Sterically hindered tetrylenes based on new 1,10-phenanthroline-containing diols: initiators for ε-caprolactone polymerization

• Published in: Russian chemical bulletin Vol. 68; no. 2; pp. 380 - 388
• Main Authors: Mankaev, B. N., Zaitsev, K. V., Zaitseva, G. S., Churakov, A. V., Egorov, M. P., Karlov, S. S.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-02-2019; Springer Nature B.V
• Subjects: ATOMS; CARBON 13; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Coordination numbers; CRESOLS; Crystal structure; Crystals; Diols; Full Articles; GERMANIUM; GLYCOLS; HYDROGEN 1; Initiators; Inorganic Chemistry; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; KETONES; LIGANDS; MONOCRYSTALS; NMR; NUCLEAR MAGNETIC RESONANCE; Organic Chemistry; PHENANTHROLINES; POLYMERIZATION; POTASSIUM HYDROXIDES; Single crystals; SOLUTIONS; Synthesis; Tin; TIN 119; X-RAY DIFFRACTION; YIELDS; germylenes; stannylenes; tin; tetrylenes; germanium; poly-ε-caprolactone; ring-opening polymerization
• ISSN: 1066-5285; 1573-9171
• DOI: 10.1007/s11172-019-2396-4

Previously unknown tetradentate ONNO-type ligands
1
–
5
(4,7-di(4-R´-phenoxy)-2,9- di(HOCR
2
CH)-1,10-phenanthrolines (R´ = Me, R–R = –(CH
2
)
5
– (
1
), R = Me (
2
), R–R = 2,2-adamantylene (
3
); R´ = But, R–R = –(CH
2
)
5
– (
4
), R = Me (
5
)) were synthesized by sequential treatment of 2,9-dimethyl-4,7-di(4-R´-phenoxy)-1,10-phenanthrolines
6
(R´ = Me) and
7
(R´ = Bu
t
) with excess LDA and appropriate dialkyl ketone. The structure of compound
4
was determined by single-crystal X-ray diffraction. Previously uncharacterized phenanthroline
6
was synthesized by the treatment of 4,7-dichloro-2,9-dimethyl-1,10-phenanthroline with excess
p
-cresol in the presence of KOH. The reaction of compounds
1
–
5
with one equivalent of Lappert´s germylene or stannylene, M[N(SiMe
3
)
2
]
2
(M = Ge, Sn), gave the corresponding germylenes
8
–
12
(M = Ge, R´ = Me, R–R = –(CH
2
)
5
– (
8
), R = Me (
9
), R–R = 2,2-adamantylene (
10
), R´ = Bu
t
, R
2
= –(CH
2
)
5
– (
11
), R = Me (
12
)) and stannylenes
13
–
17
(M = Sn, R´ = Me, R–R = –(CH
2
)
5
– (
13
), R = Me (
14
), R–R = 2,2-adamantylene (
15
), R´ = Bu
t
, R–R = –(CH
2
)
5
– (
16
), R
2
= Me (
17
)) in satisfactory yields. According to
1
H,
13
C, and
119
Sn NMR data, the synthesized stannylenes are monomeric in solution, and the tin atom has a coordination number of 4. In the series of the compounds under consideration, stannylene
16
proved to be the most active initiator for e-caprolactone polymerization, whereas the germylenes were shown to be inactive in this process.