Lanthanide nitrate complexes of diphenylmethylphosphine oxide: Synthesis and spectroscopic studies. Crystal structures of [La(Ph2MePO)3(NO3)3], [La(Ph2MePO)4 (NO3)3]·xMe2CO and [Yb(ph2MePO)4(NO3)2] PF6

Article abstract of DOI:10.1016/S0277-5387(01)00796-3

The reaction of Ln(NO₃)₃·6H₂O (Ln = lanthanide except Pm) with Ph₂MePO in a 1:3 or 1:4 ratio in acetone or ethanol produces [Ln(Ph₂MePO)₃(NO₃)₃] which have been characterised by analysis, IR, ¹H and ³¹P{¹H} NMR spectroscopy and conductance measurements. The [Ln′(Ph₂MePO)₃(NO₃)₃] (Ln′= Pr-Tb) exist only as tris complexes in solution and are unaffected by the presence of excess Ph₂MePO. In contrast the [Ln″(Ph₂MePO)₃(NO₃)₃] (Ln″ = Ho-Lu) partially decompose in CH₂Cl₂ solution into [Ln″(Ph₂MePO)₄ (NO₃)₂]⁺, and [Ln″(Ph₂MePO)₄ (NO₃)₂] PF₆ are readily isolated from Ln″(NO₃)₃, Ph₂MePO and NH₄PF₆ in acetone. For lanthanum only, a neutral 1:4 complex [La(Ph₂MePO)₄(NO₃)₃] was isolated. X-ray crystal structures show that [La(Ph₂MePO)₃(NO₃)₃] contains nine-coordinate La, whilst [La(Ph₂MePO)₄ (NO₃)₃]·xMe₂CO contains a ten-coordinate metal centre. The structure of [Yb(Ph₂MePO)₄ (NO₃)₂]PF₆ reveals an eight-coordinate cation and all complexes contain bidentate nitrato-groups.

Full text of DOI:10.1016/S0277-5387(01)00796-3

Polyhedron 20 (2001) 2055–2062
www.elsevier.com/locate/poly
Lanthanide nitrate complexes of diphenylmethylphosphine oxide:
synthesis and spectroscopic studies. Crystal structures of
[La(Ph2MePO)3(NO3)3], [La(Ph2MePO)4(NO3)3]·xMe2CO and
[Yb(Ph2MePO)4(NO3)2]PF6
Matthew Bosson, William Levason *, Tajesh Patel, Michael C. Popham,
Michael Webster
Department of Chemistry, Uni6ersity of Southampton, Southampton, SO17 1BJ, UK
Received 26 February 2001; accepted 29 March 2001
Abstract
The reaction of Ln(NO3)3·6H2O (Ln=lanthanide except Pm) with Ph2MePO in a 1:3 or 1:4 ratio in acetone or ethanol
produces [Ln(Ph2MePO)3(NO3)3] which have been characterised by analysis, IR, 1H and 31P{1H} NMR spectroscopy and
conductance measurements. The [Ln%(Ph2MePO)3(NO3)3] (Ln%=Pr–Tb) exist only as tris complexes in solution and are unaffected
by the presence of excess Ph2MePO. In contrast the [Ln¦(Ph2MePO)3(NO3)3] (Ln¦=Ho–Lu) partially decompose in CH2Cl2
solution into [Ln¦(Ph2MePO)4(NO3)2]+, and [Ln¦(Ph2MePO)4(NO3)2]PF6 are readily isolated from Ln¦(NO3)3, Ph2MePO and
NH4PF6 in acetone. For lanthanum only, a neutral 1:4 complex [La(Ph2MePO)4(NO3)3] was isolated. X-ray crystal structures
show that [La(Ph2MePO)3(NO3)3] contains nine-coordinate La, whilst [La(Ph2MePO)4(NO3)3]·xMe2CO contains a ten-coordinate
metal centre. The structure of [Yb(Ph2MePO)4(NO3)2]PF6 reveals an eight-coordinate cation and all complexes contain bidentate
nitrato-groups. © 2001 Elsevier Science Ltd. All rights reserved.
Keywords: Lanthanide; Phosphine oxide; X-ray structure
NO3)] form only with Ln%=La, Ce, Pr or Nd, whilst
1. Introduction
for
the
elements
Tb–Lu
eight-coordinate
[Ln(Ph3PO)4(h2-NO3)2]NO3 were isolated as solids. So-
lution speciation also varies with Ln. In related studies
with Sc and Y [3], the complexes characterised included
[Sc(Ph3PO)2(h2-NO3)3], [Y(Ph3PO)3(h2-NO3)3] and
[Y(Ph3PO)4(h2-NO3)2]NO3. Here we report the com-
plexes formed between Ln(NO3)3 and Ph2MePO, which
is expected to be a stronger donor and sterically less
demanding than Ph3PO. The synthesis and crystal
Phosphine oxides have proved popular ligands for
complexing with oxophilic metals like the lanthanides
and actinides, and they have been widely used in sol-
vent extraction and separation processes. The over-
whelming majority of complexes isolated with the
lanthanides have involved Ph3PO, with very limited
data on complexes of other R3PO ligands [1]. We have
recently reported [2] a detailed study of the reactions of
Ln(NO3)3 (Ln=lanthanide except Pm) with Ph3PO,
and found subtle variations with the lanthanide con-
cerned and the reaction conditions. Whilst nine-coordi-
nate [Ln(Ph3PO)3(h2-NO3)3] are known for all the
metals, nine-coordinate [Ln%(Ph3PO)4(h2-NO3)2(h1-
structures
of
[Sc(Ph2MePO)4(NO3)2]NO3
and
[Y(Ph2MePO)3(NO3)3] have been described [3].
2. Experimental
Lanthanide nitrates were obtained as before [2] and
Ph2MePO (Aldrich) was used as received. 31P{1H}
NMR spectra were recorded on a Bruker DPX400 at
* Corresponding author. Tel.: +44-2380-595000; fax: +44-2380-
593782.
E-mail address: wxl@soton.ac.uk (W. Levason).
0277-5387/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0277-5387(01)00796-3

2056
M. Bosson et al. / Polyhedron 20 (2001) 2055–2062
161.9 MHz and referenced to external 85% H3PO4.
Other physical measurements were carried out as de-
scribed previously [2,3].
