High Molecular Weight Boron Sulfides - Advances in Chemistry (ACS

15 High Molecular Weight Boron Sulfides I V . Mass Spectrometric Investigation of the Conversion of Metathioboric A c i d to Boron Sulfide

Downloaded by CORNELL UNIV on May 17, 2017 | http://pubs.acs.org Publication Date: June 1, 1968 | doi: 10.1021/ba-1968-0072.ch015

JIMMIE

G . E D W A R D S and

PAUL

W.

GILLES

University of Kansas, Lawrence, K a n .

The decomposition of metathioboric acid, HBS (s), to produce boron sesquisulfide, B S (glass), and the vaporization of the latter have been studied mass spectrometrically in the temperature range 50° to 665°C. At temperatures below 100°C. relative intensities, appearance potentials, and shut ter effects of the ions from partly decomposed HBS have been measured. Six metastable ionic reactions have been found, and other ionic fragmentations have been studied. The vapor species below 100°C. are H S(g), (HBS ) (g), H BS (g), and H B S (g). The existence of gaseous boron sulfides having molecular weights over 800 has been con firmed by studies of the vaporization of B S at temperatures over 250°C. Many new ionic species, including polymers of BS2+, are reported. Variations of ionic intensity ratios with temperature indicate that several neutral molecules exist in the vapor of B S . 2

2

3

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2

2

2

2 3

5

3

3

ecent investigations of the v a p o r i z a t i o n of c o n d e n s e d m a t e r i a l s i n the H S - B S system h a v e r e v e a l e d a v a r i e t y of gaseous m o l e c u l e s . T h e i m p o r t a n t c o n d e n s e d phases i n this system are H B S a n d B S . T h e i n f r a r e d spectra of H B S ( s ) a n d of the gaseous p r o d u c t s of reactions between H S ( g ) and B S ( g l a s s ) have been investigated b y Greene (3, 4). H e a t t r i b u t e d some of the b a n d s to ( H B S ) ( g ) a n d some to a H B S ( H B S ) m i x t u r e . S o m m e r , W a l s h , a n d W h i t e (12) e x a m i n e d the mass s p e c t r u m of v a p o r f r o m a m i x t u r e of Z n S a n d b o r o n at 700° to 8 0 0 ° C , b u t f o u n d n o i o n m o r e massive t h a n B S .

Τ)

2

2

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2

2

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2

3

+

211

Margrave; Mass Spectrometry in Inorganic Chemistry Advances in Chemistry; American Chemical Society: Washington, DC, 1968.

2

212

MASS S P E C T R O M E T R Y IN INORGANIC C H E M I S T R Y

T h r e e n e w series of h i g h m o l e c u l a r w e i g h t m o l e c u l e s w e r e d i s c o v e r e d b y G r e e n e a n d G i l l e s ( 5 , 6) i n t h e i r mass s p e c t r o m e t r i c investigations of the v a p o r i z a t i o n of b o r o n sulfide p r e p a r e d b y d e c o m p o s i t i o n of H B S ( s ) . 2

Series I ions c o n t a i n e d b o r o n a n d s u l f u r o n l y ; Series I I c o n t a i n e d b o r o n , sulfur, a n d a t h i r d element or r a d i c a l , p r o b a b l y s i l i c o n ; a n d Series I I I c o n t a i n e d b o r o n , sulfur, a n d o x y g e n .

T h e d e c o m p o s i t i o n of H B S ( s ) 2

was s t u d i e d mass s p e c t r o m e t r i c a l l y b y E d w a r d s , W i e d e m e i e r , a n d G i l l e s ( 2 ) ; t h e y d i s c o v e r e d the v a p o r to b e c o m p o s e d of H S ( g ) , 2

(HBS ) (g), 2

3

H B S ( g ) , and H B S ( g ) . 3

3

2

2

5

T h e p u r p o s e of this p a p e r is to r e p o r t n e w mass s p e c t r o m e t r i c results o n this system a n d to b r i n g these together w i t h p r e v i o u s results to r e a c h Downloaded by CORNELL UNIV on May 17, 2017 | http://pubs.acs.org Publication Date: June 1, 1968 | doi: 10.1021/ba-1968-0072.ch015

conclusions a b o u t the n u m b e r a n d n a t u r e of the n e u t r a l m o l e c u l e s i n the vapor, about their dependence on temperature a n d sample composition, a n d a b o u t t h e i r i o n i c f r a g m e n t a t i o n reactions. Experimental Samples. P r e p a r a t i o n of H B S a n d B S was b y the m e t h o d u s e d b y G r e e n e a n d G i l l e s ( 6 ) a n d is i l l u s t r a t e d b y the f o l l o w i n g c h e m i c a l e q u a tions, 2

2

3

4 H S ( g ) + 2B(s) = 2 H B S ( g ) + 3 H ( g ) ,

(1)

HBS (g) = H B S ( s ) ,

(2)

2

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2

2

2 H B S ( s ) = B S ( glass) + H S ( g ) . 2

2

8

2

(3)

R e a c t i o n 1 was a c c o m p l i s h e d at 600° to 8 0 0 ° C . i n a 9 6 % s i l i c a glass t u b e ; the H S was c a r r i e d over Β i n a stream of H to restrict the d e c o m p o s i t i o n reaction, 2

2

xH S(g)=xH (g) 2

2

+S (g). x

(4)

