Complexes of Rh(III), Ir(III), Pd(II), Pt(II) with dimethyl(1-naphthyl)arsine

INORG.

NUCL.

CHEM.

LETTERS

Vol.

11,

pp.

319-322,

1975.

Pergamon

Press.

Printed

in

Great

Britain.

COMPLEXES OF Rh(III),Ir(III),Pd(II),Pt(II) WITH DIMETHYL(I-NAPHTHYL)ARSINE.

L.Sindellari, L.Volponi, and B.Zarli.

Istituto di Chimica Generale dell'Universlta', Via Loredan, 4 35100 - PADOVA - ITALY. (Received 25 November 1974)

A recent paper reports that the dimethyl(1-naphthyl)phosphine in complexes of rhodium(III) and iridium(III) undergoes internal metallation reactions in the 8-(peri-) position (1). In order to investigate the ability of the analogous dimeth yl(1-naphthyl)arsine (L) to give internally metallated compounds, we examined the reaction products of this ligand with rhodium(III) and iridium(III). In addition the study has been extended to pa~ ladium(II) and platinum(II). The

rhodium and the iridium readily gave octahedral comple~

es of formula MX~L~

(where M = Rh or Ir; X = C1 or Br) by adding

ethanolic solutions of the ligand to aqueous solutions of the a~ propriate metal halide. The complexes are listed in the Table, along with some analytical and spectral data. We were unable to prepare metallated compounds, even on prolonged heating either of the reactants or the complexes in various solvents and in the presence of a base. However, after refluxing in 2-ethoxyethanol for several hours in the presence of sodium acetate, the iridium complexes gave mixtures of metallated and unmetallated products, which we could not separate. Successively we attempted to effect similar reactions with palladlum(II) and platinum(II). When ~ M ~ (where M = Pd or Pt; X = C1, Br, I, or SCN) was treated with dimethyl(1-naphthyl)arsine in water-ethanol at room temperature, 319

orange-red

yellow

brown

orange

orange-red

light-yellow

light-yellow

cream

RhBr~L~

IrCI~L~

IrBraL ~

PdBr~L~

Pd(SCN)~L~

PtBr~L~

Pt(SCN)~L~

Pt(As-C)LBr

170 °

135 °

220 °

65 °

193 °

186 °

194 °

214 b

209 °

m .p.

C

38.7 (38.9)

39.9 (40.2)

3.4 (3.3)

3.4 (3.3)

3.2

(3.1)

35.0

3.9 (3.?)

3.6 (3.5)

3.4 (3.4)

4.0 (4.O)

3.7 (3.7)

4.3 (4.3)

H

(35.1)

45.2 (45.4)

39.6 (39.5)

38.0 (38.2)

43.6 (43.5)

41.7 (41.5)

47.5 (47.7)

The calculated values(%) are in parentheses.

orange

C OLOUR

RhCI~L a

COMPOUND

10.8 (10.8)

(19.5)

19.3

21.6 (21.9)

21.1 (21.2)

10.4 (10.6)

23.3 (23.1)

12.0 (ll.7)

Hal.

3.5 (3.6)

3.9 (4.0)

N

S

8.3 (8.2) 192s

212s, 196s

215sh

233mw

313s

235m

338s, 322sh

~ (M-X )

of the complexes.

9.1 (9.3)

TABLE.Some analytical data and idetal-Halogen bond stretching frequencies(cm-')

o

Vol. 11, No. 5.

Dimethyl(1-Naphthyl)Atsine

321

square-planar complexes of formula MX~L~ were isolated. While this work was in progress, a paper reporting some of our compounds has been published (2). The complexes prepared by us, and not described earlier, are in the Table. The far infrared spectra of the bromo-complexes should indicate a c!s-configuration. Definitive structural assignments are not possible for the thiocyanato derivatives. However the bands observed in the C-N -1 stretching region at 2087 cm and at 2111 cm -1 for the palladium complex, and at 2106 cm -1 and at 2131 cm -1 for the platinum analogue, would suggest a coordination of the thiocyanato group to the metal through the sulphur atom. The remaining bands of the SCN group could not be clearly assigned owing to the absorptions of the ligand in the expected regions. The palladium complexes showed no tendency to undergo internal metallation. In fact the reactions performed in various ex perimental conditions, led either to decomposition or to recovery of the starting compounds unchanged. Such a behaviour has been already described in ref.(2) for the chloro- and iodo-derivatives. The platinum complexes gave m~tallated compounds of formula PtX(As-C)L (where As-C = C4oHeAsMe~; X = Cl, Br, or I). The complex PtCl(As-CiL and its iodo-analogue were prepared with methods similar to those of the literature(2). The complex PtBr(As-C)L was isolated after refluxing for

an hour PtBr~L~

in

2-ethoxyethanol containing sodium acetate in excess on the stoichiometric amount. The 1H n.m.r, spectra of the chloro- and iodo-complexes agree with those reported in the literature(2). The spectrum of PtBr(As-C)L showed two l:l singlets at v 9.12 and at v 8.03 due to the methyl hydrogens on the ligand. The corresponding resonance for the unmetallated PtBr~L~ at T 8.31 was a slnglet, implying the equivalence of the methyl groups. The naphthyl hydrogens of PtBr(As-C)L formed a complex pattern spread over a T range (1.6-2.9) smaller than the corresponding range (1.3-3.9) found for the unmetallated compound. The T values in the former com

322

Dimethyl(l-Naphthyl)Arsine

Vol. 11, No. 5,

pound are similar to the ones in the free ligand (1.5-2.9). The far infrared spectrum of P t B ~ L ~ exhibits bands at -1 -1 212 cm and at 196 cm , which could be assigned to Pt-Br bond stretching vibrations. The spectrum of PtBr(As-C)L shows in this -1 region only one band at 192 cm , as we expected. This work indicates that reactions of the dimethyl(1-naphthyl)arsine with halides of rhodium(III), iridium(III), p a l l a dium(II) and platinum(II) yield complexes in which the metals exhibit their most usual configurations. Attempts to effect m e tallation reactions led us to isolate internally metallated c o m plexes of platinum and provided some evidence of metallation in the case of iridium. Therefore the behaviour of the dimethyl (1-naphthyl)arsine seems to be similar to that of the correspond ing phosphine, even if a lower ability of the arsine to give metallated complexes could be remarked.

References 1. J.M.Duff and B.L.Shaw, J.Chem.Soc., Dalton, 2219(1972). 2. J.M.Duff, B.E.Mann, B.L.Shaw, and B.Turtle, J.Chem.Soc., Dalton, 139(1974).