Phosphonium‐benzylide und alkali‐[phosphoniumbis(benzylide)]: Beispiele für salzfreie Ylide und korrespondierende Alkalikomplexe

Abstract

Aus Phosphanvorstufen wurden mit Benzylbromid die Phosphoniumsalze R2P(CH2C6H5)2+ Br-(mit R = CH3, CH2C& oder C6H5) hergestellt und in die korrespondierenden Benzyl(benzy1i-den)phosphorane R2P(CH2C6Hs) = CHC& (3a -c) iibergefuhrt. Diese Y lide ergeben mit Lithiumalkylen Metallierungsprodukte des Typs R2P(CHGHs)2Li (4a -c), mit NaNH2 die analogen Natriumkomplexe R2P(CHC6H5)2Na (Sa -c). Spektroskopische Untersuchungen zeigen eine koordinative Wechselwirkung der Metallionen mit je zwei aquivalenten Benzylidfunktionen an. Die Delokalisierung der Carbanionladung auf die 0-und pPositionen des Phenylrings begunstigt die Komplexierung des gr6Reren Natriumions. Auch entsprechende Ylidkomplexe des Kaliums sind zuganglich. -Das Kaliumderivat von (CH3)2P(CH2C6Hs) = C H C~H S (6a) kristallisiert solvatfrei, seine Struktur wurde durch eine R6ntgenbeugungsanalyse bestimmt. Das Gitter enthalt keine diskreten Komplexmolekule, sondern ist als Koordinationspolymeres zu beschreiben, in dem die Metallatome vorzugsweise Nahordnungswechselwirkungen rnit den ylidischen Carbanionen sowie mit den negativierten 0-undp-C-Atomen der Benzylidringe eingehen. Leitfahigkeitsmessungen zeigen jedoch, daR das Metall in LBsung an den Ylidliganden gebunden bleibt und keine nennenswerte elektrolytische Dissoziation eintritt. Phosphonium Benzylides and Alkali [Phosphoniumbis(benzylides)]: Salt-free Ylides and Their Corresponding Alkali ComplexesPhosphonium salts R2P(cH2c6H5$ Br-(with R = CH3, CH2C6H5, or C6H5) were prepared from phosphane precursors with benzyl bromide and converred into the corresponding ylides R2P(CH2C6H5) = CHGH5 (3a -c). These ylides react with lithiumalkyls to form metalation products R2P(CHGH5)2Li (4a-c), and with NaNH2 to form the analogous sodium complexes R,P(CHC6Hs)2Na (Sa -c). In spectroscopic investigations a coordinative interaction of the metal with two equivalent benzylide functions is detected. Delocalization of the carbanionic charge onto the orfho and para positions of the phenyl rings favours the complexation of the larger sodium cation. The corresponding ylide complexes of potassium are also available. -The crystal structure of the solvent-free potassium derivative of (CH3)2P(CH2C6H5j =CHC& (6a) could be determined by X-ray diffraction. The lattice does not contain discrete complex molecules, but is rather to be described as a coordination polymer with the metals interacting preferentially with ylidic carbanions and the negativated orfho and para carbon atoms of the benzylide rings. Conductivity measurements are showing, however, that the metal remains attached to the ylide ligand in solution, and that no significant electrolytical dissociation occurs.Chem. Ber. 114(1981)

Donor-Free Alkali Metal Thiolates: Synthesis and Structure of Dimeric, Trimeric, and Tetrameric Complexes with Sterically Encumbered Terphenyl Substituents

“…The K−centroid distances in 7 range from 3.067−3.152 Å. These are longer than the 2.97 Å in [K(C 6 H 6 )][K{C(SiMe 3 ) 2 SiMe 2 Ph} 2 ] 21a21b.…”

Heavy Alkali Metal Arenedithiocarboxylates: A Facile Synthesis, Dimeric Structure, and Nonbonding Interaction between the Metals and Aromatic Ring Carbons

“…The interaction number of potassium is 8 (six sulfur and two carbon atoms) (Figure , parts a and b). The two carbons are the ipso and ortho carbons of the phenyl ring of a neighboring molecule (K + - η 2 ) [K1−C2 #2 = 3.209(2) Å and K1−C7 #2 = 3.110(3) Å, respectively] (Figure , part a; Figure , part a). , Such interaction between an aromatic carbon and alkali metals is the first example for the compounds having both carboxylate and chalcogenocarboxylate groups, although the following have been reported: η 2 and η 3 interactions between Ph 2 P(PhCH)K (K− C, 3.01∼3.25 Å); (2-C 5 H 4 N)(Ph 2 CHPh 2 CHK·2THF); Ph 2 (2-C 5 H 4 N)CK·PMDTA·THF (K−C, 3.14−3.46 Å); η 5 = dianion triple salt where K + interacts η 5 to the ring (K−C, 3.02−3.12 Å) which was obtained by reduction of tetraphenylbutadiene with potassium; η 6 = Ph 3 CK·THF·PMDTA (K−C, 3.14−3.25 Å); [(Ph 3 P) 2 (Ph 2 PC 6 H 4 )RuH 2 ] 2 C 10 H 8 ·Et 2 O (K−C, 2.61−2.97 Å), (PhMe 2 P)OsH 3 K (K−C, 3.12−3.60 Å), [(2,6- i -Pr 2 C 6 H 3 O) 4 Nd]K (K−C, 3.12−3.47 Å), η 6 -benzene contacts, alkali metal graphite intercalates (K−C, 3.05 Å), [(PMDTA)PhCH 2 M] [M = K (M−C, 3.15−3.29 Å), M = Rb (Rb−C, 3.35−3.64 Å)], N -rubidiocarbazole·PMDTA (Rb−C, 3.42−3.68 Å), and Ph 3 CRb·M(PMDTA) n (Rb−C, 3.35−3.64 Å) 3 Packing (a) of potassium 4-methylbenzenecarbodithioate ( 3b ) and coordination sphere (b) around the potassium.…”

The Phosphonium Dibenzylide Anion as a Ligand in Organobarium Chemistry

“…Currently, no other structures of heavier alkaline-earth bis-ylides have been reported. There is, however, a structure of a closely related alkali-metal complex Me 2 P(benzylide) 2 - K + , which forms a polymer in the solid state . In this structure, the dibenzylide anion adopts a comparable C 2 symmetry and the K + ion, which is about equal in size to the Ba 2+ ion, is similarly bonded between the two benzyl systems.…”

“…This is due to fast proton transfer from the benzyl to the benzylide group, interconverting these functionalities. This process is catalyzed by small quantities of HN(SiMe 3 ) 2 and generally observed in ylide compounds …”