NOTES 2171
VoZ. 7 , No. 10,October 1968 stretching region (3120-3525 cm-l) is complicated and shows bands which may be attributed to uncoordinated and coordinated amine groups. The NH2 deformation mode also consists of two strong bands (1623, 1559 cm-l) indicating two types of amine groups. I n general, the spectrum of the yellow isomer is more complicated than that for the pink isomer indicative of a less symmetric structure for the yellow isomer. The difficulty in obtaining analytically pure samples of the yellow isomer may be attributed to the presence of the uncoordinated amine group. This polar group would have a distinct tendency to hydrogen bond to hydroxylic solvent molecules and also to coprecipitate excess ligand. I n the hydrated form of the yellow isomer the water does not coordinate to the metal ion as shown by the magnetic moment of the hygroscopic complex which does not change significantly as i t absorbs water from the atmosphere. The uncoordinated amine group is probably also responsible for the fact that the yellow isomer is unstable in aqueous solution, precipitating nickel hydroxide immediately. This accounts for the failure to observe this isomer when the preparative reactions are carried out in water.
The reaction between the metal hexacarbonyl and the complexing anion was carried out in methylene chloride solution using a twofold excess of the carbonyl. An immediate difference in the behavior of the two anions was noted. Reasonable yields were obtained with the difluorodithiophosphate anion only when the irradiation was carried to the point where 2 equiv of carbon monoxide was evolved, whereas, with the difluorothiophosphate anion, the reaction could be stopped after 1 equiv of carbon monoxide had been evolved. I n fact, the addition of the difluorodithiophosphate anion to a solution of Cr(C0)S . T H F (THF = tetrahydrofuran) in the absence of light produced only trace amounts of the product. I n both cases the yield was much lower for the molybdenum derivatives than for the others. The chemical analyses (see Table I) and the spectroscopic properties of the products (see Table 11)suggest that the difluorodithiophosphate anion acts as a bidentate ligand, while the difluorothiophosphate anion acts as a monodentate ligand M(CO)6 M(CO)6
+ PFzSz+ PF20S-
+ 2CO M(CO)E,PF~OS-+ CO
-
J
M(C0)4PFzS2-
where M = Cr, Mo, or W. All of the products are yellow solids which are fairly stable in air in the solid state, although solutions are oxidized by atmospheric oxygen. The stability increases from the chromium to tungsten derivatives. CONTRIBUTION FROM R O H MAND HAASCOMPANY, The complexes formed with the difluorodithiophosphate REDSTONE RESEARCH LABORATORIES, anion appear to be more stable than the complexes obHUNTSVILLE, ALABAMA 35807 tained by treatment of the hexacarbonyls with the difluorothiophosphate anion. The analytical data for Complexes of the Group VI Metal Hexacarbonyls the materials prepared are summarized in Table I. with the Difluorodithiophosphate and The proton nmr spectra of the complexes showed the Difluorothiophosphate Anions absence of hydridic hydrogen or paramagnetic impurities. The FI9 nmr spectra are given in Table 111. BY J O H NK. RUFF AND MAX LUSTIG The small change in the P-F coupling constants in the free and complexed anion indicates that only a small Received .Way 15, 1968 change in the amount of s character in the P-F bond has occurred upon c~mplexation.~ The interaction of the group V I metal hexacarbonyls The infrared spectra of the complexes in the carwith electron donors has been widely explored. This bonyl stretching region are quite similar for all the reaction has generally required thermal activation almetals employed regardless of whether the difluorodithough in a few cases (where neutral ligands were emthiophosphate or difluorothiophosphate anions are employed) photolytic activation was found to be appliployed as ligands. I n general, four bands are observed cable. We wish to report the photolytic prepara(see Table 11). To a first approximation this number tion of some new anionic derivatives of chromium, of bands is anticipated for a molecule of the type Mmolybdenum, and tungsten hexacarbonyls involving (CO)L, where L acts as a bidentate ligand bonded to both the difluorodithiophosphate anion and the difluorothe metal in a cis position (C*,, symmetry), whereas thiophosphate anion as ligands. Although a few neufor a monosubstituted metal hexacarbonyl derivative, tral carbonyl complexes of organic dithiophosphates are M(CO)bL, only three bands are expected (C4v symknown'J no anionic derivatives have been prepared. metry). Thus, it would appear that both the PS2F2Furthermore, the use of organic thiophosphates as and POSF2- anions are acting as bidentate ligands. ligands has been little explored, and no known carHowever, the infrared spectra in the P-0 and P-S bonyl derivatives have been reported. Therefore, i t regions (see Table 11) of the complexes containing the was of interest to determine if the recently reported difluorodithi~phosphate~,~ and difluorothiophosphate6 difluorothiophosphate anion as a ligand all exhibit an anions would function as ligands. (4) H. W. Roesky, F. N. Tebbe, and E. L. Muetterties, J . A m . Chem. Soc., (1) F. A. Hartman and A. Wojcicki, Inovg. Nucl. Chem. Letters, 2, 303 (1966). (2) R. L. Lambert and T. A. Manuel, Inovg. Chem., 6,1287 (1966). (3) W. Kuchen and H. Hertel, Angew. Chem., 79, 148 (1967).
