Binary salt of a palladium(II) complex with (phosphonomethyl)phosphonic (medronic) acid comprising `handbell-like' [Pd{μ-CH2(PO3)2}]3units

The asymmetric unit of the title compound, dipotassium bis[hexaaquanickel(II)] tris(μ2-methylenediphosphonato)tripalladium(II) hexahydrate, K2[Ni(H2O)6]2[Pd3{CH2(PO3)2}3]·6H2O, consists of half a {[Pd{CH2(PO3)2}]3}6−anion [one Pd atom (4e) and a methylene C atom (4e) occupy positions on a twofold axis] in a rare `handbell-like' arrangement, with K+and [Ni(H2O)6]2+cations to form the neutral complex, completed by three solvent water molecules. The {[Pd{CH2(PO3)2}]3}6−units exhibit close Pd...Pd separations of 3.0469 (4) Å and are packedviaintermolecular C—H...Pd hydrogen bonds. The [KO9] and [NiO6] units are assembled into sheets coplanar with (011) and stacked along the [100] direction. Within these sheets there are [K4Ni4O8] and [K2Ni2O4] loops. Successive alternation of the sheets and [Pd{CH2(PO3)2}]3units parallel to [001] produces the three-dimensional packing, which is also supported by a dense network of hydrogen bonds involving the solvent water molecules.

Temporal correlations in sensory-synaptic interactions: example in crayfish stretch receptors

1. The effects of inhibitory postsynaptic potential (IPSP) barrages on coding of sinusoidal length inputs were investigated in slowly and rapidly adapting stretch receptors of crayfish (RM1 and RM2, respectively). To examine the contribution of postsynaptic firings, a description was obtained of the temporal correlations between sensory stimuli, pre- and postsynaptic spikes, plus the relative position of the latter. In this analysis, the times between an IPSP and the closest spike preceding or following it are known, respectively, as phase (phi) and cophase (theta). 2. Interactions were similar in RM1 and RM2. The usual effect was the expected increased postsynaptic interval durations, but special consequences were also evoked. With regular IPSPs there were epochs including inhibitory (S) and postsynaptic (R) spikes and fixed "alternations" at S/R times the IPSP rate. S/R ratios were usually 1:1 and 1:2, more rarely 2:1. There were sudden postsynaptic interval duration changes, or "jumps," between successive alternation ratios where inhibitory effects increased or decreased. With 1:1 and 1:2 ratios there was a gradual "sliding," or phi increase-theta decrease, at the pull and the opposite at the release. The theta and phi roughly paralleled the control postsynaptic intervals and the inhibited-minus-control differences, respectively, when sliding was present. Sliding disappeared, and phi and theta tended to become invariant, with 2:1 ratio. 3. Irregular IPSP increased postsynaptic interval irregularities and eliminated alternations. Phase values were irregularly distributed, but theta and control postsynaptic intervals were similar irrespective of pattern.(ABSTRACT TRUNCATED AT 250 WORDS)