Structural diversity of cadmium(II) complexes of tetraorganodichalcogenoimidodiphosphinato ligands: Monomeric Cd[(SPMe 2)2N]2, dinuclear [Cd{(OPMe2) (SPPh2)N}2]2 and [Cd2{(OPPh 2)2N}4(H2O)], and trinuclear K[Cd2{(OPPh2)2N}5]

Article abstract of DOI:10.1016/j.ica.2005.04.046

Cadmium complexes of the type Cd[(XPR2)(YPR2′)N]2(X,Y=O,S;R,R′= Me,Ph) were obtained by reacting CdCl₂ and K[(XPR2)(YPR2′)N] in a 1:2 molar ratio. The compounds were characterized by IR, multinuclear NMR (¹H, ¹³C, ³¹P) spectroscopy and mass spectrometry. The molecular structures of Cd[(SPMe₂) ₂N]₂ (1), Cd[(OPMe₂)(SPPh₂)N] ₂ (4), [Cd₂{(OPPh₂)₂N} ₄(H₂O)] (7 ? H₂O) and K[Cd ₂{(OPPh₂)₂N}₅] (8) were established by single-crystal X-ray diffraction. Colourless crystals of 8 were isolated, along with those of 7 ? H₂O, during recrystallization of crude Cd[(OPPh₂)₂N]₂ (7). A monomeric structure with a tetrahedral CdS₄ core is found for 1, whereas 4 contains discrete dimers formed through two O,O′, S-bimetallictriconnective ligand units resulting in distorted trigonal bipyramidal CdO₃S₂ cores. In the dinuclear compound 7 ? H₂O the Cd atoms are also bridged by two O,O′,O′-bimetallic triconnective ligands, but the coordination of the metal centres is completed by a bridging water molecule to givedistorted octahedral CdO₆ cores. In the trimetallic unit of 8 the K atom is accommodated in the cavity described by the oxygen atoms of three ligand units which bridge the Cd atoms. The remaining two ligands are each one chelating a Cd atom, thus resulting in distorted square pyramidal CdO ₅ cores.

Full text of DOI:10.1016/j.ica.2005.04.046

Inorganica Chimica Acta 358 (2005) 3724–3734
www.elsevier.com/locate/ica
Structural diversity of cadmium(II) complexes of
tetraorganodichalcogenoimidodiphosphinato ligands:
Monomeric Cd[(SPMe2)2N]2, dinuclear [Cd{(OPMe2)(SPPh2)N}2]2
and [Cd2{(OPPh2)2N}4(H2O)], and trinuclear K[Cd2{(OPPh2)2N}5]
a
a,
a
b
Mihaela Ghesner , Anca Silvestru *, Cristian Silvestru , John E. Drake ,
c
Michael B. Hursthouse , Mark E. Light
c
a
Facultatea de Chimie si Inginerie Chimica, Universitatea Babes-Bolyai, RO-400028 Cluj-Napoca, Romania
b
Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ont. N9B 3P4, Canada
c
Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, Great Britain
Received 2 March 2005; accepted 6 April 2005
Available online 20 July 2005
Abstract
Cadmium complexes of the type Cd½ðXPR2ÞðYPR02ÞNꢀ ðX; Y ¼ O; S; R; R0 ¼ Me; PhÞ were obtained by reacting CdCl2 and
2
K½ðXPR2ÞðYPR0 ÞNꢀ in a 1:2 molar ratio. The compounds were characterized by IR, multinuclear NMR (1H, 13C, 31P) spectroscopy
2
and mass spectrometry. The molecular structures of Cd[(SPMe2)2N]2 (1), Cd[(OPMe2)(SPPh2)N]2 (4), [Cd2{(OPPh2)2N}4(H2O)]
(7ÆH2O) and K[Cd2{(OPPh2)2N}5] (8) were established by single-crystal X-ray diffraction. Colourless crystals of 8 were isolated,
along with those of 7ÆH2O, during recrystallization of crude Cd[(OPPh2)2N]2 (7). A monomeric structure with a tetrahedral
CdS4 core is found for 1, whereas 4 contains discrete dimers formed through two O,O0, S-bimetallictriconnective ligand units result-
ing in distorted trigonal bipyramidal CdO3S2 cores. In the dinuclear compound 7ÆH2O the Cd atoms are also bridged by two
O,O0,O0-bimetallic triconnective ligands, but the coordination of the metal centres is completed by a bridging water molecule to
givedistorted octahedral CdO6 cores. In the trimetallic unit of 8 the K atom is accommodated in the cavity described by the oxygen
atoms of three ligand units which bridge the Cd atoms. The remaining two ligands are each one chelating a Cd atom, thus resulting
in distorted square pyramidal CdO5 cores.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Cadmium complexes; Tetraorganodichalcogenoimidodiphosphinato ligands; X-ray structure
1. Introduction
als, including group 12 elements, have been reported and
a large diversity of coordination patterns observed in
inorganic and organometallic compounds [1].
Dichalcogenoimidodiphosphinato anions, ½ðXPR2Þ
ðYPR02ÞNꢀꢁ (Scheme 1, a), are versatile ligands able to
adjust to various coordination geometries required by
metal centres, due to the large bite and high flexibility
of the XPNPY skeleton. Complexes of main group met-
For Group 12 elements, inorganic zinc complexes,
Zn½ðXPR2ÞðYPR02ÞNꢀ [2–8] as well as both inorganic
2
and organometallic derivatives of cadmium(II) [2,3,7,9]
and mercury(II) [3,10–15] are known. All inorganic cad-
mium(II) complexes characterized so far are of the type
Cd[(XPR2)2N]2, i.e., containing the same chalcogen
(X = S, Se) and organic groups (R = iPr, Ph) attached
to the phosphorus atoms of the ligand unit. Molecular
*
Corresponding author. Tel.: +98 40 264 193 833; fax: +98 40 64 190
818.
E-mail address: ancas@chem.ubbcluj.ro (A. Silvestru).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.04.046

M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
3725
instrument (1H, 200 MHz; 13C, 50.3 MHz; 31P,
81.0 MHz) for compounds 1, 3, 4, 6, and on a VARIAN
GEMINI 300S instrument (1H, 300 MHz; 13C,
75.4 MHz; 31P, 121.4 MHz) for compounds 2, 5, 7.
The chemical shifts are reported in d units (ppm) relative
to the residual peak of solvent (ref. CHCl3: 1H 7.26, 13
C
77.0 ppm) and H3PO4 85%, respectively. Mass spectra
(EI) were recorded with FINNIGAN MAT CH7 or
FINNIGAN MAT 8222 spectrometers. Infrared spectra
were recorded in the 4000–400 cmꢁ1 range as KBr discs
on a PERKIN ELMER FT-IR SPEKTRUM 1000 spec-
trometer and are reported in cmꢁ1. Elemental analyses
were performed by Facultatea de Farmacie, Universita-
tea de Medicina si Farmacie ‘‘Iuliu Hatieganu’’, Cluj-
Napoca (Romania).
