Synthesis and Characterization of Group 14 Dialkylmetal Chalcogenones RN2M=-E [RN = CH(SiMe3)C9H6N-8 or CPh(SiMe3)C5H4N-2; M = Ge or Sn; E = S, Se, or Te]

Article abstract of DOI:10.1021/om9906159

Treatment of group 14 metal dialkyl MR^N₂ (M = Ge or Sn) with elemental chalcogens (sulfur, selenium, or tellurium) in THF afforded the corresponding chalcogenones R^N₂M=E [R^N = CPh(SiMe₃)C₅H₄N-2; M = Ge; E =S (4), Se (5), Te (6); M = Sn; E = S (7), Se (8); R^N = CH(SiMe₃)C₉H₆N-8, M = Sn; E = Se (10), Te (11)]. In contrast, a sulfido-bridged dimer [R^N₂Sn(μ-S)]2 (9) was obtained from similar reaction of SnR^N₂ [R^N = CH(SiMe₃)C₉H₆N-8] with elemental sulfur. These chalcogenones have been characterized by elemental analysis, ¹H, ¹³C, ¹¹⁹Sn, ⁷⁷Se, and ¹²⁵Te NMR, and mass spectroscopy, X-ray structure of 5, 8, 9, 10, and 11 have been determined. It was revealed that compounds 5, 8, 10, and 11 consist of a terminal metal-chalcogen bond with the ligands R^N acting in a C,N-chelate fashion, except for 9, which is a sulfido-bridged dimer.

Full text of DOI:10.1021/om9906159

296
Organometallics 2000, 19, 296-303
Syn th esis a n d Ch a r a cter iza tion of Gr ou p 14
Dia lk ylm eta l Ch a lcogen on es RN MdE [RN )
2
CH(SiMe3)C9H6N-8 or CP h (SiMe3)C5H4N-2; M ) Ge or Sn ;
E ) S, Se, or Te]
Wing-Por Leung,* Wai-Him Kwok, Zhong-Yuan Zhou, and Thomas C. W. Mak
Department of Chemistry, The Chinese University of Hong Kong, Shatin,
New Territories, Hong Kong, China
Received August 2, 1999
Treatment of group 14 metal dialkyl MRN (M ) Ge or Sn) with elemental chalcogens
2
(sulfur, selenium, or tellurium) in THF afforded the corresponding chalcogenones RN2MdE
[RN ) CPh(SiMe3)C5H4N-2; M ) Ge; E dS (4), Se (5), Te (6); M ) Sn; E ) S (7), Se (8); RN
) CH(SiMe3)C9H6N-8, M ) Sn; E ) Se (10), Te (11)]. In contrast, a sulfido-bridged dimer
[RN2Sn(µ-S)]2 (9) was obtained from similar reaction of SnRN [RN ) CH(SiMe3)C9H6N-8]
2
with elemental sulfur. These chalcogenones have been characterized by elemental analysis,
1H, 13C, 119Sn, 77Se, and 125Te NMR, and mass spectroscopy. X-ray structure of 5, 8, 9, 10,
and 11 have been determined. It was revealed that compounds 5, 8, 10, and 11 consist of a
terminal metal-chalcogen bond with the ligands RN acting in a C,N-chelate fashion, except
for 9, which is a sulfido-bridged dimer.
In tr od u ction
heavier congeners, thermally stable dialkylstannane-
tellurone [R2SndTe] in particular, are scarcely found.
Compounds featuring a double bond between heavier
main-group G14-16 elements were considered to be
unstable due to the weak pπ-pπ bonding.1 Neverthe-
less, thioketone analogues comprised of group 14 and
group 16 congeners such as silanethione (SidS),2,3
silaneselone (SidSe),2 germanethione (GedS),3-5 ger-
maneselone (GedSe),6,7 stannanethione (SndS), and
stannaneselone (SndSe) have been isolated in the past
few years.8-11 These compounds were either base-
stabilized2,3 or stabilized by using a sterically hindered
protecting group as in [Tip(Tbt)GedE] [E ) S and Se;
Tbt ) 2,4,6-tris(bistrimethylsilyl)methyl]phenyl; Tip )
2,4,6-triisopropylmethylphenyl].3,5,7,8,11 Tin(IV) and ger-
manium(IV) complexes with terminal sulfido and se-
lenido ligands supported by porphyrin type or macro-
cyclic octamethyldibenzotetraaza[14]annulene ligands
(Me8taa) have also been reported recently.6,9,10 The
Dialkylstannanethiones such as [But SndS] and [Ph2-
2
SndS] are known to exist as transient species which
readily oligomerize to dimers and trimers.12 Monomeric
diarylstannanethione and -selone with sterically hin-
dered groups have only been detected as intermediates
and trapped by various reagents to form cycloaddition
products. The stannanethione [Tip(Tbt)SndS]8 isolated
was found to dimerize readily at temperatures above
90 °C, and the structures of [{Tip(Tbt)Sn(µ-E)}2] (E )
S, Se)8,11 have been reported.
In our previous communication, we have reported the
synthesis and characterization of dialkylstannanechal-
cogenones [(RN)2SndE] [RN ) CH(SiMe3)C9H6N-8; E )
Se, Te].13 A year later, Meller and co-workers reported
a base-stabilized dialkylgermanechalcogenone [{C-
(SiMe3)2C5H4N-2}2GedE].14 In this paper, we report the
full details of the synthesis, structures, and multi-
nuclear NMR spectroscopic data of dialkylgermane- and
dialkylstannanechalcogenones bearing N-functionalized
alkyl ligands [CH(SiMe3)C9H6N-8]- (R1) and [CPh-
(SiMe3)C5H4N-2]- (R2).
* Corresponding author. Fax: (852)26035057. E-mail: kevinleung@
cuhk.edu.hk.
(1) Barrau, J .; Escudie´, J .; Satge´, J . Chem. Rev. 1990, 90, 283.
(2) Arya, P.; Boyer, J .; Carre´, F.; Corriu, R.; Lanneau, G.; Lapasset,
J .; Perrot, M.; Prion, C. Angew. Chem., Int. Ed. Engl. 1989, 28, 1016.
(3) Suzuki, H.; Tokitoh, N.; Nagase, S.; Okazaki, R. J . Am. Chem.
Soc. 1994, 116, 11578.
(4) (a) Veith, M.; Becker, S.; Huch, V. Angew. Chem., Int. Ed. Engl.
1989, 28, 1237. (b) Veith, M.; Detemple, A.; Huch, H. Chem. Ber. 1991,
124, 1135.
(5) Tokitoh, N.; Matsumoto, T.; Manmaru, K.; Okazaki, R. J . Am.
Chem. Soc. 1993, 115, 8855.
Resu lts a n d Discu ssion
Syn th esis of Dia lk ylger m a n e- a n d Dia lk ylsta n -
n a n ech a lcogen on es. The reactions of germanium(II)
and tin(II) dialkyls MR2 (R ) R1 or R2) with elemental
chalcogens E (E ) S, Se, and Te) are summarized in
(6) Hutcha, M. C.; Parkin, G. J . Chem. Soc., Chem. Commun. 1994,
1351.
