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Photolysis of [{(μ3-BH)(Cp*Ru)Fe(CO)3}2(μ-CO)] (1; Cp* = η5-C5Me5) in the presence of various alkynessuch as 1,2-diphenylethyne, 1-phenyl-1-propyne, 2-butyne, and 1-(diphenylphosphino)-2-phenylacetyleneled to the formation of four types of novel heterometallic metallacarboranes,[1,1,1-(CO)3-μ-2,3-(CO)-2,3-(Cp*)2-4,6-Ph2-closo-1,2,3,4,6-FeRu2C2BH] (2), [1,8-(Cp*)2-2,2,7,7-(CO)4-μ-2,8-(CO)-μ-7,8-(CO)-4-Me-5-Ph-pileo-1,2,7,4,5-RuFe2C2(BH)2] (3), [1,8-(Cp*)2-2,2,7,7-(CO)4-μ-2,8-(CO)-μ-7,8-(CO)-4,5-Me2-pileo-1,2,7,4,5-RuFe2C2(BH)2] (4), and [1,2-(Cp*)2-6,6,7,7-(CO)4-μ-2,7-(CO)-exo-μ-5,6-(PPh2)-μ3-1,2,6-(BH)-4-Ph-pileo-1,2,6,7,4,5-Ru2Fe2C2BH] (5). Cluster compound 2exhibits an octahedralstructure with adjacent carbon atoms consistent with its skeletalelectron pair (sep) count of 7. The cage geometry of 3and 4is based on a pentagonal bipyramid with one additional{Cp*Ru} vertex capping one of its faces. The solid-state X-ray diffractionresults of 5suggest that the core geometry is a cappedpentagonal bipyramid, with an Fe–C bridging PPh2group. All the cluster compounds 2–5have been characterized by IR and 1H, 11B,and 13C NMR spectroscopy, and the geometries of the structureswere unequivocally established by crystallographic analysis. [ABSTRACT FROM AUTHOR]

A new class of cyclazine analogues with periphery reminiscent of an aza[10]annulene framework, tethered internally by an sp 3 carbon, is presented. In depth structure analysis based on NMR and X-ray diffraction data gave a deeper insight into the effect of electron delocalization on their structure and properties. A characteristic change in chemical shift positions suggested an aromatic ring current in these systems. Attractive emission properties in solid and solution states involving charge transfer is another highlight.

Synthesis and structural elucidation of various electron precise group 5 dimetallaheteroboranes have been described. Room temperature reaction of [Cp 2 VCl 2 ] with Li[BH 3 (EPh)], generated from the treatment of LiBH 4 ·THF and Ph 2 E 2 (E = S or Se), for 1 h in toluene, followed by thermolysis, led to the formation of bimetallic complexes [{CpV(μ-EPh)} 2 {μ-η 2 :η 2 -BH 3 E}], 1 and 2 (1: E = S and 2: E = Se), and [{CpV(μ-SePh)} 2 {μ-η 2 :η 2 -BH(OC 4 H 8 )Se}], 3. One of the striking features of these compounds is that they represent a rare class of distorted tetrahedral clusters having bridging hydrogens. Evaluating the skeletal electron pairs and bonding types, compounds 1, 2, and 3 may be considered as isoelectronic with our earlier reported [(CpV) 2 (B 2 H 6 ) 2 ]. In an attempt to synthesize the Nb analogues of 1-3, room temperature reactions of [CpNbCl 4 ] and Li[BH 3 (EPh)] (E = S or Se) were carried out that afforded compounds [{CpNb(μ-EPh)} 2 {μ-η 2 :η 2 -B 2 H 4 E}], 4 and 5 (4: E = S and 5: E = Se). The solid-state X-ray structures of both 4 and 5 exemplify electronically saturated [M 2 B 3 ] systems, and their geometries are analogous to that of [(Cp*MoCl) 2 B 3 H 7 ]. For the extension of this work, reaction of [Cp*TaCl 4 ] (Cp* = η 5 -C 5 Me 5 ) with Li[BH 3 (SePh)] was carried out that yielded a tantalaselenaborane cluster [(Cp*Ta) 2 (μ-Se)B 3 H 6 Se(C 6 H 5 )] (6). All the new compounds have been characterized using 1 H, 11 B{ 1 H}, 13 C{ 1 H} NMR, UV-vis absorption, and IR spectroscopy, mass spectrometry, and X-ray diffraction studies.

Two simple biphenyl-appended (2-pyridyl)alkylamine N -bidentate ligands, L e and L m , having ethylene and methylene spacers between donor groups, with bite angles L e ≈ 100° and L m ≈ 80°, dictate pseudotetrahedral and trigonal-bipyramidal geometries in six high-spin Ni(II)-halide complexes, [Ni(L e )X 2 ] and [Ni(L m ) 2 X](ClO 4 ) (where X = Cl - , Br - , I - ), respectively. The structures in the solid state, determined using X-ray crystallography, and in solution, determined using spectroscopic methods (UV-vis-NIR and paramagnetic 1 H NMR), which complement each other, are described., Competing Interests: The authors declare no competing financial interest.

Dinuclear salen compounds of zirconium and hafnium are efficient initiators for the solvent-free ring-opening polymerization of cyclic ester monomers and lactides. There is a correlation between the theoretical and experimental number-average molecular weights (M(n)'s) in these polymerizations. Polymerization of β-butyrolactone gives poly(3-hydroxybutyrate) with a good M(n) and molecular weight distribution.

Pyrolysis of (eta(5)-C(5)Me(5)WH(3))B(4)H(8), 1, in the presence of excess BHCl(2) x SMe(2) in toluene at 100 degrees C led to the isolation of (eta(5)-C(5)Me(5)W)(2)B(5)H(9), 2, and B-Cl inserted (eta(5)-C(5)Me(5)W)(2)B(5)H(8)Cl, 3, and (eta(5)-C(5)Me(5)W)(2)B(5)H(7)Cl(2), 4-7 (four isomers). All the chlorinated tungstaboranes were isolated as red and air and moisture sensitive solids. These new compounds have been characterized in solution by (1)H, (11)B, (13)C NMR, and the structural types were unequivocally established by crystallographic analysis of compounds 3, 4, and 7. Density functional theory (DFT) calculations were carried out on the model molecules of 3-7 to elucidate the actual electronic structures of these chlorinated species. On grounds of DFT calculations we demonstrated the role of transition metals, bridging hydrogens, and the effect of electrophilic substitution of hydrogens at B-H vertices of metallaborane structures.