New crystalline coordination networks based on Ag(i) and N-bridging ligands -pyrazine (pyz), 4,4bipyridine (bpy), and 2,3-bis-(2-pyridyl)pyrazine (bppz) -incorporating carborane monoanions (CB 11 H 12 ) − or [Co(C 2 B 9 H 11 ) 2 ] − were isolated and characterized using single crystal X-ray diffraction, microanalysis, and infrared spectroscopy. All the complexes with the bpy and bppz ligands reveal 1D coordination infinite chains involving the Ag(i) and the ligands, and layered extended structures with rows of carborane anions between the layers of chains. Interestingly, two polymorphs of the complex [Ag(bpy)(CH 3 CN)][Co(C 2 B 9 H 11 ) 2 ] were observed. The complex [Ag(pyz)(CH 3 CN) 2 ][Co(C 2 B 9 H 11 ) 2 ] shows a 1D coordination polymer, while the pyz complex with the smaller carborane anion {[Ag(pyz)](CB 11 H 12 )} exhibits a 3D coordination network structure with four Ag· · ·H-B interactions between the silver centre and carborane anions.

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The crystal structure of the silver complex Ag(CH3CN)2[Co(C2B9H11)2] has been determined and features trigonal bipyramidal Ag(I) with B−H···Ag interactions comprising the trigonal plane. When the host molecule cyclotriveratrylene (CTV) is combined with silver(I) cobalt(III) bis(dicarbollide), different supramolecular assemblies with various Ag(I) coordination environments result, depending on the crystallization conditions used. The complex Ag(CH3CN)(H2O)(CTV)2[Co(C2B9H11)2] has tetrahedral Ag(I) with coordination interactions with water, acetonitrile, and CTV through Ag−C bonds, and the structure features bis(CTV) capsules. The complexes Ag(CH3CN)3(CTV)[Co(C2B9H11)2](CH3CN)0.5 and Ag(CH3CN)4(CTV)[Co(C2B9H11)2](CH3CN)0.25 both have [Ag(CH3CN) n ]+ complex cations forming host−guest interactions with the CTV. In the former case, three CH3CN ligands bind to Ag(I) and there are further weak Ag−O coordinate interactions to the CTV, whereas the latter features the more usual tetrahedral [Ag(CH3CN)4]+. Complexes with CTV show host−guest interactions with coordinated acetonitrile guests.

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Undercooling experiments have been performed on an Ni-25.2 at.% Si alloy using a flux encasement technique, with a maximum undercooling of 160 K having been achieved. Double recalescence was observed at all undercoolings, with crystal growth velocities being measured for the first recalescence event. These velocities were extremely low, with a maximum value of 0.018 m s -1 being recorded. At all undercoolings a eutectic structure was observed, comprising alternating lamellae of single phase γ(Ni 31 Si 12 ) and Ni-rich lamellae containing of a fine (200-400 nm) dispersion of βNi 3 Si and αNi. This is contrary to the equilibrium phase diagram from which direct solidification to βNi 3 Si would be expected for undercoolings in excess of 53 K. We postulate that the direct solidification of βNi 3 Si from the melt is suppressed, with an α-γ eutectic being formed instead. The α appears to be supersaturated in Si and undergoes a eutectoid decomposition to α and βNi 3 Si, giving rise to the observed second recalescence.