2.1.5. [Sm(Ph2MePO)3(NO3)3]
White crystals. Yield: 59%. Anal. Found: C, 47.2; H,
4.0; N, 4.3. Calc. for C39H39N3O12P3Sm: C, 47.6; H,
4.0; N, 4.3%. IR (CsI, cm−1) 3057w, 3006w, 2918w,
1484br, 1460m, 1438m, 1292s, 1169s, 1147s, 1126m,
1097m, 1071m, 1031m, 996w, 894s, 883s, 817m, 782m,
2.1. Synthesis
1
746s, 716m, 697s, 510s, 447m. H NMR (CDCl3, 300
The complexes were prepared by similar methods,
representative examples of which are described. For
others only the physical data are noted.
K): l 5.5 (br), 6.7 (m), 7.1 (m). \M (10−3 mol dm−3
CH2Cl2) 3 V−1 cm2 mol−1
.
2.1.6. [Eu(Ph2MePO)3(NO3)3]
2.1.1. [La(Ph2MePO)3(NO3)3]
White powder. Yield: 50%. Anal. Found: C, 47.0; H,
4.1; N, 4.2. Calc. for C39H39EuN3O12P3: C, 47.5; H, 4.0;
N, 4.3%. IR (CsI, cm−1) 3031w, 2920w, 1497br, 1484s,
1438m, 1359s, 1302s, 1170m, 1148s, 1127m, 1099m,
1072w, 1033m, 996w, 895m, 885s, 818m, 783m, 746s,
A solution of La(NO3)3·6H2O (0.43 g, 1.0 mmol) in
acetone (10 cm3) was added to a solution of Ph2MePO
(0.54 g, 2.5 mmol) in acetone (10 cm3), and the mixture
heated to boiling. After concentration to 5 cm3 the
solution was refrigerated for 24 h. The white solid was
filtered off and dried in vacuo. Yield: 0.46 g (47%).
Anal. Found: C, 47.9; H, 4.0; N, 4.3. Calc. for
C39H39LaN3O12P3: C, 48.1; H, 4.0; N, 4.3%. IR (CsI,
cm−1) 3084w, 3005w, 1489br, 1474s, 1438m, 1361s,
1292s, 1165sh, 1144s, 1127m, 1097m, 1072m, 1029s,
998m, 895s, 854s, 819m, 782s, 732s, 718m, 698s, 503s,
1
694s, 508s, 450m. H NMR (CDCl3, 300 K): l 3.3 (br),
4.7–5.6 (br).
V
\
M
(10−3 mol dm−3 CH2Cl2)
5
−1 cm2 mol−1
.
2.1.7. [Gd(Ph2MePO)3(NO3)3]
White powder. Yield 48%. Anal. Found: C, 47.5; H,
3.8; N, 4.2. Calc. for C39H39GdN3O12P3: C, 47.2; H,
4.0; N, 4.2%. IR (CsI, cm−1) 3096w, 3058w, 2913w,
1487br, 1438m, 1357s, 1304m, 1172m, 1154s, 1125m,
1106m, 1077w, 1033m, 995w, 896m, 888s, 818m, 779m,
743s, 695s, 511s, 449m. \M (10−3 mol dm−3 CH2Cl2) 3
1
2
397s. H NMR (CDCl3, 300 K): l 1.95 (d, J=16 Hz),
7.3–7.8 (m).
(10−3 mol dm−3 CH2Cl2) 1.5
−1 cm2 mol−1
\
M
V
.
2.1.2. [Ce(Ph2MePO)3(NO3)3]
V
−1 cm2 mol−1
.
Colourless solid. Yield: 59%. Anal. Found: C, 48.0;
H, 3.7; N, 4.1. Calc. for C39H39CeN3O12P3: C, 48.1; H,
4.0; N, 4.3%. IR (CsI, cm−1) 3057w, 3005w, 2918w,
1594w, 1473br, 1438m, 1357s, 1340s, 1299s, 1165sh,
1149s, 1124s, 1096s, 1070m, 1029s, 997m, 895s, 888s,
2.1.8. [Tb(Ph2MePO)3(NO3)3]
White powder. Yield: 66%. Anal. Found: C, 47.0; H,
3.8; N, 4.5. Calc. for C39H39N3O12P3Tb: C, 47.2; H, 4.0;
N, 4.2%. IR (CsI, cm−1) 3053w, 3010w, 2918w, 1492br,
1438m, 1359s, 1304s, 1174m, 1149s, 1127m, 1099m,
1073w, 1035m, 999w, 896m, 884s, 818m, 784m, 746s,
717m, 697s, 511s, 450m. \M (10−3 mol dm−3 CH2Cl2)
1
820m, 782m, 748s, 717m, 695s, 511s, 445m. H NMR
2
(CDCl3, 300 K): l 4.1 (d, J=16 Hz), 7.5–7.8 (m), 8.7
(m). \M (10−3 mol dm−3 CH2Cl2) 1 V−1 cm2 mol−1
.
4 V−1 cm2 mol−1
.
2.1.3. [Pr(Ph2MePO)3(NO3)3]
Green powder. Yield: 49%. Anal. Found: C, 47.8; H,
3.3; N, 4.1. Calc. for C39H39N3O12P3Pr: C, 48.0; H, 4.0;
N, 4.3%. IR (CsI, cm−1) 3056w, 3006w, 2920w, 1484br,
1456s, 1438m, 1300s, 1284s, 1165m, 1142s, 1123m,
1090m, 1069m, 1028s, 994m, 892s, 880s, 817m, 780m,
2.1.9. [Dy(Ph2MePO)3(NO3)3]
White powder. Yield: 65%. Anal. Found: C, 46.1; H,
3.8; N, 4.4. Calc. for C39H39DyN3O12P3: C, 46.8; H, 3.9;
N, 4.2%. IR (CsI, cm−1) 3058w, 3006w, 2920w, 1475br,
1437m, 1318s, 1299s, 1171m, 1151s, 1123m, 1099m,
1071w, 1033m, 994w, 895m, 885s, 814m, 780m, 743s,
716m, 690s, 509s, 504s, 447w. \M (10−3 mol dm−3
1
742s, 715m, 695s, 509s, 438m. H NMR (CDCl3, 300
K): l 7.2 (br), 8.3 (br), 11.3 (br). \M (10−3 mol dm−3
CH2Cl2) 1 V−1 cm2 mol−1
.