(7) Matsusumoto, Y.; Tokitoh, N.; Okazaki, R. Angew. Chem., Int.
Ed. Engl. 1994, 33, 2316.
(8) Tokitoh, N.; Saito, M.; Okazaki, R. J . Am. Chem. Soc. 1993, 115,
2065.
(9) Guilard, R.; Ratti, C.; Barbe, J .-M.; Dubois, D.; Kadish, K. M.
Inorg. Chem. 1991, 30, 1557.
(10) Kuchta, M. C.; Parkin, G. J . Am. Chem. Soc. 1994, 116, 8372.
(11) Matsuhashi, Y.; Tokitoh, N.; Okazaki, R.; Goto, M. Organome-
tallics 1993, 12, 2573.
(12) (a) Puff, H.; Gattermayer, R.; Hundt, R.; Zimmer, R. Angew.
Chem., Int. Ed. Engl. 1977, 16, 547. (b) Schumann, H. Z. Anorg. Allg.
Chem. 1967, 354, 192.
(13) Leung, W.-P.; Kwok, W.-H.; Weng, L.-H.; Law, L. T. C.; Zhou,
Z.-Y.; Mak, T. C. W. J . Chem. Soc., Chem. Commun. 1996, 505.
(14) Ossig, G.; Meller, A.; Bro¨nneke, C.; Mu¨ller, O.; Scha¨fer, M.;
Herst-Trmer, R. Organometallics 1997, 16, 2116.
10.1021/om9906159 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 01/06/2000

Group 14 Dialkylmetal Chalcogenones
Organometallics, Vol. 19, No. 3, 2000 297
Ta ble 1. UV-Vis Absor p tion Da ta of Com p ou n d s 5,
Sch em e 1
7, 8, 9, 10, a n d 11 in THF
compound
[{CPh(SiMe3)C5H4N-2}2GedSe] (5) 294 (sh, 1910), 372 (1330)
[{CPh(SiMe3)C5H4N-2}2SndS] (7) 354 (5510)
λ )
max/nm (ꢀ/dm3 mol-1 cm-1
[{CPh(SiMe3)C5H4N-2}2SndSe] (8) 324 (14750), 366 (sh, 7320)
[{CH(SiMe3)C9H6N-8}2Sn(µ-S)]2 (9) 338 (16410), 412 (sh, 1230)
[{CH(SiMe3)C9H6N-8}2SndSe] (10) 310 (5920), 340 (sh, 5780),
414 (sh, 850)
[{CH(SiMe3)C9H6N-8}2SndTe] (11) 344 (8100), 416 (sh, 820)
tion of metal amides [M{N(SiMe3)2}2] (M ) Ge, Sn) with
chalcogens yielded the appropriate metal(IV) oxidation
products [M{N(SiMe3)2}2(µ-E)]n (E ) S, Se, Te).16 It was
found that the heavier chalcogen congeners are less
stable, as shown by the behavior of the Sn-Te com-
pound, which is thermally and particularly photochemi-
cally unstable, as it gradually decomposes to the tin
amide and tellurium metal.15 The present method
provides a direct synthetic route from germylene and
stannylene via oxidative addition to germane- and
stannanechalcogenones. The thermal stability of com-
pounds 4-8 is attributable to the steric crowding of the
substituted R-carbon in ligands (R1) and (R2), N-coor-
dination, and the quinolyl and pyridyl coordination.
Attempted reaction of Pb(II) compound Pb(R1)2 with
Se and Te powder has led to the formation of black
precipitates, suggesting that the cleavage of Pb-C
bonds immediately occurred.
Spectr oscopic P r oper ties of Ch alcogen on es. Most
of the chalcogenones prepared are less lipophilic than
their parent compounds. They showed lower solubility
toward toluene and ether and are soluble only in THF,
except for compound 4, which is soluble only in CHCl3.
The UV-vis spectral data of the metal chalcogenones
are summarized in Table 1. The colors of compounds
4-6 [from white (4), through pale yellow (5), to orange
(6)], compounds 9-11 [from pale yellow (9), through
yellow-orange (10), to red (11)], and compounds 7 and
8 [from white (7) to yellow (8)] show changes with
increasing atomic number of the chalcogen. These color
trends are probably due to n f π* transitions (transfer
of lone-pair from E to a vacant metal-centered d orbital).
Similar color trends have been reported for complexes
[M{(NSiMe3)2}2(µ-E)]n (M ) Ge, Sn; E ) S, Se, Te).16
Mass spectra of compounds 4, 5, and 8-10 all showed
the presence of the parent peaks [M]+, suggesting that
compounds 4, 5, and 8-10 are monomeric in vapor
phase. However, the mass spectrum of 9 did not show
a peak at 1160 due to the parent peak [M]+ of the
dimerized species 9, but a peak at 580 was found which
was assignable to [M/2]+, suggesting that compound 9
exists as a monomeric species in vapor phase.
Scheme 1. Treating germanium(II) dialkyl [Ge(R2)2] (1)
with elemental chalcogens in THF afforded the corre-
sponding thermally stable dialkylgermanethione (4),
-selone (5), and -tellurone (6) were obtained, respec-
tively. The reaction between 1 and tellurium powder
was carried out in the absence of light, as compound 6
was found to be light-sensitive and turns black on
exposure to light. Similar reactions of tin(II) dialkyl [Sn-
(R2)2] (2) with sulfur and selenium gave corresponding
thermally stable dialkylstannanethione (7) and -selone
(8). The reaction of tellurium powder with 2 gave a
thermally unstable product, which decomposed to form
tellurium powder at temperatures exceeding -30 °C.
This result suggests that the Sn-Te interaction in
[(R2)2SndTe] is weaker than the corresponding Ge-Te
interaction in [(R2)2GedTe] (6). Indeed, terminal tellu-
rido derivatives are rare for other elements due to their
lower bond energy. This is also due to the fact that the
ability of the main group elements to take part in
multiple bonding is reduced for the heavier congener.
The π-bond energy associated with the SndS bond has
been calculated to be considerably lower than the
corresponding values for CdS, SidS, and GedS.11 The
first example of a terminal tellurido complex of a
transition metal, namely [W(PMe3)4(Te)2], has been
reported.15 More recently, bis[(2-pyridyl)bis(trimeth-
ylsilyl)methyl-C,N]germanethione, -selone, and -tellu-
rone have also been structurally characterized.14
The reaction of [Sn(R1)2] (3) with stoichiometric
amounts of elemental selenium and tellurium in THF
afforded the corresponding thermally stable dialkyl-
stannaneselone (10) and -tellurone (11) in good yields.
