5 research outputs found
Synthesis and Structure of Distanna and Tristanna Ansa Half-Sandwich Complexes of Ruthenium and Nickel
The synthesis and structural characterization of the
first tin-bridged
ansa half-sandwich complexes via a two-step protocol from NaÂ[η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>RuÂ(CO)<sub>2</sub>] and in situ
generated NaÂ[η<sup>5</sup>-C<sub>5</sub>H<sub>5</sub>NiÂ(CO)]
are presented. Both compounds are characterized by multinuclear NMR
spectroscopy and single-crystal diffraction
Strained <i>ansa</i> Half-Sandwich Complexes of Ruthenium and Osmium and a Non-Iron Metallopolymer by Ring-Opening Polymerization
Herein
we report the first non-iron polymer obtained from an <i>ansa</i> half-sandwich complex. This polymeric organometallic
material was obtained from a new disilanediyl-bridged ruthenium complex
upon thermally induced ring-opening polymerization (ROP). Additionally,
a corresponding distannanediyl-bridged osmium species is reported,
the first example of an <i>ansa</i> half-sandwich complex
of this element
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Strongly phosphorescent transition metal p complexes of boron-boron triple bonds
Herein are reported the first p complexes of compounds with boron-boron triple bonds to transition metals, in this case CuI. Three different compounds were isolated that differ in the number of copper atoms bound to the BB unit. Metallation of the B-B triple bonds causes significant lengthening of the B-B and B-CNHC bonds, as well as large upfield shifts of the 11B NMR signals, suggesting greater orbital interactions between the boron and transition metal atoms than those observed with recently published diboryne / alkali metal cation complexes. In contrast to previously-reported fluorescent copper(I) p complexes of boron-boron double bonds, the Cun-p-diboryne compounds (n = 2, 3) show intense phosphorescence in the red to near-IR region from their triplet excited states, according to their microsecond lifetimes, with quantum yields of up to 58%. The bonding situation, as well as the unusual photophysical properties, has been further corroborated by DFT studies
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Exclusive p encapsulation of light alkali metal cations by a neutral molecule
Cation-p interactions are one of the most important classes of non-covalent bonding, and are seen throughout biology, chemistry and materials science. However, in almost every documented case, these interactions play only a supporting role to much stronger covalent or dative bonds, making examples of exclusive cation-p bonding exceedingly rare. In this work, a neutral diboryne molecule is found to encapsulate the light alkali metal cations Li+ and Na+ in the absence of a net charge, covalent bonds, or lone-pair donor groups. The resulting encapsulation complexes are to our knowledge the first structurally authenticated species in which a neutral molecule binds the light alkali metals exclusively through cation-p interactions
Experimental Assessment of the Strengths of B–B Triple Bonds
Diborynes, molecules
containing homoÂatomic boron–boron
triple bonds, have been investigated by Raman spectroscopy in order
to determine the stretching frequencies of their central Bî—¼B
units as an experimental measure of homoatomic bond strengths. The
observed frequencies between 1600 and 1750 cm<sup>–1</sup> were
assigned on the basis of DFT modeling and the characteristic pattern
produced by the isotopic distribution of boron. This frequency completes
the series of known stretches of homoatomic triple bonds, fitting
into the trend established by the long-known stretching frequencies
of Cî—¼C and Nî—¼N triple bonds in alkynes and dinitrogen,
respectively. A quantitative analysis was carried out using the concept
of relaxed force constants. The results support the classification
of the diboryne as a true triple bond and speak to the similarities
of molecules constructed from first-row elements of the p block. Also
reported are the relaxed force constants of a recently reported diborabutatriene,
which again fit into the trend established by the vibrational spectroscopy
of organic cumulenes. As part of these studies, a new diboryne with
decreased steric bulk was synthesized, and a computational study of
the rotation of the stabilizing ligands indicated alkyne-like electronic
isolation of the central B<sub>2</sub> unit