Phosphine oxides complexes of neodymium(III) nitrate

INORG. NUCL. CHEM. LETTERS Vol.14, pp. 419-427 ©Pergamon Press Ltd. 1978. Printed in Great Britain

PnOSPHINE

A.M.G.

Mass abni

OXIDES

, M.L.R.

COMPLEXES

Gibran

OO20-1650/78/1101-O419 $02.00/0

OF

NEODYMIUM(III)

NITRATE

and O.A. S e r r a

* £ n s t i t u t o de Q u l m i c a da U n i v e r s i d a d e de Sao Paulo,

CP 20780, Sao Paulo, S.P.,

brasil. * * I n s t i t u t o de Quimica, quara,

U n i v e r s i d a d e E s t a d u a l Paulista,

CP 174, CEP 14800, A r a r a

S.P., Brasil.

(Received 6 February 1978; received for publication 22 August 1978) Abstract S o l i d complexes of some tertiary p h o s p h i n e oxides w i t h n e o d y m i u m te have been p r e p a r e d and c h a r a c t e r i z e d by analysis, ne solutions,

IR and visible spectroscopy.

L= TPPO, BDPPO, phenyl-,

DBPPO, TBPO,

tribenzyl-,

TEPO or TMPO

(III) nitra-

c o n d u c t i v i t y in n i t r o m e t h a -

The general formula

is

Nd3(NO3) 3L3

(triphenyl-, b e n z y l d i p h e n y l - ,

triethyl- and t r i m e t h y l p h o s p h i n e

dibenzyl

oxide respectively).

Introduction The p h o s p h i n e oxides as p o t e n t i a l investigations gands with

lantnanide

particularly

ligands have been the subject

as shown by two recent reviews (III) n i t r a t e s

the IR data,

are known

of

several

(1,2). Some complexes of these li(3,4,5).

These papers

c o r r e l a t i n g them w i t h p r o b l a b l e structures

considered and

nature

of the bonds. In the p a p e r our o b j e c t i v e is to study a n u m b e r of n e o d y m i u m

(III)

nitrate

complexes with some aryl and or alkyl- s u b s t i t u t e d ligands and make correlations of the IR and visible s p e c t r a with p o s s i b l e changes in the structure of the complexes.

The T P P O c o m p l e x is already known

have a continuous series

(6) we d e s c r i b e d the synthesis and the

compounds of aryl- s u b s t i t u t e d p h o s p h i n e oxides with

(III) p e r c h l o r a t e ,

to

for consideration.

In an e a r l i e r p u b l i c a t i o n of c o o r d i n a t i o n

(3) and is i n c l u d e d here in order

the general formulas of which are

properties neodymium

[NdL4(CIO4)21CIO 4 ,

and

e v a l u a t e d the i n f l u e n c e of s u b s t i t u t i o n on the p h o s p h o r o u s on some p r o p e r t i e s of the compounds. It is w e l l known that the nitrate ion has a g r e a t e r c o o r d i n a t i n g capability toward the lanthanide ions and that this results, of n e u t r a l complexes whereas perchlorate

in general,

in the

c a t i o n i c complexes are more often formed

formation with

the

ion. D i f f e r e n c e s in steric requirements also result in changes in the

s t o i c h i o m e t r y d e p e n d i n g on which anion is p r e s e n t It is s u g g e s t e d in some papers in rare earths

coordination

(3,4)

compounds with p h o s p h i n e oxides, giving in these case

a c o o r d i n a t i o n number of nine. M o r e o v e r this b i d e n t a t e b e h a v i o u r

(7).

that the nitrate ion w o u l d be b i d e n t a t e

there is some s t r u c t u r a l evidence

(8,9,10). 419

for

420

Complexes of Neodymium(Ill) Nitrate Experimental

Preparation

of the li~ands

ly described Preparation

- TPPO, BDPPO,

(6). TEPO and TMPO of complexes

of neodymium

in the molar ratio of i/3 (Nd/L).

rated after several

hours at ambient

washed with cold solvent

The precipitate

temperature

of

in ethanol.

The

solid

apparatus

was

( 78 ° C

from a benzene

solu-

In those cases the molar

ratio

(Nd/L).

was 1/6 Analzsis

- The complexes were analysed as described previously

ion was determined

by precipitation

and N in the TMPO and TEPO compounds of the Instituto lutions

as nitron nitrate.

