Figure 2
A simplified packing diagram for (I), showing the Ca coordination sphere (thin solid lines) and zwitterionic hydrogen bonds (dotted lines), as well as some involving N atoms and water (dashed lines). Atoms labelled with a dollar sign ($), ampersand (&), hash (#), prime (′), tilde (~) or asterisk (*) are at symmetry positions (1 − x, −y, −z), (1 − x, y, −z − ), (1 − x, 1 − y, −z), (x + , − y, z + ), ( − x, − y, −z) or (x + , y + , z), respectively. |