These thermally stable chalcogenones have been iso-
lated as THF or toluene solvates. In contrast, similar
reaction of [Sn(R1)2] with sulfur afforded compound 9,
which was found to be a sulfido-bridged dimer, as
confirmed by X-ray structural analysis. The structure
of 9 is similar to that of [(Tip)(Tbt)Sn(µ-S)]2, which was
dimerized from the thermally unstable monomer [(Tip)-
(Tbt)SndS)]. To our knowledge, compound 11 is the first
example of a compound having a terminal SndTe bond
to be unequivocally characterized from spectroscopic and
crystallographic data. Related work on the direct reac-
The 1H NMR spectra of 4-8 showed a similar pattern
and displayed one set of signals due to the alkyl ligand
R2. The characteristic tin-proton coupling constants
(2J Sn-H) of the methine protons due to alkyl ligands R1
were observed in the 1H NMR spectra of compounds
2
9-11. The values of J Sn-H lie in the range 52.1-58.1
Hz, which are significantly small. The chemical shifts
of 9-11 of methine protons (δ 1.02-1.64) are compa-
rable to the value of δ 1.16 in the parent tin(II)
compound [Sn(R1)2] (3), indicating the ambiguous oxida-
(16) Hitchcock, P. B.; J asim, H. A.; Lappert, M. F.; Leung, W.-P.;
Rai, A. K.; Taylor, R. E. Polyhedron 1991, 10, 1203.
(15) Rabinovich, D.; Parkin, G. J . Am. Chem. Soc. 1991, 113, 9421.

298 Organometallics, Vol. 19, No. 3, 2000
Leung et al.
Ta ble 2. 119Sn , 77Se, a n d 125Te NMR Sp ectr oscop ic Da ta for Som e Meta l-Ch a lcogen on es
compound
119Sn NMRa δ, ppm
77Se NMRb δ, ppm
-734.80
125Te NMRc δ, ppm
[(R2)2GedSe] (5)
1097.08
-100.48
-111.55
[{R1(R1)Sn(µ-S)}2] (9)
[(R1)2SndSe] (10)
1J
Se: 2951 Hz
1J
1J
Sn: 2818 Hz
Sn: 2966 Hz
119Sn-77
77Se-117
77Se-119
[(R1)2SndTe] (11)
-350.34
1J
-2030.63
Te: 7808 Hz
Se: 2684 Hz
1J
1J
Sn: 7641 Hz
Sn: 7808 Hz
119Sn-125
125Te-117
125Te-119
[(R2)2SndS] (7)
[(R2)2SndSe] (8)
-54.70
-179.18
-531.95
1J
1J
1J
Sn: 2567 Hz
Sn: 2682 Hz
119Sn-77
77Se-117
77Se-119
a
b
Recorded in THF/C6D6, referenced to external SnMe4, 186.50 MHz. Recorded in THF/C6D6, referenced to external Se2Me2, 95.41
MHz. c Recorded in THF/C6D6, referenced to external Te(S2CEt)2, 157.92 MHz.
tion state of double-bonded tin in compounds 4-8. The
13C{1H} NMR spectra of compounds 4-8 are not so
significant.
The 77Se, 119Sn, and 125Te NMR spectroscopic data of
the metal chalcogenones are shown in Table 2. The 119Sn
signals lie in the range δ -54.70 to -350.34 ppm from
S to Te. These values are comparatively different from
the value of δ 2208 for stannanethione [(Tbt)(Tip)Snd
S],8 but are comparable to the values of δ -301 and δ
F igu r e 1.
-444 (1J
) 3450 Hz) for stannanethione and
119Sn-77Se
-selone [(η4-Me8taa)SndE] (X ) S, Se), respectively.10
The singlet signals of 8, 10, and 11 display satellite
signals due to coupling of 119Sn-77Se (I ) 1/2, 7.6%) in
8 and 10 and 119Sn to 125Te (I ) 1/2, 7.1%) in 11. The
large coupling constants, J
Hz 8) and J
1
119Sn-77Se
(2951 Hz 10, 2684
1
119Sn-125Te
(7808 Hz 11) are consistent with
directly bonded terminal SndSe and SndTe moieties.
In contrast, the corresponding coupling constants for
[Sn{N(SiMe3)2}2(µ-E)]n (E ) Se, Te) are 1128 and 2700
Hz, respectively.20
The 77Se NMR spectra of 10 and 8 display a singlet
at δ -734.80 and δ -531.95, with doublet satellites due
to coupling of 77Se-117Sn (2818 Hz 10, 2567 Hz 8) and
77Se-119Sn (2966 Hz 10, 2682 Hz 8), respectively, which
are consistent with the values found in 119Sn NMR
spectra of 10 and 8. The 77Se NMR spectrum of 5
displays a singlet at δ 1097.08, which is quite different
from the value of its tin analogue of compound 8, but
comparable to the value of δ 940.6 for germaneselone
[(Tbt)(Tip)GedSe] (18).7
F igu r e 2. Crystal structure of 5 with atomic labeling
scheme.
Dialkylgermaneselone 5 and -stannaneselone 8 both
crystallize in a monoclinic C2 (No. 5) space group and
were obtained as THF solvates. The two alkyl ligands
R2 are bonded to the central metal atom in a trans C,N-
chelating fashion, and the metal centers display square
pyramidal geometry with selenium atoms occupying the
axial positions of the pyramidals. The values of N(1)-
M-N(2) angles [M ) Ge 143.8(2)°; Sn 145.9(2)°] are too
small to describe as a distorted trigonal bipyramidal
geometry. Both the structures of 5 and 8 lie on 2-fold
rotation axes, so that the other half of the structures
are identical to the original half when it is rotated along
the 2-fold axis by 180°.
Four coordination atoms make a least-squares base
plane, from which deviation of C(6), C(6a), N(1), and
N(1a) atoms in 5 and 8 are about (0.2766 and (0.2772
Å, respectively. The Ge and Sn atoms occupy the apexes
and are 1.0156 and 0.9675 Å departed from the base
plane and lie 0.0325 and 00569 Å out of the C5H4N(1,1a),
respectively. The sums of the bond angles involving the
basal ligand atoms are 317.0° and 320.6°, respectively.
The two dihedral angles between the two phenyl planes
of 5 and 8 are 11.4° and 10.9°, respectively.
The 125Te NMR spectrum of 11 displayed a singlet at
δ -2030.63 with satellites due to the coupling constants
1
1J
(7641 Hz) and J
125Te-117Sn
125Te-119Sn
(7808 Hz), respec-
tively, which are also consistent with the values found
in the 119Sn NMR spectrum of 11.
X-r a y Str u ctu r es. Compound 5 and 8 are isostruc-
tural to each. The molecular structures with the atom-
numbering schemes for compounds 5 and 8 are shown
in Figures 2 and 3, respectively. Selected bond distances
(Å) and angles (deg) of 5 and 8 are listed in Table 3.
(17) Pauling, L. The Nature of The Chemical Bond, 3rd ed.; Cornell
University Press: Ithaca, NY, 1960; p 224.
(18) Goilhman, R.; Aizenberg, M.; Shimon, L. J . W.; Milstein, D. J .
Am. Chem. Soc. 1996, 118, 10894.
(19) Leung, W.-P.; Kwok, W.-H.; Weng, L.-H.; Law, L. T. C.; Zhou,
Z.-Y.; Mak, T. C. W. J . Chem. Soc., Dalton Trans. 1997, 4301.
(20) Sheldrick G. M. In Crystallographic Computing 3: Data Col-
lection, Structure Determination, Proteins, and Databases; Sheldrick,
G. M., Kruger, C., Goddard, R., Eds.; Oxford University Press: New
York, 1985; p 175.

Group 14 Dialkylmetal Chalcogenones
Organometallics, Vol. 19, No. 3, 2000 299
packing diagram of 5 and 8, only one of the rac-isomers
is observed with configuration (R,A,R). Therefore, the
space groups of compound 5 and 8 are both chiral (C2).
