Partial substitution of boron for phosphorus in the ternary phosphide superconductors ZrRuP and LaRu2P2 induces highly anisotropic structural changes and suppresses the superconducting transition temperatures. Undoped ZrRuP [hexagonal, a = 6.445(4) Angstrom, c = 3.765(2) Angstrom] systematically expands for ZrRuP1-xBx (x = 0.05, 0.10, 0.15, 0.20, 0.40) in the a direction to 6.949(4) Angstrom and shrinks in the c direction to 3.601(3) Angstrom. Superconductivity is still present in the boron-substituted samples, although T-c drops from 10.1 K in ZrRuP to 5.6 K in ZrRuP0.6B0.4. LaRu2P2 [tetragonal, a = 4.032(2) Angstrom, c = 10.632(7) Angstrom] remains essentially unchanged along the a axis [a = 4.037(l) Angstrom] upon substitution at a starting composition of LaRu2P1.6B0.4, but shrinks along the c axis to 10.477(5) Angstrom. Accordingly, the superconducting Tc drops from 4.0 K for Lau(2)P(2) to 2.0 K for LaRu2P1.6B0.4. (C) 2004 Elsevier Ltd. All rights reserved.