Reaction of PhP(CH2CH2SH)(2) with 1,2-dichloroethane and Cs2CO3 under high
dilution conditions affords 1-phenyl-1-phospha-4,7-dithiacyclononane (L) as
an oil in 52% yield. The geometry of L has been probed by H-1 NMR spectros
copy, which indicates an equilibrium mixture containing gauche S-C-C-S and
S-C-C-P segments, and molecular mechanics calculations which find a lowest
energy endodentate conformation minimum and also energetically accessible e
xodentate minima. Endo- and exodentate conformations are observed in the cr
ystal structure of [Cu(eta(1)-L)(eta(3)-L)][PF6] (1) formed by the reaction
of L with [Cu(NCMe)(4)[PF6]. Reaction of Hg(ClO4)(2) with L affords [HgL2]
[ClO4](2) (2) whose structure has also been established by X-ray diffractio
n. The mercury ion is in a very distorted octahedral environment with two s
hort Hg-P bonds (average 2.404 Angstrom) and four long Hg-S bonds (average
3.092 Angstrom). Reaction of L with AgBF4 or Ni(BF4)(2) or CoBr2 or Fe(BF4)
(2) affords [AgL2][BF4] (3), [NiL2][BF4](2), (4), [CoL2]BL2 (5) and FeL2][B
F4](2) (6), respectively, which were characterised by FAB mass spectroscopy
and elemental analysis. Cyclic voltammetry studies were used to compare th
e redox properties of 4, 5 and 6 with their trithiacyclononane (9S3) analog
ues and in compound 4 the ligand L was found to stabilise Ni in the oxidati
on states 0, I, Il and III. UV-Vis spectroscopic measurements show that L i
s a stronger field ligand than 9S3. EXAFS studies were also performed on 4,
5 and 6, which established that all three complexes are six-coordinate. (C
) 1999 Elsevier Science S.A. All rights reserved.