Scheme 1.
structures were established for three complexes and in all
cases discrete monomeric molecules were found in the so-
lid state; the ligands exhibiting an X,X-monometallic
biconnective (Scheme 1, b) coordination pattern thus
resulting in a distorted tetrahedral environment of the
metal atom surrounded by soft donor atoms (CdX4 core).
Our interest is focused on the coordination pattern of
a variety of tetraorganodichalcogenoimidodiphosphi-
nato ligands towards cadmium and the influence which
might arise from the presence of hard donors, i.e., oxy-
gen atoms, and/or different organic substituents at-
tached to the phosphorus atoms of the ligand unit.
The presence of oxygen atoms as donor sites in the li-
gand unit is expected to result in supramolecular associ-
ations in the solid state based on bridging ligand
moieties (Scheme 1, c) and increased coordination num-
ber at the cadmium centres. A well-known example is
the structure of the bis(acetylacetonato)cadmium(II)
analogue which is comprised of linear chains of cad-
mium atoms bridged by bimetallic triconnective ligand
units, thus resulting in octahedral CdO6 cores [16].
We report here on the synthesis and spectroscopic
characterization of some new cadmium(II) complexes
2.2. Syntheses
2.2.1. Preparation of Cd[(SPMe2)2N]2 (1)
A reaction mixture of CdCl2 (0.150 g, 0.82 mmol) and
K[(SPMe2)2N] (0.392 g, 1.64 mmol) in 50 mL toluene
was stirred for 6 h at reflux. The resulting KCl was fil-
tered off. The solvent was removed at reduced pressure
and the resulting white powder was washed with hexane
and dried in vacuum. Yield: 0.22 g (55%), m.p. 164 ꢁC.
Anal. Calc. for C8H24CdN2P4S4: C, 18.74; H, 4.72; N,
5.46. Found: C, 18.53; H, 4.78; N, 5.34%. FT-IR
1
(cmꢁ1): mas(P2N) 1209vs; m(PS) 525m, 505s. H NMR:
d 1.89d [CH3, 2J(PH) 12.0 Hz]. 13C NMR: d 27.26d
[CH3, 1J(PC) 78.4 Hz]. 31P NMR: d 45.5s. MS (EI,
70 eV, 310 ꢁC): m/z (%) 514 (94) [M+]; 499 (72)
[M+ ꢁ Me]; 314 (94) [M+ ꢁ (SPMe2)2N]; 200 (100)
[(SPMe2)2N+]; 170 (32) [(SPMe)2N+]; 106 (33)
[(PMe)2N+].
of the type Cd½ðXPR2ÞðYPR02ÞNꢀ as well as the crystal
2.2.2. Preparation of Cd[(SPPh2)2N]2 (2)
2
and molecular structure of Cd[(SPMe2)2N]2 (1), Cd-
[(OPMe2)(SPPh2)N]2 (4) and [Cd2{(OPPh2)2N}4(H2O)]
(7ÆH2O). The structure of a serendipitous product,
K[Cd2{(OPPh2)2N}5] (8), crystals of which were isolated
during the recrystallization of crude Cd[(OPPh2)2N]2, is
also reported.
2 was obtained as above from CdCl2 (0.072 g,
0.39 mmol) and K[(SPPh2)2N] (0.38 g, 0.78 mmol).
Yield: 0.24 g (60%), m.p. 186 ꢁC. Anal. Calc. for
C48H40CdN2P4S4: C, 57.12; H, 3.99; N, 2.78. Found:
1
C, 56.93; H, 4.05; N 2.56%. H NMR: d 7.32m [24H,
C6H5-meta + para]; 7.85dd [16H, C6H5-ortho, 3J(PH)
3
13.0, J(HH) 6.6 Hz,]. 31P NMR: d 39.1s.
2. Experimental
2.2.3. Preparation of Cd[(SPMe2)(SPPh2)N]2 (3)
3 was obtained as above from CdCl2 (0.14 g,
0.76 mmol)
and
K[(SPMe2)(SPPh2)N]
(0.552 g,
2.1. General methods
1.52 mmol). Yield: 0.24 g (40%), m.p. 134–135 ꢁC. Anal.
Calc. for C28H32CdN2P4S4: C, 44.19; H, 4.24; N, 3.68.
Found: C, 44.05; H, 4.01; N, 3.34%. FT-IR (cmꢁ1):
mas(P2N) 1221vs, 1203vs; m(PhPS) 568s; m(MePS) 515s.
The potassium salts were prepared according to liter-
ature methods: K[(SPMe2)2N] [17], K[(SPPh2)2N] [18],
K[(SPMe2)(SPPh2)N]
[19],
K[(OPMe2)(SPPh2)N],
2
1H NMR: d 1.83d [12H, CH3, J(PH) 13.3 Hz]; 7.37m
K[(OPPh2)(SPMe2)N] [20], K[(OPPh2)(SPPh2)N] [21],
K[(OPPh2)2N] [22]. Solvents were dried and freshly dis-
tilled under argon prior to use. CdCl2 was commercially
available. NMR spectra were recorded at room temper-
ature, in CDCl3 solutions, on a BRUKER DPX 200
[12H, C6H5-meta + para]; 7.82ddd [8H, C6H5-ortho,
3
4
3J(PH) 14.0, J(HH) 6.8, J(HH) 2.0 Hz]. 13C NMR: d
26.87dd [CH3, 1J(PC) 77.1, 3J(PC) 4.9 Hz]; 128.07d
[Cm, 3J(PC) 13.6 Hz]; 130.76d [Co, 2J(PC) 11.1 Hz];

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M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
130.84 d [Cp, 4J(PC) 2.5 Hz]; 138.04dd [Ci, 1J(PC) 110.4,
3J(PC) 4.9 Hz]. 31P NMR: d 37.7d [Ph2PS, 2J(PP)
10.6 Hz]; 44.3d [Me2PS, 2J(PP) 10.1 Hz]. MS (EI
70 eV, 299 ꢁC): m/z (%) 762 (72) [M+]; 747 (9)
[M+ ꢁ Me]; 671 (8) [M+ ꢁ Me ꢁ Ph]; 653 (41)
[M+ ꢁ Ph ꢁ S]; 438 (100) [M+ ꢁ (SPMe2)(SPPh2)N];
324 (82) [(SPMe2)(SPPh2)N+]; 292 (32) [M+ ꢁ (PMe2)-
(SPPh2)N]; 260 (24) [(PMe2)(PPh2)N+].
