A series of hydroborated η4-σ,π-alkene-borane complexes have been synthesized from the reaction of ruthenium-bis(σ)borate complex [Cp∗Ru(μ-H)2BH(S-CH=S)] (1) and terminal as well as internal alkynes. Likewise, the reactions of manganese-bis(σ)borate complexes [Mn(CO)3(μ-H)2BHNCSC6H4(NL)] (L = NCSC6H4 or H) were explored with terminal alkynes that yielded boratabutadiene complexes [Mn(CO)3{(NCSC6H4)2N}{(R1MeC)=B(HC=CHR1)}] [R1 = phenyl (4a) or p-tolyl (4b)] via triple hydroboration of alkynes. These complexes feature a boratabutadiene ligand that is coordinated to a metal through the η4-CBCC mode. To the best of our knowledge, these are the first examples of η4-E-boratabutadiene-coordinated manganese complexes generated by the trans-hydroboration of alkynes. The steric and electronic effects of the borate ligands have been demonstrated using a less sterically hindered manganese-bis(σ)borate complex, [Mn(CO)3(μ-H)2BH(HN2CSC6H4)], that generated monohydroborated complexes [(CO)3Mn(μ-H)2(HN2CSC6H4)B(R1C=CHR2)] (for 6, R1 = Ph and R2 = H; for 7, R1 = p-Tol and R2 = H; for 8, R1 = R2 = Ph). Theoretical studies using density functional theory methods and chemical bonding analyses established the bonding and stability of these species. © 2019 American Chemical Society.

Sundargopal Ghosh

Department Of Chemistry

Suman Gomosta

Koushik Saha

Urminder Kaur

Kriti Pathak

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Inorganic Chemistry

The field of diborinane is sparsely explored area, and not many compounds are structurally characterized. The room-temperature reaction of [{Cp∗RuCl(μ-Cl)} 2 ] (Cp∗ = η 5 -C 5 Me 5 ) with Na[BH 3 (SCHS)] yielded ruthenium dithioformato [{Cp∗Ru(μ,η 3 -SCHS)} 2 ], 1, and 1-thioformyl-2,6-tetrahydro-1,3,5-trithia-2,6-diborinane complex, [(Cp∗Ru){(η 2 -SCHS)CH 2 S 2 (BH 2 ) 2 }], 2. To investigate the reaction pathway for the formation of 2, we carried out the reaction of [(BH 2 ) 4 (CH 2 S 2 ) 2 ], 3, with 1 that yielded compound 2. To the best of our knowledge, it appears that compound 2 is the first example of a ruthenium diborinane complex where the central six-membered ring [CB 2 S 3 ] adopts the chair conformation. Furthermore, room temperature reaction of 1 with [BH 3 ·thf] resulted in the isolation of agostic-bis(σ-borate) complex, [Cp∗Ru(μ-H) 2 BH(S-CH=S)], 4. Thermolysis of 4 with trace amount of tellurium powder led to formation of bis(bridging-boryl) complex, [{Cp∗Ru(μ,η 2 -HBS 2 CH 2 )} 2 ], 5, via dimerization of 4 followed by dehydrogenation. Compound 5 can be considered as a bis(bridging-boryl) species, in which the boryl units are connected to two ruthenium atoms. Theoretical studies and chemical bonding analyses demonstrate the reason for exceptional reactivity and stability of these complexes. © 2019 American Chemical Society.

Trithia-diborinane and Bis(bridging-boryl) Complexes of Ruthenium Derived from a [BH 3 (SCHS)] ? Ion

