Peter Krommes

Cyclopentadienyls (CH3)2Mσ-C5H5 of indium, antimony and bismuth

The reaction of Me3In with monomeric cyclopentadiene yields the stable Me2InCp (I): the same product may be obtained by the reaction of (Me2InNMe2)2 with C5H6 via a soluble adduct Me2InCp · HNMe2 (II) which is easily converted into Me2InCp, for which a polymeric structure is suggested. Reactions of Me2SbNMe2 and Me2BiN(Me)SiMe3 with C5H6 afford thermally labile cyclopentadienyls Me2SbCp (III) and Me2BiCp (IV). Compounds I–IV have been studied through IR, 1H NMR and mass spectroscopy; the cyclopentadienyl ligand is σ-bonded to the metals in Me2SbCp and Me2BiCp.

Die molekül- und kristallstruktur von thallium-tris(bistrimethylsilylamin), Tl[N(SiMe3)2]3

Abstract The molecular and crystal structure of tris(bistrimethylsilylamin)thallium was determined by means of single-crystal X-ray spectroscopy: in the space group P 3 1 c with a = 16.447(7), c = 8.456(7) A; and D c = 1.149 g cm −3 two molecules are located in the unit cell. The compound is isomorphous to the analogues Fe[N(SiMe 3 ) 2 ] 3 or Al[N(SiMe 3 ) 2 ] 3 , respectively, which show a propellar-twist of the Si 2 N-groups versus the plane of the metal atom and the three nitrogen-atoms: Tl(N) 3 /Si 2 N 49.1°; SiNSi 122.6°; NSiC 111.8°; CSiC 107.1°; TlN 2.089 A;; SiN 1.738 A;; SiC 1.889 A;.

Metallorganische diazoverbindungen : VIII. Reaktionen von arsen- und antimonamiden mit diazoessigsäureäthylester

The preparation and properties of the organoarsenic diazoalkanes (Me2N)2-AsC(N2)CO2Et (I), MeAs(NMe2)C(N2)CO2Et (II) and MeAs[C(N2)CO2Et]2 (III), synthesized from the reaction of As(NMe2)3 or MeAs(NMe2)2 with HC(N2)-CO2Et are described; IR, 1H NMR and 13C{1H} PFT spectra of compounds I-III are reported and discussed. Control experiments at room temperature of treatment of Sb(NMe2)3 with CH3CO2Et lead in a smooth reaction to antimony alcoholate, Sb(OEt)3, and CH3CONMe2, whereas As(NMe2)3 did not react; from these results a reaction scheme for analogous, but complex experiments of Sb(NMe2)3 and MeSb-(NMe2)2 with HC(N2)CO2Et is derived.

Die kristallstruktur des tris(monohapto)cyclopentadienylantimon(III), (1h-C5H5)3Sb

(C 5 H 5 ) 3 Sb was synthesized by treatment of Sb(NMe 2 ) 3 with excess monomeric cyclopentadiene in quantitative yield. The compound crystallizes in the space group P 2 1 / c with Z = 4; d c 1.606 g cm −3 ; a 1036.5(15) pm; b 872.1(10 pm; c 1563.6(21) pm; β 109.47(12)°. At 223 K a set of 1849 unique reflections was obtained, 1574 with F > 2σ( F ) have been used for refining the structure; full-matrix treatment with individual anisotropic temperature factors led to a reliability index R w = 0.025. The molecular structure unequivocally shows the existence of σ-bonded ( 1 h -monohapto)cyclopentadienyl rings with approximate tetrahedral angles between the “best planes” of the five-membered rings and the SbC bond directions. The space-demanding non-bonding electron pair at the Sb atom influences the molecular packing: channels are formed along the b -axis of the elementary cell.

Darstellung und chemie von Me2TlN(SiMe3)2 und Tl[N(SiMe3)2]3

Summary The preparation of Tl[N(SiMe 3 ) 2 ] 3 and its mass spectrum is described; attempts to synthesize Me 2 InN(SiMe 3 ) 2 failed, but Me 2 TlN(SiMe 3 ) 2 was obtained as a highly reactive substance in low yield. Tl[N(SiMe 3 ) 2 ] 3 reacts with Et 2 O/HN 3 forming a six coordinate azido complex H 3 Tl(N 3 ) 6 ; low temperature reaction of Tl[N(SiMe 3 ) 2 ] 3 with monomeric cyclopentadiene affords Tl I Cp; the reported existence of TlCp 3 is questioned.