CH2Cl2) 7 V−1 cm2 mol−1
.
2.1.4. [Nd(Ph2MePO)3(NO3)3]
2.1.10. [Ho(Ph2MePO)3(NO3)3]
Pale blue crystals. Yield: 50%. Anal. Found: C, 47.7;
H, 4.0; N, 4.1. Calc. for C39H39N3NdO12P3: C, 47.9; H,
4.0; N, 4.3%. IR (CsI, cm−1) 3058w, 3006w, 2916w,
1475br, 1437s, 1338m, 1289s, 1167m, 1142s, 1126m,
1090m, 1071w, 1023m, 994w, 896s, 880s, 818m, 781m,
Pink crystals. Yield: 43%. Anal. Found: C, 45.9; H,
4.2; N, 3.7. Calc. for C39H39HoN3O12P3: C, 46.8; H,
3.9; N, 4.2%. IR (CsI, cm−1) 3054w, 3007w, 2920w,
1474br, 1437m, 1325s, 1294s, 1175m, 1151s, 1123m,
1099m, 1071w, 1033m, 994w, 892s, 885s, 814m, 776m,
1
1
743s, 709m, 690s, 509s, 443m. H NMR (CDCl3, 300
747s, 714m, 695s, 504s, 448m. H NMR (CDCl3, 300
2
K): l 4.7 (d, J=15 Hz), 7.9 (m), 9.4 (m). \M (10−3
K): l 3.5 (br), 11.2–12.5 (m). \M (10−3 mol dm−3
mol dm−3 CH2Cl2) 1 V−1 cm2 mol−1
.
CH2Cl2) 11 V−1 cm2 mol−1
.

M. Bosson et al. / Polyhedron 20 (2001) 2055–2062
2057
1
2.1.11. [Er(Ph2MePO)3(NO3)3]
510s. H NMR (CDCl3, 300 K): l 15.4 (br), 10.6–10.1,
Pink crystals. Yield: 44%. Anal. Found: C, 46.8; H,
4.3; N, 3.8. Calc. for C39H39ErN3O12P3: C, 46.7; H, 3.9;
N, 4.2%. IR (CsI, cm−1) 3058w, 3006w, 1480s, 1438m,
1304s, 1294s, 1171s, 1147s, 1127m, 1099m, 1066w,
1033m, 994w, 895m, 885s, 814m, 776m, 743s, 714m,
695s, 512s, 505s, 443m. 1H NMR (CDCl3, 300 K): l 2.4
(d) 7.4 (m), 7.9 (m). \M (10−3 mol dm−3 CH2Cl2) 10
7.4. \M (10−3 mol dm−3 CH2Cl2) 23 V−1 cm2 mol−1
.
2.1.16. [Er(Ph2MePO)4(NO3)2]PF6
Pink crystals. Yield: 48%. Anal. Found: C, 47.6; H,
4.3; N, 2.2. Calc. for C52H52ErF6N2O10P5: C, 48.1; H,
4.0; N, 2.2%. IR (CsI, cm−1) 3058w, 3006w, 1506s,
1440m, 1358s, 1298s, 1188sh, 1153vs, 1127m, 1102m,
1074w, 1033m, 999w, 897m, 839vs, 779m, 755s, 746s,
V
−1 cm2 mol−1
.
1
719m, 696s, 559s, 510s, 443m. H NMR (CDCl3, 300
2.1.12. [Tm(Ph2MePO)3(NO3)3]
K): l 4.5–5.5, 6.5–7.2. \M (10−3 mol dm−3 CH2Cl2)
White powder. Yield: 45%. Anal. Found: C, 46.7; H,
3.9; N, 3.7. Calc. for C39H39N3O12P3Tm: C, 46.7; H,
3.9; N, 4.2%. IR (CsI, cm−1) 3067w, 2963w, 1484br,
1438m, 1384s, 1304s, 1185s, 1150s, 1126m, 1098m,
1034m, 996w, 894m, 880s, 815m, 802m, 746s, 735m,
690s, 514s, 499s, 450m. 1H NMR (CDCl3, 300 K): l 3.4
(d), 7.2 (br,m). \M (10−3 mol dm−3 CH2Cl2) 11
22 V−1 cm2 mol−1
.
2.1.17. [Tm(Ph2MePO)4(NO3)2]PF6
White powder. Yield: 55%. Anal. Found: C, 47.7; H,
4.3; N, 2.0. Calc. for C52H52F6N2O10P5Tm: C, 47.9; H,
4.0; N, 2.2%. IR (CsI, cm−1) 3067w, 2963w, 1505br,
1440m, 1362s, 1298s, 1185sh, 1153vs, 1127m, 1110m,
1074w, 1034m, 999w, 897m, 839vs, 780m, 777s, 719m,
V
−1 cm2 mol−1
.
1
697s, 559s, 510s. H NMR (CDCl3, 300 K): l 2.5 (br)
2.1.13. [Yb(Ph2MePO)3(NO3)3]
4.0–4.8.
\
M
(10−3
mol dm−3
CH2Cl2)
25
White powder. Yield: 63%. Anal. Found: C, 46.7; H,
3.9; N, 4.2. Calc. for C39H39N3O12P3Yb: C, 46.5; H, 3.9;
N, 4.2%. IR (CsI, cm−1) 3057w, 3013w, 1471br, 1342s,
1309s, 1161br, 1127m, 1098m, 1068w, 1030m, 994w,
886m, 875s, 816m, 781m, 749s, 716m, 698s, 512s, 503s,
V
−1 cm2 mol−1
.
2.1.18. [Yb(Ph2MePO)4(NO3)2]PF6
White powder. Yield: 60%. Anal. Found: C, 48.3; H,
4.4; N, 2.3. Calc. for C52H52F6N2O10P5Yb: C, 47.8; H,
4.0; N, 2.1%. IR (CsI, cm−1) 3057w, 3013w, 1484br,
1440m, 1357s, 1299s, 1154vs, 1127m, 1100m, 1074w,
1034m, 999w, 887m, 839vs, 782m, 749s, 719m, 679s,
1
440w. H NMR (CDCl3, 300 K): l 4.3–6.0 (br). \M
(10−3 mol dm−3 CH2Cl2) 13 V−1 cm2 mol−1
.
