Mass spectra interpretation of some thiophosphororganic compounds

Journal of MOLECULAR STRUCTURE Journal of Molecular Structure 348 (1995) 393-396

Mass spectra interpretation of some thiophosphororganic compounds Z.Moldovana, S.Nicoarab*, M.Culeaa, O.Cozarb, I.Fenesana,P.Vegha and J.J.Riosc aInstitute of Isotopic & Molecular Technology, 3400 Cluj - Napoca 5, P.O. Box 700, Romania bphysics Department, Technical University, 15 Daicoviciu str. 3400 Cluj - Napoca, Romania cInstituto de la Grasa y sus Derivados, 41012 &villa, Spain The fragmentation pattern of six thiophosphonic-amyd-aryl-sulphonimido derivatives is presented. The electron impact mass spectra were recorded at 70 eV. High resolution mass measurements and metastable analyses were performed to elucidate the ions composition and the fragmentation processes. 1. INTRODUCTION Due to their biological activity, the organophosphorus compounds are extensively studied [l41. This paper discusses a series l-6 of the newly synthesized [5] S-methyl derivatives of the p-R substituted arylsulphonimides of the dimethylamydo - cyclohe$thiolphosphonic acid :

The aim of this work is to study the fragmentation pattern of molecules l-6 by electron impact mass spectrometry(EIMS). 2. EXPERIMENTAL The spectra were obtained on a MAT 3 11 double focusing mass spectrometer set at : 70 eV electron energy, 60 p.A electron emission, 800 resolution and 150°C ion source temperature. The direct inlet system was maintained between 60-125°C depending on the compound. High resolution (HR) mass measurements were made using the peak matching unit and metastable transitions were registered by both MIKE and HV techniques [6], for compound 2. 3. RESULTS AND DISCUSSION The mass-to-charge ratios and relative abundances of the main ions are listed in Table 1. The characteristic fragmentation processes are presented in Scheme1 and the mass spectrum of2 isshowninFig.l. The molecular ion Ma has low intensity, probably due to the ramification of the molecules studied . Ion a, m/z 344+R is produced from I@* by simple &xrion of the S-C bond and elimination of CH3. Metastable ions detection confirmed the process and also the subsequent elimination of NCZH~, resulting the ion b, m/z 3Ol+R, which was confirmed by HR measurements. Metastable transitions proved that ion c&z 253+R is formed from b by loosing the SO group, like in other molecules with SO2 [7]. * author to whom correspondence should be addressed 0022-2860/95/%09.50 0 1995 Elsevier Science B.V SSDI 0022-2860(95)08671-4

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394

80

154 138

245 331

65

h

252

7581

20 -'

183 174 200

i0 'l 10 -' 02

316 292 359 268

Figure 1. Mass spectrum of 2 at 70 eV Table 1 Mass spectral data for compounds l-6 (direct inlet temperature “C)

Ion

l(85 “C )

M(359+R) a(344+R)

360(2) 345(4)

b(301+R)

302(2) 254(2) 3 17(2) 238(6) 278( 1) 234(6) 141(22) 125(7) 109(6) 23 l(8) 188( 1) 124(6)

c(253+R) d(3 16+R) e(237+R) fi277+R) g(233+R) h( 14O+R) k( 124+R) Z(108+R) m(230+R) n( 187+R) L o( 123+R) p( 185+R) r(76+R) ~(92) base ueak

186(3) 77( 100) 92(80) 77(100)

m/z (relative abundance %) 2(110 “C) 3(80 “C) q125 “C) 374( 1) 438( 1) 394( 1)

y120 “C) 378( 1)

6(60 “C) 375(7) 332(4) 284( 1) 347( 10) 268( 16) 308(3) 264( 10) 171(29) 155(25) 139(3 1) 261( 15) 218(2)

359(8)

379(3)

423(3)

363(3)

316(12) 268(5) 33 l(33) 252(23)

336(2) 288( 1) 35 l(7) 272(6) 3 12(3) 268(6) 175(7)

380(2) 332( 1) 395(5) 3 16(7)

