Preparation, X-ray structure, and dynamic solution behaviour of N , N ', N ''-tris(2,6-diisopropylphenyl)- guanidine, and its reaction with molybdenum carbonyl
2000; NRC Research Press; Volume: 78; Issue: 12 Linguagem: Inglês
10.1139/v00-142
ISSN1480-3291
AutoresRobyn E Boeré, Renè T. Boeré, Jason D. Masuda, Gotthelf Wolmershäuser,
Tópico(s)Synthesis and characterization of novel inorganic/organometallic compounds
ResumoThe reaction of N,N'-bis(2,6-diisopropylphenyl)carbodiimide with lithium 2,6-diisopropylanilide, quenching with water and recrystallization from heptane produces the symmetric guanidine [DipNH] 2 C=NDip which crystallizes in the triclinic system, space group P[Formula: see text], a = 10.6513(11), b = 10.8997(11), c = 16.2961(17) Å, α = 80.524(12), β = 78.921(13), γ = 70.060(12)°, V = 1735.2(3) Å 3 , Z = 2. The molecule crystallizes with three perpendicular 2,6-diisopropylphenyl groups, which surround and shield the central CN 3 unit, and provide (almost) three-fold symmetry around the central atom. Its dynamic solution behaviour has been studied by VT NMR between -90 and +180°C, and is consistent with three distinct barriers to N-C Ar rotation. Preliminary estimates of the Gibbs free energy of activation for the lower two barriers are 56 ± 2 and 73 ± 2 kJ mol 1 . Reaction of the title compound with Mo(CO) 6 in refluxing n-heptane produces [DipNH] 2 C=NDip·Mo(CO) 3 , a complex in which Mo(CO) 3 is η 6 -coordinated to one of the diisopropylphenyl rings.Key words: crystal structure, diisopropylaniline, guanidine, bulky ligands.
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