1
2.1.14. [Lu(Ph2MePO)3(NO3)3]
559m, 510s, 474m. H NMR (CDCl3, 300 K): l 3.0–
White powder. Yield: 55%. Anal. Found: C, 46.3; H,
3.8; N, 4.2. Calc. for C39H39LuN3O12P3: C, 46.4; H, 3.9;
N, 4.2%. IR (CsI, cm−1) 3062w, 2963w, 1478m, 1439m,
1325s, 1262m, 1165s, 1150s, 1126m, 1100s, 1032m,
891m, 876w, 815m, 802m, 781w, 749s, 717m, 690s,
3.5, 5.8–6.4.
\
(10−3 mol dm−3 CH2Cl2) 24
M
V
−1 cm2 mol−1
.
2.1.19. [Lu(Ph2MePO)4(NO3)2]PF6
White powder. Yield: 65%. Anal. Found: C, 48.2; H,
4.4; N, 2.4. Calc. for C52H52F6LuN2O10P5: C, 47.7; H,
4.0; N, 2.1%. IR (CsI, cm−1) 3062w, 2963w, 1482br,
1440m, 1365s, 1300s, 1155vs, 1127m, 1110m, 1074w,
1035m, 999w, 888m, 839vs, 783m, 749s, 719m, 697s,
1
2
500s, 392m. H NMR (CDCl3, 300 K): l 1.9 (d, J=16
Hz), 7.3–7.6 (m). \M (10−3 mol dm−3 CH2Cl2) 12
V
−1 cm2 mol−1
.
1
2.1.15. [Ho(Ph2MePO)4(NO3)2]PF6
559s, 514s, 475m. H NMR (CDCl3, 300 K): l 1.75 (d,
Ammonium hexafluorophosphate (0.08 g, 0.5 mmol)
and holmium nitrate hydrate (0.22 g, 0.5 mmol) were
dissolved separately in acetone (5 cm3) and the solu-
tions mixed and stirred for 5 min. The solution was
filtered and a solution of Ph2MePO (0.55 g, 2.5 mmol)
in acetone (15 cm3) added, and the mixture boiled. The
solution was cooled, concentrated in vacuo until it
became cloudy and refrigerated for 48 h. The pink
crystals produced were filtered off, rinsed with diethyl
ether (10 cm3) and dried in vacuo. The solid was
recrystallised from CH2Cl2. Yield: 0.55 g (43%). Anal.
Found: C, 48.1; H, 4.3; N, 2.2. Calc. for
C52H52F6HoN2O10P5: C, 48.1; H, 4.0; N, 2.2%. IR (CsI,
cm−1) 3054w, 3007w, 1511s, 1485m, 1441m, 1362m,
1294m, 1186sh, 1152vs, 1129m, 1110w, 1076w, 1033m,
999m, 898m, 839vs, 779s, 754s, 747s, 717m, 696s, 559s,
2J=16 Hz), 7.3–7.6 (m). \M (10−3 mol dm−3 CH2Cl2)
24 V−1 cm2 mol−1
.
2.1.20. [La(Ph2MePO)4(NO3)3]
Ph2MePO (0.11 g, 0.50 mmol) was added to a solu-
tion of [La(Ph2MePO)3(NO3)3] (0.098 g, 0.10 mmol) in
CH2Cl2 (20 cm3) and the mixture heated to reflux, then
cooled. A 31P{1H} NMR spectrum of this solution at
−80°C showed the tetrakis complex and free ligand as
the only major species. The solvent was removed in
vacuo, and the product dried, and then ground to a fine
powder. The white powder was stirred with diethyl
ether (50 cm3) for 48 h, the residual solid filtered off
and dried in vacuo. Yield: 0.11 g (90%). Anal. Found:
C, 52.0; H, 3.4; N, 4.0. Calc. for C52H52LaN3O13P4: C,
52.5; H, 3.5; N, 4.4%. IR (CsI, cm−1) 3066w, 3005w,

2058
M. Bosson et al. / Polyhedron 20 (2001) 2055–2062
Table 1
Crystallographic data a
Compound
Empirical formula
Mr
[La(Ph2MePO)3(NO3)3]
C39H39LaN3O12P3
973.55
[La(Ph2MePO)4(NO3)3]·xMe2CO
C52H52LaN3O13P4+xC3H6O
1247.83 (x=1)
[Yb(Ph2MePO)4(NO3)2]PF6
C52H52F6N2O10P5Yb
1306.85
Crystal system
Space group
Unit cell dimensions
triclinic
monoclinic
C2/c (no. 15)
triclinic
(
(
P1 (no. 2)
P1 (no. 2)
,
a (A)
10.1697(2)
10.2766(2)
21.6636(3)
98.879(1)
99.412(1)
103.229(1)
2130.52(7)
1.518
22.896(3)
25.231(4)
12.784(4)
90.0
119.97(1)
90.0
13.1163(2)
14.9535(2)
15.7817(2)
103.064(1)
101.265(1)
106.621(1)
2774.9(1)
1.564
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
6397(2)
1.296
Dcalc (g cm−3
)
Z
2
4
2
Total number of observations
Number of unique observations
Absorption correction
24884
9398 (Rint=0.0604)
sortav
9398
524/0
5792
37259
9661 (Rint=0.096)
sortav
9661
623/18
5646 (Rint=0.0397)
psi-scan
5646
272/0
8.27
Number of data in refinement
Number of parameters/restraints
v (cm−1
)
11.78
19.07
S
1.04
1.14
0.96
R (Fo\2|(Fo))
wR2 (all data)
0.0393 (7817 refls)
0.0915
0.0962 (4675 refls)
0.2785
0.0552 (8714 refls)
0.1598
1/2
ꢃ
n
a
In common, T=150 K, u (Mo Ka)=0.71073 A. R=ꢀꢁFoꢂ−ꢂFcꢁ/ꢀꢂFoꢂ; wR2= ꢀw(F2o−Fc2)2/ꢀwFo4
.
