza] formed bis(σ)borate complex [Mn(CO) (μ-H) BHNCSC H (NR)] (1; R=NCSC H ). Octahedral complex [Re(CO) (N C S C H ) ] (2) was generated under similar reaction conditions with [Re (CO) ].

Reactivity of cyclopentadienyl transition metal(ii) complexes with borate ligands: structural characterization of the toluene-activated molybdenum complex [Cp*Mo(CO)(η-CHCH)].

Reactions of cyclopentadienyl transition-metal halide complexes [Cp*Mo(CO)Cl], 1, and [CpFe(CO)I], 2, (Cp = CH; Cp* = η-CMe) with borate ligands are reported. Treatment of 1 with [NaBt] (Bt = dihydrobis(2-mercapto-benzothiazolyl)borate) in toluene yielded [Cp*Mo(CO)(CHSN)], 3, and [Cp*Mo(CO)(η-CHCH)], 4, with a selective binding of toluene through C-H activation followed by orthometallation. Note that compound 4 is a structurally characterized toluene-activated molecule in which the metal is in η-coordination mode.

η(4) -HBCC-σ,π-Borataallyl Complexes of Ruthenium Comprising an Agostic Interaction.

Thermolysis of [Cp*Ru(PPh2 (CH2 )PPh2 )BH2 (L2 )] 1 (Cp*=η(5) -C5 Me5 ; L=C7 H4 NS2 ), with terminal alkynes led to the formation of η(4) -σ,π-borataallyl complexes [Cp*Ru(μ-H)B{R-C=CH2 }(L)2 ] (2 a-c) and η(2) -vinylborane complexes [Cp*Ru(R-C=CH2 )BH(L)2 ] (3 a-c) (2 a, 3 a: R=Ph; 2 b, 3 b: R=COOCH3 ; 2 c, 3 c: R=p-CH3 -C6 H4 ; L=C7 H4 NS2 ) through hydroboration reaction. Ruthenium and the HBCC unit of the vinylborane moiety in 2 a-c are linked by a unique η(4) -interaction. Conversions of 1 into 3 a-c proceed through the formation of intermediates 2 a-c.

New Routes to a Series of σ-Borane/Borate Complexes of Molybdenum and Ruthenium.

A series of agostic σ-borane/borate complexes have been synthesized and structurally characterized from simple borane adducts. A room-temperature reaction of [Cp*Mo(CO)3 Me], 1 with Li[BH3 (EPh)] (Cp*=pentamethylcyclopentadienyl, E=S, Se, Te) yielded hydroborate complexes [Cp*Mo(CO)2 (μ-H)BH2 EPh] in good yields. With 2-mercapto-benzothiazole, an N,S-carbene-anchored σ-borate complex [Cp*Mo(CO)2 BH3 (1-benzothiazol-2-ylidene)] (5) was isolated.

First-row transition-metal-diborane and -borylene complexes.

A combined experimental and quantum chemical study of Group 7 borane, trimetallic triply bridged borylene and boride complexes has been undertaken. Treatment of [{Cp*CoCl}2 ] (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) with LiBH4 ⋅thf at -78 °C, followed by room-temperature reaction with three equivalents of [Mn2 (CO)10 ] yielded a manganese hexahydridodiborate compound [{(OC)4 Mn}(η(6) -B2 H6 ){Mn(CO)3 }2 (μ-H)] (1) and a triply bridged borylene complex [(μ3 -BH)(Cp*Co)2 (μ-CO)(μ-H)2 MnH(CO)3 ] (2). In a similar fashion, [Re2 (CO)10 ] generated [(μ3 -BH)(Cp*Co)2 (μ-CO)(μ-H)2 ReH(CO)3 ] (3) and [(μ3 -BH)(Cp*Co)2 (μ-CO)2 (μ-H)Co(CO)3 ] (4) in modest yields.

Synthesis, characterization and crystal structure analysis of cobaltaborane and cobaltaheteroborane clusters.

Cluster expansion reactions of cobaltaboranes were carried out using mono metal-carbonyls, metal halides and dichalcogenide ligands. Thermolysis of an in situ generated intermediate, obtained from the reaction of [Cp*CoCl]2 (Cp* = C5Me5) and [LiBH4·thf], with three equivalents of [Mo(CO)3(CH3CN)3] followed by the reaction with methyl iodide yielded isocloso-[(Cp*Co)3B6H7Co(CO)2] (1) and closo-[(Cp*Co)2B2H5Mo2(CO)6I] (2). Cluster 1 is ascribed to the isocloso structure based on a 10-vertex bicapped square antiprism geometry.

New heteronuclear bridged borylene complexes that were derived from [{Cp*CoCl}2] and mono-metal-carbonyl fragments.

The synthesis, structural characterization, and reactivity of new bridged borylene complexes are reported. The reaction of [{Cp*CoCl}2] with LiBH4·THF at -70 °C, followed by treatment with [M(CO)3(MeCN)3] (M=W, Mo, and Cr) under mild conditions, yielded heteronuclear triply bridged borylene complexes, [(μ3-BH)(Cp*Co)2(μ-CO)M(CO)5] (1-3; 1: M=W, 2: M=Mo, 3: M=Cr). During the syntheses of complexes 1-3, capped-octahedral cluster [(Cp*Co)2(μ-H)(BH)4{Co(CO)2}] (4) was also isolated in good yield.