The synthesis and structural characterization of bis(mercaptoimidazolyl)hydroborato complexes of lithium, thallium and zinc †

Synthesis and structure of an acyclic dialkylstannylene

“…The lithium ion is bound by the carbanion centre and one of the hydrogen atoms of the BH 3 group to give a pseudo-four-membered chelate ring, and the coordination of Li is completed by two nitrogen atoms from a molecule of TMEDA, affording a pseudo-tetrahedral geometry about the lithium ion. The Li-C(1) distance [2.213(3) Å] is similar to the corresponding distances in previously reported lithium complexes of phosphine-borane-stabilised carbanions (Izod et al, 2004(Izod et al, , 2006c(Izod et al, , 2007(Izod et al, , 2010(Izod et al, , 2014, while the Li…H(1B) distance [2.02(2) Å] lies in the normal range for η 1 -BH n …Li contacts (Kimblin et al, 2000;Franz et al, 2011), although we note that such contacts are rare in comparison with η 2 -and η 3 -BH n …Li interactions. The carbanion centre adopts a pyramidal geometry (sum of angles in the CHSiP framework = 350.7°).…”

Thiolate exchange in [TmR]ZnSR′ complexes and relevance to the mechanisms of thiolate alkylation reactions involving zinc enzymes and proteins

“…2. Results and discussion Although the active site of the Ada DNA repair protein exhibits a [Cys 4 Zn] motif, structurally characterized examples of mononuclear complexes with tetrahedral [S 4 Zn] motifs are not well precedented, with the majority of examples being arylthiolate derivatives, such as [Zn(SAr) 4 ] 2À [53-59], [Tm R ]ZnSPh [44,45] and [PhB(CH 2 SBu t ) 3 ]ZnSPh [30]; other structurally characterized mononuclear complexes with the [S 4 Zn II ] coordination geometry are also known[60][61][62][63][64][65][66][67][68]. For this reason, we sought to obtain improved structural models for the active site of Ada by synthesizing complexes in which the thiolate more closely resembles a cysteine thiolate than does an arylthiolate.…”

HMB and Cp* ruthenium(II) complexes containing bis- and tris-(mercaptomethimazolyl)borate ligands: Synthetic, X-ray structural and electrochemical studies (HMB=η6-C6Me6, Cp*=η5-C5Me5)

“…As in the reaction of [Cp*RuOMe] 2 with KTm to yield Cp*Ru II (Tm) C [15], it was found that [Cp*RuOMe] 2 was a good precursor to Cp*Ru II (Bm) (3), which was obtained as orange crystals in 85% yield from a 2 h reaction with NaBm at room temperature (Scheme 5). …”

“…Its coordination chemistry and that of the allied ligand H 2 B(mt R ) 2 (also abbreviated as Bm R ) [3] has been rapidly developing in several laboratories; to date complexes of types M(Tm) [4], M(Tm) 2 and M(Bm) 2 [4f,5] and [M(Tm)X] [X = Cl, Br, I] [5d,6] of first row transition metals of Groups 8-10, of Groups 11 and 12 metals and of the main group elements Tl, Sn, Pb, As and Bi, have been prepared.…”