,
1484br, 1474s, 1438m, 1360s, 1288s, 1166sh, 1143s,
1127m, 1097m, 1072m, 1030s, 998m, 895s, 819m, 783s,
747s, 718m, 697s, 512s, 397s. 1H NMR (CDCl3, 300 K):
for the solution. The trial solution came from SHELXS-
86 (TREF) [5] with La(1), N(2) and O(6) located on a
twofold axis. Refinement as in Section 2.2.1 [6] with
geometrically fixed rings (AFIX 66), disorder in one
phenyl ring with two images observed in the electron-
density map and a partially modelled, disordered ace-
tone solvate molecule. No H atoms were included in the
model (see Table 1).
2
l 1.95 (d, J=16 Hz), 7.3−7.8 (m).
2.2. Crystal structure determinations
2.2.1. [La(Ph2MePO)3(NO3)3]
Very thin small platy crystals were obtained from the
NMR sample in CH2Cl2 by slow evaporation over
several weeks. Data were collected on a Nonius CCD
diffractometer at 150 K and corrected for absorption
using the SORTAV procedure [4]. The default PATT
and TREF calculations in SHELXS-86 [5] failed to give a
solution and the La position was obtained by hand
calculation from the Patterson map. Repeated structure
factor and electron density calculations revealed the
remaining non-H atoms. At a later stage most of the H
atoms appeared and were added to the model in calcu-
lated positions. Full-matrix least-squares refinement on
F2 [6] converged to the final solution (see Table 1).
2.2.3. [Yb(Ph2MePO)4(NO3)2]PF6
Crystals were obtained by vapour diffusion of Et2O
into a CH2Cl2 solution on the compound with the
sealed container held in the refrigerator. Data were
collected as in Section 2.2.1 and corrected for absorp-
tion using the SORTAV procedure [4]. Structural solu-
tion and refinement are as given in Section 2.2.2. The
PF6 anion was disordered and although six F atoms
were identified there were a number of potential F atom
peaks in the electron-density map that were not mod-
elled. Restraints (DFIX) were used on PꢀF and F···F
distances and in the final cycle the PF6 group was kept
fixed. There was also evidence of disorder in one of the
phenyl groups on P(4).
2.2.2. [La(Ph2MePO)4(NO3)3]·xMe2CO
Repeated attempts to grow suitable crystals failed,
but a few modest quality needle crystals were obtained
directly from one synthesis with very dilute solutions
over several weeks and used to collect data at 150 K on
a Rigaku AFC7S diffractometer. The diffraction peaks
were broad, and the systematic absences gave the space
group as Cc or C2/c of which the latter was finally used
3. Results and discussion
3.1. [Ln(Ph2MePO)3(NO3)3]
The reaction of Ln(NO3)3·6H2O with Ph2MePO in a
1:2–1:4 molar ratio in hot acetone produced good

M. Bosson et al. / Polyhedron 20 (2001) 2055–2062
2059
yields of [Ln(Ph2MePO)3(NO3)3], which in contrast to
[Ln(Ph3PO)3(NO3)3]·2Me2CO are not solvated. The X-
ray structure of [La(Ph2MePO)3(NO3)3] shows a nine-
coordinate lanthanum centre coordinated to three
phosphine oxides and three bidentate nitrate groups
(below), and the very similar IR spectra indicate this
structure is present in the other complexes. IR spectra
were obtained in both Nujol mulls and in CsI discs,
generally the CsI disc spectra were better resolved and
the data quoted in the Section 2 refers to the latter.1
Very strong features 1165–1140 cm−1 are associated
with w(PO) (compare 1172 cm−1 in the ‘free’ ligand)
and features at approximately 1475, 1325, 1030 and 815
cm−1 are attributable to the bidentate nitrate groups.
The structure of [La(Ph2MePO)3(NO3)3] reveals a nine-
coordinate La centre (Fig. 1, Table 2) with coordina-
tion from three phosphine oxide ligands and three
symmetrically bonded bidentate nitrate groups. The
three (P)OꢀLaꢀO(P) angles (ca. 86°) shows that this
complex may be described as fac-octahedral where the
nitrate ligands have been replaced conceptually by
monoatomic species. The nitrate groups are symmetri-
cally bonded and show clearly the changes in geometry
(bond lengths and angles) noted before [3]. The
triphenylphosphine oxide analogue [La(Ph3PO)3(NO3)3]
has been reported [7] as the mer isomer but the
,
LaꢀO(P) (2.373–2.427) and LaꢀO(N) (2.583–2.681 A)
are similar to the present compound.
As observed for Ph3PO complexes [2], the solution
behaviour varies along the Ln series, although that with
Ph2MePO differs in detail from that previously ob-
served with Ph3PO. The complexes [Ln%(Ph2MePO)3-
(NO3)3] (Ln%=Pr, Nd, Sm, Eu, Gd and Tb) are non-
Fig. 1. Structure of [La(Ph2MePO)3(NO3)3] showing the atom num-
bering scheme. H atoms have been omitted for clarity and thermal
ellipsoids are drawn at the 50% probability level.
conductors in 10−3 mol dm−1 CH2Cl2 and the con-
2
ductances do not increase upon addition of a fivefold
molar excess of Ph2MePO. The La and Ce complexes
behave differently and are discussed in Section 3.2. The
complexes [Ln¦(Ph2MePO)3(NO3)3] (Ln¦=Dy, Ho, Er,
Tm, Yb or Lu) have small but significant conductances
although mostly less than half those expected for 1:1
electrolytes, and these conductances increase upon ad-
dition of excess Ph2MePO. We were unable to observe
31P NMR spectra for the Gd or Tb complexes no doubt
due to extreme line broadening. Solutions of the com-
plexes [Ln¦(Ph2MePO)3(NO3)3] (Ln¦=Ho, Er, Tm, Yb
or Lu) showed two 31P{1H} NMR resonances usually
(Table 3) one significantly broader than the other.
