Biomedical subjects

Robert D. Culp

Publications and source records attributed to Robert D. Culp.

3 recordsLinked to original sources

PubMed1997

Monomeric Titanium(IV) Azides as a New Route to Titanium Nitride.

The reaction of Ti(NMe(2))(4) with 2 equiv of Me(3)SiN(3) in toluene solution affords a dark red polymeric material of composition [Ti(NMe(2))(2)(N(3))(2)](n) (1). If the reaction is carried out in pyridine (py) solution, dark red, crystalline [Ti(NMe(2))(2)(N(3))(2)(py)(2)] (2) is formed. Analogous reactions of Ti(NMe(2))(4) with 2 or 1 equiv of Me(3)SiN(3) in the presence of 1 equiv of bipyridyl (bipy) in toluene solution afford brown crystals of [Ti(NMe(2))(2)(N(3))(2)(bipy)] (3) and dark red crystals of [Ti(NMe(2))(3)(N(3))(bipy)] (4), respectively. Crystallographic data for 2: orthorhombic, C222(1), a = 7.120(1) Å, b = 15.899(3) Å, c = 16.946(4) Å, V = 1918.3(6) Å(3), rho = 1.310 g/cm(3), Z = 4. Crystallographic data for 3: monoclinic, I2/a, a = 7.358(2) Å, b = 16.808(4) Å, c = 14.837(6) Å, beta = 95.40(2) degrees, V = 1826.8(1) Å(3), rho = 1.368 g/cm(3), Z = 4. Crystallographic data for 4: monoclinic, P2(1)/c, a = 15.682(2) Å, b = 8.814(1) Å, c = 15.128(1) Å, beta = 108.39(1) degrees, V = 1984.2(4) Å(3), rho = 1.267 g/cm(3), Z = 4. Compounds 1 and 2 deposit thin films of titanium nitride (TiN) on silica and/or nickel substrates in the temperature range 300-400 degrees C. The TiN films deposited from precursor 2 are superior to those deposited from 1.

Journal Article↗

PubMed1997

Synthesis and Structures of Intramolecularly Base-Coordinated Group 15 Aryl Halides.

Four group 15 monochlorides of the type EAr(2)Cl [Ar = 2-[(dimethylamino)methyl]phenyl, 2-(Me(2)NCH(2))C(6)H(4) (C(9)H(12)N), E = Sb (4), E = Bi (5); Ar = 8-(dimethylamino)-1-naphthyl, 8-(Me(2)N)C(10)H(6) (C(12)H(12)N), E = Sb (6), E = Bi (7)] have been prepared via the salt elimination reactions of 2 equiv of either 2-(Me(2)NCH(2))C(6)H(4)Li or 8-(Me(2)N)C(10)H(6)Li with ECl(3). Four related group 15 dihalides of the type EArX(2) [Ar = 8-(Me(2)N)C(10)H(6), X = Cl, E = As, (8), E = Sb (9); Ar = 2-(Me(2)NCH(2))C(6)H(4), X = Cl, E = Bi (10); X = I, E = Bi (11)] have been prepared via the salt elimination reactions of equimolar amounts of 8-(Me(2)N)C(10)H(6)Li or 2-(Me(2)NCH(2))C(6)H(4)Li with EX(3). The X-ray crystal structures of 4-6, 8, 9, and 11 are described, and the observed trends in the degree of intramolecular coordination of the nitrogen atoms are consistent with the view that the Lewis acidity of these complexes is associated with the E-X sigma orbitals. Crystal data for 4: triclinic, space group P&onemacr;, a = 9.1483(1) Å, b = 9.4868(1) Å, c = 12.9776(2) Å, alpha = 70.614(8) degrees, beta = 85.738(9) degrees, gamma = 83.094(9) degrees, V = 1054.0(2) Å(3), Z = 2, R = 0.0420. Crystal data for 5: monoclinic, space group P2(1)/c, a = 11.9498(1) Å, b = 11.4695(1) Å, c = 13.9456(8) Å, beta = 104.536(6) degrees, V = 1850.2(3) Å(3), Z = 4, R = 0.0375. Crystal data for 6: monoclinic, space group P2(1)/n, a = 9.4991(8) Å, b = 23.455(4) Å, c = 9.726(1) Å, beta = 100.629(8) degrees, V = 2129.8(4) Å(3), Z = 4, R = 0.0406. Crystal data for 8: orthorhombic, space group P2(1)2(1)2(1), a = 9.713(3) Å, b = 9.835(4) Å, c = 13.310(3) Å, V = 1273.8(5) Å(3), Z = 4, R = 0.0695. Crystal data for 9: orthorhombic, space group P2(1)2(1)2(1), a = 9.7140(3) Å, b = 10.0196(1) Å, c = 13.444(3) Å, V = 1308.5(3) Å(3), Z = 4, R = 0.0320. Crystal data for 11: monoclinic, space group P2(1)/c, a = 7.9455(7) Å, b = 19.3949(3) Å, c = 8.6226(9) Å, beta = 93.338(9) degrees, V = 1326.5(2) Å(3), Z = 4, R = 0.0379.

Journal Article↗

PubMed1996

Ring Systems Containing Anionic and Cationic Gallium Centers: Structural and Bonding Considerations.

The metathetical reaction of 2-(dimethylamino)benzyllithium (Bz(N)Li) with GaCl(3) afforded the salt [Bz(N)(2)Ga][GaCl(4)] (4), the X-ray crystal structure of which revealed a four-coordinate cationic gallium center featuring two Ga-C sigma-bonds and two N-->Ga dative bonds. (Crystal data for 4: monoclinic, space group P2(1)/n, a = 11.519(2) Å, b = 18.254(4) Å, c = 12.506(3) Å, beta = 117.40(3) degrees, V = 2334.6(9) Å(3), Z = 4, R = 0.545). Two Ga.Cl interionic contacts, while somewhat long, are sufficiently strong to render the geometry of 4(+)() roughly midway between tetrahedral and octahedral. Treatment of 1,4-di-tert-butyl-1,4-diazabutadiene (DAB) with 2 equiv of GaCl(3) afforded [(DAB)GaCl(2)][GaCl(4)] (7), which, by means of X-ray analysis, was shown to possess a cation (7(+)()) with localized C=N bonds and N-->Ga dative interactions with a [GaCl(2)](+) moiety. (Crystal data for 7: orthorhombic, space group Pbca, a = 11.882(2) Å, b = 17.289(3) Å, c = 20.424(4) Å, V = 4195.5(11) Å(3), Z = 8, R = 0.460). The structure of 7(+)() is relevant to discussions of the bonding in both neutral DAB complexes of the group 13 elements and the skeletally isoelectronic anion [Me(4)C(4)GaCl(2)](-) (9(-)()). The structure of the [NEt(4)](+) salt of the latter (9) has been determined by X-ray diffraction. (Crystal data for 9: monoclinic, space group P2(1)/n, a = 9.967(1) Å, b = 13.073(2) Å, c = 15.345(2) Å, beta = 96.76(1) degrees, V = 1985.5(4) Å(3), Z = 4, R = 0.721).

Journal Article↗