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

Synthesis and characterization of group 6-9 metal-rich homo- and hetero-metallaboranes

International audienceTo isolate the metal-rich metallaboranes of group 6-9, we have performed the reaction of various reaction intermediates, generally synthesized from the low-temperature reactions of [Cp∗WCl4] (Cp∗ ​= ​η5-C5Me5), [(Cp∗RhCl2)2], or [(Cp∗RuCl2)2] and [LiBH4 THF] with different transition metal carbonyl compounds. For example, the thermolytic reaction of [Fe2(CO)9] with an in situ generated intermediate, produced from the reaction of [Cp∗WCl4] and [LiBH4THF] afforded a trigonal bipyramidal cluster, [(μ3-BH)2H2{Cp∗W(CO)2}{Cp∗W(CO)}{Fe(CO)3}], 1 which contains a triply-bridging bis-{hydrido(borylene)} ligand. Similarly, the reaction of [Co2(CO)8] with nido-[(RhCp∗)2(B3H7)] I at room temperature, yielded an octahedral cluster, [(Cp∗Rh)2B2H2Co2(CO)5(μ3-CO)], 2. In this reaction, nido-I having (n+2) skeletal electron pairs (SEP) goes on for the formation of a closo-rhodaborane with (n+1) SEP. In addition, we have isolated a trinuclear bis(μ3-oxo) metalla cluster [(Cp∗Ru)3(μ3-OBF3)2(μ-H)], 3. Compound 3 can be considered as cluster having trigonal bipyramidal geometry with exo-BF3 fragment. All these clusters were characterized by IR, mass spectrometry, NMR, and single-crystal X-ray crystallographic analysis

Heterometallic Triply-Bridging Bis-Borylene Complexes

International audienceTriply-bridging bis-{hydrido(borylene)} and bis-borylene species of groups 6, 8 and 9 transition metals are reported. Mild thermolysis of [Fe-2(CO)(9)] with an in situ produced intermediate, generated from the low-temperature reaction of [Cp*WCl4] (Cp*=eta(5)-C5Me5) and [LiBH4.THF] afforded triply-bridging bis-{hydrido(borylene)}, [(mu(3)-BH)(2)H-2{Cp*W(CO)(2)}(2){Fe(CO)(2)}] (1) and bis-borylene, [(mu(3)-BH)(2){Cp*W(CO)(2)}(2){Fe(CO)(3)}] (2). The chemical bonding analyses of 1 show that the B-H interactions in bis-{hydrido (borylene)} species is stronger as compared to the M-H ones. Frontier molecular orbital analysis shows a significantly larger energy gap between the HOMO-LUMO for 2 as compared to 1. In an attempt to synthesize the ruthenium analogue of 1, a similar reaction has been performed with [Ru-3(CO)(12)]. Although we failed to get the bis-{hydrido(borylene)} species, the reaction afforded triply-bridging bis-borylene species [(mu(3)-BH)(2){WCp*(CO)(2)}(2){Ru(CO)(3)}] (2 '), an analogue of 2. In search for the isolation of bridging bis-borylene species of Rh, we have treated [Co-2(CO)(8)] with nido-[(RhCp*)(2)(B3H7)], which afforded triply-bridging bis-borylene species [(mu(3)-BH)(2)(RhCp*)(2)Co-2(CO)(4)(mu-CO)] (3). All the compounds have been characterized by means of single-crystal X-ray diffraction study; H-1, B-11, C-13 NMR spectroscopy; IR spectroscopy and mass spectrometry

Hydroboration of Alkynes eta(4)-Alkene-Borane versus eta(4)-E-Boratabutadiene

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

International audienceIn 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. Compounds 4 a and 4 b show two different geometries, in which the Rh-B bonds are shorter than in the reported Rh agostic complexes. The new compounds have been characterized in solution by various spectroscopic analyses, and their structural arrangements have been unequivocally established by crystallographic analyses. DFT calculations provide useful insights regarding the stability of these metallaboratrane complexes as well as their M→B bonding interactions

Chalcogen Stabilized bis-Hydridoborate Complexes of Cobalt Analogues of Tetracyclo[4.3.0.02,4.03,5]nonane

International audienceTreatment of Li[BH ER] (E=Se or Te, R=Ph; E=S, R=CH Ph) with [Cp*CoCl] led to the formation of hydridoborate complexes, [{CoCp*Ph}{Cp*Co}{μ-EPh}{μ-κ -E,H-EBH }], 1a and 1 b (1 a: E=Se; 1 b: E=Te) and a bis-hydridoborate species [Cp*Co{μ-κ -Se,H-SeBH }] , 2. All the complexes, 1 a, 1 b and 2 are stabilized by β-agostic type interaction in which 1 b represents a novel bimetallic borate complex with a rare B-Te bond. QTAIM analysis furnished direct proof for the existence of a shared and dative B-chalcogen and Co-chalcogen interactions, respectively. In parallel to the formation of the hydridoborate complexes, the reactions also yielded tetracyclic species, [Cp*Co{κ -E,H,H-E(BH ) -C Me H }], 3 a and 3 b (3 a: E=Se and 3 b: E=S), wherein the bridgehead boron atoms are surrounded by one chalcogen, one cobalt and two carbon atoms of a cyclopentane ring. Molecules 3 a and 3 b are best described as the structural mimic of tetracyclo[4.3.0.0 .0 ]nonane having identical structure and similar valence electron counts