Similarly, there should exist another type of crystal that
is packed by molecules with (S,C,S) configuration, and
the formation of other diastereoisomers is believed to
be unfavorable as proposed before. The X-ray structures
of 5 and 8 (Figures 2 and 3) show the molecules of 5
and 8, respectively, with (R,A,R) configuration.
Compound 9 crystallizes in a monoclinic C2/c (No. 15)
space group and is obtained as THF solvates. X-ray
crystallographic analysis established the dimeric struc-
ture of 9 (see ref 13), and selected bond distances (Å)
and bond angles (deg) are shown in Table 4. The
structure of 9 possesses an inversion center i, so that
half of the structure is centrosymmetric to the other
half. As a consequence of steric congestion around Sn,
one of the N-functionalized alkyl ligands R1 bonded to
the metal center behaves as a monodentate C-centered
ligand, while the other ligand is bonded to the tin in a
chelate fashion. The two C-centered alkyl ligands and
the two bidentate ligands are trans to each other,
respectively. The five-coordinate Sn displays a distorted
trigonal planar geometry with S(1a) and N(2) occupying
the axial positions trans to each other. The S(1a)-Sn-
(1)-N(2) angle is 168.6(1)°, though it is slightly deviated
from the value of 180° in the ideal trigonal planar
geometry. The Sn atom is 0.2911 Å departed from the
trigonal plane described by C(10), C(23), S(1). The other
trigonal plane described by C(10a), C(23a), N(2a) is
parallel to the previous trigonal plane as expected and
in staggered configuration with a twist angle of 56.7°,
58.1° and 65.2°, respectively. The atoms Sn(1), Sn(1a),
S(1), S(1a) form a four-membered ring, and this plane
is nearly orthogonal (88.5°) to the trigonal planes
described. The quinolyl plane C9H6N(1) is nearly paral-
lel to the other quinolyl plane C9H6N(2), with a dihedral
angle of 9.0°, which suggests the possibility of intramo-
lecular π-π interaction between these two planes, while
the planes C9H6N(1) and C9H6N(2) are coplanar to the
planes of C9H6N(1a) and C9H6N(2a), respectively. The
Sn(1) and Sn(1a) atoms both lie 0.6842 Å out of the
chelated quinolyl planes C9H6N(2) and C9H6N(2a),
respectively.
F igu r e 3. Crystal structure of 8 with atomic labeling
scheme.
In compound 5, the Ge-Se bond distance is 2.426(2)
Å and is relatively longer than the Ge-Se distances in
[(Tbt)(Tip)GedSe]7 [2.180(2) Å] and [(η4-Me8taa)Ged
Se]6 [2.247(1) Å], but slightly shorter than the distance
in [{C(SiMe3)2C5H4N-2}2GedSe]14 [2.2472(7) Å]. Sur-
prisingly, the Ge-Se bond distance in 5 is slightly
longer than the sum of the covalent radii of Ge (1.22 Å)
and Se (1.16 Å). This suggests the resonance structure
B in Figure 1 contributes more than the resonance
structure A. The average Ge-C and Ge-N distances
are 2.283 and 2.379 Å, respectively, which are larger
than the values of 2.214 and 2.299 Å in the parent
compound 1 unexpectedly. The C-Ge-C angle of 5
[111.1(2)°] is close to the value of 111.3(2)° in 1. The
average bite distance C‚‚‚N and the bite angle C-Ge-N
are 2.332 Å and 60.0°, respectively, which are compa-
rable to the values of 2.350 Å and 64.2° in 1.
In compound 8, the Sn-Se bond distance is 2.418(1)
Å, which is slightly longer than the value of 2.394(1) Å
of the related compound [(η4-Me8taa)SndSe].10 The
calculated values of SndSe and Sn-Se are 2.37 and 2.57
Å.17 The Sn-Se bond distance lies between the calcu-
lated values of Sn-Se single and double bonds and is
quite different from the Ge-Se bonding in 5, suggesting
the type of Sn-Se bonding in 8 lies between the
resonance structure A and B in Figure 1. The average
Sn-C and Sn-N distances are 2.240 and 2.358 Å,
respectively, which are significantly shorter than the
values of 2.331 and 2.432 Å in the parent compound 2.
The decrease in these distances can be explained by the
consequence of the change in oxidation state from Sn-
(II) to Sn(IV). The contrary findings in 5 may partly be
explained by the difference in the covalent and ionic
nature of tin and germanium. Also the steric congestion
around Ge, which has a smaller size than Sn, also
accounts for this contrast. The average bite distance C‚
‚‚N and bite angle C-Sn-N are 2.370 Å and 62.0°,
respectively, which are comparable to the values of
2.383 Å and 60.0° in 2.
The average Sn-S distance of 2.47 Å in 9 is slightly
longer than that [2.44 Å (av)] in [(Tbt)(Mes)Sn(µ-S)]2.18
The Sn-C(10) and Sn-C(23) distances of 2.198 and
2.203 Å in 9 are shorter than the value of 2.263 Å (av)
in the corresponding tin(II) compound 3. Due to the ring
strain in the five-membered ring in the chelated ligand
R1, the bite distance C(23)‚‚‚N(2) (2.805 Å) is slightly
shorter than the related distance C(10)‚‚‚N(1) (2.796 Å)
of the C-centered ligand R1.
It is noteworthy that the stereochemistry for the
molecule of 9 is quite complicated. The structure deter-
mination of 9 shows one of the diastereoisomers with a
configuration of (S,C,S) at Sn(1) and (R,A,R) at Sn(1a);
therefore, the space group for this molecule in the X-ray
structure analysis is C2/c, which possesses a center of
symmetry. In the unit cell lattice packing diagram of
9, only one type of diastereoisomer with configuration
(S,C,S, R,A,R) is observed. It is possible that the
formation of other diastereoisomers such as (S,C,R,
S,A,R) is not favorable due to the steric hindrance of
Since the germanium and tin atoms adopt distorted
square pyramidal geometry and are chiral respectively
in 5 and 8, they should have eight possible diastereo-
isomers with the combination of the two chiral R-car-
bons in the alkyl ligand R2. From the unit cell lattice

300 Organometallics, Vol. 19, No. 3, 2000
Ta ble 3. Selected Bon d s Dista n ces (Å) a n d An gles (d eg) for Com p ou n d s 5 a n d 8
Leung et al.
