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Dinuclear neodymium and lanthanum bis(2,6‐diisopropylphenyl) phosphate complexes bearing a hydroxide ligand: catalytic activity of the Nd complex in 1,3‐diene polymerization
Author(s) -
Minyaev Mikhail E.,
Korchagina Sof'ya A.,
Tavtorkin Alexander N.,
Churakov Andrei V.,
Nifant'ev Ilya E.
Publication year - 2018
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229618006666
Subject(s) - ligand (biochemistry) , intramolecular force , medicinal chemistry , catalysis , hydrogen bond , chemistry , trigonal bipyramidal molecular geometry , phosphate , crystallography , stereochemistry , crystal structure , molecule , organic chemistry , receptor , biochemistry
The reactions of K[(2,6‐ i Pr 2 C 6 H 3 ‐O) 2 POO] either with LaCl 3 (H 2 O) 7 or with Nd(NO 3 ) 3 (H 2 O) 6 in a 3:1 molar ratio, followed by vacuum drying and recrystallization from alkanes, have led to the formation of diaquapentakis[bis(2,6‐diisopropylphenyl) phosphato]‐μ‐hydroxido‐dilanthanum hexane disolvate, [La 2 (C 24 H 34 O 4 P) 5 (OH)(H 2 O) 2 ]·2C 6 H 14 , ( 1 )·2(hexane), and tetraaquatetrakis[bis(2,6‐diisopropylphenyl) phosphato]‐μ‐hydroxido‐dineodymium bis(2,6‐diisopropylphenyl) phosphate heptane disolvate, [Nd 2 (C 24 H 34 O 4 P) 4 (OH)(H 2 O) 4 ]·2C 6 H 14 , ( 2 )·2(heptane). The compounds crystalize in the P 2 1 / n and P space groups, respectively. The diaryl‐substituted organophosphate ligand exhibits three different coordination modes, viz. κ 2 O , O ′‐terminal [in ( 1 ) and ( 2 )], κ O ‐terminal [in ( 1 )] and μ 2 ‐κ 1 O :κ 1 O ′‐bridging [in ( 1 ) and ( 2 )]. Binuclear structures ( 1 ) and ( 2 ) are similar and have the same unique Ln 2 (μ‐OH)(μ‐OPO) 2 core. The structure of ( 2 ) consists of an [Nd 2 {(2,6‐ i Pr 2 C 6 H 3 ‐O) 2 POO} 4 (OH)(H 2 O) 4 ] + cation and a [(2,6‐ i Pr 2 C 6 H 3 ‐O) 2 POO] − anion, which are bound via four intermolecular O—H…O hydrogen bonds. The molecular structure of ( 1 ) displays two O—H…O hydrogen bonds between OH/H 2 O ligands and a κ 1 O ‐terminal organophosphate ligand, which resembles, to some extent, the `free' [(2,6‐ i Pr 2 C 6 H 3 ‐O) 2 POO] − anion in ( 2 ). NMR studies have shown that the formation of ( 1 ) undoubtedly occurs due to intramolecular hydrolysis during vacuum drying of the aqueous La tris(phosphate) complex. Catalytic experiments have demonstrated that the presence of the coordinated hydroxide anion and water molecules in precatalyst ( 2 ) substantially lowered the catalytic activity of the system prepared from ( 2 ) in butadiene and isoprene polymerization compared to the catalytic system based on the neodymium tris[bis(2,6‐diisopropylphenyl) phosphate] complex, which contains neither OH nor H 2 O ligands.