89, 1272 (1967). ( 5 ) M . Lustig and 5. K. Ruff, Inoug. Chem., 6, 2115 (1967). (6) H . W. Roesky, Chem. Bev., 100, 950 (1967). (7) E. L. Muetterties and W. D. Phillips, Advan. I x o v g . Chem. Radiochem., 4, 244 (1962).
2172
NOTES
Inorgunic Chemistry 'TABLE I ,kNALY1.ICAL DATAFOR THE COMPOESDS PREPARED RIP, O C
a
Dec p t 135'.
Dec pt 125'.
c
Yield, %
115-117 92-93 99-100 2T3-275a 282-285' 29& Dec pt 130'.
52 19 51 72 15 67
__~C
H
57.3 54.9 49.7 50.0 47.2 42.4
3.58 3.40 3.13 2.86 2.80 2.35
TABLE I1 INFRARED SPECTRA OF THE COMPLEXES PREPARED (aM1) Anion Cr(C0)4PFzs1Mo(C0lrPFSW(CO)PPF~S?Cr(C0)iPFPOSMo(CO)aPFn0SW(C0)5PFnOSPF6- a POSFn-
carbonyl freq---.
2061 2072 2069 2064 2065 2067
--P=S--
m, 1980 m, 1936 vs, 1876 s i l l m, m, 1981 m, 1938 vs, 1879 s 710 m, m, 1975 m , 1928 vs, 1868 s 710 m, w , 1971 m, 1932 s, 1877 s 624 m w, 1979 m, 1934 s , 1869 m 623 m m, 1973 m, 1926 s, 1866 m 623 m 720 m, 648 m
Analytical data---------
Found, yo--N F
1.88 1.58 1.50
4.7 4.2 3.8 5.7 5.4 4.9
7
Calcd, c/a-
7
I -
CO
C
H
s
F
CO
13.0 12.8 11.8 21.0 19.2 17.3
57.5 54.7 19.7 50.3 4T.3 42.3
3.59 3.91 3.10 2.89 2.70 2.43
1.68 1.59 1.45
4 6 4 3 3 9 5 5 5 2 4.6
134 127 116 202 190 17 0
while the complexes containing the difluorothiophosphate anions can probably be written as
P=O 735 s 737 w 735 w 1274 m 1272 m 1274 m
Experimental Section Materials.-The hexacarbonyls of the group VI metals were a See ref 5. b See ref 6. obtained from Alfa Inorganics, Inc. The bis(tripheny1phosphine)iminiuni salt of the difluorodithiophosphate anion and the tetraphenylarsonium salt of the difluorothiophosphate anion TABLE I11 mere prepared by literature methods.5,G THEFly XNR SPECTRA OF THE COMPLEXES PREPARED Preparation of [(CBHL)BP] zNM(CO)SF&-The preparation Chem shift, of all three of the metal derivatives mas carried out in a n analogous Anion ppm ( v s . CClrFj JPI:,cps manner. X mixture of 0.75 g of [ ( C G H S ) ~ P ] Z S P and F~SZ 0.5%g Cr (C0)4PF&12.3 1196 of Cr(CO)s in 25 ml of T H F was irradiated until 45 cm' of gas MO(C0)4PF&12.5 119; ( a t S T P ) was evolved. The mixture was evaporated to dryness W (CO)d'FpS213.6 1200 under vacuum and the residue was extracted with 50 nil of ether. Cr(C 0 ) 5 P F ~ O S 40.2 1128 Pentane was added t o the extract and a 0.82-g sample of product Mo(C0)jPFzOS39.8 1131 was obtained. W(C0)jPFzOS38.4 1136 Preparation of (CeH~)&M(CO)~POSF~.--XlI preparations 2.4 1164 PFzSi- a were carried out in a n analogous manner. For example, a mixPF20S34.2 1098 ture of 0.71 g of Cr(C0)c and 0.99 g of (CGH~)&POSFZ in 50 ml a See ref 5. See ref 6. of CHZC12 was irradiated until 67 cm3 of gas (at S T P ) was evolved. The mixture was filtered and the solvent was removed increase in frequency of the P=O stretching mode and under vacuum. The residue was dissolved in 20 ml of CHzC12, and 80 ml of ether was added. The mixture was filtered and pentane a decrease in frequency of the P=S stretching mode was added t o the filtrate. A 1.08-g sample of product was obover that in the free ion. This strongly suggests that tained. coordination is occurring only through the sulfur8 and Analyses.