R e a c t i o n 2 o c c u r r e d i n the cooler regions of the p r e p a r a t i o n t u b e . T h e boron i n Reaction 1 was a sample w i t h an isotopic composition of 9 3 % B and 7% B obtained from Oak Ridge National Laboratory. H y d r o g e n sulfide was o b t a i n e d f r o m c o m m e r c i a l c y l i n d e r s of the c o m p r e s s e d m a t e r i a l a n d was d r i e d before use. A p p a r a t u s . A d e t a i l e d i n v e s t i g a t i o n of the d e c o m p o s i t i o n R e a c t i o n 3 c o n s t i t u t e d a m a j o r p a r t of this study. T h e r e a c t i o n w a s p e r f o r m e d i n the stainless steel mass spectrometer v a c u u m enclosure at r e s i d u a l gas p r e s sures b e l o w 10" torr. T h e mass spectrometer was a N u c l i d e , 12 i n c h r a d i u s , 60° m a g n e t i c sector, h i g h t e m p e r a t u r e mass spectrometer. T h e v a c u u m enclosure consisted of three regions separately p u m p e d b y m e r c u r y diffusion p u m p s w ith l i q u i d n i t r o g e n t r a p s : — ( 1 ) T h e m o l e c u l a r source r e g i o n c o n t a i n e d the s a m p l e i n a g r a p h i t e K n u d s e n c e l l ; ( 2 ) T h e i o n i z a t i o n r e g i o n c o n t a i n e d the i o n source a n d i o n b e a m f o r m i n g plates; ( 3 ) T h e a n a l y z e r a n d c o l l e c t o r r e g i o n was crossed b y the a n a l y z i n g m a g n e t i c field, a n d c o n t a i n e d the i o n c o l l e c t o r a n d e l e c t r o n m u l t i p l i e r . R e g i o n s 2 a n d 3 w e r e separated b y the final i o n f o c u s s i n g slit. 1 0

n

6

y


15.

EDWARDS A N D GILLES

Boron

213

Sulfides

R e g i o n s 1 a n d 2 w e r e s e p a r a t e d b y a n e x t e r n a l l y m o v e a b l e slit w h i c h c o u l d b e u s e d to i n t e r r u p t or s c a n the m o l e c u l a r b e a m b e f o r e i t e n t e r e d the i o n i z a t i o n r e g i o n . W i t h this b e a m shutter closed, the m o l e c u l a r source a n d the i o n i z a t i o n source w e r e effectively i s o l a t e d . Pressures i n the three regions w e r e m e a s u r e d w i t h hot c a t h o d e i o n i z a t i o n gages.


T h e sample was contained i n a graphite K n u d s e n cell w h i c h h a d b e e n outgassed in vacuo at 1 5 0 0 ° C . T h e c e l l c o n t a i n e d a n effusion orifice w h i c h w a s 0.4 m m . i n d i a m e t e r a n d 6.3 m m . l o n g , a n d was h e a t e d b y r a d i a t i o n f r o m t u n g s t e n resistance filaments. T e m p e r a t u r e u n i f o r m i t y w a s a c h i e v e d b y use of t a n t a l u m r a d i a t i o n shields. T e m p e r a t u r e s w e r e measu r e d w i t h a P t , P t - 1 0 % R h t h e r m o c o u p l e , the h o t j u n c t i o n of w h i c h was i n s e r t e d i n t o a w e l l i n the b o t t o m of the c r u c i b l e . P r o c e d u r e . T h e i n c o n g r u e n t v a p o r i z a t i o n of a s a m p l e of about 0.5 grams of H B S was s t u d i e d i n d e t a i l at p r o g r e s s i v e l y i n c r e a s i n g t e m p e r a tures u p to 6 6 5 ° C . T h i s s a m p l e was the one u s e d i n a n e a r l i e r s t u d y ( 2 ) . T h e s a m p l e w a s h e a t e d to the t e m p e r a t u r e d e s i r e d for a g i v e n s t u d y , a n d was m a i n t a i n e d constant at this t e m p e r a t u r e w h i l e measurements w e r e b e i n g m a d e . W h i l e observations w e r e not b e i n g m a d e — i . e . , overn i g h t or o n w e e k e n d s , the s a m p l e was not h e a t e d a n d w a s k e p t u n d e r h i g h v a c u u m at r o o m t e m p e r a t u r e . W h e n m a i n t e n a n c e of the mass spectrometer r e q u i r e d s h u t d o w n of the v a c u u m system, d r y h e l i u m was i n t r o d u c e d , b u t the s a m p l e was not exposed to the atmosphere. 2