M ) Ge 5
M ) Sn 8
Bond Distances
M ) Ge 5
M ) Sn 8
M-Se(1)
M-C(1)
M-C(1a)
C(1)-C(2)
2.426(2)
2.283(5)
2.283(5)
1.417(7)
2.418(1)
2.240(6)
2.240(6)
1.520(9)
M-N(1)
2.379(5)
2.379(5)
1.936(5)
1.369(5)
2.358(6)
2.358(6)
1.928(6)
1.344(7)
M-N(1a)
Si(1)-C(1)
C(2)-N(1)
Bond Angles
Se(1)-M-N(1)
N(1)-M-C(1)
C(1)-M-N(1a)
C(1)-M-C(1a)
C(1)-C(2)-N(1)
108.1(1)
60.0(2)
98.5(2)
111.1(2)
113.7(4)
107.0(1)
62.0(2)
98.3(2)
112.5(3)
111.6(6)
Se(1)-M-C(1)
N(1)-M-N(1a)
Se(1)-M-C(1a)
M-C(1)-C(2)
M-N(1)-C(2)
124.5(1)
143.8(2)
124.5(1)
94.4(2)
123.7(1)
145.9(2)
123.7(1)
93.2(3)
91.6(3)
93.1(4)
Ta ble 4. Selected Bon d s Dista n ces (Å) a n d An gles
(d eg) for Com p ou n d 9
and 11 are shown in Table 5. Similar to compounds 5
and 8, the X-ray structures of 10 and 11 show the
monomeric species with two alkyl ligands R1 bonded to
the tin center in a trans C,N-chelating fashion. The five-
coordinate tin is bonded directly to the axial ligand Se
and Te at 2.398(1) and 2.618(1) Å in 10 and 11,
respectively. The center tin atoms in 10 and 11 are both
pentacoordinated, and they are better described as
distorted trigonal bipyramidal since the values of key
angles N(1)-M-N(2) of 10 and 11 are 158.0(2)° and
157.1(2)°, respectively.
The Sn-Se distance in 10 is significantly shorter than
that in the selenium-bridged dimers [{Tbt)(Tip)Sn(µ-
Se)]2 [2.57 Å (av)] and [(Mes)(Tbt)Sn(µ-Se)]2 (2.562 Å).11
The 7% reduction in bond length is consistent with
enhanced contribution of π-bonding between Sn and Se.
The Sn-Se bond distance of 10 is comparable to the
value of 2.394(1) Å in the related stannaneselone [(η4-
Me8Taa)SndSe].16 The Sn-Te bond distance of 2.618(1)
Å in 11 is smaller than the sum of the covalent radii of
Sn (1.40 Å) and Te (1.37 Å). The average Sn-C and
Sn-N distances in 10 (2.187 and 2.376 Å) and 11 (2.174
and 2.382 Å) are shorter than the values of 2.263 and
2.506 Å, respectively. The decrease in the Sn-C and
Sn-N distances is a consequence of the change in
oxidation state from Sn(II) to Sn(IV). The average bite
distance C‚‚‚N and the bite angles C-Sn-N of alkyl
ligands R1 in 10 (2.798 Å, 75.5°) and 11 (2.785 Å, 75.2°)
are quite different.
Bond Distances
Sn(1)-S(1)
Sn(1)-C(10)
Sn(1)-S(1a)
Sn(1)-N(2)
Si(2)-C(23)
C(8)-C(9)
2.420(3)
2.198(4)
2.528(2)
2.483(3)
1.895(5)
1.418(8)
1.467(6)
1.464(5)
Sn(1a)-S(1a)
Sn(1)-C(23)
Sn(1a)-S(1)
Si(1)-C(10)
C(10)-C(8)
C(9)-N(1)
2.420(3)
2.203(6)
2.528(2)
1.886(5)
1.518(4)
1.330(7)
1.424(7)
1.343(8)
C(23)-C(22)
C(21)-C(22)
C(21)-C(23)
C(22)-N(2)
Bond Angles
S(1)-Sn(1)-N(2)
N(2)-Sn(1)-C(10)
N(2)-Sn(1)-C(23)
S(1)-Sn(1)-S(1a)
C(10)-Sn(1)-S(1a)
Sn(1)-S(1)-Sn(1a)
C(10)-C(8)-C(9)
84.4(1) S(1)-Sn(1)-C(10)
112.2(2)
124.8(1)
91.9(1) S(1)-Sn(1)-C(23)
73.0(1) C(10)-Sn(1)-C(23) 118.2(2)
89.2(1) N(2)-Sn(1)-S(1a)
168.6(1)
99.2(1) C(23)-Sn(1)-S(1a) 103.4(1)
90.8(1) Sn(1)-C(10)-C(8)
121.2(4) C(8)-C(9)-N(1)
113.4(3)
116.7(3)
Sn(1)-C(23)-C(21) 110.6(3) C(23)-C(21)-C(22) 119.6(5)
C(21)-C(22)-N(2)
116.5(4) Sn(1)-N(2)-C(22)
109.6(2)
For compounds 10 and 11, there exist two chiral
R-carbons in the alkyl ligands R1 and there are four
possible diastereoisomers. However, only the rac-
isomers with configuration (R,R) and (S,S) are observed
in the unit cell lattice packing diagram of 10 and 11.
The formation of molecules with (R,S) and (S,R) con-
figurations may be unfavorable due to the steric hin-
drance of the bulky SiMe3 groups.
F igu r e 4. Crystal structure of 10 with atomic labeling
scheme.
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were carried out
under an inert atmosphere of argon gas by standard Schlenk
techniques or in a dinitrogen glovebox. Solvents were dried
over and distilled from CaH2 (hexane) and/or Na (Et2O). Sulfur,
selenium, and tellurium powders were purchased from Aldrich
Chemicals and used without further purification. Germanium-
(II) diaklyls 1 and tin(II) dialkyls 2 and 3 were prepared
according to the literature.19 The 1H, 13C, 119Sn, 77Se, and 125Te
NMR were recorded on Bruker WM-250 or ARX-500 instru-
ments. All spectra were recorded in benzene-d6, and the
chemical shifts δ are relative to SiMe4, SnMe4, Me2Se2, and
the bulky SiMe3 groups. Moreover, in the solution state,
some of the diastereoisomers may undergo a fast
exchange process.
Compounds 10 and 11 are isostructural to each other
with different terminal chalcogens (E ) Se 10, Te 11).
Compound 10 crystallizes in a monoclinic P21/c (No. 14)
space group and with 1 equiv of THF as the solvate,
while compound 11 crystallizes in an orthorhombic
Pnna space group. The structure of 10 with atom-
numbering scheme is shown in Figure 4, and that of 11
has been reported in a previous communication.13
Selected bond distances (Å) and bond angles (deg) of 10
1
Te(S2CEt)2 for H, 13C, 119Sn, 77Se, and 125Te NMR, respectively.