1H NMR: d 7.28m [24H, C6H5-meta + para]; 7.66ddd
3 3 4
[8H, P(S)C6H5-ortho, J(PH) 12.6, J(HH) 7.5, J(HH)
1.6 Hz]; 7.83ddd [8H, P(O)C6H5-ortho, 3J(PH) 14.2,
4
3J(HH) 7.6, J(HH) 1.8 Hz]. 13C NMR: d 128.28d [Cm,
3
3J(PC) 12.9 Hz]; 128.40d [Cm, J(PC) 13.4 Hz]; 130.85d
[Cp, 4J(PC) 3.0 Hz]; 131.13d [Cp, 4J(PC) 3.0 Hz];
131.21d [Co, 2J(PC) 10.9 Hz]; 131.56d [Co, 2J(PC)
10.4 Hz]; 137.44dd [Ci, P(O)C6H5, 1J(PC) 135.3,
1
3J(PC) 4.9 Hz]; 138.59dd [Ci, P(S)C6H5, J(PC) 110.5,
2.2.4. Preparation of Cd[(OPMe2)(SPPh2)N]2 (4)
4 was obtained as above from CdCl2 (0.150 g,
3J(PC) 4.9 Hz]. 31P NMR: d 26.0d [Ph2PO, 2J(PP)
3.0 Hz]; 34.5s,br [Ph2PS]. MS (EI, 70 eV, 272 ꢁC): m/z
(%) 978 (31) [M+]; 869 (53) [M+ ꢁ Ph ꢁ S]; 546 (42)
[M+ ꢁ [(SPPh2)(OPPh2)N]; 433 (32) [(SPPh2)(OPPh2)-
NH+]; 400 (100) [(PPh2)(OPPh2)N+].
0.82 mmol)
and
K[(OPMe2)(SPPh2)N]
(0.569 g,
1.64 mmol). Yield: 0.49 g (82%), m.p. 214 ꢁC. Anal.
Calc. for C28H32CdN2O2P4S2: C, 46.13; H, 4.42; N,
3.84. Found: C, 45.96; H, 4.23; N, 3.67%. FT-IR
(cmꢁ1): mas(P2N) 1208vs; m(PO) 1098vs; m(PS) 569vs.
1H NMR: d 1.29dd [12H, CH3, 2J(PH) 13.9, 4J(PH)
0.9 Hz]; 7.34m [12H, C6H5-meta + para]; 7.86ddd [8H,
2.2.7. Preparation of Cd[(OPPh2)2N]2 (7)
7 was obtained as a colorless powder following the
similar procedure as above, from CdCl2 (0.116 g,
0.63 mmol) and K[(OPPh2)2N] (0.578 g, 1.27 mmol).
Yield: 0.47 g (78%), m.p. 245 ꢁC. Anal. Calc. for
C48H40CdN2O4P4: C, 61.00; H, 4.27; N, 2.96. Found:
C, 61.23; H, 4.54; N, 2.83%. FT-IR (cmꢁ1): mas(P2N)
1223vs; m(PO) 1127vs, 1094vs. 1H NMR: d 7.04m
[16H, C6H5-meta]; 7,20m [8H, C6H5-para]; 7.62dd
[16H, C6H5-ortho, 3J(PH) 11.9, 3J(HH) 7.9 Hz]. 13C
NMR: d 127.45d [Cm, 3J(PC) 12.5 Hz]; 129.61s [Cp];
131.27d [Co, 2J(PC) 10.2 Hz]; 138.47d [Ci, 1J(PC)
134.9 Hz]. 31P NMR: d 25.1s,br [Ph2PO]. MS (EI,
70 eV, 367 ꢁC): m/z (%) 946 (97) [M+]; 869 (26)
[M+ ꢁ Ph]; 530 (22) [M+ ꢁ (OPPh2)2N]; 416 (51)
[(OPPh2)2N+]; 201 (100) [OPPh2+].
3
3
4
C6H5-ortho, J(PH) 13.9, J(HH) 7.6, J(HH) 1.5 Hz].
13C NMR: d 20.33dd [CH3, 1J(PC) 93.4, 3J(PC)
4.6 Hz]; 127.85d [Cm, 3J(PC) 13.4 Hz]; 130.30d [Cp,
2
4J(PC) 2.8 Hz]; 130.72d [Co, J(PC) 11.1 Hz]; 139.22dd
[Ci, 1J(PC) 108.6, 3J(PC) 4.6 Hz]. 31P NMR: d 33.7s
[Ph2PS]; 42.2s [Me2PO]. MS (EI, 70 eV, 310 ꢁC): m/z
(%) 730 (100) [M+], 715 (12) [M+ ꢁ Me]; 653 (12)
[M+ ꢁ Ph]; 639 (8) [M+ ꢁ Me ꢁ Ph]; 621 (46)
[M+ ꢁ Ph ꢁ S]; 454 (5) [Cd(S)[(OPMe2)(SPPh2)N]+];
422 (39) [M+ ꢁ (SPPh2)(OPMe2)N]; 308 (31) [(SPPh2)-
(OPMe2)N+]; 292 (8) [(PMe2)(SPPh2)N+]; 276 (51)
[(OPMe2)(PPh2)N+].
2.2.5. Preparation of Cd[(OPPh2)(SPMe2)N]2 (5)
5 was obtained as above from CdCl2 (0.125 g,
2.3. Crystal structure determinations
0.68 mmol)
and
K[(OPPh2)(SPMe2)N]
(0.472 g,
1.36 mmol). Yield: 0.38 g (76%), m.p. 253 ꢁC. Anal.
Calc. for C28H32CdN2O2P4S2: C, 46.13; H, 4.42; N,
3.84. Found: C, 45.84; H, 4.63; N, 3.92%. FT-IR
(cmꢁ1): mas(P2N) 1240vs; m(PO) 1166vs; m(PS) 521vs.
Colourless, block crystals of Cd[(SPMe2)2N]2 (1),
Cd[(OPMe2)(SPPh2)N]2 (4), [Cd2{(OPPh2)2N}4(H2O)]
(7ÆH2O) and K[Cd2{(OPPh2)2N}5] (8) were mounted
on glass fibres. Data were collected at room temperature
(298 K) on an Enraf Nonius KappaCCD area detector
diffractometer, with u and x scans chosen to give a com-
plete asymmetric unit, using graphite-monochromated
2
1H NMR: d 1.73d [12H, CH3, J(PH) 14.3 Hz]; 7.40m
[12H, C6H5-meta + para]; 7.99dd [8H, C6H5-ortho,
3J(PH) 14.0, 3J(HH) 7.3 Hz]. 31P NMR: d 28.4s
[Ph2PO]; 51.2s [Me2PS]. MS (EI, 70 eV, 282 ꢁC): m/z
(%) 730 (100) [M+]; 715 (12) [M+ ꢁ Me]; 653 (12)
[M+ ꢁ Ph]; 639 (7) [M+ ꢁ Me ꢁ Ph]; 621 (37)
[M+ ꢁ Ph ꢁ S]; 454 (6) [Cd(S)(SPMe2)(OPPh2)N+]; 422
(38) [M+ ꢁ (SPMe2)(OPPh2)N]; 308 (27) [(SPMe2)-
(OPPh2)N+]; 292 (8) [(SPMe2)(PPh2)N+]; 276 (47)
[(PMe2)(OPPh2)N+].