- Conductivity

A

microanalysis

data were obtained

tion prepared

The IR spectrum

in 10-3M nitromethane

viously

(ii).

The visible

absorption

Results General

- Analytical

values

Vibrational

spectra - Table

ching vibrations of vibrations.

(gpo)

These complexes

coordinated

for which we

in a glove box.

to the metal

complex form~

ion.

It contains

a tentative

assignment

and ligands

and also of some nitrate m o d ~

The spectra of the complexes

are presented

in order to characterize

tion of Vpo in the free ligands are attached

cussed in the literature

changes

of the P-O stret -

in Figure

the compounds.

I. The assig~ -

(13,14).

The

posi-

to higher energy when more electronegati-

to the phosphorous

atom as has been extensively

The observed position

can he related to the order and polarity of the ligands

used

are very hygroscopic

ments were made by comparison with other data found in the literature.

basicity

in

in the complexes

The IR data were obtained

ve substituents

in a

are presented

are low and in agreement with a neutral groups

sieves

around 70 per cent. The gen~

just TMPO and TEPO and the solid samples were handled (12) with the nitrate

nu-

as described pre-

and molar conductances

method gives overall yields

of ligand in the synthesis.

Molar conductance

cm -I) in

in a CCI 4 sol~

over molecular

spectra were obtained

ral formula is Nd(NO3) 3L 3 even for the TMPO and TEPO complexes a large excess

so-

and Discussions

data, melting points

table I. The preparative

(4000-250

of TEPO was obtained

from CCI 4 that had been dried previously

extractor.

for C , H

Microanalysis

The IR spectra of the li-

gands and complexes were obtained with a Perkin Elmer 457

Soxhlet

of

nitrate

de Sao Paulo.

at 25.0°C using a Methrom E 365 B Konduktoskop~

jol mulls between CsI plates.

(6). The

was made by the Laboratory

de Qufmica da Universidade

Physical measurements

lation

ethanolic

to a hot ligand

which formed was sepa-

by decantation.

TEPO and TMPO were isolated

of their high solubility

as previou~

in anhydrous

nitrate hexahydrate

and dried over P4010 in an Abderhalden

and 2 mm Hg). The complexes tion because

obtained

were used as received.

- The complexes were synthesized

medium by addition of a solution solution

DBPPO and T B P O ~ r e

(Kand K Laboratories)

of ~PO for the

dis-

ligands

of the P-O bond in the following way.

The

is a function of the charge on the oxygen atom and there-

fore related to the participation of the oxygen lone pairs in the multiple bond. Correlations between phosphine oxide donor properties have previously made with the ~¢ parameters

of the substituents

(1,15).

P-O been

421

Complexes of Neodymium(Ill) Nitrate TABLE I Analytical

Data (a) , Melting

Complex

% Nd

Points

and Molar Conductances.

% NO 3

% L

AM

M.P.

(°c1 12.0

Nd (NO3) 3 (TPPO) 3

15.5

(12.38)

Nd (NO3) 3 (BDPPO) 3

Nd (NO3) 3 (DBPPO) 3

11.9

15.4

71.7

(15.361

(72.66)

11.4

14.5

72.1

(11.51)

(14.85)

(73.60)

13.4

(11.17)

Nd (NO3) 3 (TMPO) 3 (e)

(a)

5 . 6 8 (bl

2 9 . 7 0 (c)

(5.73) (b)

(29.50) (c)

23.6 (23.78)

6.81 (b) ( 6 . 9 3 ) (b)

18.14 (c) ( 1 7 . 8 2 ) (c)

signments

for the benzylphosphine

oxides.

