Acyl‐ und Alkylidenphosphane. XXXI. Bis(2,4,6‐trimethylbenzoyl)phosphan und ‐arsan—Synthese und Struktur

Abstract

Aus Lithium‐bis(trimethylsilyl)phosphid · 2THF1 oder Lithiumdihydrogenarsenid · 2THF und 2,4,6‐Trimethylbenzoylchlorid im Molverhältnis 3:2 zugängliches Lithium‐bis(2,4,6‐trimethylbenzoyl)phosphid · 2THF (1a) bzw. ‐arsenid · 2THF (1b) [16] setzen sich mit Tetrafluoroborsäure · Diethylether‐Addukt in nahezu quantitativer Ausbeute unter Lithium‐Wasserstoff‐Austausch zu Bis(2,4,6‐trimethylbenzoyl)phosphan (2a) sowie zum entsprechenden Arsan 2b um. Nach der Synthese einer nun größeren Zahl von Derivaten [19] lassen sich für die zugehörigen Keto‐ und Enol‐Tautomeren charakteristische NMR‐Parameter angeben. Nach den Ergebnissen von Röntgenstrukturanalysen (Raumgruppe Fdd2; a = 1 486,1(4)/1 501,7(4); b = 2975,8(12)/3000,6(6); c = 827,9(2)/822,7(2) pm bei—100° ± 3°C; Z = 8; Rw = 0,034/0,040) liegen die beiden zueinander isotypen Verbindungen 2a und 2b im Festkörper als Enol‐Tautomere mit sehr kurzer, symmetrischer O‥H‥O‐Brücke (O‥O243/245 pm) vor. Die Moleküle zeigen aufgrund ihrer speziellen Lage die Punktsymmetrie 2; charakteristische Bindungslängen und ‐winkel sind: PC 177; AsC 190; CO 126/128; CC (Aren) 150/147; OH 122/128 pm; CPC 98° CAsC 97° PCO 125° AsCO 123° PCC 117° AsCC 118°; COH 99°/116° OHO 173°/146°. Die unterschiedliche Geometrie der beiden Enolringe wird diskutiert.

Charge Density Distribution in a Metallaphosphane

“…H1 is unambiguously located at N1, which seems surprising as in the parent dipyridylphosphane HPPy 2 the hydrogen atom is bonded to the phosphorus atom ( 31 P NMR: 1 J (P,H) = 225 Hz; IR, n s (P-H): ñ = 2312 cm À1 ), [32] and to date only diacylphosphanes show keto-enol tautomerism in solution. [33] The symmetrical coordination of the two tungsten atoms to the central phosphorus atom is in geometrical accordance with the two lone pairs of form E in Scheme 2. The PÀW distances are almost equal to those in [{(CO) 5 W} 2 {(m-P)H 2 }] À .…”

Di(benzothiazol‐2‐yl)phosphanide as a Janus‐Head Ligand to Caesium

“…Phosphane 2 is reminiscent of diacylphosphanes, which show keto-enol tautomerism in solution. [20] The N À H tautomer is stable in diethyl ether causing a signal in the 31 P NMR spectrum at d = 6.81 ppm with a 3 J P,H coupling constant of 8 Hz. If, for example, tetrahydrofuran is used as the solvent, a second signal at d = À65.77 ppm starts growing, which can be assigned to the P À H tautomer.…”

Acyl‐Phosphide Anions via an Intermediate with Carbene Character: Reactions of K[PtBu2] and CO

“…The corresponding 31 P{ 1 H} and 31 PNMR signals were found to be triplets at d = 35.3 ppm, indicating the incorporation of two equivalents of 13 CO.R epeating the reaction of [ 13 C]2 with unlabeled CO afforded an analogous doublet ( 1 J P-C = 97 Hz) 31 Ps ignal with ac hemical shift of d = 35.4 ppm. The[(OCtBu) 2 P] À ligand was found to be planar with average PÀCa nd CÀOb ond distances of 1.812(2) and 1.234(2) , respectively,a nd aC ÀPÀCa ngle of 105.28 8.T his fragment is bound to the potassium ion by KÀOb onds that were determined to be 2.729(1) and 2.689(1) .The KÀOdistances to the crown-ether fragment in 5 were found to average 2.902 .I ti sn oteworthy that the groups of Becker [15] and Grützmacher [16] have previously reported related diacyl-phosphides.B ecker and colleagues described various metal salts of related anionic ligands [17] and Goicocechea and coworkers have described related bis(carbamoyl) phosphides. 5 was crystallized from aT HF/pentane solution and the X-ray study confirmed the above formulation as the Ks alt of the diacyl-phosphide anion ( Figure 5).…”