˚
Mo Ka radiation (k = 0.71073 A). Data collection and
cell refinement [23] gave cell constants corresponding
to tetragonal (for 1), monoclinic (for 4) and triclinic
(for 7ÆH2O and 8) cells whose dimensions are given in
Table 1 along with other experimental parameters.
An absorption correction was applied [24] which re-
sulted in transmission factors ranging from 0.8441 to
0.7788 for 1, 0.8285 to 0.7580 for 4, 0.9093 and 0.8816
for 7ÆH2O, and 0.8861 to 0.8359 for 8. The structures
were solved by direct methods [25]. All of the non-
hydrogen atoms were treated anisotropically and hydro-
gen atoms were included in idealized positions with
isotropic thermal parameters set at 1.2 times that of
the carbon atom to which they were attached. The final
cycle of full-matrix least-squares refinement [26] con-
2.2.6. Preparation of Cd[(OPPh2)(SPPh2)N]2 (6)
6 was obtained as above from CdCl2 (0.112 g,
0.61 mmol)
and
K[(OPPh2)(SPPh2)N]
(0.575 g,
1.22 mmol). Yield: 0.40 g (68%), m.p. 197 ꢁC. Anal.
Calc. for C48H40CdN2O2P4S2: C, 58.99; H, 4.13; N,
2.87. Found: C, 59.23; H, 4.34; N, 2.67%. FT-IR
(cmꢁ1): mas(P2N) 1248vs; m(PO) 1123vs; m(PS) 571vs.

M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
3727
Table 1
Crystallographic data for Cd[(SPMe2)2N]2 (1), Cd[(OPMe2)(SPPh2)N]2 (4), [Cd2{(OPPh2)2N}4(H2O)] (7ÆH2O) and K[Cd2{(OPPh2)2N}5] (8)
1
4
7ÆH2O
8
Empirical formula
Formula weight
Crystal size (mm)
Temperature (K)
C8H24CdN2P4S4
512.81
C28H32CdN2O2P4S2
728.96
C96H82Cd2N4O9P8
1908.22
C120H100Cd2KN5O10P10
2345.65
0.15 · 0.10 · 0.10
298(2)
0.30 · 0.20 · 0.20
298(2)
0.71073
0.20 · 0.15 · 0.15
298(2)
0.71073
0.30 · 0.25 · 0.20
298(2)
0.71073
˚
Wavelength (A)
0.71073
tetragonal
P41212
Crystal system
Space group
monoclinic
P21/n
triclinic
ꢀ
triclinic
ꢀ
P1
P1
˚
a (A)
9.952(1)
9.952(1)
20.934(4)
90.00
15.011(3)
11.814(2)
20.366(4)
90
14.376(3)
15.927(3)
22.209(4)
92.39(3)
100.87(3)
109.00(3)
4693(2)
13.606(3)
18.585(4)
24.979(5)
104.13(3)
95.61(3)
110.77(3)
5608(2)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90.00
90.00
2073(1)
109.33(3)
90
3409(1)
3
˚
V (A )
Z
4
1.643
4
1.421
2
1.350
2
1.389
Dcalc (Mg mꢁ3
)
l (mmꢁ1
F(000)
)
1.754
1032
0.978
1480
0.646
1948
0.620
2400
h Range for data collections (ꢁ)
Maximum and minimum transmission
Reflections collected
3.05–27.52
0.8441 and 0.7788
5437
2.95–30.74
0.8285 and 0.7580
27724
2.99–25.03
0.9093 and 0.8816
55349
2.96–25.02
0.8861 and 0.8359
49877
Independent reflections [Rint
Refinement method
]
2219 [0.0339]
8843 [0.0467]
16379 [0.0789]
19627 [0.0631]
full-matrix least-squares on F2
Data/restraints/parameters
Goodness-of-fit on F2
2219/0/92
1.036
8843/0/357
0.992
16 379/0/1109
1.027
19 627/0/1334
1.018
Final R indices [F2 > 4r(F2)] R1, wR2
R indices (all data) R1, wR2
0.0297, 0.0616
0.0384, 0.0651
0.0116(6)
0.0395, 0.0850
0.0816, 0.0981
0.0009(2)
0.0594, 0.1486
0.1050, 0.1699
0.0010(3)
0.0615, 0.1652
0.0995, 0.1896
Extinction coefficiꢁen3 t
˚
Final K-map (e A
)
0.399, ꢁ0.571
0.490, ꢁ0.515
1.734, ꢁ1.216
2.723, ꢁ1.585
verged (largest parameter shift was 0.001 times its esd).
The absolute structure parameter for 1 was ꢁ0.10(6).
Only one of the phenyl groups in 7ÆH2O was success-
fully modelled for disorder, even though the thermal
parameters for some carbon atoms were large. The
drawings were created with the DIAMOND program [27].
All compounds were isolated as air-stable, colourless,
crystalline products. In addition to the desired com-
pound 7, crystals of a species containing K:Cd in a 1:2
ratio, K[Cd2{(OPPh2)2N}5] (8), were also isolated; pre-
sumably resulting from
7 reacting further with
K[(OPPh2)2N]. This contrasts with the formation of
the ionic acetylacetonato analogue, K[Cd{(OCMe)2-
CH}3](H2O), whose crystal structure was previously re-
ported [28]. An attempt to prepare 8 using a 2:5 molar
ratio between CdCl2 and K[(OPPh2)2N] failed; the ana-
lytical data (IR, NMR, MS) for the isolated crystalline
product being identical to those of a sample of 7.
Compounds 1–7 were characterized by infrared and
multinuclear NMR (1H, 13C and 31P) spectroscopy, as
well as mass spectrometry. The analytical data are con-
sistent with the anticipated formulas.
In the IR spectra recorded as KBr discs bands were
assigned for mas(P2N), m(PO) and m(PS) stretching vibra-
tions by comparison with the free ðXPR2ÞðYPR02ÞNH
acids and their alkali metal salts [17–21]. The presence
of strong absorbtions in the regions 1250–1200
[mas(P2N)], 1130–1100 [m(PO)] and 570–500 cmꢁ1 [m(PS)]
and the absence of strong absorbtions characteristic
for the free acids around 2700–2600 [m(NH)] and 950–
900 cmꢁ1 [mas(P2NH)], indicates that the ligands moieties
are coordinated to the metal centre in the deprotonated
form through both chalcogen atoms in the solid state.
3. Results and discussion
3.1. Preparation and spectroscopic studies
Bis(tetraorganodichalcogenoimidodiphosphinato) cad-
mium(II) 1–7 were prepared in good yields according to
Scheme 2, by reacting stoichiometric amounts of CdCl2
and the potassium salt of the appropriate tetraorgano-
dichalcogenoimidodiphosphinate in boiling toluene.
Scheme 2. The synthesis of complexes 1–7.

3728
M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
Table 2
The NMR spectra of compounds 1–7 show the ex-
pected resonances for the compounds with the general
˚
Important interatomic distances (A) and angles (ꢁ) for Cd[(SPMe2)2N]2
(1) and Cd[(OPMe2)(SPPh2)N]2 (4)
formula Cd½ðXPR2ÞðYPR20 ÞNꢀ and suggest that the or-
2
1a
ganic groups attached to the same phosphorus atom are
equivalent on the NMR time scale at room temperature.
