Synthesis and characterization of [Ir(1,5-cyclooctadiene)(μ-H)]4: a tetrametallic Ir4H4-core, coordinatively unsaturated cluster

Reported herein is the synthesis of the previously unknown [Ir(1,5-COD)(μ-H)](4) (where 1,5-COD = 1,5-cyclooctadiene), from commercially available [Ir(1,5-COD)Cl](2) and LiBEt(3)H in the presence of excess 1,5-COD in 78% initial, and 55% recrystallized, yield plus its unequivocal characterization via single-crystal X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) spectroscopy, electrospray/atmospheric pressure chemical ionization mass spectrometry (ESI-MS), and UV-vis, IR, and nuclear magnetic resonance (NMR) spectroscopies. The resultant product parallels--but the successful synthesis is different from, vide infra--that of the known and valuable Rh congener precatalyst and synthon, [Rh(1,5-COD)(μ-H)](4). Extensive characterization reveals that a black crystal of [Ir(1,5-COD)(μ-H)](4) is composed of a distorted tetrahedral, D(2d) symmetry Ir(4) core with two long [2.90728(17) and 2.91138(17) ?] and four short Ir-Ir [2.78680 (12)-2.78798(12) ?] bond distances. One 1,5-COD and two edge-bridging hydrides are bound to each Ir atom; the Ir-H-Ir span the shorter Ir-Ir bond distances. XAFS provides excellent agreement with the XRD-obtained Ir(4)-core structure, results which provide both considerable confidence in the XAFS methodology and set the stage for future XAFS in applications employing this Ir(4)H(4) and related tetranuclear clusters. The [Ir(1,5-COD)(μ-H)](4) complex is of interest for at least five reasons, as detailed in the Conclusions section.     

Ti6Al4V foams having nanotubular surfaces for orthopaedic applications

Despite the widespread use of Ti6Al4V in orthopaedics, the bioinert nature of this alloy limits its biological fixation with the bone tissue. To enhance its bone fixation, two different types of Ti6Al4V foams were fabricated, and their surfaces were modified zto possess nanofeatures. To prepare the foams, spherical- or irregular-shaped Ti6Al4V particles were used to form the backbones of the foams, while magnesium or carbamide powders were used as space holder agents. Once Ti6Al4V foams were fabricated, oxide-based nanotubular arrays having 40 nm diameter were formed on the interconnected pore surfaces via anodization. Results showed successful growth of nanotubular oxide arrays independent of the pore surface morphology, chemistry, and porosity content. Nanotubular surfaces induced formation of calcium phosphate minerals independent of the Ti6Al4V particle type and the space holder agent. Thus, anodized nanotubular Ti6Al4V foams could potentially induce enhanced integration of Ti6Al4V-based porous implants with the bone tissue.     

A remark on the paper “Laterally closed lattice homomorphisms”

A new and simple proof of the main result of the paper “Laterally closed lattice homomorphisms” by Toumi and Toumi (J Math Anal Appl 324:1178–1194, 2006) is given following the paper “Extension of Riesz homomorphisms, I” by Buskes (J Aust Math Soc Ser A 39(1):107–120, 1985).     

CD0(K,E) and CDω(K,E)-Spaces as Banach Lattices

Banach lattices CD ₀(K,E) and CD (K,E) are introduced and lattice-norm properties of these spaces are investigated. We identify the centre and order continuous dual of these spaces.     

A remark on the homomorphism on

Let be a real compact space. Without using the axiom of choice we present a simple and direct proof that a non-zero homomorphism on is determined by a point.

     

On a Fitting length conjecture without the coprimeness condition

Let A be a finite nilpotent group acting fixed point freely by automorphisms on the finite solvable group G. It is conjectured that the Fitting length of G is bounded by the number of primes dividing the order of A, counted with multiplicities. The main result of this paper shows that the conjecture is true in the case where A is cyclic of order p ⁿ q, for prime numbers p and q coprime to 6 and G has abelian Sylow 2-subgroups.