The plastic crystalline A15 phase of dimethylaminoalane, [N(CH3)2-AlH2]3

A plastic crystalline phase of dimethylaminoalane has been discovered at T > 332 K. The phase transitions solid - plastic phase - liquid are fully reversible. The plastic crystalline phase exhibits a cubic unit cell, space group Pm3[combining macron]n, in which the dimethylaminoalane molecules rotate and adopt a structural arrangement reminiscent of the A15 phase.

The influence of LiH on the rehydrogenation behavior of halide free rare earth (RE) borohydrides (RE = Pr, Er)

Rare earth (RE) metal borohydrides are receiving immense consideration as possible hydrogen storage materials and solid-state Li-ion conductors. In this study, halide free Er(BH4)3 and Pr(BH4)3 have been successfully synthesized for the first time by the combination of mechanochemical milling and/or wet chemistry. Rietveld refinement of Er(BH4)3 confirmed the formation of two different Er(BH4)3 polymorphs: α-Er(BH4)3 with space group Pa3[combining macron], a = 10.76796(5) Å, and β-Er(BH4)3 in Pm3[combining macron]m with a = 5.4664(1) Å. A variety of Pr(BH4)3 phases were found after extraction with diethyl ether: α-Pr(BH4)3 in Pa3[combining macron] with a = 11.2465(1) Å, β-Pr(BH4)3 in Pm3[combining macron]m with a = 5.716(2) Å and LiPr(BH4)3Cl in I4[combining macron]3m, a = 11.5468(3) Å. Almost phase pure α-Pr(BH4)3 in Pa3[combining macron] with a = 11.2473(2) Å was also synthesized. The thermal decomposition of Er(BH4)3 and Pr(BH4)3 proceeded without the formation of crystalline products. Rehydrogenation, as such, was not successful. However, addition of LiH promoted the rehydrogenation of RE hydride phases and LiBH4 from the decomposed RE(BH4)3 samples.

Molecular structure of diethylaminoalane in the solid state: an X-ray powder diffraction, DFT calculation and Raman spectroscopy study

The crystal structure of diethylaminoalane, [H2Al-N(C2H5)2]2, was determined by X-ray powder diffraction in conjunction with DFT calculations. Diethylaminoalane crystallizes in the monoclinic space group P21/c with a = 7.4020 (2), b = 12.9663 (3), c = 7.2878 (2) Å and β = 90.660 (2)° at 293 K. The crystal structure was confirmed by DFT calculations and Raman spectroscopy. The molecular structure of diethylaminoalane consists of dimers of [H2Al-N(CH2CH3)2] in which an Al2N2 four-membered ring is formed by a center of inversion. Such an arrangement of the aminoalane moieties in the crystal structure is well known for this class of compound, as shown by the comparison with ethylmethylaminoalane and diisopropylaminoalane.

Synthesis and thermal stability of perovskite alkali metal strontium borohydrides

Synthesis of new thermally stable perovskite-type metal strontium borohydrides, MSr(BH₄)₃ (M = K, Rb, Cs).

Synthesis, structure and properties of new bimetallic sodium and potassium lanthanum borohydrides

New compounds, NaLa(BH₄)₄ and K₃La(BH₄)₆, are synthesized. NaLa(BH₄)₄ has a new structure type and has partial reversibility for hydrogen release.

Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM) fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability.

Novel solvates M(BH₄)₃S(CH₃)₂ and properties of halide-free M(BH₄)₃ (M = Y or Gd)

Rare earth metal borohydrides have been proposed as materials for solid-state hydrogen storage because of their reasonably low temperature of decomposition. New synthesis methods, which provide halide-free yttrium and gadolinium borohydride, are presented using dimethyl sulfide and new solvates as intermediates. The solvates M(BH4)3S(CH3)2 (M = Y or Gd) are transformed to α-Y(BH4)3 or Gd(BH4)3 at ~140 °C as verified by thermal analysis. The monoclinic structure of Y(BH4)3S(CH3)2, space group P2₁/c, a = 5.52621(8), b = 22.3255(3), c = 8.0626(1) Å and β = 100.408(1)°, is solved from synchrotron radiation powder X-ray diffraction data and consists of buckled layers of slightly distorted octahedrons of yttrium atoms coordinated to five borohydride groups and one dimethyl sulfide group. Significant hydrogen loss is observed from Y(BH4)3 below 300 °C and rehydrogenation at 300 °C and p(H2) = 1550 bar does not result in the reformation of Y(BH4)3, but instead yields YH3. Moreover, composites systems Y(BH4)3-LiBH4 1 : 1 and Y(BH4)3-LiCl 1 : 1 prepared from as-synthesised Y(BH4)3 are shown to melt at 190 and 220 °C, respectively.