The expected splitting patterns due to phosphorus–pro-
ton and phosphorus–carbon couplings were observed
both in 1H and 13C NMR spectra. The 31P NMR spectra
exhibit either one (for compounds 1, 2 and 7) or two res-
onances (for compounds 3–6), in accordance with the
presence of two either equivalent or non-equivalent
phosphorus atoms in the ligand unit. However, only
for compounds 3 (both signals) and 6 (the resonance
for the PO atoms) could the phosphorus–phosphorus
couplings be observed. The magnitude of the chemical
shifts suggests that both chalcogen atoms of a ligand
unit are involved in coordination to the metal centre
in solution [1], as suggested by IR spectra for solid state.
The EI mass spectra of compounds 1–7 exhibit sig-
nals of high intensity corresponding to the [M+] molec-
ular ions. No fragments with a higher mass than the
expected molecular mass (m/z) were observed for the
Cd½ðXPR2ÞðYPR0 ÞNꢀ species. In the FAB+ mass spec-
Cd(1)–S(1)
Cd(1)–S(2)
P(1)–S(1)
P(2)–S(2)
P(1)–N(1)
P(2)–N(1)
2.516(1)
2.538(1)
2.026(1)
2.022(1)
1.586(3)
1.586(3)
S(1)–Cd(1)–S(2)
S(1)–Cd(1)–S(1a)
S(1)–Cd(1)–S(2a)
S(2)–Cd(1)–S(2a)
Cd(1)–S(1)–P(1)
S(1)–P(1)–N(1)
P(1)–N(1)–P(2)
S(2)–P(2)–N(1)
Cd(1)–S(2)–P(2)
105.32(3)
105.13(4)
114.32(3)
112.43(4)
99.47(4)
115.8(1)
131.3(2)
117.2(1)
95.88(4)
4b
Cd(1)–S(1a)
Cd(1)–O(1)
Cd(1)–O(1a)
Cd(1)–S(2)
Cd(1)–O(2)
P(1)–O(1)
P(2)–S(1)
P(1)–N(1)
P(2)-N(1)
P(3)–O(2)
P(4)–S(2)
P(3)–N(2)
P(4)–N(2)
2.536(1)
2.215(2)
2.415(2)
2.523(1)
2.257(2)
1.519(2)
2.022(1)
1.601(2)
1.596(2)
1.506(2)
2.022(1)
1.581(3)
1.576(3)
2
2
trum of 7 a fragment of m/z 1475 (8%) was observed.
This fragment was assigned to ½Cd2½ðOPPh2Þ Nꢀ þꢀ, pre-
2
3
sumably arising from the fragmentation of the dimeric
species 7. But it could similarly arise from 8.
3.2. Crystal and molecular structures of 1, 4, 7ÆH2O and 8
O(1a)–Cd(1)–O(2)
O(1a)–Cd(1)–O(1)
O(1a)–Cd(1)–S(1a)
O(1a)–Cd(1)–S(2)
O(1)–Cd(1)–S(1a)
S(1a)–Cd(1)–S(2)
O(2)–Cd(1)–O(1)
O(2)–Cd(1)–S(1)0
O(2)–Cd(1)–S(2)
O(1)–Cd(1)–S(2)
Cd(1)–O(1)–Cd(1a)
Cd(1)–O(1)–P(1)
O(1)–P(1)–N(1)
P(1)–N(1)–P(2)
S(1)–P(2)–N(1)
Cd(1a)–S(1)–P(2)
Cd(1)–O(2)–P(3)
O(2)–P(3)–N(2)
P(3)–N(2)–P(4)
S(2)–P(4)–N(2)
Cd(1)–S(2)–P(4)
Cd(1)–O(1a)–P(1a)
a
166.67(7)
74.90(6)
88.93(5)
87.99(5)
116.38(5)
126.11(3)
91.84(7)
95.96(6)
98.98(6)
114.53(6)
105.10(6)
136.2(1)
113.5(1)
126.2(1)
117.42(8)
96.05(4)
125.2(1)
117.7(1)
135.2(2)
120.4(1)
104.93(4)
117.78(9)
Suitable crystals for X-ray diffraction analysis were
grown by solvent diffusion from dichloromethane and
n-hexane (1/4, v/v) and the crystal and molecular struc-
tures of 1, 4, 7ÆH2O and 8 were determined, revealing
various coordination patterns of the dichalcogeno-
imidodiphosphinato ligands towards cadmium. Impor-
tant molecular parameters are given in Tables 2 and 3,
and the structures of 1, 4, 7ÆH2O and 8 with the atom
numbering schemes are shown in Figs. 1–4.
The crystal of 1 consists of discrete monomeric units
of Cd[(SPMe2)2N]2 (Fig. 1) separated by normal van der
Waals distances, similar to those found previously for
Cd½ðSPPri2Þ Nꢀ [2], and Cd[(SePR2)2N]2 (R = Pri [7],
2
2
Ph [3]). The Cd atom lies on a twofold axis and the dith-
ioimidodiphosphinato ligands act as symmetric S,
S-monometallic biconnective units, resulting in six-
membered CdS2P2N chelate rings of distorted boat
conformation, with the metal and N(1) atoms in the api-
ces (Table 4). The CdS4 core is tetrahedral [the dihedral
angle between Cd(1)S(1)S(2) and Cd(1)S(1a)S(2a) is
94.3ꢁ], with S–Cd–S angles ranging from 105.13(4)ꢁ to
114.32(3)ꢁ. The cadmium–sulfur distances Cd(1)–S(1)
Symmetry equivalent positions (y, x, ꢁz) are given by an ‘‘a’’.
b
Symmetry equivalent position (ꢁx, 1 ꢁ y, 2 ꢁ z) given by an ‘‘a’’.
have crystallographically imposed inversion symmetry
(Fig. 2). Two metal centres are bridged by two ligand
˚
units [Cd(1)–O(1) 2.215(2), Cd(1)–S(1a) 2.536(1) A]. In
addition, strong transannular Cd(1)–O(1a) interactions
˚
2.516(1) and Cd(2)–S(2) 2.538(1) A are similar to those
i
˚
found in Cd½ðSPPr2Þ Nꢀ [2.514(2), 2.531(2) A] [2].