I n i t i a l studies w e r e m a d e at temperatures f r o m 5 5 ° to 95 ° C . f o r a b o u t three m o n t h s , f r o m 7 0 ° to 80 ° C . for a b o u t one m o n t h , a n d f r o m 80° to 9 0 ° C . for t w o weeks. A t this p o i n t the c r u c i b l e w i t h the s a m p l e was r e m o v e d f r o m the mass spectrometer for the first t i m e a n d stored for f o u r m o n t h s i n a p l a s t i c v i a l i n a desiccator. T h e final measurements w e r e m a d e at h i g h e r c r u c i b l e temperatures. Studies w e r e p e r f o r m e d d u r i n g a o n e - m o n t h p e r i o d at 25 different t e m peratures f r o m 100° to 6 6 5 ° C . T h e s a m p l e w a s s t u d i e d f o r s e v e r a l h o u r s at a g i v e n t e m p e r a t u r e , a n d t h e n the t e m p e r a t u r e w a s i n c r e a s e d b y 10° to 4 0 ° C . for a n e w s t u d y . A s i n the i n i t i a l studies, the s a m p l e was h e a t e d o n l y w h i l e observations w e r e b e i n g m a d e ; b e t w e e n experiments the s a m p l e w a s often c o o l e d to r o o m t e m p e r a t u r e . T h e c r u c i b l e w i t h the s a m p l e was w e i g h e d i m m e d i a t e l y b e f o r e i n t r o d u c t i o n i n t o or after r e m o v a l f r o m the mass spectrometer. I o n i c i n t e n s i ties w e r e m e a s u r e d as f u n c t i o n s of m a g n e t i c field strength, i o n accelera t i n g p o t e n t i a l , c r u c i b l e t e m p e r a t u r e , e n e r g y of i o n i z i n g electrons, a n d p o s i t i o n of the b e a m shutter. I n a d d i t i o n , the m o n o t o n i e m a n n e r i n w h i c h the t e m p e r a t u r e was v a r i e d a l l o w e d d e d u c t i o n s a b o u t the d e p e n d e n c e of intensities o n the degree of s a m p l e d e c o m p o s i t i o n . T h e studies o f i n t e n s i t y as a f u n c t i o n o f m a g n e t i c field s t r e n g t h a n d i o n a c c e l e r a t i n g v o l t a g e y i e l d e d s i m p l e scans of the mass s p e c t r u m , the mass to charge r a t i o , m/e, of a g i v e n i o n b e i n g d e t e r m i n e d b y its p o s i t i o n i n the mass s p e c t r u m . I n t e n s i t y of a n i o n as a f u n c t i o n of i o n i z i n g e l e c t r o n e n e r g y y i e l d e d the i o n i z a t i o n efficiency c u r v e , f r o m w h i c h the a p p e a r ance p o t e n t i a l , AP, w a s d e t e r m i n e d b y the v a n i s h i n g c u r r e n t m e t h o d . T h e e n e r g y axis w a s c a l i b r a t e d f r o m the AP of H g . I n t e n s i t y as a f u n c t i o n of s h u t t e r p o s i t i o n gave shutter profiles a n d t o t a l shutter effects—i.e., p e r c e n t a g e i n t e n s i t y decrease u p o n c l o s i n g the shutter. W h e n the shutter +


214


effect was less t h a n 100, it was also m e a s u r e d o n isotope peaks to establ i s h the extent to w h i c h p e r m a n e n t b a c k g r o u n d gases c o n t r i b u t e d to the intensity. M e a s u r e m e n t s of i o n i n t e n s i t y as a f u n c t i o n of t e m p e r a t u r e y i e l d t e m p e r a t u r e coefficients for the p a r e n t molecules i f the c o m p o s i t i o n of the c o n d e n s e d phase i n the K n u d s e n c e l l is constant. Studies of i n t e n s i t y ratios as functions of t e m p e r a t u r e y i e l d e d i n f o r m a t i o n about i o n i c d e c o m p o s i t i o n i n the i o n source of the mass spectrometer. N o r m a l ions w e r e i d e n t i f i e d f r o m t h e i r m/e values. T h e i d e n t i f i c a tions w e r e c o n f i r m e d b y c o m p a r i n g the o b s e r v e d intensities w i t h the t h e o r e t i c a l i n t e n s i t y d i s t r i b u t i o n c a l c u l a t e d f r o m the p r o p o s e d c h e m i c a l f o r m u l a a n d the k n o w n isotopic compositions of the elements. T h e c o n firmation p r o c e d u r e is i l l u s t r a t e d i n F i g u r e 1 w i t h the use of d a t a p r e sented b y G r e e n e a n d G i l l e s ( 6 ) for the i o n B S i . T h e s o l i d l i n e o n the r i g h t connects the o b s e r v e d intensities for the b a n d of peaks w h i c h w a s p r o p o s e d to represent B S i c o n t a i n i n g n a t u r a l b o r o n , a n d the one o n the left is for the same b a n d c o n t a i n i n g 9 3 % B - e n r i c h e d b o r o n . T h e d a s h e d lines represent i s o t o p i c i n t e n s i t y d i s t r i b u t i o n s c a l c u l a t e d f r o m the i o n i c f o r m u l a s s h o w n a n d the k n o w n isotopic contents of the samples. T h e excellent agreement for the f o r m u l a B S identifies the i o n . T h e s l i g h t disagreement at l o w m/e values for the ions w i t h n a t u r a l b o r o n arose because of o v e r l a p w i t h a w e a k b a n d of Series I I I ions w i t h the formula B S i 0 . W h e n i s o t o p i c ions of t w o or m o r e species o v e r l a p p e d i n the mass s p e c t r u m , the c o n t r i b u t i o n s w e r e s e p a r a t e d b y a s t r i p p i n g t e c h n i q u e . T h e first p e a k i n the b a n d w a s a t t r i b u t e d to a single species c o m p o s e d o n l y of the lightest isotope of e a c h element. C o n t r i b u t i o n s f r o m this species at h i g h e r m/e values w e r e t h e n c a l c u l a t e d a n d s u b t r a c t e d f r o m t h e o b s e r v e d intensities to o b t a i n intensities c a u s e d b y the r e m a i n i n g species. T h i s process was r e p e a t e d u n t i l a l l c o n t r i b u t i o n s w e r e separated. I n scans of the mass s p e c t r u m the shapes of the peaks a n d the r e gions b e t w e e n peaks w e r e s t u d i e d closely to d i s c o v e r the presence of " m e t a s t a b l e " ions. T h e s e result f r o m i o n i c fragmentations of the t y p e ,


8

8

4

4

+

+

1 0

8

9

3

] 4

+

+

A -» B + +

C.,

+

(5)

o c c u r r i n g after the i o n A has entered the e l e c t r i c a c c e l e r a t i o n field, b u t b e f o r e i t enters the a n a l y z i n g m a g n e t i c field. H i p p i e , F o x , a n d C o n d o n ( 7 ) h a v e s h o w n that i f the f r a g m e n t a t i o n occurs after a c c e l e r a t i o n is c o m p l e t e t h e n the m/e v a l u e , m * , at w h i c h the metastable i o n appears i n the mass s p e c t r u m is r e l a t e d to the m / e values of A a n d B b y +

+

+

m*=m Vm . B

(6)