Syn th esis of [{CP h (SiMe3)C5H4N-2}2GedS] (4) [(R2)2Ged
S]. A solution of [Ge(R2)2] (1) (0.225 g, 0.407 mmol) in THF

Group 14 Dialkylmetal Chalcogenones
Organometallics, Vol. 19, No. 3, 2000 301
Ta ble 5. Selected Bon d s Dista n ces (Å) a n d An gles (d eg) for Com p ou n d s 10 a n d 11
E ) Se 10
E ) Te 11
Bond Distances
E ) Se 10
E ) Te 11
Sn(1)-E
2.398(1)
2.190(6)
2.283(5)
1.436(8)
1.371(9)
1.493(8)
2.618(1)
2.174(5)
2.240(6)
1.407(7)
1.379(6)
1.502(6)
Sn(1)-N(1)
Sn(1)-N(2)
N(1)-C(9)
C(8)-C(10)
C(22)-C(21)
2.361(4)
2.390(4)
1.372(9)
1.487(8)
1.430(8)
2.382(4)
2.382(4)
1.379(6)
1.502(6)
1.407(7)
Sn(1)-C(10)
Sn(1)-C(23)
C(9)-C(8)
N(2)-C(22)
C(21)-C(23)
Bond Angles
E-Sn(1)-N(1)
99.5(1)
75.9(2)
101.5(1)
75.2(1)
E-Sn(1)-C(10)
127.3(2)
102.5(1)
91.0(2)
91.7(2)
75.1(2)
116.4(5)
107.0(3)
117.3(5)
109.7(4)
127.3(1)
101.5(1)
90.8(1)
90.8(1)
75.2(1)
117.3(4)
107.7(3)
117.3(4)
107.7(3)
N(1)-Sn(1)-C(10)
N(1)-Sn(1)-N(2)
E-Sn(1)-C(23)
E-Sn(1)-N(2)
158.0(2)
125.4(2)
107.3(2)
109.5(3)
120.2(6)
109.7(3)
119.0(6)
157.1(2)
127.3(1)
105.5(3)
108.2(3)
119.4(4)
108.2(3)
119.4(4)
C(10)-Sn(1)-N(2)
N(1)-Sn(1)-C(23)
N(2)-Sn(1)-C(23)
N(1)-C(9)-C(8)
Sn(1)-C(10)-C(8)
N(2)-C(22)-C(21)
Sn(1)-C(23)-C(21)
C(10)-Sn(1)-C(23)
Sn(1)-N(1)-C(9)
C(9)-C(8)-C(10)
Sn(1)-N(2)-C(22)
C(22)-C(21)-C(23)
(20 mL) was added slowly to the colorless solution of powdered
sulfur (13.0 mg 0.407 mmol) in THF (20 mL) at 0 °C. The
orange color of 1 faded gradually when raised to ambient
temperature. The pale yellow suspension was stirred for 18
h. The white solid was isolated, washed with pentane, and
dried in vacuo, yielding 0.218 g, 91%. Mp: 245-248 °C (dec).
EI-MS: m/z 586 [M]+, 346 [M - R2]+, 240 [R2]+. 1H NMR
(CDCl3, 250 MHz): δ 0.21 (s, SiMe3, 18H), 6.33(br, aryl H, 2H),
6.61-6.75 (m, aryl H, 6H), 7.08 (dd, J ) 8.0, 1.0 Hz, aryl H,
2H), 7.32 (ddd, J ) 7.4, 5.5, 1.0 Hz, aryl H, 2H), 7.73 (td, J )
7.7, 1.7 Hz, aryl H, 2H), 8.54 (dt, J ) 5.1, 1.3 Hz, aryl H, 2H).
13C NMR (CDCl3, 62.90 MHz): δ 0.25 (SiMe3), 61.58 (CSiMe3),
122.22, 123.63, 124.77, 126.65, 127.66, 138.47, 140.41, 145.77,
164.76 (C5H4N and C6H5).
(THF), 57.00 (CSiMe3), 67.88 (THF), 122.37, 123.24, 124.91,
125.45, 127.55, 138.17, 139.58, 145.16, 164.63 (C5H4N and
C6H5).
Syn th esis of [{CH(SiMe3)C9H6N-8}{CH(SiMe3)C9H6N-
8}Sn (µ-S)]2 (9), [(R1)(R1)Sn (µ-S)]2. To a stirring solution of
powdered sulfur (0.045 g, 1.42 mmol) in THF (20 mL) was
added dropwise a solution of [Sn(R1)2] (3) (0.77 g, 1.42 mmol)
in THF (20 mL) at 0 °C. The resultant yellow solution was
allowed to warm to room temperature and stirred for 18 h.
The solution was concentrated and kept at -20 °C, affording
a pale-yellow crystalline solid, which was washed with pentane
and dried in vacuo. Yield: 0.74 g (90%). Mp: 216-220 °C (dec).
Anal. Found: C, 54.19; H, 5.45; N, 3.86. Calcd. for C52H64N4-
Si4Sn2S2‚THF: C, 54.64; H, 5.89; N, 4.55. EI-MS: m/z 580
1
[M/2]+. H NMR (CDCl3, 250 MHz): δ -0.49 (s, SiMe3, 36H),
Syn th esis of [{CP h (SiMe3)C5H4N-2}2GedSe] (5) [(R2)2-
GedSe]. A solution of [Ge(R2)2] (1) (0.178 g, 0.322 mmol) in
THF (20 mL) was added slowly to the colorless solution of
powdered sulfur (25.4 mg 0.322 mmol) in THF (20 mL) at 0
°C. The orange color of 1 faded gradually when raised to
ambient temperature. The light yellow solution was stirred
for 18 h. It was filtered, concentrated, and stored at -30 °C,
yielding pale yellow crystals (0.111 g, 55%). Mp: 260-264 °C
(dec). Anal. Found: C, 57.19; H, 6.30; N, 2.63. Calcd for
C30H36N2Si2GeSe‚THF: C, 57.97; H, 6.30; N, 3.98. EI-MS: m/z
2
1.02 (s, J H-Sn ) 58.1 Hz, CHSi, 4H), 6.79 (d, J ) 7.1 Hz,
quinolyl H, 4H), 7.07 (t, J ) 7.7 Hz, quinolyl, 4H), 7.20-7.27
(m, quinolyl, 8H), 8.02 (dd, J ) 8.3, 1.5 Hz, quinolyl, 4H), 8.82
(dd, J ) 4.5, 1.5 Hz, quinolyl, 4H). 13C NMR (CDCl3, 62.90
MHz): δ -0.44 (s, SiMe3), 26.22 (THF), 28.64 (CSiMe3), 68.58
(THF), 121.99, 123.26, 128.42, 129.22, 130.65, 140.31, 142.78,
143.71, 147.74 (C9H6N). 119Sn NMR (THF/C6D6, 186.50 Hz,
SnMe4(ext)): δ -100.48 (s).
Syn th esis of [{CH(SiMe3)C9H6N-8}2Sn dSe] (10) [(R1)2-
Sn dSe]. To a stirring solution of powdered selenium (87.5 mg,
1.11 mmol) in THF (20 mL) was added dropwise a solution of
[Sn(R1)2] (3) (0.606 g, 1.11 mmol) in THF (20 mL) at 0 °C. The
resultant yellow solution was allowed to warm to room
temperature and stirred for 18 h. Unreacted selenium powder
was filtered off, and the filtrate was concentrated and stored
at -20 °C. Orange crystals of 10 were obtained, washed with
pentane, and dried in vacuo. Yield: 0.59 g (85%). Mp: 255-
260 °C (dec). Anal. Found: C, 51.58; H, 5.64; N, 3.93. Calcd
for C26H32Si2N2SnSe‚THF: C, 51.59; H, 5.77; N, 4.01. EI-MS:
m/z 626 [M]+, 554 [M - Se]+, 412 [M - R1]+, 340 [M - Se -
R1]+. 1H NMR (CD2Cl2, 250 MHz): δ -0.16 (s, SiMe3, 18H),
1
632 [M]+, 392 [M - R2]+. H NMR (CDCl3, 250 MHz): δ 0.23
(s, SiMe3, 18H), 1.80-1.85 (m, THF, 4H), 3.69-3.74 (m, THF,
4H), 6.62-6.66 (m, aryl H, 4H), 6.70-6.75 (m, aryl H, 4H),
7.08 (dd, J ) 8.0, 0.8 Hz, aryl H, 2H), 7.35 (ddd, J ) 7.3, 5.5,
1.0 Hz, aryl H, 2H), 7.74 (td, J ) 7.7, 1.5 Hz, aryl H, 2H), 8.54
(dt, J ) 5.5, 1.2 Hz, aryl H, 2H). 13C NMR (CDCl3, 62.90
MHz): δ 0.37 (SiMe3), 25.63 (THF), 60.02 (CSiMe3), 67.94
(THF), 122.22, 123.42, 124.76, 126.20, 127.55, 138.26, 140.02,
145.48, 164.54 (C5H4N and C6H5). 77Se NMR (THF/C6D6, 95.41
MHz, Me2Se2 (ext)): δ 1097.08 (s).