Metallorganische Diazoverbindungen : IX. Me2AsCHN2, ein neues metalorganisch monosubstituiertes Diazomethan

Abstract Me 2 AsCHN 2 (I) was obtained in 25% yield by treating Me 2 AsNMe 2 in the presence of stoichiometric amounts of Me 3 SnCl with a large excess of CH 2 N 2 at room temperature. Treatment of I with P(NMe 2 ) 3 afforded a 1 : 1 mixture of isomers cis -, trans -tris(dimethylamino)phosphine(dimethylarsenformaldazine), cis -, trans -Me 2 AsCHNNP(NMe 2 ) 3 , which in benzene solution rearranged to the cis -isomer. Analogous treatment of Me 2 AsC(N)CO 2 Et with P(NMe 2 ) 3 yielded tris(dimethylamino)phosphine-(dimethylarsen carbethoxyformaldazine), Me 2 As(CO 2 Et)CNNP(NMe 2 ) 3 , whereas (Me 2 As) 2 CN 2 did not react under similar conditions.

Metallorganische diazoalkane : XIII. Reaktionen metallorganischer diazoalkane mit P(NMe2)3 zu metallorganischen phosphazinen LnM(R)CNNP(NMe2)3

Abstract Staudinger reactions of 20 organometallic diazoalkanes and of their parent compounds CH 2 N 2 , HC(N 2 )CO 2 Et, HC(N 2 )C(O)Me and HC(N 2 )C(O)Ph with a strong basic phosphine P(NMe 2 ) 3 are described and were classified into five groups 1–5 of different reactivity. Mono-diazomethanes L n MCHN 2 (for L n M = Me 3 Si, Me 2 As) react to give ( cis , trans ) isomers of the corresponding phosphazines L n MC(H)NNP(NMe 2 ) 3 ; a stepwise reaction of functional diazogroups in organometallic bis-diazoalkanes, e.g. Hg[C(N 2 )CO 2 Et] 2 , has been observed. Different reactivity of organometallic diazoalkanes cannot be rationalized by known spectroscopic data but can be interpreted by steric effects. In analogy to reactions of isoelectronic azides a transition state of the Staudinger reaction is suggested with an attack of the basic phosphine at the electrophilic α-nitrogen atom and following rearrangement into the N β -Staudinger adduct. Trimethylgermaniumdiazomethane, Me 3 GeCHN 2 , was obtained as a novel monosubstituted organometallic diazoalkane and is fully characterized.

Metallorganische diazoalkane : XV. Bindungsverhältnisse und elektronenstrukturen in metallorganischen diazoalkanen: das beispiel bis(trimethylstannyl)diazomethan (Me3Sn)2CN2

Abstract Bis(trimethylstannyl)diazomethane has been investigated by various spectroscopic methods and the results are compared with those for CH 2 H 2 and other homologues of the organometal diazoalkane series: tetrahedral coordinated, strongly deshielded tin atoms are detected by 119 Sn-Mossbauer spectroscopy; 1 H, 13 C, 15 N and 119 Sn NMR data reveal a regular distribution of enhanced electron density along the CNN-moiety. IR data in combination with exact and approximate mathematical treatment afford calculation of the force constants f (NN) and f (NC); a model of strongly coupled vibrations is supported by decrease of bond order in the NN-bonding and the increase of bond order in the NC-bonding. PE-spectra supply first ionisation potentials and show increasing destabilisation of the π-MO of the CNN-group by substitution of hydrogen vs. organometallic groups at the α-C-atom: according to the series H > = Ge > Sn > Pb the first IP of CH 2 N 2 (9.00 eV) decreases to 7.53 eV for (Me 3 Sn) 2 CN 2 .

Organometallic diazoalkanes XII. Bis(dimethylthallium)diazomethane [Me2Tl]2CN2, a first example of the diazomethyl anion [CN2]2−

Abstract Reactions of (Me 2 TlNMe 2 ) 2 or Me 3 Tl with diazomethane gave ionic (Me 2 Tl) 2 CN 2 in a quantitative yield. Bis(dimethylthallium) diazomethane is the first compound known to contain the linear [CN 2 ] 2− anion. [Me 2 Tl] 2 CN 2 does not react with P(NMe 2 ) 3 in a Staudinger reaction to give phosphazine or undergo the Huisgen reaction with MeO 2 CCCCO 2 Me.

Organometallic diazoalkanes : X. 13C {1H} PFT spectra of organometallic diazoalkanes of the main group elements

Abstract Direct metal—carbon coupling constants 1 J (M 13 C) and chemical shift data are reported for the organometallic diazoalkanes L n MC(N 2 )R [L n M = Me 3 Si; Me 3 Ge; Me 3 Sn; Me 3 Pb; MeHg; EtO 2 C(N 2 )CHg; R = H; (Me) n M; EtO 2 C] and the compounds Me 2 MC(N 2 )R′ [M = As, Sb, Bi; R′ = H; Me 2 M; EtO 2 C], including various other diazoalkanes of arsenic. Electron release by the methyl—metal substituents leads to strong shielding of the α-carbon atoms in heterodiazoalkanes.