A

M e t a s t a b l e ions w e r e d i s t i n g u i s h e d f r o m others i n the mass s p e c t r u m b y t h e i r diffuse a p p e a r a n c e a n d b y the fact that t h e y m i g h t a p p e a r at n o n i n t e g r a l m/e values. T o i d e n t i f y the ions A a n d B i n R e a c t i o n 5 for a p a r t i c u l a r metastable i o n , the o b s e r v e d a p p a r e n t mass m * w a s c o m p a r e d w i t h values c a l c u l a t e d f r o m E q u a t i o n 6 for a l l possible d e c o m p o s i tions a m o n g the ions i n the mass s p e c t r u m . It was r e q u i r e d t h a t E q u a t i o n 6 b e satisfied, that the ions A a n d B h a v e r e l a t i v e l y h i g h intensities, a n d that the n e u t r a l p r o d u c t C b e a reasonable c h e m i c a l species. +

+

+

+


15.

EDWARDS

A N D CILLES

Boron

215

Sulfides

C A L C U L A T E D AND OBSERVED INTENSITIES


"

528

530

1

1

532

1

1

534

1

536

1

1

538

1

Γ

1

540

542

M A S S NO.

Figure 1. Observed and Calculated Intensity Distributions for Identification °f ^8^n - On the Left—Ions Containing Boron Enriched in B. On the Right —Ions Containing Natural Boron. Solid Lines—Observed Relative Intensities, Broken Lines—Calculated Relative Intensities for the Following Formulas. 1—B S , 2—B S , 3—B S , 4—B S , 5—BjjS , 6—B S , 7—B S +

8

10

+

n

2

+

16

5

+

lft

8

+

U

+

ls

n

+

12

17

+

n

Results The H B S

2

w a s o b t a i n e d f r o m R e a c t i o n s 1 a n d 2 as w h i t e n e e d l e

crystals a m o n g some g r a y a n d less c l e a r l y c r y s t a l l i n e p r o d u c t . T h e mass spectra o b s e r v e d at a l l temperatures i n these experiments consisted o f a l a r g e n u m b e r o f w e l l r e s o l v e d peaks g r o u p e d i n b a n d s .

Some


bands

216

M A S S S P E C T R O M E T R Y IN INORGANIC C H E M I S T R Y

consisted of ions w i t h a s i n g l e s t o i c h i o m e t r y b u t different i s o t o p i c c o m positions.

M o r e c o m p l e x b a n d s r e s u l t e d f r o m o v e r l a p of t w o or m o r e

simple bands. E v e n t h o u g h the same s a m p l e was u s e d for a l l measurements, the results are g r o u p e d a c c o r d i n g to the t e m p e r a t u r e of the c r u c i b l e . I n the l o w e s t r e g i o n t h e v a p o r i z i n g substance w a s H B S ( s ) a n d i n the h i g h e s t 2

r e g i o n , p r e d o m i n a n t l y B S ( g l ) . S e p a r a t i n g these regions is a t r a n s i t i o n 2

3

one e x t e n d i n g f r o m 100° to 2 5 0 ° C . Table I.

Ions Observed from 6 0 ° to 100°C. D u r i n g Vaporization of H B S


1 0

Mass of Prominent Peak 32 33 34 64 10 42 43 74 75 76 106 107 108 109 84 85 116 117 148 149 150 182 126 158 190 191 192 193 224 225

No. of H 0 1 2 0 0 0 1 0 1 2 0 1 2 3 0 1 0 1 0 1 2 2 0 0 0 1 2 3 2 3

Relative Intensity Atoms/Molecule 85°C, 70 e.v. S Β 0 0 0 0 1 1 1 1 ι ι 1 ι ι 1 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3

1 1 1 2 0 1 1 2 2 2 3 3 3 3 2 2 3 3 4 4 4 5 3 4 5 5 5 5 6 6

8.4 8.4 20 8.0 2.2 1.3 0.41 18 16 20 2.5 3.0 1.7 1.3 2.4 6.1 9.4 17 3.1 13 98 0.68 1.0 0.70 0.34 3.3 3.3 0.10 1.8 100

2

Appearance Potential (e.v. ± 0.3)

Shutter Effect (%) at 60°C.

15.3 15.9 10.2 19 23.1 25.8 24.3 16.4 12.4 11.8 16.1 11.6 14.0 9.9 22.1 16.6 13.1 13.1 13.0 11.4 10.5 8.9 13.0 15.0 15.2 11.2 11.5

11 11 10 58 76 65 47 76 62 67 74 65 77 21 87 84 89 89 92 94 92 50 93 92 93 93 93 91 98 95

12.3 9.3


15.


Vaporization of H B S

Boron

2

217

Sulfides

Below 100°C.

T h e s e studies h a v e b e e n r e

p o r t e d b y E d w a r d s , W i e d e m e i e r , a n d G i l l e s ( 2 ) . T h e mass loss o f t h e i r s a m p l e d u r i n g t h e investigations b e l o w 1 0 0 ° C . w a s 1 9 . 7 % o f t h e i n i t i a l mass. I f H S w e r e t h e o n l y v o l a t i l e substance;—i.e., i f t h e d e c o m p o s i t i o n 2

o c c u r r e d o n l y b y R e a c t i o n 3, t h e mass loss o n c o m p l e t e

decomposition

w o u l d b e 2 2 . 8 % ; because other gases w e r e o b s e r v e d , t h e extent of c o n v e r s i o n w a s less t h a n 8 6 % . T h i r t y ions w h i c h a p p e a r e d i n the mass s p e c t r u m at temperatures f r o m 6 0 ° to 100 ° C . are l i s t e d i n T a b l e I., c o l u m n s 2-4. I n c o l u m n s 1 a n d 5 are l i s t e d t h e m/e values a n d r e l a t i v e intensities o b s e r v e d i n a t y p i c a l i n v e s t i g a t i o n at 8 5 ° C .

