Room-temperature single-crystal X-ray studies are recorded for a number of
‘acid salts’ formed between Group 1 salts of 4-nitrophenol,
M(4-np), and the parent ligand 4-npH, variously hydrated. The 1 : 1 salts
M(4-np)(4-npH).x H2O are found for
all of M = Li, Na, K, Rb and Cs. The lithium adduct (tetrahydrate) is
monoclinic, C2/c,
a 19·438(4), b
11·207(2), c 7·421(2) Å, β
91·38(2)°, Z = 4, conventional
R on |F| being
0·043 for 1369 independent ‘observed’
(I > 3σ(I))
diffractometer reflections. The sodium adduct (dihydrate) is monoclinic,
C2, a 2·174(3),
b 3·674(2), c
10·358(1) Å, β 117·21(1)°, Z
= 2, R 0·035 for
No 1092; the potassium adduct
(monohydrate) is monoclinic, C
2/c, a 22·10(1),
b 3·798(3), c
21·270(6) Å, β 120·97(4)°, Z
= 4, R 0·050 for
No 1065. The isomorphous rubidium
and caesium monohydrates are triclinic,
P-1, a ≈
11·9, b ≈ 10·2,c
≈ 6·3 Å, α ≈ 90, β ≈ 92, γ ≈ 112°,
Z = 2, R 0·042,
0·028 for No 2340, 3053
respectively. For M = Rb, a 1 : 3 adduct Rb(4-np).3(4-npH) is also
obtained (with an isomorphous thallium counterpart recorded elsewhere):
a 12·143(5), b
11·50(1), c 11·36(1) Å, α
114·38(9), β 110·54(6), γ 96·73(6)°,
Z = 2, R 0·034 for
No 3945. The lithium salt may be
represented as
[Li(OH2)4]+
(4-npH.4-np)½-. The cation lies disposed about a
crystallographic 2 axis; the anion, close to an axis,
confronts its rotational image, with the associated hydrogen atom modelled as
disordered between them, rather than located on the 2
axis. The sodium salt is a sheet structure, the six-coordinate sodium atoms
being disposed on a crystallographic 2 axis and linked
up that axis ...
Na(µ-O)2Na(µ-O)2Na ...
by bridging water molecule oxygen atoms, while symmetry-related trans
O-nitrophenoxide moieties are bridged by confronting
phenoxide oxygen atoms about an associated hydrogen atom provisionally
disposed on a 2 axis also. The potassium salt structure
is developed from this array, modelled with disordered potassium atoms, now
lying off the 2 axis, 0·922(2) Å apart. In
the rubidium/caesium structure, columns of oxygen-bridged metal ions are
disposed about c, crosslinked by
O-nitro-bonded phenoxide moieties, with confronting
phenoxide oxygen atoms about a shared associated hydrogen.