320(2) 272(0.3) 335(8) 256(4)

159(7) 143(3) 265( 12) 222(2) 158(5)

356( 1) 3 12(5) 219(23) 203(6) 187(6) 309(7) 266(2) 202(3)

296(3) 252(6) 159(25) 143(6) 127(3) 249( 10) 206(2) 142(5)

220(2) 11 l(20) 92(35) 44(100)

155(70) 92(50) 44(100)

292(11) 248(33) 155(25) 139(33) 123( 18) 245(37) 202(4) 138(37) 200(6) 91( 100) 92(90) 91(100)

264(2)

204(2) 95(86) 92(25) 44(100)

390(2)

154( 14) 2 16(6) 107(30) 92(70) 55tloo)

395

b

a

T WI +. %"2

1+

*2CH3

I

SCH, Qh=N-SOm H ci

so2

z*

5 &=N*R H e Cl

*2 SCH3 I Hh=N-SO$$R kCH& FH8

m

P=N-SC-J~~R

HI$CHd 2

HN(CH,), .+2 = +=N-io2*R

P

ml Scheme 1.Main fragmentation pathways of molecules l-6 under 70 eV EIMS ( * = metastable ions detection )

Ion l@. undergoes the H transfer from N to P by a four membered transition state, prior to the loss of the neutral fragment NCzHs and produces the ion d, m/z 316+R, transition supported by the metastable analysis. Ion d looses both CH3 and SO,, as demonstrated by metastable ions detection and forms the ion e, m/z 237+R, in Scheme 1, confirmed by the HR measurements. Ion MS may also undergo the H transfer from the cyclohexil to P, a specific reaction for molecules with P [7] and generates ionf, m/z 277+R by eliminating C&o, as encountered in other studies on thiophosphororganics [S]. Ion g, m/z 233+R may result fiomfby simple fission. Metastable transitions indicated the formation of h, m/z 14O+R from g, as well as the transitions h -- i, m/z 154 and i--j, m/z 138. Ions i and j are found only in the spectrum of 2 and were not inserted in Table 1, involving the occurrence of the tropylium cycle, a process remarked for compounds with substituted phenyl

PI.

396

Metastable transitions indicated thatf eliminates SCH3, giving ion m, m/z 23O+R The latter undergoes the rearrangement of H from CH3 to P, subsequently loosing NCzHs and resulting the ion n, m/z 187+R Ion n might form ion o, m/z 123+R, by eliminating SO2, a typical reaction for molecules with SO:! [4]. Ion m probably turns into its isomer ml which looses the group I-IN(CH& and forms the ion p, m/z 185+R Metastable transitions evidenced this fragmentation as well as the formation of ion 4, m/z 153 from m, by eliminating the fragment C7H8. All spectra exhibit important peaks for ion r, m/z 76+R which is the base peak for 1 and 2. Accurate mass measurements conlirmed for this ion the structure C&R For all the compounds, an intense ion was observed at m/z 92 and I-IR mass measurements led to the structure (CH&NSO which involves the migration of certain groups of atoms, as remarked for other phosphoro-thioesthero compounds [lo]. In all spectra at m/z 44 the intense ion N(CH& was conftrmed by HR mass determinations. This ion may result from I@. by simple fission and represents the base peak for 3-5. In all cases were found the known ions at m/z 76, 51, 50 I?om the fragmentation of the phenyl group and at m/z 83, 55,43, 4 1 from the cyclohexyl cleavage [8]. For 6 the base peak rises at m/z 55 with the elemental structure confirmed to be C4H7. 4. CONCLUSIONS Mass spectra of 1-6 show ions formed by simple fission followed by the loss of the fragments N(CH&, SCH3, CH3, 0 and H. Many fragment ions undergo rearrangement processes, subsequently eliminating the neutral molecules or radicals: C&c, NCzHs, HN(CH&, SCH2, SOZ, SO, C&j, CH3+SOz. Heavy ions exhibit more intense peaks in 2 and 6 probably owing to the electrodonating properties of CH3 and OCH3, that provide more stable structures in 2 and 6 than for the other compounds. :

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