T h e intensities g i v e n w e r e o b t a i n e d as i n t e n s i t y


decreases p r o d u c e d b y c l o s i n g t h e b e a m shutter, a n d are t h e s u m of a l l i s o t o p i c intensities for each i o n r e l a t i v e to ( H B S ) 2

3

+

w h i c h w a s t a k e n to

b e 100. A p p e a r a n c e potentials w e r e m e a s u r e d f o r a l l ions w h i c h w e r e suffi c i e n t l y intense, a n d are r e p o r t e d i n c o l u m n 6 of T a b l e I. T h e i n d i c a t e d u n c e r t a i n t y of ± 0 . 3 e.v. i n these values w a s d e d u c e d b y m e a s u r i n g some of t h e values several times. T h e shutter effect for t h e ions v a r i e d w i t h t i m e . W h e n t h e H B S ( s ) 2

w a s p l a c e d i n t h e mass spectrometer, t h e shutter effects of most ions w e r e i n i t i a l l y a p p r o x i m a t e l y 100. H o w e v e r , after several hours of v a p o r i z a t i o n the s h u t t e r effects decreased

n o t i c e a b l y , a n d this decrease

t h r o u g h o u t the experiments b e l o w 1 0 0 ° C .

continued

T h e shutter effect for e a c h of

the ions, g i v e n i n c o l u m n 7 o f T a b l e I., w a s o b t a i n e d e a r l y i n t h e d e c o m p o s i t i o n b u t after the shutter effects h a d decreased

considerably.

The

temperature was 60°C. Six metastable ions w e r e d i s c o v e r e d i n t h e studies b e l o w 1 0 0 ° C . T h e r e l a t i v e intensities o f these w e r e less t h a n 0.2 w i t h t h e i n t e n s i t y o f (HBS ) 2

3

+

t a k e n as 100. T h e metastable d e c o m p o s i t i o n reactions w h i c h

w e r e d e d u c e d are l i s t e d i n T a b l e I I i n w h i c h t h e first t w o c o l u m n s g i v e a p p a r e n t a n d c a l c u l a t e d m/e values. T h e next three sets of three c o l u m n s i d e n t i f y t h e reactions. A p p e a r a n c e potentials of f o u r metastable ions w e r e m e a s u r e d a n d are l i s t e d i n C o l u m n 14 of T a b l e I I ; t h e intensities of t h e other t w o i d e n t i f i e d metastable ions w e r e too l o w to o b t a i n d e p e n d a b l e A P values. I n c o l u m n s 12 a n d 13 of T a b l e I I are l i s t e d A P values of t h e p r o p o s e d parents a n d fragments f o r a l l six metastable reactions. T h r e e different groups of t w o metastable reactions are d e s i g n a t e d b y t h e letters A., B , a n d C i n t h e last c o l u m n o f T a b l e I I . F o r g r o u p A the metastable i o n a n d t h e p r o p o s e d f r a g m e n t h a v e t h e same A P ; the A P values f o r g r o u p Β w e r e n o t d e t e r m i n e d .

F o r g r o u p C t h e A P o f the

metastable i o n is l o w e r t h a n that of the p r o p o s e d f r a g m e n t , a n o c c u r r e n c e for w h i c h n o satisfactory e x p l a n a t i o n r e a d i l y appears.


218


O t h e r m e t a s t a b l e ions w e r e c a r e f u l l y sought, b u t n o t f o u n d . A s p e c i a l s e a r c h w h i c h p r o v e d to b e u n s u c c e s s f u l w a s d e v o t e d to the reactions, (HBS )

3

(HBS )

3

2

2

H B S 2

2

5

+

+

-+ H B S

+

-» HB S

2

3

3

-> H B S

3

5

5

+

+ HS,

+

+ H S,

(8)

2

+ HBS

+

(7)

(9)

2

Q u a n t i t a t i v e i n f o r m a t i o n about i o n i c f r a g m e n t a t i o n processes c a n b e o b t a i n e d b y c o n s i d e r a t i o n o f shutter effects. A s i m p l e d e r i v a t i o n y i e l d s


the e q u a t i o n

(10) Σ'< i = l i n w h i c h S j is t h e shutter effect of i o n j to w h o s e intensity η i o n i c f r a g m e n t a t i o n processes c o n t r i b u t e , a n d S i Is

t

n

e

shutter effect of i o n i , one

of t h e η ions w h i c h f r a g m e n t to y i e l d i o n j . T h e p a r t c o n t r i b u t e d b y i o n i to t h e i n t e n s i t y o f i o n j is s y m b o l i z e d b y i i . T h u s , w h e n t h e shutter effects are k n o w n , one has a r e l a t i o n s h i p a m o n g t h e c o n t r i b u t i o n s f r o m v a r i o u s fragmentations to a g i v e n i o n i c i n t e n s i t y . E q u a t i o n 10 is e s p e c i a l l y u s e f u l w h e n η = 2, because o n e obtains the r a t i o of intensities f r o m t h e t w o fragmentations. S u c h is s u r e l y t h e case f o r B S , since there are o n l y t w o n e u t r a l m o l e c u l e s w i t h t w o or 2

2

+

m o r e b o r o n atoms, H B S 2

Table II.

2

3

a n d ( H B S ) . F o r this case, η i n E q u a t i o n 10 2

3

Metastable Decompositions f r o m H No. Atoms/Molecule

Apparent 38.5 46.8 48.5 71.3 89.7 100.0

± 0.08 38.50 ±0.1 46.77 ± 0.08 48.49 ± 0.1 71.27 ± 0.2 89.66 ± 0.08 99.95

BS

2

below

100°C.