Addition of Ph2MePO to these solutions produced (in
addition to a free ligand resonance) a diminution in the
broader resonance and an increased intensity in the
sharper one. From our previous studies of
[Ln%(Ph3PO)3(NO3)3] [2], these data are readily inter-
preted as due to a mixture of [Ln%(Ph2MePO)3(NO3)3]
(broader resonance) and [Ln%(Ph2MePO)4(NO3)2]+
Table 2
,
Selected bond lengths (A) and angles (°) for [La(Ph2MePO)3(NO3)3]
Bond lengths
La(1)ꢀO(1)
La(1)ꢀO(2)
La(1)ꢀO(3)
La(1)ꢀO(5)
La(1)ꢀO(6)
P(1)ꢀO(1)
P(2)ꢀO(2)
P(3)ꢀO(3)
P(2)ꢀC(14)
P(2)ꢀC(15)
P(2)ꢀC(21)
N(1)ꢀO(4)
2.418(2)
2.407(2)
2.436(2)
2.634(2)
2.629(2)
1.507(2)
1.503(2)
1.505(2)
1.785(3)
1.794(3)
1.798(3)
1.223(3)
La(1)ꢀO(8)
La(1)ꢀO(9)
La(1)ꢀO(11)
La(1)ꢀO(12)
2.584(2)
2.641(2)
2.630(2)
2.589(2)
P(1)ꢀC(1)
P(1)ꢀC(2)
P(1)ꢀC(8)
P(3)ꢀC(27)
P(3)ꢀC(28)
P(3)ꢀC(34)
1.779(3)
1.795(3)
1.800(3)
1.778(3)
1.795(3)
1.797(3)
1.273(3),
1.263(3)
1.279(3),
1.256(3)
1.261(3),
1.281(3)
a
N(1)ꢀOc
N(2)ꢀO(7)
1.227(3)
1.217(3)
N(2)ꢀOc
N(3)ꢀOc
N(3)ꢀO(10)
Bond angles
O(1)ꢀLa(1)ꢀO(2)
O(1)ꢀLa(1)ꢀO(3)
O(2)ꢀLa(1)ꢀO(3)
La(1)ꢀO(1)ꢀP(1)
La(1)ꢀO(3)ꢀP(3)
OꢀPꢀC
82.03(7) O(5)ꢀLa(1)ꢀO(6)
85.60(7) O(8)ꢀLa(1)ꢀO(9)
88.84(7) O(11)ꢀLa(1)ꢀO(12)
144.8(1) La(1)ꢀO(2)ꢀP(2)
147.0(1)
48.50(6)
48.84(6)
48.96(6)
165.1(1)
1 In some cases KBr disc spectra showed weak features due to the
presence of ionic nitrate ions, which appear to arise from reaction
during the die pressing, particularly if the KBr is not thoroughly dry.
These problems were not experienced using dry CsI.
110.0(1)–
113.2(1)
CꢀPꢀC
106.3(1)–
108.9(1)
2 Although CH2Cl2 is not commonly used for conductivity mea-
surements it was used here so that correlation could be made with the
NMR data obtained from chlorocarbon solutions.
a Oc are coordinated O atoms of the nitrate ligand.

2060
M. Bosson et al. / Polyhedron 20 (2001) 2055–2062
Table 3
3.2. [La(Ph2MePO)4(NO3)3]
31P{1H} NMR spectra a
The 31P{1H} NMR spectrum of [La(Ph2MePO)3-
(NO3)3] in CH2Cl2 solution at ambient temperatures is
a sharp line at l 39.2 (Table 3), and on addition of
Ph2MePO (l 29.0) an averaged signal is observed con-
sistent with fast intramolecular exchange. Cooling the
solution slows the exchange and at 195 K two reso-
nances are present at l 39.7 (tris) and 38.1 and the
latter increases in relative intensity with more added
Ph2MePO. The second resonance is assigned to
[La(Ph2MePO)4(NO3)3] and notably the solution shows
no significant increase in conductance at this stage.
Many attempts to crystallise [La(Ph2MePO)4(NO3)3]
from these solutions resulted in isolation of only
[La(Ph2MePO)3(NO3)3]. Serendipitously, from one such
attempt using a very dilute acetone solution a very
small number of crystals formed over about six weeks
and one was submitted to X-ray crystallographic study.
Although a poor quality crystal, the structure is clearly
established as [La(Ph2MePO)4(h2-NO3)3] with ten-coor-
dinate La (Fig. 2, Table 4). The structure is molecular
and has crystallographic twofold symmetry with La(1),
N(2) and O(6) positioned on the C2 axis. Although the
data are not of good quality, the LaꢀO(P) distances
(Table 4) are longer than in [La(Ph2MePO)3(NO3)3]
(Table 2). The corresponding triphenylphosphine oxide
complex [La(Ph3PO)4(NO3)3] is again molecular but has
a nine-coordinate La due to the presence of one
monodentate h1-NO3 ligand [2]. A bulk (powdered)
sample of [La(Ph2MePO)4(h2-NO3)3] was eventually
obtained by rapidly evaporating to dryness a mixture of
[La(Ph2MePO)3(NO3)3] and excess Ph2MePO in CH2Cl2
(shown by low temperature 31P{1H} NMR spec-
troscopy to be predominently the tetrakis complex),
and removing the excess Ph2MePO by prolonged ex-
traction with diethyl ether. The IR spectrum has only
small differences to that of [La(Ph2MePO)3(h2-NO3)3],
whilst the 31P{1H} NMR spectrum at 195 K shows, as
expected, almost complete decomposition into the
tris(complex) and Ph2MePO. On further addition of
Ph2MePO to the ‘[La(Ph2MePO)4(NO3)3]’ in CH2Cl2,
the resonance at 39.7 diminishes further, a new reso-
nance at 36.8 appears, and the solution now shows a
significant conductance which we tentatively suggest is
due to [La(Ph2MePO)5(NO3)2]+. At very high
Ph2MePO:La ratios (\15:1) the 31P{1H} NMR spec-
trum at 195 K contains the l 36.8 resonance and free
ligand as the major features, and has a molar conduc-
tance of approximately 20 V−1 mol−1 cm2 typical of a
1:1 electrolyte. However all attempts to isolate this
complex as a solid have failed. A large excess (\15:1
molar ratio) of Ph2MePO added to [Ce(Ph2MePO)3-
(NO3)3] solution also produces a significant conduc-
tance (limiting value ca. 10 V−1 cm2 mol−1). Studies of
the cerium system are complicated by the effects of
paramagnetism (f1) where the 31P{1H} NMR resonance
Compound
l (295 K)
[La(Ph2MePO)3(NO3)3]
[Ce(Ph2MePO)3(NO3)3]
[Pr(Ph2MePO)3(NO3)3]
[Nd(Ph2MePO)3(NO3)3]
[Sm(Ph2MePO)3(NO3)3]
[Eu(Ph2MePO)3(NO3)3]
[Gd(Ph2MePO)3(NO3)3]
[Tb(Ph2MePO)3(NO3)3]
[Dy(Ph2MePO)3(NO3)3]
[Ho(Ph2MePO)3(NO3)3]
[Er(Ph2MePO)3(NO3)3]
[Tm(Ph2MePO)3(NO3)3]
[Yb(Ph2MePO)3(NO3)3]
[Lu(Ph2MePO)3(NO3)3]
[Ho(Ph2MePO)4(NO3)2]PF6
[Er(Ph2MePO)4(NO3)2]PF6
[Tm(Ph2MePO)4(NO3)2]PF6
[Yb(Ph2MePO)4(NO3)2]PF6
[Lu(Ph2MePO)4(NO3)2]PF6
39.2(25)
79(190) b
138(250) b
133(500) b
38.5(40)
−95(150)
not observed
not observed
−166(2000)
−65(1200), −97(275) c
−120(600) c, −165(1000)
−72(200) c, −135(1500)
14.5(220) c, −19.5(380)
42.1(30) c, 40.3(35)
−98(250), −145(quintet) d
−120(500), −145(quintet) d
−72(200), −145(quintet) d
14.5(190), −145(quintet) d
42.1(30), −145(quintet) d
a In CH2Cl2-10%CDCl3; approximate line-widths at half-height in
parentheses.
