Hans E. Parge

Possible pre-dissociation of diorganotin dihalide complexes: relationship between antitumour activity and structure.

An examination of crystallographic data has indicated that the structure/activity relationship for diorganotin dihalide complexes is different from that of other metal dihalides, in that the Sn-N bond lengths appear to determine the antitumour activity.

Sterically hindered metal alkenyls. Part 1. Synthesis, reactions, and crystal and molecular structures of some palladium and platinum σ-alkenyls

The compounds trans-[PtBr{C(C10H15)CH2}(PEt3)2](1)(C10H15= adamant-1-yl), trans-[MBr{C(C10H7)CMe2}(PEt3)2][M = Pd (2) or Pt (3); C10H7= naphth-1-yl], and trans-[MBr{C(Ph)CMe2}(PEt3)2][M = Pd (4) or Pt (5)] have been prepared from Grignard [for (2) and (3)] or lithium reagents [for (1), (4), and (5)] and appropriate dichlorobis(phosphine)metal derivatives. Full single-crystal X-ray data are reported for (1) and (3), and reveal unusually long Pt–C(sp2) bonds. Insertion reactions into these M–C bonds occur with MeNC [for (1), (3), and (5)], and with CO [for (1) and (3)]; the latter, the first reported insertion into a Pt–C(sp2) bond, occurs under mild conditions as expected for the abnormally long M–C bonds.

Synthesis and molecular structures of nido-[9-(η-C5H5)-7,8,9-C2NiB8H11], nido-[9-(η-C5H5)-µ10,11-(Ph3PAu)-7,8,9-C2NiB8H10], and closo-[1,3-(η-C5H5)2-1,2,3,4-CrCCrCB8H10]; evidence for a multiple metal–metal bond in a dimetallacarbaborane

From nido-5,6-C2B8H12, the compounds nido-[9-(η-C5H5)-7,8,9-C2NiB8H11], nido-[9-(η-C5H5)-µ10, 11-(Ph3PAu)-7,8,9-C2NiB8H10], and closo-[1,3-(η-C5H5)2-1,2,3,4-CrCCrCB8H10] have been synthesised, and their structure identities established by X-ray crystallography.

A hydrogen-1 nuclear magnetic resonance, mass spectral and extended Hückel study of some olefin complexes of rhodium(I) and iridium(I) and the crystal and molecular structure of η4-2,4-dimethylpenta-1,4-diene(η5-formylcyclopentadienyl)rhodium(I)

A 1H NMR study of monosubstituted η-cyclopentadienyl-rhodium(I) complexes of type LLRh(C5H4X) and -iridium(I) complexes of type L2Ir(C5H4X) (L = ethene, LL = 1,3- or 1,5-diolefin; X = C(C6H5)3, CHO, or COOCH3) has been carried out. For complexes of both metals in which the neutral ligand is ethene or a non-conjugated diolefin the NMR spectra of the cyclopentadienyl protons are unusual in that H(2), H(5) resonate to high field either at room temperature or below. n nThe corresponding NMR spectra for the cyclopentadienyl ring protons of complexes where the neutral ligand is a conjugated diene are, with one exception, normal. n nA single crystal X-ray structural analysis of (η4-2,4-dimethylpenta-1,4-diene)(η5-formylcyclopentadienyl)rhodium(I) (which exhibits an abnormal 1H NMR spectrum) reveals substantial localisation of electron density in the C(3)ue5f8C(4) Cp ring bond (1.283(33) A) which may be consistent with a contribution from an ‘allyl-ene’ rotamer to the ring—metal bonding scheme. An extended Huckel calculation with self consistent charge iteration was performed on this complex. n nThe results predict a greater Mulliken overlap population for the C(3)ue5f8C(4) bond in the cyclopentadienyl ring and show that the localisation is dependent on both the Cp ring substituent and the nature of the diolefin. The mass spectral fragmentation patterns of some representative diene complexes of iridium(I) and rhodium(I) are presented.

Crystal and molecular structures of [MCl(CPhCMe2)(η-C5H5)2](M = Zr or Hf) and [TiCl0.5 Br0.5(CPhCMe2)(η-C5H5)2]: an unusual π-interaction with the metals and molecular orbital calculations on model compounds

The compounds [MCl(CPhCMe2)(η-C5H5)2](M = Zr or Hf) and [TiCl0.5Br0.5(CPhCMe2)(η-C5H5)2], whose structures have been determined by X-ray diffraction, all show a π-type of interaction between the phenyl ring and the metal. This is revealed by (i) the conformation of the alkenyl ligand, (ii) the small value of the angle M–C(1)–C(5), which is 100.3(3)° when M = Zr and 105.7(2)° when M = Ti, and (iii) the lengthening of the M–Cl bond, to 2.480(1)A for M = Zr. A specific electronic effect is demonstrated by charge-iterated extended-Huckel calculations on related model systems.

Reaction of zero-valent cobalt and iron species with seven-atom carbaboranes; molecular structures of [4-(Et3P)-1,7-Me2-µ4,8-{Co(H)-(PEt3)2-µ(H)-µ(PEt2)}-1,4-7-CCoCB5H4] and [4,4,4-(ButNC)3-1,7-Me21-1,4,7-CFeCB5H5]

Reaction of closo-2,4-Me2-2,4-C2B2H5 with [Co(PEt3)4] affords a novel dicobalthydrido-complex containing a phosphido-bridge, whereas [Fe(CNBut)5] reacts to form a mononuclear 8-atom cage, in which the iron atom has a cluster connectivity of five.

(2,2'-Bipyridyl-N,N')di-n-butyldichlorotin(IV)

The title compound, [SnCl 2 (C 4 H 9 ) 2 (C 10 H 8 N 2 )], is the product of the reaction of 2,2-bipyridyl with dibutyltin dichloride. The Sn IV centre is octahedrally coordinated by a bidentate 2,2-bipyridyl ligand, two cis chlorides and two trans butyl groups. The extensively delocalized bipyridyl group is not absolutely planar, with the pyridyl rings twisted by 7.5 (3)°.

Metal cluster expansion by addition of low-valent group 4B reagents: crystal and molecular structure of [Os3SnH2(CO)10{CH(SiMe3)2}2]; a compound with hydrogen bridging osmium and tin

Cluster expansion of [Os3H2(CO)10] with [SnR2][R = CH(SiMe3)2] take place in high yield to give [Os3SnH2(CO)10R2], the first closed triosmium–main-group metal cluster to be structurally characterized; a novel feature is the presence of a hydrogen atom bridging the tin atom and one of the osmium atoms.

Alkenyl derivatives of the metals. Oxidative addition to intermediate tin(II) alkenyls; isolation, and crystal and molecular structure of n-butyltris(triphenylethenyl)tin(IV)

Reaction of tin(II) chloride with Li(CPhCPh2) at –78 °C in diethyl ether–hexane–tetrahydrofuran affords a deep red solution whose colour fades on warming, and which we believe contains the (unstable) first dialkenyltin(II) species. The latter survives long enough at low temperatures to undergo intermolecular oxidative addition, and one such adduct leads ultimately to the formation of Sn(CPhCPh2)3Bun, which has been fully characterised including a crystal and molecular structure study. The mechanism of formation of the final product has been examined and results are reported.