Appearance Potential (e.v. ± 0.3)

Mass Calculated

1 0

Parent H B S

Fragment H B S

Neutral H B S

Parent

Fragment

Metastable

2 2 1 2 1 2 2 3 2 2 3 3

2 0 1 1 0 2

0 1 0 1 2 1

10.5 13.1 11.4 11.5 10.5 9.3

11.8 16.4 16.6 13.1 13.1 10.5

11.8 13.5 14.9 ND ND 10.4

4 3 4 5 4 6

1 1 2 2 2 2

2 2 2 3 3 4

1 1 0 1 0 1

2 1 2 2 1 2

Identification Group

b b

A C C B B A

Group A . Identification established by mass, intensity, and ΑΡ. Group B. Identification indicated by mass and intensity. Group C . Identification indicated by mass and intensity, but contraindicated by A P . Not Detected.

a

ft


15.

EDWARDS AND

Boron

GILLES

219

Sulfides

is 2, i o n j is B S , i o n 1 is H B S \ a n d i o n 2 is ( H B S ) 2

2

+

2

2

n

2

3

+

. W i t h shutter

effects f r o m T a b l e I w e h a v e 87 = w h i c h reduces to I /h

501! + 9 5 I

2

sults f r o m fragmentations of ( H B S ) 2

2

3

+

(ii)

— 4.5. T h u s , f o u r to five times as m u c h B S

2

l a t i o n for B S

2

y i e l d s I /h 2

=

+

3

as f r o m H B S 2

2

r )

+

2

re

+

. A similar calcu

6.5, a n d the result is the same for H B S 2

3

+

,

because its shutter effect is the same. F o r o n l y one other i o n i n T a b l e I I is i t clear that η — 2. T h i s is H B S 2

2

+

, b u t a p p l i c a t i o n of E q u a t i o n 10 to

this i o n is c o m p l i c a t e d b y the fact that i s o t o p i c ions of B S , w i t h a d i f 2


ferent shutter effect a p p e a r at the same m/e

2

+

value a n d must be taken

i n t o account. V a p o r i z a t i o n F r o m 1 0 0 ° t o 2 5 0 ° C . Scans of the mass s p e c t r u m w e r e successively p e r f o r m e d i n the t r a n s i t i o n r e g i o n at 100°, 110°, 130°, 155°, 170°, 190°, 2 1 5 ° , a n d 2 4 0 ° C .

T h e y w e r e u s u a l l y t a k e n i n the d e c r e a s i n g

mass d i r e c t i o n a n d r e q u i r e d s e v e r a l hours e a c h . T h e s e scans w e r e c h a r a c t e r i z e d b y c h a n g i n g r e l a t i v e intensities of ions a n d b y the absence of h i g h m o l e c u l a r w e i g h t ions. A l l ions present b e l o w 1 0 0 ° C . w e r e o b s e r v e d i n these scans.

The

intensities for most ions v a r i e d i r r e g u l a r l y w i t h t e m p e r a t u r e , e v e n to the extent t h a t some intensities sometimes w e r e less t h a n i n the p r e c e d i n g scan at l o w e r temperature. T h e g e n e r a l t r e n d for the intensities of a l l the ions except H S 2

was to a t t a i n a m a x i m u m at a b o u t 1 5 5 ° C ,

+

to decrease w i t h i n c r e a s i n g t e m p e r a t u r e . T h e i n t e n s i t y of H S 2

+

then

also d i d

n o t v a r y s m o o t h l y , b u t a l w a y s i n c r e a s e d w i t h i n c r e a s i n g temperatures. T w o ions n o t o b s e r v e d b e l o w 1 0 0 ° C . w e r e f o u n d i n this t e m p e r a t u r e range. T h e i o n S

8

+

scans a b o v e 1 5 0 ° C .

was present i n a l l scans, a n d H B S 2

T h e i n t e n s i t y of S

t i v e to t h a t of ( H B S ) 2

3

+

8

+

4

9

+

was f o u n d i n t h e

w a s a l w a y s less t h a n 1 0 % r e l a

, a n d its v a r i a t i o n w i t h t e m p e r a t u r e w a s s i m i l a r

to t h a t of the m a j o r i t y of the ions. T h e i n t e n s i t y of H B S 2

1 5 5 ° C . i t was less t h a n 0 . 3 % that of ( H B S ) 2

3

+

4

9

+

was l o w ; at

. It i n c r e a s e d m o n o t o n i c a l l y

w i t h t e m p e r a t u r e a n d at 2 4 0 ° C . was 2.5 times as l a r g e as at 1 5 5 ° C .

No

n e w metastable t r a n s i t i o n was o b s e r v e d , a n d n o b o r o n sulfide i o n l a r g e r t h a n B S r , was f o u n d i n this t e m p e r a t u r e r a n g e . 3

+

F e w measurements r e q u i r i n g constant i o n i c intensities at a g i v e n t e m p e r a t u r e w e r e p e r f o r m e d because

of r a p i d s a m p l e

decomposition.

T h e a p p e a r a n c e p o t e n t i a l of H B S > at 2 0 2 ° C . w a s f o u n d to be 8.9 e.v. 2

±

2

r

+

0.3 e.v. Vaporization Above 250°C.

Scans of the mass s p e c t r u m w e r e m a d e

at 2 6 5 ° , 2 7 5 ° , 3 0 0 ° , 3 3 0 ° , 3 6 0 ° , 3 7 0 ° , 4 0 0 ° , 4 3 0 ° , 4 6 5 ° , 4 9 0 ° , 5 1 0 ° , 5 4 0 ° , 565°, 590°, 615°, 640°, and 665°C.