2
2
By contrast, the crystals of the monothio derivative
Cd[(OPMe2)(SPPh2)N]2 (4) contain discrete dimers that
˚
[2.415(2) A] are also established, and thus the bridging

M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
3729
Table 3
Table 3 (continued)
˚
Important interatomic distances (A) and angles (ꢁ) for
[Cd2{(OPPh2)2N}(H2O)] (7ÆH2O) and K[Cd2{(OPPh2)2N}] (8)
7ÆH2O
O(1)–P(1)–N(1)
P(1)–N(1)–P(2)
O(2)–P(2)–N(1)
P(2)–O(2)–Cd(1)
P(7)–O(7)–Cd(2)
O(7)–P(7)–N(4)
P(7)–N(4)–P(8)
O(8)–P(8)–N(4)
P(8)–O(8)–Cd(2)
P(3)–O(3)–Cd(1)
O(3)–P(3)–N(2)
P(3)–N(2)–P(4)
O(4)–P(4)–N(2)
P(4)–O(4)–Cd(1)
P(5)–O(5)–Cd(2)
O(5)–P(5)–N(3)
P(5)–N(3)–P(6)
O(6)–P(6)–N(3)
P(6)–O(6)–Cd(2)
P(6)–O(6)–Cd(1)
P(4)–O(4)–Cd(2)
118.5(2)
7ÆH2O
127.9(3)
118.2(2)
128.3(2)
120.2(2)
117.7(3)
129.0(3)
118.4(3)
124.7(2)
119.9(2)
117.4(2)
128.6(3)
115.9(2)
116.3(2)
119.6(2)
116.9(2)
135.4(3)
117.7(2)
118.1(2)
143.2(2)
149.9(2)
Cd(1)–O(1)
Cd(1)–O(2)
Cd(1)–O(3)
Cd(1)–O(4)
Cd(1)–O(6)
Cd(1)–O(9)
Cd(2)–O(7)
Cd(2)–O(8)
Cd(2)–O(5)
Cd(2)–O(6)
Cd(2)–O(4)
Cd(2)–O(9)
P(1)–O(1)
P(2)–O(2)
P(1)–N(1)
P(2)–N(1)
P(7)–O(7)
P(8)–O(8)
P(7)–N(4)
P(8)–N(4)
P(3)–O(3)
P(4)–O(4)
P(3)–N(2)
P(4)–N(2)
P(5)–O(5)
P(6)–O(6)
P(5)–N(3)
P(6)–N(3)
2.218(4)
2.198(3)
2.167(4)
2.357(4)
2.235(4)
2.787(5)
2.233(4)
2.188(4)
2.204(4)
2.331(3)
2.312(4)
2.459(5)
1.509(4)
1.508(4)
1.589(5)
1.587(5)
1.529(4)
1.506(4)
1.550(5)
1.594(5)
1.514(4)
1.518(4)
1.588(5)
1.584(5)
1.510(4)
1.531(4)
1.582(4)
1.567(5)
8
Cd(1)–O(1)
Cd(1)–O(2)
Cd(1)–O(3)
Cd(1)–O(5)
Cd(1)–O(7)
Cd(2)–O(9)
Cd(2)–O(10)
Cd(2)–O(6)
Cd(2)–O(4)
Cd(2)–O(8)
P(1)–O(1)
P(2)–O(2)
P(1)–N(1)
P(2)–N(1)
P(9)–O(9)
P(10)–O(10)
P(9)–N(5)
P(10)–N(5)
P(3)–O(3)
P(4)–O(4)
P(3)–N(2)
P(4)–N(2)
P(6)–O(6)
P(5)–O(5)
P(6)–N(3)
P(5)–N(3)
P(7)–O(7)
P(7)–N(4)
P(8)–O(8)
P(8)–N(4)
K(1)–O(3)
K(1)–O(5)
K(1)–O(7)
K(1)–O(6)
K(1)–O(4)
K(1)–O(8)
2.207(4)
2.221(4)
2.251(3)
2.262(4)
2.250(3)
2.163(4)
2.216(4)
2.227(4)
2.270(3)
2.229(4)
1.511(4)
1.501(4)
1.590(5)
1.578(5)
1.511(4)
1.504(4)
1.565(5)
1.590(5)
1.511(3)
1.505(3)
1.595(5)
1.588(5)
1.513(4)
1.516(4)
1.580(5)
1.583(5)
1.520(3)
1.585(5)
1.502(3)
1.585(5)
2.470(4)
2.391(4)
2.410(4)
2.418(4)
2.364(4)
2.444(4)
O(2)–Cd(1)–O(4)
O(8)–Cd(2)–O(6)
O(2)–Cd(1)–O(1)
O(2)–Cd(1)–O(3)
O(2)–Cd(1)–O(6)
O(8)–Cd(2)–O(4)
O(8)–Cd(2)–O(5)
O(8)–Cd(2)–O(7)
O(4)–Cd(1)–O(1)
O(4)–Cd(1)–O(3)
O(4)–Cd(1)–O(6)
O(6)–Cd(2)–O(7)
O(6)–Cd(2)–O(5)
O(6)–Cd(2)–O(4)
O(1)–Cd(1)–O(3)
O(3)–Cd(1)–O(6)
O(6)–Cd(1)–O(1)
O(7)–Cd(2)–O(5)
O(5)–Cd(2)–O(4)
O(4)–Cd(2)–O(7)
O(9)–Cd(1)–O(3)
O(9)–Cd(1)–O(1)
O(9)–Cd(1)–O(2)
O(9)–Cd(1)–O(6)
O(9)–Cd(1)–O(4)
O(9)–Cd(2)–O(5)
O(9)–Cd(2)–O(7)
O(9)–Cd(2)–O(8)
O(9)–Cd(2)–O(4)
O(9)–Cd(2)–O(6)
Cd(1)–O(4)–Cd(2)
Cd(1)–O(9)–Cd(2)
Cd(1)–O(6)–Cd(2)
P(1)–O(1)–Cd(1)
163.8(1)
169.9(1)
90.7(1)
102.5(1)
92.0(1)
98.6(1)
98.9(1)
93.2(2)
88.0(1)
93.6(1)
78.9(1)
87.0(1)
91.0(1)
77.9(1)
101.4(2)
116.5(2)
140.4(2)
100.3(2)
98.0(1)
156.4(2)
156.7(1)
66.7(2)
97.7(2)
73.8(1)
67.0(1)
168.0(2)
85.9(2)
90.9(2)
73.6(1)
79.0(2)
93.2(1)
80.3(1)
95.9(1)
129.3(2)
O(7)–Cd(1)–O(1)
O(7)–Cd(1)–O(2)
O(7)–Cd(1)–O(3)
O(7)–Cd(1)–O(5)
98.5(1)
123.5(2)
83.8(1)
83.1(1)
(continued on next page)

3730
M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
Table 3 (continued)
8
O(7)–Cd(1)–O(5)
O(8)–Cd(2)–O(10)
O(8)–Cd(2)–O(9)
O(8)–Cd(2)–O(6)
O(8)–Cd(2)–O(4)
O(1)–Cd(1)–O(2)
O(2)–Cd(1)–O(3)
O(3)–Cd(1)–O(5)
O(5)–Cd(1)–O(1)
O(1)–Cd(1)–O(3)
O(2)–Cd(1)–O(5)
O(9)–Cd(2)–O(10)
O(10)–Cd(2)–O(6)
O(6)–Cd(2)–O(4)
O(4)–Cd(2)–O(9)
O(9)–Cd(2)–O(6)
O(10)–Cd(2)–O(4)
O(3)–K(1)–O(5)
O(5)–K(1)–O(7)
O(7)–K(1)–O(3)
O(4)–K(1)–O(6)
O(6)–K(1)–O(8)
O(8)–K(1)–O(4)
O(3)–K(1)–O(4)
O(7)–K(1)–O(8)
O(3)–K(1)–O(6)
O(3)–K(1)–O(8)
O(7)–K(1)–O(4)
O(5)–K(1)–O(6)
O(5)–K(1)–O(4)
O(5)–K(1)–O(8)
O(7)–K(1)–O(6)
P(1)–O(1)–Cd(1)