b At 273 K.
c Resonance assigned to [Ln(Ph2MePO)4(NO3)2]+ cation.
d [PF6]− anion.
Fig. 2. Structure of the La residue in [La(Ph2MePO)4(NO3)3]·
xMe2CO showing the atom numbering scheme. Thermal ellipsoids
are drawn at the 40% probability level. The molecule has crystallo-
graphic twofold symmetry.
(sharper resonance), which also correlates with the con-
ductance data. Although [Dy(Ph2MePO)3(NO3)3] shows
a small conductance, only one very broad 31P{1H}
resonance was observed; if two species are present
either the resonances are within the same broad envel-
ope or one resonance is too broad to observe.

M. Bosson et al. / Polyhedron 20 (2001) 2055–2062
2061
is both contact shifted and broadened, and both effects
vary markedly with temperature [8]. At 300 K fast
exchange occurs with added Ph2MePO, but on cooling
to 220 K, the exchange is slow and the resonance of
[Ce(Ph2MePO)3(NO3)3] is found at l 115 (W1/2=1500
Hz). A large excess of added ligand produces a new
sharper resonance l 92 (W1/2=800 Hz) which we tenta-
tively attribute to [Ce(Ph2MePO)x(NO3)2]+, although
the reaction does not go to completion. Similar effects
were not observed for Pr, Nd, Sm or Eu for which only
a single broad (contact shifted) 31P resonance was ob-
served, and this was unaffected by added ligand, ex-
change being slow even at near ambient temperatures.
(NO3)3] described in Section 3.1 show two species in
solution, the species producing the sharper resonance in
each system is proposed as [Ln%(Ph2MePO)4(NO3)2]+.
However, in contrast to the Ln%(NO3)3–Ph3PO systems,
where the [Ln%(Ph3PO)4(NO3)2]NO3 are readily isolated
from ethanol solutions of 1:6 Ln%(NO3)3–Ph3PO molar
ratio [2], in the present case attempts to crystallise or
precipitate solids from such solutions only produced
[Ln%(Ph2MePO)3(NO3)3], confirmed by a combination
of IR spectroscopy and analysis. The [Y(Ph2MePO)4-
(NO3)2]NO3 (Y is of similar radius to the later lan-
thanides) behaves similarly [3]. Rather than attempt to
find a solvent and Ln%–Ph2MePO ratio from which the
tetrakis complexes could be isolated, we adopted an
alternative approach. This involved the reaction of
Ln%(NO3)3, NH4PF6 and Ph2MePO in acetone in a 1:1:5
molar ratio, which deposited [Ln%(Ph2MePO)4(NO3)2]-
PF6 (Ln%=Ho–Lu) on concentration, and these were
recrystallised without decomposition from CH2Cl2. The
IR spectra of these complexes show single broad w(PO)
approximately 1150 cm−1 and strong PF−6 vibrations
at 840 and 560 cm−1 [9]. The 10−3 mol dm−3 solutions
in CH2Cl2 are 1:1 electrolytes and the 31P{1H} NMR
spectra show the characteristic septet of [PF6]− at l
−145, and a second broader resonance attributable to
[Ln%(Ph2MePO)4(NO3)2]+ (Table 3). The crystal struc-
ture of [Yb(Ph2MePO)4(NO3)2]PF6 showed an eight-co-
ordinate Yb with approximately a planar YbO4 group
formed by the phosphine oxide ligands with bidentate
nitrates above and below this plane (Fig. 3, Table 4).
On our previous formalism this is a trans-octahedral
geometry. The two nitrate groups are approximately
perpendicular to each other.