T h e h i g h m o l e c u l a r w e i g h t ions d i s

covered b y Greene and Gilles (6)

w e r e o b s e r v e d , a n d m a n y n e w ions


220


c o n t a i n i n g no h y d r o g e n w e r e d i s c o v e r e d . h y d r o g e n - c o n t a i n i n g ions,—e.g., H S 2

+

A few low molecular weight,

and H B S

2

r e m a i n e d i n the mass

+

s p e c t r u m at these temperatures, a n d t h e i r intensities r e l a t i v e to those of the h i g h m o l e c u l a r w e i g h t ions w e r e v e r y h i g h . T h e Series I ions w i t h f o r m u l a s s i m p l e r t h a n B S 3

significant intensities at 2 6 5 ° C .

G

+

w e r e present w i t h

a n d r e m a i n e d i n the s p e c t r u m at the

highest t e m p e r a t u r e . T h r e e l a r g e r Series I ions, B S i , B S i , a n d B S $ 7

were

observed

H B S 2

4

9

265°C.

+

at 2 6 5 ° C ,

, w a s s t i l l present.

a n d one

2

+

8

4

+

8

larger, hydrogen-containing

1(

+

ion,

N o Series I I or I I I i o n w a s detectable

at

A f e w ions c o n t a i n i n g five a n d six borons w e r e first d e t e c t e d at

275°C. A t 3 0 0 ° C . the mass s p e c t r u m was m u c h r i c h e r i n ions; B S i Downloaded by CORNELL UNIV on May 17, 2017 | http://pubs.acs.org Publication Date: June 1, 1968 | doi: 10.1021/ba-1968-0072.ch015

8

5

ap

+

p e a r e d a l o n g w i t h B S i , B S i , B S i , B S i \ a n d several others. 7

4

+

7

3

+

8

a d d i t i o n , t w o Series I I I ions, B S i 0 8

5

+

2

+

6

In

2

a n d B S i 0 , b e c a m e detectable. 8

3

+

A s the t e m p e r a t u r e was i n c r e a s e d a b o v e 3 0 0 ° C . the mass s p e c t r u m became very rich.

M a n y Series I a n d I I I ions w e r e f o u n d , a n d a b o v e

4 0 0 ° C . the Series I I ions a p p e a r e d .

A t about 3 5 0 ° C . ions w i t h as m a n y

as ten b o r o n atoms a c h i e v e d detectable intensities. I n a l l three series of ions the intensities of the l o w m o l e c u l a r w e i g h t ions v a r i e d w i t h t e m p e r a t u r e differently t h a n d i d the intensities of the h i g h m o l e c u l a r w e i g h t ions. T h e intensities of most Series I ions w i t h less t h a n 250 i n c r e a s e d m o n o t o n i c a l l y w i t h t e m p e r a t u r e , b u t f o r

m/e

h e a v i e r ions the intensities r e a c h e d a m a x i m u m at a b o u t 400° to 5 0 0 ° C . t h e n decreased.

A t temperatures s l i g h t l y a b o v e 2 5 0 ° C . a n d also a b o v e

6 0 0 ° C . the intensities of l o w m/e

ions w e r e greater t h a n those for the

h e a v i e r ions, b u t i n the r e g i o n 300° to 6 0 0 ° C , the h e a v i e r ions w e r e m o r e intense t h a n the l i g h t e r ions except for H S , H B S , S , a n d B S . +

2

Intensities of Series I I ions w i t h m/e w i t h increasing temperature.

+

2

2

+

2

b e l o w a b o u t 450

Ions w i t h h i g h m/e

3

+

increased

values h a d intensities

t h a t r e a c h e d a m a x i m u m b e t w e e n 550° to 6 5 0 ° C , t h e n decreased increasing temperature.

Series I I I ions w i t h m/e

increased i n intensity w i t h increasing temperature.

less t h a n a b o u t

with 300

T h e others r e a c h e d

a m a x i m u m i n t e n s i t y b e t w e e n 400° a n d 6 0 0 ° C . t h e n decreased w i t h t e m p e r a t u r e . A l t h o u g h m a n y of the n e w ions w e r e present i n the s p e c t r u m over o n l y short t e m p e r a t u r e ranges, B S i 8

6

+

was o b s e r v e d

i n a l l scans

above 250°C. I n F i g u r e 2 the intensities of the b o r o n - s u l f u r ions r e l a t i v e to that of B S i o as 100 w h i c h w e r e o b s e r v e d i n the scan at 4 9 0 ° C . are s h o w n 8

+

graphically. formula B S n

T h e l o c a t i o n of e a c h n u m b e r represents a n i o n w i t h the m

+

, i n w h i c h η a n d m are, r e s p e c t i v e l y , the o r d i n a t e a n d

abscissa of the l o c a t i o n . T h e t w o d a s h e d lines o n the g r a p h c o n n e c t l o c a tions of the i o n i c p o l y m e r s of B S 2

3

a n d B S , respectively. 2

M o s t ions f a l l

w i t h i n the r e g i o n enclosed b y these lines. N o t s h o w n are ions c o n t a i n i n g


15.


Boron

221

Sulfides

o n l y o n e element, a l t h o u g h B as w e l l as a l l i o n i c s u l f u r p o l y m e r s u p to +

S

8

+

w e r e observed.

