Oxidative Addition Reactions of P(CN)„ P(NCO)3 and P(NCS), to (I

Oxidative Addition Reactions of

P(CN)„ P(NCO)3 and P(NCS), to (i/5-C5Me5 )Co(CO)2

M- S. Delgado*, M- J. Macazaga, and J. R. Masaguer Departamento de Qufmica Inorgänica, Universidad Autönoma de Madrid, Cantoblanco, Madrid-34, Spain. Z. Naturforsch. 39b, 142 — 144 (1984); received October 3, 1983 Phosphorus Pseudohalogens, IR spectra, Cobalt The phosphorus pseudohalogens P(CN)3, P(NCO)3 and P(NCS)3 react with (?/5-C5Me5)Co(CO )2 to give the complexes (? 75-C;Me5)Co(CO)XPX 2 (X = CN, NCO, NCS). All the compounds are characterized by elemental analysis, IR. electronic and ’H NMR spectra.

Introduction teristic of terminal ligands [ 6 , 7]. For each complex, The oxidative addition of pseudohalogens to coor- the assignment of these band to the two types of dinatively unsaturated organometallic compounds ligands is difficult because the proximity of their fre gives rise, to the formation of the corresponding quencies. pseudohalogen derivatives. Thus oxidative additions The range of stretching vibration v(CO) for the three complexes is also typical of terminal ligands to (?75-C5H 5)Co(CO)2, (^ 5-C5EtM e4)Co(CO ) 2 [1] and [6], (?7:'-CsMe5)Co(CO ) 2 [2] have been studied. In all cases the elimination of a carbonyl-group and the For the complexes oxidation of Co(I) to Co(III) takes place. (^5-C 5Me5)Co(CO)(NCX)P(NCX ) 2 (X = O, S), the In the present work we employ the phosphorus stretching vibration v(CO) (cyanate) is observed at 1320 cm-1, while the v(CS) (thiocyanate) is not ob pseudohalogens P(CN)3, P(NCO ) 3 and P(NCS)3, the reactivity of which has been studied with volatile served because it is masked by the strong band y(CH) of the cyclopentadienyl ligand. halides of transition metals such as TiCl 4 and ZrCl4 [3], but which are utilized in oxidative addition reac In the cyanate complex the vibrational frequencies tions for the first time. v(CN), v(CO) and (3(NCO) indicate that the coordi nation to metal is via the N atom [7], For the thio Results and Discussion cyanate complex the determination of the internal standard ratio of y(CN) of the SCN band by the The addition of P(CN)3, P(NCO ) 3 and P(NCS) 3 Bailey mehtod [ 8 ] indicates that the coordination is solutions in benzene to ether solutions of (rj~- also via the N atom. C 5Me5)Co(CO)2, in an N 2 atmosphere, gives rise to In the range 595—550 cm -1 appear the bands the release of CO and precipitation of solids with the corresponding to v(P—C) for the complex following stoichiometry: ( 7/''-C5Me5)Co(CO)XPX 2 (/75-C5Me5)Co(CO)(CN)P(CN ) 2 [9], and those cor (X = CN, NCO. NCS). These compounds are hy responding to the vibrations (3(NCO), <3(P—NCO) groscopic and sparingly soluble in solvents such as and (3(P—NCS) for the complexes (rf- benzene, nitrobenzene, or dichloromethane. C 5Me5)Co(CO)(NCX)P(NCX ) 2 (X = O, S) [10, 11], IR spectra of the compounds display, in the In the range 490—418 cm -1 appear the bands cor 4000—200 cm -1 range, characteristic bands of the responding to v(Co-CN) and v(Co-CO) together pentamethylcyclopentadiene ligand with C5v symme with those of the deformation vibrations of these try [4, 5], Table I gives the bands corresponding to bonds [ 6 ]. The vibrations (3(P —CN) and <3(NCS) are the carbonyl, cyanide, cyanate. thiocyanate. P(CN ) 2 also observed. and P(NCX ) 2 (X = O. S) ligands, together with In the complex RCo(CO)(NCS)P(NCS ) 2 the vi those corresponding to the metal-ligands bonds. brations v(Co—ring), d(P—NCS) and v(Co—N) are The range of stretching vibrations v(CN) is charac expected to be involved in the intense broad band observed at 320 cm-1. * Reprint requests to M? S. Delgado. The electronic spectra of the complexes in di 0340- 5087/84/0200- 0142/S 01.00/0 chloromethane solution are set out in Table II. M- S. Delgado et al. • Oxidative Addition Reactions 143

Table Ia. IR spectral data for the complexesb.

RC o(CO)(CN)P(CN)2 RC o(CO)(NCO)P(NCO)2 RC o(CO)(NCS)P(NCS)2

2.170 m v(CN) 2.220 v. s. v(CN) of 2.150 m • of 2.160 v. s. NCO and P(NCO)2 2.110 s v(CN) of (NCS) 2.130 w, sh (CN) and P(CN)2 (2.2) 2.040 w v(CO) 2.045 s v(CO) 2.060 m v(CO) 1.320 w v(CO) of (NCO) 1.950 m. br. v(CN) of P(NCS)2 590 v. s. • v(P -C ) 580 s 595 m <3(NCO) and 550 m d(P-N CS) 587 m (3(P—NCO) 490 sh, w <5(P—CN) 470 m <5(NCS) 470 m i/(Co-CO ) 485 m, br v(Co —CO) and 450 m, sh v(Co—CO) and 465 w, sh d(C o -C O ) 469 m 440 w d (C o -C O ) d(Co—CO) 435 w v(Co—CO) and 450 w 418 w d(C o-C N ) 350 m v( Co—ring) vCo—ring) 340 w v( Co—ring) 320 v.s.,br d(P-N C S) and 300 v. w. <3(P—NCO) v(C o-N ) 315 v. w. 280 w v(C o-N )

a In cm b R = ^5-C5Me5:; in parenthesis, the internal standard ratio determined by Bailey method [8].