This assignment

Green admitted

The strongest

is uncertain

that one of the components

considered

bonds

decreases

The TMPO vibrational TEPO the vibrational

appears

ligands

195.2-195.7

2.0

130.2-133.4

190.3-191.2

as a doublet

% H - Theor.

and

was due to a C-H vibration

oxides

=

First

asof

Deacon

and

of the ring.

is the most intense

and was

of inter- or intramolec~

through the methylene

the P-O bond order and also VPO

ble to have non-equivalent

3.3

band just below 1200 cm -I

reason is the possibility

in benzylphosphine

218.8-219.5

for several reasons.

the lower energy component

as the UPO" Another

far hydrogen interaction

of TPPO,

4.5

(16) on TPPO we have made tentative

all, in the solid state this band generally With the exception

184.1-185.1

(b) % N ; (c) % C ; (d) 4 . 4 9 , Exp.= 4 . 4 8 .

the work of Deacon and Green

was assigned to ~PO"

9.0

(74.42)

(19.69)

Theoretical data within parenthesis; 6 . 1 9 , Exp. = 6 . 6 2 ; (e) % H - T h e o r . = Following

73.5

(14.40)

19.5

Nd (NO3) 3 (TEPO) 3 (d)

241.5-242.0

(71.65)

(11.91)

10.5

Nd (NO3) 3 (TBPO) 3

69,4

(15.96)

~-Icm2mol-i

groups.

(171" Moreover

This

it is possi-

in the solid state giving more than one ~PO'

modes have been studied in several papers

(18,19,20).

For

data were not available in the literature. The Vpo for a CC~ -i . In the solid state this value probably will be

solution was found at 1168 cm lower. The assignments frequencies

(21,221

for this ligand were made considering

and such similar compounds

The IR data and a tentative Table

assignment

as triethylphosphine

group

(23) and TMPO.

for TEPO and its complex are presented

in

Ill.

Due to the fact that the UPO position or phenylphosphine city.

characteristic

oxides,

it is difficult

The same occurs with methyl

is almost

the same for the benzyl-

to correlate

and ethylphosphine

and

these data with the basi-

oxides.

422

Complexes of Neodymium(III) Nitrate

rPPO

BDPPO

E)BPPO

TBPO

r£Po

TMPO

1400

1000

600

FIG.

Vibrational In the complexes bands

are observed

sis we calculed between vities

~PO appears

spectra

cm "1

I

of the complexes.

at lower wavelenghs

and we have assigned

than in the ligands.

Several

as ~PO the most intense ones. On this ba-

the Agpo in the complexes

(Table II]. Figure

It shows the rela~ons

gs ~ or E~ and A~po, where Ez is the sum of the substituent

electronegati-

(14). The result is a linear plot.

The IR spectra also indicate very difficult

to decide whether

veral considerations

that nitrate

ions are all coordinated

the coordination

but it is

is mono- or bidentate

have been suggested for this purpose but

(24). Se-

only in some cases

Complexes of Neodymium(lll) Nitrate

423

TABLE II IR

Compound

VPO (cm-l)

TPPO

1193 (vs)

[Nd(NO3) 3 (TPPO) 3]

p159

A~po

34,40

L11s3(vs) BDPPO

Data

~ ( N O 3 ) (BI)

11310(vs)

~2 (NO3) (AI)

~6 (NO3) (B2)

I032(s)

820(m)

LI3OO(vs)

1185 (vs) 820(m) LI090 (vs)

DBPPO

I185 (vs)

[Nd(NO3) 3 (DBPPO) 3]

ii08 (vs)

TBPO

ll90(vs)

TEPO

1168 (vs) Ca)

[Nd(NO3)3 (TEPO)3]

Ii150 (sh)

TMPO

1160 (vs ,b)

[Nd (NO3) 3 (TMPO) 3]

[~152 (sh) ll5 (vs ,b)

[illS(s)

L1290(vs)

LI038 (m)

L1293 (vs) f1322

[~032 040 (s) (m)

[840 Cm)

[1288 (s)

L1038(m)

Ls3s (m)

18,53

1310(s,b)

i035 (m)

822 (m)

20,57

1300(vs,b)

1035 (m)

822(m)

77

r820cm)

(a) v3(Al) and ~5(BI) masked by ligand absorptions, assignments being made considering NO~ ion as bidentate (261. (b) CCl 4 solution. have they led to satisfactory results. One of these (25) makes use of a combina tion bands that appear as a doublet around 1750 cm -I. In this region the ionic nitrate group exhibits a single band assigned to a combination of the ~I(AI) and u4(E) modes. In the coordinated nitrate group the degenerate mode is split into two components u3(Al) and Us(Bl) so that the separation in the doublet is similar to the v 4 mode. This splitting would be greater in the bidentate nitrate group than in the monodentate one. Only in the TMPO complex did we observe two weak bands at 1735 and 1768 cm -I that can be assigned to this combination. The splitting is within the range found for lanthanide complexes containing bidentate nitrate groups (26). Electronic spectra - The electronic spectra of the complexes were studied in the 419/2÷2Pi/2 (430 nm) region as well as in the region of the hypersensitive

424

Complexes of Neodymium(Ill) Nitrate TABLE III IR Absorption of TEPO and the Neodymium Complex.