Syn th esis of [{CP h (SiMe3)C5H4N-2}2GedTe] (6) [(R2)2-
GedTe]. A solution of [Ge(R2)2] (1) (0.509 g, 0.920 mmol) in
THF (20 mL) was added slowly to the colorless solution of
powdered tellurium (0.117 g, 0.920 mmol) in THF (20 mL) in
the absence of light. The orange mixture was stirred for 18h.
The unreacted tellerium powder was filtered off, the yellowish
orange filtrate was concentrated and stored at -30 °C, yielding
yellowish orange crystals of the title compound (0.300 g, 48%).
Mp: 190-193 °C (dec). Anal. Found: C, 53.85; N, 5.81; N, 3.68.
Calcd for C30H36Si2N2GeTe‚THF: C, 54.23; H, 5.89; N, 3.72.
1H NMR (CDCl3, 250 MHz): δ 0.22 (s, SiMe3, 18H), 1.78-1.83
(m, THF, 4H), 3.67-3.72 (m, THF, 4H), 5.74 (br, aryl H, 2 H),
6.59 (br, aryl H, 4H), 6.68-6.74 (m, aryl H, 4H), 7.05 (d, J )
8.1 Hz, aryl H, 2H), 7.38 (ddd, J ) 7.3, 5.5, 1.0 Hz, aryl H,
2H), 7.74 (td, J ) 7.8, 1.5 Hz, aryl H, 2H), 8.45-8.47 (m, aryl
H, 2H). 13C NMR (CDCl3, 62.90 MHz): δ 0.72 (SiMe3), 25.57
2
1.42 (s, J H-Sn ) 56.6 Hz, CHSi, 2H), 1.77 (m, THF, 2H), 3.65
(m, THF, 2H), 7.12 (dd, J ) 7.2, 3.7 Hz, quinolyl, 2H), 7.43 (t,
J ) 7.7 Hz, quinolyl, 2H), 7.58-7.65 (m, quinolyl, 2H), 8.43
(dd, J ) 8.3, 1.6 Hz, quinolyl, 2H), 9.09 (dd, J ) 4.6, 1.6 Hz,
quinolyl, 2H). 13C NMR (CD2Cl2, 125.76 MHz): δ -0.59
(SiMe3), 26.41 (THF), 28.47 (CSiMe3), 68.58 (THF), 122.07,
123.53, 128.59, 129.60, 130.87, 140.54, 143.47, 144.13, 147.58
(C9H6N). 77Se NMR (THF/C6D6, 95.41 MHz, Me2Se2 (ext)): δ
1
1
77
119
77
117
) 2818.0 Hz).
Se- Sn
1
-734.84 (s, J
) 2941.6 Hz, J
Se- Sn
119Sn NMR (THF/C6D6, 186.50 MHz): δ -111.55 (s, J Sn-Se
)
2950.5 Hz).
Syn th esis of [{CH(SiMe3)C9H6N-8}2Sn dTe] (11) [(R1)2-
Sn dTe]. To a stirring suspension of tellerium powder (0.117
g, 0.918 mmol) in THF (20 mL) was added dropwise a solution
of [Sn(R1)2] (3) (0.502 g, 0.918 mmol) in THF (20 mL). The

302 Organometallics, Vol. 19, No. 3, 2000
Leung et al.
Ta ble 6. Selected Cr ysta llogr a p h ic a n d Da ta Collection P a r a m eter s for Com p ou n d s 5, 8, a n d 10
5
8
10
molecular formula
molecular weight
cryst size, mm
cryst syst
space group
a, Å
C
704.4
0.20 × 0.18 × 0.28
monoclinic
C2 (No. 5)
16.296(3)
30H36N2Si2GeSe.C4H8O
C35H36N2Si2SnSe
738.5
C30H40N2OSi2SnSe
698.5
0.14 × 0.16 × 0.20
0.25 × 0.25 × 0.20
monoclinic
monoclinic
C2
P21/c
14.456(3)
16.302(2)
b, Å
10.724(2)
10.7300(10)
10.700(2)
c, Å
12.071(2)
1803.05
12.0620(10)
1803.3(9)
21.915(4)
3200.2(16)
V, Å3
Z
2
2
4
density, g cm-3
abs coeff, mm-1
scan type and rate
1.298
1.360
1.808
oscillation IP photos;
60 frames in total,
1.450
2.035
oscillation IP photos;
60 frames in total,
not measured
oscillation IP photos;
30 frames in total,
φ ) -30 to 150°,
∆φ ) 6°, 8 min per frame
-70
0 e h e 19, 0 e k e 12,
-14 e l e 12
1682
1324
186
0.056
0.076
φ ) -30 to 150°,
φ ) -40 to 80°,
∆φ ) 3°, 6 min per frame
∆φ ) 2°, 12 min per frame
background level
collection range
-50
-40
-20 e h e 17, -13 e k e 13,
-17 e h e 0, -12 e k e 13,
0 e l e 15
3311
3212
-25 e l e 27
5205
3813
335
no. of unique data (Rint
no. of obsd data, n
no. of variables, F
Ra
Rw
S
weighting scheme
largest and mean ∆/σ
residual extrema in final
)
209
0.039
0.053
1.61
0.046
0.059
1.80
b
1.61
w ) [σ2|Fo| + 0.0008|Fo| ]-1
w ) [σ2|Fo| + 0.0006|Fo| ]-1
w ) [σ2|Fo| + 0.0006|Fo| ]-1
2
2
2
0.012, 0.006
0.969, 0.057
0.000, 0.000
+0.50 to -0.57
1.21 to -0.73
0.77 to -1.22
diff map, e Å-3
extinction corr
ø )0.0043, where F* )
ø )0.0039(4), where F* )
F[1 + 0.002øF2/sin(2θ)]-1/4
ø ) 0.00078(10), where F* )
F[1 + 0.002øF2/sin(2θ)]-1/4
F[1 + 0.002øF2/sin(2θ)]-1/4
resultant red solution was stirred for 18 h. Unreacted tel-
lurium powder was removed by filtration, and the filtrate was
concentrated and cooled at -20 °C. Red crystals of 11 were
obtained, washed with pentane, and dried in vacuo. Yield: 0.55
g (88%). Mp: 135-140 °C (dec). Anal. Found: C, 49.13; H, 4.94;
N, 3.88. Calcd for C26H32Si2N2SnTe‚1/2C7H8: C, 49.14; H, 5.03;
N, 3.88. EI-MS: m/z 675 [M]+, 461 [M - R1]+, 334 [M - R1 -
color of 2 deepened, and the mixture was stirred for 18 h.
