Plugin with id 'org.sonarqube' not found

I am trying to implement sonar with gradle for code-coverage measure for my project. we are using gradle-4.0.1 and sonarqube-6.4 .

when I run gradle sonarqube from command line I get this error-

Plugin with id 'org.sonarqube' not found.

I tried few code changes but no luck, please help. My build.gradle file is as below-

buildscript {
    ext {
        springBootVersion = '1.5.4.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'org.sonarqube'
apply plugin: "jacoco"
apply plugin: "java"
apply plugin: "war"
apply plugin: "org.springframework.boot"


sonarqube {
  properties {
    property "sonar.projectName","Spring4WebService Code Coverage Demo"
    property "sonar.projectKey", "org.sonarqubeJacocoCodeCoverage"
    property "sonar.reportPath" , "${project.buildDir}/jacoco/test.exec"
  }
}


test{
  ignoreFailures = true
}


ext {
    jacocoVersion = '0.7.6.201602180812'
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

repositories {
    mavenCentral()
}


sourceSets {
  main.java.srcDir "src/main/java"
  test.java.srcDir "src/test/java"
}

springBoot {
  mainClass = "com.concretepage.config.WebAppInitializer"
}

dependencies {
    compile('org.springframework.boot:spring-boot-starter-web','com.fasterxml.jackson.core:jackson-databind')
    testCompile('org.springframework.boot:spring-boot-starter-test')
}

jacoco{
  toolVersion = "${jacocoVersion}"
}

jacocoTestReport {
 reports{
  html.enabled=true
  xml.enabled=true
  csv.enabled=true
 }
}