3.3. [Ln%(Ph2MePO)4(NO3)2]PF6 (Ln%=Ho–Lu)
The 31P{1H} NMR studies of [Ln%(Ph2MePO)3-
Table 4
,
Selected bond lengths (A) and angles (°) for [La(Ph2MePO)4-
(NO3)3]·xMe2CO and [Yb(Ph2MePO)4(NO3)2]PF6
[La(Ph2MePO)4(NO3)3]·xMe2CO
Bond lengths
La(1)ꢀO(1)
La(1)ꢀO(2)
La(1)ꢀO(4)
La(1)ꢀO(5)
PꢀC
2.462(7)
2.513(7)
2.649(8)
2.708(8)
1.74(1)–
1.89(1)
La(1)ꢀO(7)
P(1)ꢀO(1)
P(2)ꢀO(2)
2.650(7)
1.480(8)
1.502(7)
NꢀO
1.23(1)–
1.26(1)
Bond angles
a
O(1)ꢀLa(1)ꢀO(2)
O(1)ꢀLa(1)ꢀO(4)
O(4)ꢀLa(1)ꢀO(5)
La(1)ꢀO(1)ꢀP(1)
OꢀPꢀC
74.9(2) O(1)ꢀLa(1)ꢀO(1%)
73.9(3) O(2)ꢀLa(1)ꢀO(4)
73.2(4)
70.6(2)
47.9(3)
46.8(2) O(7)ꢀLa(1)ꢀO(7%) a
154.9(5) La(1)ꢀO(2)ꢀP(2)
149.3(4)
94.6(8)–
117.4(8)
108.2(6)–
114.4(6)
CꢀPꢀC
[Yb(Ph2MePO)4(NO3)2]PF6
Bond lengths
Yb(1)ꢀO(1)
Yb(1)ꢀO(2)
Yb(1)ꢀO(3)
Yb(1)ꢀO(4)
P(n)ꢀO(n)
2.221(4)
2.186(5)
2.193(4)
2.222(4)
1.490(5)–
1.508(5)
1.221(8),
1.221(9)
Yb(1)ꢀO(6)
Yb(1)ꢀO(7)
Yb(1)ꢀO(9)
Yb(1)ꢀO(10)
PꢀC
2.421(5)
2.452(5)
2.423(5)
2.410(5)
1.792(7)–
1.809(9)
1.256(8)–
1.280(7)
b
b
NꢀOt
NꢀOc
Bond angles
O(1)ꢀYb(1)ꢀO(2)
O(1)ꢀYb(1)ꢀO(3)
O(1)ꢀYb(1)ꢀO(4)
O(6)ꢀYb(1)ꢀO(7)
Yb(1)ꢀO(1)ꢀP(1)
Yb(1)ꢀO(2)ꢀP(2)
OꢀPꢀC
155.9(2) O(2)ꢀYb(1)ꢀO(3)
89.9(2) O(2)ꢀYb(1)ꢀO(4)
91.9(2) O(3)ꢀYb(1)ꢀO(4)
52.5(2) O(9)ꢀYb(1)ꢀO(10)
159.1(3) Yb(1)ꢀO(3)ꢀP(3)
167.6(4) Yb(1)ꢀO(4)ꢀP(4)
96.0(2)
92.4(2)
154.9(2)
52.6(2)
161.4(3)
150.0(3)
108.6(3)–
113.7(3)
116.5(5) O(9)ꢀN(2)ꢀO(10)
CꢀPꢀC
106.3(3)–
111.0(3)
115.9(6)
O(6)ꢀN(1)ꢀO(7)
a Symmetry operation: prime (%) −x, y, 1/2−z.
Fig. 3. Structure of the cation in [Yb(Ph2MePO)4(NO3)2]PF6 showing
the atom numbering scheme. Thermal ellipsoids are drawn at the 40%
probability level.
b Ot and Oc are terminal and coordinated O atoms of the nitrate
ligand, respectively.

2062
M. Bosson et al. / Polyhedron 20 (2001) 2055–2062
4. Conclusions
Data Centre, CCDC Nos. 158449, 158448, and 158450
for compounds ([La(Ph2MePO)3(NO3)3]), ([La(Ph2-
MePO)4(NO3)3]·xMe2CO), and (Yb), respectively.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: +44-1223-336033;
The results combined with our previous study of
Ph3PO complexes [2] show the subtle variations along
the lanthanide series. Whilst nine-coordination is fa-
voured early in the lanthanide series (as in [Ln(R3PO)3-
(NO3)3]) and nine or eight (as in [Ln(R3PO)4(NO3)2]+)
coordination later which correlates with the reducing
Ln3+ radius along the series, the fine detail is less easily
rationalised. For example the formation of eight-coor-
dinate Ln as [Ln(R3PO)4(h2-NO3)2]+ rather than
[Ln(R3PO)2(h2-NO3)3] shows a preference for R3PO
over NO3 later in the series, whereas for La itself, the
solid [La(R3PO)4(NO3)3] lose one R3PO in solution.
Our assumption that Ph2MePO should be a better
donor than Ph3PO (based upon the usual inductive
effects between Me and Ph) may be supported by the
somewhat shorter LaꢀO(P) distances in the Ph2MePO
complexes compared with those of Ph3PO. However the
proposal that Ph2MePO is sterically less demanding is
uncertain in practice, since the LnꢀOꢀP angles are
highly variable ranging from approximately 145–170°.
It should also be remembered that the solid and solu-
tion speciation may be different, several cases are de-
scribed above where the major solution form is not the
form which separates as a solid, obviously a conse-
quence of solubility differences and fast equilibria inter-
converting the forms in solution.
e-mail:
deposit@ccdc.cam.ac.uk
or
www:http://
www.ccdc.cam.ac.uk).
Acknowledgements
We thank Professor M.B. Hursthouse for the X-ray
data collection on the Nonius Kappa CCD diffrac-
tometer, and the EPSRC for support.
References
[1] T.S. Lobana, in: F.R. Hartley (Ed.), The Chemistry of
Organophosphorus Compounds, vol. 2, Wiley, New York, 1992,
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[2] W. Levason, E.H. Newman, M. Webster, Polyhedron 19 (2000)
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[3] L. Deakin, W. Levason, M.C. Popham, G. Reid, M. Webster, J.
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[4] R.H. Blessing, Acta Crystallogr., Sect. A 51 (1995) 33.
[5] G.M. Sheldrick, SHELXS-86, Program for the Solution of Crystal
Structures, University of Go¨ttingen, 1985.
[6] G.M. Sheldrick, SHELXL-97, Program for the Refinement of Crys-
tal Structures, University of Go¨ttingen, 1997.
[7] C. Huang, R. Xu, Y. Zhou, G. Xu, F. Guo, N. Zhu, Acta
Phys.-Chim. Sin. 3 (1987) 491 (Chem. Abs. 108 (1988) 123246r).
[8] G.N. LaMar, W.D. Horrocks Jr., R.H. Holm (Eds.), NMR of
Paramagnetic Molecules, Academic Press, NY, 1973 (chaps 12
and 13).
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
[9] G.M. Begun, A.C. Rutenberg, Inorg. Chem. 6 (1967) 2213.
.