Unreacted selenium powder was removed by filtration, and
the filtrate was concentrated and cooled at -20 °C. Yellow
crystals obtained were washed with pentane and dried in
vacuo. Yield: 0.147 g (60%). Mp: 260-264 °C (dec). Anal.
Found: C, 54.37; H, 5.88; N, 3.72. Calcd for C30H36N2Si2SnSe‚
THF: C, 54.41; H, 5.91; N, 3.73. EI-MS: m/z 679 [M]+, 664
[M - Me]+. 1H NMR (CDCl3, 250 MHz): δ 0.21 (s, SiMe3, 18H),
1.77-1.83 (m, THF, 4H), 3.67-3.72 (m, THF, 4H), 6.31-6.33
(m, aryl H, 4H), 6.64-6.68 (m, aryl H, 6H), 7.05 (dt, J ) 8.1,
1.0 Hz, aryl H, 2H), 7.28-7.31 (m, aryl H, 2H), 7.72 (dt, J )
7.9, 1.3 Hz, aryl H, 2H), 8.36 (dd, J ) 5.5, 1.3 Hz, aryl H, 2H).
13C NMR (CDCl3, 62.90 MHz): δ 0.25 (SiMe3), 25.54 (THF),
62.46 (CSiMe3), 67.86 (THF), 122.07, 122.94, 125.38, 125.82,
127.55, 138.52, 141.26, 146.14, 165.42 (C5H4N and C6H5). 77Se
NMR (THF/C6D6, 95.41 MHz, Se2Me2 (ext)): δ -531.95 (s,
1
Te]+. H NMR (C6D6, 250 MHz): δ 0.09 (s, SiMe3, 18H), 1.64
2
(s, J H-Sn ) 52.1 Hz, CHSi, 2H), 6,69 (dd, J ) 8.3, 4.5 Hz,
quinolyl, 2H), 6.77 (dd, J ) 6.1, 2.4 Hz, quinolyl, 2H), 6.95-
7.02 (m, quinolyl, 2H), 7.40 (dd, J ) 8.3, 1.6 Hz, quinolyl, 2H),
9.32 (dd, J ) 4.5, 1.5 Hz, quinolyl, 2H). 13C NMR (C6D6, 62.90
MHz): δ -0.67 (SiMe3), 27.82 (CSiMe3), 121.24, 122.67, 128.79,
129.29, 130.23, 139.22, 143.86, 144.55, 147.20 (C9H6N). 119Sn
NMR (THF/C6D6, 186.50 MHz, SnMe4 (ext)): δ -350.34 (s,
1J Sn-Te ) 7808.3 Hz). 125Te NMR (THF/C6D6, 157.92 MHz,
1
1
1
J
) 2566.5 Hz, J
) 2681.9 Hz). 119Sn NMR
125
119
) 7793.4 Hz,
Te- Sn
77
117
Se- Sn
77
119
Se- Sn
Te(S2CEt)2 (ext)): δ -2030.63 (s,
J
1
1
125
117
J
) 7490.2 Hz).
(THF/C6D6, 186.50 MHz, SnMe4 (ext)): δ -179.18 (s, J Sn-Se
) 2683.8 Hz).
Te- Sn
Syn th esis of [{CP h (SiMe3)C5H4N-2}2Sn dS] (7) [(R2)2Sn d
S]. A solution of [Sn(R2)2] (2) (0.675 g, 1.13 mmol) in THF (20
mL) was added slowly to the colorless solution of powdered
sulfur (36.0 mg 1.13 mmol) in THF (20 mL) at 0 °C. The yellow
color of 2 faded gradually when raised to ambient temperature.
The mixture was stirred for 18 h. It was then filtered,
concentrated, and stored at -20 °C. White solid was obtained
(0.570 g, 66%). Mp: 171-174 °C (dec). Anal. Found: C, 56.39;
H, 6.19; N, 3.97. Calcd for C30H36N2Si2SnS: C, 57.05; H, 5.75;
X-r a y Cr ysta llogr a p h y. Single crystals were sealed in 0.3
mm Lindemann glass capillaries under argon. X-ray data of
5, 8, 9, 10, and 11 were collected on a Rigaku R-AXIS II
imaging plate using graphite-monochromatized Mo KR radia-
tion (l ) 0.71073 Å) from a rotating-anode generator operating
at 50 kV and 90 mA. Crystallogaphic data for compounds 9
and 11 have been published in a previous communication.13
Crystal data for 5, 8, and 10 are summarized in Table 6.The
structures were solved by direct phase determination using
the computer program SHELXTL-PC20 on a PC 486 and
refined by full-matrix least squares with anisotropic thermal
parameters for the non-hydrogen atoms. Hydrogen atoms were
introduced in their idealized positions and included in struc-
ture factor calculations with assigned isotropic temperature
factors. Full details of the crystallographic analysis of 5, 8, 9,
10, and 11 are given in the Supporting Information.
1
N, 4.44. EI-MS: m/z 632 [M]+. H NMR (CDCl3, 250 MHz): δ
0.21 (s, SiMe3, 1H), 1.78-1.84 (m, THF, 4H), 3.68-3.74 (m,
THF, 4H), 6.31-6.35 (m, aryl H, 4H), 6.66-6.69 (m, aryl H,
6H), 7.07 (d, J ) 8 Hz, aryl H, 2H), 7.25-7.30 (m, aryl H, 2H),
7.73 (dt, J ) 7.7, 1.6 Hz, 2H), 8.39 (d, J ) 5.4 Hz, 2H). 13C
NMR (CDCl3, 62.90 MHz): δ 0.19 (SiMe3), 25.80 (THF), 64.07
(CSiMe3), 67.92 (THF), 122.05, 123.01, 125.53, 125.70, 127.72,
138.66, 141.43, 146.28, 165.33 (C5H4N and C6H5). 119Sn NMR
(THF/C6D6, 186.50 MHz, SnMe4 (ext)): δ -54.70 (s).
Syn th esis of [{CP h (SiMe3)C5H4N-2}2Sn dSe] (8) [(R2)2-
Sn dSe]. To a stirring suspension of selenium powder (0.140
g, 1.78 mmol) in THF (30 mL) was added dropwise a solution
of [Sn(R2)2] (2) (1.07 g, 1.78 mmol) in THF (30 mL). The yellow
Ack n ow led gm en t. This work was supported by the
Hong Kong Grants Council Earmarked Grant CUHK
306/94P.

Group 14 Dialkylmetal Chalcogenones
Organometallics, Vol. 19, No. 3, 2000 303
Su p p or tin g In for m a tion Ava ila ble: Details about the
X-ray crystal structures, including ORTEP diagrams and
tables of crystal data and structure refinement, atomic coor-
dinates, bond lengths and angles, and anisotropic displacement
parameters for 5, 8, and 10. This material is available free of
charge via the Internet at http://pubs.acs.org.
OM9906159