Table II. Electronic spectra of the complexes3.

RC o(CO)(CN)P(CN)2 RC o(CO)(NCO)P(NCO)2 RC o(CO)(NCS)P(NCS)2 Assignation

20.161 sh, br 16.393 16.501 sh, br 1 d -d 17.301 sh, br J 27.322 27.800 27.777 charge transfer

In cm CH2C12 solution, R = >75-C5Me5.

If we assume the complexes to be octahedral, the Experimental simultaneous presence of CO, X (X = CN, NCO or All reactions were carried under oxygen-free N2. NCS) and PX2 ligands reduces the symmetry to Cs. In The pentamethylcyclopentadiene [14], (rj5- this way the triply degenerate t2g are split into the C 5Me5)Co(CO ) 2 [15] and the reactants P(CN ) 3 [9], components e and b 2 and the doubly degenerate eg P(NCO ) 3 [10], P(NCS) 3 [11] were prepared by the orbitals are split into a] and b l5 as previously ob published procedures. served in the photoelectronic spectra of carbonylcy- The cobalt was determined by titration of the Co- clopentadienyl complexes of C2v symmetry [12, 13]. EDTA complex in presence of NET as indicator. For Cs symmetry a greater splitting can be expected, The phosphorus was determined gravimetrically as with the subsequent increase in the width of the ab Mg 2P20 7 [16]. sorption bands. The IR spectra were recorded in the range 4000—200 cm - 1 on a Perkin-Elmer model 325, using This effect is reflected in the electronic spectra Nujol and Hostaflon mulls between Csl windows. which display wide bands, of poor resolution, in the 'H NMR spectra were recorded on a Varian model 16000—20000 cm-1 range, due to d —d transitions, X L-100/15. and an intense band near 28000 cm - 1 brought about The visible spectra were recorded on a Pye Uni by the charge transfer from the metal to the n* orbi cam SP 8 —100 ultraviolet spectrophotometer. tal of CN, CO or NCX. *H NMR spectra display a single signal that can be Preparation on (rj'-C5Me5)Co(CO)(CN)P(CN)2 attributed to the 15 equivalent protons of the 5 In a two-neck flask (100 cm3) fitted with N 2 inlet, methylsubstituents of the ring. magnetic stirrer and pressure equalized dropping 144 M- S. Delgado et al. • Oxidative Addition Reactions funnel, ?7 ''-C5Me5Co(CO )2 (1.5 g, 6 mmole) was dis Preparation o f (rj--C^Me5)Co(CO)(NCS)P(NCS)2 solved in Et20 (30 cm3) saturated with oxygen-free A similar procedure was used with f- N2. A solution of P(CN ) 3 (0.75 g, 6.9 mmole) in ben C 5Me5Co(CO ) 2 (1.5 g, 6 mmole) in E t20 (30 cm3) zene ( 2 0 cm3), freshly obtained, was slowly added and P(NCS) 3 (1.4 g, 6 . 8 mmole) in benzene dropwise. A dark brown solid immediately ap (20 cm3). A brown solid appeared immediately. The peared, and evolution of CO was observed. The solid yield is 1.9 g (75%). was filtered off, washed with Et20 and dried in vac uum. The yield is 1.5 g (75%). C 14H lsN 3OPS3Co Calcd C 39.3 H 3.5 N 9.8 P7.2 Co 13.8, C 14H 15N3OPCo Found C 38.3 H 3.7 N 9.5 P 6.3 Co 13.4. Calcd C 50.7 H4.5 N 12.7 P9.3 Co 17.8, ]H NMR (CDC13): 1.55 d. Found C 49.5 H 4.6 N11.8 P8.2 Co 17.1. ’H NMR (CDC1): 1.65 d.

Preparation of (rj5-C5Me5)Co(CO)(NCO)P(NCO)2 Following the procedure described above, solu tions of 7/5-C5Me5Co(CO ) 2 (1.5 g, 6 mmole) in Et20 (30 cm3) and P(NCO); (1.1 g. 7 mmole) in benzene (20 cm3) were mixed. A blue solid was obtained. The We express our great apreciation of financial sup yield is 1 . 8 g (80%). port from the Comisiön Asesora de Investigaciön Ci4H 15N30 4PCo Cientffica y Tecnica (Spain). Calcd C44.3 H3.9 N ll.l P8.1 Co 15.5, To the Departamento de Quimica Inorgänica de la Found C 43.5 H 4.4 N 12.2 P7.2 Co 15.2. Facultad de Ciencias de la Universidad de Alcala de !H NMR (CDClj): 1.2 (3. Henares (Madrid-Spain) for the elementary analysis.

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