O(1)–P(1)–N(1)
P(1)–N(1)–P(2)
O(2)–P(2)–N(1)
P(2)–O(2)–Cd(1)
P(9)–O(9)–Cd(2)
O(9)–P(9)–N(5)
P(9)–N(5)–P(10)
O(10)–P(10)–N(5)
P(10)–O(10)–Cd(2)
P(3)–O(3)–Cd(1)
O(3)–P(3)–N(2)
P(3)–N(2)–P(4)
O(4)–P(4)–N(2)
P(4)–O(4)–Cd(2)
P(5)–O(5)–Cd(1)
O(5)–P(5)–N(3)
P(5)–N(3)–P(6)
O(6)–P(6)–N(3)
P(6)–O(6)–Cd(2)
P(7)–O(7)–Cd(1)
O(7)–P(7)–N(4)
P(7)–N(4)–P(8)
P(8)–O(8)–Cd(2)
O(8)–P(8)–N(4)
83.1(1)
105.9(2)
117.5(1)
83.1(1)
84.6(1)
88.3(1)
96.1(1)
82.9(1)
90.6(1)
172.8(2)
153.3(1)
89.8(1)
93.0(1)
81.1(1)
91.5(1)
157.5(1)
167.3(2)
75.8(1)
77.1(1)
76.0(1)
75.4(1)
74.9(1)
Fig. 1. ORTEP plot of Cd[(SPMe2)2N]2 (1). The atoms are drawn with
50% probability ellipsoids [symmetry equivalent positions (y, x, ꢁz)
78.1(1)
91.5(1)
87.3(1)
are given by an ‘‘a’’].
141.3(1)
138.7(2)
141.1(2)
88.6(1)
136.0(1)
137.2(1)
135.2(1)
128.7(2)
116.5(3)
127.1(3)
119.0(2)
130.9(2)
132.2(2)
117.0(2)
130.9(3)
118.5(2)
129.4(2)
151.6(2)
116.4(2)
134.4(3)
116.2(2)
144.9(2)
132.0(2)
116.6(2)
132.9(3)
116.3(2)
134.0(2)
146.8(2)
116.8(2)
130.4(3)
146.2(2)
115.3(2)
Fig. 2. ORTEP plot of the dimer association in the crystal of
Cd[(OPMe2)(SPPh2)N]2 (4). The atoms are drawn with 30% probabil-
ity ellipsoids and the hydrogen atoms are omitted [symmetry equiv-
alent positions (ꢁx, 1 ꢁ y, 2 ꢁ z) are given by an ‘‘a’’].
ligands can be regarded as O,O0,S-bimetallic triconnec-
tive units (cf. Cd–O bond lengths range between
˚
2.250(4) and 2.353(4) A in the [Cd(acac)2]n polymer
[16]). This results in a fused tricyclic Cd2O2S2P4N2
system which features a ladder structure with SPNP
fragments placed on opposite sides of the central planar
Cd2O2 core. A similar arrangement was also described
in the crystals of [PhHg{(OPMe2)(SPPh2)N}]2 [15] and

Table 4
Conformation of the six-membered MXYP2N rings (deviations, A) for Cd[(SPMe2)2N]2 (1), Cd[(OPMe2)(SPPh2)N]2 (4), [Cd2{(OPPh2)2N}4(H2O)] (7ÆH2O) and K[Cd2{(OPPh2)2N}5] (8)
˚
1
4
7ÆH2O
8
Chelate ligands, deviations from plane
Cd(1)S(1)S(2)
Cd(1)O(2)P(3)
Cd(1)O(1)O(2)
Cd(2)O(8)P(8)
Cd(1)O(2)P(2)
Cd(2)O(9)O(10)
P(1)
P(2)
N(1)
ꢁ0.909
ꢁ1.695
ꢁ1.932
S(2)
P(4)
N(2)
1.327
1.845
0.925
P(1)
P(2)
N(1)
0.048
0.209
O(7)
P(7)
N(4)
0.675
1.334
0.701
O(1)
P(1)
N(1)
0.255
0.671
0.158
P(9)
P(10)
N(5)
ꢁ0.071
ꢁ0.124
ꢁ0.315
ꢁ0.126
distorted boat
distorted boat
flattened chair
distorted boat
distorted boat
distorted boat
Bridging ligands, deviations from plane
Cd(1)O(1a)S(1a)
Cd(1)O(3)O(4)
Cd(2)O(5)O(6)
K(1)O(3)O(4)
K(1)O(7)O(8)
K(1)O(5)O(6)
P(1a)
P(2a)
N(1a)
1.076
1.707
2.080
P(3)
P(4)
N(2)
ꢁ0.578
ꢁ0.912
ꢁ1.387
P(5)
P(6)
N(3)
ꢁ0.947
ꢁ0.846
ꢁ1.374
P(3)
P(4)
N(2)
ꢁ0.413
ꢁ0.367
ꢁ0.107
P(7)
P(8)
N(4)
0.256
0.253
P(5)
P(6)
N(3)
1.065
0.931
1.621
ꢁ0.121
Distorted boat
distorted boat
distorted boat
chair
chair
distorted boat

3732
M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
˚
O(2) 2.257(2), Cd(1)–S(2) 2.523(1) A]. A distorted trigo-
nal bipyramidal environment around the metal centre is
thus achieved, with the oxygen atoms of the chelated
and bridging ligands in axial positions [O(2)–Cd(1)–
O(1a) 166.7(1)ꢁ] and the equatorial belt formed by the
O(1), S(2) and S(1a) atoms [the Cd(1) atom is displaced
˚
0.244 A from the O(1)S(2)S(1a) plane towards the O(2)
axial atom]. The two CdO2S3 cores of the dinuclear unit
share the common axial–equatorial O(1) ꢂ ꢂ ꢂ O(1a) edge.
The two six-membered CdOSP2N rings in 4 exhibit
boat conformation of variable distortion and with differ-
ent atom types in the apices, i.e., O(2)/P(4) (chelate li-
gand) and Cd(1)/N(1a) atoms (bridging ligand) (Table
4). The large difference in the P–N–P bond angle in
the bridging ligand [126.2(1)ꢁ] compared to the external
one [135.2(2)ꢁ] reflects the flexibility of the OPNPS
skeleton.