TEPO*

[~

960(vs)

930(s) 900(s) 875 (s)

Tentative assignments

TEPO*

L~~d(NO3)3(TEPO)~**

[CH3 asym. and [~ym. s t r . H2 asym. and Lsym. s t r .

11270 (sh)

[I 280 (sh)

235(vs)

L125o (w)

1168(vs)

Tentative assignments CH2 wag

Fl150(sh) LlllS(s)

P-O str.

1735(m) 1455(s)

CH 3 asym. def.

1405(m)

CH 2 def.

i1375(w) 368(w)

CH 3 sym. def.

i080(sh) 1070(sh)

11038 fro) 020(sh)

lO4S (w) 020 (vw) 98S (vw) 8s (m)

C-CH 3 rock C-C str.

[~

P-C sym. and

773s (m) 2 s (w)

CH 2 rock

7s (m)

asym. str.

62s (m) 4so Cm)

CPO def.

*CCI 4 solution **nu3ol mull.

4I 9/2÷4G5/2 , 2G7/2

{S60-610 nm)

With the exception of the complexes

and TBPO all the compounds have similar hypersensitive transitions. ty of these bands indicates a similar environment for Nd(III) presents a spectrum o f ~ d ( N O 3 ) 3 ( D B P P O ) ~

(27) . Figure

III

that is typical for the majority of

the

complexes and a spectrum of ~ d ( N O 3 ) 3 ( T M P O ) ~ ne solution

of TMPO The similari

. A spectrum of a 1,2-dichloroetha -

(c = 3x10-3M) of t h e ~ d ( N O 3 ) 3 ( D B P P O ) ~

shows no differences

in

the

hypersensitive bands compared to the solid state. For the 4I 9/ 2+2Pi/2 transition the crystal field could appear as three or five bands depending on whether it is cubic or non-cubic (28) because the excit~ state can not be split . This

band is a very convenient one from which to deter

mine the nephelauxetic effect (29) and the position of this transition has also been related (30) to the environment around the Nd(III). All spectra present a band and a series of very weak bands at a lower energy that are difficult localize Only for the

~d(NO3)3(DBPPO)~ was it possible to define the

to

position

of the five components. Starting with these values we calculated the center of gravity of the transition to be 23092 cm -I. The most intense band is at a higher energy (23267 cm -I) and we considered that this band corresponds to the transition of the component of the fundamental level which results in a crystal field

Complexes of Neodymium(Ill) Nitrate

425

1,oCo¢ ~T~

TPPO

7.5

7.C

2.0

BDPffO DSPP/

6.5-

J

6.0 100

TMPO 3.0 TEPO

i

80

4'o

6'0

20

5Vpo

FIG. Relation oZ~

between

II

~ (and a ¢) and the average

AVpo.

, xZa ~ .

*AVpo for this complex -I

was obtained

from the band

at 1130 cm

4~o

'

Eletronic

4~o

5~o

'

5&o

'

6oo

FIG.

III

Spectra-

(a)

[NdfNO3)3(DBPPO)3 ]

~b)

~ d (NO3) 3 (TMPO) 5]

.

426

Complexes of Neodymium(Ill) Nitrate

stabilization of 175 cm -I . The relation between this center of gravity appropriate value

and the

(29) for LaF 3 doped with Nd 3+ (23270 cm -I) is 0,992, that is 8,

the nephelauxetic coeficient.

The position of the most intense component

is

(4300 ± 2)A for all complexes. Also the center of gravity of the hypersensitive transition is (5855 ± S)A for all compounds,

calculated by graphic integration.

Through the similarity of the spectra and the values of the center of gravity we can conclude that the Nd(III) makes no distinction among the ligands. The position of the ligands in the nephelauxetic series could be established by the va lue of B or by the 419/2÷2Pi~ 2 frequency
(51,32): F-
Aknowled~ments The authors are grateful to Professor Larry C. Thompson of the University

of

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Complexes of Neodymium(Ill) Nitrate

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,