The structures of
Au(4-C≡CC6H4XYC6H4-4′-NO2)(PPh3)
(XY = (E )-CH=CH
(1), (Z)-CH=CH (2), C≡C (3), N=CH
(4)) have been determined by single-crystal X-ray diffraction analyses,
refining by full-matrix least-squares analysis. For (1), crystals are
triclinic, space group P-1, with
a8·847(1), b
17·870(4), c 19·705(3) Å,
α116·25(1), β 93·33(1), γ 92·64(2)˚,
Z 4, 6747 unique reflections (703 parameters),
converging at R 0·025 and
Rw 0·029. For (2), crystals
are monoclinic, space group P
21/a, with
a 10·718(6), b
19·398(5), c14·469(3) Å, β
108·96(2)˚, Z 4, 3295 unique reflections
(352 parameters), converging atR 0·040 and
Rw 0·034. For (3), crystals
are triclinic, space group P-1,
with a 10·671(4), b
17·599(7), c 18·220(8) Å, α
116·31(3), β 105·00(4), γ 95·08(4)˚,
Z 4, 4828 unique reflections (703 parameters),
converging at R 0·043 and
Rw 0·030. For (4), crystals
are triclinic, space group P-1,
with a 8·8314(6), b
17·834(2), c 20·001(2) Å, α
115·249(7), β 90·930(7), γ 94·082(7)˚,
Z 4, 4724 unique reflections (703 parameters),
converging at R 0·035 and
Rw 0·034. Despite the
[ligated metal donor]-bridge-[nitro acceptor] composition
of these complexes, Au–C and C≡C distances are normal and
consistent with minimal allenylidene contribution to the ground-state
geometry. Within the 3σ confidence limits, the structural data do not
provide evidence for π*-back-bonding in these complexes
Ground state geometry of binary condensates in axisymmetric traps