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[(H3B)bbza]), trihydro(2-aminobenzothiazolyl)borate (Na[(H3B)abz]), and dihydrobis(2-mercaptopyridyl)borate (Na[(H2B)mp2]) (bbza=bis(benzothiazol-2-yl)amine, abz=2-aminobenzothiazolyl, and mp=2-mercaptopyridyl). Photolysis of [Mn2(CO)10] with Na[(H3B)bbza] formed bis(σ)borate complex [Mn(CO)3(μ-H)2BHNCSC6H4(NR)] (1; R=NCSC6H4). Octahedral complex [Re(CO)2(N3C2S2C12H8)2] (2) was generated under similar reaction conditions with [Re2(CO)10]. Similarly, when [Mn2(CO)10] was treated with Na[(H3B)abz], bis(σ)borate complex [Mn(CO)3(μ-H)2BH(HN2CSC6H4)] (3) and the agostic complex [Mn(CO)3(μ-H)BH(HN2CSC6H4)2] (4) were formed. To probe the potential formation of agostic complexes of the heavier group 7 metals, we carried out the photolysis of [M2(CO)10] with Na[(H2B)mp2] and found that [M(CO)3(μ-H)BH(C5H4NS)2] (5: M=Re; 6: M=Mn) was formed in moderate yield. Complexes 1 and 3 feature a (κ3-H,H,N) coordination mode, whereas 4, 5, and 6 display both (κ3-H,N,N) and (κ3-H,S,S) modes of the corresponding ligands. To investigate the lability of the CO ligands of 1 and 3, we treated the complexes with phosphine ligands that generated novel bis(σ)borate complexes [Mn(μ-H)2(BHNCSC6H4)(NR)(CO)2PL2L’] (R=NCSC6H4; 7 a: L=L’=Ph; 7 b: L=Ph, L’=Me) and [Mn(μ-H)2BHN(NCSC6H4)R(CO)2PL2L’] (R=NCSC6H4; 8 a: L=L’=Ph; 8 b: L=Ph, L’=Me). Complexes 7 and 8 are structural isomers with different coordination modes of the bbza ligand. In addition, DFT calculations were performed to shed some light on the bonding and electronic structures of these complexes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chemistry - A European Journal

Design, Synthesis, and Chemistry of Bis(σ)borate and Agostic Complexes of Group 7 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)Clx]2 as precursors (L′=η6-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*=η5-C5Me5). For example, treatment of Na[(H3B)bbza] or Na[(H2B)mp2] (bbza=bis(benzothiazol-2-yl)amine; mp=2-mercaptopyridyl) with [L′M(μ-Cl)Clx]2 yielded [(η6-p-cymene)RuBH{(NCSC6H4)(NR)}2] (2; R=NCSC6H4), [{N(NCSC6H4)2}RhBH{(NCSC6H4)(NR)}2] (3; R=NCS-C6H4), [(η6-p-cymene)RuBH(L)2] (5; L=C5H4NS), and [Cp*MBH(L)2] (6 and 7; L=C5H4NS, M=Ir or Rh). In order to delineate the significance of the ligands, we studied the reactivity of [(COD)Rh(μ-Cl)]2 with Na[(H3B)bbza], which led to the formation of the isomeric agostic complexes [(η4-COD)Rh(μ-H)BHRh(C14H8N3S2)3], 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. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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

Thermolysis of [CpF∗Ru(PPh2(CH2)PPh2)BH2(L2)] 1 (Cp∗=η5-C5Me5; L=C7H4NS2), with terminal alkynes led to the formation of η4-σ,π-borataallyl complexes [Cp∗Ru(μ-H)B{R-C=CH2}(L)2] (2 a-c) and η2-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-C6H4; L=C7H4NS2) through hydroboration reaction. Ruthenium and the HBCC unit of the vinylborane moiety in 2 a-c are linked by a unique η4-interaction. Conversions of 1 into 3 a-c proceed through the formation of intermediates 2 a-c. Furthermore, in an attempt to expand the library of these novel complexes, chemistry of σ-borane complex [Cp∗RuCO(μ-H)BH2L] 4 (L=C7H4NS2) was investigated with both internal and terminal alkynes. Interestingly, under photolytic conditions, 4 reacts with methyl propiolate to generate the η4-σ,π-borataallyl complexes [Cp∗Ru(μ-H)BH{R-C=CH2}(L)] 5 and [Cp∗Ru(μ-H)BH{HC=CH-R}(L)] 6 (R=COOCH3; L=C7H4NS2) by Markovnikov and anti-Markovnikov hydroboration. In an extension, photolysis of 4 in the presence of dimethyl acetylenedicarboxylate yielded η4-σ,π-borataallyl complex [Cp∗Ru(μ-H)BH{R-C=CH-R}(L)] 7 (R=COOCH3; L=C7H4NS2). An agostic interaction was also found to be present in 2 a-c and 5-7, which is rare among the borataallyl complexes. All the new compounds have been characterized in solution by IR, 1H, 11B, 13C NMR spectroscopy, mass spectrometry and the structural types were unequivocally established by crystallographic analysis of 2 b, 3 a-c and 5-7. DFT calculations were performed to evaluate possible bonding and electronic structures of the new compounds. Building bridges: Hydroboration of σ-borane complexes with alkynes form novel η4-σ,π-borataallyl complexes (see figure). An agostic interaction was also found to be present, which is rare among the borataallyl complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Journal	Data powered by TypesetInorganic Chemistry
Publisher	Data powered by TypesetAmerican Chemical Society
ISSN	00201669
Open Access	No