Tailoring the properties of ammine metal borohydrides for solid-state hydrogen storage

A series of halide-free ammine manganese borohydrides, Mn(BH4 )2 ⋅nNH3 , n=1, 2, 3, and 6, a new bimetallic compound Li2 Mn(BH4 )4 ⋅6NH3 , and the first ammine metal borohydride solid solution Mg1-x Mnx (BH4 )2 ⋅6NH3 are presented. Four new crystal structures have been determined by synchrotron radiation powder X-ray diffraction and the thermal decomposition is systematically investigated for all the new compounds. The solid-gas reaction between Mn(BH4 )2 and NH3 provides Mn(BH4 )2 ⋅6NH3 . The number of NH3 per Mn has been varied by mechanochemical treatment of Mn(BH4 )2 ⋅6NH3 -Mn(BH4 )2 mixtures giving rise to increased hydrogen purity for n/m≤1 for M(BH4 )m ⋅nNH3 . The structures of Mg(BH4 )2 ⋅3NH3 and Li2 Mg(BH4 )4 ⋅6NH3 have been revisited and new structural models are presented. Finally, we demonstrate that ammonia destabilizes metal borohydrides with low electronegativity of the metal (χp <∼1.6), while metal borohydrides with high electronegativity (χp >∼1.6) are generally stabilized.

Borohydrides: from sheet to framework topologies

The five novel compounds ALiM(BH4)4 (A = K or Rb; M = Mg or Mn) and K3Li2Mg2(BH4)9 crystallizing in the space groups Aba2 and P2/c, respectively, represent the first two-dimensional topologies amongst homoleptic borohydrides. The crystal structures have been solved, refined and characterized by synchrotron X-ray powder diffraction, neutron powder diffraction and solid-state DFT calculations. Minimal energies of ordered models corroborate crystal symmetries retrieved from diffraction data. The layered Li-Mg substructure forms negatively charged uninodal 4-connected networks. It is shown that this connectivity cannot generate the long sought-after, bimetallic Li-Mg borohydrides without countercations when assuming preferred coordination polyhedra as found in Mg(BH4)2 and LiBH4. The general properties of the trimetallic compound series are analogous with the anhydrous aluminosilicates. Additionally, a relationship with zeolites is suggested, which are built from three-dimensional Al-Si-O networks with a negative charge on them. The ternary metal borohydride systems are of interest due to their potential as novel hydridic frameworks and will allow exploration of the structural chemistry of light-metal systems otherwise subject to eutectic melting.

Eutectic melting of LiBH4–KBH4

Extremely low eutectic melting temperature and pressure stabilisation of a bi-metallic borohydride with implication for mechanochemistry.

Abstract P1-12-03: Primary squamous cell carcinoma of the breast

BACKGROUND: Primary squamous cell carcinoma of the breast (PSCCB) is one of the rarest forms of breast cancer, accounting for less than 0.1% of all breast cancers. PSCCB can be aggressive with no typical radiologic findings on mammogram, often leading to delays in diagnoses or missed diagnoses. Previously reported cases of PSCCB have illustrated a wide range of clinical presentations, from an abnormal mammogram with no obvious breast mass to a breast abscess. In addition, due to the rarity of this disease, no clear consensus on definitive treatment or prognosis exists.

METHODS: Using a search of our pathology database, we identified females diagnosed with PSCCB at our institution from 2007-2012. Inclusion criteria included female patients over the age of 18 years old with a primary tumor consisting of &gt;90% malignant cells of squamous origin. Likewise, exclusion criteria included squamous cell cancer that had metastasized to the breast from elsewhere or lesions that were not independent of the overlying skin or nipple. We then performed a retrospective review to evaluate patient characteristics, presentation, tumor characteristics, treatment modalities and outcomes.

RESULTS: We identified three patients who were diagnosed with PSCCB during that timeframe. Their ages ranged from 35-65 years old, with two being post-menopausal and one pre-menopausal. Of the three, two were Caucasian and one was Hispanic. All three presented after self-palpating a breast mass. The average size of the mass seen on mammogram was 2.9 cm (range of 2.4 to 3.6 cm). Histologically, all three of the cancers were moderately to poorly differentiated. In addition, they all had a negative estrogen, progesterone, and HER2 receptor status with an elevated Ki-67. One patient was diagnosed at our institution but did not proceed to surgery and was lost to follow up. For the other two patients, one chose to undergo breast conservation with partial mastectomy and sentinel lymph node biopsy followed by whole breast radiation. The second patient proceeded with a total mastectomy and sentinel lymph node biopsy without radiation. There was no evidence of regional nodal disease in either patient at time of surgery. Furthermore, neither patient received any systemic therapy. Both patients were disease free at last follow up which was 5 and 11 months respectively.

CONCLUSION: Because PSCCB is so rare, prognosis and optimal treatment are still controversial. Most of the current literature portrays PSCCB as an aggressive cancer with a poor prognosis. This often leads to multimodality therapy consisting of mastectomy with axillary nodal clearance, adjuvant chemotherapy and radiation. In addition, locoregional and distant recurrences are common despite this aggressive treatment leading to the conclusion that PSCCB is relatively radioresistant with limited activity seen when using conventional breast cancer systemic therapies. Because treatment options can be limited, more research is needed to further elucidate the biological behavior of this rare cancer as well prognostic factors that may allow us to treat a patient more conservatively.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-12-03.