A r e l a t i v e i n t e n s i t y o f zero means t h a t t h e i o n w a s

not o b s e r v e d at 4 9 0 ° C . b u t w a s o b s e r v e d i n o n e o r m o r e o f t h e other scans; a G represents a n i o n o b s e r v e d b y G r e e n e a n d G i l l e s ( β ) b u t not o b s e r v e d i n this w o r k ; a n d u n d e r l i n i n g indicates a n i o n not o b s e r v e d b y them. —ι

1

1

/

y

rp^i

1 y

G

/ β>' 1.9 5.3 3.7 12


2.7 4.6 ^52 £5^22

48

y

.I 2.2

.9 .4

a2x|.l

-y

7.2/23

τ ο

.8

^

±'

y

^

140 180 J00^

58 JL\" s-'

5.1 ' 82

3.5 6.6^

13 . 9 ^

1.6 2.6

3.3 3.5 .9

. 3 y%\ ' . 4 I

_J 2

I 3

I 4

I 5

I 6

L 7

8

9

10

II

12

13

14

15

16

17

18

19

20 21

SULFUR

Figure 2. Relative Intensities of Series I Boron Sulfide Ions at 490°C. The numbers of boron and sulfur atoms in the ion are given as ordinate and abscissa. Intensity of B S equals 100. Underlining indicates an ion not observed by Greene and Gilles, and a G represents each ion observed by them hut not observed in this work 8

+

16

R e l a t i v e intensities o f the Series I ions o b s e r v e d a t t h e same t e m p e r a t u r e , 4 9 0 ° C . , are also r e p r e s e n t e d o n a s c h e m a t i c mass s p e c t r u m i n F i g u r e 3. T h e o r d i n a t e gives o n a l o g a r i t h m i c scale the p e r c e n t a g e i n tensity r e l a t i v e to that o f B S 8

H î

+

. T h e abscissa identifies the i o n , first b y

the n u m b e r o f b o r o n atoms, t h e n b y the n u m b e r o f s u l f u r atoms; thus i t is n o t c o n t i n u o u s i n m/e. I n F i g u r e s 4 a n d 5 are s h o w n , r e s p e c t i v e l y , the Series I I o r s i l i c o n c o n t a i n i n g ions w h i c h w e r e o b s e r v e d i n the scan at a h i g h e r t e m p e r a t u r e , 640° C . , a n d t h e i r r e l a t i v e intensities o n a s c h e m a t i c mass s p e c t r u m o f the same t y p e as i n F i g u r e 3. F i g u r e s 6 a n d 7 illustrate i n the same w a y the Series I I I , or b o r o n - s u l f u r - o x y g e n ions, a n d t h e i r r e l a t i v e intensities i n the scan at 565 ° C . C o m p o s i t i o n v a r i a t i o n s i n t h e samples p r e v e n t e d d i r e c t use o f i n tensity vs. t e m p e r a t u r e d a t a to o b t a i n t h e r m o d y n a m i c q u a n t i t i e s , b u t



222

MASS

SULFUR Ο123 BORON

1

Figure 3.

23

6 Q

3 ^

4 5

2

7

S P E C T R O M E T R Y IN

89|

67

9

89

0

4

3

I0||,2

5

,0,,

I2|3|4

6

INORGANIC

, 2 , 3

*I5|6

7

I 3 , 4

8

CHEMISTRY

I5|6

,6|7

»8|9 0 2

9

10

Logarithms of Relative Intensities of Series I Boron Sulfide Ions at 490°C. Intensity of B S ; Equals 100 8

ir

i n f o r m a t i o n o n f r a g m e n t a t i o n processes c a n b e o b t a i n e d .

C o n s i d e r the

ionic fragmentation reaction A ->B +C +

(12)

+

I f o n l y one m o l e c u l a r source y i e l d s A , a n d i f R e a c t i o n 12 is the o n l y +

source of B \ t h e n the i n t e n s i t y ratio Z( A ) / J ( B ) is i n d e p e n d e n t of s a m +

ple composition. either i o n A

+

+

H o w e v e r , i f m o r e t h a n one m o l e c u l a r source exists for

or i o n B , t h e n the v a l u e of the i n t e n s i t y r a t i o w i l l d e p e n d +

on sample composition and temperature. I n F i g u r e 8 l o g a r i t h m s of three i n t e n s i t y ratios, Z ( B S i r > ) / Z ( B S i 8

7(B S 7

1 2

+

)/7(B S 8

1 4

+

) , and Z ( B S 8

the inverse t e m p e r a t u r e . p e r a t u r e are t y p i c a l of temperatures Z(B S 8

1 2

+

below

)/Z(B S 8

1 4

+

)

1 2

+

)/Z(B Si 8

4

+

+

8

( î

+

),

) are p l o t t e d as functions of

T h e variations of these three ratios w i t h t e m those f o u n d for other ions.

750°K.

(1/T

and Z ( B S 7

l 2

+

=

1.33

)/Z(B S 8

1 4

+

)

X

10"*)

A t Knudsen cell intensity ratios

w e r e effectively i n d e p e n d -

ent of t e m p e r a t u r e a n d c o m p o s i t i o n , a n d , therefore, b o t h ions w h o s e i n tensities a p p e a r i n the r a t i o p r o b a b l y h a d a single m o l e c u l a r precursor. A b o v e this t e m p e r a t u r e a n e w source arose for the i o n w h o s e i n t e n s i t y appears i n the n u m e r a t o r i n e a c h of these t w o ratios as i n d i c a t e d b y the i n c r e a s i n g v a l u e of the i n t e n s i t y ratio w i t h i n c r e a s i n g t e m p e r a t u r e .


15.

EDWARDS

A N D GILLES ~ι

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SULFUR

Figure 4. Relative Intensities of Series II Boron Sulfide Ions at 640°C. Each ion contains one silicon atom. The numbers of boron and sulfur atoms are given as ordinate and abscissa. Intensity of B.S Si equals 100. Underlining indicates an ion not observed by Greene and Gilles, and a G represents each ion observed by them but not observed in this work +

8

SULFUR 3 BORON I

Figure 5.

9

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I0|| 5

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Loganthms of Relative Intensities of Series II Boron Sulfide Ions at 640°C. Intensity of B^S Si Equals 100 8

+


I920 10

Suicide

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MASS S P E C T R O M E T R Y

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CHEMISTRY

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High Molecular Weight Boron Sulfides - Advances in Chemistry (ACS

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