-The amount of carbon monoxide present in the that the oxygen is free from interaction with a metal complexes was determined by decomposition of the complexes in carbonyl moiety. On the other hand, both of the P=S a pyridine-iodine mixture at 120' for 4 hr. The amount of carbon monoxide formed was measured by means of a Toepler stretching frequencies are slightly decreased in the compump and a calibrated bulb system. Duplicate determinations plexes containing the difluorodithiophosphate anion were made on each complex. Also to ensure t h a t the reaction as would be expected if this ion was acting as a bidenwas complete, each sample tube was reheated for a n additional tate ligand. The reason for the extra band in the CO 4 hr after the initial removal of carbon monoxide. In no case stretching region is not known but may arise from the was more than a trace amount of carbon monoxide found after the second heating. The purity of the carbon monoxide collected fact that the ligand is unsymmetrical and the anion in the calibrated bulb system was checked by mass spectrometry. actually has C,symmetry instead of Cav. This would Conductivity Measurements.-The conductivity of the salts lead to an increase in the number of bands expected. [ ~ C ~ H ~ ) ~ P ] Z ~ C T ( Cand O ) ~(PC F ~H ~B S )~~ X S C ~ ( C O ) ~ Pwas OSFZ The equivalent conductivity of these complexes obtained as a function of concentration in nitromethane solution plotted as a function of concentration suggests that only using equipment previously described . l o The specific conduc1 : 1 electrolytes are present in nitromethane s ~ l u t i o n . ~ tivity of the nitromethane employed was 3.89 X lo-'. For the salt [(C6Hj)3P]2SCr(CO):PFrS~,the molar concentration and Thus, bridged dimers can be eliminated. The structure equivalent conductance (cmz/ohm equiv) are: 5,020 X of the complexes involving the difluorodithiophosphate 73.2; 2.510 X 10-3, 76.4; 1.255 X 79.1; 0.6175 X lo-", anion probably contains four-membered rings, e.g. 80.5; and 0.318 X 82.8. For the salt (Cd&)~hsCr(cO):POSFZ, the same values are: 5.887 X 74.2; 2.944 X S 10-3, 79.3; 1.472 X 10-3, 81.7; 0.7360 X 10-3, 86.4. This / \ Cr(C0)4 PF2leads to a value at infinite dilution of 91.3 and 90.4, respectively. \ / h plot of L A C 'i's. dc gave slopes of 193 and 217, well within S the range accepted for 1: 1 electrolytes. Infraied Spectra.-The infrared spectra of the new compounds (8) I. Linquist, "Inorganic Adduct Molecules of Oxo-Compounds," 740 w
Academic Press, Yew York, N. Y . , 1962. (Y) li. U. Feltham and I