Fig. 5. ORTEP plot of K[Cd2{(OPPh2)2N}5] (8). The atoms are drawn
with 30% probability ellipsoids and the hydrogen atoms are omitted.
Compound 7 crystallizes as a water adduct, [Cd2-
{(OPPh2)2N}4(H2O)] (7ÆH2O). The crystal contains
discrete dinuclear units (Fig. 3) in which the structure
of the Cd2[(OPPh2)2N]4 fragment is related to that ob-
served for the dimer of 4, with O,O0-monometallic
biconnective and O,O0,O0-bimetallic triconnective ligand
units. The overall conformation of the Cd2O8P8N4 sys-
tem might be described as cis, i.e., with six-membered
CdO2P2N rings formed by ligands of the same type
placed on the same side of the folded four-membered
Cd2O2 ring (Fig. 4(a)). A similar Mn2O8P8N4 core was
previously described for the dimer Mn2[(OPPh2)2N]4
[30]. This contrasts with the overall trans conformation
of the Cd2O4S4P8N4 system in 4 (i.e., with six-membered
CdO2P2N rings formed by ligands of the same type
placed on the opposite sides of the planar four-mem-
bered Cd2O2 ring) (Fig. 4(b)). The folding of the
Cd2O2 ring [dihedral angle Cd(1)O(4)O(6)/Cd(2)-
O(4)O(6) of 142.9ꢁ] brings the metal centres closer to-
gether in the dinuclear unit of 7ÆH2O than in 4 or in
the related polymeric acetylacetonato derivative [Cd-
(acac)2]n (the nonbonding Cdꢂ ꢂ ꢂCd distances are 3.392;
other two CdO2P2N rings formed by the bridging li-
gands exhibit similar boat conformation, with Cd(1)/
N(2) and Cd(2)/N(3) atoms, respectively, in the apices
(Table 4).
A
few crystals of the unexpected K[Cd2-
{(OPPh2)2N}5] (8) were isolated during the recrystalliza-
tion of 7. The crystal of 8 contains discrete trimetallic
units (Fig. 5) which feature an almost co-linear KCd2
moiety [Cd(1)ꢂ ꢂ ꢂK(1)ꢂ ꢂ ꢂCd(2) 176.9ꢁ]. The Cd atoms
are bridged by three ligand units; their oxygen atoms
describing a cavity in which a potassium cation is
˚
accommodated [K–O range: 2.364(4)–2.470(4) A].
The KO6 core is trigonal prismatic [dihedral angles:
K(1)O(3)O(4)/K(1)O(5)O(6) 120, K(1)O(3)O(4)/K(1)-
O(7)O(8) 122.3, K(1)O(5)O(6)/K(1)O(7)O(8) 117.5ꢁ]
and the distances from the metal centre to the trigonal
˚
bases are equivalent [1.697 and 1.691 A to O(3)O(5)-
O(7) and O(4)O(6)O(8) planes, respectively]. Thus,
the overall coordination pattern of the bridging ligands
can be described as O,O,O0,O0-trimetallic tetra-
connective.
˚
3.678, and 3.719/3.768 A, respectively) [16].
Each Cd atom of the trimetallic unit is chelated by an
additional ligand unit. The distorted coordination envi-
ronments around the Cd atoms in 8 are best described as
intermediate between square pyramidal [O(7) and O(8)
atoms of the same bridging ligand in apical positions
for Cd(1) and Cd(2) atoms, respectively] and trigonal
bipyramidal CdO5 cores [axial–axial bond angles O(1)–
Cd(1)–O(3) 172.8(2) and O(10)–Cd(2)–O(4) 167.3(2)ꢁ,
respectively]. Regardless of the nature of the imi-
dodiphosphinato ligand (chelate or bridging) the Cd–O
bond distances fall in a narrow range [2.163(4)–
The coordination core is completed by the oxygen
atom of an asymmetric bridging water molecule
˚
[Cd(1)–O(9) 2.787(5), Cd(2)–O(9) 2.459(5) A] with the
vectors of the Cd–Owater bonds placed trans to the non-
bridging oxygen atoms of the bridging ligands [O(9)–
Cd(1)–O(3) 156.7(1)ꢁ, O(9)–Cd(2)–O(5) 168.0(2)ꢁ]. This
results in distorted octahedral CdO6 cores for both Cd
atoms of the dinuclear 7ÆH2O (Table 3), sharing the
common face described by the O(4),O(6) and O(9)
atoms. The Cd–Oligand bond lengths [range 2.167(4)–
˚
˚
2.357(4) A] are similar to those observed for 4 (Table
2) or [Cd(acac)2]n [16].
2.270(3) A] and are similar to those observed in com-
pound 7ÆH2O (Table 3).
The two chelate six-membered CdO2P2N rings in
7ÆH2O exhibit different conformations, i.e., flattened
chair and distorted boat with Cd(1)/N(1) and O(7)/
P(8) atoms, respectively, in the apices. By contrast, the
The chelate CdO2P2N rings in 8 exhibit flattened boat
conformations, with O(2)/P(1) and Cd(2)/N(5) atoms,
respectively, in the apices. In contrast, the conforma-
tions of the three six-membered KO2P2N rings formed

M. Ghesner et al. / Inorganica Chimica Acta 358 (2005) 3724–3734
3733
by the bridging ligands differ. One of them is again of
boat conformation [K(1)/N(3) in the apices] while the
other two are of chair conformation, with K(1)/N(2)
and K(1)/N(4) atoms, respectively, in the apices (Table
4).
210038 (7ÆH2O) and 210039 (8), respectively. Copies
of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: +44 1223 336 033; e-mail: deposit@ccdc.
cam.ac.uk or www:http://www.ccdc.cam.ac.uk).
In all compounds investigated, regardless of the nat-
ure of the chalcogens attached to the phosphorus atoms
and the coordination pattern exhibited, there are some
common features within a ligand unit. Thus, the magni-
tudes of the interatomic distances (Tables 2 and 3) sug-
gest single phosphorus–sulfur and phosphorus–oxygen
bonds, while considerable double bond character should
be considered for the phosphorus–nitrogen bonds [cf.
(S@PMe2)2NH [17]: P@S 1.939(2)/1.962(2), P–N
Acknowledgements
This work was supported by the National University
Research Council of Romania (CNCSIS Grant, A-358/
80/2005). M.B.H. thanks the UK Engineering and Phys-
ical Sciences Council for support of the X-ray facilities
at Southampton. J.E.D. thanks the University of Wind-
sor for financial support.
˚
1.679(3)/1.9759(3) A; Me–S–PPh2@N–PPh2@S [31]: P–
S
1.562(2) A;
2.071(1), P@S 1.954(1), P–N 1.610(2), P@N
˚
(O@PPh2)(S@PPh2)2NH
[29]:
P@O
1.491(4), P@S 1.935(2), (S)P–N 1.694(4), (O)P–N
References
˚
1.668(5) A; Ph2P(@O)OH [32]: P@O 1.486(6), P–O
˚
1.526(6) A]. The differences in the bond angles within
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